| Rfc | 8620 |
|---|
| Title | The JSON Meta Application Protocol (JMAP) |
|---|
| Author | N. Jenkins, C. Newman |
|---|
| Date | July 2019 |
|---|
| Format: | TXT, HTML |
|---|
| Updated by | RFC9404, RFC9670 |
|---|
| Status: | PROPOSED STANDARD |
|---|
|
Internet Engineering Task Force (IETF) N. Jenkins
Request for Comments: 8620 Fastmail
Category: Standards Track C. Newman
ISSN: 2070-1721 Oracle
July 2019
The JSON Meta Application Protocol (JMAP)
Abstract
This document specifies a protocol for clients to efficiently query,
fetch, and modify JSON-based data objects, with support for push
notification of changes and fast resynchronisation and for out-of-
band binary data upload/download.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8620.
Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 4
1.2. The Id Data Type . . . . . . . . . . . . . . . . . . . . 6
1.3. The Int and UnsignedInt Data Types . . . . . . . . . . . 6
1.4. The Date and UTCDate Data Types . . . . . . . . . . . . . 7
1.5. JSON as the Data Encoding Format . . . . . . . . . . . . 7
1.6. Terminology . . . . . . . . . . . . . . . . . . . . . . . 7
1.6.1. User . . . . . . . . . . . . . . . . . . . . . . . . 7
1.6.2. Accounts . . . . . . . . . . . . . . . . . . . . . . 7
1.6.3. Data Types and Records . . . . . . . . . . . . . . . 8
1.7. The JMAP API Model . . . . . . . . . . . . . . . . . . . 8
1.8. Vendor-Specific Extensions . . . . . . . . . . . . . . . 9
2. The JMAP Session Resource . . . . . . . . . . . . . . . . . . 9
2.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2. Service Autodiscovery . . . . . . . . . . . . . . . . . . 15
3. Structured Data Exchange . . . . . . . . . . . . . . . . . . 16
3.1. Making an API Request . . . . . . . . . . . . . . . . . . 16
3.2. The Invocation Data Type . . . . . . . . . . . . . . . . 16
3.3. The Request Object . . . . . . . . . . . . . . . . . . . 16
3.3.1. Example Request . . . . . . . . . . . . . . . . . . . 18
3.4. The Response Object . . . . . . . . . . . . . . . . . . . 18
3.4.1. Example Response . . . . . . . . . . . . . . . . . . 19
3.5. Omitting Arguments . . . . . . . . . . . . . . . . . . . 19
3.6. Errors . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.6.1. Request-Level Errors . . . . . . . . . . . . . . . . 20
3.6.2. Method-Level Errors . . . . . . . . . . . . . . . . . 21
3.7. References to Previous Method Results . . . . . . . . . . 22
3.8. Localisation of User-Visible Strings . . . . . . . . . . 27
3.9. Security . . . . . . . . . . . . . . . . . . . . . . . . 28
3.10. Concurrency . . . . . . . . . . . . . . . . . . . . . . . 28
4. The Core/echo Method . . . . . . . . . . . . . . . . . . . . 28
4.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . 28
5. Standard Methods and Naming Convention . . . . . . . . . . . 29
5.1. /get . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5.2. /changes . . . . . . . . . . . . . . . . . . . . . . . . 30
5.3. /set . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.4. /copy . . . . . . . . . . . . . . . . . . . . . . . . . . 40
5.5. /query . . . . . . . . . . . . . . . . . . . . . . . . . 42
5.6. /queryChanges . . . . . . . . . . . . . . . . . . . . . . 48
5.7. Examples . . . . . . . . . . . . . . . . . . . . . . . . 51
5.8. Proxy Considerations . . . . . . . . . . . . . . . . . . 58
6. Binary Data . . . . . . . . . . . . . . . . . . . . . . . . . 58
6.1. Uploading Binary Data . . . . . . . . . . . . . . . . . . 59
6.2. Downloading Binary Data . . . . . . . . . . . . . . . . . 60
6.3. Blob/copy . . . . . . . . . . . . . . . . . . . . . . . . 61
7. Push . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
7.1. The StateChange Object . . . . . . . . . . . . . . . . . 63
7.1.1. Example . . . . . . . . . . . . . . . . . . . . . . . 64
7.2. PushSubscription . . . . . . . . . . . . . . . . . . . . 64
7.2.1. PushSubscription/get . . . . . . . . . . . . . . . . 67
7.2.2. PushSubscription/set . . . . . . . . . . . . . . . . 68
7.2.3. Example . . . . . . . . . . . . . . . . . . . . . . . 69
7.3. Event Source . . . . . . . . . . . . . . . . . . . . . . 71
8. Security Considerations . . . . . . . . . . . . . . . . . . . 73
8.1. Transport Confidentiality . . . . . . . . . . . . . . . . 73
8.2. Authentication Scheme . . . . . . . . . . . . . . . . . . 73
8.3. Service Autodiscovery . . . . . . . . . . . . . . . . . . 73
8.4. JSON Parsing . . . . . . . . . . . . . . . . . . . . . . 74
8.5. Denial of Service . . . . . . . . . . . . . . . . . . . . 74
8.6. Connection to Unknown Push Server . . . . . . . . . . . . 74
8.7. Push Encryption . . . . . . . . . . . . . . . . . . . . . 75
8.8. Traffic Analysis . . . . . . . . . . . . . . . . . . . . 76
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 76
9.1. Assignment of jmap Service Name . . . . . . . . . . . . . 76
9.2. Registration of Well-Known URI Suffix for JMAP . . . . . 76
9.3. Registration of the jmap URN Sub-namespace . . . . . . . 77
9.4. Creation of "JMAP Capabilities" Registry . . . . . . . . 77
9.4.1. Preliminary Community Review . . . . . . . . . . . . 77
9.4.2. Submit Request to IANA . . . . . . . . . . . . . . . 78
9.4.3. Designated Expert Review . . . . . . . . . . . . . . 78
9.4.4. Change Procedures . . . . . . . . . . . . . . . . . . 78
9.4.5. JMAP Capabilities Registry Template . . . . . . . . . 79
9.4.6. Initial Registration for JMAP Core . . . . . . . . . 79
9.4.7. Registration for JMAP Error Placeholder in JMAP
Capabilities Registry . . . . . . . . . . . . . . . . 80
9.5. Creation of "JMAP Error Codes" Registry . . . . . . . . . 80
9.5.1. Expert Review . . . . . . . . . . . . . . . . . . . . 80
9.5.2. JMAP Error Codes Registry Template . . . . . . . . . 81
9.5.3. Initial Contents for the JMAP Error Codes Registry . 81
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 86
10.1. Normative References . . . . . . . . . . . . . . . . . . 86
10.2. Informative References . . . . . . . . . . . . . . . . . 89
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 90
1. Introduction
The JSON Meta Application Protocol (JMAP) is used for synchronising
data, such as mail, calendars, or contacts, between a client and a
server. It is optimised for mobile and web environments and aims to
provide a consistent interface to different data types.
This specification is for the generic mechanism of data
synchronisation. Further specifications define the data models for
different data types that may be synchronised via JMAP.
JMAP is designed to make efficient use of limited network resources.
Multiple API calls may be batched in a single request to the server,
reducing round trips and improving battery life on mobile devices.
Push connections remove the need for polling, and an efficient delta
update mechanism ensures a minimum amount of data is transferred.
JMAP is designed to be horizontally scalable to a very large number
of users. This is facilitated by separate endpoints for users after
login, the separation of binary and structured data, and a data model
for sharing that does not allow data dependencies between accounts.
1.1. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
The underlying format used for this specification is JSON.
Consequently, the terms "object" and "array" as well as the four
primitive types (strings, numbers, booleans, and null) are to be
interpreted as described in Section 1 of [RFC8259]. Unless otherwise
noted, all the property names and values are case sensitive.
Some examples in this document contain "partial" JSON documents used
for illustrative purposes. In these examples, three periods "..."
are used to indicate a portion of the document that has been removed
for compactness.
For compatibility with publishing requirements, line breaks have been
inserted inside long JSON strings, with the following continuation
lines indented. To form the valid JSON example, any line breaks
inside a string must be replaced with a space and any other white
space after the line break removed.
Unless otherwise specified, examples of API exchanges only show the
methodCalls array of the Request object or the methodResponses array
of the Response object. For compactness, the rest of the Request/
Response object is omitted.
Type signatures are given for all JSON values in this document. The
following conventions are used:
o "*" - The type is undefined (the value could be any type, although
permitted values may be constrained by the context of this value).
o "String" - The JSON string type.
o "Number" - The JSON number type.
o "Boolean" - The JSON boolean type.
o "A[B]" - A JSON object where the keys are all of type "A", and the
values are all of type "B".
o "A[]" - An array of values of type "A".
o "A|B" - The value is either of type "A" or of type "B".
Other types may also be given, with their representation defined
elsewhere in this document.
Object properties may also have a set of attributes defined along
with the type signature. These have the following meanings:
o "server-set" -- Only the server can set the value for this
property. The client MUST NOT send this property when creating a
new object of this type.
o "immutable" -- The value MUST NOT change after the object is
created.
o "default" -- (This is followed by a JSON value). The value that
will be used for this property if it is omitted in an argument or
when creating a new object of this type.
1.2. The Id Data Type
All record ids are assigned by the server and are immutable.
Where "Id" is given as a data type, it means a "String" of at least 1
and a maximum of 255 octets in size, and it MUST only contain
characters from the "URL and Filename Safe" base64 alphabet, as
defined in Section 5 of [RFC4648], excluding the pad character ("=").
This means the allowed characters are the ASCII alphanumeric
characters ("A-Za-z0-9"), hyphen ("-"), and underscore ("_").
These characters are safe to use in almost any context (e.g.,
filesystems, URIs, and IMAP atoms). For maximum safety, servers
SHOULD also follow defensive allocation strategies to avoid creating
risks where glob completion or data type detection may be present
(e.g., on filesystems or in spreadsheets). In particular, it is wise
to avoid:
o Ids starting with a dash
o Ids starting with digits
o Ids that contain only digits
o Ids that differ only by ASCII case (for example, A vs. a)
o the specific sequence of three characters "NIL" (because this
sequence can be confused with the IMAP protocol expression of the
null value)
A good solution to these issues is to prefix every id with a single
alphabetical character.
1.3. The Int and UnsignedInt Data Types
Where "Int" is given as a data type, it means an integer in the range
-2^53+1 <= value <= 2^53-1, the safe range for integers stored in a
floating-point double, represented as a JSON "Number".
Where "UnsignedInt" is given as a data type, it means an "Int" where
the value MUST be in the range 0 <= value <= 2^53-1.
1.4. The Date and UTCDate Data Types
Where "Date" is given as a type, it means a string in "date-time"
format [RFC3339]. To ensure a normalised form, the "time-secfrac"
MUST always be omitted if zero, and any letters in the string (e.g.,
"T" and "Z") MUST be uppercase. For example,
"2014-10-30T14:12:00+08:00".
Where "UTCDate" is given as a type, it means a "Date" where the
"time-offset" component MUST be "Z" (i.e., it must be in UTC time).
For example, "2014-10-30T06:12:00Z".
1.5. JSON as the Data Encoding Format
JSON is a text-based data interchange format as specified in
[RFC8259]. The Internet JSON (I-JSON) format defined in [RFC7493] is
a strict subset of this, adding restrictions to avoid potentially
confusing scenarios (for example, it mandates that an object MUST NOT
have two members with the same name).
All data sent from the client to the server or from the server to the
client (except binary file upload/download) MUST be valid I-JSON
according to the RFC and is therefore case sensitive and encoded in
UTF-8 [RFC3629].
1.6. Terminology
1.6.1. User
A user is a person accessing data via JMAP. A user has a set of
permissions determining the data that they can see.
1.6.2. Accounts
An account is a collection of data. A single account may contain an
arbitrary set of data types, for example, a collection of mail,
contacts, and calendars. Most JMAP methods take a mandatory
"accountId" argument that specifies on which account the operations
are to take place.
An account is not the same as a user, although it is common for a
primary account to directly belong to the user. For example, you may
have an account that contains data for a group or business, to which
multiple users have access.
A single set of credentials may provide access to multiple accounts,
for example, if another user is sharing their work calendar with the
authenticated user or if there is a group mailbox for a support-desk
inbox.
In the event of a severe internal error, a server may have to
reallocate ids or do something else that violates standard JMAP data
constraints for an account. In this situation, the data on the
server is no longer compatible with cached data the client may have
from before. The server MUST treat this as though the account has
been deleted and then recreated with a new account id. Clients will
then be forced to throw away any data with the old account id and
refetch all data from scratch.
1.6.3. Data Types and Records
JMAP provides a uniform interface for creating, retrieving, updating,
and deleting various types of objects. A "data type" is a collection
of named, typed properties, just like the schema for a database
table. Each instance of a data type is called a "record".
The id of a record is immutable and assigned by the server. The id
MUST be unique among all records of the *same type* within the *same
account*. Ids may clash across accounts or for two records of
different types within the same account.
1.7. The JMAP API Model
JMAP uses HTTP [RFC7230] to expose API, push, upload, and download
resources. All HTTP requests MUST use the "https://" scheme (HTTP
over TLS [RFC2818]). All HTTP requests MUST be authenticated.
An authenticated client can fetch the user's Session object with
details about the data and capabilities the server can provide as
shown in Section 2. The client may then exchange data with the
server in the following ways:
1. The client may make an API request to the server to get or set
structured data. This request consists of an ordered series of
method calls. These are processed by the server, which then
returns an ordered series of responses. This is described in
Sections 3, 4, and 5.
2. The client may download or upload binary files from/to the
server. This is detailed in Section 6.
3. The client may connect to a push channel on the server, to be
notified when data has changed. This is explained in Section 7.
1.8. Vendor-Specific Extensions
Individual services will have custom features they wish to expose
over JMAP. This may take the form of extra data types and/or methods
not in the spec, extra arguments to JMAP methods, or extra properties
on existing data types (which may also appear in arguments to methods
that take property names).
The server can advertise custom extensions it supports by including
the identifiers in the capabilities object. Identifiers for vendor
extensions MUST be a URL belonging to a domain owned by the vendor,
to avoid conflict. The URL SHOULD resolve to documentation for the
changes the extension makes.
The client MUST opt in to use an extension by passing the appropriate
capability identifier in the "using" array of the Request object, as
described in Section 3.3. The server MUST only follow the
specifications that are opted into and behave as though it does not
implement anything else when processing a request. This is to ensure
compatibility with clients that don't know about a specific custom
extension and for compatibility with future versions of JMAP.
2. The JMAP Session Resource
You need two things to connect to a JMAP server:
1. The URL for the JMAP Session resource. This may be requested
directly from the user or discovered automatically based on a
username domain (see Section 2.2 below).
2. Credentials to authenticate with. How to obtain credentials is
out of scope for this document.
