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Versions: (draft-murchison-jmap-websocket) 00 01

JMAP                                                        K. Murchison
Internet-Draft                                                  FastMail
Intended status: Standards Track                          March 10, 2019
Expires: September 11, 2019


   A JSON Meta Application Protocol (JMAP) Subprotocol for WebSocket
                      draft-ietf-jmap-websocket-01

Abstract

   This document defines a binding for the JSON Meta Application
   Protocol (JMAP) over a WebSocket transport layer.  The WebSocket
   binding for JMAP provides higher performance than the current HTTP
   binding for JMAP.

Open Issues

   o  Should push over WebSocket make use of the EventSource Last-Event-
      ID request header field (or a similar facility; e.g., as an extra
      query parameter)?  And if so, where would the server state token
      be returned to the user?  As a new property in the StateChange
      object?

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 11, 2019.

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



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   (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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   3
   3.  Discovering Support for JMAP over WebSocket . . . . . . . . .   3
   4.  JMAP Subprotocol  . . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  Handshake . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.2.  WebSocket Messages  . . . . . . . . . . . . . . . . . . .   4
       4.2.1.  JMAP Requests . . . . . . . . . . . . . . . . . . . .   5
       4.2.2.  JMAP Responses  . . . . . . . . . . . . . . . . . . .   5
       4.2.3.  JMAP Request-level Errors . . . . . . . . . . . . . .   5
       4.2.4.  JMAP Push Notifications . . . . . . . . . . . . . . .   5
     4.3.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
     6.1.  Registration of the WebSocket JMAP Subprotocol  . . . . .  10
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  10
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  10
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  11
     8.3.  URIs  . . . . . . . . . . . . . . . . . . . . . . . . . .  11
   Appendix A.  Change History (To be removed by RFC Editor before
                publication) . . . . . . . . . . . . . . . . . . . .  11
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   JMAP [I-D.ietf-jmap-core] over HTTP [RFC7235] requires that every
   JMAP API request be authenticated.  Depending on the type of
   authentication used by the JMAP client and the configuration of the
   JMAP server, authentication could be an expensive operation both in
   time and resources.  In such circumstances, authenticating every JMAP
   API request may harm performance.

   The WebSocket binding for JMAP eliminates this performance hit by
   authenticating just the WebSocket handshake request and having those
   credentials remain in effect for the duration of the WebSocket
   connection.  This binding supports JMAP API requests and responses,
   with optional support for push notifications.




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   Furthermore, the WebSocket binding for JMAP can optionally compress
   [RFC7692] both JMAP API requests and responses.  Although compression
   of HTTP responses is ubiquitous, compression of HTTP requests has
   very low, if any deployment, and therefore isn't a viable option for
   JMAP API requests over HTTP.

2.  Conventions Used in This Document

   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 [1] [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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

3.  Discovering Support for JMAP over WebSocket

   The JMAP capabilities object is returned as part of the standard JMAP
   Session object (see Section 2 of [I-D.ietf-jmap-core]).  Servers
   supporting this specification MUST add a property named
   "urn:ietf:params:jmap:websocket" to the capabilities object.  The
   value of this property is an object which MUST contain the following
   information on server capabilities:

   wsUrl:  "String" The URL to use for initiating a JMAP over WebSocket
      handshake.

   Server support for push notifications over the WebSocket is OPTIONAL.
   A server advertises that it supports push notifications by returning
   the "wsURL" property in URI Template [RFC6570] (level 3) format
   containing the variable "{?types}".  The use of this variable is
   described in Section 4.2.4.

   Example:

   "urn:ietf:params:jmap:websocket": {
     "wsUrl": "/jmap/ws/{?types}"
   }

4.  JMAP Subprotocol

   The term WebSocket subprotocol refers to an application-level
   protocol layered on top of a WebSocket connection.  This document
   specifies the WebSocket JMAP subprotocol for carrying JMAP API
   requests, responses, and optional push notifications through a
   WebSocket connection.  Binary data MUST NOT be uploaded or downloaded



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   through a WebSocket JMAP connection.  Binary data is handled per
   Section 6 of [I-D.ietf-jmap-core]) via a separate HTTP connection or
   stream.

4.1.  Handshake

   The JMAP WebSocket client and JMAP WebSocket server negotiate the use
   of the WebSocket JMAP subprotocol during the WebSocket handshake,
   either via a HTTP/1.1 Upgrade request (see Section 1.3 of [RFC6455])
   or a HTTP/2 Extended CONNECT request (see Section 5 of [RFC8441]).

   Regardless of the method used for the WebSocket handshake, the client
   MUST make an authenticated [RFC7235] HTTP request on the JMAP "wsURL"
   (Section 3), and the client MUST include the value 'jmap' in the list
   of protocols for the 'Sec-WebSocket-Protocol' header field.  The
   reply from the server MUST also contain 'jmap' in its corresponding
   'Sec-WebSocket-Protocol' header field in order for a JMAP subprotocol
   connection to be established.

