HTTP Vocabulary in RDF

W3C Working Draft 8 September 2008

This version:

https://www.w3.org/TR/2008/WD-HTTP-in-RDF-20080908

Latest version:

https://www.w3.org/TR/HTTP-in-RDF/

Previous version:

https://www.w3.org/TR/2007/WD-HTTP-in-RDF-20070323/

Editors:

Johannes Koch, Fraunhofer Institute for Applied Information Technology (FIT)

Carlos A Velasco, Fraunhofer Institute for Applied Information Technology (FIT)

Shadi Abou-Zahra, W3C/WAI

Copyright © 2008 W3C^® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark and document use rules apply.

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 https://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.

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 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.

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.

1. Introduction

This document defines a representation of the Hyper Text 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 1.3. 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 D: References. This document is also not intended to be an introduction to RDF, the reader is referred to the RDF Primer and RDF specifications [RDF] for this purpose.

1.1. Namespaces

The RDF representation of the HTTP vocabulary defined by this document uses the namespace https://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 (rdfs and owl namespaces are normally only used in the schema); and Table 2 presentes additional RDF data 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.

1.2. Naming Conventions

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].

1.3. 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. [Editor Note: the Working Group is exploring the relationship to POWDER].

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.

1.4. 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 and Properties

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

2.1. Connection Class

A resource of type Connection represents a connection that is used for the HTTP transfer. The following properties may appear in nodes of type Connection:

connectionAuthority

Property representing the connected authority (server host and port) as a Literal.

requests

Property representing the HTTP requests sent via the connection as a Collection of Request resources.

<rdf:RDF
    xmlns:rdf="https://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="https://www.w3.org/2006/http#"
    xml:base="https://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

A resource of type Message represents an HTTP message. The following properties may appear in resources of type Message:

httpVersion

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

dc:date

Property representing a date as a Literal (see the usage of this property in requests and responses).

headers

Property representing the HTTP headers sent with the message as a Collection of MessageHeader resources.

body

Property pointing to a resource representing the message body (see 2.2.1 Body Property).

<rdf:RDF
    xmlns:rdf="https://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="https://www.w3.org/2006/http#"
    xmlns:dc="https://purl.org/dc/elements/1.1/"
    xml:base="https://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>
</rdf:RDF>

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

2.2.1. Body Property

The body property represents an HTTP entity body as defined in [RFC 2616]. It can appear in resources of both type Request or Response. The object for this property must be a resource of the type cnt:Content or a subclass thereof. HTTP bodies are series of bytes. Thus it is always possible to point to a cnt:Base64Content resource. If the body is textual content, you can also point to a cnt:TextContent resource. If the body is XML content, you can also point to a cnt:XMLContent resource (see [Content in RDF] for more information on content representations in RDF).

Note: for multiple representations of the same entity body, an RDF container must be used to describe the relationship. For example the rdf:Bag container may be useful if all representations are equivalent, or in other cases rdf:Alt may be useful if there is a prefered representation with alternatives.

<rdf:RDF
    xmlns:rdf="https://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="https://www.w3.org/2006/http#"
    xmlns:dc="https://purl.org/dc/elements/1.1/"
    xml:base="https://example.org/message#">
  <http:Message rdf:ID="mess0">
    <http:body>
      <rdf:Alt>
        <rdf:li>
          <cnt:XMLContent rdf:ID="cont0"/>
        <rdf:li>
        <rdf:li>
          <cnt:TextContent rdf:ID="cont0-alt1"/>
        <rdf:li>
        <rdf:li>
          <cnt:Base64Content rdf:ID="cont0-alt2"/>
        <rdf:li>
      </rdf:Alt>
    </http:body>
  </http:Message>
</rdf:RDF>

2.3. Request Class

The Request class is a subclass of the Message class. A resource of this type represents an HTTP request. Additional to the properties mentioned in 2.2 Message Class, the following properties may appear in resources of type Request:

methodName

Property representing the method name as a Literal.

method

Property poining to a Method resource representing the HTTP method (optional, see 3.1. Methods).

requestURI

Property (or one of its sub-properties) representing the request URI (see also 2.3.1 Request URI Property).

response

Property pointing to a Response resource representing the response resulting from this request (see 2.4. Response Class).

