draft-reschke-webdav-search-18
TOC
Network Working Group
J. Reschke, Ed.
Internet-Draft
greenbytes
Intended status: Standards Track
S. Reddy
Expires: March 3, 2009
Mitrix
J. Davis
A. Babich
IBM
August 30, 2008
Web Distributed Authoring and Versioning (WebDAV) SEARCH
draft-reschke-webdav-search-18
Status of this Memo
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Abstract
This document specifies a set of methods, headers and properties
composing WebDAV SEARCH, an application of the HTTP/1.1 protocol to efficiently search for DAV
resources based upon a set of client-supplied criteria.
Editorial Note (To be removed by RFC Editor before publication)
Please send comments to the Distributed Authoring and Versioning (WebDAV)
DASL mailing list at
mailto:www-webdav-dasl@w3.org
which may be joined by sending a message with subject "subscribe" to
mailto:www-webdav-dasl-request@w3.org
Discussions of the WebDAV DASL mailing list are archived at
An issues list and XML and HTML versions of this draft are available from
Table of Contents
1.
Introduction
1.1.
DASL
1.2.
Relationship to DAV
1.3.
1.4.
Notational Conventions
1.5.
Note on Usage of 'DAV:' XML Namespace
1.6.
An Overview of DASL at Work
2.
The SEARCH Method
2.1.
Overview
2.2.
The Request
2.2.1.
The Request-URI
2.2.2.
The Request Body
2.3.
The Successful 207 (Multistatus) Response
2.3.1.
Result Set Truncation
2.3.2.
Extending the PROPFIND Response
2.3.3.
Example: A Simple Request and Response
2.3.4.
Example: Result Set Truncation
2.4.
Unsuccessful Responses
2.4.1.
Example of an Invalid Scope
3.
Discovery of Supported Query Grammars
3.1.
The OPTIONS Method
3.2.
The DASL Response Header
3.3.
DAV:supported-query-grammar-set (protected)
3.4.
Example: Grammar Discovery
4.
Query Schema Discovery: QSD
4.1.
Additional SEARCH Semantics
4.1.1.
Example of Query Schema Discovery
5.
The DAV:basicsearch Grammar
5.1.
Introduction
5.2.
The DAV:basicsearch DTD
5.2.1.
Example Query
5.3.
DAV:select
5.4.
DAV:from
5.4.1.
Relationship to the Request-URI
5.4.2.
Scope
5.5.
DAV:where
5.5.1.
Use of Three-Valued Logic in Queries
5.5.2.
Handling Optional Operators
5.5.3.
Treatment of NULL Values
5.5.4.
Treatment of Properties with mixed/element Content
5.5.5.
Example: Testing for Equality
5.5.6.
Example: Relative Comparisons
5.6.
DAV:orderby
5.6.1.
Example of Sorting
5.7.
Boolean Operators: DAV:and, DAV:or, and DAV:not
5.8.
DAV:eq
5.9.
DAV:lt, DAV:lte, DAV:gt, DAV:gte
5.10.
DAV:literal
5.11.
DAV:typed-literal (optional)
5.11.1.
Example for Typed Numerical Comparison
5.12.
Support for Matching xml:lang Attributes on Properties
5.12.1.
DAV:language-defined (optional)
5.12.2.
DAV:language-matches (optional)
5.12.3.
Example of Language-Aware Matching
5.13.
DAV:is-collection
5.13.1.
Example of DAV:is-collection
5.14.
DAV:is-defined
5.15.
DAV:like
5.15.1.
Syntax for the Literal Pattern
5.15.2.
Example of DAV:like
5.16.
DAV:contains
5.16.1.
Result Scoring (DAV:score Element)
5.16.2.
Ordering by Score
5.16.3.
Examples
5.17.
Limiting the Result Set
5.17.1.
Relationship to Result Ordering
5.18.
The 'caseless' XML Attribute
5.19.
Query Schema for DAV:basicsearch
5.19.1.
DTD for DAV:basicsearch QSD
5.19.2.
DAV:propdesc Element
5.19.3.
The DAV:datatype Property Description
5.19.4.
The DAV:searchable Property Description
5.19.5.
The DAV:selectable Property Description
5.19.6.
The DAV:sortable Property Description
5.19.7.
The DAV:caseless Property Description
5.19.8.
The DAV:operators XML Element
5.19.9.
Example of Query Schema for DAV:basicsearch
6.
Internationalization Considerations
7.
Security Considerations
7.1.
Implications of XML External Entities
8.
Scalability
9.
IANA Considerations
9.1.
HTTP Headers
9.1.1.
DASL
10.
Contributors
11.
Acknowledgements
12.
References
12.1.
Normative References
12.2.
Informative References
Appendix A.
Three-Valued Logic in DAV:basicsearch
Appendix B.
Candidates for Future Protocol Extensions
B.1.
Collation Support
B.2.
Count
B.3.
Diagnostics for Unsupported Queries
B.4.
Language Matching
B.5.
Matching Media Types
B.6.
Query by Name
B.7.
Result Paging
B.8.
Search Scope Discovery
Appendix C.
Change Log (to be removed by RFC Editor before publication)
C.1.
From draft-davis-dasl-protocol-xxx
C.2.
since start of draft-reschke-webdav-search
C.3.
since draft-reschke-webdav-search-00
C.4.
since draft-reschke-webdav-search-01
C.5.
since draft-reschke-webdav-search-02
C.6.
since draft-reschke-webdav-search-03
C.7.
since draft-reschke-webdav-search-04
C.8.
since draft-reschke-webdav-search-05
C.9.
since draft-reschke-webdav-search-06
C.10.
since draft-reschke-webdav-search-07
C.11.
since draft-reschke-webdav-search-08
C.12.
since draft-reschke-webdav-search-09
C.13.
since draft-reschke-webdav-search-10
C.14.
since draft-reschke-webdav-search-11
C.15.
since draft-reschke-webdav-search-12
C.16.
since draft-reschke-webdav-search-13
C.17.
since draft-reschke-webdav-search-14
C.18.
since draft-reschke-webdav-search-15
C.19.
since draft-reschke-webdav-search-16
C.20.
since draft-reschke-webdav-search-17
Appendix D.
Resolved issues (to be removed by RFC Editor before publication)
D.1.
safeness
D.2.
ordering-vs-limiting
Appendix E.
Open issues (to be removed by RFC Editor prior to publication)
E.1.
edit
Index
Authors' Addresses
Intellectual Property and Copyright Statements
TOC
1.
Introduction
TOC
1.1.
DASL
This document defines Web Distributed Authoring and Versioning (WebDAV) SEARCH, an application
of HTTP/1.1 forming a lightweight search protocol to transport queries
and result sets that allows clients to make use of server-side search facilities.
It is based on the expired internet draft for DAV Searching & Locating
[DASL]
Reddy, S., Lowry, D., Reddy, S., Henderson, R., Davis, J., and A. Babich, “DAV Searching & Locating,” July 1999.
[DASLREQ]
Davis, J., Reddy, S., and J. Slein, “Requirements for DAV Searching and Locating,” February 1999.
describes the motivation for DASL.
In this specification, the terms "WebDAV SEARCH" and "DASL" are used interchangeably.
DASL minimizes the complexity of clients so as to facilitate widespread
deployment of applications capable of utilizing the DASL search mechanisms.
DASL consists of:
the SEARCH method and the request/response formats defined for it (
Section 2
The SEARCH Method
),
feature discovery through the "DASL" response header and
the optional DAV:supported-grammar-set property (
Section 3
Discovery of Supported Query Grammars
),
optional grammar schema discovery (
Section 4
Query Schema Discovery: QSD
) and
one mandatory grammar: DAV:basicsearch (
Section 5
The DAV:basicsearch Grammar
).
TOC
1.2.
Relationship to DAV
DASL relies on the resource and property model defined by
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
DASL does not alter this model. Instead, DASL allows clients to access DAV-modeled
resources through server-side search.
TOC
1.3.
This document uses the terms defined in
[RFC2616]
Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1,” June 1999.
, in
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
, in
[RFC3253]
Clemm, G., Amsden, J., Ellison, T., Kaler, C., and J. Whitehead, “Versioning Extensions to WebDAV,” March 2002.
and in this section.
Criteria
An expression against which each resource in the search scope is evaluated.
Query
A query is a combination of a search scope, search criteria, result record
definition, sort specification, and a search modifier.
Query Grammar
A set of definitions of XML elements, attributes, and constraints on their
relations and values that defines a set of queries and the intended semantics.
Query Schema
A listing, for any given grammar and scope, of the properties and operators
that may be used in a query with that grammar and scope.
Result
A result is a result set, optionally augmented with other information describing the search as a whole.
Result Record
A description of a resource. A result record is a set of properties, and possibly other descriptive information.
Result Record Definition
A specification of the set of properties to be returned in the result record.
Result Set
A set of records, one for each resource for which the search criteria evaluated to True.
Scope
A set of resources to be searched.
Search Arbiter
A resource that supports the SEARCH method.
Search Modifier
An instruction that governs the execution of the query but is not part of
the search scope, result record definition, the search criteria, or the sort
specification. An example of a search modifier is one that controls how
much time the server can spend on the query before giving a response.
Sort Specification
A specification of an ordering on the result records in the result set.
TOC
1.4.
Notational Conventions
This specification uses the Augmented Backus-Naur Form (ABNF) notation of
[RFC5234]
Crocker, D., Ed. and P. Overell, “Augmented BNF for Syntax Specifications: ABNF,” January 2008.
unless explicitly stated otherwise.
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]
Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.
This document uses XML DTD fragments
[XML]
Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and F. Yergeau, “Extensible Markup Language (XML) 1.0 (Fourth Edition),” August 2006.
