Abstract

The identification of resources on the Web by URI alone may not be sufficient, as other factors such as HTTP content negotiation might come into play. This issue is particularly significant for quality assurance testing, conformance claims, and reporting languages like the W3C Evaluation And Report Language (EARL). This document provides a representation of the HTTP vocabulary in RDF, to allow quality assurance tools to record the HTTP headers that have been exchanged between a client and a server. The RDF terms defined by this document represent the core HTTP specification defined by RFC 2616, as well as additional HTTP headers registered by IANA. These terms can also be used to record HTTPS exchanges.

Status of this document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

This Working Draft of the HTTP Vocabulary in RDF document was published on 8 September 2008 by the Evaluation and Repair Tools Working Group (ERT WG). It is an update of the previous HTTP Vocabulary in RDF Working Draft of 23 March 2007, and addresses the comments received since (see history of document changes). This document is part of the W3C Evaluation And Report Language (EARL). It is expected to be the last working draft before publication as a W3C Working Group Note.

[Editor's note: change text appropriately]

The RDF terms defined by this document can be used to extend the Evaluation And Report Language (EARL) 1.0 Schema, but can also be used separately to record an HTTP exchange between a client and a server for any purpose. The Working Group encourages feedback about the approach, as well as about the completeness and maturity of this document by developers and researchers who have interest in a representation of the HTTP vocabulary in RDF format. Feedback from the W3C Quality Assurance Interest Group, the W3C Semantic Web Interest Group, and the Protocol for Web Description Resources Working Group is particularly welcome. Please send comments on this document by @@@ CHANGE @@@29 September 2008 to the public mailing list of the working group public-wai-ert@w3.org. The archives of the working group mailing list are publicly available.

[Editor's note: change date for comments]

Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.

This document was produced by a group operating under the 5 February 2004 W3C Patent Policy. The group does not expect this document to become a W3C Recommendation. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

Table of Contents

  1. Introduction
  2. Classes
  3. Properties
  4. Conformance

Appendices

  1. A practical Example
  2. Terms
  3. Schema in RDF/XML
  4. References
  5. Document Changes

1 Introduction

This document defines a representation of the Hypertext Transfer Protocol (HTTP) using the Resource Description Framework (RDF). It defines a collection of RDF classes and properties that represent the HTTP vocabulary as defined by the HTTP specification. These RDF terms can be used to record HTTP or HTTPS request and response messages in RDF format, such as by automated Web accessibility evaluation tools that want to describe Web resources, including the various headers exchanged between the client and server during content negotiation. More usage examples for these terms are described in section 1.2 Use Cases.

This document is not intended to be a clarification or extension of the different concepts of the HTTP specification. The HTTP specification is defined by a series of Request for Comments (RFC) publications and other documentation, including RFC 2616 and RFC 4229. These are listed in Appendix C: References.

Additionally this document assumes the following background knowledge:

By default, the vocabulary introduced by this document uses names starting with upper-case letters for classes and names starting with lower-case letters for properties. The keywords must, required, recommended, should, may, and optional are used in accordance with [RFC2119].

1.1 Namespaces

The RDF representation of the HTTP vocabulary defined by this document uses the namespace http://www.w3.org/2006/http#. The prefix http is used throughout this document to denote this namespace. Table 1 presents the namespaces used by this document. The prefix notation presents the typical conventions used in the Web and in this document to denote a given namespace, and can be freely modified. Table 2 presents additional RDF data used by this document.

Table 1: namespaces used by this document.
Namespace prefix Namespace URI Description
http http://www.w3.org/2006/http# Namespace for the core terms of HTTP vocabulary in RDF.
cnt http://www.w3.org/2008/content# Namespace for Representing Content in RDF [Content in RDF].
dc http://purl.org/dc/elements/1.1/ Namespace for the Dublin Core Metadata Element Set.
dct http://purl.org/dc/terms/ Namespace for the Dublin Core Metadata Terms.
rdf http://www.w3.org/1999/02/22-rdf-syntax-ns# Namespace for RDF [RDF].
Table 2: RDF data used by this document.
URI Description
http://www.w3.org/2008/http-headers HTTP headers as registered by the IANA (see [RFC4229], [Permanent Headers], and [Provisional Headers]).
http://www.w3.org/2008/http-methods HTTP methods for requests.
http://www.w3.org/2008/http-statusCodes HTTP status codes for responses.