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

<rdf:RDF
    xmlns:rdf="https://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="https://www.w3.org/2006/http#"
    xmlns:dc="https://purl.org/dc/elements/1.1/"
    xml:base="https://example.org/reqs#">
  <http:Request rdf:ID="reqs0">
    <http:abs_path>/</http:abs_path>
    <http:methodName>GET</http:methodName>
    <http:method rdf:resource="https://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 rdf:ID="mh1"/>
</rdf:RDF>

2.3.1. Request URI Property

The requestURI property represents the request URI as specified in section 5.1.2 of [RFC 2616]. The value of the property is either the constant value http:asterisk or a Literal value of the absolute URI, the absolute path, or an authority. This vocabulary defines the following sub-properties to reference these values:

absoluteURI

Property to be used when the request URI is an absolute URI.

abs_path

Property to be used when the request URI is an absolute path.

authority

Property to be used when the request URI is an authority.

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

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

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

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

2.4. Response Class

The Response class is a subclass of the Message class. A resource of this type represents an HTTP response as defined in [RFC 2616]. Additional to the properties mentioned in 2.2 Message Class, the following properties may appear in resources of type Response:

statusCodeNumber

Property representing the status code sent by the server as a Literal.

statusCode

Property pointing to a StatusCode resource representing the status code (optional, see 3.2. Status Codes).

reasonPhrase

Property representing the reason phrase sent by the server as a Literal.

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

<rdf:RDF
    xmlns:rdf="https://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="https://www.w3.org/2006/http#"
    xmlns:dc="https://purl.org/dc/elements/1.1/"
    xmlns:cnt="https://www.w3.org/2007/content#"
    xml:base="https://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="https://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="mh1"/>
  <http:MessageHeader rdf:ID="mh0"/>
</rdf:RDF>

2.5. MessageHeader Class

A resource of type MessageHeader represents an HTTP header. The following properties may appear in resources of type MessageHeader:

fieldName

Property representing the header name as a Literal.

headerName

Property pointing to a HeaderName resource representing the header name (optional, see 3.4. Header Names).

fieldValue

Property representing the header value as a Literal.

headerElements

Property representing the header value as a Collection of HeaderElement resources (optional).

<rdf:RDF
    xmlns:rdf="https://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="https://www.w3.org/2006/http#"
    xml:base="https://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="https://www.w3.org/2008/http-header#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 rdf:ID="he2"/>
  <http:HeaderElement rdf:ID="he1"/>
</rdf:RDF>

2.6. HeaderElement Class

A resource of type HeaderElement represents an element in a header value. The following properties may appear in resources of type HeaderElement:

elementName

Property representing the header element name as a Literal.

elementValue

Property representing the header element value as a Literal (optional).

params

Property representing header element parameters as a Collection of Param resources (optional).

<rdf:RDF
    xmlns:rdf="https://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="https://www.w3.org/2006/http#"
    xml:base="https://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>
</rdf:RDF>

2.7. Param Class

A resource of type Param represents an element in a header value parameter. The following properties may appear in resources of type Param:

paramName

Property representing the parameter name as a Literal.

paramValue

Property representing the parameter value as a Literal.

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

3. Predefined Values

This section defines RDF terms for the predefined resources representing values used in HTTP 1.1 specification according to [RFC 2616] or other specifications. A comprehensive example of using these predefined values together with the classes and properties provided in the previous section can be found in Appendix C: Practical Example.

3.1. Request Methods

The HTTP 1.1 specification defines eight methods: OPTIONS, GET, HEAD, POST, PUT, DELETE, TRACE, CONNECT. The resource at https://www.w3.org/2006/http-methods provides Method resources for each of these to be used as objects for the method property. A resource of type Method represents the name of a method used with HTTP.

3.2. Status Codes

[HTTP Status Codes] is a registry for status codes too be used in HTTP. The resource at https://www.w3.org/2006/http-statusCodes provides StatusCode resources for each of these to be used as objects for the statusCode property. A resource of type StatusCode represents a status code.

3.3. Status Code Groups

Status codes in HTTP may be grouped. The resource at https://www.w3.org/2006/http-statusCodes provides StatusCodeGroup resources for some groupings of status codes. A resource of type StatusCodeGroup represents a group of status codes.

3.4. Header Names

Header names to be used in HTTP are registered by the IANA (see [RFC4229], [Permanent Headers], and [Provisional Headers]). The resource at https://www.w3.org/2006/http-header provides HeaderName resources for each of these to be used as objects for the headerName property. A resource of type HeaderName represents the name of a header used with HTTP.