, Section 3.2) as a purely notational convention. WebDAV
request and response bodies can not be validated by a DTD due to the specific
extensibility rules defined in Section 17 of
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
and
due to the fact that all XML elements defined by this specification use the
XML namespace name "DAV:". In particular:
element names use the "DAV:" namespace,
element ordering is irrelevant unless explicitly stated,
extension elements (elements not already defined as valid child
elements) may be added anywhere, except when explicitly stated otherwise,
extension attributes (attributes not already defined as valid for this
element) may be added anywhere, except when explicitly stated otherwise.
When an XML element type in the "DAV:" namespace is referenced in this document
outside of the context of an XML fragment, the string "DAV:" will be prefixed to
the element type.
Similarly, when an XML element type in the namespace "http://www.w3.org/2001/XMLSchema"
is referenced in this document outside of the context of an XML fragment, the
string "xs:" will be prefixed to the element type.
This document inherits, and sometimes extends, DTD productions from Section 14 of
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
TOC
1.5.
Note on Usage of 'DAV:' XML Namespace
This specification defines elements, properties and condition names in the
XML namespace "DAV:". In general, only specifications authored by IETF
working groups are supposed to do this. In this case an exception was made,
because WebDAV SEARCH started its life in the IETF DASL working group
, and at the time the working
group closed down there was already significant deployment of this specification.
TOC
1.6.
An Overview of DASL at Work
One can express the basic usage of DASL in the following steps:
The client constructs a query using the DAV:basicsearch grammar.
The client invokes the SEARCH method on a resource that will perform the
search (the search arbiter) and includes a text/xml or application/xml request entity that
contains the query.
The search arbiter performs the query.
The search arbiter sends the results of the query back to the client in
the response. The server MUST send an entity
that matches the
WebDAV multistatus format (
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
, Section 13).
TOC
2.
The SEARCH Method
TOC
2.1.
Overview
The client invokes the SEARCH method to initiate a server-side search.
The body of the request defines the query. The server MUST emit
an entity matching the WebDAV multistatus format
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
, Section 13).
The SEARCH method plays the role of transport mechanism for the query
and the result set. It does not define the semantics of the query. The
type of the query defines the semantics.
SEARCH is a safe method; it does not have any significance other than
executing a query and returning a query result (see
[RFC2616]
Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1,” June 1999.
, Section 9.1.1).
TOC
2.2.
The Request
The client invokes the SEARCH method on the resource named by the Request-URI.
TOC
2.2.1.
The Request-URI
The Request-URI identifies the search arbiter.
Any HTTP resource may function as search arbiter. It is not a new type of
resource (in the sense of DAV:resourcetype as defined in
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
, Section 15.9),
nor does it have to be a WebDAV-compliant resource.
The SEARCH method defines no relationship between the arbiter and the
scope of the search, rather the particular query grammar used in the query
defines the relationship. For example, a query grammar may force
the Request-URI to correspond exactly to the search scope.
TOC
2.2.2.
The Request Body
The server MUST process a text/xml or application/xml request body, and
MAY process request bodies in other formats. See
[RFC3023]
Makoto, M., St.Laurent, S., and D. Kohn, “XML Media Types,” January 2001.
for guidance
on packaging XML in requests.
Marshalling:
If a request body with content type text/xml or application/xml is included,
it MUST be either a DAV:searchrequest or a DAV:query-schema-discovery XML
element. Its single child element identifies the query grammar.
For DAV:searchrequest, the definition of search criteria, the result record,
and any other details needed to perform the search depend on the individual
search grammar.
For DAV:query-schema-discovery, the semantics is defined in
Section 4
Query Schema Discovery: QSD
Preconditions:
(DAV:search-grammar-discovery-supported): when an XML request body is present
and has a DAV:query-schema-discovery document element, the server MUST
support the query schema discovery mechanism described in
Section 4
Query Schema Discovery: QSD
(DAV:search-grammar-supported): when an XML request body is present,
the search grammar identified by the document element's child element
must be a supported search grammar.
(DAV:search-multiple-scope-supported): if the SEARCH request specified
multiple scopes, the server MUST support this optional feature.
(DAV:search-scope-valid): the supplied search scope must be valid. There
can be various reasons for a search scope to be invalid, including
unsupported URI schemes and communication problems. Servers MAY add
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
compliant DAV:response elements as content to the
condition element indicating the precise reason for the failure.
TOC
2.3.
The Successful 207 (Multistatus) Response
If the server returns 207 (Multistatus), then the search proceeded successfully
and the response MUST
use the WebDAV multistatus format (
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
, Section 13).
The results of this method SHOULD NOT be cached.
There MUST be one DAV:response for each resource that matched
the search criteria. For each such response, the DAV:href element
contains the URI of the resource, and the response MUST include a DAV:propstat
element.
Note: the WebDAV multistatus format requires at least one
DAV:response child element. This specification relaxes that restriction
so that empty results can be represented.
Note that for each matching resource found there may be multiple URIs
within the search scope mapped to it. In this case, a server SHOULD report
only one of these URIs. Clients can use the live property DAV:resource-id defined
in Section 3.1 of
[draft‑ietf‑webdav‑bind]
Clemm, G., Crawford, J., Reschke, J., Ed., and J. Whitehead, “Binding Extensions to Web Distributed Authoring and Versioning (WebDAV),” November 2007.
to identify possible duplicates.
TOC
2.3.1.
Result Set Truncation
A server MAY limit the number of resources in a reply, for example to limit
the amount of resources expended in processing a query. If it does so,
the reply MUST use status code 207, return a DAV:multistatus response
body and indicate a status of 507 (Insufficient Storage) for the search
arbiter URI. It SHOULD include the partial results.
When a result set is truncated, there may be many more resources that
satisfy the search criteria but that were not examined.
If partial results are included and the client requested an ordered
result set in the original request, then any partial results that are returned
MUST be ordered as the client directed.
Note that the partial results returned MAY be any subset of the result
set that would have satisfied the original query.
TOC
2.3.2.
Extending the PROPFIND Response
A response MAY include more information than PROPFIND defines so long as
the extra information does not invalidate the PROPFIND response. Query
grammars SHOULD define how the response matches the PROPFIND response.
TOC
2.3.3.
Example: A Simple Request and Response
This example demonstrates the request and response framework. The following
XML document shows a simple (hypothetical) natural language query.
The name of the query element is natural-language-query in the XML namespace
"http://example.com/foo". The actual query is "Find the
locations of good Thai restaurants in Los Angeles". For this hypothetical
query, the arbiter returns two properties for each selected resource.
>> Request:
SEARCH / HTTP/1.1
Host: example.org
Content-Type: application/xml; charset="utf-8"
Content-Length: 252
Find the locations of good Thai restaurants in Los Angeles
>> Response:
HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: 429
TOC
2.3.4.
Example: Result Set Truncation
In the example below, the server returns just two results, and then
indicates that the result is truncated by adding a DAV:response element
for the search arbiter resource with 507 (Insufficient Storage) status.
>> Request:
SEARCH / HTTP/1.1
Host: example.net
Content-Type: text/xml; charset="utf-8"
Content-Length: xxx
... the query goes here ...
>> Response:
HTTP/1.1 207 Multistatus
Content-Type: text/xml; charset="utf-8"
Content-Length: 640
Only first two matching records were returned
TOC
2.4.
Unsuccessful Responses
If a SEARCH request could not be executed or the attempt to execute it
resulted in an error, the server MUST indicate the failure with an
appropriate status code and SHOULD add a response body as defined in
[RFC3253]
Clemm, G., Amsden, J., Ellison, T., Kaler, C., and J. Whitehead, “Versioning Extensions to WebDAV,” March 2002.
, Section 1.6. Unless otherwise stated, condition
elements are empty, however specific condition elements MAY include
additional child elements that describe the error condition in more detail.
TOC
2.4.1.
Example of an Invalid Scope
In the example below, a request failed because the scope identifies a
HTTP resource that was not found.
>> Response:
HTTP/1.1 409 Conflict
Content-Type: text/xml; charset="utf-8"
Content-Length: 275
TOC
3.
Discovery of Supported Query Grammars
Servers MUST support discovery of the query grammars supported by a search
arbiter resource.
Clients can determine which query grammars are supported by an arbiter
by invoking OPTIONS on the search arbiter. If the resource supports SEARCH,
then the DASL response header will appear in the response. The DASL response
header lists the supported grammars.
Servers supporting the WebDAV extensions
[RFC3253]
Clemm, G., Amsden, J., Ellison, T., Kaler, C., and J. Whitehead, “Versioning Extensions to WebDAV,” March 2002.
and/or
[RFC3744]
Clemm, G., Reschke, J., Sedlar, E., and J. Whitehead, “Web Distributed Authoring and Versioning (WebDAV) Access Control Protocol,” May 2004.
MUST also
report SEARCH in the live property DAV:supported-method-set for all search arbiter resources and
support the live property DAV:supported-query-grammar-set as defined in
Section 3.3
DAV:supported-query-grammar-set (protected)
TOC
3.1.
The OPTIONS Method
The OPTIONS method allows the client to discover if a resource supports
the SEARCH method and to determine the list of search grammars supported
for that resource.
The client issues the OPTIONS method against a resource named by the
Request-URI. This is a normal invocation of OPTIONS as defined in Section 9.2 of
[RFC2616]
Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1,” June 1999.
If a resource supports the SEARCH method, then the server MUST list
SEARCH in the Allow header
defined in Section 14.7 of
[RFC2616]
Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1,” June 1999.
DASL servers MUST include the DASL header in the OPTIONS response. This
header identifies the search grammars supported by that resource.
TOC
3.2.
The DASL Response Header
DASLHeader = "DASL" ":" 1#Coded-URL
Coded-URL =
(This grammar uses the augmented BNF format defined in Section 2.1 of
[RFC2616]
Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1,” June 1999.
The DASL response header indicates server support for query grammars in
the OPTIONS method. The value is a
list of URIs that indicate the types of supported grammars.
Note that although the URIs can be used to identify each supported search
grammar, there is not necessarily a direct relationship between the URI and the
XML element name that can be used in XML based SEARCH requests (the element
name itself is identified by its namespace name (a URI reference) and
the element's local name).
