Use of the Prefer Header Field in Web Distributed Authoring and Versioning (WebDAV)
draft-murchison-webdav-prefer-03
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 8144.
|
|
|---|---|---|---|
| Author | Kenneth Murchison | ||
| Last updated | 2013-05-17 | ||
| RFC stream | (None) | ||
| Formats | |||
| Reviews |
GENART Last Call review
(of
-13)
by Stewart Bryant
Ready w/nits
GENART Last Call review
(of
-11)
by Stewart Bryant
Ready w/issues
|
||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | Became RFC 8144 (Proposed Standard) | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-murchison-webdav-prefer-03
Independent Submission K. Murchison
Internet-Draft CMU
Updates: 3253, 4791, 4918, 5689, 5995 (if approved) May 17, 2013
Intended status: Standards Track
Expires: November 18, 2013
Use of the Prefer Header Field in Web Distributed Authoring and
Versioning (WebDAV)
draft-murchison-webdav-prefer-03
Abstract
This specification defines how the HTTP Prefer header can be used by
a WebDAV client to request that certain behaviors be employed by a
server while constructing a response to a successful request.
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 http://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 November 18, 2013.
Copyright Notice
Copyright (c) 2013 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
(http://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.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 3
2. Reducing WebDAV Response Verbosity with
"return=minimal" . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Minimal PROPFIND Response . . . . . . . . . . . . . . . . 4
2.1.1. Example: Typical PROPFIND request/response . . . . . 4
2.1.2. Example: Minimal PROPFIND request/response . . . . . 5
2.1.3. Example: Minimal PROPFIND request/response with an
empty DAV:propstat element . . . . . . . . . . . . . 6
2.2. Minimal REPORT Response . . . . . . . . . . . . . . . . . 7
2.2.1. Example: Typical REPORT request/response . . . . . . 8
2.2.2. Example: Minimal REPORT request/response . . . . . . 9
2.3. Minimal PROPPATCH Response . . . . . . . . . . . . . . . 11
2.3.1. Example: Typical PROPPATCH request/response . . . . . 11
2.3.2. Example: Minimal PROPPATCH request/response . . . . . 12
2.4. Minimal MKCALENDAR / MKCOL Response . . . . . . . . . . . 13
2.4.1. Example: Verbose MKCOL request/response . . . . . . . 13
2.4.2. Example: Minimal MKCOL request/response . . . . . . . 14
3. Reducing WebDAV Round-Trips with
"return=representation" . . . . . . . . . . . . . . . . . . . 15
3.1. Example: Typical resource creation and retrieval
via POST + GET . . . . . . . . . . . . . . . . . . . . . 15
3.2. Example: Streamlined resource creation and
retrieval via POST . . . . . . . . . . . . . . . . . . . 17
4. The "depth-noroot" Processing Preference . . . . . . . . . . 19
4.1. Example: Typical PROPFIND request/response with Depth:1 20
4.2. Example: PROPFIND request/response with Depth:1
and Prefer:depth-noroot . . . . . . . . . . . . . . . . . 21
5. Implementation Status . . . . . . . . . . . . . . . . . . . . 23
5.1. Cyrus . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.2. Calendar and Contacts Server . . . . . . . . . . . . . . 23
5.3. Bedework . . . . . . . . . . . . . . . . . . . . . . . . 23
5.4. DAViCal . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.5. CalDAVTester . . . . . . . . . . . . . . . . . . . . . . 24
6. Security Considerations . . . . . . . . . . . . . . . . . . . 24
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 24
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
9.1. Normative References . . . . . . . . . . . . . . . . . . 25
9.2. Informative References . . . . . . . . . . . . . . . . . 26
Appendix A. The Brief and Extended Depth Request Header Fields . 26
Appendix B. Open Issues . . . . . . . . . . . . . . . . . . . . 26
Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 27
C.1. Since -02 . . . . . . . . . . . . . . . . . . . . . . . . 27
C.2. Since -01 . . . . . . . . . . . . . . . . . . . . . . . . 27
C.3. Since -00 . . . . . . . . . . . . . . . . . . . . . . . . 27
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C.4. Since CalConnect XXIV . . . . . . . . . . . . . . . . . . 28
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 28
1. Introduction
[I-D.snell-http-prefer] defines the HTTP Prefer request header field
and the "return=minimal" preference which indicates that a client
wishes for the server to return a minimal response to a successful
request, but states that what constitutes an appropriate minimal
response is left solely to the discretion of the server. Section 2
of this specification defines precisely what is expected of a server
when constructing minimal responses to successful WebDAV [RFC4918]
requests.