Appendix A: Schema in RDF/XML

<?xml version="1.0"?>
<rdf:RDF
    xmlns:rdf="https://www.w3.org/1999/02/22-rdf-syntax-ns#"
    xmlns:http="https://www.w3.org/2006/http#"
    xmlns:owl="https://www.w3.org/2002/07/owl#"
    xmlns:dc="https://purl.org/dc/elements/1.1/"
    xmlns:xsd="https://www.w3.org/2001/XMLSchema#"
    xmlns:rdfs="https://www.w3.org/2000/01/rdf-schema#"
    xml:base="https://www.w3.org/2006/http">
  <rdf:Description rdf:about="#">
    <rdfs:comment xml:lang="en">A namespace for describing HTTP messages (https://www.w3.org/Protocols/rfc2616/rfc2616.html)</rdfs:comment>
  </rdf:Description>
  <owl:Ontology rdf:about="">
    <owl:imports rdf:resource="https://purl.org/dc/dcam/"/>
    <owl:imports rdf:resource="https://purl.org/dc/elements/1.1/"/>
  </owl:Ontology>
  <!-- Classes -->
  <rdfs:Class rdf:about="#Connection">
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#requests"/>
        <owl:maxCardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:maxCardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#connectionAuthority"/>
        <owl:cardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:cardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:comment xml:lang="en">The connection</rdfs:comment>
    <rdfs:label xml:lang="en">Connection</rdfs:label>
  </rdfs:Class>
  <rdfs:Class rdf:about="#HeaderElement">
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#params"/>
        <owl:maxCardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:maxCardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#elementValue"/>
        <owl:maxCardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:maxCardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#elementName"/>
        <owl:cardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:cardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:comment xml:lang="en">The header element</rdfs:comment>
    <rdfs:label xml:lang="en">Header element</rdfs:label>
  </rdfs:Class>
  <rdfs:Class rdf:about="#HeaderName">
    <rdfs:comment xml:lang="en">The header name</rdfs:comment>
    <rdfs:label xml:lang="en">Header name</rdfs:label>
  </rdfs:Class>
  <rdfs:Class rdf:about="#Message">
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#body"/>
        <owl:maxCardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:maxCardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#headers"/>
        <owl:maxCardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:maxCardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="https://purl.org/dc/elements/1.1/date"/>
        <owl:maxCardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:maxCardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#httpVersion"/>
        <owl:cardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:cardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:comment xml:lang="en">The HTTP message</rdfs:comment>
    <rdfs:label xml:lang="en">Message</rdfs:label>
  </rdfs:Class>
  <rdfs:Class rdf:about="#MessageHeader">
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#headerElements"/>
        <owl:maxCardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:maxCardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#fieldValue"/>
        <owl:cardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:cardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#headerName"/>
        <owl:maxCardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:maxCardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#fieldName"/>
        <owl:cardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:cardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:comment xml:lang="en">The message header</rdfs:comment>
    <rdfs:label xml:lang="en">Message header</rdfs:label>
  </rdfs:Class>
  <rdfs:Class rdf:about="#Method">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:comment xml:lang="en">The HTTP method</rdfs:comment>
    <rdfs:label xml:lang="en">Method</rdfs:label>
  </rdfs:Class>
  <rdfs:Class rdf:about="#Param">
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#paramValue"/>
        <owl:cardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:cardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#paramName"/>
        <owl:cardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:cardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:comment xml:lang="en">The field value parameter</rdfs:comment>
    <rdfs:label xml:lang="en">Parameter</rdfs:label>
  </rdfs:Class>
  <rdfs:Class rdf:about="#Request">
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#response"/>
        <owl:maxCardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:maxCardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#requestURI"/>