Note: this header field value is defined as a comma-separated list
[RFC2616]
Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1,” June 1999.
, Section 4.2), thus grammar URIs can
appear in multiple header instances, separated by commas, or both.
For example:
DASL:
DASL:
TOC
3.3.
DAV:supported-query-grammar-set (protected)
This WebDAV property is required for any server supporting either
[RFC3253]
Clemm, G., Amsden, J., Ellison, T., Kaler, C., and J. Whitehead, “Versioning Extensions to WebDAV,” March 2002.
and/or
[RFC3744]
Clemm, G., Reschke, J., Sedlar, E., and J. Whitehead, “Web Distributed Authoring and Versioning (WebDAV) Access Control Protocol,” May 2004.
and
identifies the XML based query grammars that are supported by the search arbiter resource.
TOC
3.4.
Example: Grammar Discovery
This example shows that the server supports search on the /somefolder
resource with the query grammars: DAV:basicsearch, http://foobar.example/syntax1
and http://akuma.example/syntax2. Note that servers supporting WebDAV SEARCH MUST support
DAV:basicsearch.
>> Request:
OPTIONS /somefolder HTTP/1.1
Host: example.org
>> Response:
HTTP/1.1 200 OK
Allow: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, COPY, MOVE
Allow: MKCOL, PROPFIND, PROPPATCH, LOCK, UNLOCK, SEARCH
DASL:
DASL:
This example shows the equivalent taking advantage of a server's support for
DAV:supported-method-set and DAV:supported-query-grammar-set.
>> Request:
PROPFIND /somefolder HTTP/1.1
Host: example.org
Depth: 0
Content-Type: text/xml; charset="utf-8"
Content-Length: 165
>> Response:
HTTP/1.1 207 Multi-Status
Content-Type: text/xml; charset="utf-8"
Content-Length: 1349
Note that the query grammar element names marshalled as part of the
DAV:supported-query-grammar-set can be directly used as element names in
an XML based query.
TOC
4.
Query Schema Discovery: QSD
Servers MAY support the discovery of the schema for a query grammar.
The DASL response header and the DAV:supported-query-grammar-set property
provide means for clients to discover the
set of query grammars supported by a resource. This alone is not sufficient
information for a client to generate a query. For example, the DAV:basicsearch
grammar defines a set of queries consisting of a set of operators applied
to a set of properties and values, but the grammar itself does not specify
which properties may be used in the query. QSD for the DAV:basicsearch
grammar allows a client to discover the set of properties that are searchable,
selectable, and sortable. Moreover, although the DAV:basicsearch
grammar defines a minimal set of operators, it is possible that a resource
might support additional operators in a query. For example, a resource
might support an optional operator that can be used to express content-based
queries in a proprietary syntax. QSD allows a client to discover these
operators and their syntax. The set of discoverable quantities will differ
from grammar to grammar, but each grammar can define a means for a client
to discover what can be discovered.
In general, the schema for a given query grammar depends on both the
resource (the arbiter) and the scope. A given resource might have access
to one set of properties for one potential scope, and another set for a
different scope. For example, consider a server able to search two distinct
collections, one holding cooking recipes, the other design documents for
nuclear weapons. While both collections might support properties such as
author, title, and date, the first might also define properties such as
calories and preparation time, while the second defined properties such
as yield and applicable patents. Two distinct arbiters indexing the same
collection might also have access to different properties. For example,
the recipe collection mentioned above might also be indexed by a value-added
server that also stored the names of chefs who had tested the recipe. Note
also that the available query schema might also depend on other factors,
such as the identity of the principal conducting the search, but these
factors are not exposed in this protocol.
TOC
4.1.
Additional SEARCH Semantics
Each query grammar supported by DASL defines its own syntax for expressing
the possible query schema. A client retrieves the schema for a given query
grammar on an arbiter resource with a given scope by invoking the SEARCH
method on that arbiter with that grammar and scope and with a root element
of DAV:query-schema-discovery rather than DAV:searchrequest.
Marshalling:
The request body MUST be a DAV:query-schema-discovery element.
The response body takes the form of a DAV:multistatus element (
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
, Section 13),
where DAV:response is extended to hold the returned query grammar
inside a DAV:query-schema container element.
responsedescription?) >
The content of this container is an XML element whose name and syntax depend upon the grammar,
and whose value may (and likely will) vary depending upon the grammar,
arbiter, and scope.
TOC
4.1.1.
Example of Query Schema Discovery
In this example, the arbiter is recipes.example, the grammar is DAV:basicsearch,
the scope is also recipes.example.
>> Request:
SEARCH / HTTP/1.1
Host: recipes.example
Content-Type: application/xml; charset="utf-8"
Content-Length: 258
>> Response:
HTTP/1.1 207 Multistatus
Content-Type: application/xml; charset="utf-8"
Content-Length: xxx
The query schema for DAV:basicsearch is defined in
Section 5.19
Query Schema for DAV:basicsearch
TOC
5.
The DAV:basicsearch Grammar
TOC
5.1.
Introduction
DAV:basicsearch uses an extensible XML syntax that allows clients
to express search requests that are generally useful for WebDAV scenarios.
DASL-extended servers MUST accept this grammar, and MAY accept other grammars.
DAV:basicsearch has several components:
DAV:select provides the result record definition.
DAV:from defines the scope.
DAV:where defines the criteria.
DAV:orderby defines the sort order of the result set.
DAV:limit provides constraints on the query as a whole.
TOC
5.2.
The DAV:basicsearch DTD
language-defined | language-matches">
%string_ops; | %content_ops;">
TOC
5.2.1.
Example Query
This query retrieves the content length values for all resources located
under the server's "/container1/" URI namespace whose length exceeds 10000 sorted ascending by size.
TOC
5.3.
DAV:select
DAV:select defines the result record, which is a set of properties
and values. This document defines two possible values: DAV:allprop
and DAV:prop, both defined in Section 14 of
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
TOC
5.4.
DAV:from
DAV:from defines the query scope.
This contains one or more DAV:scope elements. Support for multiple scope
elements is optional, however servers MUST fail a request specifying
multiple DAV:scope elements if they can't support it (see
Section 2.2.2
The Request Body
precondition DAV:search-multiple-scope-supported).
The scope element contains mandatory DAV:href and DAV:depth elements.
DAV:href indicates the URI reference (
[RFC3986]
Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax,” January 2005.
, Section 4.1) to use as a scope.
When the scope is a collection, if DAV:depth is "0", the search
includes only the collection.
When it is "1", the search includes the collection and its immediate
children. When it is "infinity", it includes the collection and all its progeny.
When the scope is not a collection, the
depth is ignored and the search applies just to the resource itself.
If the server supports WebDAV Redirect Reference Resources (
[RFC4437]
Whitehead, J., Clemm, G., and J. Reschke, Ed., “Web Distributed Authoring and Versioning (WebDAV) Redirect Reference Resources,” March 2006.
and the search scope contains a redirect reference resource, then
it applies only to that resource, not to its target.
When the child element DAV:include-versions is present, the search scope
will include all versions (see
[RFC3253]
Clemm, G., Amsden, J., Ellison, T., Kaler, C., and J. Whitehead, “Versioning Extensions to WebDAV,” March 2002.
, Section 2.2.1) of all
version-controlled resources in scope. Servers that do support versioning
but do not support the DAV:include-versions feature MUST signal an
error if it is used in a query (see
Section 2.2.2
The Request Body
, precondition DAV:search-scope-valid).
TOC
5.4.1.
Relationship to the Request-URI
If the DAV:scope element is an URI (
[RFC3986]
Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax,” January 2005.
, Section 3), the scope is exactly
that URI.
If the DAV:scope element is a relative reference (
[RFC3986]
Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax,” January 2005.
, Section 4.2), the scope is taken
to be relative to the Request-URI.
TOC
5.4.2.
Scope
A Scope can be an arbitrary URI reference.
Servers, of course, may support only particular scopes. This may include
limitations for particular schemes such as "http:" or "ftp:" or certain
URI namespaces.
However, WebDAV compliant search arbiters minimally SHOULD support
scopes that match their own URI.
TOC
5.5.
DAV:where
The DAV:where element defines the search condition for inclusion of
resources in the result set. The value of this element is an XML element
that defines a search operator that evaluates to one of the Boolean truth
values TRUE, FALSE, or UNKNOWN. The search operator contained by DAV:where
may itself contain and evaluate additional search operators as operands,
which in turn may contain and evaluate additional search operators as operands,
etc. recursively.
TOC
5.5.1.
Use of Three-Valued Logic in Queries
Each operator defined for use in the where clause that returns a Boolean
value MUST evaluate to TRUE, FALSE, or UNKNOWN. The resource under scan
is included as a member of the result set if and only if the search condition
evaluates to TRUE.
Consult
Appendix A
Three-Valued Logic in DAV:basicsearch
for details on the application of three-valued logic
in query expressions.
TOC
5.5.2.
Handling Optional Operators
If a query contains an operator that is not supported by the server, then
the server MUST respond with a 422 (Unprocessable Entity) status code.
TOC
5.5.3.
Treatment of NULL Values
If a PROPFIND for a property value would yield a
non-2xx (see
[RFC2616]
Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1,” June 1999.
, Section 10.2)
response for that property, then that property is considered NULL.
NULL values are "less than" all other values in comparisons.
Empty strings (zero length strings) are not NULL values. An empty string
is "less than" a string with length greater than zero.
The DAV:is-defined operator is defined to test if the value
of a property is not NULL.
TOC
5.5.4.
Treatment of Properties with mixed/element Content
Comparisons of properties that do not have simple types (text-only content) is
out-of-scope for the standard operators defined for DAV:basicsearch and therefore is defined
to be UNKNOWN (as per
Appendix A
Three-Valued Logic in DAV:basicsearch
).
For querying the DAV:resourcetype property, see
Section 5.13
DAV:is-collection
TOC
5.5.5.
Example: Testing for Equality
The example shows a single operator (DAV:eq) applied in the criteria.
