WebDAV Ordered Collections ProtocolXerox Corporation800 Phillips Road, 105-50CWebsterNY14580jslein@crt.xerox.comUC Santa Cruz, Dept. of Computer Science1156 High StreetSanta CruzCA95064USejw@cse.ucsc.eduIntelligent Markets410 Jessie Street 6th floorSan FranciscoCA94103jrd3@alum.mit.eduFileNet Corporation3565 Harbor BoulevardCosta MesaCA92626-1420cfay@filenet.comIBM ResearchP.O. Box 704Yorktown HeightsNY10598ccjason@us.ibm.comgreenbytes GmbHSalzmannstrasse 152MuensterNW48159Germany+49 251 2807760+49 251 2807761julian.reschke@greenbytes.dehttp://greenbytes.de/tech/webdav/WEBDAV Working Group
This specification extends the WebDAV Distributed Authoring Protocol to
support server-side ordering of collection members. Of particular
interest are orderings that are not based on property values, and so
cannot be achieved using a search protocol's ordering option and cannot
be maintained automatically by the server. Protocol elements are
defined to let clients specify the position in the ordering of each
collection member, as well as the semantics governing the ordering.
Distribution of this document is unlimited. Please send comments to the
Distributed Authoring and Versioning (WebDAV) working group at
w3c-dist-auth@w3.org, which
may be joined by sending a message with subject "subscribe" to
w3c-dist-auth-request@w3.org.
Discussions of the WEBDAV working group are archived at URL:
http://lists.w3.org/Archives/Public/w3c-dist-auth/.
Since this document describes a set of extensions to the WebDAV Distributed
Authoring Protocol , itself an extension to the
HTTP/1.1 protocol, the augmented BNF used here to describe protocol
elements is exactly the same as described in Section 2.1 of HTTP .
Since this augmented BNF uses the basic production rules provided in
Section 2.2 of HTTP, these rules apply to this document as well.
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 .
This specification builds on the collection infrastructure provided by
the WebDAV Distributed Authoring Protocol, adding support for the
server-side ordering of collection members.
There are many scenarios where it is useful to impose an ordering on a
collection at the server, such as expressing a recommended access order,
or a revision history order. The members of a collection might
represent the pages of a book, which need to be presented in order if
they are to make sense. Or an instructor might create a collection of
course readings, which she wants to be displayed in the order they are
to be read.
Orderings may be based on property values, but this is not always the
case. The resources in the collection may not have properties that can
be used to support the desired ordering. Orderings based on properties
can be obtained using a search protocol's ordering option, but orderings
not based on properties cannot. These orderings generally need to be
maintained by a human user.
The ordering protocol defined here focuses on support for such human-maintained
orderings. Its protocol elements allow clients to specify
the position of each collection member in the collection's ordering, as
well as the semantics governing the ordering. The protocol is designed
to allow support to be added in the future for orderings that are
maintained automatically by the server.
The remainder of this document is structured as follows:
defines terminology that will be used throughout the specification.
provides an overview of ordered collections.
describes how to create an ordered collection, and
discusses
how to set a member's position in the ordering of a collection.
explains how to change a collection ordering.
discusses
listing the members of an ordered collection.
through
define the headers, properties, and XML elements needed to support
ordered collections. describes capability discovery.
through discuss security, internationalization, and IANA
considerations. The remaining sections provide supporting information.
The terminology used here follows that in the .
Definitions of the terms resource, Uniform Resource Identifier (URI), and
Uniform Resource Locator (URL) are provided in .
Ordered Collection
A collection for which the results from a PROPFIND request are
guaranteed to be in the order specified for that collection
Unordered Collection
A collection for which the client cannot depend on the
repeatability of the ordering of results from a PROPFIND request
Client-Maintained Ordering
An ordering of collection members that is maintained on the server
based on client requests specifying the position of each
collection member in the ordering
Server-Maintained Ordering
An ordering of collection members that is maintained automatically
by the server, based on a client's choice of ordering semantics
This document uses the terms "precondition" as "postcondition" as defined in
. Servers should report pre-/postcondition failures
as described in section 1.6 of this document.
If a collection is unordered, the client cannot depend on the
repeatability of the ordering of results from a PROPFIND request. By
specifying an ordering for a collection, a client requires the server to
follow that ordering whenever it responds to a PROPFIND request on that
collection.