   If a client receives a handshake response that does not include
   'jmap' in the 'Sec-WebSocket-Protocol' header, then a JMAP
   subprotocol WebSocket connection was not established and the client
   MUST close the WebSocket connection.

   Once the handshake has successfully completed, the WebSocket
   connection is established and can be used for JMAP API requests,
   responses, and optional push notifications.  Other message types MUST
   NOT be transmitted over this connection.

   The credentials used for authenticating the HTTP request to initiate
   the handshake remain in effect for the duration of the WebSocket
   connection.

4.2.  WebSocket Messages

   Data frame messages in the JMAP subprotocol MUST be of the text type
   and contain UTF-8 encoded data.  The messages MUST be in the form of
   a single JMAP Request object (see Section 3.2 of
   [I-D.ietf-jmap-core]) when sent from the client to the server, and in
   the form of a single JMAP Response object, JSON Problem Details
   object, or JMAP StateChange object (see Sections 3.3, 3.5.1, and 7.1
   respectively of [I-D.ietf-jmap-core]) when sent from the server to
   the client.








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4.2.1.  JMAP Requests

   JMAP over WebSocket allows out of order processing of requests,
   thereby requiring a mechanism for the client to correlate requests
   and responses.  To this end, this specification adds one extra
   argument to the request object:

   id:  "String" (default: ) A client-specified identifier for the
      request.

   Additionally, the "maxConcurrentRequests" field in the "capabilities"
   object (see Section 2 of [I-D.ietf-jmap-core]) limits the number of
   inflight requests over the WebSocket.

4.2.2.  JMAP Responses

   This specification adds two extra arguments to the Response object:

   @type:  "String" This MUST be the string "Response".

   requestId:  "String|null" The client-specified identifier in the
      corresponding request.  If "null", no identifier was provided in
      the request.

4.2.3.  JMAP Request-level Errors

   This specification adds two extra arguments to the Problem Details
   object:

   @type:  "String" This MUST be the string "RequestError".

   requestId:  "String|null" The client-specified identifier in the
      corresponding request.  If "null", no identifier was provided in
      the request.

4.2.4.  JMAP Push Notifications

   JMAP over WebSocket servers that support push notifications on the
   WebSocket will advertise a "wsURL" property in URI Template [RFC6570]
   (level 3) format containing the variable "{?types}".

   A client enables push notifications on the server as part of the
   authenticated HTTP request that initiates the WebSocket handshake by
   substituting the appropriate variables:

   types:  This MUST be either:





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      *  A comma-separated list of type names, e.g.  "Email,Mailbox"
         [I-D.ietf-jmap-core].  The server MUST only push changes for
         the types in this list.

      *  The single character: "*".  Changes to all types are pushed.

   All push notifications take the form of a standard StateChange object
   (see Section 7.1 of [I-D.ietf-jmap-core]).

4.3.  Examples

   The following examples show WebSocket JMAP opening handshakes, a JMAP
   Core/echo request and response, and a subsequent closing handshake.
   The examples assume that the JMAP "wsURL" has been advertised in the
   JMAP Session object as "/jmap/ws/{?types}".  Note that folding of
   header fields is for editorial purposes only.

   WebSocket JMAP connection via HTTP/1.1 with push notifications
   enabled:

   [[ From Client ]]                  [[ From Server ]]

   GET /jmap/ws/?types=Email,Mailbox HTTP/1.1
   Host: server.example.com
   Upgrade: websocket
   Connection: Upgrade
   Authorization: Basic Zm9vOmJhcg==
   Sec-WebSocket-Key:
     dGhlIHNhbXBsZSBub25jZQ==
   Sec-WebSocket-Protocol: jmap
   Sec-WebSocket-Version: 13
   Origin: http://www.example.com

                                      HTTP/1.1 101 Switching Protocols
                                      Upgrade: websocket
                                      Connection: Upgrade
                                      Sec-WebSocket-Accept:
                                        s3pPLMBiTxaQ9kYGzzhZRbK+xOo=
                                      Sec-WebSocket-Protocol: jmap

   [WebSocket connection established]

   WS_DATA
   {
     "id": "R1",
     "using": [ "urn:ietf:params:jmap:core" ],
     "methodCalls": [
       [



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         "Core/echo", {
           "hello": true,
           "high": 5
         },
         "b3ff"
       ]
     ]
   }

                                      WS_DATA
                                      {
                                        "@type": "Response",
                                        "requestId": "R1",
                                        "methodResponses": [
                                          [
                                            "Core/echo", {
                                              "hello": true,
                                              "high": 5
                                            },
                                            "b3ff"
                                          ]
                                        ]
                                      }

   WS_DATA
   The quick brown fox jumps
    over the lazy dog.