TOC
5.5.6.
Example: Relative Comparisons
The example shows a more complex operation involving several operators
(DAV:and, DAV:eq, DAV:gt) applied in the criteria.
This DAV:where expression matches those resources of type "image/gif"
over 4K in size.
TOC
5.6.
DAV:orderby
The DAV:orderby element specifies the ordering of the result set. It contains
one or more DAV:order elements, each of which specifies a comparison between
two items in the result set. Informally, a comparison specifies a test that
determines whether one resource appears before another in the result set.
Comparisons are applied in the order they occur in the DAV:orderby element,
earlier comparisons being more significant.
The comparisons defined here use only a single property from each resource,
compared using the same ordering as the DAV:lt operator
(ascending
) or DAV:gt operator
(descending
).
If neither direction is specified, the default is DAV:ascending.
In the context of the DAV:orderby element, null values are
considered to collate before any actual (i.e., non null) value, including
strings of zero length (this is compatible with
[SQL99]
Milton, J., “Database Language SQL Part 2: Foundation (SQL/Foundation),” July 1999.
).
The "caseless" attribute may be used to indicate case-sensitivity
for comparisons (
Section 5.18
The 'caseless' XML Attribute
).
TOC
5.6.1.
Example of Sorting
This sort orders first by last name of the author, and then by size, in
descending order, so that for each author, the largest works appear first.
TOC
5.7.
Boolean Operators: DAV:and, DAV:or, and DAV:not
The DAV:and operator performs a logical AND operation on the expressions
it contains.
The DAV:or operator performs a logical OR operation on the values it contains.
The DAV:not operator performs a logical NOT operation on the
values it contains.
TOC
5.8.
DAV:eq
The DAV:eq operator provides simple equality matching on property values.
The "caseless" attribute may be used with this element (
Section 5.18
The 'caseless' XML Attribute
).
TOC
5.9.
DAV:lt, DAV:lte, DAV:gt, DAV:gte
The DAV:lt, DAV:lte, DAV:gt, and DAV:gte
operators provide comparisons on property values, using less-than, less-than
or equal, greater-than, and greater-than or equal respectively. The "caseless"
attribute may be used with these elements (
Section 5.18
The 'caseless' XML Attribute
).
TOC
5.10.
DAV:literal
DAV:literal allows literal values to be placed in an expression.
White space in literal values is significant in comparisons. For consistency
with
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
, clients SHOULD NOT specify the attribute "xml:space"
(Section 2.10 of
[XML]
Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and F. Yergeau, “Extensible Markup Language (XML) 1.0 (Fourth Edition),” August 2006.
) to override this behavior.
In comparisons, the contents of DAV:literal SHOULD be treated as string, with
the following exceptions:
when operand for a comparison with a DAV:getcontentlength property,
it SHOULD be treated as an unsigned integer value (the behavior for values not in this format
is undefined),
when operand for a comparison with a DAV:creationdate or DAV:getlastmodified property,
it SHOULD be treated as a date value in the ISO-8601 subset defined for
the DAV:creationdate property (see
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
, Section 15.1;
the behavior of values not in this format is undefined),
when operand for a comparison with a property for which the type is known and when compatible with that type,
it MAY be treated according to this type.
TOC
5.11.
DAV:typed-literal (optional)
There are situations in which a client may want to force a comparison not to
be string-based (as defined for DAV:literal). In these cases, a typed
comparison can be enforced by using DAV:typed-literal instead.
The data type is specified using the xsi:type attribute defined in
[XS1]
Thompson, H., Beech, D., Maloney, M., Mendelsohn, N., and World Wide Web Consortium, “XML Schema Part 1: Structures,” October 2004.
, Section 2.6.1. If the type is not specified, it
defaults to "xs:string".
A server MUST reject a request with an unknown type with a status of 422 (Unprocessable Entity).
It SHOULD reject a request if the value provided in DAV:typed-literal can not be cast to the specified type.
The comparison evaluates to UNKNOWN if the property value can not be
cast to the specified datatype (see
[XPATHFUNC]
Malhotra, A., Melton, J., and N. Walsh, “XQuery 1.0 and XPath 2.0 Functions and Operators,” January 2007.
, Section 17).
TOC
5.11.1.
Example for Typed Numerical Comparison
Consider a set of resources with the dead property "edits" in the namespace
"http://ns.example.org":
URI
property value
/a
"-1"
/b
"01"
/c
"3"
/d
"test"
/e
(undefined)
The expression
xmlns:xs="http://www.w3.org/2001/XMLSchema">
will evaluate to TRUE for the resources "/a" and "/b" (their property values
can be parsed as type xs:integer, and the numerical comparison evaluates to
true), to FALSE for "/c" (property value is compatible, but numerical comparison
evaluates to false) and UNKNOWN for "/d" and "/e" (the property either is
undefined, or its value can not be parsed as xs:integer).
TOC
5.12.
Support for Matching xml:lang Attributes on Properties
The following two optional operators can be used to express conditions
on the language of a property value (as expressed using the xml:lang
attribute).
TOC
5.12.1.
DAV:language-defined (optional)
This operator evaluates to TRUE if the language for the value of
the given property is known, FALSE if it isn't and UNKNOWN if the property itself
is not defined.
TOC
5.12.2.
DAV:language-matches (optional)
This operator evaluates to TRUE if the language for the value of the
given property is known and matches the language name given in the
if the property itself is not defined.
Languages are considered to match if they are the same, or if the
language of the property value is a sublanguage of the language
specified in the
[XPATH]
Clark, J. and S. DeRose, “XML Path Language (XPath) Version 1.0,” November 1999.
, Section 4.3,
"lang function").
TOC
5.12.3.
Example of Language-Aware Matching
The expression below will evaluate to TRUE if the property "foobar" exists
and its language is either unknown, English or a sublanguage of English.
TOC
5.13.
DAV:is-collection
The DAV:is-collection operator allows clients to determine whether a resource is
a collection (that is, whether its DAV:resourcetype element contains the
element DAV:collection).
Rationale: This operator is provided in lieu of defining generic
structure queries, which would suffice for this and for many more powerful
queries, but seems inappropriate to standardize at this time.
TOC
5.13.1.
Example of DAV:is-collection
This example shows a search criterion that picks out all and only the resources
in the scope that are collections.
TOC
5.14.
DAV:is-defined
The DAV:is-defined operator allows clients to determine whether
a property is defined on a resource. The meaning of "defined on a resource"
is found in
Section 5.5.3
Treatment of NULL Values
Example:
TOC
5.15.
DAV:like
The DAV:like is an optional operator intended to give simple wildcard-based
pattern matching ability to clients.
The operator takes two arguments.
The first argument is a DAV:prop element identifying a single
property to evaluate.
The second argument is a DAV:literal element that gives the
pattern matching string.
TOC
5.15.1.
Syntax for the Literal Pattern
pattern
= [
wildcard
0*
text
wildcard
] )
wildcard
exactlyone
zeroormore
text
1*
character
escapeseq
exactlyone
= "
zeroormore
= "
escapechar
= "
escapeseq
escapechar
exactlyone
zeroormore
escapechar
; character: see [XML], Section 2.2, minus wildcard / escapechar
character
HTAB
LF
CR
; whitespace
character
=/
%x20-24
%x26-5B
%x5D-5E
%x60-D7FF
character
=/
%xE000-FFFD
%x10000-10FFFF
(Note that the ABNF above is defined in terms of Unicode code points (
[UNICODE5]
The Unicode Consortium, “The Unicode Standard - Version 5.0,” November 2006.
);
when an query is transmitted as XML document WebDAV, these characters are
typically encoded in UTF-8 or UTF-16.)
The value for the literal is composed of wildcards separated by segments
of text. Wildcards may begin or end the literal.
The "_" wildcard matches exactly one character.
The "%" wildcard matches zero or more characters
The "\" character is an escape sequence so that the literal can include
"_" and "%". To include the "\" character in the pattern, the escape sequence
"\\" is used.
TOC
5.15.2.
Example of DAV:like
This example shows how a client might use DAV:like to identify
those resources whose content type was a subtype of image.
TOC
5.16.
DAV:contains
The DAV:contains operator is an optional operator that provides
content-based search capability. This operator implicitly searches against
the text content of a resource, not against content of properties. The
DAV:contains operator is intentionally not overly constrained, in order to allow the
server to do the best job it can in performing the search.
The DAV:contains operator evaluates to a Boolean value. It
evaluates to TRUE if the content of the resource satisfies the search.
Otherwise, it evaluates to FALSE.
Within the DAV:contains XML element, the client provides a
phrase: a single word or whitespace delimited sequence of words. Servers
MAY ignore punctuation in a phrase. Case-sensitivity is at the
discretion of the server implementation.
The following non-exhaustive list enumerate things that may or may not be done
as part of the search:
Phonetic
methods such as "soundex" may or may not be used. Word stemming may or
may not be performed. Thesaurus expansion of words may or may not be done.
Right or left truncation may or may not be performed. The search may be
case insensitive or case sensitive. The word or words may or may not be
interpreted as names. Multiple words may or may not be required to be adjacent
or "near" each other. Multiple words may or may not be required to occur
in the same order. Multiple words may or may not be treated as a phrase.
The search may or may not be interpreted as a request to find documents
"similar" to the string operand.
Character canonicalization such as that done by the Unicode collation
algorithm may or may not be applied.
TOC
5.16.1.
Result Scoring (DAV:score Element)
Servers SHOULD indicate scores for the DAV:contains condition by adding a
DAV:score XML element to the DAV:response element. Its value is defined only
in the context of a particular query result. The value is a string representing
the score, an integer from zero to 10000 inclusive, where a higher value
indicates a higher score (e.g. more relevant).
Modified DTD fragment for DAV:propstat:
responsedescription?, score?) >
Clients should note that, in general, it is not meaningful to compare
the numeric values of scores from two different query results unless both were
executed by the same underlying search system on the same collection of
resources.
TOC
5.16.2.