1.2 Use Cases

The following (non-exhaustive) list of use cases aims to highlight some of the different usages of the terms provided by this document:

Reporting Test Results
When Web resources are tested, for example for accessibility or other quality assurance testing, it may be significant to record the exact headers exchanged between the server and the client during the testing. Without a record of the exchanged headers, it may not be possible to re-identify the exact resource (or representation of the resource) that has been tested. The terms provided by this document allow quality assurance tools to record the HTTP exchange between a client and a server, for example to record the POST parameters or the headers used during content negotiation. The terms provided by this document can be used in combination with the W3C Evaluation And Report Language (EARL) [EARL].
Precising Conformance Claims
Conformance claims that are made about a Web resource or group of Web resource, are sometimes only applicable under certain constraints. For example, conformance of a Web site to the W3C Web Content Accessibility Guidelines (WCAG) [WCAG], may only be applicable for a certain language of the Web site that is using language negotiation. When provding machine-readable conformance claims, for example using the W3C Protocol for Describing Web Resources (POWDER): Description Resources [POWDER-DR], it is important to precise any such constraints that may apply.
Debugging Web Applications
Web applications using client-side scripting such as AJAX may exchange additional HTTP messages with the server without using a different URI. In order to debug such Web applications, it must be possible to reconstruct the exact history of the states through which the Web application passed. Web authoring tools that are designed to develop and debug Web applications could use the terms provided by this document to record the exact HTTP messages exchanged bewteen a client and a server. This information could be provided to the developer as a log to help debug errors in the Web application..
Indexing Information Resources
When indexing RDF information resources that are available through the HTTP protocol (also called "scuttering" in Semantic Web parlance), it is often useful to record information about the HTTP request and response messages that were exchanged, along with the data for later use. In some instances, different representations of the RDF information may be retrieved from the server depending on the HTTP headers and paramters exchanged. The terms provided by this document can be used to supplement the collected data with the HTTP messages as part of a comprehensive indexing repository.

1.3 Limitations

There are also notable schema limitations with regards to security and privacy since the content recorded by this vocabulary could potentially contain sensitive information, for example authentication information in HTTP headers or other information (login user name, passwords, etc.) within the body of the message. Since the schema of this document is limited to terms defined by the HTTP vocabulary, security and privacy considerations need to be made at the application level. For example, certain parts of the data may be restricted to appropriate user permissions or obfuscated.

2 Classes

This section defines RDF classes for the HTTP 1.1 specification according to [RFC 2616].

2.1 Connection Class

A connection that is used for the HTTP transfer.

Related Properties

Examples

Example 2.1: A Connection resource.

<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="http://www.w3.org/2006/http#"
    xml:base="http://www.example.org/connection#">
  <http:Connection rdf:ID="conn">
    <http:connectionAuthority>www.example.org:80</http:connectionAuthority>
    <http:requests rdf:parseType="Collection">
      <http:Request rdf:ID="req0"/>
      <http:Request rdf:ID="req1"/>
    </http:requests>
  </http:Connection>
</rdf:RDF>

2.2 Message Class

An HTTP message.

Related Properties

It may be appropriate to provide additional information about the Message by using the following from external vocabularies:

dc:date external link
Message date (see the usage of this property in requests and responses).

Examples

Example 2.2: A Message resource.

<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="http://www.w3.org/2006/http#"
    xmlns:dc="http://purl.org/dc/elements/1.1/"
    xml:base="http://example.org/message#">
  <http:Message rdf:ID="mess0">
    <http:httpVersion>1.1</http:httpVersion>
    <dc:date>2007-09-13</dc:date>
    <http:headers rdf:parseType="Collection">
      <http:MessageHeader rdf:ID="mh0"/>
      <http:MessageHeader rdf:ID="mh1"/>
    </http:headers>
    <http:body>
      <cnt:Content rdf:ID="cont0"/>
    </http:body>
  </http:Message>
  <http:MessageHeader rdf:ID="mh0">
    <!-- ... -->
  </http:MessageHeader>
  <http:MessageHeader rdf:ID="mh1">
    <!-- ... -->
  </http:MessageHeader>
</rdf:RDF>

There are two subclasses from the http:Message class: http:Request and http:Response.

2.2.1 Request Class

An HTTP request. The http:Request class is a subclass of the http:Message class.

Related Properties

The dc:date property when used in a Request resource represents the date the request was sent by the client.

Examples

Example 2.3: A Request resource.