A successful authenticated GET request to the JMAP Session resource
MUST return a JSON-encoded *Session* object, giving details about the
data and capabilities the server can provide to the client given
those credentials. It has the following properties:
o capabilities: "String[Object]"
An object specifying the capabilities of this server. Each key is
a URI for a capability supported by the server. The value for
each of these keys is an object with further information about the
server's capabilities in relation to that capability.
The client MUST ignore any properties it does not understand.
The capabilities object MUST include a property called
"urn:ietf:params:jmap:core". The value of this property is an
object that MUST contain the following information on server
capabilities (suggested minimum values for limits are supplied
that allow clients to make efficient use of the network):
* maxSizeUpload: "UnsignedInt"
The maximum file size, in octets, that the server will accept
for a single file upload (for any purpose). Suggested minimum:
50,000,000.
* maxConcurrentUpload: "UnsignedInt"
The maximum number of concurrent requests the server will
accept to the upload endpoint. Suggested minimum: 4.
* maxSizeRequest: "UnsignedInt"
The maximum size, in octets, that the server will accept for a
single request to the API endpoint. Suggested minimum:
10,000,000.
* maxConcurrentRequests: "UnsignedInt"
The maximum number of concurrent requests the server will
accept to the API endpoint. Suggested minimum: 4.
* maxCallsInRequest: "UnsignedInt"
The maximum number of method calls the server will accept in a
single request to the API endpoint. Suggested minimum: 16.
* maxObjectsInGet: "UnsignedInt"
The maximum number of objects that the client may request in a
single /get type method call. Suggested minimum: 500.
* maxObjectsInSet: "UnsignedInt"
The maximum number of objects the client may send to create,
update, or destroy in a single /set type method call. This is
the combined total, e.g., if the maximum is 10, you could not
create 7 objects and destroy 6, as this would be 13 actions,
which exceeds the limit. Suggested minimum: 500.
* collationAlgorithms: "String[]"
A list of identifiers for algorithms registered in the
collation registry, as defined in [RFC4790], that the server
supports for sorting when querying records.
Specifications for future capabilities will define their own
properties on the capabilities object.
Servers MAY advertise vendor-specific JMAP extensions, as
described in Section 1.8. To avoid conflict, an identifier for a
vendor-specific extension MUST be a URL with a domain owned by the
vendor. Clients MUST opt in to any capability it wishes to use
(see Section 3.3).
o accounts: "Id[Account]"
A map of an account id to an Account object for each account (see
Section 1.6.2) the user has access to. An *Account* object has
the following properties:
* name: "String"
A user-friendly string to show when presenting content from
this account, e.g., the email address representing the owner of
the account.
* isPersonal: "Boolean"
This is true if the account belongs to the authenticated user
rather than a group account or a personal account of another
user that has been shared with them.
* isReadOnly: "Boolean"
This is true if the entire account is read-only.
* accountCapabilities: "String[Object]"
The set of capability URIs for the methods supported in this
account. Each key is a URI for a capability that has methods
you can use with this account. The value for each of these
keys is an object with further information about the account's
permissions and restrictions with respect to this capability,
as defined in the capability's specification.
The client MUST ignore any properties it does not understand.
The server advertises the full list of capabilities it supports
in the capabilities object, as defined above. If the
capability defines new methods, the server MUST include it in
the accountCapabilities object if the user may use those
methods with this account. It MUST NOT include it in the
accountCapabilities object if the user cannot use those methods
with this account.
For example, you may have access to your own account with mail,
calendars, and contacts data and also a shared account that
only has contacts data (a business address book, for example).
In this case, the accountCapabilities property on the first
account would include something like
"urn:ietf:params:jmap:mail", "urn:ietf:params:jmap:calendars",
and "urn:ietf:params:jmap:contacts", while the second account
would just have the last of these.
Attempts to use the methods defined in a capability with one of
the accounts that does not support that capability are rejected
with an "accountNotSupportedByMethod" error (see "Method-Level
Errors", Section 3.6.2).
o primaryAccounts: "String[Id]"
A map of capability URIs (as found in accountCapabilities) to the
account id that is considered to be the user's main or default
account for data pertaining to that capability. If no account
being returned belongs to the user, or in any other way there is
no appropriate way to determine a default account, there MAY be no
entry for a particular URI, even though that capability is
supported by the server (and in the capabilities object).
"urn:ietf:params:jmap:core" SHOULD NOT be present.
o username: "String"
The username associated with the given credentials, or the empty
string if none.
o apiUrl: "String"
The URL to use for JMAP API requests.
o downloadUrl: "String"
The URL endpoint to use when downloading files, in URI Template
(level 1) format [RFC6570]. The URL MUST contain variables called
"accountId", "blobId", "type", and "name". The use of these
variables is described in Section 6.2. Due to potential encoding
issues with slashes in content types, it is RECOMMENDED to put the
"type" variable in the query section of the URL.
o uploadUrl: "String"
The URL endpoint to use when uploading files, in URI Template
(level 1) format [RFC6570]. The URL MUST contain a variable
called "accountId". The use of this variable is described in
Section 6.1.
o eventSourceUrl: "String"
The URL to connect to for push events, as described in
Section 7.3, in URI Template (level 1) format [RFC6570]. The URL
MUST contain variables called "types", "closeafter", and "ping".
The use of these variables is described in Section 7.3.
o state: "String"
A (preferably short) string representing the state of this object
on the server. If the value of any other property on the Session
object changes, this string will change. The current value is
also returned on the API Response object (see Section 3.4),
allowing clients to quickly determine if the session information
has changed (e.g., an account has been added or removed), so they
need to refetch the object.
To ensure future compatibility, other properties MAY be included on
the Session object. Clients MUST ignore any properties they are not
expecting.
Implementors must take care to avoid inappropriate caching of the
Session object at the HTTP layer. Since the client should only
refetch when it detects there is a change (via the sessionState
property of an API response), it is RECOMMENDED to disable HTTP
caching altogether, for example, by setting "Cache-Control: no-cache,
no-store, must-revalidate" on the response.
2.1. Example
In the following example Session object, the user has access to their
own mail and contacts via JMAP, as well as read-only access to shared
mail from another user. The server is advertising a custom
"https://example.com/apis/foobar" capability.
{
"capabilities": {
"urn:ietf:params:jmap:core": {
"maxSizeUpload": 50000000,
"maxConcurrentUpload": 8,
"maxSizeRequest": 10000000,
"maxConcurrentRequest": 8,
"maxCallsInRequest": 32,
"maxObjectsInGet": 256,
"maxObjectsInSet": 128,
"collationAlgorithms": [
"i;ascii-numeric",
"i;ascii-casemap",
"i;unicode-casemap"
]
},
"urn:ietf:params:jmap:mail": {}
"urn:ietf:params:jmap:contacts": {},
"https://example.com/apis/foobar": {
"maxFoosFinangled": 42
}
},
"accounts": {
"A13824": {
"name": "john@example.com",
"isPersonal": true,
"isReadOnly": false,
"accountCapabilities": {
"urn:ietf:params:jmap:mail": {
"maxMailboxesPerEmail": null,
"maxMailboxDepth": 10,
...
},
"urn:ietf:params:jmap:contacts": {
...
}
}
},
"A97813": {
"name": "jane@example.com",
"isPersonal": false,
"isReadOnly": true,
"accountCapabilities": {
"urn:ietf:params:jmap:mail": {
"maxMailboxesPerEmail": 1,
"maxMailboxDepth": 10,
...
}
}
}
},
"primaryAccounts": {
"urn:ietf:params:jmap:mail": "A13824",
"urn:ietf:params:jmap:contacts": "A13824"
},
"username": "john@example.com",
"apiUrl": "https://jmap.example.com/api/",
"downloadUrl": "https://jmap.example.com
/download/{accountId}/{blobId}/{name}?accept={type}",
"uploadUrl": "https://jmap.example.com/upload/{accountId}/",
"eventSourceUrl": "https://jmap.example.com
/eventsource/?types={types}&closeafter={closeafter}&ping={ping}",
"state": "75128aab4b1b"
}
2.2. Service Autodiscovery
There are two standardised autodiscovery methods in use for Internet
protocols:
o DNS SRV (see [RFC2782], [RFC6186], and [RFC6764])
o .well-known/servicename (see [RFC8615])
A JMAP-supporting host for the domain "example.com" SHOULD publish a
SRV record "_jmap._tcp.example.com" that gives a hostname and port
(usually port "443"). The JMAP Session resource is then
"https://${hostname}[:${port}]/.well-known/jmap" (following any
redirects).
If the client has a username in the form of an email address, it MAY
use the domain portion of this to attempt autodiscovery of the JMAP
server.
3. Structured Data Exchange
The client may make an API request to the server to get or set
structured data. This request consists of an ordered series of
method calls. These are processed by the server, which then returns
an ordered series of responses.
3.1. Making an API Request
To make an API request, the client makes an authenticated POST
request to the API resource, which is defined by the "apiUrl"
property in the Session object (see Section 2).
The request MUST be of type "application/json" and consist of a
single JSON-encoded "Request" object, as defined in Section 3.3. If
successful, the response MUST also be of type "application/json" and
consist of a single "Response" object, as defined in Section 3.4.
3.2. The Invocation Data Type
Method calls and responses are represented by the *Invocation* data
type. This is a tuple, represented as a JSON array containing three
elements:
1. A "String" *name* of the method to call or of the response.
2. A "String[*]" object containing named *arguments* for that method
or response.
3. A "String" *method call id*: an arbitrary string from the client
to be echoed back with the responses emitted by that method call
(a method may return 1 or more responses, as it may make implicit
calls to other methods; all responses initiated by this method
call get the same method call id in the response).
3.3. The Request Object
A *Request* object has the following properties:
o using: "String[]"
The set of capabilities the client wishes to use. The client MAY
include capability identifiers even if the method calls it makes
do not utilise those capabilities. The server advertises the set
of specifications it supports in the Session object (see
Section 2), as keys on the "capabilities" property.
o methodCalls: "Invocation[]"
An array of method calls to process on the server. The method
calls MUST be processed sequentially, in order.
o createdIds: "Id[Id]" (optional)
A map of a (client-specified) creation id to the id the server
assigned when a record was successfully created.
As described later in this specification, some records may have a
property that contains the id of another record. To allow more
efficient network usage, you can set this property to reference a
record created earlier in the same API request. Since the real id
is unknown when the request is created, the client can instead
specify the creation id it assigned, prefixed with a "#" (see
Section 5.3 for more details).
As the server processes API requests, any time it successfully
creates a new record, it adds the creation id to this map (see the
"create" argument to /set in Section 5.3), with the server-
assigned real id as the value. If it comes across a reference to
a creation id in a create/update, it looks it up in the map and
replaces the reference with the real id, if found.
The client can pass an initial value for this map as the
"createdIds" property of the Request object. This may be an empty
object. If given in the request, the response will also include a
createdIds property. This allows proxy servers to easily split a
JMAP request into multiple JMAP requests to send to different
servers. For example, it could send the first two method calls to
server A, then the third to server B, before sending the fourth to
server A again. By passing the createdIds of the previous
response to the next request, it can ensure all of these still
resolve. See Section 5.8 for further discussion of proxy
considerations.
Future specifications MAY add further properties to the Request
object to extend the semantics. To ensure forwards compatibility, a
server MUST ignore any other properties it does not understand on the
JMAP Request object.
3.3.1. Example Request
{
"using": [ "urn:ietf:params:jmap:core", "urn:ietf:params:jmap:mail" ],
"methodCalls": [
[ "method1", {
"arg1": "arg1data",
"arg2": "arg2data"
}, "c1" ],
[ "method2", {
"arg1": "arg1data"
}, "c2" ],
[ "method3", {}, "c3" ]
]
}
3.4. The Response Object
A *Response* object has the following properties:
o methodResponses: "Invocation[]"
An array of responses, in the same format as the "methodCalls" on
the Request object. The output of the methods MUST be added to
the "methodResponses" array in the same order that the methods are
processed.
o createdIds: "Id[Id]" (optional; only returned if given in the
request)
A map of a (client-specified) creation id to the id the server
assigned when a record was successfully created. This MUST
include all creation ids passed in the original createdIds
parameter of the Request object, as well as any additional ones
added for newly created records.
o sessionState: "String"
The current value of the "state" string on the Session object, as
described in Section 2. Clients may use this to detect if this
object has changed and needs to be refetched.
Unless otherwise specified, if the method call completed
successfully, its response name is the same as the method name in the
request.
3.4.1. Example Response
{
"methodResponses": [
[ "method1", {
"arg1": 3,
"arg2": "foo"
}, "c1" ],
[ "method2", {
"isBlah": true
}, "c2" ],
[ "anotherResponseFromMethod2", {
"data": 10,
"yetmoredata": "Hello"
}, "c2"],
[ "error", {
"type":"unknownMethod"
}, "c3" ]
],
"sessionState": "75128aab4b1b"
}
3.5. Omitting Arguments
An argument to a method may be specified to have a default value. If
omitted by the client, the server MUST treat the method call the same
as if the default value had been specified. Similarly, the server
MAY omit any argument in a response that has the default value.
Unless otherwise specified in a method description, null is the
default value for any argument in a request or response where this is
allowed by the type signature. Other arguments may only be omitted
if an explicit default value is defined in the method description.
3.6. Errors
There are three different levels of granularity at which an error may
be returned in JMAP.
When an API request is made, the request as a whole may be rejected
due to rate limiting, malformed JSON, request for an unknown
capability, etc. In this case, the entire request is rejected with
an appropriate HTTP error response code and an additional JSON body
with more detail for the client.
Provided the request itself is syntactically valid (the JSON is valid
and when decoded, it matches the type signature of a Request object),
the methods within it are executed sequentially by the server. Each
method may individually fail, for example, if invalid arguments are
given or an unknown method name is called.
Finally, methods that make changes to the server state often act upon
a number of different records within a single call. Each record
change may be separately rejected with a SetError, as described in
Section 5.3.
3.6.1. Request-Level Errors
When an HTTP error response is returned to the client, the server
SHOULD return a JSON "problem details" object as the response body,
as per [RFC7807].
The following problem types are defined:
o "urn:ietf:params:jmap:error:unknownCapability"
The client included a capability in the "using" property of the
request that the server does not support.
o "urn:ietf:params:jmap:error:notJSON"
The content type of the request was not "application/json" or the
request did not parse as I-JSON.
o "urn:ietf:params:jmap:error:notRequest"
The request parsed as JSON but did not match the type signature of
the Request object.
o "urn:ietf:params:jmap:error:limit"
The request was not processed as it would have exceeded one of the
request limits defined on the capability object, such as
maxSizeRequest, maxCallsInRequest, or maxConcurrentRequests. A
"limit" property MUST also be present on the "problem details"
object, containing the name of the limit being applied.