Ordering by Score
To order search results by their score, the DAV:score element may be added
as child to the DAV:orderby element (in place of a DAV:prop element).
TOC
5.16.3.
Examples
The example below shows a search for the phrase "Peter Forsberg".
Depending on its support for content-based searching, a server MAY treat
this as a search for documents that contain the words "Peter" and "Forsberg".
The example below shows a search for resources that contain "Peter" and
"Forsberg".
TOC
5.17.
Limiting the Result Set
The DAV:limit XML element contains requested limits from the client
to limit the size of the reply or amount of effort expended by the server.
The DAV:nresults XML element contains a requested maximum number
of DAV:response elements to be returned in the response body.
The server MAY disregard this limit. The value of this element is an
unsigned integer.
TOC
5.17.1.
Relationship to Result Ordering
If the result set is both limited by DAV:limit and ordered according to
DAV:orderby, the results that are included in the response document SHOULD be
those that order highest.
TOC
5.18.
The 'caseless' XML Attribute
The "caseless" attribute allows clients to specify caseless matching behavior
instead of character-by-character matching for DAV:basicsearch operators.
The possible values for "caseless" are "yes" or "no". The default value is
server-specified. Caseless matching SHOULD be implemented as defined in
Section 5.18
of the Unicode Standard (
[UNICODE5]
The Unicode Consortium, “The Unicode Standard - Version 5.0,” November 2006.
).
Support for the "caseless" attribute is optional. A server should
respond with a status of 422 if it is used but cannot be supported.
TOC
5.19.
Query Schema for DAV:basicsearch
The DAV:basicsearch grammar defines a search criteria that is
a Boolean-valued expression, and allows for an arbitrary set of properties
to be included in the result record. The result set may be sorted on a
set of property values. Accordingly the DTD for schema discovery for this
grammar allows the server to express:
the set of properties that may be either searched, returned, or used
to sort, and a hint about the data type of such properties
the set of optional operators defined by the resource.
TOC
5.19.1.
DTD for DAV:basicsearch QSD
searchable?, selectable?, sortable?,
caseless?)>
The DAV:properties element holds a list of descriptions of properties.
The DAV:operators element describes the optional operators
that may be used in a DAV:where element.
TOC
5.19.2.
DAV:propdesc Element
Each instance of a DAV:propdesc element describes the property
or properties in the DAV:prop element it contains. All subsequent
elements are descriptions that apply to those properties. All descriptions
are optional and may appear in any order. Servers SHOULD support all the
descriptions defined here, and MAY define others.
DASL defines five descriptions. The first, DAV:datatype, provides
a hint about the type of the property value, and may be useful to a user
interface prompting for a value. The remaining four (DAV:searchable,
DAV:selectable, DAV:sortable, and DAV:caseless)
identify portions of the query (DAV:where, DAV:select,
and DAV:orderby, respectively). If a property has a description
for a section, then the server MUST allow the property to be used in that
section. These descriptions are optional. If a property does not have such
a description, or is not described at all, then the server MAY still allow
the property to be used in the corresponding section.
TOC
5.19.2.1.
DAV:any-other-property
This element can be used in place of DAV:prop to describe properties of
WebDAV properties not mentioned in any other DAV:prop element. For instance,
this can be used to indicate that all other properties are searchable and selectable
without giving details about their types (a typical scenario for dead properties).
TOC
5.19.3.
The DAV:datatype Property Description
The DAV:datatype element contains a single XML element that provides
a hint about the domain of the property, which may be useful to a user
interface prompting for a value to be used in a query.
Data types are identified by an element name. Where appropriate, a server SHOULD
use the simple data types defined in
[XS2]
Biron, P., Malhotra, A., and World Wide Web Consortium, “XML Schema Part 2: Datatypes Second Edition,” October 2004.
Examples from
[XS2]
Biron, P., Malhotra, A., and World Wide Web Consortium, “XML Schema Part 2: Datatypes Second Edition,” October 2004.
, Section 3:
Qualified name
Example
xs:boolean
true, false, 1, 0
xs:string
Foobar
xs:dateTime
1994-11-05T08:15:5Z
xs:float
.314159265358979E+1
xs:integer
-259, 23
If the data type of a property is not given, then the data type defaults
to xs:string.
TOC
5.19.4.
The DAV:searchable Property Description
If this element is present, then the server MUST allow this property to
appear within a DAV:where element where an operator allows a property.
Allowing a search does not mean that the property is guaranteed to be defined
on every resource in the scope, it only indicates the server's willingness
to check.
TOC
5.19.5.
The DAV:selectable Property Description
This element indicates that the property may appear in the DAV:select
element.
TOC
5.19.6.
The DAV:sortable Property Description
This element indicates that the property may appear in the DAV:orderby
element.
TOC
5.19.7.
The DAV:caseless Property Description
This element only applies to properties whose data type is "xs:string"
and derived data types as per the DAV:datatype property description. Its presence indicates
that compares performed for searches, and the comparisons for ordering
results on the string property will be caseless (the default is
character-by-character).
TOC
5.19.8.
The DAV:operators XML Element
The DAV:operators element describes every optional operator supported
in a query. (Mandatory operators are not listed since they are mandatory
and permit no variation in syntax.). All optional operators that are supported
MUST be listed in the DAV:operators element.
The listing for an operator, contained in an DAV:opdesc element,
consists of the operator (as an empty element), followed by one
element for each operand. The operand MUST be either DAV:operand-property,
DAV:operand-literal or DAV:operand-typed-literal, which indicate that the
operand in the corresponding position is a property, a literal value or
a typed literal value, respectively.
If an operator is polymorphic (allows more than one operand syntax) then
each permitted syntax MUST be listed separately.
The DAV:opdesc element MAY have a "allow-pcdata" attribute (defaulting to
"no"). A value of "yes" indicates that the operator can contain character
data, as it is the case with DAV:contains (see
Section 5.16
DAV:contains
).
Definition of additional operators using this format is NOT RECOMMENDED.
TOC
5.19.9.
Example of Query Schema for DAV:basicsearch
This response lists four properties. The data type of the last three properties
is not given, so it defaults to xs:string. All are selectable, and the first
three may be searched. All but the last may be used in a sort. Of the optional
DAV operators, DAV:contains and DAV:like are supported.
Note: The schema discovery defined here does not provide for discovery of
supported values of the "caseless" attribute. This may require that the reply
also list the mandatory operators.
TOC
6.
Internationalization Considerations
Properties may be language-tagged using the xml:lang attribute (see
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
, Section 4.3). The optional operators
DAV:language-defined (
Section 5.12.1
DAV:language-defined (optional)
and DAV:language-matches (
Section 5.12.2
DAV:language-matches (optional)
allow to express conditions on the language tagging information.
TOC
7.
Security Considerations
This section is provided to detail issues concerning security implications
of which DASL applications need to be aware. All of the security considerations
of HTTP/1.1 (
[RFC2616]
Fielding, R., Gettys, J., Mogul, J., Nielsen, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1,” June 1999.
and WebDAV (
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
) also apply to DASL. In addition, this section will include
security risks inherent in searching and retrieval of resource properties
and content.
A query MUST NOT allow clients to retrieve information that wouldn't have
been available through the GET or PROPFIND methods in the first place. In
particular:
Query constraints on WebDAV properties for which the client does not
have read access need to be evaluated as if the property did not
exist (see
Section 5.5.3
Treatment of NULL Values
).
Query constraints on content (as with DAV:contains, defined in
Section 5.16
DAV:contains
for which the client does not have read access need to be evaluated as
if a GET would return a 4xx status code.
A server should prepare for denial of service attacks. For example a
client may issue a query for which the result set is expensive to calculate
or transmit because many resources match or must be evaluated.
TOC
7.1.
Implications of XML External Entities
XML supports a facility known as "external entities", defined in
Section 4.2.2 of
[XML]
Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and F. Yergeau, “Extensible Markup Language (XML) 1.0 (Fourth Edition),” August 2006.
, which instruct an XML processor to retrieve and perform
an inline include of XML located at a particular URI. An external XML entity
can be used to append or modify the document type declaration (DTD) associated
with an XML document. An external XML entity can also be used to include
XML within the content of an XML document. For non-validating XML, such
as the XML used in this specification, including an external XML entity
is not required by
[XML]
Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and F. Yergeau, “Extensible Markup Language (XML) 1.0 (Fourth Edition),” August 2006.
. However,
[XML]
Bray, T., Paoli, J., Sperberg-McQueen, C., Maler, E., and F. Yergeau, “Extensible Markup Language (XML) 1.0 (Fourth Edition),” August 2006.
does state that an XML
processor may, at its discretion, include the external XML entity.
External XML entities have no inherent trustworthiness and are subject
to all the attacks that are endemic to any HTTP GET request. Furthermore,
it is possible for an external XML entity to modify the DTD, and hence
affect the final form of an XML document, in the worst case significantly
modifying its semantics, or exposing the XML processor to the security
risks discussed in
[RFC3023]
Makoto, M., St.Laurent, S., and D. Kohn, “XML Media Types,” January 2001.
. Therefore, implementers must be aware that
external XML entities should be treated as untrustworthy.
There is also the scalability risk that would accompany a widely deployed
application which made use of external XML entities. In this situation,
it is possible that there would be significant numbers of requests for
one external XML entity, potentially overloading any server which fields
requests for the resource containing the external XML entity.
TOC
8.
Scalability
Query grammars are identified by URIs. Applications SHOULD NOT attempt
to retrieve these URIs even if they appear to be retrievable (for example,
those that begin with "http://")
TOC
9.
IANA Considerations
This document uses the namespace defined in Section 21 of
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
for XML
elements.
TOC
9.1.
HTTP Headers
This document specifies the HTTP header listed below, to be added to the
permanent HTTP header registry defined in
[RFC3864]
Klyne, G., Nottingham, M., and J. Mogul, “Registration Procedures for Message Header Fields,” September 2004.
TOC
9.1.1.