<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="http://www.w3.org/2006/http#"
    xmlns:dc="http://purl.org/dc/elements/1.1/"
    xml:base="http://example.org/reqs#">
  <http:Request rdf:ID="reqs0">
    <http:abs_path>/</http:abs_path>
    <http:methodName>GET</http:methodName>
    <http:method rdf:resource="http://www.w3.org/2008/http-methods#GET"/>
    <http:response rdf:resource="#resp0"/>
    <dc:date>2007-09-13</dc:date>
    <http:httpVersion>1.1</http:httpVersion>
    <http:headers rdf:parseType="Collection">
      <http:MessageHeader rdf:about="#mh0"/>
      <http:MessageHeader rdf:about="#mh1"/>
    </http:headers>
  </http:Request>
  <http:MessageHeader rdf:ID="mh0">
    <!-- ... -->
  </http:MessageHeader>
  <http:MessageHeader rdf:ID="mh1">
    <!-- ... -->
  </http:MessageHeader>
</rdf:RDF>

2.2.2 Response Class

An HTTP response. The http:Response class is a subclass of the http:Message class.

Related Properties

The dc:date property when used in a Response resource represents the date the response was received by the client.

Examples

Example 2.4: A Response resource.

<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="http://www.w3.org/2006/http#"
    xmlns:dc="http://purl.org/dc/elements/1.1/"
    xmlns:cnt="http://www.w3.org/2008/content#"
    xml:base="http://example.org/resp#">
  <http:Response rdf:ID="resp0">
    <http:httpVersion>1.1</http:httpVersion>
    <dc:date>2008-01-11</dc:date>
    <http:statusCodeNumber>200</http:statusCodeNumber>
    <http:statusCode rdf:resource="http://www.w3.org/2008/http-statusCodes#statusCode200"/>
    <http:headers rdf:parseType="Collection">
      <http:MessageHeader rdf:about="#mh0"/>
      <http:MessageHeader rdf:about="#mh1"/>
    </http:headers>
    <http:body>
      <cnt:Content rdf:ID="cont0"/>
    </http:body>
  </http:Response>
  <http:MessageHeader rdf:ID="mh0">
    <!-- ... -->
  </http:MessageHeader>
  <http:MessageHeader rdf:ID="mh1">
    <!-- ... -->
  </http:MessageHeader>
</rdf:RDF>

2.3 MessageHeader Class

A header in an HTTP message.

Related Properties

Examples

Example 2.5: A MessageHeader resource.

<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="http://www.w3.org/2006/http#"
    xml:base="http://example.org/mh#">
  <http:MessageHeader rdf:ID="mh0">
    <http:fieldValue>text/html, image/png, image/gif;q=0.8</http:fieldValue>
    <http:fieldName>Accept</http:fieldName>
    <http:headerName rdf:resource="http://www.w3.org/2008/http-headers#accept"/>
    <http:headerElements rdf:parseType="Collection">
      <http:HeaderElement rdf:about="#he0"/>
      <http:HeaderElement rdf:about="#he1"/>
      <http:HeaderElement rdf:about="#he2"/>
    </http:headerElements>
  </http:MessageHeader>
  <http:HeaderElement rdf:ID="he0">
    <!-- ... -->
  </http:HeaderElement>
  <http:HeaderElement rdf:ID="he1">
    <!-- ... -->
  </http:HeaderElement>
  <http:HeaderElement rdf:ID="he2">
    <!-- ... -->
  </http:HeaderElement>
</rdf:RDF>

2.4 HeaderElement Class

An element in a header value, if a Message Header value can be decomposed into several parts.

Related Properties

Examples

Example 2.6: A HeaderElement resource.

<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="http://www.w3.org/2006/http#"
    xml:base="http://example.org/he#">
  <http:HeaderElement rdf:ID="he0">
    <http:elementName>image/gif</http:elementName>
    <http:params rdf:parseType="Collection">
      <http:Param rdf:ID="param0"/>
    </http:params>
  </http:HeaderElement>
  <http:Param rdf:ID="param0">
    <!-- ... -->
  </http:Param>
</rdf:RDF>

2.5 Param Class

A parameter in a Header Element.

Related Properties

Examples

Example 2.7: A Param resource.

<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="http://www.w3.org/2006/http#"
    xml:base="http://example.org/param#">
  <http:Param rdf:ID="param0">
    <http:paramName>q</http:paramName>
    <http:paramValue>0.8</http:paramValue>
  </http:Param>
</rdf:RDF>

2.6 Method Class

The HTTP 1.1 specification defines eight methods: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, CONNECT. The RDF graph available in RDF/XML at http://www.w3.org/2008/http-methods provides http:Method resources for each of these to be used as objects for the http:method property. A resource of type http:Method represents the name of a method used with HTTP.