3.6.1.1. Example
{
"type": "urn:ietf:params:jmap:error:unknownCapability",
"status": 400,
"detail": "The Request object used capability
'https://example.com/apis/foobar', which is not supported
by this server."
}
Another example:
{
"type": "urn:ietf:params:jmap:error:limit",
"limit": "maxSizeRequest",
"status": 400,
"detail": "The request is larger than the server is willing to
process."
}
3.6.2. Method-Level Errors
If a method encounters an error, the appropriate "error" response
MUST be inserted at the current point in the "methodResponses" array
and, unless otherwise specified, further processing MUST NOT happen
within that method call.
Any further method calls in the request MUST then be processed as
normal. Errors at the method level MUST NOT generate an HTTP-level
error.
An "error" response looks like this:
[ "error", {
"type": "unknownMethod"
}, "call-id" ]
The response name is "error", and it MUST have a type property.
Other properties may be present with further information; these are
detailed in the error type descriptions where appropriate.
With the exception of when the "serverPartialFail" error is returned,
the externally visible state of the server MUST NOT have changed if
an error is returned at the method level.
The following error types are defined, which may be returned for any
method call where appropriate:
"serverUnavailable": Some internal server resource was temporarily
unavailable. Attempting the same operation later (perhaps after a
backoff with a random factor) may succeed.
"serverFail": An unexpected or unknown error occurred during the
processing of the call. A "description" property should provide more
details about the error. The method call made no changes to the
server's state. Attempting the same operation again is expected to
fail again. Contacting the service administrator is likely necessary
to resolve this problem if it is persistent.
"serverPartialFail": Some, but not all, expected changes described by
the method occurred. The client MUST resynchronise impacted data to
determine server state. Use of this error is strongly discouraged.
"unknownMethod": The server does not recognise this method name.
"invalidArguments": One of the arguments is of the wrong type or is
otherwise invalid, or a required argument is missing. A
"description" property MAY be present to help debug with an
explanation of what the problem was. This is a non-localised string,
and it is not intended to be shown directly to end users.
"invalidResultReference": The method used a result reference for one
of its arguments (see Section 3.7), but this failed to resolve.
"forbidden": The method and arguments are valid, but executing the
method would violate an Access Control List (ACL) or other
permissions policy.
"accountNotFound": The accountId does not correspond to a valid
account.
"accountNotSupportedByMethod": The accountId given corresponds to a
valid account, but the account does not support this method or data
type.
"accountReadOnly": This method modifies state, but the account is
read-only (as returned on the corresponding Account object in the
JMAP Session resource).
Further possible errors for a particular method are specified in the
method descriptions.
Further general errors MAY be defined in future RFCs. Should a
client receive an error type it does not understand, it MUST treat it
the same as the "serverFail" type.
3.7. References to Previous Method Results
To allow clients to make more efficient use of the network and avoid
round trips, an argument to one method can be taken from the result
of a previous method call in the same request.
To do this, the client prefixes the argument name with "#" (an
octothorpe). The value is a ResultReference object as described
below. When processing a method call, the server MUST first check
the arguments object for any names beginning with "#". If found, the
result reference should be resolved and the value used as the "real"
argument. The method is then processed as normal. If any result
reference fails to resolve, the whole method MUST be rejected with an
"invalidResultReference" error. If an arguments object contains the
same argument name in normal and referenced form (e.g., "foo" and
"#foo"), the method MUST return an "invalidArguments" error.
A *ResultReference* object has the following properties:
o resultOf: "String"
The method call id (see Section 3.2) of a previous method call in
the current request.
o name: "String"
The required name of a response to that method call.
o path: "String"
A pointer into the arguments of the response selected via the name
and resultOf properties. This is a JSON Pointer [RFC6901], except
it also allows the use of "*" to map through an array (see the
description below).
To resolve:
1. Find the first response with a method call id identical to the
"resultOf" property of the ResultReference in the
"methodResponses" array from previously processed method calls in
the same request. If none, evaluation fails.
2. If the response name is not identical to the "name" property of
the ResultReference, evaluation fails.
3. Apply the "path" to the arguments object of the response (the
second item in the response array) following the JSON Pointer
algorithm [RFC6901], except with the following addition in
"Evaluation" (see Section 4):
If the currently referenced value is a JSON array, the reference
token may be exactly the single character "*", making the new
referenced value the result of applying the rest of the JSON
Pointer tokens to every item in the array and returning the
results in the same order in a new array. If the result of
applying the rest of the pointer tokens to each item was itself
an array, the contents of this array are added to the output
rather than the array itself (i.e., the result is flattened from
an array of arrays to a single array). If the result of applying
the rest of the pointer tokens to a value was itself an array,
its items should be included individually in the output rather
than including the array itself (i.e., the result is flattened
from an array of arrays to a single array).
As a simple example, suppose we have the following API request
"methodCalls":
[[ "Foo/changes", {
"accountId": "A1",
"sinceState": "abcdef"
}, "t0" ],
[ "Foo/get", {
"accountId": "A1",
"#ids": {
"resultOf": "t0",
"name": "Foo/changes",
"path": "/created"
}
}, "t1" ]]
After executing the first method call, the "methodResponses" array
is:
[[ "Foo/changes", {
"accountId": "A1",
"oldState": "abcdef",
"newState": "123456",
"hasMoreChanges": false,
"created": [ "f1", "f4" ],
"updated": [],
"destroyed": []
}, "t0" ]]
To execute the "Foo/get" call, we look through the arguments and find
there is one with a "#" prefix. To resolve this, we apply the
algorithm above:
1. Find the first response with method call id "t0". The "Foo/
changes" response fulfils this criterion.
2. Check that the response name is the same as in the result
reference. It is, so this is fine.
3. Apply the "path" as a JSON Pointer to the arguments object. This
simply selects the "created" property, so the result of
evaluating is: [ "f1", "f4" ].
The JMAP server now continues to process the "Foo/get" call as though
the arguments were:
{
"accountId": "A1",
"ids": [ "f1", "f4" ]
}
Now, a more complicated example using the JMAP Mail data model: fetch
the "from"/"date"/"subject" for every Email in the first 10 Threads
in the inbox (sorted newest first):
[[ "Email/query", {
"accountId": "A1",
"filter": { "inMailbox": "id_of_inbox" },
"sort": [{ "property": "receivedAt", "isAscending": false }],
"collapseThreads": true,
"position": 0,
"limit": 10,
"calculateTotal": true
}, "t0" ],
[ "Email/get", {
"accountId": "A1",
"#ids": {
"resultOf": "t0",
"name": "Email/query",
"path": "/ids"
},
"properties": [ "threadId" ]
}, "t1" ],
[ "Thread/get", {
"accountId": "A1",
"#ids": {
"resultOf": "t1",
"name": "Email/get",
"path": "/list/*/threadId"
}
}, "t2" ],
[ "Email/get", {
"accountId": "A1",
"#ids": {
"resultOf": "t2",
"name": "Thread/get",
"path": "/list/*/emailIds"
},
"properties": [ "from", "receivedAt", "subject" ]
}, "t3" ]]
After executing the first 3 method calls, the "methodResponses" array
might be:
[[ "Email/query", {
"accountId": "A1",
"queryState": "abcdefg",
"canCalculateChanges": true,
"position": 0,
"total": 101,
"ids": [ "msg1023", "msg223", "msg110", "msg93", "msg91",
"msg38", "msg36", "msg33", "msg11", "msg1" ]
}, "t0" ],
[ "Email/get", {
"accountId": "A1",
"state": "123456",
"list": [{
"id": "msg1023",
"threadId": "trd194"
}, {
"id": "msg223",
"threadId": "trd114"
},
...
],
"notFound": []
}, "t1" ],
[ "Thread/get", {
"accountId": "A1",
"state": "123456",
"list": [{
"id": "trd194",
"emailIds": [ "msg1020", "msg1021", "msg1023" ]
}, {
"id": "trd114",
"emailIds": [ "msg201", "msg223" ]
},
...
],
"notFound": []
}, "t2" ]]
To execute the final "Email/get" call, we look through the arguments
and find there is one with a "#" prefix. To resolve this, we apply
the algorithm:
1. Find the first response with method call id "t2". The "Thread/
get" response fulfils this criterion.
2. "Thread/get" is the name specified in the result reference, so
this is fine.
3. Apply the "path" as a JSON Pointer to the arguments object.
Token by token:
1. "list": get the array of thread objects
2. "*": for each of the items in the array:
a. "emailIds": get the array of Email ids
b. Concatenate these into a single array of all the ids in
the result.
The JMAP server now continues to process the "Email/get" call as
though the arguments were:
{
"accountId": "A1",
"ids": [ "msg1020", "msg1021", "msg1023", "msg201", "msg223", ... ],
"properties": [ "from", "receivedAt", "subject" ]
}
The ResultReference performs a similar role to that of the creation
id, in that it allows a chained method call to refer to information
not available when the request is generated. However, they are
different things and not interchangeable; the only commonality is the
octothorpe used to indicate them.
3.8. Localisation of User-Visible Strings
If returning a custom string to be displayed to the user, for
example, an error message, the server SHOULD use information from the
Accept-Language header of the request (as defined in Section 5.3.5 of
[RFC7231]) to choose the best available localisation. The Content-
Language header of the response (see Section 3.1.3.2 of [RFC7231])
SHOULD indicate the language being used for user-visible strings.
For example, suppose a request was made with the following header:
Accept-Language: fr-CH, fr;q=0.9, de;q=0.8, en;q=0.7, *;q=0.5
and a method generated an error to display to the user. The server
has translations of the error message in English and German. Looking
at the Accept-Language header, the user's preferred language is
French. Since we don't have a translation for this, we look at the
next most preferred, which is German. We have a German translation,
so the server returns this and indicates the language chosen in a
Content-Language header like so:
Content-Language: de
3.9. Security
As always, the server must be strict about data received from the
client. Arguments need to be checked for validity; a malicious user
could attempt to find an exploit through the API. In case of invalid
arguments (unknown/insufficient/wrong type for data, etc.), the
method MUST return an "invalidArguments" error and terminate.
3.10. Concurrency
Method calls within a single request MUST be executed in order.
However, method calls from different concurrent API requests may be
interleaved. This means that the data on the server may change
between two method calls within a single API request.
4. The Core/echo Method
The "Core/echo" method returns exactly the same arguments as it is
given. It is useful for testing if you have a valid authenticated
connection to a JMAP API endpoint.
4.1. Example
Request:
[[ "Core/echo", {
"hello": true,
"high": 5
}, "b3ff" ]]
Response:
[[ "Core/echo", {
"hello": true,
"high": 5
}, "b3ff" ]]
5. Standard Methods and Naming Convention
JMAP provides a uniform interface for creating, retrieving, updating,
and deleting objects of a particular type. For a "Foo" data type,
records of that type would be fetched via a "Foo/get" call and
modified via a "Foo/set" call. Delta updates may be fetched via a
"Foo/changes" call. These methods all follow a standard format as
described below.
Some types may not have all these methods. Specifications defining
types MUST specify which methods are available for the type.
5.1. /get
Objects of type Foo are fetched via a call to "Foo/get".
It takes the following arguments:
o accountId: "Id"
The id of the account to use.
o ids: "Id[]|null"
The ids of the Foo objects to return. If null, then *all* records
of the data type are returned, if this is supported for that data
type and the number of records does not exceed the
"maxObjectsInGet" limit.
o properties: "String[]|null"
If supplied, only the properties listed in the array are returned
for each Foo object. If null, all properties of the object are
returned. The id property of the object is *always* returned,
even if not explicitly requested. If an invalid property is
requested, the call MUST be rejected with an "invalidArguments"
error.
The response has the following arguments:
o accountId: "Id"
The id of the account used for the call.
o state: "String"
A (preferably short) string representing the state on the server
for *all* the data of this type in the account (not just the
objects returned in this call). If the data changes, this string
MUST change. If the Foo data is unchanged, servers SHOULD return
the same state string on subsequent requests for this data type.
When a client receives a response with a different state string to
a previous call, it MUST either throw away all currently cached
objects for the type or call "Foo/changes" to get the exact
changes.
o list: "Foo[]"
An array of the Foo objects requested. This is the *empty array*
if no objects were found or if the "ids" argument passed in was
also an empty array. The results MAY be in a different order to
the "ids" in the request arguments. If an identical id is
included more than once in the request, the server MUST only
include it once in either the "list" or the "notFound" argument of
the response.
o notFound: "Id[]"
This array contains the ids passed to the method for records that
do not exist. The array is empty if all requested ids were found
or if the "ids" argument passed in was either null or an empty
array.
The following additional error may be returned instead of the "Foo/
get" response:
"requestTooLarge": The number of ids requested by the client exceeds
the maximum number the server is willing to process in a single
method call.
5.2. /changes
When the state of the set of Foo records in an account changes on the
server (whether due to creation, updates, or deletion), the "state"
property of the "Foo/get" response will change. The "Foo/changes"
method allows a client to efficiently update the state of its Foo
cache to match the new state on the server. It takes the following
arguments:
o accountId: "Id"
The id of the account to use.
o sinceState: "String"
The current state of the client. This is the string that was
returned as the "state" argument in the "Foo/get" response. The
server will return the changes that have occurred since this
state.
o maxChanges: "UnsignedInt|null"
The maximum number of ids to return in the response. The server
MAY choose to return fewer than this value but MUST NOT return
more. If not given by the client, the server may choose how many
to return. If supplied by the client, the value MUST be a
positive integer greater than 0. If a value outside of this range
is given, the server MUST reject the call with an
"invalidArguments" error.
The response has the following arguments:
o accountId: "Id"
The id of the account used for the call.
o oldState: "String"
This is the "sinceState" argument echoed back; it's the state from
which the server is returning changes.
o newState: "String"
This is the state the client will be in after applying the set of
changes to the old state.
o hasMoreChanges: "Boolean"
If true, the client may call "Foo/changes" again with the
"newState" returned to get further updates. If false, "newState"
is the current server state.
o created: "Id[]"
An array of ids for records that have been created since the old
state.
o updated: "Id[]"
An array of ids for records that have been updated since the old
state.
o destroyed: "Id[]"
An array of ids for records that have been destroyed since the old
state.
If a record has been created AND updated since the old state, the
server SHOULD just return the id in the "created" list but MAY return
it in the "updated" list as well.
If a record has been updated AND destroyed since the old state, the
server SHOULD just return the id in the "destroyed" list but MAY
return it in the "updated" list as well.
If a record has been created AND destroyed since the old state, the
server SHOULD remove the id from the response entirely. However, it
MAY include it in just the "destroyed" list or in both the
"destroyed" and "created" lists.
If a "maxChanges" is supplied, or set automatically by the server,
the server MUST ensure the number of ids returned across "created",
"updated", and "destroyed" does not exceed this limit. If there are
more changes than this between the client's state and the current
server state, the server SHOULD generate an update to take the client
to an intermediate state, from which the client can continue to call
"Foo/changes" until it is fully up to date. If it is unable to
calculate an intermediate state, it MUST return a
"cannotCalculateChanges" error response instead.