Server-side orderings may be client-maintained or server-maintained.
For client-maintained orderings, a client must specify the ordering
position of each of the collection's members, either when the member is
added to the collection (using the Position header) or later (using the
ORDERPATCH method). For server-maintained orderings, the server
automatically positions each of the collection's members according to
the ordering semantics. This specification supports only client-maintained
orderings, but is designed to allow future extension to
server-maintained orderings.
A collection that supports ordering is not required to be ordered. It
is up to the client to decide whether a given collection is ordered and,
if so, to specify the semantics to be used for ordering its members.
If a collection is ordered, each of its internal member URIs MUST be in
the ordering exactly once, and the ordering MUST NOT include any URI
that is not an internal member of the collection. The server is
responsible for enforcing these constraints on orderings. The server
MUST remove an internal member URI from the ordering when it is removed
from the collection. The server MUST an internal member URI to the
ordering when it is added to the collection.
Only one ordering can be attached to any collection. Multiple orderings
of the same resources can be achieved by creating multiple collections
referencing those resources, and attaching a different ordering to each
collection.
An ordering is considered to be part of the state of a collection
resource. Consequently, the ordering is the same no matter which URI is
used to access the collection and is protected by locks or access
control constraints on the collection.
Indicates whether the collection is ordered and, if so,
uniquely identifies the semantics of the ordering being
used. May also point to an explanation of the semantics in
human and / or machine-readable form. At a minimum, this
allows human users who add members to the collection to
understand where to position them in the ordering. This
property cannot be set using PROPPATCH. Its value can only
be set by including the Ordered header with a MKCOL request
or by submitting an ORDERPATCH request.
The value DAV:unordered indicates that the collection is not ordered. That
is, the client cannot depend on the repeatability of the ordering of results
from a PROPFIND request.
The value DAV:custom indicates that the collection is
ordered, but the semantics governing the ordering are not
being advertised.
If the value is a DAV:href element, it
contains a URI that uniquely identifies the semantics of the
collection's ordering.
An ordering-aware client interacting with an ordering-unaware
server (e.g., one that is implemented only according to
) SHOULD assume that if a collection does not have the
DAV:orderingtype property, the collection is unordered.
<!ELEMENT orderingtype (unordered | custom | href) >
<!ELEMENT custom EMPTY >
<!ELEMENT unordered EMPTY >
When a collection is created, the client MAY request that it be ordered
and specify the semantics of the ordering by using the new Ordered
header
(defined below)
(defined in )
with a MKCOL request.
For collections that are ordered, the client SHOULD identify the
semantics of the ordering with a URI in the Ordered header, although the
client MAY simply set the header value to DAV:custom to indicate that
the collection is ordered but the semantics of the ordering are not
being advertised. Setting the value to a URI that identifies the
ordering semantics
provides the information a human user or software
package needs to insert new collection members into the ordering
intelligently. Although the URI in the Ordered header MAY point to a
resource that contains a definition of the semantics of the ordering,
clients SHOULD NOT access that resource, in order to avoid overburdening
its server. A value of DAV:unordered in the Ordering header indicates
that the client wants the collection to be unordered. If the Ordered
header is not present, the collection will be unordered.
Every collection that supports ordering MUST have a DAV:orderingtype
property (defined in ),
which indicates whether the
collection is ordered and, if so, identifies the semantics of the
ordering. The server sets the initial value of this property based on
the value of the Ordering header in the MKCOL request, if any. If the
Ordered header is not present, the server sets the value to
DAV:unordered. An ordering-aware client interacting with an ordering-unaware
server (e.g., one that is implemented only according to
) SHOULD assume that if a collection does not have the
DAV:orderingtype property, the collection is unordered.
Additional Marshalling:
Ordered = "Ordered" ":" ("DAV:unordered" | "DAV:custom" | Coded-url)
A value of "DAV:unordered" indicates that the collection is not ordered. A value of
"DAV:custom" indicates that the collection is to be ordered, but the
semantics of the ordering is not being advertised. Any other Coded-url
value indicates that the collection is ordered, and identifies the
semantics of the ordering.
Additional Preconditions:
(DAV:ordered-collections-supported): the server must support ordered
collections where the new collection is to be created.