[I-D.snell-http-prefer] also defines the "return=representaion"
preference which indicates that a client wishes for the server to
include an entity representing the current state of the resource in
the response to a successful request. The behavior of this
preference with WebDAV [RFC4918] requests needs no further
clarification, but Section 3 of this specification makes
recommendations on when it should be used by clients.
Finally, Section 4 of this specifcation defines the "depth-noroot"
preference that can be used with WebDAV [RFC4918] methods that
support the "Depth" header field..
1.1. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
This document references XML elements types in the "DAV:" namespace
outside of the context of an XML fragment. When doing so, the string
"DAV:" will be prepended to the XML element type.
2. Reducing WebDAV Response Verbosity with "return=minimal"
Some payload bodies in responses to WebDAV [RFC4918] requests, such
as 207 (Multi-Status) [RFC4918] responses, can be quite verbose or
even unnecessary at times. This specification defines how the Prefer
[I-D.snell-http-prefer] request header field, in conjunction with its
"return=minimal" preference, can be used by clients to reduce the
verbosity of such responses by requesting that the server omit those
portions of the response that can be inferred by their absence.
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2.1. Minimal PROPFIND Response
When a PROPFIND [RFC4918] method request contains a Prefer
[I-D.snell-http-prefer] header field with a preference of
"return=minimal", the server SHOULD omit all DAV:propstat XML
elements containing a DAV:status XML element of value 404 (Not Found)
[I-D.ietf-httpbis-p2-semantics] from the 207 (Multi-Status) [RFC4918]
response. If the omission of such a DAV:propstat element would
result in a DAV:response XML element containing zero DAV:propstat
elements, then the server MUST substitute a DAV:propstat element
consisting of an empty DAV:prop element and a DAV:status element of
value 200 (OK) [I-D.ietf-httpbis-p2-semantics] in its place.
2.1.1. Example: Typical PROPFIND request/response
This example tries to fetch an unknown property from a
CARDDAV:addressbook [RFC6352] collection.
>> Request <<
PROPFIND /container/ HTTP/1.1
Host: carddav.example.com
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
<?xml version="1.0" encoding="UTF-8"?>
<D:propfind xmlns:D="DAV:" xmlns:X="http://ns.example.com/foobar/">
<D:prop>
<D:resourcetype/>
<X:foobar/>
</D:prop>
</D:propfind>
>> Response <<
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HTTP/1.1 207 Multi-Status
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
Vary: Prefer
<?xml version="1.0" encoding="utf-8"?>
<D:multistatus xmlns:D="DAV:" xmlns:X="http://ns.example.com/foobar/"
xmlns:C="urn:ietf:params:xml:ns:carddav">
<D:response>
<D:href>/container/</D:href>
<D:propstat>
<D:prop>
<D:resourcetype>
<D:collection/>
<C:addressbook/>
</D:resourcetype>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<X:foobar/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
</D:multistatus>
2.1.2. Example: Minimal PROPFIND request/response
This example tries to fetch an unknown property from a
CARDDAV:addressbook [RFC6352] collection.