DASL
Header field name:
DASL
Applicable protocol:
http
Status:
standard
Author/Change controller:
IETF
Specification document:
this specification (
Section 3.2
The DASL Response Header
TOC
10.
Contributors
This document is based on prior work on the DASL protocol done by the WebDAV
DASL working group until the year 2000 -- namely by Alan Babich, Jim Davis,
Rick Henderson, Dale Lowry, Saveen Reddy and Surendra Reddy.
TOC
11.
Acknowledgements
This document has benefited from thoughtful discussion by Lisa Dusseault,
Javier Godoy,
Sung Kim, Chris Newman, Elias Sinderson, Martin Wallmer, Keith Wannamaker, Jim Whitehead
and Kevin Wiggen.
TOC
12.
References
TOC
12.1. Normative References
[RFC2119]
Bradner, S.
, “
Key words for use in RFCs to Indicate Requirement Levels
,” BCP 14, RFC 2119, March 1997.
[RFC2616]
Fielding, R.
Gettys, J.
Mogul, J.
Nielsen, H.
Masinter, L.
Leach, P.
, and
T. Berners-Lee
, “
Hypertext Transfer Protocol -- HTTP/1.1
,” RFC 2616, June 1999.
[RFC3023]
Makoto, M.
St.Laurent, S.
, and
D. Kohn
, “
XML Media Types
,” RFC 3023, January 2001.
[RFC3253]
Clemm, G.
Amsden, J.
Ellison, T.
Kaler, C.
, and
J. Whitehead
, “
Versioning Extensions to WebDAV
,” RFC 3253, March 2002.
[RFC3744]
Clemm, G.
Reschke, J.
Sedlar, E.
, and
J. Whitehead
, “
Web Distributed Authoring and Versioning (WebDAV) Access Control Protocol
,” RFC 3744, May 2004.
[RFC3986]
Berners-Lee, T.
Fielding, R.
, and
L. Masinter
, “
Uniform Resource Identifier (URI): Generic Syntax
,” STD 66, RFC 3986, January 2005.
[RFC4918]
Dusseault, L., Ed.
, “
HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV)
,” RFC 4918, June 2007.
[RFC5234]
Crocker, D., Ed.
and
P. Overell
, “
Augmented BNF for Syntax Specifications: ABNF
,” STD 68, RFC 5234, January 2008.
[XML]
Bray, T.
Paoli, J.
Sperberg-McQueen, C.
Maler, E.
, and
F. Yergeau
, “
Extensible Markup Language (XML) 1.0 (Fourth Edition)
,” W3C REC-xml-20060816, August 2006.
[XPATH]
Clark, J.
and
S. DeRose
, “
XML Path Language (XPath) Version 1.0
,” W3C REC-xpath-19991116, November 1999.
[XPATHFUNC]
Malhotra, A.
Melton, J.
, and
N. Walsh
, “
XQuery 1.0 and XPath 2.0 Functions and Operators
,” W3C REC-xpath-functions-20070123, January 2007.
[XS1]
Thompson, H.
Beech, D.
Maloney, M.
Mendelsohn, N.
, and
World Wide Web Consortium
, “
XML Schema Part 1: Structures
,” W3C REC-xmlschema-1-20041028, October 2004.
[XS2]
Biron, P.
Malhotra, A.
, and
World Wide Web Consortium
, “
XML Schema Part 2: Datatypes Second Edition
,” W3C REC-xmlschema-2-20041028, October 2004.
TOC
12.2. Informative References
[BCP47]
Phillips, A. and M. Davis, “
Matching of Language Tags
,” BCP 47, RFC 4647, September 2006.
[DASL]
Reddy, S.
Lowry, D.
Reddy, S.
Henderson, R.
Davis, J.
, and
A. Babich
, “
DAV Searching & Locating
,” draft-ietf-dasl-protocol-00 (work in progress), July 1999.
[DASLREQ]
Davis, J.
Reddy, S.
, and
J. Slein
, “
Requirements for DAV Searching and Locating
,” February 1999.
This is an updated version of the Internet Draft "draft-ietf-dasl-requirements-00",
but obviously never was submitted to the IETF.
[RFC3864]
Klyne, G., Nottingham, M., and J. Mogul, “
Registration Procedures for Message Header Fields
,” BCP 90, RFC 3864, September 2004.
[RFC4437]
Whitehead, J.
Clemm, G.
, and
J. Reschke, Ed.
, “
Web Distributed Authoring and Versioning (WebDAV) Redirect Reference Resources
,” RFC 4437, March 2006.
[RFC4790]
Newman, C.
Duerst, M.
, and
A. Gulbrandsen
, “
Internet Application Protocol Collation Registry
,” RFC 4790, March 2007.
[SQL99]
Milton, J., “Database Language SQL Part 2: Foundation (SQL/Foundation),” ISO ISO/IEC 9075-2:1999 (E), July 1999.
[UNICODE5]
The Unicode Consortium, “
The Unicode Standard - Version 5.0
,” Addison-Wesley , November 2006.
ISBN 0321480910
[draft-ietf-webdav-bind]
Clemm, G.
Crawford, J.
Reschke, J., Ed.
, and
J. Whitehead
, “
Binding Extensions to Web Distributed Authoring and Versioning (WebDAV)
,” draft-ietf-webdav-bind-20 (work in progress), November 2007.
TOC
Appendix A.
Three-Valued Logic in DAV:basicsearch
ANSI standard three valued logic is used when evaluating the search condition
(as defined in the ANSI standard SQL specifications, for example in ANSI
X3.135-1992, section 8.12, pp. 188-189, section 8.2, p. 169, General Rule
1)a), etc.).
ANSI standard three valued logic is undoubtedly the most widely practiced
method of dealing with the issues of properties in the search condition
not having a value (e.g., being null or not defined) for the resource under
scan, and with undefined expressions in the search condition (e.g., division
by zero, etc.). Three valued logic works as follows.
Undefined expressions are expressions for which the value of the expression
is not defined. Undefined expressions are a completely separate concept
from the truth value UNKNOWN, which is, in fact, well defined. Property
names and literal constants are considered expressions for purposes of
this section. If a property in the current resource under scan has not
been set to a value, then
the value of that property is undefined for the resource under scan. DASL
1.0 has no arithmetic division operator, but if it did, division by zero
would be an undefined arithmetic expression.
If any subpart of an arithmetic, string, or datetime subexpression is
undefined, the whole arithmetic, string, or datetime subexpression is undefined.
There are no manifest constants to explicitly represent undefined number,
string, or datetime values.
Since a Boolean value is ultimately returned by the search condition,
arithmetic, string, and datetime expressions are always arguments to other
operators. Examples of operators that convert arithmetic, string, and datetime
expressions to Boolean values are the six relational operators ("greater
than", "less than", "equals", etc.). If either or both operands of a relational
operator have undefined values, then the relational operator evaluates
to UNKNOWN. Otherwise, the relational operator evaluates to TRUE or FALSE,
depending upon the outcome of the comparison.
The Boolean operators DAV:and, DAV:or and DAV:not
are evaluated according to the following rules:
not UNKNOWN = UNKNOWN
UNKNOWN and TRUE = UNKNOWN
UNKNOWN and FALSE = FALSE
UNKNOWN and UNKNOWN = UNKNOWN
UNKNOWN or TRUE = TRUE
UNKNOWN or FALSE = UNKNOWN
UNKNOWN or UNKNOWN = UNKNOWN
TOC
Appendix B.
Candidates for Future Protocol Extensions
This Section summarizes issues which have been raised during the development
of this specification, but for which no resolution could be found with the
constraints in place. Future revisions of this specification should revisit
these issues, though.
TOC
B.1.
Collation Support
Matching and sorting of textual data relies on collations. With respect
to WebDAV SEARCH, a combination of various design approaches could be used:
Require server support for specific collations.
Require that the server can advertise which collations it supports.
Allow a client to select the collation to be used.
In practice, the current implementations of WebDAV SEARCH usually rely
on backends they do not control, and for which collation information may
not be available. To make things worse, implementations of the DAV:basicsearch grammar
frequently need to combine data from multiple underlying stores (such as
properties and full text content), and thus collation support may vary based
on the operator or property.
Another open issue is what collation formalism to support. At the time of
this writing, the two specifications below seem to provide the
necessary framework and thus may be the base for future work on collation
support in WebDAV SEARCH:
"Internet Application Protocol Collation Registry" (
[RFC4790]
Newman, C., Duerst, M., and A. Gulbrandsen, “Internet Application Protocol Collation Registry,” March 2007.
).
"XQuery 1.0 and XPath 2.0 Functions and Operators" (
[XPATHFUNC]
Malhotra, A., Melton, J., and N. Walsh, “XQuery 1.0 and XPath 2.0 Functions and Operators,” January 2007.
, Section 7.3.1).
TOC
B.2.
Count
DAV:basicsearch does not allow a request that returns the count of matching
resources.
A protocol extension would need to extend DAV:select, and also modify the
DAV:multistatus response format.
TOC
B.3.
Diagnostics for Unsupported Queries
There are many reasons why a given query may not be supported by a server.
Query Schema Discovery (
Section 4
Query Schema Discovery: QSD
) can be used to discover some
constraints, but not all.
Future revisions should consider the introduction of specific condition
codes (
[RFC4918]
Dusseault, L., Ed., “HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV),” June 2007.
, Section 16) to these situations.
TOC
B.4.
Language Matching
Section 5.12.2
DAV:language-matches (optional)
defines language matching in
terms of the XPath "lang" function (
[XPATH]
Clark, J. and S. DeRose, “XML Path Language (XPath) Version 1.0,” November 1999.
, Section 4.3).
Future revisions should consider building on
[BCP47]
Phillips, A. and M. Davis, “Matching of Language Tags,” September 2006.
instead.
TOC
B.5.
Matching Media Types
Matching media types using the DAV:getcontenttype property and the DAV:like
operator is hard due to DAV:getcontenttype also allowing parameters.