>> Request:
MKCOL /theNorth/ HTTP/1.1
Host: www.server.org
Ordered: <http://www.server.org/orderings/compass.html>
>> Response:
HTTP/1.1 201 Created
In this example a new, ordered collection was created. Its
DAV:orderingtype property has as its value the URI from the Ordered
header, http://www.server.org/orderings/compass.html. In this case, the
URI identifies the semantics governing a client-maintained ordering. As
new members are added to the collection, clients or end users can use
the semantics to determine where to position the new members in the
ordering.
When a new member is added to a collection with a client-maintained
ordering (for example, with PUT, MKREF, COPY, or MKCOL), its position in
the ordering can be set with the new Position header (defined in ).
The Position header allows the client to specify that an internal
member URI should be first in the collection's ordering, last in the
collection's ordering, immediately before some other internal member URI
in the collection's ordering, or immediately after some other internal
member URI in the collection's ordering.
If the Position request header is not used when adding a member to an
ordered collection, then:
If the request is replacing an existing resource, the server MUST
preserve the present ordering.If the request is adding a new internal member URI to the collection,
the server MUST append the new member to the end of the ordering.
409 (Conflict): Several conditions may cause this response. The request
may specify a position that is before or after a URI that is not an
internal member URI of the collection, or before or after itself. The
request may attempt to specify the new member's position in an unordered
collection.
>> Request:
COPY /~whitehead/dav/spec08.html HTTP/1.1
Host: www.ics.uci.edu
Destination: http://www.xerox.com/~slein/dav/spec08.html
Position: after requirements.html
>> Response:
HTTP/1.1 201 Created
This request resulted in the creation of a new resource at
www.xerox.com/~slein/dav/spec08.html. The Position header in this
example caused the server to set its position in the ordering of the
/~slein/dav/ collection immediately after requirements.html.
>> Request:
MOVE /i-d/draft-webdav-protocol-08.txt HTTP/1.1
Host: www.ics.uci.edu
Destination: http://www.ics.uci.edu/~whitehead/dav/draft-webdav-
protocol-08.txt
Position: first
>> Response:
HTTP/1.1 409 Conflict
In this case, the server returned a 409 (Conflict) status code because
the /~whitehead/dav/ collection is an unordered collection.
Consequently, the server was unable to satisfy the Position header.
The ORDERPATCH method is used to change the ordering semantics of a
collection or to change the order of the collection's members in the
ordering or both.
The ORDERPATCH method changes the ordering semantics of the collection
identified by the Request-URI, based on the value of DAV:orderingtype
submitted in the request entity body.
The ORDERPATCH method alters the ordering of internal member URIs in the
collection identified by the Request-URI, based on instructions in the
ordermember XML elements in the request entity body. The ordermember XML
elements identify the internal member URIs whose positions are to be
changed, and describe their new positions in the ordering. Each new
position can be specified as first in the ordering, last in the
ordering, immediately before some other internal member URI, or
immediately after some other internal member URI.
The server MUST apply the changes in the order they appear in the order
XML element. The server MUST either apply all the changes or apply none
of them. If any error occurs during processing, all executed changes
MUST be undone and a proper error result returned.
If an ORDERPATCH request changes the ordering semantics, but does not
completely specify the order of the collection members, the server MUST
assign a position in the ordering to each collection member for which a
position was not specified. These server-assigned positions MUST all
follow the last one specified by the client. The result is that all
members for which the client specified a position are at the beginning
of the ordering, followed by any members for which the server assigned
positions.
If an ORDERPATCH request does not change the ordering semantics, any
member positions not specified in the request MUST remain unchanged.
Since multiple changes can be requested in a single ORDERPATCH request,
if any problems are encountered, the server MUST return a 207 (Multi-Status)
response, as defined in .
The following are examples of response codes one would expect to be used
in a 207 (Multi-Status) response for this method:
200 (OK): The change in ordering was successfully made.
409 (Conflict): Several conditions may cause this response. The request
may specify a position that is before or after a URI that is not an
internal member URI of the collection, or before or after itself. The
request may attempt to set the positions of members of an unordered
collection.
A request to reposition a collection member at the same place in the
ordering is not an error.