>> Request <<
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PROPFIND /container/ HTTP/1.1
Host: carddav.example.com
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
Prefer: return=minimal
<?xml version="1.0" encoding="UTF-8"?>
<D:propfind xmlns:D="DAV:" xmlns:X="http://ns.example.com/foobar/">
<D:prop>
<D:resourcetype/>
<X:foobar/>
</D:prop>
</D:propfind>
>> Response <<
HTTP/1.1 207 Multi-Status
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
Preference-Applied: return=minimal
Vary: Prefer
<?xml version="1.0" encoding="utf-8"?>
<D:multistatus xmlns:D="DAV:" xmlns:C="urn:ietf:params:xml:ns:carddav">
<D:response>
<D:href>/container/</D:href>
<D:propstat>
<D:prop>
<D:resourcetype>
<D:collection/>
<C:addressbook/>
</D:resourcetype>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
2.1.3. Example: Minimal PROPFIND request/response with an empty
DAV:propstat element
This example tries to fetch an unknown property from a
CARDDAV:addressbook [RFC6352] collection.
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>> Request <<
PROPFIND /container/ HTTP/1.1
Host: carddav.example.com
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
Prefer: return=minimal
<?xml version="1.0" encoding="UTF-8"?>
<D:propfind xmlns:D="DAV:" xmlns:X="http://ns.example.com/foobar/">
<D:prop>
<X:foobar/>
</D:prop>
</D:propfind>
>> Response <<
HTTP/1.1 207 Multi-Status
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
Preference-Applied: return=minimal
Vary: Prefer
<?xml version="1.0" encoding="utf-8"?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>/container/</D:href>
<D:propstat>
<D:prop/>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
2.2. Minimal REPORT Response
When a REPORT [RFC3253] method request, whose report type results in
a 207 (Multi-Status) [RFC4918] response, contains a Prefer header
field with a preference of "return=minimal", the server SHOULD omit
all DAV:propstat XML elements containing a DAV:status XML element of
value 404 (Not Found) [I-D.ietf-httpbis-p2-semantics] from the 207
(Multi-Status) [RFC4918] response. If the omission of such a
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DAV:propstat element would result in a DAV:response XML element
containing zero DAV:propstat elements, then the server MUST
substitute a DAV:propstat element consisting of an empty DAV:prop
element and a DAV:status element of value 200 (OK)
[I-D.ietf-httpbis-p2-semantics] in its place.
2.2.1. Example: Typical REPORT request/response
This example uses the CALDAV:calendar-multiget [RFC4791] REPORT type.
>> Request <<
REPORT /murch/work/ HTTP/1.1
Host: caldav.example.com
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-multiget xmlns:C="urn:ietf:params:xml:ns:caldav"
xmlns:D="DAV:"
xmlns:X="http://ns.example.com/foobar/">
<D:prop>
<D:getetag/>
<X:foobar/>
</D:prop>
<D:href>/murch/work/abc.ics</D:href>
<D:href>/murch/work/qrs.ics</D:href>
<D:href>/murch/work/xyz.ics</D:href>
</C:calendar-multiget>
>> Response <<
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HTTP/1.1 207 Multi-Status
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
Vary: Prefer
<?xml version="1.0" encoding="utf-8"?>
<D:multistatus xmlns:D="DAV:"
xmlns:X="http://ns.example.com/foobar/">
<D:response>
<D:href>/murch/work/abc.ics</D:href>
<D:propstat>
<D:prop>
<D:getetag>"jahsd823ru"</D:getetag>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<X:foobar/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>/murch/work/qrs.ics</D:href>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:response>
<D:href>/murch/work/xyz.ics</D:href>
<D:propstat>
<D:prop>
<D:getetag>"p08ulkj"</D:getetag>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<X:foobar/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
</D:multistatus>
2.2.2. Example: Minimal REPORT request/response
This example uses the CALDAV:calendar-multiget [RFC4791] REPORT type.