Related Properties

2.7 StatusCode Class

[HTTP Status Codes] is a registry for status codes too be used in HTTP. The RDF graph available in RDF/XML at http://www.w3.org/2008/http-statusCodes provides http:StatusCode resources for each of these to be used as objects for the http:statusCode property. A resource of type http:StatusCode represents a status code.

Related Properties

2.8 HeaderName Class

Header names to be used in HTTP are registered by the IANA (see [RFC4229], [Permanent Headers], and [Provisional Headers]). The RDF graph available in RDF/XML at http://www.w3.org/2008/http-headers provides http:HeaderName resources for each of these to be used as objects for the http:headerName property. A resource of type http:HeaderName represents the name of a header used with HTTP.

Related Properties

Properties defined by this document:

3 Properties

This section defines RDF properties for the HTTP 1.1 specification according to [RFC 2616].

3.1 body Property

[Editor's note: Removed multiple versions, only used Base64Content. We must decide what mechanism to use to connect cnt:TextContent/cnt:XMLContent resources to cnt:Base64Content resources, e.g. via dct:source.]

This property relates a resource object of the type Message to a resource object of the type cnt:Content or a subclass thereof to be the Message's entity body as defined in [RFC 2616]. HTTP bodies are series of bytes. Thus for the resource object, it is appropriate to point to a cnt:Base64Content resource (see [Content in RDF] for more information on content representations in RDF).

Domain:
http:Message
Range:
cnt:Base64Content external link

Examples

Example 3.1: The entity body of a message.

<rdf:RDF
    xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="http://www.w3.org/2006/http#"
    xmlns:dc="http://purl.org/dc/elements/1.1/"
    xml:base="http://example.org/message#">
  <http:Message rdf:ID="mess0">
    <http:body>
      <cnt:Base64Content rdf:ID="cont0-bin"/>
    </http:body>
  </http:Message>
  <cnt:Base64Content rdf:ID="cont0-bin">
    <!-- ... -->
  </cnt:Base64Content>
</rdf:RDF>

3.2 connectionAuthority Property

Connection authority - server host and port for a connection.

Domain:
http:Connection
Range:
Literal

3.3 elementName Property

Header element name (Literal).

Domain:
http:HeaderElement
Range:
Literal

3.4 elementValue Property

Header element value (Literal).

Domain:
http:HeaderElement
Range:
Literal

3.5 fieldName Property

Header name (Literal).

Domain:
http:MessageHeader
Range:
Literal

3.6 fieldValue Property

Header value (Literal).

Domain:
http:MessageHeader
Range:
unspecified

3.7 headers Property

HTTP headers sent with the message.

Domain:
http:Message
Range:
unspecified

3.8 headerElements Property

Header value elements.

Domain:
http:MessageHeader
Range:
unspecified

3.9 headerName Property

This property relates a resource of type http:MessageHeader to a resource of type http:HeaderName.

Domain:
http:MessageHeader
Range:
http:HeaderName

3.10 httpVersion Property

Property representing the HTTP version number as a Literal (the format is 'digit.digit').

Domain:
http:Message
Range:
Literal

3.11 method Property

HTTP method.

Domain:
http:Request
Range:
http:Method

3.12 methodName Property

HTTP method name (Literal).

Domain:
http:Request
Range:
Literal

3.13 params Property

Header element parameters.

Domain:
http:HeaderElement
Range:
unspecified

3.14 paramName Property

Parameter name.

Domain:
http:Param
Range:
Literal

3.15 paramValue Property

Parameter value.

Domain:
http:Param
Range:
Literal

3.16 reasonPhrase Property

Reason phrase sent by the server.

Domain:
http:Response
Range:
Literal

3.17 requests Property

HTTP requests sent via the connection.

Domain:
http:Connection
Range:
unspecified

3.18 requestURI Property

[Editor's Note: Should we remove the asterisk value?]

The request URI as specified in section 5.1.2 of [RFC 2616]. This vocabulary defines the following sub-properties:

Domain:
http:Request
Range:
unspecified

Conformance Note: The object for this property must be the constant value http:asterisk.

Examples

Example 3.2: The use of the requestURI property.

<http:Request>
  <http:methodName>OPTIONS</http:methodName>
  <http:requestURI rdf:resource="http://www.w3.org/2006/http#asterisk"/>
  ...
</http:Request>

3.18.1 absoluteURI Property

Request URI that is an absolute URI.

Conformance Note: The object for this property must be a Literal (absolute URI).

Examples

Example 3.3: The use of the absoluteURI property.

<http:Request>
  <http:methodName>GET</http:methodName>
  <http:absoluteURI>http://www.example.org:80/foo/bar</http:absoluteURI>
  ...
</http:Request>

3.18.2 abs_path Property

Request URI that is an absolute path.