Consider a collection /coll-1/ whose DAV:orderingtype is DAV:whim, with
bindings ordered as follows:
three.html
four.html
one.html
two.html
>> Request:
ORDERPATCH /coll-1/ HTTP/1.1
Host: www.myserver.com
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
<?xml version="1.0" ?>
<d:order xmlns:d="DAV:">
<d:orderingtype>
<d:href>http://www.myserver.com/inorder.ord</d:href>
</d:orderingtype>
<d:ordermember>
<d:href>two.html</d:href>
<d:position>
<d:first/>
</d:position>
</d:ordermember>
<d:ordermember>
<d:href>one.html</d:href>
<d:position>
<d:first/>
</d:position>
</d:ordermember>
<d:ordermember>
<d:href>three.html</d:href>
<d:position>
<d:last/>
</d:position>
</d:ordermember>
<d:ordermember>
<d:href>four.html</d:href>
<d:position>
<d:last/>
</d:position>
</d:ordermember>
</d:order>
>> Response:
HTTP/1.1 200 OK
In this example, after the request has been processed, the collection's
ordering semantics are identified by the URI
http://www.myserver.com/inorder.ord. The value of the collection's
DAV:orderingtype property has been set to this URI. The request also
contains instructions for changing the positions of the collection's
internal member URIs in the ordering to comply with the new ordering
semantics. If href elements are relative URIs, as in this example, they
are interpreted relative to the collection whose ordering is being
modified. The DAV:ordermember elements are required to be processed in
the order they appear in the request. Consequently, two.html is moved
to the beginning of the ordering, and then one.html is moved to the
beginning of the ordering. Then three.html is moved to the end of the
ordering, and finally four.html is moved to the end of the ordering.
After the request has been processed, the collection's ordering is as
follows:
one.html
two.html
three.html
four.html
Consider a collection /coll-1/ with members ordered as follows:
nunavut.map
nunavut.img
baffin.map
baffin.desc
baffin.img
iqaluit.map
nunavut.desc
iqaluit.img
iqaluit.desc
>> Request:
ORDERPATCH /coll-1/ HTTP/1.1
Host: www.nunanet.com
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
<?xml version="1.0" ?>
<d:order xmlns:d="DAV:">
<d:ordermember>
<d:href>nunavut.desc</d:href>
<d:position>
<d:after>
<d:segment>nunavut.map</d:segment>
</d:after>
</d:position>
</d:ordermember>
<d:ordermember>
<d:href>iqaluit.map</d:href>
<d:position>
<d:after>
<d:segment>pangnirtung.img</d:segment>
</d:after>
</d:position>
</d:ordermember>
</d:order>
>> Response:
HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
<?xml version="1.0" ?>
<d:multistatus xmlns:d="DAV:">
<d:response>
<d:href>http://www.nunanet.com/coll-1/nunavut.desc</d:href>
<d:status>HTTP/1.1 424 Failed Dependency</d:status>
</d:response>
<d:response>
<d:href>http://www.nunanet.com/coll-1/iqaluit.map</d:href>
<d:status>HTTP/1.1 409 Conflict</d:status>
<d:responsedescription>pangnirtung.img is not a collection
member.</d:responsedescription>
</d:response>
</d:multistatus>
In this example, the client attempted to position iqaluit.map after a
URI that is not an internal member of the collection /coll-1/. The
server responded to this client error with a 409 (Conflict) status code.
Because ORDERPATCH is an atomic method, the request to reposition
nunavut.desc (which would otherwise have succeeded) failed with a 424
(Failed Dependency) status code.
A PROPFIND request is used to retrieve a listing of the members of an
ordered collection, just as it is used to retrieve a listing of the
members of an unordered collection.
However, when responding to a PROPFIND on an ordered collection, the
server MUST order the response elements according to the ordering
defined on the collection. If a collection is unordered, the client
cannot depend on the repeatability of the ordering of results from a
PROPFIND request.
In a response to a PROPFIND with Depth: infinity, members of different
collections may be interleaved. That is, the server is not required to
do a breadth-first traversal. The only requirement is that the members
of any ordered collection appear in the order defined for the
collection. Thus for the hierarchy illustrated in the following figure,
where collection A is an ordered collection with the ordering B C D,
A
/|\
/ | \
B C D
/ /|\
E F G H
it would be acceptable for the server to return response elements in the
order A B E C F G H D. In this response, B, C, and D appear in the
correct order, separated by members of other collections. Clients can
use a series of Depth: 1 PROPFIND requests to avoid the complexity of
processing Depth: infinity responses based on depth-first traversals.
Suppose a PROPFIND request is submitted to /MyCollection/, which has its
members ordered as follows.