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>> Request <<
REPORT /murch/work/ HTTP/1.1
Host: caldav.example.com
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
Prefer: return=minimal
<?xml version="1.0" encoding="utf-8" ?>
<C:calendar-multiget xmlns:C="urn:ietf:params:xml:ns:caldav"
xmlns:D="DAV:"
xmlns:X="http://ns.example.com/foobar/">
<D:prop>
<D:getetag/>
<X:foobar/>
</D:prop>
<D:href>/murch/work/abc.ics</D:href>
<D:href>/murch/work/qrs.ics</D:href>
<D:href>/murch/work/xyz.ics</D:href>
</C:calendar-multiget>
>> Response <<
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HTTP/1.1 207 Multi-Status
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
Preference-Applied: return=minimal
Vary: Prefer
<?xml version="1.0" encoding="utf-8"?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>/murch/work/abc.ics</D:href>
<D:propstat>
<D:prop>
<D:getetag>"jahsd823ru"</D:getetag>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>/murch/work/qrs.ics</D:href>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:response>
<D:href>/murch/work/xyz.ics</D:href>
<D:propstat>
<D:prop>
<D:getetag>"p08ulkj"</D:getetag>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
2.3. Minimal PROPPATCH Response
When a PROPPATCH [RFC4918] request contains a Prefer
[I-D.snell-http-prefer] header field with a preference of
"return=minimal", and all instructions are processed successfully,
the server SHOULD return a 200 (OK) [I-D.ietf-httpbis-p2-semantics]
response with an empty (zero-length) message body instead of a 207
(Multi-Status) [RFC4918] response.
2.3.1. Example: Typical PROPPATCH request/response
>> Request <<
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PROPPATCH /container/ HTTP/1.1
Host: webdav.example.com
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8"?>
<D:propertyupdate xmlns:D="DAV:">
<D:set>
<D:prop>
<D:displayname>My Container</D:displayname>
</D:prop>
</D:set>
</D:propertyupdate>
>> Response <<
HTTP/1.1 207 Multi-Status
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8"?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>/container/</D:href>
<D:propstat>
<D:prop>
<D:displayname/>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
2.3.2. Example: Minimal PROPPATCH request/response
>> Request <<
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PROPPATCH /container/ HTTP/1.1
Host: webdav.example.com
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
Prefer: return=minimal
<?xml version="1.0" encoding="utf-8"?>
<D:propertyupdate xmlns:D="DAV:">
<D:set>
<D:prop>
<D:displayname>My Container</D:displayname>
</D:prop>
</D:set>
</D:propertyupdate>
>> Response <<
HTTP/1.1 200 OK
Content-Length: 0
Preference-Applied: return=minimal
2.4. Minimal MKCALENDAR / MKCOL Response
Both the MKCALENDAR [RFC4791] and Extended MKCOL [RFC5689]
specifications indicate that a server MAY return a message body in
response to a successful request. This specification explicitly
defines the intended behavior in the presence of the Prefer
[I-D.snell-http-prefer] header field.
When a MKCALENDAR or an Extended MKCOL request contains a Prefer
header field with a preference of "return=minimal", and the
collection is created with all requested properties being set
successfully, the server SHOULD return a 201 (Created)
[I-D.ietf-httpbis-p2-semantics] response with an empty (zero-length)
message body.
2.4.1. Example: Verbose MKCOL request/response
>> Request <<
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MKCOL /container/ HTTP/1.1
Host: webdav.example.com
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8"?>
<D:mkcol xmlns:D="DAV:">
<D:set>
<D:prop>
<D:displayname>My Container</D:displayname>
</D:prop>
</D:set>
</D:mkcol>
>> Response <<
HTTP/1.1 201 Created
Cache-Control: no-cache
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8"?>
<D:mkcol-response xmlns:D="DAV:">
<D:propstat>
<D:prop>
<D:displayname/>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:mkcol-response>
2.4.2. Example: Minimal MKCOL request/response
>> Request <<
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MKCOL /container/ HTTP/1.1
Host: webdav.example.com
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
Prefer: return=minimal
<?xml version="1.0" encoding="utf-8"?>
<D:mkcol xmlns:D="DAV:">
<D:set>
<D:prop>
<D:displayname>My Container</D:displayname>
</D:prop>
</D:set>
</D:mkcol>
>> Response <<
HTTP/1.1 201 Created
Cache-Control: no-cache
Content-Length: 0
Preference-Applied: return=minimal
3. Reducing WebDAV Round-Trips with "return=representation"
The PUT, COPY, MOVE, [RFC4918] and POST [RFC5995] methods can be used
to create or update a resource. In some instances, such as with
CalDAV Scheduling [RFC6638], the created or updated resource
representation may differ from the representation sent in the body of
the request or referenced by the effective request URI. In cases
where the client would normally issue a subsquent GET request to
retrieve the current representation of the resource, the client
SHOULD instead include a Prefer header field with the
"return=representation" preference in the PUT, COPY, MOVE, or POST
request. By doing this, the client can coalesce the create/update
and retrieve operations into one round-trip rather than two. An
additional benefit of using "return=representation" in such a request
is that the client will know that any changes to the resource were
produced by the server rather than a concurrent client, thus
providing a level of atomicity to the operation.