Conformance Note: The object for this property must be a Literal (absolute path).

Examples

Example 3.4: The use of the abs_path property.

<http:Request>
  <http:methodName>GET</http:methodName>
  <http:abs_path>/foo/bar</http:abs_path>
  ...
</http:Request>

3.18.3 authority Property

Request URI that is an authority.

Conformance Note: The object for this property must be a Literal (host and optional port number).

Examples

Example 3.5: The use of the authority property.

<http:Request>
  <http:methodName>CONNECT</http:methodName>
  <http:authority>www.example.org:80</http:authority>
  ...
</http:Request>

3.19 response Property

This property relates a resource of type http:Request to a resource of type http:Response.

Domain:
http:Request
Range:
http:Response

3.20 statusCode Property

This property relates a resource of type http:Response to a resource of type http:StatusCode.

Domain:
http:Response
Range:
http:StatusCode

3.21 statusCodeNumber Property

The status code sent by the server (Literal).

Domain:
http:Response
Range:
Literal

4 Conformance

This section describes conformance with this HTTP-in-RDF specification. It differentiates between the following entities:

[Editor's note: Need fancier word for "HTTP-in-RDF Graph".]

HTTP-in-RDF Graph
An individual file or collection of files that contain HTTP-in-RDF data
HTTP-in-RDF Producer
A software tool or Web-based application that produces HTTP-in-RDF data
HTTP-in-RDF Consumer
A software tool or Web-based application that processes HTTP-in-RDF data

4.1 Conforming HTTP-in-RDF graphs

Graphs conforming to this HTTP-in-RDF specification must meet the following requirements:

  1. A Connection must have exactly one connection authority (referenced by http:connectionAuthority).
  2. A Connection may have one collection of Requests (referenced by http:requests).
  3. A Message must have exactly one HTTP version (referenced by http:httpVersion).
  4. A Message may have one collection of Message Headers (referenced by http:headers).
  5. A Message may have one message body (referenced by http:body).
  6. A Message may have one date (referenced by dc:date external link).
  7. A Request must have exactly one method name (referenced by http:methodName).
  8. A Request must have exactly one request URI (referenced by http:requestURI).
  9. A Request may be connected to one Method (referenced by http:method).
  10. A Request may be connected to one Response (referenced by http:response).
  11. A Response must have exactly one status code number (referenced by http:statusCodeNumber).
  12. A Response must have exactly one reason phrase (referenced by http:reasonPhrase).
  13. A Response may conected to one Status Code (referenced by http:statusCode).
  14. A Message Header must have exactly one field name (referenced by http:fieldName).
  15. A Message Header must have exactly one field value (referenced by http:fieldValue).
  16. A Message Header may have one header name (referenced by http:headerName).
  17. A Message Header may have one collection of Header Elements (referenced by http:headerElements).
  18. A Header Element must have exactly one element name (referenced by http:elementName).
  19. A Header Element may have one header element value (referenced by http:elementValue).
  20. A Header Element may have one collection of Parameters (referenced by http:params).
  21. A Parameter must have exactly one parameter name (referenced by http:paramName).
  22. A Parameter must have exactly one parameter value (referenced by http:paramValue).
  23. The objects for the headers property must be an RDF Collection of Message Headers.
  24. The objects for the http:headerElements property must be an RDF Collection of Header Elements.
  25. The object for the http:params property must be an RDF Collection of Parameters.
  26. The object for the http:requests property must be an RDF Collection of Requests.
  27. Every instance of cnt:Content external link must conform with the respective specification.

4.2 Conforming Producers

Producers conforming to this EARL 1.0 Schema specification must meet the following requirements:

  1. A Producer must generate conforming graphs
  2. A Producer must be able to generate graphs in RDF/XML serializations and should also support other RDF serializations
  3. A Producer must generate all of the terms summarized in Appendix B: Terms for which there is information available to it

[Editor's note: should conforming producers be required to fully support Content-in-RDF?]

4.3 Conforming Consumers

Consumers conforming to this EARL 1.0 Schema specification must meet the following requirements:

  1. A Consumer must process conforming graphs
  2. A Consumer must process graphs in any RDF/XML serialization and should also support other RDF serializations
  3. A Consumer must process all of the terms summarized in Appendix B: Terms for which there is information available to it

[Editor's note: should conforming consumers be required to fully support Content-in-RDF?]

Appendix A: A practical Example

The following example shows an RDF/XML representation of an HTTP request and response pair.