        <owl:cardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:cardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#method"/>
        <owl:maxCardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:maxCardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#methodName"/>
        <owl:cardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int"
        >1</owl:cardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:subClassOf rdf:resource="#Message"/>
    <rdfs:comment xml:lang="en">The request</rdfs:comment>
    <rdfs:label xml:lang="en">Request</rdfs:label>
  </rdfs:Class>
  <rdfs:Class rdf:about="#Response">
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#reasonPhrase"/>
        <owl:cardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:cardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:subClassOf>
      <owl:Restriction>
        <owl:onProperty rdf:resource="#statusCode"/>
        <owl:maxCardinality rdf:datatype="https://www.w3.org/2001/XMLSchema#int">1</owl:maxCardinality>
      </owl:Restriction>
    </rdfs:subClassOf>
    <rdfs:isDefinedBy>
      <rdf:Description rdf:about="https://www.rfc-editor.org/rfc/rfc2616.txt">
        <dc:identifier>https://www.rfc-editor.org/rfc/rfc2616.txt</dc:identifier>
        <dc:title xml:lang="en">Hypertext Transfer Protocol -- HTTP/1.1</dc:title>
      </rdf:Description>
    </rdfs:isDefinedBy>
    <rdfs:subClassOf rdf:resource="#Message"/>
    <rdfs:comment xml:lang="en">The response</rdfs:comment>
    <rdfs:label xml:lang="en">Response</rdfs:label>
  </rdfs:Class>
  <rdfs:Class rdf:about="#StatusCode">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:comment xml:lang="en">The status code</rdfs:comment>
    <rdfs:label xml:lang="en">Status code</rdfs:label>
  </rdfs:Class>
  <rdfs:Class rdf:about="#StatusCodeGroup">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:comment xml:lang="en">The tatus code group</rdfs:comment>
    <rdfs:label xml:lang="en">Status code group</rdfs:label>
  </rdfs:Class>
  <!-- Properties -->
  <rdf:Property rdf:about="#absoluteURI">
    <rdfs:subPropertyOf rdf:resource="#requestURI"/>
    <rdfs:comment xml:lang="en">The absolute request URI</rdfs:comment>
    <rdfs:label xml:lang="en">Absolute URI</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#abs_path">
    <rdfs:subPropertyOf rdf:resource="#requestURI"/>
    <rdfs:comment xml:lang="en">The absolute path sort of request URI</rdfs:comment>
    <rdfs:label xml:lang="en">Absolute path</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#authority">
    <rdfs:subPropertyOf rdf:resource="#requestURI"/>
    <rdfs:comment xml:lang="en">The authority sort of request URI</rdfs:comment>
    <rdfs:label xml:lang="en">Authority</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#body">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:domain rdf:resource="#Message"/>
    <rdfs:comment xml:lang="en">The message body; cnt:Content or rdf:Alt/rdf:Bag of cnt:Content</rdfs:comment>
    <rdfs:label xml:lang="en">Body</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#connectionAuthority">
    <rdfs:range rdf:resource="https://www.w3.org/2000/01/rdf-schema#Literal"/>
    <rdfs:domain rdf:resource="#Connection"/>
    <rdfs:comment xml:lang="en">The connection authority</rdfs:comment>
    <rdfs:label xml:lang="en">Connection authority</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#elementName">
    <rdfs:range rdf:resource="https://www.w3.org/2000/01/rdf-schema#Literal"/>
    <rdfs:domain rdf:resource="#HeaderElement"/>
    <rdfs:comment xml:lang="en">The header element name</rdfs:comment>
    <rdfs:label xml:lang="en">Element name</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#elementValue">
    <rdfs:range rdf:resource="https://www.w3.org/2000/01/rdf-schema#Literal"/>
    <rdfs:domain rdf:resource="#HeaderElement"/>
    <rdfs:comment xml:lang="en">The header element value</rdfs:comment>
    <rdfs:label xml:lang="en">Element value</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#fieldName">
    <rdfs:range rdf:resource="https://www.w3.org/2000/01/rdf-schema#Literal"/>
    <rdfs:domain rdf:resource="#MessageHeader"/>
    <rdfs:comment xml:lang="en">The field name; literal header name</rdfs:comment>
    <rdfs:label xml:lang="en">Field name</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#fieldValue">
    <rdfs:domain rdf:resource="#MessageHeader"/>
    <rdfs:comment xml:lang="en">The field value; rdfs:Literal or http:HeaderElement</rdfs:comment>
    <rdfs:label xml:lang="en">Field value</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#headerElements">
    <rdfs:domain rdf:resource="#MessageHeader"/>
    <rdfs:comment xml:lang="en">The header elements; (RDF collection of) http:HeaderElement</rdfs:comment>