When generating intermediate states, the server may choose how to
divide up the changes. For many types, it will provide a better user
experience to return the more recent changes first, as this is more
likely to be what the user is most interested in. The client can
then continue to page in the older changes while the user is viewing
the newer data. For example, suppose a server went through the
following states:
A -> B -> C -> D -> E
And a client asks for changes from state "B". The server might first
get the ids of records created, updated, or destroyed between states
D and E, returning them with:
state: "B-D-E"
hasMoreChanges: true
The client will then ask for the change from state "B-D-E", and the
server can return the changes between states C and D, returning:
state: "B-C-E"
hasMoreChanges: true
Finally, the client will request the changes from "B-C-E", and the
server can return the changes between states B and C, returning:
state: "E"
hasMoreChanges: false
Should the state on the server be modified in the middle of all this
(to "F"), the server still does the same, but now when the update to
state "E" is returned, it would indicate that it still has more
changes for the client to fetch.
Where multiple changes to a record are split across different
intermediate states, the server MUST NOT return a record as created
after a response that deems it as updated or destroyed, and it MUST
NOT return a record as destroyed before a response that deems it as
created or updated. The server may have to coalesce multiple changes
to a record to satisfy this requirement.
The following additional errors may be returned instead of the "Foo/
changes" response:
"cannotCalculateChanges": The server cannot calculate the changes
from the state string given by the client. Usually, this is due to
the client's state being too old or the server being unable to
produce an update to an intermediate state when there are too many
updates. The client MUST invalidate its Foo cache.
Maintaining state to allow calculation of "Foo/changes" can be
expensive for the server, but always returning
"cannotCalculateChanges" severely increases network traffic and
resource usage for the client. To allow efficient sync, servers
SHOULD be able to calculate changes from any state string that was
given to a client within the last 30 days (but of course may support
calculating updates from states older than this).
5.3. /set
Modifying the state of Foo objects on the server is done via the
"Foo/set" method. This encompasses creating, updating, and
destroying Foo records. This allows the server to sort out ordering
and dependencies that may exist if doing multiple operations at once
(for example, to ensure there is always a minimum number of a certain
record type).
The "Foo/set" method takes the following arguments:
o accountId: "Id"
The id of the account to use.
o ifInState: "String|null"
This is a state string as returned by the "Foo/get" method
(representing the state of all objects of this type in the
account). If supplied, the string must match the current state;
otherwise, the method will be aborted and a "stateMismatch" error
returned. If null, any changes will be applied to the current
state.
o create: "Id[Foo]|null"
A map of a *creation id* (a temporary id set by the client) to Foo
objects, or null if no objects are to be created.
The Foo object type definition may define default values for
properties. Any such property may be omitted by the client.
The client MUST omit any properties that may only be set by the
server (for example, the "id" property on most object types).
o update: "Id[PatchObject]|null"
A map of an id to a Patch object to apply to the current Foo
object with that id, or null if no objects are to be updated.
A *PatchObject* is of type "String[*]" and represents an unordered
set of patches. The keys are a path in JSON Pointer format
[RFC6901], with an implicit leading "/" (i.e., prefix each key
with "/" before applying the JSON Pointer evaluation algorithm).
All paths MUST also conform to the following restrictions; if
there is any violation, the update MUST be rejected with an
"invalidPatch" error:
* The pointer MUST NOT reference inside an array (i.e., you MUST
NOT insert/delete from an array; the array MUST be replaced in
its entirety instead).
* All parts prior to the last (i.e., the value after the final
slash) MUST already exist on the object being patched.
* There MUST NOT be two patches in the PatchObject where the
pointer of one is the prefix of the pointer of the other, e.g.,
"alerts/1/offset" and "alerts".
The value associated with each pointer determines how to apply
that patch:
* If null, set to the default value if specified for this
property; otherwise, remove the property from the patched
object. If the key is not present in the parent, this a no-op.
* Anything else: The value to set for this property (this may be
a replacement or addition to the object being patched).
Any server-set properties MAY be included in the patch if their
value is identical to the current server value (before applying
the patches to the object). Otherwise, the update MUST be
rejected with an "invalidProperties" SetError.
This patch definition is designed such that an entire Foo object
is also a valid PatchObject. The client may choose to optimise
network usage by just sending the diff or may send the whole
object; the server processes it the same either way.
o destroy: "Id[]|null"
A list of ids for Foo objects to permanently delete, or null if no
objects are to be destroyed.
Each creation, modification, or destruction of an object is
considered an atomic unit. It is permissible for the server to
commit changes to some objects but not others; however, it MUST NOT
only commit part of an update to a single record (e.g., update a
"name" property but not a "count" property, if both are supplied in
the update object).
The final state MUST be valid after the "Foo/set" is finished;
however, the server may have to transition through invalid
intermediate states (not exposed to the client) while processing the
individual create/update/destroy requests. For example, suppose
there is a "name" property that must be unique. A single method call
could rename an object A => B and simultaneously rename another
object B => A. If the final state is valid, this is allowed.
Otherwise, each creation, modification, or destruction of an object
should be processed sequentially and accepted/rejected based on the
current server state.
If a create, update, or destroy is rejected, the appropriate error
MUST be added to the notCreated/notUpdated/notDestroyed property of
the response, and the server MUST continue to the next create/update/
destroy. It does not terminate the method.
If an id given cannot be found, the update or destroy MUST be
rejected with a "notFound" set error.
The server MAY skip an update (rejecting it with a "willDestroy"
SetError) if that object is destroyed in the same /set request.
Some records may hold references to other records (foreign keys).
That reference may be set (via create or update) in the same request
as the referenced record is created. To do this, the client refers
to the new record using its creation id prefixed with a "#". The
order of the method calls in the request by the client MUST be such
that the record being referenced is created in the same or an earlier
call. Thus, the server never has to look ahead. Instead, while
processing a request, the server MUST keep a simple map for the
duration of the request of creation id to record id for each newly
created record, so it can substitute in the correct value if
necessary in later method calls. In the case of records with
references to the same type, the server MUST order the creates and
updates within a single method call so that creates happen before
their creation ids are referenced by another create/update/destroy in
the same call.
Creation ids are not scoped by type but are a single map for all
types. A client SHOULD NOT reuse a creation id anywhere in the same
API request. If a creation id is reused, the server MUST map the
creation id to the most recently created item with that id. To allow
easy proxying of API requests, an initial set of creation id to real
id values may be passed with a request (see "The Request Object",
Section 3.3) and the final state of the map passed out with the
response (see "The Response Object", Section 3.4).
The response has the following arguments:
o accountId: "Id"
The id of the account used for the call.
o oldState: "String|null"
The state string that would have been returned by "Foo/get" before
making the requested changes, or null if the server doesn't know
what the previous state string was.
o newState: "String"
The state string that will now be returned by "Foo/get".
o created: "Id[Foo]|null"
A map of the creation id to an object containing any properties of
the created Foo object that were not sent by the client. This
includes all server-set properties (such as the "id" in most
object types) and any properties that were omitted by the client
and thus set to a default by the server.
This argument is null if no Foo objects were successfully created.
o updated: "Id[Foo|null]|null"
The keys in this map are the ids of all Foos that were
successfully updated.
The value for each id is a Foo object containing any property that
changed in a way *not* explicitly requested by the PatchObject
sent to the server, or null if none. This lets the client know of
any changes to server-set or computed properties.
This argument is null if no Foo objects were successfully updated.
o destroyed: "Id[]|null"
A list of Foo ids for records that were successfully destroyed, or
null if none.
o notCreated: "Id[SetError]|null"
A map of the creation id to a SetError object for each record that
failed to be created, or null if all successful.
o notUpdated: "Id[SetError]|null"
A map of the Foo id to a SetError object for each record that
failed to be updated, or null if all successful.
o notDestroyed: "Id[SetError]|null"
A map of the Foo id to a SetError object for each record that
failed to be destroyed, or null if all successful.
A *SetError* object has the following properties:
o type: "String"
The type of error.
o description: "String|null"
A description of the error to help with debugging that includes an
explanation of what the problem was. This is a non-localised
string and is not intended to be shown directly to end users.
The following SetError types are defined and may be returned for set
operations on any record type where appropriate:
o "forbidden": (create; update; destroy). The create/update/destroy
would violate an ACL or other permissions policy.
o "overQuota": (create; update). The create would exceed a server-
defined limit on the number or total size of objects of this type.
o "tooLarge": (create; update). The create/update would result in
an object that exceeds a server-defined limit for the maximum size
of a single object of this type.
o "rateLimit": (create). Too many objects of this type have been
created recently, and a server-defined rate limit has been
reached. It may work if tried again later.
o "notFound": (update; destroy). The id given to update/destroy
cannot be found.
o "invalidPatch": (update). The PatchObject given to update the
record was not a valid patch (see the patch description).
o "willDestroy": (update). The client requested that an object be
both updated and destroyed in the same /set request, and the
server has decided to therefore ignore the update.
o "invalidProperties": (create; update). The record given is
invalid in some way. For example:
* It contains properties that are invalid according to the type
specification of this record type.
* It contains a property that may only be set by the server
(e.g., "id") and is different to the current value. Note, to
allow clients to pass whole objects back, it is not an error to
include a server-set property in an update as long as the value
is identical to the current value on the server.
* There is a reference to another record (foreign key), and the
given id does not correspond to a valid record.
The SetError object SHOULD also have a property called
"properties" of type "String[]" that lists *all* the properties
that were invalid.
Individual methods MAY specify more specific errors for certain
conditions that would otherwise result in an invalidProperties
error. If the condition of one of these is met, it MUST be
returned instead of the invalidProperties error.
o "singleton": (create; destroy). This is a singleton type, so you
cannot create another one or destroy the existing one.
Other possible SetError types MAY be given in specific method
descriptions. Other properties MAY also be present on the SetError
object, as described in the relevant methods.
The following additional errors may be returned instead of the "Foo/
set" response:
"requestTooLarge": The total number of objects to create, update, or
destroy exceeds the maximum number the server is willing to process
in a single method call.
"stateMismatch": An "ifInState" argument was supplied, and it does
not match the current state.
5.4. /copy
The only way to move Foo records *between* two different accounts is
to copy them using the "Foo/copy" method; once the copy has
succeeded, delete the original. The "onSuccessDestroyOriginal"
argument allows you to try to do this in one method call; however,
note that the two different actions are not atomic, so it is possible
for the copy to succeed but the original not to be destroyed for some
reason.
The copy is conceptually in three phases:
1. Reading the current values from the "from" account.
2. Writing the new copies to the other account.
3. Destroying the originals in the "from" account, if requested.
Data may change in between phases due to concurrent requests.
The "Foo/copy" method takes the following arguments:
o fromAccountId: "Id"
The id of the account to copy records from.
o ifFromInState: "String|null"
This is a state string as returned by the "Foo/get" method. If
supplied, the string must match the current state of the account
referenced by the fromAccountId when reading the data to be
copied; otherwise, the method will be aborted and a
"stateMismatch" error returned. If null, the data will be read
from the current state.
o accountId: "Id"
The id of the account to copy records to. This MUST be different
to the "fromAccountId".
o ifInState: "String|null"
This is a state string as returned by the "Foo/get" method. If
supplied, the string must match the current state of the account
referenced by the accountId; otherwise, the method will be aborted
and a "stateMismatch" error returned. If null, any changes will
be applied to the current state.
o create: "Id[Foo]"
A map of the *creation id* to a Foo object. The Foo object MUST
contain an "id" property, which is the id (in the fromAccount) of
the record to be copied. When creating the copy, any other
properties included are used instead of the current value for that
property on the original.
o onSuccessDestroyOriginal: "Boolean" (default: false)
If true, an attempt will be made to destroy the original records
that were successfully copied: after emitting the "Foo/copy"
response, but before processing the next method, the server MUST
make a single call to "Foo/set" to destroy the original of each
successfully copied record; the output of this is added to the
responses as normal, to be returned to the client.
o destroyFromIfInState: "String|null"
This argument is passed on as the "ifInState" argument to the
implicit "Foo/set" call, if made at the end of this request to
destroy the originals that were successfully copied.
Each record copy is considered an atomic unit that may succeed or
fail individually.
The response has the following arguments:
o fromAccountId: "Id"
The id of the account records were copied from.
o accountId: "Id"
The id of the account records were copied to.
o oldState: "String|null"
The state string that would have been returned by "Foo/get" on the
account records that were copied to before making the requested
changes, or null if the server doesn't know what the previous
state string was.
o newState: "String"
The state string that will now be returned by "Foo/get" on the
account records were copied to.
o created: "Id[Foo]|null"
A map of the creation id to an object containing any properties of
the copied Foo object that are set by the server (such as the "id"
in most object types; note, the id is likely to be different to
the id of the object in the account it was copied from).
This argument is null if no Foo objects were successfully copied.
o notCreated: "Id[SetError]|null"
A map of the creation id to a SetError object for each record that
failed to be copied, or null if none.
The SetError may be any of the standard set errors returned for a
create or update. In addition, the following SetError is defined:
"alreadyExists": The server forbids duplicates, and the record
already exists in the target account. An "existingId" property of
type "Id" MUST be included on the SetError object with the id of the
existing record.
The following additional errors may be returned instead of the "Foo/
copy" response:
"fromAccountNotFound": The "fromAccountId" does not correspond to a
valid account.
"fromAccountNotSupportedByMethod": The "fromAccountId" given
corresponds to a valid account, but the account does not support this
data type.
"stateMismatch": An "ifInState" argument was supplied and it does not
match the current state, or an "ifFromInState" argument was supplied
and it does not match the current state in the from account.
5.5. /query
For data sets where the total amount of data is expected to be very
small, clients can just fetch the complete set of data and then do
any sorting/filtering locally. However, for large data sets (e.g.,
multi-gigabyte mailboxes), the client needs to be able to
search/sort/window the data type on the server.
A query on the set of Foos in an account is made by calling "Foo/
query". This takes a number of arguments to determine which records
to include, how they should be sorted, and which part of the result
should be returned (the full list may be *very* long). The result is
returned as a list of Foo ids.
A call to "Foo/query" takes the following arguments:
o accountId: "Id"
The id of the account to use.
o filter: "FilterOperator|FilterCondition|null"
Determines the set of Foos returned in the results. If null, all
objects in the account of this type are included in the results.
A *FilterOperator* object has the following properties:
* operator: "String"
This MUST be one of the following strings:
+ "AND": All of the conditions must match for the filter to
match.
+ "OR": At least one of the conditions must match for the
filter to match.
+ "NOT": None of the conditions must match for the filter to
match.
* conditions: "(FilterOperator|FilterCondition)[]"
The conditions to evaluate against each record.