A new operator specifically designed for the purpose of matching media types
probably would simplify things a lot. See
for a specific proposal.
TOC
B.6.
Query by Name
DAV:basicsearch operates on the properties (and optionally the contents)
of resources, and thus doesn't really allow matching on parts of the
resource's URI. See
for a proposed extension covering this use case.
TOC
B.7.
Result Paging
A frequently discussed feature is the ability to specifically request
the "next" set of results, when either the server decided to truncate
the result, or the client explicitly asked for a limited set (for
instance, using the DAV:limit element defined in
Section 5.17
Limiting the Result Set
).
In this case, it would be desirable if the server could keep the full
query result, and provide a new URI identifying a separate result resource,
allowing the client to retrieve additional data through GET requests,
and remove the result through a DELETE request.
TOC
B.8.
Search Scope Discovery
Given a Search Arbiter resource, there's currently no way to discover
programmatically the supported sets of search scopes. Future revisions
of this specification could specify a scope discovery mechanism, similar
to the Query Schema Discovery defined in
Section 4
Query Schema Discovery: QSD
TOC
Appendix C.
Change Log (to be removed by RFC Editor before publication)
TOC
C.1.
From draft-davis-dasl-protocol-xxx
Feb 14, 1998
Initial Draft
Feb 28, 1998
Referring to DASL as an extension to HTTP/1.1 rather than DAV.
Added new sections "Notational Conventions", "Protocol Model", "Security
Considerations".
Changed section 3 to "Elements of Protocol".
Added some stuff to introduction.
Added "result set" terminology.
Added "IANA Considerations".
Mar 9, 1998
Moved sub-headings of "Elements of Protocol" to first level and removed
"Elements of Protocol" Heading.
Added an sentence in introduction explaining that this is a "sketch"
of a protocol.
Mar 11, 1998
Added orderby, data typing, three valued logic, query schema property,
and element definitions for schema for basicsearch.
April 8, 1998
- made changes based on last week's DASL BOF.
May 8, 1998
Removed most of DAV:searcherror; converted to DAV:searchredirect
Altered DAV:basicsearch grammar to use avoid use of ANY in DTD
June 17, 1998
-Added details on Query Schema Discovery
-Shortened list of data types
June 23, 1998
moved data types before change history
rewrote the data types section
removed the casesensitive element and replace with the casesensitive
attribute
added the casesensitive attribute to the DTD for all operations that
might work on a string
Jul 20, 1998
A series of changes. See Author's meeting minutes for details.
July 28, 1998
Changes as per author's meeting. QSD uses SEARCH, not PROPFIND.
Moved text around to keep concepts nearby.
Boolean literals are 1 and 0, not T and F.
contains changed to contentspassthrough.
Renamed rank to score.
July 28, 1998
Added Dale Lowry as Author
September 4, 1998
Added 422 as response when query lists unimplemented operators.
DAV:literal declares a default value for xml:space, 'preserve'
(see XML spec, section 2.10)
moved to new XML namespace syntax
September 22, 1998
Changed "simplesearch" to "basicsearch"
Changed isnull to isdefined
Defined NULLness as having a 404 or 403 response
used ENTITY syntax in DTD
Added redirect
October 9, 1998
Fixed a series of typographical and formatting errors.
Modified the section of three-valued logic to use a table rather than
a text description of the role of UNKNOWN in expressions.
November 2, 1998
Added the DAV:contains operator.
Removed the DAV:contentpassthrough operator.
November 18, 1998
Various author comments for submission
June 3, 1999
Cosmetic and minor editorial changes only. Fix nits reported by Jim Whitehead
in email of April 26, 1999. Converted to HTML from Word 97, manually.
April 20, 2000
Removed redirection feature, since 301/302 suffices. Removed Query Schema Discovery (former chapter 4). Everyone agrees this is a useful feature, but it is apparently too difficult to define at this time, and it is not essential for DASL.
TOC
C.2.
since start of draft-reschke-webdav-search
October 09, 2001
Added Julian Reschke as author.
Chapter about QSD re-added.
Formatted into RFC2629-compliant XML document.
Added first comments.
ID version number kicked up to draft-dasl-protocol-03.
October 17, 2001
Updated address information for Jim Davis.
Added issue of datatype vocabularies.
Updated issue descriptions for grammar discovery,
added issues on query schema DTD.
Fixed typos in XML examples.
December 17, 2001
Re-introduced split between normative and non-normative references.
January 05, 2002
Version bumped up to 04. Started work on resolving the issues identified
in the previous version.
January 14, 2002
Fixed some XML typos.
January 22, 2002
Closed issues naming-of-elements. Fixed query search DTD and added option
to discover properties of "other" (non-listed) properties.
January 25, 2002
Changed into private submission and added reference to historic DASL draft.
Marked reference to DASL requirements non-normative.
Updated reference to latest deltav spec.
January 29, 2002
Added feedback from and updated contact info for Alan Babich.
Included open issues collected in
February 8, 2002
Made sure that all artwork fits into 72 characters wide text.
February 18, 2002
Changed Insufficient storage handling (multistatus). Moved is-collection to
operators and added to DTD. Made scope/depth mandatory.
February 20, 2002
Updated reference to SQL99.
February 28, 2002
"Non-normative References" -> "Informative References". Abstract updated.
Consistently specify a charset when using text/xml (no change bars). Do
not attempt to define PROPFIND's entity encoding (take out specific references
to text/xml). Remove irrelevant headers (Connection:) from examples (no
change bars). Added issue on querying based on DAV:href. Updated introduction
to indicate relationship to DASL draft. Updated HTTP reference from
RFC2068 to RFC2616. Updated XML reference to XML 1.0 2nd edition.
March 1, 2002
Removed superfluous namespace decl in 2.4.2. Reopened JW14 and suggest
to drop xml:space support.
March 3, 2002
Removed "xml:space" feature on DAV:literal. Added issue about string
comparison vs. collations vs. xml:lang. Updated some of the open issues
with details from JimW's original mail in April 1999. Resolved scope vs
relative URI references. Resolved issues about DAV:ascending (added to
index) and the BNF for DAV:like (changed "octets" to "characters").
March 8, 2002
Updated reference to DeltaV (now RFC3253). Added Martin Wallmer's comments,
moved JW5 into DAV:basicsearch section.
March 11, 2002
Closed open issues regaring the type of search arbiters (JW3) and their
discovery (JW9). Rephrased requirements on multistatus response bodies
(propstat only if properties were selected, removed requirement for
responsedescription).
March 23, 2002
RFC2376 -> RFC3023. Added missing first names of authors. OPTIONS added
to example for DAV:supported-method-set.
TOC
C.3.
since draft-reschke-webdav-search-00
March 29, 2002
Abstract doesn't refer to DASL WG anymore.
April 7, 2002
Fixed section title (wrong property name supported-search-grammar-set.
Changed DAV:casesensitve to "casesensitive" (it wasn't in the DAV:
namespace after all).
May 28, 2002
Updated some issues with Jim Davis's comments.
June 10, 2002
Added proposal for different method for query schema discovery, not
using pseudo-properties.
June 25, 2002
QSD marshalling rewritten. Added issue "isdefined-optional".
TOC
C.4.
since draft-reschke-webdav-search-01
July 04, 2002
Added issue "scope-collection".
July 08, 2002
Closed issue "scope-collection".
August 12, 2002
Added issues "results-vs-binds" and "select-allprop".
October 22, 2002
Added issue "undefined-expressions".
November 18, 2002
Changed example host names (no change tracking).
November 25, 2002
Updated issue "DB2/DB7". Closed issues "undefined expressions",
"isdefined-optional" and "select-allprop".
TOC
C.5.
since draft-reschke-webdav-search-02
November 27, 2002
Added issues "undefined-properties", "like-exactlyone" and "like-wildcard-adjacent".
Closed issue "query-on-href". Added acknowledgments section.
November 28, 2002
Closed issue "like-exactlyone". Added issue "mixed-content-properties".
December 14, 2002
Closed issues "undefined-properties", "results-vs-binds",
"mixed-content-properties".
Updated issue "like-wildcard-adjacent".
Added informative reference to BIND draft. Updated reference to ACL
draft.
January 9, 2003
Removed duplicate section on invalid scopes. Added comments to some
open issues. Closed issues JW25/26, score-pseudo-property and null-ordering.
January 10, 2003
Issue limit-vs-ordering plus resolution. Closed issue JW17/JW24b.
January 14, 2003
New issue order-precedence. Started resolution of DB2/DB7.
January 15, 2003
Started spec of DAV:typed-literal.
January 17, 2003
Fix one DAV:like/DAV:getcontenttype example (add / to like expression,
make case-insensitive).
January 28, 2003
Update issue(s) result-truncation, JW24d.
Fixed response headers in OPTIONS example.
Added issue qsd-optional.
Closed issue(s) order-precedence, case-insensitivity-name.
February 07, 2003
Added issue scope-vs-versions. score-pseudo-property: allow DAV:orderby
to explicitly specify DAV:score.
TOC
C.6.
since draft-reschke-webdav-search-03
April 24, 2003
Fixed two "?" vs "_" issues (not updated in last draft).
June 13, 2003
Improve index.
TOC
C.7.
since draft-reschke-webdav-search-04
July 7, 2003
Typo fixed (propstat without status element).
August 11, 2003
Remove superfluous IP and copyright sections.
September 09, 2003
Added issues "2.4-multiple-uris" and "5.1-name-filtering".
October 06, 2003
Fix misplaced section end in 5.11, add table formatting. Enhance table
formatting in 5.18.3. Updated ACL and BIND references. Added XPATH
reference. Closed issue JW24d by adding new optional operators. Updated more
open issues, added issues from January meeting. Add K. Wiggen to Acknowledgements.
Add Contributors section for the authors of the original draft.
Close issue "scope-vs-versions" (optional feature added). Close (new)
issue "1.3-import-DTD-terminology". Add issue "1.3-import-requirements-terminology".