3.1. Example: Typical resource creation and retrieval via POST + GET
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>> Request <<
POST /murch/work;add-member/ HTTP/1.1
Host: caldav.example.com
Content-Type: text/calendar; charset=utf-8
Content-Length: xxxx
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
UID:CD87465FA
SEQUENCE:0
DTSTAMP:20120602T185254Z
DTSTART:20120602T160000Z
DTEND:20120602T170000Z
TRANSP:OPAQUE
SUMMARY:Lunch
ORGANIZER;CN="Ken Murchison":mailto:murch@example.com
ATTENDEE;CN="Ken Murchison";CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED:
mailto:murch@example.com
ATTENDEE;CN="John Doe";CUTYPE=INDIVIDUAL;PARTSTAT
=NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:jdoe@
example.com
END:VEVENT
END:VCALENDAR
>> Response <<
HTTP/1.1 201 Created
Location: /murch/work/abc.ics
Content-Length: 0
ETag: "nahduyejc"
Schedule-Tag: "jfd84hgbcn"
>> Request <<
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GET /murch/work/abc.ics HTTP/1.1
Host: caldav.example.com
>> Response <<
HTTP/1.1 200 OK
Content-Type: text/calendar; charset=utf-8
Content-Length: xxxx
ETag: "nahduyejc"
Schedule-Tag: "jfd84hgbcn"
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Server//EN
BEGIN:VEVENT
UID:CD87465FA
SEQUENCE:0
DTSTAMP:20120602T185300Z
DTSTART:20120602T160000Z
DTEND:20120602T170000Z
TRANSP:OPAQUE
SUMMARY:Lunch
ORGANIZER;CN="Ken Murchison":mailto:murch@example.com
ATTENDEE;CN="Ken Murchison";CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED:
mailto:murch@example.com
ATTENDEE;CN="John Doe";CUTYPE=INDIVIDUAL;PARTSTAT
=NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE;SCHEDULE-STATUS=
1.2:mailto:jdoe@example.com
END:VEVENT
END:VCALENDAR
3.2. Example: Streamlined resource creation and retrieval via POST
>> Request <<
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POST /murch/work;add-member/ HTTP/1.1
Host: caldav.example.com
Content-Type: text/calendar; charset=utf-8
Content-Length: xxxx
Prefer: return=representation
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Client//EN
BEGIN:VEVENT
UID:CD87465FA
SEQUENCE:0
DTSTAMP:20120602T185254Z
DTSTART:20120602T160000Z
DTEND:20120602T170000Z
TRANSP:OPAQUE
SUMMARY:Lunch
ORGANIZER;CN="Ken Murchison":mailto:murch@example.com
ATTENDEE;CN="Ken Murchison";CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED:
mailto:murch@example.com
ATTENDEE;CN="John Doe";CUTYPE=INDIVIDUAL;PARTSTAT
=NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE:mailto:jdoe@
example.com
END:VEVENT
END:VCALENDAR
>> Response <<
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HTTP/1.1 201 Created
Location: /murch/work/abc.ics
Content-Type: text/calendar; charset=utf-8
Content-Length: xxxx
Content-Location: /murch/work/abc.ics
ETag: "nahduyejc"
Schedule-Tag: "jfd84hgbcn"
Preference-Applied: return=representation
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Corp.//CalDAV Server//EN
BEGIN:VEVENT
UID:CD87465FA
SEQUENCE:0
DTSTAMP:20120602T185300Z
DTSTART:20120602T160000Z
DTEND:20120602T170000Z
TRANSP:OPAQUE
SUMMARY:Lunch
ORGANIZER;CN="Ken Murchison":mailto:murch@example.com
ATTENDEE;CN="Ken Murchison";CUTYPE=INDIVIDUAL;PARTSTAT=ACCEPTED:
mailto:murch@example.com
ATTENDEE;CN="John Doe";CUTYPE=INDIVIDUAL;PARTSTAT
=NEEDS-ACTION;ROLE=REQ-PARTICIPANT;RSVP=TRUE;SCHEDULE-STATUS=
1.2:mailto:jdoe@example.com
END:VEVENT
END:VCALENDAR
4. The "depth-noroot" Processing Preference
The "depth-noroot" preference indicates that the client wishes for
the server to exclude the target (root) resource from processing by
the WebDAV method and only apply the WebDAV method to the target
resource's subordinate resources.