/MyCollection/
lakehazen.html
siorapaluk.html
iqaluit.html
newyork.html
>> Request:
PROPFIND /MyCollection/ HTTP/1.1
Host: www.svr.com
Depth: 1
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" ?>
<D:propfind xmlns:D="DAV:">
<D:prop xmlns:J="http://www.svr.com/jsprops/">
<D:orderingtype/>
<D:resourcetype/>
<J:latitude/>
</D:prop>
</D:propfind>
>> Response:
HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: xxxx
<?xml version="1.0" ?>
<D:multistatus xmlns:D="DAV:"
xmlns:J="http:www.svr.com/jsprops/">
<D:response>
<D:href>http://www.svr.com/MyCollection/</D:href>
<D:propstat>
<D:prop>
<D:orderingtype><D:custom/></D:orderingtype>
<D:resourcetype><D:collection/></D:resourcetype>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<J:latitude/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>http://www.svr.com/MyCollection/lakehazen.html</D:href>
<D:propstat>
<D:prop>
<D:resourcetype/>
<J:latitude>82N</J:latitude>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<D:orderingtype/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href
>http://www.svr.com/MyCollection/siorapaluk.html</D:href>
<D:propstat>
<D:prop>
<D:resourcetype/>
<J:latitude>78N</J:latitude>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<D:orderingtype/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>http://www.svr.com/MyCollection/iqaluit.html</D:href>
<D:propstat>
<D:prop>
<D:resourcetype/>
<J:latitude>62N</J:latitude>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
</D:propstat>
<D:propstat>
<D:prop>
<D:orderingtype/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:response>
<D:response>
<D:href>http://www.svr.com/MyCollection/newyork.html</D:href>
<D:propstat>
<D:prop>
<D:resourcetype/>
<J:latitude>45N</J:latitude>
</D:prop>
<D:status>HTTP/1.1 200 OK</D:status>
<D:propstat>
<D:prop>
<D:orderingtype/>
</D:prop>
<D:status>HTTP/1.1 404 Not Found</D:status>
</D:propstat>
</D:propstat>
</D:response>
</D:multistatus>
In this example, the server responded with a list of the collection
members in the order defined for the collection.
Ordered = "Ordered" ":" ("DAV:unordered" | "DAV:custom" | Coded-url)
The Ordered header may be used with MKCOL to request that the new
collection be ordered and to specify its ordering semantics. A value of
"DAV:unordered" indicates that the collection is not ordered. A value of
"DAV:custom" indicates that the collection is to be ordered, but the
semantics of the ordering is not being advertised. Any other Coded-url
value indicates that the collection is ordered, and identifies the
semantics of the ordering.
Position = "Position" ":" ("first" | "last" |
(("before" | "after") segment))
segment is defined in Section 3.3 of .
The Position header may be used with any method that adds a member to an
ordered collection, to tell the server where in the collection ordering
to position the new member being added to the collection. Examples of
methods that add members to collections are BIND, PUT, COPY, MOVE, etc.
The segment is interpreted relative to the collection to which the new
member is being added.
The server MUST insert the new member into the ordering at the location
specified in the Position header, if one is present (and if the
collection is ordered).
The "first" keyword indicates the new member is put in the beginning
position in the collection's ordering, while "last" indicates the new
member is put in the final position in the collection's ordering. The
"before" keyword indicates the new member is added to the collection's
ordering immediately prior to the position of the member identified in
the segment. Likewise, the "after" keyword indicates the new member is
added to the collection's ordering immediately following the position of
the member identified in the segment.
If the request is replacing an existing resource, and the Position
header is present, the server MUST remove the internal member URI from
its previous position, and then insert it at the requested position.
If an attempt is made to use the Position header on a collection that is
unordered, the server MUST fail the request with a 409 (Conflict) status
code.
orderingtypeDAV:
Indicates whether the collection is ordered and, if so,
uniquely identifies the semantics of the ordering being
used. May also point to an explanation of the semantics in
human and / or machine-readable form. At a minimum, this
allows human users who add members to the collection to
understand where to position them in the ordering. This
property cannot be set using PROPPATCH. Its value can only
be set by including the Ordered header with a MKCOL request
or by submitting an ORDERPATCH request.
The value unordered indicates that the collection is not
ordered. The value custom indicates that the collection is
ordered, but the semantics governing the ordering are not
being advertised. If the value is an href element, it
contains a URI that uniquely identifies the semantics of the
collection's ordering.