    <rdfs:label xml:lang="en">Header elements</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#headerName">
    <rdfs:range rdf:resource="#HeaderName"/>
    <rdfs:domain rdf:resource="#MessageHeader"/>
    <rdfs:comment xml:lang="en">The header name; interpreted field name</rdfs:comment>
    <rdfs:label xml:lang="en">Header name</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#headers">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:domain rdf:resource="#Message"/>
    <rdfs:comment xml:lang="en">The headers; (RDF collection of) http:MessageHeader</rdfs:comment>
    <rdfs:label xml:lang="en">Headers</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#httpVersion">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:range rdf:resource="https://www.w3.org/2000/01/rdf-schema#Literal"/>
    <rdfs:domain rdf:resource="#Message"/>
    <rdfs:comment xml:lang="en">The HTTP version</rdfs:comment>
    <rdfs:label xml:lang="en">HTTP version</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#method">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:range rdf:resource="#Method"/>
    <rdfs:domain rdf:resource="#Request"/>
    <rdfs:comment xml:lang="en">The HTTP method</rdfs:comment>
    <rdfs:label xml:lang="en">Method</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#methodName">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:range rdf:resource="https://www.w3.org/2000/01/rdf-schema#Literal"/>
    <rdfs:domain rdf:resource="#Request"/>
    <rdfs:comment xml:lang="en">The HTTP method name</rdfs:comment>
    <rdfs:label xml:lang="en">Method name</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#paramName">
    <rdfs:range rdf:resource="https://www.w3.org/2000/01/rdf-schema#Literal"/>
    <rdfs:domain rdf:resource="#Param"/>
    <rdfs:comment xml:lang="en">The header parameter name</rdfs:comment>
    <rdfs:label xml:lang="en">Header parameter name</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#paramValue">
    <rdfs:range rdf:resource="https://www.w3.org/2000/01/rdf-schema#Literal"/>
    <rdfs:domain rdf:resource="#Param"/>
    <rdfs:comment xml:lang="en">The header parameter value</rdfs:comment>
    <rdfs:label xml:lang="en">Header parameter value</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#params">
    <rdfs:domain rdf:resource="#HeaderElement"/>
    <rdfs:comment xml:lang="en">The header parameters; (RDF collection of) http:Param</rdfs:comment>
    <rdfs:label xml:lang="en">Header parameters</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#reasonPhrase">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:range rdf:resource="https://www.w3.org/2000/01/rdf-schema#Literal"/>
    <rdfs:domain rdf:resource="#Response"/>
    <rdfs:comment xml:lang="en">The reason phrase (status text)</rdfs:comment>
    <rdfs:label xml:lang="en">Reason phrase</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#requests">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:domain rdf:resource="#Connection"/>
    <rdfs:comment xml:lang="en">The HTTP requests; (RDF collection of) http:Request</rdfs:comment>
    <rdfs:label xml:lang="en">Requests</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#requestURI">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:domain rdf:resource="#Request"/>
    <rdfs:comment xml:lang="en">The request URI; rdfs:Literal or https://www.w3.org/2006/http#asterisk</rdfs:comment>
    <rdfs:label xml:lang="en">Request URI</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#response">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:range rdf:resource="#Response"/>
    <rdfs:domain rdf:resource="#Request"/>
    <rdfs:comment xml:lang="en">The HTTP response</rdfs:comment>
    <rdfs:label xml:lang="en">Response</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#statusCode">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:range rdf:resource="#StatusCode"/>
    <rdfs:domain rdf:resource="#Response"/>
    <rdfs:comment xml:lang="en">The HTTP status code</rdfs:comment>
    <rdfs:label xml:lang="en">Status code</rdfs:label>
  </rdf:Property>
  <rdf:Property rdf:about="#statusCodeNumber">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <rdfs:range rdf:resource="https://www.w3.org/2000/01/rdf-schema#Literal"/>
    <rdfs:domain rdf:resource="#Response"/>
    <rdfs:comment xml:lang="en">The HTTP status code number; rdfs:Literal (typed: 3digit)</rdfs:comment>
    <rdfs:label xml:lang="en">Status code</rdfs:label>
  </rdf:Property>
  <rdf:Description rdf:about="#asterisk">
    <rdfs:isDefinedBy rdf:resource="https://www.rfc-editor.org/rfc/rfc2616.txt"/>
    <dc:description xml:lang="en">The asterisk as a request URI</dc:description>
    <dc:title xml:lang="en">Asterisk</dc:title>
  </rdf:Description>
</rdf:RDF>