A *FilterCondition* is an "object" whose allowed properties and
semantics depend on the data type and is defined in the /query
method specification for that type. It MUST NOT have an
"operator" property.
o sort: "Comparator[]|null"
Lists the names of properties to compare between two Foo records,
and how to compare them, to determine which comes first in the
sort. If two Foo records have an identical value for the first
comparator, the next comparator will be considered, and so on. If
all comparators are the same (this includes the case where an
empty array or null is given as the "sort" argument), the sort
order is server dependent, but it MUST be stable between calls to
"Foo/query". A *Comparator* has the following properties:
* property: "String"
The name of the property on the Foo objects to compare.
* isAscending: "Boolean" (optional; default: true)
If true, sort in ascending order. If false, reverse the
comparator's results to sort in descending order.
* collation: "String" (optional; default is server-dependent)
The identifier, as registered in the collation registry defined
in [RFC4790], for the algorithm to use when comparing the order
of strings. The algorithms the server supports are advertised
in the capabilities object returned with the Session object
(see Section 2).
If omitted, the default algorithm is server dependent, but:
1. It MUST be unicode-aware.
2. It MAY be selected based on an Accept-Language header in
the request (as defined in [RFC7231], Section 5.3.5) or
out-of-band information about the user's language/locale.
3. It SHOULD be case insensitive where such a concept makes
sense for a language/locale. Where the user's language is
unknown, it is RECOMMENDED to follow the advice in
Section 5.2.3 of [RFC8264].
The "i;unicode-casemap" collation [RFC5051] and the Unicode
Collation Algorithm (<http://www.unicode.org/reports/tr10/>)
are two examples that fulfil these criterion and provide
reasonable behaviour for a large number of languages.
When the property being compared is not a string, the
"collation" property is ignored, and the following comparison
rules apply based on the type. In ascending order:
+ "Boolean": false comes before true.
+ "Number": A lower number comes before a higher number.
+ "Date"/"UTCDate": The earlier date comes first.
The Comparator object may also have additional properties as
required for specific sort operations defined in a type's /query
method.
o position: "Int" (default: 0)
The zero-based index of the first id in the full list of results
to return.
If a negative value is given, it is an offset from the end of the
list. Specifically, the negative value MUST be added to the total
number of results given the filter, and if still negative, it's
clamped to "0". This is now the zero-based index of the first id
to return.
If the index is greater than or equal to the total number of
objects in the results list, then the "ids" array in the response
will be empty, but this is not an error.
o anchor: "Id|null"
A Foo id. If supplied, the "position" argument is ignored. The
index of this id in the results will be used in combination with
the "anchorOffset" argument to determine the index of the first
result to return (see below for more details).
o anchorOffset: "Int" (default: 0)
The index of the first result to return relative to the index of
the anchor, if an anchor is given. This MAY be negative. For
example, "-1" means the Foo immediately preceding the anchor is
the first result in the list returned (see below for more
details).
o limit: "UnsignedInt|null"
The maximum number of results to return. If null, no limit
presumed. The server MAY choose to enforce a maximum "limit"
argument. In this case, if a greater value is given (or if it is
null), the limit is clamped to the maximum; the new limit is
returned with the response so the client is aware. If a negative
value is given, the call MUST be rejected with an
"invalidArguments" error.
o calculateTotal: "Boolean" (default: false)
Does the client wish to know the total number of results in the
query? This may be slow and expensive for servers to calculate,
particularly with complex filters, so clients should take care to
only request the total when needed.
If an "anchor" argument is given, the anchor is looked for in the
results after filtering and sorting. If found, the "anchorOffset" is
then added to its index. If the resulting index is now negative, it
is clamped to 0. This index is now used exactly as though it were
supplied as the "position" argument. If the anchor is not found, the
call is rejected with an "anchorNotFound" error.
If an "anchor" is specified, any position argument supplied by the
client MUST be ignored. If no "anchor" is supplied, any
"anchorOffset" argument MUST be ignored.
A client can use "anchor" instead of "position" to find the index of
an id within a large set of results.
The response has the following arguments:
o accountId: "Id"
The id of the account used for the call.
o queryState: "String"
A string encoding the current state of the query on the server.
This string MUST change if the results of the query (i.e., the
matching ids and their sort order) have changed. The queryState
string MAY change if something has changed on the server, which
means the results may have changed but the server doesn't know for
sure.
The queryState string only represents the ordered list of ids that
match the particular query (including its sort/filter). There is
no requirement for it to change if a property on an object
matching the query changes but the query results are unaffected
(indeed, it is more efficient if the queryState string does not
change in this case). The queryState string only has meaning when
compared to future responses to a query with the same type/sort/
filter or when used with /queryChanges to fetch changes.
Should a client receive back a response with a different
queryState string to a previous call, it MUST either throw away
the currently cached query and fetch it again (note, this does not
require fetching the records again, just the list of ids) or call
"Foo/queryChanges" to get the difference.
o canCalculateChanges: "Boolean"
This is true if the server supports calling "Foo/queryChanges"
with these "filter"/"sort" parameters. Note, this does not
guarantee that the "Foo/queryChanges" call will succeed, as it may
only be possible for a limited time afterwards due to server
internal implementation details.
o position: "UnsignedInt"
The zero-based index of the first result in the "ids" array within
the complete list of query results.
o ids: "Id[]"
The list of ids for each Foo in the query results, starting at the
index given by the "position" argument of this response and
continuing until it hits the end of the results or reaches the
"limit" number of ids. If "position" is >= "total", this MUST be
the empty list.
o total: "UnsignedInt" (only if requested)
The total number of Foos in the results (given the "filter").
This argument MUST be omitted if the "calculateTotal" request
argument is not true.
o limit: "UnsignedInt" (if set by the server)
The limit enforced by the server on the maximum number of results
to return. This is only returned if the server set a limit or
used a different limit than that given in the request.
The following additional errors may be returned instead of the "Foo/
query" response:
"anchorNotFound": An anchor argument was supplied, but it cannot be
found in the results of the query.
"unsupportedSort": The "sort" is syntactically valid, but it includes
a property the server does not support sorting on or a collation
method it does not recognise.
"unsupportedFilter": The "filter" is syntactically valid, but the
server cannot process it. If the filter was the result of a user's
search input, the client SHOULD suggest that the user simplify their
search.
5.6. /queryChanges
The "Foo/queryChanges" method allows a client to efficiently update
the state of a cached query to match the new state on the server. It
takes the following arguments:
o accountId: "Id"
The id of the account to use.
o filter: "FilterOperator|FilterCondition|null"
The filter argument that was used with "Foo/query".
o sort: "Comparator[]|null"
The sort argument that was used with "Foo/query".
o sinceQueryState: "String"
The current state of the query in the client. This is the string
that was returned as the "queryState" argument in the "Foo/query"
response with the same sort/filter. The server will return the
changes made to the query since this state.
o maxChanges: "UnsignedInt|null"
The maximum number of changes to return in the response. See
error descriptions below for more details.
o upToId: "Id|null"
The last (highest-index) id the client currently has cached from
the query results. When there are a large number of results, in a
common case, the client may have only downloaded and cached a
small subset from the beginning of the results. If the sort and
filter are both only on immutable properties, this allows the
server to omit changes after this point in the results, which can
significantly increase efficiency. If they are not immutable,
this argument is ignored.
o calculateTotal: "Boolean" (default: false)
Does the client wish to know the total number of results now in
the query? This may be slow and expensive for servers to
calculate, particularly with complex filters, so clients should
take care to only request the total when needed.
The response has the following arguments:
o accountId: "Id"
The id of the account used for the call.
o oldQueryState: "String"
This is the "sinceQueryState" argument echoed back; that is, the
state from which the server is returning changes.
o newQueryState: "String"
This is the state the query will be in after applying the set of
changes to the old state.
o total: "UnsignedInt" (only if requested)
The total number of Foos in the results (given the "filter").
This argument MUST be omitted if the "calculateTotal" request
argument is not true.
o removed: "Id[]"
The "id" for every Foo that was in the query results in the old
state and that is not in the results in the new state.
If the server cannot calculate this exactly, the server MAY return
the ids of extra Foos in addition that may have been in the old
results but are not in the new results.
If the sort and filter are both only on immutable properties and
an "upToId" is supplied and exists in the results, any ids that
were removed but have a higher index than "upToId" SHOULD be
omitted.
If the "filter" or "sort" includes a mutable property, the server
MUST include all Foos in the current results for which this
property may have changed. The position of these may have moved
in the results, so they must be reinserted by the client to ensure
its query cache is correct.
o added: "AddedItem[]"
The id and index in the query results (in the new state) for every
Foo that has been added to the results since the old state AND
every Foo in the current results that was included in the
"removed" array (due to a filter or sort based upon a mutable
property).
If the sort and filter are both only on immutable properties and
an "upToId" is supplied and exists in the results, any ids that
were added but have a higher index than "upToId" SHOULD be
omitted.
The array MUST be sorted in order of index, with the lowest index
first.
An *AddedItem* object has the following properties:
* id: "Id"
* index: "UnsignedInt"
The result of this is that if the client has a cached sparse array of
Foo ids corresponding to the results in the old state, then:
fooIds = [ "id1", "id2", null, null, "id3", "id4", null, null, null ]
If it *splices out* all ids in the removed array that it has in its
cached results, then:
removed = [ "id2", "id31", ... ];
fooIds => [ "id1", null, null, "id3", "id4", null, null, null ]
and *splices in* (one by one in order, starting with the lowest
index) all of the ids in the added array:
added = [{ id: "id5", index: 0, ... }];
fooIds => [ "id5", "id1", null, null, "id3", "id4", null, null, null ]
and *truncates* or *extends* to the new total length, then the
results will now be in the new state.
Note: splicing in adds the item at the given index, incrementing the
index of all items previously at that or a higher index. Splicing
out is the inverse, removing the item and decrementing the index of
every item after it in the array.
The following additional errors may be returned instead of the "Foo/
queryChanges" response:
"tooManyChanges": There are more changes than the client's
"maxChanges" argument. Each item in the removed or added array is
considered to be one change. The client may retry with higher max
changes or invalidate its cache of the query results.
"cannotCalculateChanges": The server cannot calculate the changes
from the queryState string given by the client, usually due to the
client's state being too old. The client MUST invalidate its cache
of the query results.
5.7. Examples
Suppose we have a type *Todo* with the following properties:
o id: "Id" (immutable; server-set)
The id of the object.
o title: "String"
A brief summary of what is to be done.
o keywords: "String[Boolean]" (default: {})
A set of keywords that apply to the Todo. The set is represented
as an object, with the keys being the "keywords". The value for
each key in the object MUST be true. (This format allows you to
update an individual key using patch syntax rather than having to
update the whole set of keywords as one, which a "String[]"
representation would require.)
o neuralNetworkTimeEstimation: "Number" (server-set)
The title and keywords are fed into the server's state-of-the-art
neural network to get an estimation of how long this Todo will
take, in seconds.
o subTodoIds: "Id[]|null"
The ids of a list of other Todos to complete as part of this Todo.
Suppose also that all the standard methods are defined for this type
and the FilterCondition object supports a "hasKeyword" property to
match Todos with the given keyword.
A client might want to display the list of Todos with either a
"music" keyword or a "video" keyword, so it makes the following
method call:
[[ "Todo/query", {
"accountId": "x",
"filter": {
"operator": "OR",
"conditions": [
{ "hasKeyword": "music" },
{ "hasKeyword": "video" }
]
},
"sort": [{ "property": "title" }],
"position": 0,
"limit": 10
}, "0" ],
[ "Todo/get", {
"accountId": "x",
"#ids": {
"resultOf": "0",
"name": "Todo/query",
"path": "/ids"
}
}, "1" ]]
This would query the server for the set of Todos with a keyword of
either "music" or "video", sorted by title, and limited to the first
10 results. It fetches the full object for each of these Todos using
back-references to reference the result of the query. The response
might look something like:
[[ "Todo/query", {
"accountId": "x",
"queryState": "y13213",
"canCalculateChanges": true,
"position": 0,
"ids": [ "a", "b", "c", "d", "e", "f", "g", "h", "i", "j" ]
}, "0" ],
[ "Todo/get", {
"accountId": "x",
"state": "10324",
"list": [{
"id": "a",
"title": "Practise Piano",
"keywords": {
"music": true,
"beethoven": true,
"mozart": true,
"liszt": true,
"rachmaninov": true
},
"neuralNetworkTimeEstimation": 3600
}, {
"id": "b",
"title": "Watch Daft Punk music video",
"keywords": {
"music": true,
"video": true,
"trance": true
},
"neuralNetworkTimeEstimation": 18000
},
...
]
}, "1" ]]
Now, suppose the user adds a keyword "chopin" and removes the keyword
"mozart" from the "Practise Piano" task. The client may send the
whole object to the server, as this is a valid PatchObject:
[[ "Todo/set", {
"accountId": "x",
"ifInState": "10324",
"update": {
"a": {
"id": "a",
"title": "Practise Piano",
"keywords": {
"music": true,
"beethoven": true,
"chopin": true,
"liszt": true,
"rachmaninov": true
},
"neuralNetworkTimeEstimation": 360
}
}
}, "0" ]]
or it may send a minimal patch:
[[ "Todo/set", {
"accountId": "x",
"ifInState": "10324",
"update": {
"a": {
"keywords/chopin": true,
"keywords/mozart": null
}
}
}, "0" ]]
The effect is exactly the same on the server in either case, and
presuming the server is still in state "10324", it will probably
return success:
[[ "Todo/set", {
"accountId": "x",
"oldState": "10324",
"newState": "10329",
"updated": {
"a": {
"neuralNetworkTimeEstimation": 5400
}
}
}, "0" ]]
The server changed the "neuralNetworkTimeEstimation" property on the
object as part of this change; as this changed in a way *not*
explicitly requested by the PatchObject sent to the server, it is
returned with the "updated" confirmation.
Let us now add a sub-Todo to our new "Practise Piano" Todo. In this
example, we can see the use of a reference to a creation id to allow
us to set a foreign key reference to a record created in the same
request:
[[ "Todo/set", {
"accountId": "x",
"create": {
"k15": {
"title": "Warm up with scales"
}
},
"update": {
"a": {
"subTodoIds": [ "#k15" ]
}
}
}, "0" ]]
Now, suppose another user deleted the "Listen to Daft Punk" Todo.
