Independent Submission K. Murchison
Internet-Draft FastMail
Intended status: Standards Track May 29, 2018
Expires: November 30, 2018
A JSON Meta Application Protocol (JMAP) Subprotocol for WebSocket
draft-murchison-jmap-websocket-00
Abstract
This document defines a binding for the JSON Meta Application
Protocol (JMAP) over a WebSocket transport layer. A WebSocket
binding for JMAP provides higher performance than the current HTTP
binding for JMAP.
Open Issues
o Discovering support for JMAP over WebSocket.
o Should we allow push notifications over the WS connection?
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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material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 30, 2018.
Copyright Notice
Copyright (c) 2018 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
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carefully, as they describe your rights and restrictions with respect
to this document.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 2
3. JMAP Subprotocol . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Handshake . . . . . . . . . . . . . . . . . . . . . . . . 3
3.2. WebSocket Messages . . . . . . . . . . . . . . . . . . . 3
3.3. Examples . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Discovering Support for JMAP over WebSocket . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7.1. Registration of the WebSocket JMAP Sub-Protocol . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 8
8.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
JMAP over HTTP 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.
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.
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3. 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 and responses through a WebSocket connection. Binary data
MUST NOT be uploaded or downloaded through a WebSocket JMAP
connection.
3.1. 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
[I-D.ietf-httpbis-h2-websockets]).
Regardless of the method used for the WebSocket handshake, the client
MUST make an authenticated [RFC7235] HTTP request on the JMAP
'apiURL' (see Section 2 of [I-D.ietf-jmap-core]), 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 and
responses. Messages other than JMAP API requests and responses 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.
3.2. 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 (see Section 3.4 of
[I-D.ietf-jmap-core]) when sent from the server to the client.
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3.3. Examples
The following examples show WebSocket JMAP handshakes and a
subsequent JMAP for Mail [I-D.ietf-jmap-mail] request and response.
The examples assume that the JMAP 'apiURL' has been advertised in the
JMAP Session object as '/jmap/'. Note that folding of header fields
is for editorial purposes only.
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WebSocket JMAP handshake via HTTP/1.1 which also negotiates
compression [RFC7692]:
[[ From Client ]] [[ From Server ]]
GET /jmap/ HTTP/1.1
Host: server.example.com
Upgrade: websocket
Connection: Upgrade
Authorization: Zm9vOmJhcg==
Sec-WebSocket-Key:
dGhlIHNhbXBsZSBub25jZQ==
Sec-WebSocket-Protocol: jmap
Sec-WebSocket-Version: 13
Sec-Websocket-Extensions:
permessage-deflate
Origin: http://www.example.com
HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept:
s3pPLMBiTxaQ9kYGzzhZRbK+xOo=
Sec-WebSocket-Protocol: jmap
Sec-Websocket-Extensions:
permessage-deflate
[WebSocket connection established]
{
"using": [ "urn:ietf:params:jmap:core",
"urn:ietf:params:jmap:mail" ],
"methodCalls": [
...
]
}
{
"methodResponses": [
...
]
}
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WebSocket JMAP handshake on a HTTP/2 stream:
[[ From Client ]] [[ From Server ]]
SETTINGS
SETTINGS_ENABLE_CONNECT_PROTOCOL = 1
HEADERS + END_HEADERS
:method = CONNECT
:protocol = websocket
:scheme = https
:path = /jmap/
:authority = server.example.com
authorization = Zm9vOmJhcg==
sec-websocket-protocol = jmap
sec-websocket-version = 13
origin = http://www.example.com
HEADERS + END_HEADERS
:status = 200
sec-websocket-protocol = jmap
[WebSocket connection established]
DATA
{
"using": [ "urn:ietf:params:jmap:core",
"urn:ietf:params:jmap:mail" ],
"methodCalls": [
...
]
}
DATA
{
"methodResponses": [
...
]
}
4. Discovering Support for JMAP over WebSocket
TODO
o Do we define a new capability for the Session resource?
o Do we simply return an Upgrade:websocket header field in HTTP/1.1
responses to API requests?
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o How would we advertise via HTTP/2 protocol as Alt-Svc is per
origin, NOT per-source?
5. Security Considerations
TODO
6. Privacy Considerations
TODO
7. IANA Considerations
7.1. Registration of the WebSocket JMAP Sub-Protocol
This specification requests IANA to register the WebSocket JMAP sub-
protocol 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)
8. References
8.1. Normative References
[I-D.ietf-httpbis-h2-websockets]
McManus, P., "Bootstrapping WebSockets with HTTP/2",
draft-ietf-httpbis-h2-websockets-05 (work in progress),
May 2018.
[I-D.ietf-jmap-core]
Jenkins, N., "JSON Meta Application Protocol", draft-ietf-
jmap-core-05 (work in progress), May 2018.
[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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[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>.
8.2. Informative References
[I-D.ietf-jmap-mail]
Jenkins, N., "JMAP for Mail", draft-ietf-jmap-mail-05
(work in progress), May 2018.
[RFC7692] Yoshino, T., "Compression Extensions for WebSocket",
RFC 7692, DOI 10.17487/RFC7692, December 2015,
<https://www.rfc-editor.org/info/rfc7692>.
[1] https://tools.ietf.org/html/bcp14
Author's Address
Kenneth Murchison
FastMail US LLC
Email: murch@fastmailteam.com
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