depth-noroot = "depth-noroot"
This preference is only intended to be used with WebDAV methods whose
definitions explicitly provide support for the Depth [RFC4918] header
field. Furthermore, this preference only applies when the Depth
header field has a value of "1" or "infinity" (either implicitly or
explicitly).
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The "depth-noroot" preference MAY be used in conjunction with the
"return=minimal" preference in a single request.
4.1. Example: Typical PROPFIND request/response with Depth:1
This example fetches the DAV:sync-token [RFC6578] property for a
collection and its child collections.
>> Request <<
PROPFIND /murch/ HTTP/1.1
Host: dav.example.com
Content-Type: text/xml
Content-Length: xxx
Depth: 1
<?xml version="1.0" encoding="UTF-8"?>
<D:propfind xmlns:D="DAV:">
<D:prop>
<D:sync-token/>
</D:prop>
</D:propfind>
>> Response <<
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HTTP/1.1 207 Multi-Status
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
<?xml version="1.0" encoding="utf-8"?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>/murch/</D:href>
<D:propstat>
<D:prop>
<D:sync-token>http://example.com/ns/sync/2216-2</D:sync-token>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>/murch/work/</D:href>
<D:propstat>
<D:prop>
<D:sync-token>http://example.com/ns/sync/2136-34</D:sync-token>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>/murch/home/</D:href>
<D:propstat>
<D:prop>
<D:sync-token>http://example.com/ns/sync/2141-19</D:sync-token>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
4.2. Example: PROPFIND request/response with Depth:1 and Prefer:depth-
noroot
This example fetches the DAV:sync-token [RFC6578] property for just
the child collections.
>> Request <<
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PROPFIND /murch/ HTTP/1.1
Host: dav.example.com
Content-Type: text/xml
Content-Length: xxx
Depth: 1
Prefer: depth-noroot
<?xml version="1.0" encoding="UTF-8"?>
<D:propfind xmlns:D="DAV:">
<D:prop>
<D:sync-token/>
</D:prop>
</D:propfind>
>> Response <<
HTTP/1.1 207 Multi-Status
Content-Type: application/xml; charset=utf-8
Content-Length: xxxx
Preference-Applied: depth-noroot
Vary: Prefer
<?xml version="1.0" encoding="utf-8"?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>/murch/work/</D:href>
<D:propstat>
<D:prop>
<D:sync-token>http://example.com/ns/sync/2136-34</D:sync-token>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>/murch/home/</D:href>
<D:propstat>
<D:prop>
<D:sync-token>http://example.com/ns/sync/2141-19</D:sync-token>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
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5. Implementation Status
[RFC Editor: before publication please remove this section and the
reference to [I-D.sheffer-running-code]]
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in
[I-D.sheffer-running-code]. According to [I-D.sheffer-running-code],
"this will allow reviewers and working groups to assign due
consideration to documents that have the benefit of running code, by
considering the running code as evidence of valuable experimentation
and feedback that has made the implemented protocols more mature. It
is up to the individual working groups to use this information as
they see fit".