The first user will receive a push notification (see Section 7) with
the changed state string for the "Todo" type. Since the new string
does not match its current state, it knows it needs to check for
updates. It may make a request like:
[[ "Todo/changes", {
"accountId": "x",
"sinceState": "10324",
"maxChanges": 50
}, "0" ],
[ "Todo/queryChanges", {
"accountId": "x",
"filter": {
"operator": "OR",
"conditions": [
{ "hasKeyword": "music" },
{ "hasKeyword": "video" }
]
},
"sort": [{ "property": "title" }],
"sinceQueryState": "y13213",
"maxChanges": 50
}, "1" ]]
and receive in response:
[[ "Todo/changes", {
"accountId": "x",
"oldState": "10324",
"newState": "871903",
"hasMoreChanges": false,
"created": [],
"updated": [],
"destroyed": ["b"]
}, "0" ],
[ "Todo/queryChanges", {
"accountId": "x",
"oldQueryState": "y13213",
"newQueryState": "y13218",
"removed": ["b"],
"added": null
}, "1" ]]
Suppose the user has access to another account "y", for example, a
team account shared between multiple users. To move an existing Todo
from account "x", the client would call:
[[ "Todo/copy", {
"fromAccountId": "x",
"accountId": "y",
"create": {
"k5122": {
"id": "a"
}
},
"onSuccessDestroyOriginal": true
}, "0" ]]
The server successfully copies the Todo to a new account (where it
receives a new id) and deletes the original. Due to the implicit
call to "Todo/set", there are two responses to the single method
call, both with the same method call id:
[[ "Todo/copy", {
"fromAccountId": "x",
"accountId": "y",
"created": {
"k5122": {
"id": "DAf97"
}
},
"oldState": "c1d64ecb038c",
"newState": "33844835152b"
}, "0" ],
[ "Todo/set", {
"accountId": "x",
"oldState": "871903",
"newState": "871909",
"destroyed": [ "a" ],
...
}, "0" ]]
5.8. Proxy Considerations
JMAP has been designed to allow an API endpoint to easily proxy
through to one or more JMAP servers. This may be useful for load
balancing, augmenting capabilities, or presenting a single endpoint
to accounts hosted on different JMAP servers (splitting the request
based on each method's "accountId" argument). The proxy need only
understand the general structure of a JMAP Request object; it does
not need to know anything specifically about the methods and
arguments it will pass through to other servers.
If splitting up the methods in a request to call them on different
backend servers, the proxy must do two things to ensure back-
references and creation-id references resolve the same as if the
entire request were processed on a single server:
1. It must pass a "createdIds" property with each subrequest. If
this is not given by the client, an empty object should be used
for the first subrequest. The "createdIds" property of each
subresponse should be passed on in the next subrequest.
2. It must resolve back-references to previous method results that
were processed on a different server. This is a relatively
simple syntactic substitution, described in Section 3.7.
When splitting a request based on accountId, proxy implementors do
need to be aware of "/copy" methods that copy between accounts. If
the accounts are on different servers, the proxy will have to
implement this functionality directly.
6. Binary Data
Binary data is referenced by a *blobId* in JMAP and uploaded/
downloaded separately to the core API. The blobId solely represents
the raw bytes of data, not any associated metadata such as a file
name or content type. Such metadata is stored alongside the blobId
in the object referencing it. The data represented by a blobId is
immutable.
Any blobId that exists within an account may be used when creating/
updating another object in that account. For example, an Email type
may have a blobId that represents the object in Internet Message
Format [RFC5322]. A client could create a new Email object with an
attachment and use this blobId, in effect attaching the old message
to the new one. Similarly, it could attach any existing attachment
of an old message without having to download and upload it again.
When the client uses a blobId in a create/update, the server MAY
assign a new blobId to refer to the same binary data within the new/
updated object. If it does so, it MUST return any properties that
contain a changed blobId in the created/updated response, so the
client gets the new ids.
A blob that is not referenced by a JMAP object (e.g., as a message
attachment) MAY be deleted by the server to free up resources.
Uploads (see below) are initially unreferenced blobs. To ensure
interoperability:
o The server SHOULD use a separate quota for unreferenced blobs to
the account's usual quota. In the case of shared accounts, this
quota SHOULD be separate per user.
o This quota SHOULD be at least the maximum total size that a single
object can reference on this server. For example, if supporting
JMAP Mail, this should be at least the maximum total attachments
size for a message.
o When an upload would take the user over quota, the server MUST
delete unreferenced blobs in date order, oldest first, until there
is room for the new blob.
o Except where quota restrictions force early deletion, an
unreferenced blob MUST NOT be deleted for at least 1 hour from the
time of upload; if reuploaded, the same blobId MAY be returned,
but this SHOULD reset the expiry time.
o A blob MUST NOT be deleted during the method call that removed the
last reference, so that a client can issue a create and a destroy
that both reference the blob within the same method call.
6.1. Uploading Binary Data
There is a single endpoint that handles all file uploads for an
account, regardless of what they are to be used for. The Session
object (see Section 2) has an "uploadUrl" property in URI Template
(level 1) format [RFC6570], which MUST contain a variable called
"accountId". The client may use this template in combination with an
"accountId" to get the URL of the file upload resource.
To upload a file, the client submits an authenticated POST request to
the file upload resource.
A successful request MUST return a single JSON object with the
following properties as the response:
o accountId: "Id"
The id of the account used for the call.
o blobId: "Id"
The id representing the binary data uploaded. The data for this
id is immutable. The id *only* refers to the binary data, not any
metadata.
o type: "String"
The media type of the file (as specified in [RFC6838],
Section 4.2) as set in the Content-Type header of the upload HTTP
request.
o size: "UnsignedInt"
The size of the file in octets.
If identical binary content to an existing blob in the account is
uploaded, the existing blobId MAY be returned.
Clients should use the blobId returned in a timely manner. Under
rare circumstances, the server may have deleted the blob before the
client uses it; the client should keep a reference to the local file
so it can upload it again in such a situation.
When an HTTP error response is returned to the client, the server
SHOULD return a JSON "problem details" object as the response body,
as per [RFC7807].
As access controls are often determined by the object holding the
reference to a blob, unreferenced blobs MUST only be accessible to
the uploader, even in shared accounts.
6.2. Downloading Binary Data
The Session object (see Section 2) has a "downloadUrl" property,
which is in URI Template (level 1) format [RFC6570]. The URL MUST
contain variables called "accountId", "blobId", "type", and "name".
To download a file, the client makes an authenticated GET request to
the download URL with the appropriate variables substituted in:
o "accountId": The id of the account to which the record with the
blobId belongs.
o "blobId": The blobId representing the data of the file to
download.
o "type": The type for the server to set in the "Content-Type"
header of the response; the blobId only represents the binary data
and does not have a content-type innately associated with it.
o "name": The name for the file; the server MUST return this as the
filename if it sets a "Content-Disposition" header.
As the data for a particular blobId is immutable, and thus the
response in the generated download URL is too, implementors are
recommended to set long cache times and use the "immutable" Cache-
Control extension [RFC8246] for successful responses, for example,
"Cache-Control: private, immutable, max-age=31536000".
When an HTTP error response is returned to the client, the server
SHOULD return a JSON "problem details" object as the response body,
as per [RFC7807].
6.3. Blob/copy
Binary data may be copied *between* two different accounts using the
"Blob/copy" method rather than having to download and then reupload
on the client.
The "Blob/copy" method takes the following arguments:
o fromAccountId: "Id"
The id of the account to copy blobs from.
o accountId: "Id"
The id of the account to copy blobs to.
o blobIds: "Id[]"
A list of ids of blobs to copy to the other account.
The response has the following arguments:
o fromAccountId: "Id"
The id of the account blobs were copied from.
o accountId: "Id"
The id of the account blobs were copied to.
o copied: "Id[Id]|null"
A map of the blobId in the fromAccount to the id for the blob in
the account it was copied to, or null if none were successfully
copied.
o notCopied: "Id[SetError]|null"
A map of blobId to a SetError object for each blob that failed to
be copied, or null if none.
The SetError may be any of the standard set errors that may be
returned for a create, as defined in Section 5.3. In addition, the
"notFound" SetError error may be returned if the blobId to be copied
cannot be found.
The following additional method-level error may be returned instead
of the "Blob/copy" response:
"fromAccountNotFound": The "fromAccountId" included with the request
does not correspond to a valid account.
7. Push
Push notifications allow clients to efficiently update (almost)
instantly to stay in sync with data changes on the server. The
general model for push is simple and sends minimal data over the push
channel: just enough for the client to know whether it needs to
resync. The format allows multiple changes to be coalesced into a
single push update and the frequency of pushes to be rate limited by
the server. It doesn't matter if some push events are dropped before
they reach the client; the next time it gets/sets any records of a
changed type, it will discover the data has changed and still sync
all changes.
There are two different mechanisms by which a client can receive push
notifications, to allow for the different environments in which a
client may exist. An event source resource (see Section 7.3) allows
clients that can hold transport connections open to receive push
notifications directly from the JMAP server. This is simple and
avoids third parties, but it is often not feasible on constrained
platforms such as mobile devices. Alternatively, clients can make
use of any push service supported by their environment. A URL for
the push service is registered with the JMAP server (see
Section 7.2); the server then POSTs each notification to that URL.
The push service is then responsible for routing these to the client.
7.1. The StateChange Object
When something changes on the server, the server pushes a StateChange
object to the client. A *StateChange* object has the following
properties:
o @type: "String"
This MUST be the string "StateChange".
o changed: "Id[TypeState]"
A map of an "account id" to an object encoding the state of data
types that have changed for that account since the last
StateChange object was pushed, for each of the accounts to which
the user has access and for which something has changed.
A *TypeState* object is a map. The keys are the type name "Foo"
(e.g., "Mailbox" or "Email"), and the value is the "state"
property that would currently be returned by a call to "Foo/get".
The client can compare the new state strings with its current
values to see whether it has the current data for these types. If
not, the changes can then be efficiently fetched in a single
standard API request (using the /changes type methods).
7.1.1. Example
In this example, the server has amalgamated a few changes together
across two different accounts the user has access to, before pushing
the following StateChange object to the client:
{
"@type": "StateChange",
"changed": {
"a3123": {
"Email": "d35ecb040aab",
"EmailDelivery": "428d565f2440",
"CalendarEvent": "87accfac587a"
},
"a43461d": {
"Mailbox": "0af7a512ce70",
"CalendarEvent": "7a4297cecd76"
}
}
}
The client can compare the state strings with its current state for
the Email, CalendarEvent, etc., object types in the appropriate
accounts to see if it needs to fetch changes.
If the client is itself making changes, it may receive a StateChange
object while the /set API call is in flight. It can wait until the
call completes and then compare if the new state string after the
/set is the same as was pushed in the StateChange object; if so, and
the old state of the /set response matches the client's previous
state, it does not need to waste a request asking for changes it
already knows.
7.2. PushSubscription
Clients may create a PushSubscription to register a URL with the JMAP
server. The JMAP server will then make an HTTP POST request to this
URL for each push notification it wishes to send to the client.
As a push subscription causes the JMAP server to make a number of
requests to a previously unknown endpoint, it can be used as a vector
for launching a denial-of-service attack. To prevent this, when a
subscription is created, the JMAP server immediately sends a
PushVerification object to that URL (see Section 7.2.2). The JMAP
server MUST NOT make any further requests to the URL until the client
receives the push and updates the subscription with the correct
verification code.
A *PushSubscription* object has the following properties:
o id: "Id" (immutable; server-set)
The id of the push subscription.
o deviceClientId: "String" (immutable)
An id that uniquely identifies the client + device it is running
on. The purpose of this is to allow clients to identify which
PushSubscription objects they created even if they lose their
local state, so they can revoke or update them. This string MUST
be different on different devices and be different from apps from
other vendors. It SHOULD be easy to regenerate and not depend on
persisted state. It is RECOMMENDED to use a secure hash of a
string that contains:
1. A unique identifier associated with the device where the JMAP
client is running, normally supplied by the device's operating
system.
2. A custom vendor/app id, including a domain controlled by the
vendor of the JMAP client.
To protect the privacy of the user, the deviceClientId id MUST NOT
contain an unobfuscated device id.
o url: "String" (immutable)
An absolute URL where the JMAP server will POST the data for the
push message. This MUST begin with "https://".
o keys: "Object|null" (immutable)
Client-generated encryption keys. If supplied, the server MUST
use them as specified in [RFC8291] to encrypt all data sent to the
push subscription. The object MUST have the following properties:
* p256dh: "String"
The P-256 Elliptic Curve Diffie-Hellman (ECDH) public key as
described in [RFC8291], encoded in URL-safe base64
representation as defined in [RFC4648].
* auth: "String"
The authentication secret as described in [RFC8291], encoded in
URL-safe base64 representation as defined in [RFC4648].
o verificationCode: "String|null"
This MUST be null (or omitted) when the subscription is created.
The JMAP server then generates a verification code and sends it in
a push message, and the client updates the PushSubscription object
with the code; see Section 7.2.2 for details.
o expires: "UTCDate|null"
The time this push subscription expires. If specified, the JMAP
server MUST NOT make further requests to this resource after this
time. It MAY automatically destroy the push subscription at or
after this time.
The server MAY choose to set an expiry if none is given by the
client or modify the expiry time given by the client to a shorter
duration.
o types: "String[]|null"
A list of types the client is interested in (using the same names
as the keys in the TypeState object defined in the previous
section). A StateChange notification will only be sent if the
data for one of these types changes. Other types are omitted from
the TypeState object. If null, changes will be pushed for all
types.
The POST request MUST have a content type of "application/json" and
contain the UTF-8 JSON-encoded object as the body. The request MUST
have a "TTL" header and MAY have "Urgency" and/or "Topic" headers, as
specified in Section 5 of [RFC8030]. The JMAP server is expected to
understand and handle HTTP status responses in a reasonable manner.
A "429" (Too Many Requests) response MUST cause the JMAP server to
reduce the frequency of pushes; the JMAP push structure allows
multiple changes to be coalesced into a single minimal StateChange
object. See the security considerations in Section 8.6 for a
discussion of the risks in connecting to unknown servers.
The JMAP server acts as an application server as defined in
[RFC8030]. A client MAY use the rest of [RFC8030] in combination
with its own push service to form a complete end-to-end solution, or
it MAY rely on alternative mechanisms to ensure the delivery of the
pushed data after it leaves the JMAP server.
The push subscription is tied to the credentials used to authenticate
the API request that created it. Should these credentials expire or
be revoked, the push subscription MUST be destroyed by the JMAP
server. Only subscriptions created by these credentials are returned
when the client fetches existing subscriptions.
When these credentials have their own expiry (i.e., it is a session
with a timeout), the server SHOULD NOT set or bound the expiry time
for the push subscription given by the client but MUST expire it when
the session expires.
When these credentials are not time bounded (e.g., Basic
authentication [RFC7617]), the server SHOULD set an expiry time for
the push subscription if none is given and limit the expiry time if
set too far in the future. This maximum expiry time MUST be at least
48 hours in the future and SHOULD be at least 7 days in the future.
An app running on a mobile device may only be able to refresh the
push subscription lifetime when it is in the foreground, so this
gives a reasonable time frame to allow this to happen.
In the case of separate access and refresh credentials, as in Oauth
2.0 [RFC6749], the server SHOULD tie the push subscription to the
validity of the refresh token rather than the access token and behave
according to whether this is time-limited or not.