October 07, 2003
Typos fixed. Moved statement about DAV: namespace usage into separate
(sub-)section. Closed "1.3-import-requirements-terminology". Update
I18N Considerations with new xml:lang support info (see issue JW24d).
Close issue "DB2/DB7" (remaining typing issues are now summarized
in issue "typed-literal"). Fix misplaced section end in section 7.
Started change to use RFC3253-style method definitions and error
marshalling.
October 08, 2003
Remove obsolete language that allowed reporting invalid scopes and such
inside multistatus. Add new issue "5.4.2-scope-vs-redirects".
TOC
C.8.
since draft-reschke-webdav-search-05
October 11, 2003
Separate DAV:basicsearch DTD into separate figures for better maintainability.
Update DTD with language-* operators and typed-literal element (optional).
October 14, 2003
Close issue "5.4.2-multiple-scope".
November 04, 2003
Update reference from CaseMap to UNICODE4, section 5.18.
November 16, 2003
Updated issue "5.1-name-filtering".
November 24, 2003
Reformatted scope description (collection vs. non-collection).
November 30, 2003
Add issue "5_media_type_match".
February 6, 2004
Updated all references.
TOC
C.9.
since draft-reschke-webdav-search-06
July 05, 2004
Fix table in Appendix "Three-Valued Logic in DAV:basicsearch".
September 14, 2004
Fix inconsistent DTD in section 5.2 and 5.4 for scope element.
September 30, 2004
Rewrite editorial note and abstract. Update references (remove unneeded
XMLNS, update ref to ACL and BIND specs).
TOC
C.10.
since draft-reschke-webdav-search-07
October 01, 2004
Fix previous section heading (no change tracking).
October 13, 2004
Fix DTD entry for is-collection.
November 1, 2004
Fix DTD fragment query-schema-discovery.
December 11, 2004
Update BIND reference.
January 01, 2005
Fix DASL and DASLREQ references.
February 06, 2005
Update XS2 reference.
February 11, 2005
Rewrite "like" and "DASL" (response header) grammar in ABNF.
May 5, 2005
Update references. Close issue "abnf" (only use ABNF when applicable).
TOC
C.11.
since draft-reschke-webdav-search-08
May 06, 2005
Fix document title.
September 25, 2005
Update BIND reference.
October 05, 2005
Update RFC4234 reference.
October 22, 2005
Author's address update.
February 12, 2006
Update BIND reference.
March 16, 2006
Add typed literals to QSD.
August 20, 2006
Update XML reference.
August 28, 2006
Add issues "5.3-select-count" (open) and "5.4-clarify-depth" (resolved).
Update BIND reference (again).
TOC
C.12.
since draft-reschke-webdav-search-09
December 1, 2006
Fix ABNF for DASL header.
December 16, 2006
Close issue "qsd-optional", leave QSD optional. Close issue "2.4-multiple-uris",
suggesting that servers should only return one response element per resource in
case of multiple bindings.
Add and resolve issues "authentication" and "cleanup-iana" (adding the header registration for
"DASL").
Re-write rational for using the DAV: namespace, although this is a non-WG
submission.
January 4, 2007
Close issue "JW16b/JW24a", being related to "language-comparison".
Add
Appendix B
Candidates for Future Protocol Extensions
Close issues "language-comparison", "5_media_type_match",
"5.1-name-filtering" and "5.3-select-count" as "won't fix", and add appendices accordingly.
January 24, 2007
Update BIND reference. Close issue "5.4.2-scope-vs-redirects".
Close issue "typed-literal": specify in terms of the XPATH 2.9 casting mechanism.
Close issue "1.3-apply-condition-code-terminology" (no changes).
TOC
C.13.
since draft-reschke-webdav-search-10
January 29, 2007
Issue "result-truncation": Add appendix describing the open issue of
Result Paging. Describe the mechanism of marshalling truncated results
in a new normative subsection (leave the actual example where it was).
Add and resolve issues "rfc2606-compliance" and "response-format".
Update contact information for Alan Babich, Jim Davis and Surendra Reddy (no change tracking).
February 8, 2007
Update BIND reference.
TOC
C.14.
since draft-reschke-webdav-search-11
Update: draft-newman-i18n-comparator-14 is RFC4790.
Update: RFC2518 replaced by draft-ietf-webdav-rfc2518bis.
Updated BIND reference.
Minor tweaks to intro (document organization and relation to DASL).
TOC
C.15.
since draft-reschke-webdav-search-12
Update: draft-ietf-webdav-rfc2518bis replaced by RFC4918.
Updated BIND reference.
TOC
C.16.
since draft-reschke-webdav-search-13
Open and close issue "qsd-req-validity".
Updated BIND reference.
TOC
C.17.
since draft-reschke-webdav-search-14
RFC4234 obsoleted by RFC5234.
Add and resolve issues "5.19.8-opdesc-vs-contains" and "dtd".
Add clarifications about the behaviour when literal values are not compatible
with the type of a comparison.
TOC
C.18.
since draft-reschke-webdav-search-15
Minor editorial improvements.
Fix description of DAV:scope/DAV:href to use proper URI terminology, add reference
to RFC 3986.
Clarify list nature of DASL header.
Clarify that the DAV:like pattern ABNF is defined in terms of Unicode code points.
Update to UNICODE5.
Aim for standards track (affects introduction to
Appendix B
Candidates for Future Protocol Extensions
).
Thus, make the dependency on
[RFC4437]
Whitehead, J., Clemm, G., and J. Reschke, Ed., “Web Distributed Authoring and Versioning (WebDAV) Redirect Reference Resources,” March 2006.
clearly optional,
and make the reference informative.
Also, mention BCP 47 as candidate for future changes to language matching.
Mention definition of additional condition codes as candidate for future changes.
Consider DAV:contains in Security Considerations.
Update Surendra's and Alan's contact information.
Mention search scope discovery as future extensions. Add a SHOULD level
requirement for DAV:basicsearch search arbiters to support their own
URI as search scope.
TOC
C.19.
since draft-reschke-webdav-search-16
In DASL header registration tepmplate, set "Status" to "standard".
Add missing bracket in DTD (
Section 4.1
Additional SEARCH Semantics
).
Fix broken and missing XML namespace declarations in examples.
TOC
C.20.
since draft-reschke-webdav-search-17
Typo fixed ("SHOULD not" -> "SHOULD NOT"). Fixed namespace name "http://jennicam.org" to
use a RFC 2606 compliant domain.
State that SEARCH is a safe method.
Clarify that the DASL header should be added to the permanent registry.
Add and resolve issue "ordering-vs-limiting".
TOC
Appendix D.
Resolved issues (to be removed by RFC Editor before publication)
Issues that were either rejected or resolved in this version of this
document.
TOC
D.1.
safeness
In Section 2:
Type: edit
julian.reschke@greenbytes.de (2008-08-02):
State that the SEARCH method is safe.
Resolution (2008-08-03):
Done.
TOC
D.2.
ordering-vs-limiting
In Section 5.17.1:
Type: change
jbarone@xythos.com (2008-08-04):
I read this to mean that the full results should first be ordered by
the server, and then send back the requested limit. This seems to
contradict what's specified in section 2.3.1, where the results are
limited and then ordered (if I'm reading it correctly). I think these 2
sections should be consistent with each other.
Resolution (2008-08-17):
Relax requirement to SHOULD.
TOC
Appendix E.
Open issues (to be removed by RFC Editor prior to publication)
TOC
E.1.
edit
Type: edit
julian.reschke@greenbytes.de (2004-07-05):
Umbrella issue for editorial fixes/enhancements.
TOC
Index
caseless attribute
Condition Names
DAV:search-grammar-discovery-supported (pre)
DAV:search-grammar-supported (pre)
DAV:search-multiple-scope-supported (pre)
DAV:search-scope-valid (pre)
Criteria
DAV:and
DAV:ascending
DAV:contains
DAV:depth
DAV:descending
DAV:eq
caseless attribute
DAV:from
DAV:gt
DAV:gte
DAV:include-versions
DAV:is-collection
DAV:is-defined
DAV:language-defined
DAV:language-matches
DAV:like
DAV:limit
DAV:literal
DAV:lt
DAV:lte
DAV:not
DAV:nresults
DAV:or
DAV:orderby
DAV:scope
DAV:score
relationship to DAV:orderby
DAV:search-grammar-discovery-supported precondition
DAV:search-grammar-supported precondition
DAV:search-multiple-scope-supported precondition
DAV:search-scope-valid precondition
DAV:select
DAV:supported-query-grammar-set property
DAV:typed-literal
DAV:where
Methods
OPTIONS method
DASL response header
Properties
DAV:supported-query-grammar-set
Query
Query Grammar
Query Grammar Discovery
using live property
using OPTIONS
Query Schema
Result
Result Record
Result Record Definition
Result Set
Result Set Truncation
Example
Scope
Search Arbiter
SEARCH method
Search Modifier
Sort Specification
TOC
Authors' Addresses
Julian F. Reschke (editor)
greenbytes GmbH
Hafenweg 16
Muenster, NW 48155
Germany
Phone:
+49 251 2807760
Email:
julian.reschke@greenbytes.de
URI:
Surendra Reddy
Mitrix, Inc.
303 Twin Dolphin Drive, Suite 600-37
Redwood City, CA 94065
U.S.A.
Phone:
+1 408 500 1135
Email:
Surendra.Reddy@mitrix.com
Jim Davis
27 Borden Street
Toronto, Ontario M5S 2M8
Canada
Phone:
+1 416 929 5854
Email:
jrd3@alum.mit.edu
URI:
Alan Babich
IBM Corporation
3565 Harbor Blvd.
Costa Mesa, CA 92626
U.S.A.
Phone:
+1 714 327 3403
Email:
ababich@us.ibm.com
TOC
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Copyright © The IETF Trust (2008).
This document is subject to the rights,
licenses and restrictions contained in BCP 78,
and except as set forth therein,
the authors retain all their rights.
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Alan Babich
Surendra Reddy
Julian Reschke
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