5.1. Cyrus
The open source Cyrus [1] project is a highly scalable enterprise
mail system which also supports calendaring and contacts. This beta
level CalDAV/CardDAV implementation supports all of the preferences
described in this document and successfully interoperates with the
CalDAVTester client implementation described below. This
implementation is freely distributable under a BSD style license from
Computing Services at Carnegie Mellon University [2].
5.2. Calendar and Contacts Server
The open source Calendar and Contacts Server [3] project is a
standards-compliant server implementing the CalDAV and CardDAV
protocols. This production level implementation supports all of the
preferences described in this document and successfully interoperates
with the CalDAVTester client implementation described below. This
implementation is freely distributable under the terms of the Apache
License, Version 2.0 [4].
5.3. Bedework
Bedework [5] is an open-source enterprise calendar system that
supports public, personal, and group calendaring. This production
level implementation supports the "return=minimal" preference
described in this document and successfully interoperates with the
CalDAVTester client implementation described below. This
implementation is freely distributable under the Jasig Licensing
Policy [6].
5.4. DAViCal
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DAViCal [7] is a server for calendar sharing using the CalDAV
protocol. This production level implementation supports the
"return=minimal" preference described in this document and
successfully interoperates with the CalDAVTester client
implementation described below. This implementation is Free Software
[8] distributable under the General Public License [9].
5.5. CalDAVTester
CalDAVTester [10] is an open source test and performance application
designed to work with CalDAV and/or CardDAV servers and tests various
aspects of their protocol handling as well as performance. This
widely used implementation supports all of the preferences described
in this document and successfully interoperates with the server
implementations described above. This implementation is freely
distributable under the terms of the Apache License, Version 2.0
[11].
6. Security Considerations
No new security considerations are introduced by use of the Prefer
header field with WebDAV request methods, beyond those discussed in
[I-D.snell-http-prefer] and those already inherent in those methods.
7. IANA Considerations
The following preference is to be added to the Preferences Registry
defined in [I-D.snell-http-prefer].
o Preference: depth-noroot
o Description: The "depth-noroot" preference indicates that the
client wishes for the server to exclude the target (root) resource
from processing by the WebDAV method and only apply the WebDAV
method to the target resource's subordinate resources.
o Reference: Section 4
o Notes: This preference is only intended to be used with WebDAV
methods whose definitions explicitly provide support for the
"Depth" [RFC4918] header field. Furthermore, this preference only
applies when the "Depth" header field has a value of "1" or
"infinity" (either implicitly or explicitly).
8. Acknowledgements
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The author would like to thank the following individuals for
contributing their ideas and support for writing this specification:
Cyrus Daboo, Helge Hess, Andrew McMillan, and Arnaud Quillaud.
The author would also like to thank the Calendaring and Scheduling
Consortium for advice with this specification, and for organizing
interoperability testing events to help refine it.
9. References
9.1. Normative References
[I-D.ietf-httpbis-p2-semantics]
Fielding, R. and J. Reschke, "Hypertext Transfer Protocol
(HTTP/1.1): Semantics and Content", draft-ietf-
httpbis-p2-semantics-22 (work in progress), February 2013.
[I-D.snell-http-prefer]
Snell, J., "Prefer Header for HTTP", draft-snell-http-
prefer-18 (work in progress), January 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3253] Clemm, G., Amsden, J., Ellison, T., Kaler, C., and J.
Whitehead, "Versioning Extensions to WebDAV
(Web Distributed Authoring and Versioning)", RFC 3253,
March 2002.
[RFC4791] Daboo, C., Desruisseaux, B., and L.M. Dusseault,
"Calendaring Extensions to WebDAV (CalDAV)", RFC 4791,
March 2007.
[RFC4918] Dusseault, L., "HTTP Extensions for Web Distributed
Authoring and Versioning (WebDAV)", RFC 4918, June 2007.
[RFC5689] Daboo, C., "Extended MKCOL for Web Distributed Authoring
and Versioning (WebDAV)", RFC 5689, September 2009.
[RFC5995] Reschke, J., "Using POST to Add Members to Web Distributed
Authoring and Versioning (WebDAV) Collections", RFC 5995,
September 2010.