When a push subscription is destroyed, the server MUST securely erase
the URL and encryption keys from memory and storage as soon as
possible.
7.2.1. PushSubscription/get
Standard /get method as described in Section 5.1, except it does
*not* take or return an "accountId" argument, as push subscriptions
are not tied to specific accounts. It also does *not* return a
"state" argument. The "ids" argument may be null to fetch all at
once.
The server MUST only return push subscriptions that were created
using the same authentication credentials as for this
"PushSubscription/get" request.
As the "url" and "keys" properties may contain data that is private
to a particular device, the values for these properties MUST NOT be
returned. If the "properties" argument is null or omitted, the
server MUST default to all properties excluding these two. If one of
them is explicitly requested, the method call MUST be rejected with a
"forbidden" error.
7.2.2. PushSubscription/set
Standard /set method as described in Section 5.3, except it does
*not* take or return an "accountId" argument, as push subscriptions
are not tied to specific accounts. It also does *not* take an
"ifInState" argument or return "oldState" or "newState" arguments.
The "url" and "keys" properties are immutable; if the client wishes
to change these, it must destroy the current push subscription and
create a new one.
When a PushSubscription is created, the server MUST immediately push
a *PushVerification* object to the URL. It has the following
properties:
o @type: "String"
This MUST be the string "PushVerification".
o pushSubscriptionId: "String"
The id of the push subscription that was created.
o verificationCode: "String"
The verification code to add to the push subscription. This MUST
contain sufficient entropy to avoid the client being able to guess
the code via brute force.
The client MUST update the push subscription with the correct
verification code before the server makes any further requests to the
subscription's URL. Attempts to update the subscription with an
invalid verification code MUST be rejected by the server with an
"invalidProperties" SetError.
The client may update the "expires" property to extend (or, less
commonly, shorten) the lifetime of a push subscription. The server
MAY modify the proposed new expiry time to enforce server-defined
limits. Extending the lifetime does not require the subscription to
be verified again.
Clients SHOULD NOT update or destroy a push subscription that they
did not create (i.e., has a "deviceClientId" that they do not
recognise).
7.2.3. Example
At "2018-07-06T02:14:29Z", a client with deviceClientId "a889-ffea-
910" fetches the set of push subscriptions currently on the server,
making an API request with:
[[ "PushSubscription/get", {
"ids": null
}, "0" ]]
Which returns:
[[ "PushSubscription/get", {
"list": [{
"id": "e50b2c1d-9553-41a3-b0a7-a7d26b599ee1",
"deviceClientId": "b37ff8001ca0",
"verificationCode": "b210ef734fe5f439c1ca386421359f7b",
"expires": "2018-07-31T00:13:21Z",
"types": [ "Todo" ]
}, {
"id": "f2d0aab5-e976-4e8b-ad4b-b380a5b987e4",
"deviceClientId": "X8980fc",
"verificationCode": "f3d4618a9ae15c8b7f5582533786d531",
"expires": "2018-07-12T05:55:00Z",
"types": [ "Mailbox", "Email", "EmailDelivery" ]
}],
"notFound": []
}, "0" ]]
Since neither of the returned push subscription objects have the
client's deviceClientId, it knows it does not have a current push
subscription active on the server. So it creates one, sending this
request:
[[ "PushSubscription/set", {
"create": {
"4f29": {
"deviceClientId": "a889-ffea-910",
"url": "https://example.com/push/?device=X8980fc&client=12c6d086",
"types": null
}
}
}, "0" ]]
The server creates the push subscription but limits the expiry time
to 7 days in the future, returning this response:
[[ "PushSubscription/set", {
"created": {
"4f29": {
"id": "P43dcfa4-1dd4-41ef-9156-2c89b3b19c60",
"keys": null,
"expires": "2018-07-13T02:14:29Z"
}
}
}, "0" ]]
The server also immediately makes a POST request to
"https://example.com/push/?device=X8980fc&client=12c6d086" with the
data:
{
"@type": "PushVerification",
"pushSubscriptionId": "P43dcfa4-1dd4-41ef-9156-2c89b3b19c60",
"verificationCode": "da1f097b11ca17f06424e30bf02bfa67"
}
The client receives this and updates the subscription with the
verification code (note there is a potential race condition here; the
client MUST be able to handle receiving the push while the request
creating the subscription is still in progress):
[[ "PushSubscription/set", {
"update": {
"P43dcfa4-1dd4-41ef-9156-2c89b3b19c60": {
"verificationCode": "da1f097b11ca17f06424e30bf02bfa67"
}
}
}, "0" ]]
The server confirms the update was successful and will now make
requests to the registered URL when the state changes.
Two days later, the client updates the subscription to extend its
lifetime, sending this request:
[[ "PushSubscription/set", {
"update": {
"P43dcfa4-1dd4-41ef-9156-2c89b3b19c60": {
"expires": "2018-08-13T00:00:00Z"
}
}
}, "0" ]]
The server extends the expiry time, but only again to its maximum
limit of 7 days in the future, returning this response:
[[ "PushSubscription/set", {
"updated": {
"P43dcfa4-1dd4-41ef-9156-2c89b3b19c60": {
"expires": "2018-07-15T02:22:50Z"
}
}
}, "0" ]]
7.3. Event Source
Clients that can hold transport connections open can connect directly
to the JMAP server to receive push notifications via a "text/event-
stream" resource, as described in [EventSource]. This is a long
running HTTP request, where the server can push data to the client by
appending data without ending the response.
When a change occurs in the data on the server, it pushes an event
called "state" to any connected clients, with the StateChange object
as the data.
The server SHOULD also send a new event id that encodes the entire
server state visible to the user immediately after sending a "state"
event. When a new connection is made to the event-source endpoint, a
client following the server-sent events specification will send a
Last-Event-ID HTTP header field with the last id it saw, which the
server can use to work out whether the client has missed some
changes. If so, it SHOULD send these changes immediately on
connection.
The Session object (see Section 2) has an "eventSourceUrl" property,
which is in URI Template (level 1) format [RFC6570]. The URL MUST
contain variables called "types", "closeafter", and "ping".
To connect to the resource, the client makes an authenticated GET
request to the event-source URL with the appropriate variables
substituted in:
o "types": This MUST be either:
* A comma-separated list of type names, e.g.,
"Email,CalendarEvent". The server MUST only push changes for
the types in this list.
* The single character: "*". Changes to all types are pushed.
o "closeafter": This MUST be one of the following values:
* "state": The server MUST end the HTTP response after pushing a
state event. This can be used by clients in environments where
buffering proxies prevent the pushed data from arriving
immediately, or indeed at all, when operating in the usual
mode.
* "no": The connection is persisted by the server as a standard
event-source resource.
o "ping": A positive integer value representing a length of time in
seconds, e.g., "300". If non-zero, the server MUST send an event
called "ping" whenever this time elapses since the previous event
was sent. This MUST NOT set a new event id. If the value is "0",
the server MUST NOT send ping events.
The server MAY modify a requested ping interval to be subject to a
minimum and/or maximum value. For interoperability, servers MUST
NOT have a minimum allowed value higher than 30 or a maximum
allowed value less than 300.
The data for the ping event MUST be a JSON object containing an
"interval" property, the value (type "UnsignedInt") being the
interval in seconds the server is using to send pings (this may be
different to the requested value if the server clamped it to be
within a min/max value).
Clients can monitor for the ping event to help determine when the
closeafter mode may be required.
A client MAY hold open multiple connections to the event-source
resource, although it SHOULD try to use a single connection for
efficiency.
8. Security Considerations
8.1. Transport Confidentiality
To ensure the confidentiality and integrity of data sent and received
via JMAP, all requests MUST use TLS 1.2 [RFC5246] [RFC8446] or later,
following the recommendations in [RFC7525]. Servers SHOULD support
TLS 1.3 [RFC8446] or later.
Clients MUST validate TLS certificate chains to protect against
man-in-the-middle attacks [RFC5280].
8.2. Authentication Scheme
A number of HTTP authentication schemes have been standardised (see
<https://www.iana.org/assignments/http-authschemes/>). Servers
should take care to assess the security characteristics of different
schemes in relation to their needs when deciding what to implement.
Use of the Basic authentication scheme is NOT RECOMMENDED. Services
that choose to use it are strongly recommended to require generation
of a unique "app password" via some external mechanism for each
client they wish to connect. This allows connections from different
devices to be differentiated by the server and access to be
individually revoked.
8.3. Service Autodiscovery
Unless secured by something like DNSSEC, autodiscovery of server
details using SRV DNS records is vulnerable to a DNS poisoning
attack, which can lead to the client talking to an attacker's server
instead of the real JMAP server. The attacker may then intercept
requests to execute man-in-the-middle attacks and, depending on the
authentication scheme, steal credentials to generate its own
requests.
Clients that do not support SRV lookups are likely to try just using
the "/.well-known/jmap" path directly against the domain of the
username over HTTPS. Servers SHOULD ensure this path resolves or
redirects to the correct JMAP Session resource to allow this to work.
If this is not feasible, servers MUST ensure this path cannot be
controlled by an attacker, as again it may be used to steal
credentials.
8.4. JSON Parsing
The Security Considerations of [RFC8259] apply to the use of JSON as
the data interchange format.
As for any serialization format, parsers need to thoroughly check the
syntax of the supplied data. JSON uses opening and closing tags for
several types and structures, and it is possible that the end of the
supplied data will be reached when scanning for a matching closing
tag; this is an error condition, and implementations need to stop
scanning at the end of the supplied data.
JSON also uses a string encoding with some escape sequences to encode
special characters within a string. Care is needed when processing
these escape sequences to ensure that they are fully formed before
the special processing is triggered, with special care taken when the
escape sequences appear adjacent to other (non-escaped) special
characters or adjacent to the end of data (as in the previous
paragraph).
If parsing JSON into a non-textual structured data format,
implementations may need to allocate storage to hold JSON string
elements. Since JSON does not use explicit string lengths, the risk
of denial of service due to resource exhaustion is small, but
implementations may still wish to place limits on the size of
allocations they are willing to make in any given context, to avoid
untrusted data causing excessive memory allocation.
8.5. Denial of Service
A small request may result in a very large response and require
considerable work on the server if resource limits are not enforced.
JMAP provides mechanisms for advertising and enforcing a wide variety
of limits for mitigating this threat, including limits on the number
of objects fetched in a single method call, number of methods in a
single request, number of concurrent requests, etc.
JMAP servers MUST implement sensible limits to mitigate against
resource exhaustion attacks.
8.6. Connection to Unknown Push Server
When a push subscription is registered, the application server will
make POST requests to the given URL. There are a number of security
considerations that MUST be considered when implementing this.
The server MUST ensure the URL is externally resolvable to avoid
server-side request forgery, where the server makes a request to a
resource on its internal network.
A malicious client may use the push subscription to attempt to flood
a third party server with requests, creating a denial-of-service
attack and masking the attacker's true identity. There is no
guarantee that the URL given to the JMAP server is actually a valid
push server. Upon creation of a push subscription, the JMAP server
sends a PushVerification object to the URL and MUST NOT send any
further requests until the client verifies it has received the
initial push. The verification code MUST contain sufficient entropy
to prevent the client from being able to verify the subscription via
brute force.
The verification code does not guarantee the URL is a valid push
server, only that the client is able to access the data submitted to
it. While the verification step significantly reduces the set of
potential targets, there is still a risk that the server is unrelated
to the client and being targeted for a denial-of-service attack.
The server MUST limit the number of push subscriptions any one user
may have to ensure the user cannot cause the server to send a large
number of push notifications at once, which could again be used as
part of a denial-of-service attack. The rate of creation MUST also
be limited to minimise the ability to abuse the verification request
as an attack vector.
8.7. Push Encryption
When data changes, a small object is pushed with the new state
strings for the types that have changed. While the data here is
minimal, a passive man-in-the-middle attacker may be able to gain
useful information. To ensure confidentiality and integrity, if the
push is sent via a third party outside of the control of the client
and JMAP server, the client MUST specify encryption keys when
establishing the PushSubscription and ignore any push notification
received that is not encrypted with those keys.
The privacy and security considerations of [RFC8030] and [RFC8291]
also apply to the use of the PushSubscription mechanism.
As there is no crypto algorithm agility in Web Push Encryption
[RFC8291], a new specification will be needed to provide this if new
algorithms are required in the future.
8.8. Traffic Analysis
While the data is encrypted, a passive observer with the ability to
monitor network traffic may be able to glean information from the
timing of API requests and push notifications. For example, suppose
an email or calendar invitation is sent from User A (hosted on Server
X) to User B (hosted on Server Y). If Server X hosts data for many
users, a passive observer can see that the two servers connected but
does not know who the data was for. However, if a push notification
is immediately sent to User B and the attacker can observe this as
well, they may reasonably conclude that someone on Server X is
connecting to User B.
9. IANA Considerations
9.1. Assignment of jmap Service Name
IANA has assigned the 'jmap' service name in the "Service Name and
Transport Protocol Port Number Registry" [RFC6335].
Service Name: jmap
Transport Protocol(s): tcp
Assignee: IESG
Contact: IETF Chair
Description: JSON Meta Application Protocol
Reference: RFC 8620
Assignment Notes: This service name was previously assigned under the
name "JSON Mail Access Protocol". This has been de-assigned and
re-assigned with the approval of the previous assignee.
9.2. Registration of Well-Known URI Suffix for JMAP
IANA has registered the following suffix in the "Well-Known URIs"
registry for JMAP, as described in [RFC8615]:
URI Suffix: jmap
Change Controller: IETF
Specification Document: RFC 8620, Section 2.2.
9.3. Registration of the jmap URN Sub-namespace
IANA has registered the following URN sub-namespace in the "IETF URN
Sub-namespace for Registered Protocol Parameter Identifiers" registry
within the "Uniform Resource Name (URN) Namespace for IETF Use"
registry as described in [RFC3553].
Registered Parameter Identifier: jmap
Reference: RFC 8620, Section 9.4
IANA Registry Reference: http://www.iana.org/assignments/jmap
9.4. Creation of "JMAP Capabilities" Registry
IANA has created the "JMAP Capabilities" registry as described in
Section 2. JMAP capabilities are advertised in the "capabilities"
property of the JMAP Session resource. They are used to extend the
functionality of a JMAP server. A capability is referenced by a URI.
The JMAP capability URI can be a URN starting with
"urn:ietf:params:jmap:" plus a unique suffix that is the index value
in the jmap URN sub-namespace. Registration of a JMAP capability
with another form of URI has no impact on the jmap URN sub-namespace.
This registry follows the expert review process unless the "intended
use" field is "common" or "placeholder", in which case registration
follows the specification required process.
A JMAP capability registration can have an intended use of "common",
"placeholder", "limited", or "obsolete". IANA will list common-use
registrations prominently and separately from those with other
intended use values.