<!ELEMENT orderingtype (unordered | custom | href) >
unorderedDAV:
A value of the DAV:orderingtype property that indicates that
the collection is not ordered. That is, the client cannot
depend on the repeatability of the ordering of results from
a PROPFIND request.
<!ELEMENT unordered EMPTY >
customDAV:
A value of the DAV:orderingtype property that indicates that
the collection is ordered, but the semantics of the ordering
are not being advertised.
<!ELEMENT custom EMPTY >
orderDAV:
For use with the new ORDERPATCH method. Describes a change
to be made in a collection's ordering semantics or in the
positions of its members in the ordering or both.
An optional identifier of an ordering semantics for the
collection, followed by a list of changes to be made in the
positions of the members in the collection's ordering.
<!ELEMENT order (orderingtype?, ordermember*) >
ordermemberDAV:
Occurs in the order XML element, and describes the new
position of a single internal member URI in the collection's
ordering.
An href containing a member's path segment, and a
description of its new position in the ordering. The href
XML element is defined in , Section 11.3.
<!ELEMENT ordermember (href, position) >
positionDAV:
Occurs in the ordermember XML element. Describes the new
position in a collection's ordering of one of the members it
contains.
The new position can be described as first in the
collection's ordering, last in the collection's ordering,
immediately before some other collection member, or
immediately after some other collection member.
<!ELEMENT position (first | last | before | after)>
firstDAV:
Occurs in the position XML element. Specifies that the
member should be placed first in the collection's ordering.
<!ELEMENT first EMPTY >
lastDAV:
Occurs in the position XML element. Specifies that the
member should be placed last in the collection's ordering.
<!ELEMENT last EMPTY >
beforeDAV:
Occurs in the position XML element. Specifies that the
member should be placed immediately before the member in the
enclosed segment XML element in the collection's ordering.
URI (relative to the parent collection) of the member
it precedes in the ordering
<!ELEMENT before segment >
afterDAV:
Occurs in the position XML element. Specifies that the
member should be placed immediately after the member in the
enclosed segment XML element in the collection's ordering.
URI (relative to the parent collection) of the member
it follows in the ordering
<!ELEMENT after segment >
segmentDAV:
Identifies a member of a collection, used in the DAV:before
and DAV:after elements, to define one member's position in
a collection ordering relative to another member of the
collection.
segment ; as defined in section 3.3 of .
<!ELEMENT segment (#PCDATA)>
Sections 9.1 and 15 of describe the use of compliance classes
with the DAV header in responses to OPTIONS, to indicate which parts of
the Web Distributed Authoring protocols the resource supports. This
specification defines an OPTIONAL extension to . It defines a
new compliance class, called orderedcoll, for use with the DAV header in
responses to OPTIONS requests. If a collection resource does support
ordering, its response to an OPTIONS request may indicate that it does,
by listing the new ORDERPATCH method as one it supports, and by listing
the new orderedcoll compliance class in the DAV header.
When responding to an OPTIONS request, only a collection or a null
resource can include orderedcoll in the value of the DAV header. By
including orderedcoll, the resource indicates that its internal member
URIs can be ordered. It implies nothing about whether any collections
identified by its internal member URIs can be ordered.
Furthermore, RFC 3253 introduces the live properties
DAV:supported-method-set (section 3.1.3) and DAV:supported-live-property-set
(section 3.1.4). Servers MUST support these properties as defined in RFC 3253.
>> Request:
OPTIONS /somecollection/ HTTP/1.1
HOST: somehost.org
>> Response:
HTTP/1.1 200 OK
Date: Tue, 20 Jan 1998 20:52:29 GMT
Connection: close
Accept-Ranges: none
Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE,
MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, ORDERPATCH
DAV: 1, 2, orderedcoll
The DAV header in the response indicates that the resource
/somecollection/ is level 1 and level 2 compliant, as defined in
. In addition, /somecollection/ supports ordering. The Allow
header indicates that ORDERPATCH requests can be submitted to
/somecollection/.
>> Request:PROPFIND /somecollection HTTP/1.1
Host: somehost.org
Depth: 0
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
<?xml version="1.0" encoding="UTF-8" ?>
<propfind xmlns="DAV:">
<prop>
<supported-live-property-set/>
<supported-method-set/>
</prop>
</propfind>
>> Response:HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
<?xml version="1.0" encoding="utf-8" ?>
<multistatus xmlns="DAV:">
<response>
<href>http://somehost.org/somecollection</href>
<propstat>
<prop>
<supported-live-property-set>
<supported-live-property>
<prop><orderingtype/></prop>
</supported-live-property>
... other live properties omitted for brevity ...