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9.2. Informative References
[I-D.sheffer-running-code]
Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: the Implementation Status Section", draft-sheffer-
running-code-04 (work in progress), April 2013.
[MSDN.aa493854]
Microsoft Developer Network, "PROPPATCH Method", June
2006.
[MSDN.aa563501]
Microsoft Developer Network, "Brief Header", June 2006.
[MSDN.aa563950]
Microsoft Developer Network, "Depth Header", June 2006.
[MSDN.aa580336]
Microsoft Developer Network, "PROPFIND Method", June 2006.
[RFC6352] Daboo, C., "CardDAV: vCard Extensions to Web Distributed
Authoring and Versioning (WebDAV)", RFC 6352, August 2011.
[RFC6578] Daboo, C. and A. Quillaud, "Collection Synchronization for
Web Distributed Authoring and Versioning (WebDAV)", RFC
6578, March 2012.
[RFC6638] Daboo, C. and B. Desruisseaux, "Scheduling Extensions to
CalDAV", RFC 6638, June 2012.
Appendix A. The Brief and Extended Depth Request Header Fields
This document is based heavily on the Brief [MSDN.aa563501] and
extended Depth [MSDN.aa563950] request header fields. The behaviors
described in Section 2.1 and Section 2.3 are identical to those
provided by the Brief header field when used with the PROPFIND
[MSDN.aa580336] and PROPPATCH [MSDN.aa493854] methods respectively.
The behavior described in Section 4 is identical to that provided by
the "1,noroot" [MSDN.aa563950] and "infinity,noroot" [MSDN.aa563950]
Depth header field values.
Authors are encouraged to implement the Brief header field
functionality in conjunction with this specification to further
promote interoperability with products that use the Brief header
field exclusively.
Appendix B. Open Issues
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o Do we need a "depth-root" option for use with DAV:sync-
level=infinity? Or is this best addressed with an extension to
[RFC6578]?
o Is the Vary header field necesary in the PROPFIND/REPORT
responses? Are PROPFIND/REPORT results ever cached?
o Does this specification actually update RFC 3253, 4791, 4918,
5689, 5995? The original thought was yes because this draft
updates/alters the behavior of the HTTP methods contained in those
specs. However, the base Prefer draft doesn't state that it
updates RFC 2616 or HTTPbis.
Appendix C. Change Log
[RFC Editor: before publication please remove this section]
C.1. Since -02
o Reintroduced "Updates" to header.
o Added text noting that "return=representation" provides a level of
atomicity to the operation.
o Added "Implementation Status" section.
o Tweaked/corrected some examples..
o Updated HTTPbis references.
C.2. Since -01
o Removed "Updates" from header.
o Fixed some missing/incorrect references.
o Reintroduced Cache-Control:no-cache to MKCOL responses.
C.3. Since -00
o Updated to comply with draft-snell-httpprefer-18.
o Reordered "Minimal REPORT Response" and "Minimal PROPPATCH
Response" sections.
o Added some explanatory text to examples.
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C.4. Since CalConnect XXIV
o Updated references.
o Stated that "depth-noroot" can be used in conjuction with
"return=minimal".
o Added text mentioning that "depth-noroot" is based on the MSDN
"1,noroot" and "infinity,noroot" Depth header values.
o The server behavior required when "return=minimal" would result in
zero DAV:propstat elements has been changed
from:
<?xml version="1.0" encoding="utf-8"?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>/container/</D:href>
<D:status>HTTP/1.1 200 OK</D:status>
</D:response>
</D:multistatus>
to the slightly more verbose:
<?xml version="1.0" encoding="utf-8"?>
<D:multistatus xmlns:D="DAV:">
<D:response>
<D:href>/container/</D:href>
<D:propstat>
<D:prop/>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
</D:response>
</D:multistatus>
Author's Address
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Kenneth Murchison
Carnegie Mellon University
5000 Forbes Avenue
Pittsburgh, PA 15213
US
Email: murch@andrew.cmu.edu
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