Scenario Description

A client sends two requests to a server at www.example.org port 80 via HTTP 1.1 GET. With each request, it sends request headers. The first request is for a resource in the document root (/), the second for a resource at /image. While handling the second request the server performs content negotiation respecting the request's Accept header and so sends a PNG image. This is indicated by the response's Vary header.

Resulting RDF/XML

<?xml version="1.0" encoding="utf-8"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:http="http://www.w3.org/2006/http#"
  xmlns:cnt="http://www.w3.org/2008/content#"
  xmlns:dct="http://purl.org/dc/terms/">

  <http:Connection rdf:ID="conn">
    <http:connectionAuthority>www.example.org:80</http:connectionAuthority>
    <http:requests rdf:parseType="Collection">
      <http:Request rdf:about="#req0"/>
      <http:Request rdf:about="#req1"/>
    </http:requests>
  </http:Connection>

  <http:Request rdf:about="#req0">
    <http:httpVersion>1.1</http:httpVersion>
    <http:methodName>GET</http:methodName>
    <http:method rdf:resource="http://www.w3.org/2008/http-methods#GET"/>
    <http:abs_path>/</http:abs_path>
    <http:headers rdf:parseType="Collection">
      <http:MessageHeader>
        <http:fieldName>Host</http:fieldName>
        <http:headerName rdf:resource="http://www.w3.org/2008/http-headers#host"/>
        <http:fieldValue>www.example.org</http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>User-Agent</http:fieldName>
        <http:headerName rdf:resource="http://www.w3.org/2008/http-headers#user-agent"/>
        <http:fieldValue>My User Agent</http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>Accept</http:fieldName>
        <http:headerName rdf:resource="http://www.w3.org/2008/http-headers#accept"/>
        <http:fieldValue>text/html, image/png, image/gif;q=0.8</http:fieldValue>
        <http:headerElements rdf:parseType="Collection">
          <http:HeaderElement>
            <http:elementName>text/html</http:elementName>
          </http:HeaderElement>
          <http:HeaderElement>
            <http:elementName>image/png</http:elementName>
          </http:HeaderElement>
          <http:HeaderElement>
            <http:elementName>image/gif</http:elementName>
            <http:params rdf:parseType="Collection">
              <http:Param>
                <http:paramName>q</http:paramName>
                <http:paramValue>0.8</http:paramValue>
              </http:Param>
            </http:params>
          </http:HeaderElement>
        </http:headerElements>
      </http:MessageHeader>
    </http:headers>
    <http:response rdf:resource="#resp0"/>
  </http:Request>

  <http:Request rdf:about="#req1">
    <http:httpVersion>1.1</http:httpVersion>
    <http:methodName>GET</http:methodName>
    <http:method rdf:resource="http://www.w3.org/2008/http-methods#GET"/>
    <http:abs_path>/image</http:abs_path>
    <http:headers rdf:parseType="Collection">
      <http:MessageHeader>
        <http:fieldName>Host</http:fieldName>
        <http:headerName rdf:resource="http://www.w3.org/2008/http-headers#host"/>
        <http:fieldValue>www.example.org</http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>User-Agent</http:fieldName>
        <http:headerName rdf:resource="http://www.w3.org/2008/http-headers#user-agent"/>
        <http:fieldValue>My User Agent</http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>Accept</http:fieldName>
        <http:headerName rdf:resource="http://www.w3.org/2008/http-headers#accept"/>
        <http:fieldValue>image/png, image/gif;q=0.8</http:fieldValue>
        <http:headerElements rdf:parseType="Collection">
          <http:HeaderElement>
            <http:elementName>image/png</http:elementName>
          </http:HeaderElement>
          <http:HeaderElement>
            <http:elementName>image/gif</http:elementName>
            <http:params rdf:parseType="Collection">
              <http:Param>
                <http:paramName>q</http:paramName>
                <http:paramValue>0.8</http:paramValue>
              </http:Param>
            </http:params>
          </http:HeaderElement>
        </http:headerElements>
      </http:MessageHeader>
    </http:headers>
    <http:response rdf:resource="#resp1"/>
  </http:Request>