Appendix B: Vocabulary Terms

The following terms are defined by this specification:

Classes

Properties

Values

Appendix C: 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="https://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:http="https://www.w3.org/2006/http#"
  xmlns:cnt="https://www.w3.org/2007/content#">
  <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="https://www.w3.org/2008/http-methods#GET"/>@@@TBD@@@
    <http:abs_path>/</http:abs_path>
    <http:headers rdf:parseType="Collection">
      <http:MessageHeader>
        <http:fieldName>Host</http:fieldName>
        <http:headerName rdf:resource="https://www.w3.org/2008/http-header#host"/>@@@TBD@@@
        <http:fieldValue>www.example.org</http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>User-Agent</http:fieldName>
        <http:headerName rdf:resource="https://www.w3.org/2008/http-header#user-agent"/>@@@TBD@@@
        <http:fieldValue>My User Agent</http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>Accept</http:fieldName>
        <http:headerName rdf:resource="https://www.w3.org/2008/http-header#accept"/>@@@TBD@@@
        <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="https://www.w3.org/2008/http-methods#GET"/>@@@TBD@@@
    <http:abs_path>/image</http:abs_path>
    <http:headers rdf:parseType="Collection">
      <http:MessageHeader>
        <http:fieldName>Host</http:fieldName>
        <http:headerName rdf:resource="https://www.w3.org/2008/http-header#host"/>@@@TBD@@@
        <http:fieldValue>www.example.org</http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>User-Agent</http:fieldName>
        <http:headerName rdf:resource="https://www.w3.org/2008/http-header#user-agent"/>@@@TBD@@@
        <http:fieldValue>My User Agent</http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>Accept</http:fieldName>
        <http:headerName rdf:resource="https://www.w3.org/2008/http-header#accept"/>@@@TBD@@@
        <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="https://www.w3.org/2008/http-statusCodes#200"/>@@@TBD@@@
    <http:reasonPhrase>OK</http:reasonPhrase>
    <http:headers rdf:parseType="Collection">
      <http:MessageHeader>
        <http:fieldName>Date</http:fieldName>
        <http:headerName rdf:resource="https://www.w3.org/2008/http-header#date"/>@@@TBD@@@
        <http:fieldValue>.......</http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>Content-Type</http:fieldName>
        <http:headerName rdf:resource="https://www.w3.org/2008/http-header#content-type"/>@@@TBD@@@
        <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:XMLContent>
        <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="https://www.w3.org/2001/XMLSchema#anyURI">https://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd</cnt:systemId>
          </cnt:DocTypeDecl>
        </cnt:docTypeDecl>
        <cnt:xmlRest rdf:parseType="Literal"><html xmlns="https://www.w3.org/1999/xhtml" lang="en">
  <head>
    <title>My document</title>
  </head>
  <body>
    <p><!-- ...... --></p>
  </body>
</html></cnt:xmlRest>
      </cnt:XMLContent>
    </http:body>
  </http:Response>
  <http:Response rdf:ID="resp1">
    <http:httpVersion>1.1</http:httpVersion>
    <http:statusCodeNumber>200</http:statusCodeNumber>
    <http:statusCode rdf:resource="https://www.w3.org/2008/http-statusCodes#200"/>@@@TBD@@@
    <http:reasonPhrase>OK</http:reasonPhrase>
    <http:headers rdf:parseType="Collection">
      <http:MessageHeader>
        <http:fieldName>Date</http:fieldName>
        <http:headerName rdf:resource="https://www.w3.org/2008/http-header#date"/>@@@TBD@@@
        <http:fieldValue>.......</http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>Content-Type</http:fieldName>
        <http:headerName rdf:resource="https://www.w3.org/2008/http-header#content-type"/>@@@TBD@@@
        <http:fieldValue>image/png</http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>Vary</http:fieldName>
        <http:headerName rdf:resource="https://www.w3.org/2008/http-header#vary"/>@@@TBD@@@
        <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="https://www.w3.org/2001/XMLSchema#base64Binary">qouh3908t38hohfrf..........</cnt:bytes>
      </cnt:Base64Content>
    </http:body>
  </http:Response>
</rdf:RDF>

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

[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.

Appendix E: Document Changes

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

• split three RDF models for request methods, header names and status codes from the HTTP model to be updated separately from external registries
• changed the http:request property to http:requests
• introduced the http:Message class to be a base for the http:Request and http:Response class
• changed the http:version property to http:httpVersion
• added the dc:date property to the http:Message class
• introduced the http:methodName (with object literal), http:method (with object resource from external RDF model for header names) properties and the http:Method class instead of different http:Request sub-classes
• changed the multiple use of the http:header property to http:headers with an RDF collection
• changed the http:responseCode property to http:statusCode (with object literal from external RDF model for status codes), and introduced the literal http:statusCodeNumber and http:reasonPhrase properties
• changed the http:fieldName property to have a object literal
• introduced the http:headerName property having an object resource (from the external RDF model for header names)