Internet-Draft JMAP Quotas August 2022
Cordier Expires 10 February 2023 [Page]
Intended Status:
Standards Track
R.C. Cordier, Ed.
Linagora Vietnam

JMAP for Quotas


This document specifies a data model for handling quotas on accounts with a server using JMAP.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on 10 February 2023.

Table of Contents

1. Introduction

JMAP ([RFC8620] - JSON Meta Application Protocol) is a generic protocol for synchronising data, such as mails, 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 defines a data model for handling quotas over JMAP, allowing you to read and explain quota information.

This specification does not address quota administration, which should be handled by other means.

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.

Type signatures, examples and property descriptions in this document follow the conventions established in section 1.1 of [RFC8620]. Data types defined in the core specification are also used in this document.

Servers MUST support all properties specified for the new data types defined in this document.

1.2. Terminology

The same terminology is used in this document as in the core JMAP specification.

The term Quota (with that specific capitalization) is used to refer to the data type defined in this document and instance of that data type.

1.3. Addition to the capabilities object

The capabilities object is returned as part of the JMAP Session object; see [RFC8620], section 2.

This document defines one additional capability URI.

1.3.1. urn:ietf:params:jmap:quota

This represents support for the Quota data type and associated API methods. Servers supporting this specification MUST add a property called urn:ietf:params:jmap:quota to the capabilities object.

The value of this property is an empty object in both the JMAP session capabilities property and an account's accountCapabilities property.

1.4. Data types

In addition to the standard JSON data types, a couple of additional data types are common to the definition of Quota objects and properties.

1.4.1. Scope

The Scope is a String from an enumeration defined list of values, handled by the server.

It explains the entities this value applies to. Values for the Scope are:

  • account: Applies for this account
  • domain: All accounts of this domain share this part of the quota
  • global: All accounts of this server share this part of the quota

1.4.2. ResourceType

The ResourceType is a String from an enumeration defined list of values, handled by the server.

A resource type is like an unit of measure for the quota usage. Values for the ResourceType are:

  • count: The quota is measured in number of data type objects. For example, a quota can have a limit of 50 Mail objects.
  • octets: The quota is measured in size (in octets). For example, a quota can have a limit of 25000 octets.

1.5. Push

Servers MUST support the JMAP push mechanisms, as specified in [RFC8620] Section 7, to receive notifications when the state changes for the Quota type defined in this specification.

2. Quota

The quota is an object that displays the limit set to an account usage as well as the current usage in regard to that limit.

The quota object MUST contain the following fields:

The quota object MAY contain the following field:

2.1. Quota/get

Standard "/get" method as described in [RFC8620] section 5.1. The ids argument may be null to fetch all at once.

2.2. Quota/changes

Standard "/changes" method as described in [RFC8620] section 5.2 but with one extra argument to the response:

  • updatedProperties: String[]|null If only the "used" Quota properties has changed since the old state, this will be the list of properties that may have changed. If the server is unable to tell if only "used" has changed, it MUST just be null.

Since "used" frequently changes but other properties are generally only changed rarely, the server can help the client optimise data transfer by keeping track of changes to Quota usage separate from other state changes. The updatedProperties array may be used directly via a back-reference in a subsequent Quota/get call in the same request, so only these properties are returned if nothing else has changed.

Servers MAY decide to add other properties to the list that they judge changing frequently.

2.3. Quota/query

This is a standard "/query" method as described in [RFC8620], Section 5.5.

A FilterCondition object has the following properties, any of which may be omitted:

  • name: String The Quota name property contains the given string.
  • scopes: Scope[] The Quota scope property must be in this list to match the condition.
  • resourceTypes: ResourceType[] The Quota resourceType property must be in this list to match the condition.
  • datatypes: String[] The Quota datatypes property must contain the elements in this list to match the condition.

A Quota object matches the FilterCondition if and only if all of the given conditions match. If zero properties are specified, it is automatically true for all objects.

The following Quota properties MUST be supported for sorting:

2.4. Quota/queryChanges

This is a standard "/queryChanges" method as described in [RFC8620], Section 5.6.

2.5. Examples

2.5.1. Fetching quotas

Request fetching all quotas related to an account :

[[ "Quota/get", {
  "accountId": "u33084183",
  "ids": null
}, "0" ]]

With response :

[[ "Quota/get", {
  "accountId": "u33084183",
  "state": "78540",
  "list": [{
    "id": "2a06df0d-9865-4e74-a92f-74dcc814270e",
    "resourceType": "count",
    "used": 1056,
    "warnLimit": 1600,
    "softLimit": 1800,
    "limit": 2000,
    "scope": "account",
    "name": "",
    "description": "Personal account usage",
    "datatypes" : [ "Mail", "Calendar", "Contact" ]
  }, {
    "id": "3b06df0e-3761-4s74-a92f-74dcc963501x",
    "resourceType": "octets",
  }, ...],
  "notFound": []
}, "0" ]]

2.5.2. Requesting latest quota changes

Request fetching the changes for a specific quota:

[[ "Quota/changes", {
  "accountId": "u33084183",
  "sinceState": "10824",
  "maxChanges": 20
}, "0" ],
[ "Quota/get", {
  "accountId": "u33084183",
  "#ids": {
    "resultOf": "0",
    "name": "Quota/changes",
    "path": "/updated"
  "#properties": {
    "resultOf": "0",
    "name": "Quota/changes",
    "path": "/updatedProperties"
}, "1" ]]

With response:

[[ "Quota/changes", {
  "accountId": "u33084183",
  "oldState": "10824",
  "newState": "10826",
  "hasMoreChanges": false,
  "created": [],
  "updated": ["2a06df0d-9865-4e74-a92f-74dcc814270e"],
  "destroyed": []
}, "0" ],
[ "Quota/get", {
  "accountId": "u33084183",
  "state": "10826",
  "list": [{
    "id": "2a06df0d-9865-4e74-a92f-74dcc814270e",
    "used": 1246
  "notFound": []
}, "1" ]]

3. Security considerations

All security considerations of JMAP ([RFC8620]) apply to this specification.

Implementors should be careful to make sure the implementation of that extension does not violate the site's security policy. The resource usage of other users is likely to be considered confidential information and should not be divulged to unauthorized persons.

As for any resource shared across users (for example, a quota with the domain or global scope), a user that can consume the resource can affect the resources available to the other users. For example, a user could spam himself with events and make the shared resource hit the limit and unusable for others (implementors could mitigate that with some rate limiting implementation on the server).

4. IANA Considerations

4.1. JMAP Capability Registration for "quota"

IANA will register the "quota" JMAP Capability as follows:

Capability Name: urn:ietf:params:jmap:quota

Specification document: this document

Intended use: common

Change Controller: IETF

Security and privacy considerations: this document, section 4.

5. Normative References

Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.
Jenkins, N. and C. Newman, "The JSON Meta Application Protocol (JMAP)", RFC 8620, DOI 10.17487/RFC8620, , <>.

Author's Address

René Cordier (editor)
Linagora Vietnam
5 Dien Bien Phu