  <http:Response rdf:ID="resp0">
    <http:httpVersion>1.1</http:httpVersion>
    <http:statusCodeNumber>200</http:statusCodeNumber>
    <http:statusCode rdf:resource="http://www.w3.org/2008/http-statusCodes#200"/>
    <http:reasonPhrase>OK</http:reasonPhrase>
    <http:headers rdf:parseType="Collection">
      <http:MessageHeader>
        <http:fieldName>Date</http:fieldName>
        <http:headerName rdf:resource="http://www.w3.org/2008/http-headers#date"/>
        <http:fieldValue>.......</http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>Content-Type</http:fieldName>
        <http:headerName rdf:resource="http://www.w3.org/2008/http-headers#content-type"/>
        <http:fieldValue>text/html; charset=utf-8</http:fieldValue>
        <http:headerElements rdf:parseType="Collection">
          <http:HeaderElement>
            <http:elementName>text/html</http:elementName>
            <http:params rdf:parseType="Collection">
              <http:Param>
                <http:paramName>charset</http:paramName>
                <http:paramValue>utf-8</http:paramValue>
              </http:Param>
            </http:params>
          </http:HeaderElement>
        </http:headerElements>
      </http:MessageHeader>
    </http:headers>
    <http:body>
      <cnt:Base64Content rdf:ID="cont0-bin">
        <cnt:bytes rdf:datatype="http://www.w3.org/2001/XMLSchema#base64Binary"
          >ajrq9qguojbglj48z..........</cnt:bytes>
      </cnt:Base64Content>
    </http:body>
  </http:Response>

  <cnt:XMLContent rdf:ID="cont0-xml">
    <dct:source rdf:resource="#cont0-bin"/>
    <cnt:xmlLeadingMisc rdf:parseType="Literal"><!-- This is the start of the document -->
</cnt:xmlLeadingMisc>
    <cnt:docTypeDecl>
      <cnt:DocTypeDecl>
        <cnt:dtdName>html</cnt:dtdName>
        <cnt:publicId>-//W3C//DTD XHTML 1.0 Strict//EN</cnt:publicId>
        <cnt:systemId rdf:datatype="http://www.w3.org/2001/XMLSchema#anyURI"
          >http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd</cnt:systemId>
      </cnt:DocTypeDecl>
    </cnt:docTypeDecl>
    <cnt:xmlRest rdf:parseType="Literal"><html xmlns="http://www.w3.org/1999/xhtml" lang="en">
  <head>
    <title>My document</title>
  </head>
  <body>
    <p><!-- ...... --></p>
  </body>
</html></cnt:xmlRest>
  </cnt:XMLContent>

  <http:Response rdf:ID="resp1">
    <http:httpVersion>1.1</http:httpVersion>
    <http:statusCodeNumber>200</http:statusCodeNumber>
    <http:statusCode rdf:resource="http://www.w3.org/2008/http-statusCodes#200"/>
    <http:reasonPhrase>OK</http:reasonPhrase>
    <http:headers rdf:parseType="Collection">
      <http:MessageHeader>
        <http:fieldName>Date</http:fieldName>
        <http:headerName rdf:resource="http://www.w3.org/2008/http-headers#date"/>
        <http:fieldValue>.......</http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>Content-Type</http:fieldName>
        <http:headerName rdf:resource="http://www.w3.org/2008/http-headers#content-type"/>
        <http:fieldValue>image/png</http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>Vary</http:fieldName>
        <http:headerName rdf:resource="http://www.w3.org/2008/http-headers#vary"/>
        <http:fieldValue>accept</http:fieldValue>
        <http:headerElements rdf:parseType="Collection">
          <http:HeaderElement>
            <http:elementName>accept</http:elementName>
          </http:HeaderElement>
        </http:headerElements>
      </http:MessageHeader>
    </http:headers>
    <http:body>
      <cnt:Base64Content>
        <cnt:bytes rdf:datatype="http://www.w3.org/2001/XMLSchema#base64Binary"
          >qouh3908t38hohfrf..........</cnt:bytes>
      </cnt:Base64Content>
    </http:body>
  </http:Response>

</rdf:RDF>

Appendix B: Terms

The following terms are defined by this specification:

Classes

Classes in the HTTP namespace
Class name Label Comment Refinements Related properties
http:Connection Connection A connection used for HTTP transfer. - http:connectionAuthority, http:requests
http:HeaderElement Header Element A part of a deconstructed header value. - http:elementName, http:elementValue, http:params
http:HeaderName Header Name The header name. -
http:Message Message An HTTP message. http:Request, http:Response http:httpVersion, dc:date, http:body, http:headers
http:MessageHeader Message Header A header in an HTTP message. - http:fieldName, http:fieldValue, http:headerName, http:headerElements
http:Method Method The HTTP method used for a request. -
http:Param Parameter A parameter for a part of a header value - http:paramName, http:paramValue
http:Request Request An HTTP request. - http:methodName, http:requestURI, http:method, http:response
http:Response Response An HTTP response. - http:statusCodeNumber, http:reasonPhrase, http:statusCode
http:StatusCode Status Code The status code of an HTTP response. -