</supported-live-property-set>
<supported-method-set>
<supported-method name="COPY" />
<supported-method name="DELETE" />
<supported-method name="GET" />
<supported-method name="HEAD" />
<supported-method name="LOCK" />
<supported-method name="MKCOL" />
<supported-method name="MOVE" />
<supported-method name="OPTIONS" />
<supported-method name="ORDERPATCH" />
<supported-method name="POST" />
<supported-method name="PROPFIND" />
<supported-method name="PROPPATCH" />
<supported-method name="PUT" />
<supported-method name="TRACE" />
<supported-method name="UNLOCK" />
</supported-method-set>
</prop>
<status>HTTP/1.1 200 OK</status>
</propstat>
</response>
</multistatus>
Note that actual responses MUST contain a complete list of supported live
properties.
This section is provided to make WebDAV applications aware of the
security implications of this protocol.
All of the security considerations of HTTP/1.1 and the WebDAV
Distributed Authoring Protocol specification also apply to this protocol
specification. In addition, ordered collections introduce a new
security concern. This issue is detailed here.
There may be some risk of denial of service at sites that are advertised
in the DAV:orderingtype property of collections. However, it is
anticipated that widely-deployed applications will use hard-coded values
for frequently-used ordering semantics rather than looking up the
semantics at the location specified by DAV:orderingtype. This risk will
be further reduced if clients observe the recommendation of
that they not send requests to the URI in DAV:orderingtype.
This specification follows the practices of in encoding all
human-readable content using and in the treatment of names.
Consequently, this specification complies with the IETF Character Set
Policy .
WebDAV applications MUST support the character set tagging, character
set encoding, and the language tagging functionality of the XML
specification. This constraint ensures that the human-readable content
of this specification complies with .
As in , names in this specification fall into three categories:
names of protocol elements such as methods and headers, names of XML
elements, and names of properties. Naming of protocol elements follows
the precedent of HTTP, using English names encoded in USASCII for
methods and headers. The names of XML elements used in this
specification are English names encoded in UTF-8.
For error reporting, follows the convention of HTTP/1.1 status
codes, including with each status code a short, English description of
the code (e.g., 423 Locked). Internationalized applications will ignore
this message, and display an appropriate message in the user's language
and character set.
This specification introduces no new strings that are displayed to users
as part of normal, error-free operation of the protocol.
For rationales for these decisions and advice for application
implementors, see .
This document uses the namespaces defined by for properties and
XML elements. All other IANA considerations mentioned in also
apply to this document.
To be supplied by the RFC Editor.
To be supplied by the RFC Editor.
This draft has benefited from thoughtful discussion by Jim Amsden, Steve
Carter, Tyson Chihaya, Geoff Clemm, Ken Coar, Ellis Cohen, Bruce Cragun, Spencer
Dawkins, Mark Day, Rajiv Dulepet, David Durand, Roy Fielding, Yaron
Goland, Fred Hitt, Alex Hopmann, Marcus Jager, Chris Kaler, Manoj
Kasichainula, Rohit Khare, Daniel LaLiberte, Lisa Lippert, Steve Martin,
Larry Masinter, Jeff McAffer, Surendra Koduru Reddy, Max Rible, Sam
Ruby, Bradley Sergeant, Nick Shelness, John Stracke, John Tigue, John
Turner, Kevin Wiggen, and others.
IETF Policy on Character Sets and LanguagesUNINETTP.O.Box 6883 ElgeseterN-7002 TRONDHEIMNORWAY+47 73 59 70 94Harald.T.Alvestrand@uninett.no
Applications
Internet Engineering Task Forcecharacter encodingUniform Resource Identifiers (URI): Generic SyntaxWorld Wide Web ConsortiumMIT Laboratory for Computer Science, NE43-356545 Technology SquareCambridgeMA02139+1(617)258-8682timbl@w3.orgDepartment of Information and Computer ScienceUniversity of California, IrvineIrvineCA92697-3425+1(949)824-1715fielding@ics.uci.eduXerox PARC3333 Coyote Hill RoadPalo AltoCA94034+1(415)812-4333masinter@parc.xerox.com
Applications
uniform resourceURI
A Uniform Resource Identifier (URI) is a compact string of characters
for identifying an abstract or physical resource. This document
defines the generic syntax of URI, including both absolute and
relative forms, and guidelines for their use; it revises and replaces
the generic definitions in RFC 1738 and RFC 1808.