                                      WS_DATA
                                      {
                                        "@type": "RequestError",
                                        "requestId": "null",
                                        "type":
                                "urn:ietf:params:jmap:error:notJSON",
                                        "status": 400,
                                        "detail":
                                "The request did not parse as I-JSON."
                                      }

                                      WS_DATA
                                      {
                                        "@type": "StateChange",
                                        "changed": {
                                          "a123": {
                                            "Mailbox": "0af7a512ce70",
                                          }
                                        }
                                      }



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   WS_CLOSE

                                      WS_CLOSE

   [WebSocket connection closed]














































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   WebSocket JMAP connection on a HTTP/2 stream which also negotiates
   compression [RFC7692]:

 [[ From Client ]]                  [[ From Server ]]

                                    SETTINGS
                                    SETTINGS_ENABLE_CONNECT_PROTOCOL = 1

 HEADERS + END_HEADERS
 :method = CONNECT
 :protocol = websocket
 :scheme = https
 :path = /jmap/ws/
 :authority = server.example.com
 authorization = Basic Zm9vOmJhcg==
 sec-websocket-protocol = jmap
 sec-websocket-version = 13
 sec-websocket-extensions =
   permessage-deflate
 origin = http://www.example.com

                                    HEADERS + END_HEADERS
                                    :status = 200
                                    sec-websocket-protocol = jmap
                                    sec-websocket-extensions =
                                      permessage-deflate

 [WebSocket connection established]

 DATA
 WS_DATA
 [compressed text]

                                    DATA
                                    WS_DATA
                                    [compressed text]

 ...

 DATA + END_STREAM
 WS_CLOSE

                                    DATA + END_STREAM
                                    WS_CLOSE

 [WebSocket connection closed]
 [HTTP/2 stream closed]




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5.  Security Considerations

   The security considerations for both WebSocket (see Section 10 of
   [RFC6455]) and JMAP (see Section 8 of [I-D.ietf-jmap-core]) apply to
   the WebSocket JMAP subprotocol.

6.  IANA Considerations

6.1.  Registration of the WebSocket JMAP Subprotocol

   This specification requests IANA to register the WebSocket JMAP
   subprotocol under the "WebSocket Subprotocol Name" Registry with the
   following data:

   Subprotocol Identifier:  JMAP

   Subprotocol Common Name:  WebSocket Transport for JMAP (JSON Meta
      Application Protocol)

   Subprotocol Definition:  RFCXXXX (this document)

7.  Acknowledgments

   The author would like to thank the following individuals for
   contributing their ideas and support for writing this specification:
   Neil Jenkins, Robert Mueller, and Chris Newman.

8.  References

8.1.  Normative References

   [I-D.ietf-jmap-core]
              Jenkins, N. and C. Newman, "JSON Meta Application
              Protocol", draft-ietf-jmap-core-14 (work in progress),
              January 2019.

   [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>.

   [RFC6455]  Fette, I. and A. Melnikov, "The WebSocket Protocol",
              RFC 6455, DOI 10.17487/RFC6455, December 2011,
              <https://www.rfc-editor.org/info/rfc6455>.







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   [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>.

   [RFC7235]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Authentication", RFC 7235,
              DOI 10.17487/RFC7235, June 2014,
              <https://www.rfc-editor.org/info/rfc7235>.

   [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>.

   [RFC8441]  McManus, P., "Bootstrapping WebSockets with HTTP/2",
              RFC 8441, DOI 10.17487/RFC8441, September 2018,
              <https://www.rfc-editor.org/info/rfc8441>.

8.2.  Informative References

   [I-D.ietf-jmap-mail]
              Jenkins, N. and C. Newman, "JMAP for Mail", draft-ietf-
              jmap-mail-15 (work in progress), February 2019.

   [RFC7692]  Yoshino, T., "Compression Extensions for WebSocket",
              RFC 7692, DOI 10.17487/RFC7692, December 2015,
              <https://www.rfc-editor.org/info/rfc7692>.

8.3.  URIs

   [1] https://tools.ietf.org/html/bcp14

Appendix A.  Change History (To be removed by RFC Editor before
             publication)

   Changes since ietf-00:

   o  Added text describing advertisement of and selection of optional
      push notifications.

   o  Minor Editorial changes.

   Changes since murchison-02:

   o  Renamed as a JMAP WG document.

   o  Allow out of order processing.




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   o  Allow push notifications.

   o  Modified examples.

   o  Add Security Considerations text.

   o  Minor Editorial changes.

   Changes since murchison-01:

   o  Updated WebSocket over HTTP/2 reference to RFC8144.

   Changes since murchison-00:

   o  Fleshed out section on discovery of support for JMAP over
      WebSocket.

   o  Allow JSON Problem Details objects to be returned by the server
      for toplevel errors.

   o  Mentioned the ability to compress JMAP API requests.

   o  Minor Editorial changes.

Author's Address

   Kenneth Murchison
   FastMail US LLC
   1429 Walnut Street - Suite 1201
   Philadelphia, PA  19102
   USA

   Email: murch@fastmailteam.com
   URI:   http://www.fastmail.com/

















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