JMAP for Quotas
draft-ietf-jmap-quotas-10

JMAP Working Group                                     R.C. Cordier, Ed.
Internet-Draft                                          Linagora Vietnam
Intended status: Standards Track                        30 November 2022
Expires: 3 June 2023

                            JMAP for Quotas
                       draft-ietf-jmap-quotas-10

Abstract

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

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   This Internet-Draft will expire on 3 June 2023.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Notational conventions  . . . . . . . . . . . . . . . . .   2
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Addition to the capabilities object . . . . . . . . . . . . .   3
     2.1.  urn:ietf:params:jmap:quota  . . . . . . . . . . . . . . .   3
   3.  Data types  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.2.  ResourceType  . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Quota . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Quota/get . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.2.  Quota/changes . . . . . . . . . . . . . . . . . . . . . .   6
     4.3.  Quota/query . . . . . . . . . . . . . . . . . . . . . . .   6
     4.4.  Quota/queryChanges  . . . . . . . . . . . . . . . . . . .   7
   5.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  Fetching quotas . . . . . . . . . . . . . . . . . . . . .   7
     5.2.  Requesting latest quota changes . . . . . . . . . . . . .   8
   6.  Push  . . . . . . . . . . . . . . . . . . . . . . . . . . . .   9
   7.  Security considerations . . . . . . . . . . . . . . . . . . .   9
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
     8.1.  JMAP Capability Registration for "quota"  . . . . . . . .  10
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .  10
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   JMAP ([RFC8620] – (U+2013) 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 a user to obtain details about a certain quota.

   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.

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   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.

1.2.  Terminology

   This document reuses the terminology from the core JMAP specification
   established in section 1.6 of [RFC8620].

   The term Quota (when capitalized) is used to refer to the data type
   defined in this document in Section 4 and instance of that data type.

2.  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.

2.1.  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.

3.  Data types

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

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

3.1.  Scope

   The *Scope* data type is used to represent the entities the Quota
   applies to.  It is defined as a "String" with values from the
   following set:

   *  account: The Quota information applies to just the client's
      account

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   *  domain: The Quota information applies to all accounts sharing this
      domain
   *  global: The Quota information applies to all accounts belonging to
      the server

3.2.  ResourceType

   The *ResourceType* data type is used to act as a unit of measure for
   the quota usage.  It is defined as a "String" with values from the
   following set:

   *  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".

4.  Quota

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

   The quota object MUST contain the following fields:

   *  id: "Id"

      The unique identifier for this object.

   *  resourceType: "ResourceType"

      The resource type of the quota as defined in Section 3.2.

   *  used: "UnsignedInt"

      The current usage of the defined quota, using the "resourceType"
      defined as unit of measure.  Computation of this value is handled
      by the server.

   *  limit: "UnsignedInt"

      The hard limit set by this quota, using the "resourceType" defined
      as unit of measure.  Objects in scope may not be created or
      updated if this limit is reached.

   *  scope: "Scope"

      The "Scope" of this quota as defined in Section 3.1.

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   *  name: "String"

      The name of the quota object.  Useful for managing quotas and
      using queries for searching.

   *  dataTypes: "String[]"

      A list of all the type names (e.g., Email, Calendar, etc.) to
      which this quota applies.  This allows to assign quotas to
      distinct or shared data types.  This MAY include data types the
      client does not recognise.  Clients MUST ignore any unknown data
      type in the list.

   The quota object MAY contain the following fields:

   *  warnLimit: "UnsignedInt|null"

      The warn limit set by this quota object, using the "resourceType"
      defined as unit of measure.  It can be used to send a warning to
      an entity about to reach the hard limit soon, but with no action
      taken yet.  If set, it SHOULD be lower than the "softLimit" (if
      present and different than null) and the "limit".

   *  softLimit: "UnsignedInt|null"

      The soft limit set by this quota object, using the "resourceType"
      defined as unit of measure.  It can be used to still allow some
      operations, but refuse some others.  What is allowed or not is up
      to the server.  For example, it could be used for blocking
      outgoing events of an entity (sending emails, creating calendar
      events, ...) while still receiving incoming events (receiving
      emails, receiving calendars events, ...).  If set, it SHOULD be
      higher than the "warnLimit" (if present and different than null)
      but lower than the "limit".

   *  description: "String|null"

      Arbitrary free, human readable, description of this quota.  It
      might be used to explain where the limit comes from and explain
      the entities and data types this quota applies to.  The
      description MUST be encoded in UTF-8 [RFC3629] as described in
      [RFC8620] section 1.5, selected based on an Accept-Language header
      in the request (as defined in [RFC9110], Section 12.5.4) or out-
      of-band information about the user's language/locale.

   The following JMAP methods are supported.

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4.1.  Quota/get

   Standard "/get" method as described in [RFC8620] section 5.1.  The
   _ids_ argument may be "null" to fetch all Quotas of the account at
   once, as demonstrated in this document at Section 5.1.

4.2.  Quota/changes

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

   *  updatedProperties: "String[]|null"

      If only the "used" Quota property has changed since the old state,
      this will be a list containing only that property.  If the server
      is unable to tell if only "used" has changed, it MUST 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.

   This method's usage is demonstrated in this document at Section 5.2.

4.3.  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[]"

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      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 the
   given conditions match, including multiple array elements existing
   within a condition.  If zero properties are specified, it is
   automatically true for all objects.

   The following Quota properties MUST be supported for sorting:

   *  name
   *  used

4.4.  Quota/queryChanges

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

5.  Examples

5.1.  Fetching quotas

   Request fetching all quotas related to an account :

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

   With response :

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   [[ "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": "bob@example.com",
       "description": "Personal account usage",
       "dataTypes" : [ "Mail", "Calendar", "Contact" ]
     }, {
       "id": "3b06df0e-3761-4s74-a92f-74dcc963501x",
       "resourceType": "octets",
       ...
     }, ...],
     "notFound": []
   }, "0" ]]

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:

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   [[ "Quota/changes", {
     "accountId": "u33084183",
     "oldState": "10824",
     "newState": "10826",
     "hasMoreChanges": false,
     "updatedProperties": ["used"],
     "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" ]]

6.  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.

7.  Security considerations

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

   Implementors should be careful to make sure the implementation of the
   extension specified in this document 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 themselves 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).

   Also, revealing domain and global quota counts to all users may cause
   privacy leakage of other sensitive data, or at least the existence of
   other sensitive data.  For example, "user1" is part of a private list
   belonging to the server, so he shouldn't know how many users are in

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   there.  But by comparing the quota count before and after sending a
   message to the list, it could reveal the number of people of the
   list, as the domain or global quota count would go up by the number
   of people subscribed.  Likely to limit those attacks, quotas with
   "domain" or "global" scope should only be visible to the
   administrators of the server and not all users.

8.  IANA Considerations

8.1.  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 7.

9.  Normative References

   [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>.

   [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>.

   [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>.

   [RFC8620]  Jenkins, N. and C. Newman, "The JSON Meta Application
              Protocol (JMAP)", RFC 8620, DOI 10.17487/RFC8620, July
              2019, <https://www.rfc-editor.org/info/rfc8620>.

Author's Address

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   René Cordier (editor)
   Linagora Vietnam
   5 Dien Bien Phu
   Hanoi
   10000
   Vietnam
   Email: rcordier@linagora.com
   URI:   https://linagora.vn

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