This document defines a grammar that is a superset of all valid URI,
such that an implementation can parse the common components of a URI
reference without knowing the scheme-specific requirements of every
possible identifier type. This document does not define a generative
grammar for URI; that task will be performed by the individual
specifications of each URI scheme.
This paper describes a "superset" of operations that can be applied
to URI. It consists of both a grammar and a description of basic
functionality for URI. To understand what is a valid URI, both the
grammar and the associated description have to be studied. Some of
the functionality described is not applicable to all URI schemes, and
some operations are only possible when certain media types are
retrieved using the URI, regardless of the scheme used.
Key words for use in RFCs to Indicate Requirement LevelsHarvard University1350 Mass. Ave.CambridgeMA 02138- +1 617 495 3864-
General
keyword
In many standards track documents several words are used to signify
the requirements in the specification. These words are often
capitalized. This document defines these words as they should be
interpreted in IETF documents. Authors who follow these guidelines
should incorporate this phrase near the beginning of their document:
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
RFC 2119.
Note that the force of these words is modified by the requirement
level of the document in which they are used.
Extensible Markup Language (XML) 1.0World Wide Web ConsortiumMIT Laboratory for Computer Science545 Technology SquareCambridgeMA02139US+ 1 617 253 2613+ 1 617 258 5999timbl@w3.orghttp://www.w3c.orgHypertext Transfer Protocol -- HTTP/1.1University of California, Irvinefielding@ics.uci.eduW3Cjg@w3.orgCompaq Computer Corporationmogul@wrl.dec.comMIT Laboratory for Computer Sciencefrystyk@w3.orgXerox Corporationmasinter@parc.xerox.comMicrosoft Corporationpaulle@microsoft.comW3Ctimbl@w3.orgHTTP Extensions for Distributed Authoring -- WEBDAVMicrosoft Corporationyarong@microsoft.comDept. Of Information and Computer Science, University of California, Irvineejw@ics.uci.eduNetscapeasad@netscape.comNovellsrcarter@novell.comNovelldcjensen@novell.comVersioning Extensions to WebDAVRational Softwaregeoffrey.clemm@rational.comIBMjamsden@us.ibm.comIBMtim_ellison@uk.ibm.comMicrosoftckaler@microsoft.comUC Santa Cruz, Dept. of Computer Scienceejw@cse.ucsc.edu
<!--============= XML Elements from Section 11 ================-->
<!ELEMENT unordered EMPTY >
<!ELEMENT custom EMPTY >
<!ELEMENT order (orderingtype?, ordermember*) >
<!ELEMENT ordermember (href, position) >
<!ELEMENT position (first | last | before | after)>
<!ELEMENT first EMPTY >
<!ELEMENT last EMPTY >
<!ELEMENT before segment >
<!ELEMENT after segment >
<!ELEMENT segment (#PCDATA)>
<!--============= Property Elements from Section 10 =============-->
<!ELEMENT orderingtype (unordered | custom | href) >
Updated contact information for all previous authors.
Specify charset when using text/xml media type.
Made sure artwork fits into 72 columns.
Removed "Public" header from OPTIONS example.
Added Julian Reschke to list of authors.
Fixed broken XML in PROPFIND example and added DAV:orderingtype to list
of requested properties.
Added support for DAV:supported-live-property-set and DAV:supported-method-set
as mandatory features.
Updated contact information for all previous authors.
Specify charset when using text/xml media type.
Made sure artwork fits into 72 columns.
Removed "Public" header from OPTIONS example.
Added Julian Reschke to list of authors.
Fixed broken XML in PROPFIND example and added DAV:orderingtype to list
of requested properties.
Added support for DAV:supported-live-property-set and DAV:supported-method-set
as mandatory features.
Updated change log to refer to expired draft version as "December 1999" version.
Started rewrite marshalling in RFC3253-style and added precondition and postcondition
definitions.
On his request, removed Geoff Clemm's name from the author list (moved to
Acknowledgments).
Renamed "References" to "Normative References".
Removed reference to "MKREF" method.