The JMAP capability registration procedure is not a formal standards
process but rather an administrative procedure intended to allow
community comment and sanity checking without excessive time delay.
A "placeholder" registration reserves part of the jmap URN namespace
for another purpose but is typically not included in the
"capabilities" property of the JMAP Session resource.
9.4.1. Preliminary Community Review
Notice of a potential JMAP common-use registration SHOULD be sent to
the JMAP mailing list <jmap@ietf.org> for review. This mailing list
is appropriate to solicit community feedback on a proposed JMAP
capability. Registrations that are not intended for common use MAY
be sent to the list for review as well; doing so is entirely
OPTIONAL, but is encouraged.
The intent of the public posting to this list is to solicit comments
and feedback on the choice of the capability name, the unambiguity of
the specification document, and a review of any interoperability or
security considerations. The submitter may submit a revised
registration proposal or abandon the registration completely at any
time.
9.4.2. Submit Request to IANA
Registration requests can be sent to <iana@iana.org>.
9.4.3. Designated Expert Review
For a limited-use registration, the primary concern of the designated
expert (DE) is preventing name collisions and encouraging the
submitter to document security and privacy considerations; a
published specification is not required. For a common-use
registration, the DE is expected to confirm that suitable
documentation, as described in Section 4.6 of [RFC8126], is
available. The DE should also verify that the capability does not
conflict with work that is active or already published within the
IETF.
Before a period of 30 days has passed, the DE will either approve or
deny the registration request and publish a notice of the decision to
the JMAP WG mailing list or its successor, as well as inform IANA. A
denial notice must be justified by an explanation, and, in the cases
where it is possible, concrete suggestions on how the request can be
modified so as to become acceptable should be provided.
If the DE does not respond within 30 days, the registrant may request
the IESG take action to process the request in a timely manner.
9.4.4. Change Procedures
Once a JMAP capability has been published by the IANA, the change
controller may request a change to its definition. The same
procedure that would be appropriate for the original registration
request is used to process a change request.
JMAP capability registrations may not be deleted; capabilities that
are no longer believed appropriate for use can be declared obsolete
by a change to their "intended use" field; such capabilities will be
clearly marked in the lists published by the IANA.
Significant changes to a capability's definition should be requested
only when there are serious omissions or errors in the published
specification. When review is required, a change request may be
denied if it renders entities that were valid under the previous
definition invalid under the new definition.
The owner of a JMAP capability may pass responsibility to another
person or agency by informing the IANA; this can be done without
discussion or review.
The IESG may reassign responsibility for a JMAP capability. The most
common case of this will be to enable changes to be made to
capabilities where the author of the registration has died, moved out
of contact, or is otherwise unable to make changes that are important
to the community.
9.4.5. JMAP Capabilities Registry Template
Capability name: (see capability property in Section 2)
Specification document:
Intended use: (one of common, limited, placeholder, or obsolete)
Change controller: ("IETF" for Standards Track / BCP RFCs)
Security and privacy considerations:
9.4.6. Initial Registration for JMAP Core
Capability Name: "urn:ietf:params:jmap:core"
Specification document: RFC 8620, Section 2
Intended use: common
Change Controller: IETF
Security and privacy considerations: RFC 8620, Section 8.
9.4.7. Registration for JMAP Error Placeholder in JMAP Capabilities
Registry
Capability Name: "urn:ietf:params:jmap:error:"
Specification document: RFC 8620, Section 9.5
Intended use: placeholder
Change Controller: IETF
Security and privacy considerations: RFC 8620, Section 8.
9.5. Creation of "JMAP Error Codes" Registry
IANA has created the "JMAP Error Codes" registry. JMAP error codes
appear in the "type" member of a JSON problem details object (as
described in Section 3.6.1), the "type" member in a JMAP error object
(as described in Section 3.6.2), or the "type" member of a JMAP
method-specific error object (such as SetError in Section 5.3). When
used in a problem details object, the prefix
"urn:ietf:params:jmap:error:" is always included; when used in JMAP
objects, the prefix is always omitted.
This registry follows the expert review process. Preliminary
community review for this registry follows the same procedures as the
"JMAP Capabilities" registry, but it is optional. The change
procedures for this registry are the same as the change procedures
for the "JMAP Capabilities" registry.
9.5.1. Expert Review
The designated expert should review the following aspects of the
registration:
1. Verify the error code does not conflict with existing names.
2. Verify the error code follows the syntax limitations (does not
require URI encoding).
3. Encourage the submitter to follow the naming convention of
previously registered errors.
4. Encourage the submitter to describe client behaviours that are
recommended in response to the error code. These may distinguish
the error code from other error codes.
5. Encourage the submitter to describe when the server should issue
the error as opposed to some other error code.
6. Encourage the submitter to note any security considerations
associated with the error, if any (e.g., an error code that might
disclose existence of data the authenticated user does not have
permission to know about).
Steps 3-6 are meant to promote a higher-quality registry. However,
the expert is encouraged to approve any registration that would not
actively harm JMAP interoperability to make this a relatively
lightweight process.
9.5.2. JMAP Error Codes Registry Template
JMAP Error Code:
Intended use: (one of "common", "limited", "obsolete")
Change Controller: ("IETF" for Standards Track / BCP RFCs)
Reference: (Optional. Only required if defined in an RFC.)
Description:
9.5.3. Initial Contents for the JMAP Error Codes Registry
o JMAP Error Code: accountNotFound
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 3.6.2
Description: The accountId does not correspond to a valid account.
o JMAP Error Code: accountNotSupportedByMethod
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 3.6.2
Description: The accountId given corresponds to a valid account,
but the account does not support this method or data type.
o JMAP Error Code: accountReadOnly
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 3.6.2
Description: This method modifies state, but the account is read-
only (as returned on the corresponding Account object in the JMAP
Session resource).
o JMAP Error Code: anchorNotFound
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.5
Description: An anchor argument was supplied, but it cannot be
found in the results of the query.
o JMAP Error Code: alreadyExists
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.4
Description: The server forbids duplicates, and the record already
exists in the target account. An existingId property of type Id
MUST be included on the SetError object with the id of the
existing record.
o JMAP Error Code: cannotCalculateChanges
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Sections 5.2 and 5.6
Description: The server cannot calculate the changes from the
state string given by the client.
o JMAP Error Code: forbidden
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Sections 3.6.2, 5.3, and 7.2.1
Description: The action would violate an ACL or other permissions
policy.
o JMAP Error Code: fromAccountNotFound
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Sections 5.4 and 6.3
Description: The fromAccountId does not correspond to a valid
account.
o JMAP Error Code: fromAccountNotSupportedByMethod
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.4
Description: The fromAccountId given corresponds to a valid
account, but the account does not support this data type.
o JMAP Error Code: invalidArguments
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 3.6.2
Description: One of the arguments is of the wrong type or
otherwise invalid, or a required argument is missing.
o JMAP Error Code: invalidPatch
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.3
Description: The PatchObject given to update the record was not a
valid patch.
o JMAP Error Code: invalidProperties
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.3
Description: The record given is invalid.
o JMAP Error Code: notFound
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.3
Description: The id given cannot be found.
o JMAP Error Code: notJSON
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 3.6.1
Description: The content type of the request was not application/
json, or the request did not parse as I-JSON.
o JMAP Error Code: notRequest
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 3.6.1
Description: The request parsed as JSON but did not match the type
signature of the Request object.
o JMAP Error Code: overQuota
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.3
Description: The create would exceed a server-defined limit on the
number or total size of objects of this type.
o JMAP Error Code: rateLimit
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.3
Description: Too many objects of this type have been created
recently, and a server-defined rate limit has been reached. It
may work if tried again later.
o JMAP Error Code: requestTooLarge
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Sections 5.1 and 5.3
Description: The total number of actions exceeds the maximum
number the server is willing to process in a single method call.
o JMAP Error Code: invalidResultReference
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 3.6.2
Description: The method used a result reference for one of its
arguments, but this failed to resolve.
o JMAP Error Code: serverFail
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 3.6.2
Description: An unexpected or unknown error occurred during the
processing of the call. The method call made no changes to the
server's state.
o JMAP Error Code: serverPartialFail
Intended Use: Limited
Change Controller: IETF
Reference: RFC 8620, Section 3.6.2
Description: Some, but not all, expected changes described by the
method occurred. The client MUST resynchronise impacted data to
determine the server state. Use of this error is strongly
discouraged.
o JMAP Error Code: serverUnavailable
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 3.6.2
Description: Some internal server resource was temporarily
unavailable. Attempting the same operation later (perhaps after a
backoff with a random factor) may succeed.
o JMAP Error Code: singleton
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.3
Description: This is a singleton type, so you cannot create
another one or destroy the existing one.
o JMAP Error Code: stateMismatch
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.3
Description: An ifInState argument was supplied, and it does not
match the current state.
o JMAP Error Code: tooLarge
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.3
Description: The action would result in an object that exceeds a
server-defined limit for the maximum size of a single object of
this type.
o JMAP Error Code: tooManyChanges
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.6
Description: There are more changes than the client's maxChanges
argument.
o JMAP Error Code: unknownCapability
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 3.6.1
Description: The client included a capability in the "using"
property of the request that the server does not support.
o JMAP Error Code: unknownMethod
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 3.6.2
Description: The server does not recognise this method name.
o JMAP Error Code: unsupportedFilter
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.5
Description: The filter is syntactically valid, but the server
cannot process it.
o JMAP Error Code: unsupportedSort
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.5
Description: The sort is syntactically valid but includes a
property the server does not support sorting on or a collation
method it does not recognise.
o JMAP Error Code: willDestroy
Intended Use: Common
Change Controller: IETF
Reference: RFC 8620, Section 5.3
Description: The client requested an object be both updated and
destroyed in the same /set request, and the server has decided to
therefore ignore the update.
10. References
10.1. Normative References
[EventSource]
Hickson, I., "Server-Sent Events", World Wide Web
Consortium Recommendation REC-eventsource-20150203,
February 2015, <https://www.w3.org/TR/eventsource/>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
specifying the location of services (DNS SRV)", RFC 2782,
DOI 10.17487/RFC2782, February 2000,
<https://www.rfc-editor.org/info/rfc2782>.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000,
<https://www.rfc-editor.org/info/rfc2818>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<https://www.rfc-editor.org/info/rfc3339>.
[RFC3553] Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An
IETF URN Sub-namespace for Registered Protocol
Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553, June
2003, <https://www.rfc-editor.org/info/rfc3553>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <https://www.rfc-editor.org/info/rfc3629>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/info/rfc4648>.
[RFC4790] Newman, C., Duerst, M., and A. Gulbrandsen, "Internet
Application Protocol Collation Registry", RFC 4790,
DOI 10.17487/RFC4790, March 2007,
<https://www.rfc-editor.org/info/rfc4790>.
[RFC5051] Crispin, M., "i;unicode-casemap - Simple Unicode Collation
Algorithm", RFC 5051, DOI 10.17487/RFC5051, October 2007,
<https://www.rfc-editor.org/info/rfc5051>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<https://www.rfc-editor.org/info/rfc5280>.
[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
DOI 10.17487/RFC5322, October 2008,
<https://www.rfc-editor.org/info/rfc5322>.
[RFC6186] Daboo, C., "Use of SRV Records for Locating Email
Submission/Access Services", RFC 6186,
DOI 10.17487/RFC6186, March 2011,
<https://www.rfc-editor.org/info/rfc6186>.
[RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
Cheshire, "Internet Assigned Numbers Authority (IANA)
Procedures for the Management of the Service Name and
Transport Protocol Port Number Registry", BCP 165,
RFC 6335, DOI 10.17487/RFC6335, August 2011,
<https://www.rfc-editor.org/info/rfc6335>.
[RFC6570] Gregorio, J., Fielding, R., Hadley, M., Nottingham, M.,
and D. Orchard, "URI Template", RFC 6570,
DOI 10.17487/RFC6570, March 2012,
<https://www.rfc-editor.org/info/rfc6570>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/info/rfc6749>.
[RFC6764] Daboo, C., "Locating Services for Calendaring Extensions
to WebDAV (CalDAV) and vCard Extensions to WebDAV
(CardDAV)", RFC 6764, DOI 10.17487/RFC6764, February 2013,
<https://www.rfc-editor.org/info/rfc6764>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/info/rfc6838>.
[RFC6901] Bryan, P., Ed., Zyp, K., and M. Nottingham, Ed.,
"JavaScript Object Notation (JSON) Pointer", RFC 6901,
DOI 10.17487/RFC6901, April 2013,
<https://www.rfc-editor.org/info/rfc6901>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/info/rfc7231>.
[RFC7493] Bray, T., Ed., "The I-JSON Message Format", RFC 7493,
DOI 10.17487/RFC7493, March 2015,
<https://www.rfc-editor.org/info/rfc7493>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <https://www.rfc-editor.org/info/rfc7525>.
[RFC7617] Reschke, J., "The 'Basic' HTTP Authentication Scheme",
RFC 7617, DOI 10.17487/RFC7617, September 2015,
<https://www.rfc-editor.org/info/rfc7617>.
[RFC7807] Nottingham, M. and E. Wilde, "Problem Details for HTTP
APIs", RFC 7807, DOI 10.17487/RFC7807, March 2016,
<https://www.rfc-editor.org/info/rfc7807>.
[RFC8030] Thomson, M., Damaggio, E., and B. Raymor, Ed., "Generic
Event Delivery Using HTTP Push", RFC 8030,
DOI 10.17487/RFC8030, December 2016,
<https://www.rfc-editor.org/info/rfc8030>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
[RFC8264] Saint-Andre, P. and M. Blanchet, "PRECIS Framework:
Preparation, Enforcement, and Comparison of
Internationalized Strings in Application Protocols",
RFC 8264, DOI 10.17487/RFC8264, October 2017,
<https://www.rfc-editor.org/info/rfc8264>.
[RFC8291] Thomson, M., "Message Encryption for Web Push", RFC 8291,
DOI 10.17487/RFC8291, November 2017,
<https://www.rfc-editor.org/info/rfc8291>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[RFC8615] Nottingham, M., "Well-Known Uniform Resource Identifiers
(URIs)", RFC 8615, DOI 10.17487/RFC8615, May 2019,
<https://www.rfc-editor.org/info/rfc8615>.
10.2. Informative References
[RFC8246] McManus, P., "HTTP Immutable Responses", RFC 8246,
DOI 10.17487/RFC8246, September 2017,
<https://www.rfc-editor.org/info/rfc8246>.
Authors' Addresses
Neil Jenkins
Fastmail
PO Box 234, Collins St. West
Melbourne, VIC 8007
Australia
Email: neilj@fastmailteam.com
URI: https://www.fastmail.com
Chris Newman
Oracle
440 E. Huntington Dr., Suite 400
Arcadia, CA 91006
United States of America
Email: chris.newman@oracle.com