Properties

Properties in the HTTP namespace
Property name Label Comment Domain Range
http:body Entity body The entity body of an HTTP message. http:Message cnt:Base64Content
http:connectionAuthority Connection authority The authority of a connection used for the HTTP transfer http:Connection RDF Literal
http:elementName Header element name The name of a header element http:HeaderElement RDF Literal
http:elementValue Header element value The value of a header element. http:HeaderElement RDF Literal
http:fieldName Field name The name of an HTTP header field. http:MessageHeader RDF Literal
http:fieldValue Field value The value of an HTTP header field. http:MessageHeader RDF Literal
http:headerElements Header elements The deconstructed parts of an HTTP header value. http:MessageHeader Collection of http:HeaderElement
http:headerName Header name The name of an HTTP header. http:MessageHeader http:HeaderName
http:headers Headers The headers in an HTTP message. http:Message Collection of http:MessageHeader
http:httpVersion HTTP Version The HTTP version of an HTTP message. http:Message RDF Literal
http:method Method The HTTP method used for the HTTP request. http:Request http:Method
http:methodName Method name The HTTP method name used for the HTTP request. http:Request RDF Literal
http:paramName Parameter name The name of a parameter in a part of a deconstructed HTTP header value. http:Param RDF Literal
http:params Parameters The parameters in a part of a deconstructed HTTP header value. http:HeaderElement Collection of http:Param
http:paramValue Parameter value The value of a parameter in a part of a deconstructed HTTP header value. http:Param RDF Literal
http:reasonPhrase Reason phrase The reason phrase (status text) of an HTTP response. http:Response RDF Literal
http:requests Requests The HTTP requests made via a connection. http:Connection Collection of http:Request
http:requestURI Request URI The request URI of an HTTP request. http:Request RDF Literal
http:response Response The HTTP response sent in answer to an HTTP request. http:Request http:Response
http:statusCode Status code The status code of an HTTP response. http:Response http:StatusCode
http:statusCodeNumber Status code number The status code number of an HTTP response. http:Response RDF Literal

Values

Values in the HTTP namespace
Value Name Label Used in Description
http:asterisk Asterisk http:requestURI An asterisk used as request URI

Appendix C: Schema in RDF/XML

An RDF Schema can be found at @@@TBD@@@.

[Editor's note: add link to RDF schema]

Appendix D: References

[Content in RDF]
Representing Content in RDF - Johannes Koch, Carlos A Velasco (eds.). W3C Working Draft 17 July 2008.
[EARL]
Evaluation and Report Language (EARL) Overview - W3C
[HTTP Status Codes]
"HTTP Status Code Registry" - IANA.
[OWL]
Web Ontology Language (OWL) Overview - W3C
[Permanent Headers]
Permanent Message Header Field Names - IANA.
[Provisional Headers]
Provisional Message Header Field Names - IANA.
[POWDER-DR]
Protocol for Web Description Resources (POWDER): Description Resources - K. Smith, P. Archer, A. Perego (eds.). W3C Working Draft 17 March 2008.
[POWDER-GR]
Protocol for Web Description Resources (POWDER): Grouping of Resources - P. Archer, A. Perego, K. Smith (eds.). W3C Working Draft 24 March 2008.
[RDF]
Resource Description Framework (RDF) Overview - W3C
[RDF-PRIMER]
RDF Primer. W3C Recommendation, 10 February 2004.
http://www.w3.org/TR/rdf-primer/
[RDFS]
RDF Vocabulary Description Language 1.0: RDF Schema. W3C Recommendation 10 February 2004.
http://www.w3.org/TR/rdf-schema/
[RFC2119]
Request for Comments: 2119. Key words for use in RFCs to Indicate Requirement Levels - IETF March 1997.
[RFC2616]
Hypertext Transfer Protocol -- HTTP/1.1 - R. Fielding, J. Gettys, J. Mogul, H. Frystyk Nielsen, L. Masinter, P. Leach and T. Berners-Lee. IETF June 1999.
[RFC4229]
HTTP Header Field Registrations - M. Nottingham, J. Mogul. IETF December 2005.
[WCAG]
Web Content Accessibility Guidelines (WCAG) Overview - W3C.
[XML]
Extensible Markup Language (XML) 1.0 (Fourth Edition). W3C Recommendation 16 August 2006, edited in place 29 September 2006.
http://www.w3.org/TR/xml/

Appendix E: Document Changes

[Editor's note: add changes from this version to WD-HTTP-in-RDF-20080908]

Besides several editorial changes, the following is a list of substantial changes since the 23 March, 2007 Working Draft: