HTTP Vocabulary in RDF

Abstract

The identification of resources on the Web by URI may not be sufficient to uniquely resolve a document 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 Evaluation and Report Language (EARL). This document describes a representation of HTTP vocabulary in RDF. The terms defined by this document allow HTTP headers that have been exchanged between a client and a server to be recorded in RDF format. The terms defined by this document includes vocabulary for HTTPS as well as other extensions to the core specification.

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 23 March Working Draft of the HTTP Vocabulary in RDF is an update of the previous HTTP Vocabulary in RDF Working Draft of 20 December 2006, and addressed the comments received since. In particular, this draft implements the decisions of the Working Group at its face to face meeting in February 2007 (see history of document changes). This document is expected to be published as a W3C Working Group Note after review and refinement.

The ERT 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 (QA IG), the W3C Semantic Web Interest Group (SWIG), the Protocol for Web Description Resources Working Group (POWDER WG), and the W3C Mobile Web Best Practices Working Group (BPWG) is particularly welcome.

Please send comments on this document by 20 April 2007 at the latest 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.

Table of Contents

1. Introduction
   • 1.1. Vocabulary Scope
   • 1.2. Namespaces
   • 1.3. Naming Conventions
   • 1.4. Use Cases
2. Basic HTTP 1.1 (RFC 2616)
   • 2.1. Connection Class
   • 2.2. Request Class
   • 2.3. Request URI Property
   • 2.4. Response Class
   • 2.5. Response Code Property
   • 2.6. Header Property
   • 2.7. Message Header Class
   • 2.8. Header Element Class
   • 2.9. Param Class
   • 2.10. Body Property
3. Header Name Class

Appendices

1. Schema in RDF/XML
   • A.1. HTTP Schema
   • A.2. HTTP-Header Schema
2. Security and Privacy
3. Vocabulary Terms
4. Practical Example
5. Document Changes
6. References

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 request and response messages in RDF format. For example by automated Web accessibility evaluation tools 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 1.4. Use Cases.

This document is not inteded to be a clarification of the different concepts of the HTTP specification. The HTTP specification is defined by a series of Request for Comments (RFC) and other documentation. These are listed in Appendix F. References. This document is also not intended to be an introduction to RDF, refer to [RDF] or [RDF-PRIMER] for this purpose.

1.1. Vocabulary Scope

The scope of this vocabulary is limited to providing a mechanism to record the HTTP request and response pairs exchanged between a client and a server. It is a representation of the HTTP interaction as observed over a network rather than the information that has been processed by client or a server. For example, the vocabulary does not provide a built-in mechanism to make statements about the validity of the exchanged messages or about the relationship between these exchanges. Such statements are often dependent on the application such as the user agent or server that is processing the HTTP messages.

1.2. Namespaces

The RDF representation of the HTTP vocabulary defined by this document uses the following namespaces:

1.3. 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 names for header name values are all-lower-case and use the same form as defined by the corresponding RFC documentation (e.g. accept-charset for the Accept-Charset header, or soapaction for the SoapAction extension header).

1.4. Use Cases

[Editor's Note: the Working Group is intending to elaborate and better describe the use cases listed below. The Working Group invites contribution and suggestions for further use cases.]

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

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 of the resource, especially those exchanged during content negotiation. RDF reporting languages like [EARL] can use this vocabulary to record these headers, for example POST parameters that were sent through a form and used by the server to generate a response.

Precising Conformance Claims

Conformance claims, for example conformance to the [WCAG], are sometimes only applicable to specific versions of a Web resource that is served at the same URI. For example a document that is served in multiple languages using language negotiation. The vocabulary presented by this document can be used to precise specific versions of Web resources for conformance claims.

Developing Web Applications

Web authoring tools, for example development tools for rich Web applications with dynamic content, can use this vocabulary to record the information exchanged between the client and the server in order to help developers debug scripts and applications. For example for developing AJAX applications where the Web resource is a composition of small sequences of contents.

2. Basic HTTP 1.1 (RFC 2616)

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

2.1 Connection Class

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

• http:connectionAuthority representing the connected authority (server host and port), and
• http:request representing an HTTP request.

<http:Connection rdf:ID="conn">
  <http:connectionAuthority>www.example.org:80</http:connectionAuthority>
  <http:request rdf:resource="#req0"/>
</http:Connection>

When the http:Connection class is used to record more than one request sent to a server, the order of these requests may be significant. For such cases, an RDF collection can be used as follows:

<http:Connection rdf:ID="conn2">
  <http:connectionAuthority>www.example.org:80</http:connectionAuthority>
  <http:request rdf:parseType="Collection">
    <http:Request rdf:about="#req0"/>
    <http:Request rdf:about="#req1"/>
  </http:request>
</http:Connection>

2.2. Request Class

The http:Request class represents an HTTP request. There are eight subclasses derived from the generic http:Request class, one for each request type defined in [RFC 2616]:

• http:OptionsRequest representing an HTTP Options request,
• http:GetRequest representing an HTTP Get request,
• http:HeadRequest representing an HTTP Head request,
• http:PostRequest representing an HTTP Post request,
• http:PutRequest representing an HTTP Put request,
• http:DeleteRequest representing an HTTP Delete request,
• http:TraceRequest representing an HTTP Trace request, and
• http:ConnectRequest representing an HTTP Connect request.

Note: additional types of requests can be created by subclassing the generic http:Request class.

The following properties may appear in http:Request resources:

• http:requestURI (or one of its sub-properties) representing the request URI (see also 2.3. Request URI Property),
• http:version representing the version of HTTP,
• http:header property (see 2.6. Header Property),
• http:body representing the message body (see 2.10. Body Property), and
• http:response pointing to the response resulting from this request (see 2.4. Response Class).

<http:GetRequest rdf:ID="req0">
  <http:abs_path>/</http:abs_path>
  <http:version>1.1</http:version>
  <http:header rdf:resource="#head1"/>
  <http:response rdf:resource="#resp0"/>
</http:GetRequest>

2.3. Request URI Property

The http: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:

• http:absoluteURI,
• http:abs_path, and
• http:authority.

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

<http:GetRequest>
  <http:absoluteURI>http://www.example.org:80/foo/bar</http:absoluteURI>
  ...
</http:GetRequest>

<http:GetRequest>
  <http:abs_path>/foo/bar</http:abs_path>
  ...
</http:GetRequest>

<ConnectRequest>
  <http:authority>www.example.org:80</http:authority>
  ...
</ConnectRequest>

2.4. Response Class

The http:Response class represents an HTTP response as defined in [RFC 2616]. The following properties may appear in nodes of type Response:

• http:version representing the version of HTTP used for the response,
• http:responseCode representing the response code sent by the server (see 2.5 Response Code Property),
• http:header property (see 2.6. Header Property),
• http:body representing the message body (see 2.10. Body Property).

<http:Response rdf:ID="resp0">
  <http:version>1.1</http:version>
  <http:responseCode rdf:resource="http://www.w3.org/2006/http#200"/>
  <http:header rdf:resource="#head2"/>
  <http:body rdf:parseType="Literal">
    <html xmlns="http://www.w3.org/1999/xhtml">
      <head>
      	<title>Hello World!</title>
      </head>
      <body>
        <p>Hello World!</p>
      </body>
    </html>
  </http:body>
</http:Response>

2.5 Response Code Property

The http:responseCode property represents the response code sent by the server. The object for this property can either be one of the pre-defined Values or a Literal in case a non-standard response code is sent.

<http:responseCode rdf:resource="http://www.w3.org/2006/http#200"/>

<http:responseCode>007</http:responseCode>

The RDF schema allows to define additional values by subclassing the class http:NewResponseCode.

2.6. Header Property

The http:header property represents an HTTP header and can be used in both http:Request and http:Response resources. The object of this property is of type http:MessageHeader (see 2.7 Message Header Class). A message header according to section 4.2 of [RFC 2616] consists of

1. a field name and
2. a field value.

The field name may consist of several header elements separated by a comma (see the JavaDoc for the org.apache.commons.httpclient.HeaderElement class in [HttpClient]). Each header element can be modelled as following:

1. an element name,
2. an element value, and
3. several parameters.

E.g. in the header Cache-Control: max-age=2000, the element name is max-age and the element value is 2000. In the header Content-Type: text/html; charset=utf-8, the element name is text/html and the parameter is charset=utf-8.

A parameter consists of

1. a parameter name, and
2. a parameter value.

So in the parameter charset=utf-8, the parameter name is charset and the parameter value is utf-8.

The components of a message header can be summarized like this:

message-header  = field-name ":" [ field-value ]
field-value     = [ header-element ] *( "," [ header-element ] )
header-element  = element-name [ "=" [ element-value ] ] *( ";" [ param ] )
param           = param-name [ "=" [ param-value ] ]

2.7 Message Header Class

The http:MessageHeader class represents a message header. It MUST have the following properties:

• http:fieldName representing a field name, the range of this property can either be a header name (for known headers, see 3. Header Name Class) or a Literal (for unknown or experimental headers);
• http:fieldValue representing a field value, the range of this property can either be a Literal (only for simple values, i.e. no comma-separated lists, no key-value pairs, and no parameters) or a (collection of) header elements (see 2.8 Header Element Class); the field values should be decomposed to the highest possible extent.

<http:MessageHeader>
  <http:fieldName rdf:resource="http://www.w3.org/2006/http-header#content-type"/>
  <http:fieldValue>application/xhtml+xml;charset=utf-8</http:fieldValue>
</http:MessageHeader>

<http:MessageHeader>
  <http:fieldName>x-foo</http:fieldName>
  <http:fieldValue>bar</http:fieldValue>
</http:MessageHeader>

2.8 Header Element Class

The http:HeaderElement class represents an element of a comma-separated list in a field value. It MUST have the following properties:

• one http:elementName property

It MAY have the following properties:

• one http:elementValue property;
• several http:param properties (see 2.9 Param Class).

<http:fieldValue>
  <http:HeaderElement>
    <http:elementName>application/xhtml+xml</http:elementName>
  </http:HeaderElement>
</http:fieldValue>

application/xhtml+xml

<http:fieldValue rdf:parseType="Collection">
  <http:HeaderElement>
    <http:elementName>application/xhtml+xml</http:elementName>
    <http:param>
      <http:Param>
        <http:paramName>q</http:paramName>
        <http:paramValue>1.0</http:paramValue>
      </http:Param>
    </http:param>
  </http:HeaderElement>
  <http:HeaderElement>
    <http:elementName>text/html</http:elementName>
    <http:param>
      <http:Param>
        <http:paramName>q</http:paramName>
        <http:paramValue>0.9</http:paramValue>
      </http:Param>
    </http:param>
  </http:HeaderElement>
</http:fieldValue>

application/xhtml+xml; q=1.0, text/html; q=0.9

<http:fieldValue>
  <http:HeaderElement>
    <http:elementName>max-age</http:elementName>
    <http:elementValue>2000</http:elementValue>
  </http:HeaderElement>
</http:fieldValue>

max-age=2000

2.9. Param Class

The http:Param class represents a parameter within a header element. It MUST have the following properties:

• one http:paramName property; and
• one http:paramValue property.

<http:HeaderElement>
  <http:elementName>application/xhtml+xml</http:elementName>
  <http:param>
    <http:Param>
      <http:paramName>charset</http:paramName>
      <http:paramValue>utf-8</http:paramValue>
    </http:Param>
  </http:param>
</http:HeaderElement>

application/xhtml+xml; charset=utf-8

2.10. Body Property

The http:body property represents an HTTP entity body as defined in [RFC 2616]. It can appear in nodes of both type http:Request or http:Response. HTTP bodies are series of bytes. You must use the following algorithm:

Is the resource a text resource?

• No: use a base64 data URI (see [RFC 2397]).
• Yes: Is a character encoding specified?
  • Yes: use the specified character encoding.
  • No: use the RDF document character encoding.

  Is it possible to decode the byte sequence?

  • No: use a base64 data URI (see [RFC 2397]).
  • Yes: is the resource content wellformed XML?
    • Yes: use rdf:parseType="Literal".
    • No: use plain literal (CDATA for RDF/XML serialization).

    Escape special characters.

    Is the resulting literal safe to use within the RDF?

    • No: use a base64 data URI (see [RFC 2397]).
    • Yes: create a literal.

<http:body rdf:resource="data:base64,aksgbq3833o3gbo4zgblakc8t9ut2">

<http:body rdf:parseType="Literal">
  <foo>
    <bar>blah</bar>
  </foo>
</http:body>

<http:body><![CDATA[<head>
  <meta name="keywords" content="foo, bar">
</head>]]></http:body>

Appendix A: Schema in RDF/XML

Editor's Note: the working group is looking for feedback and comments on the schema defined below, for example on the hierarchy of the classes or the restrictions on the properties.

Appendix A.1: HTTP Schema

<?xml version="1.0" encoding="utf-8"?>
<rdf:RDF
   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
   xmlns:owl="http://www.w3.org/2002/07/owl#">

<rdf:Description rdf:about="http://www.w3.org/2006/http#">
 <rdfs:comment xml:lang="en">A namespace for describing HTTP messages
   (http://www.w3.org/Protocols/rfc2616/rfc2616.html)</rdfs:comment>
</rdf:Description>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#Connection">
  <rdfs:label xml:lang="en">Connection</rdfs:label>
  <rdfs:comment xml:lang="en">An HTTP connection</rdfs:comment>
  <rdfs:subClassOf rdf:parseType="Collection">
    <owl:Restriction>
      <owl:onProperty rdf:resource="http://www.w3.org/2006/http#connectionAuthority"/>
      <owl:minCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger">1</owl:minCardinality>
      <owl:maxCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger">1</owl:maxCardinality>
    </owl:Restriction>
  </rdfs:subClassOf>
</rdfs:Class>

<rdf:Property rdf:about="http://www.w3.org/2006/http#connectionAuthority">
  <rdfs:label xml:lang="en">Connection authority</rdfs:label>
  <rdfs:comment xml:lang="en">An HTTP Connection authority</rdfs:comment>
  <rdfs:domain rdf:resource="http://www.w3.org/2006/http#Connection"/>
</rdf:Property>

<rdf:Property rdf:about="http://www.w3.org/2006/http#request">
  <rdfs:label xml:lang="en">Request</rdfs:label>
  <rdfs:comment xml:lang="en">Has an HTTP request</rdfs:comment>
  <rdfs:domain rdf:resource="http://www.w3.org/2006/http#Connection"/>
  <rdfs:range rdf:resource="http://www.w3.org/2006/http#Request"/>
</rdf:Property>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#Request">
  <rdfs:label xml:lang="en">Request</rdfs:label>
  <rdfs:comment xml:lang="en">An HTTP request</rdfs:comment>
</rdfs:Class>

<!-- request methods start -->
<rdfs:Class rdf:about="http://www.w3.org/2006/http#OptionsRequest">
  <rdfs:label xml:lang="en">Options</rdfs:label>
  <rdfs:comment xml:lang="en">The OPTIONS request</rdfs:comment>
  <rdfs:subClassOf rdf:resource="http://www.w3.org/2006/http#Request"/>
</rdfs:Class>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#GetRequest">
  <rdfs:label xml:lang="en">Get</rdfs:label>
  <rdfs:comment xml:lang="en">The GET request</rdfs:comment>
  <rdfs:subClassOf rdf:resource="http://www.w3.org/2006/http#Request"/>
</rdfs:Class>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#HeadRequest">
  <rdfs:label xml:lang="en">Head</rdfs:label>
  <rdfs:comment xml:lang="en">The HEAD request</rdfs:comment>
  <rdfs:subClassOf rdf:resource="http://www.w3.org/2006/http#Request"/>
</rdfs:Class>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#PostRequest">
  <rdfs:label xml:lang="en">Post</rdfs:label>
  <rdfs:comment xml:lang="en">The POST request</rdfs:comment>
  <rdfs:subClassOf rdf:resource="http://www.w3.org/2006/http#Request"/>
</rdfs:Class>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#PutRequest">
  <rdfs:label xml:lang="en">Put</rdfs:label>
  <rdfs:comment xml:lang="en">The PUT request</rdfs:comment>
  <rdfs:subClassOf rdf:resource="http://www.w3.org/2006/http#Request"/>
</rdfs:Class>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#DeleteRequest">
  <rdfs:label xml:lang="en">Delete</rdfs:label>
  <rdfs:comment xml:lang="en">The DELETE request</rdfs:comment>
  <rdfs:subClassOf rdf:resource="http://www.w3.org/2006/http#Request"/>
</rdfs:Class>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#TraceRequest">
  <rdfs:label xml:lang="en">Trace</rdfs:label>
  <rdfs:comment xml:lang="en">The TRACE request</rdfs:comment>
  <rdfs:subClassOf rdf:resource="http://www.w3.org/2006/http#Request"/>
</rdfs:Class>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#ConnectRequest">
  <rdfs:label xml:lang="en">Connect</rdfs:label>
  <rdfs:comment xml:lang="en">The CONNECT request</rdfs:comment>
  <rdfs:subClassOf rdf:resource="http://www.w3.org/2006/http#Request"/>
</rdfs:Class>
<!-- request methods end -->

<rdf:Property rdf:about="http://www.w3.org/2006/http#requestURI">
  <rdfs:label xml:lang="en">Request URI</rdfs:label>
  <rdfs:comment xml:lang="en">Has an HTTP request URI</rdfs:comment>
  <rdfs:domain rdf:resource="http://www.w3.org/2006/http#Request"/>
  <rdfs:range rdf:resource="http://www.w3.org/2006/http#RequestURI"/>
</rdf:Property>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#RequestURI">
  <rdfs:label xml:lang="en">Request URI</rdfs:label>
  <rdfs:comment xml:lang="en">The HTTP request URI</rdfs:comment>
  <owl:oneOf rdf:parseType="Collection">
    <owl:Thing rdf:about="http://www.w3.org/2006/http#asterisk">
      <rdfs:label xml:lang="en">Asterisk</rdfs:label>
      <rdfs:comment xml:lang="en">An asterisk used as request URI</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2000/01/rdf-schema#Literal"/>
  </owl:oneOf>
</rdfs:Class>

<rdf:Property rdf:about="http://www.w3.org/2006/http#absoluteURI">
  <rdfs:label xml:lang="en">Absolute request URI</rdfs:label>
  <rdfs:comment xml:lang="en">An absolute request URI</rdfs:comment>
  <rdfs:subPropertyOf rdf:resource="http://www.w3.org/2006/http#requestURI"/>
</rdf:Property>

<rdf:Property rdf:about="http://www.w3.org/2006/http#abs_path">
  <rdfs:label xml:lang="en">Absolute path</rdfs:label>
  <rdfs:comment xml:lang="en">An absolute path used as request URI</rdfs:comment>
  <rdfs:subPropertyOf rdf:resource="http://www.w3.org/2006/http#requestURI"/>
</rdf:Property>

<rdf:Property rdf:about="http://www.w3.org/2006/http#authority">
  <rdfs:label xml:lang="en">Authority</rdfs:label>
  <rdfs:comment xml:lang="en">An authority used as request URI</rdfs:comment>
  <rdfs:subPropertyOf rdf:resource="http://www.w3.org/2006/http#requestURI"/>
</rdf:Property>

<rdf:Property rdf:about="http://www.w3.org/2006/http#response">
  <rdfs:label xml:lang="en">Response</rdfs:label>
  <rdfs:comment xml:lang="en">Has an HTTP response</rdfs:comment>
  <rdfs:domain rdf:resource="http://www.w3.org/2006/http#Request"/>
  <rdfs:range rdf:resource="http://www.w3.org/2006/http#Response"/>
</rdf:Property>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#Response">
  <rdfs:label xml:lang="en">Response</rdfs:label>
  <rdfs:comment xml:lang="en">The HTTP Response</rdfs:comment>
</rdfs:Class>

<rdf:Property rdf:about="http://www.w3.org/2006/http#responseCode">
  <rdfs:label xml:lang="en">Response code</rdfs:label>
  <rdfs:comment xml:lang="en">Has an HTTP response code</rdfs:comment>
  <rdfs:domain rdf:resource="http://www.w3.org/2006/http#Response"/>
  <rdfs:range>
    <owl:Class>
      <owl:unionOf rdf:parseType="Collection">
        <owl:Class rdf:about="http://www.w3.org/2006/http#ResponseCode"/>
        <owl:Class rdf:about="http://www.w3.org/2001/XMLSchema#positiveInteger"/>
      </owl:unionOf>
    </owl:Class>
  </rdfs:range>
</rdf:Property>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#ResponseCode">
  <rdfs:label xml:lang="en">Response code</rdfs:label>
  <rdfs:comment xml:lang="en">The HTTP Response Code</rdfs:comment>
  <owl:oneOf rdf:parseType="Collection">
    <owl:Thing rdf:about="http://www.w3.org/2006/http#100">
      <rdfs:label xml:lang="en">Continue</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#101">
      <rdfs:label xml:lang="en">Switching Protocols</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#200">
      <rdfs:label xml:lang="en">OK</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#201">
      <rdfs:label xml:lang="en">Created</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#202">
      <rdfs:label xml:lang="en">Accepted</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#203">
      <rdfs:label xml:lang="en">Non-Authoritative Information</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#204">
      <rdfs:label xml:lang="en">No Content</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#205">
      <rdfs:label xml:lang="en">Reset Content</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#206">
      <rdfs:label xml:lang="en">Partial Content</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#300">
      <rdfs:label xml:lang="en">Multiple Choices</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#301">
      <rdfs:label xml:lang="en">Moved Permanently</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#302">
      <rdfs:label xml:lang="en">Found</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#303">
      <rdfs:label xml:lang="en">See Other</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#304">
      <rdfs:label xml:lang="en">Not Modified</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#305">
      <rdfs:label xml:lang="en">Use Proxy</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#306">
      <rdfs:label xml:lang="en">(Unused)</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#307">
      <rdfs:label xml:lang="en">Temporary Redirect</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#400">
      <rdfs:label xml:lang="en">Bad Request</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#401">
      <rdfs:label xml:lang="en">Unauthorized</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#402">
      <rdfs:label xml:lang="en">Payment Required</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#403">
      <rdfs:label xml:lang="en">Forbidden</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#404">
      <rdfs:label xml:lang="en">Not Found</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#405">
      <rdfs:label xml:lang="en">Method Not Allowed</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#406">
      <rdfs:label xml:lang="en">Not Acceptable</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#407">
      <rdfs:label xml:lang="en">Proxy Authentication Required</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#408">
      <rdfs:label xml:lang="en">Request Timeout</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#409">
      <rdfs:label xml:lang="en">Conflict</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#410">
      <rdfs:label xml:lang="en">Gone</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#411">
      <rdfs:label xml:lang="en">Length Required</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#412">
      <rdfs:label xml:lang="en">Precondition Failed</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#413">
      <rdfs:label xml:lang="en">Request Entity Too Large</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#414">
      <rdfs:label xml:lang="en">Request-URI Too Long</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#415">
      <rdfs:label xml:lang="en">Unsupported Media Type</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#416">
      <rdfs:label xml:lang="en">Requested Range Not Satisfiable</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#417">
      <rdfs:label xml:lang="en">Expectation Failed</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#500">
      <rdfs:label xml:lang="en">Internal Server Error</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#501">
      <rdfs:label xml:lang="en">Not Implemented</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#502">
      <rdfs:label xml:lang="en">Bad Gateway</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#503">
      <rdfs:label xml:lang="en">Service Unavailable</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#504">
      <rdfs:label xml:lang="en">Gateway Timeout</rdfs:label>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http#505">
      <rdfs:label xml:lang="en">HTTP Version Not Supported</rdfs:label>
    </owl:Thing>
    <!-- new response code, stub for subclassing -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http#NewResponseCode"/>
  </owl:oneOf>
</rdfs:Class>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#NewResponseCode">
  <rdfs:label xml:lang="en">New Response Code</rdfs:label>
  <rdfs:comment xml:lang="en">New HTTP Response Code. If you want to define new header names, subclass this stub.</rdfs:comment>
</rdfs:Class>

<rdf:Property rdf:about="http://www.w3.org/2006/http#header">
  <rdfs:label xml:lang="en">Header</rdfs:label>
  <rdfs:comment xml:lang="en">Has a header</rdfs:comment>
  <rdfs:range rdf:resource="http://www.w3.org/2006/http#MessageHeader"/>
</rdf:Property>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#MessageHeader">
  <rdfs:label xml:lang="en">Message header</rdfs:label>
  <rdfs:comment xml:lang="en">A message header according to section 4.2 of HTTP 1.1</rdfs:comment>
  <rdfs:subClassOf rdf:parseType="Collection">
    <owl:Restriction>
      <owl:onProperty rdf:resource="http://www.w3.org/2006/http#fieldName"/>
      <owl:minCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger">1</owl:minCardinality>
      <owl:maxCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger">1</owl:maxCardinality>
    </owl:Restriction>
    <owl:Restriction>
      <owl:onProperty rdf:resource="http://www.w3.org/2006/http#fieldValue"/>
      <owl:minCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger">1</owl:minCardinality>
      <owl:maxCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger">1</owl:maxCardinality>
    </owl:Restriction>
  </rdfs:subClassOf>
</rdfs:Class>

<rdf:Property rdf:about="http://www.w3.org/2006/http#fieldName">
  <rdfs:label xml:lang="en">Field name</rdfs:label>
  <rdfs:comment xml:lang="en">Has a field name</rdfs:comment>
  <rdfs:domain rdf:resource="http://www.w3.org/2006/http#MessageHeader"/>
  <rdfs:range>
    <rdfs:Class>
      <owl:unionOf rdf:parseType="Collection">
        <owl:Class rdf:about="http://www.w3.org/2006/http#HeaderName"/>
        <owl:Class rdf:about="http://www.w3.org/2000/01/rdf-schema#Literal"/>
      </owl:unionOf>
    </rdfs:Class>
  </rdfs:range>
</rdf:Property>

<rdf:Property rdf:about="http://www.w3.org/2006/http#fieldValue">
  <rdfs:label xml:lang="en">Field value</rdfs:label>
  <rdfs:comment xml:lang="en">Has a field value</rdfs:comment>
  <rdfs:domain rdf:resource="http://www.w3.org/2006/http#MessageHeader"/>
</rdf:Property>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#HeaderElement">
  <rdfs:label xml:lang="en">Header element</rdfs:label>
  <rdfs:comment xml:lang="en">An element of a comma-separated list in a field value</rdfs:comment>
  <rdfs:subClassOf rdf:parseType="Collection">
    <owl:Restriction>
      <owl:onProperty rdf:resource="http://www.w3.org/2006/http#elementName"/>
      <owl:minCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger">1</owl:minCardinality>
      <owl:maxCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger">1</owl:maxCardinality>
    </owl:Restriction>
    <owl:Restriction>
      <owl:onProperty rdf:resource="http://www.w3.org/2006/http#elementValue"/>
      <owl:minCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger">0</owl:minCardinality>
      <owl:maxCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger">1</owl:maxCardinality>
    </owl:Restriction>
  </rdfs:subClassOf>
</rdfs:Class>

<rdf:Property rdf:about="http://www.w3.org/2006/http#elementName">
  <rdfs:label xml:lang="en">Element name</rdfs:label>
  <rdfs:comment xml:lang="en">Has an element name</rdfs:comment>
  <rdfs:domain rdf:resource="http://www.w3.org/2006/http#HeaderElement"/>
  <rdfs:range rdf:resource="http://www.w3.org/2000/01/rdf-schema#Literal"/>
</rdf:Property>

<rdf:Property rdf:about="http://www.w3.org/2006/http#elementValue">
  <rdfs:label xml:lang="en">Element value</rdfs:label>
  <rdfs:comment xml:lang="en">Has an element value</rdfs:comment>
  <rdfs:domain rdf:resource="http://www.w3.org/2006/http#HeaderElement"/>
  <rdfs:range rdf:resource="http://www.w3.org/2000/01/rdf-schema#Literal"/>
</rdf:Property>

<rdf:Property rdf:about="http://www.w3.org/2006/http#param">
  <rdfs:label xml:lang="en">Parameter</rdfs:label>
  <rdfs:comment xml:lang="en">Has a parameter</rdfs:comment>
  <rdfs:domain rdf:resource="http://www.w3.org/2006/http#HeaderElement"/>
  <rdfs:range rdf:resource="http://www.w3.org/2006/http#Param"/>
</rdf:Property>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#Param">
  <rdfs:label xml:lang="en">Parameter</rdfs:label>
  <rdfs:comment xml:lang="en">A parameter for a header element</rdfs:comment>
  <rdfs:subClassOf rdf:parseType="Collection">
    <owl:Restriction>
      <owl:onProperty rdf:resource="http://www.w3.org/2006/http#paramName"/>
      <owl:minCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger">1</owl:minCardinality>
      <owl:maxCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger">1</owl:maxCardinality>
    </owl:Restriction>
    <owl:Restriction>
      <owl:onProperty rdf:resource="http://www.w3.org/2006/http#paramValue"/>
      <owl:minCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger">1</owl:minCardinality>
      <owl:maxCardinality rdf:datatype="http://www.w3.org/2001/XMLSchema#nonNegativeInteger">1</owl:maxCardinality>
    </owl:Restriction>
  </rdfs:subClassOf>
</rdfs:Class>

<rdf:Property rdf:about="http://www.w3.org/2006/http#paramName">
  <rdfs:label xml:lang="en">Parameter name</rdfs:label>
  <rdfs:comment xml:lang="en">Has a parameter name</rdfs:comment>
  <rdfs:domain rdf:resource="http://www.w3.org/2006/http#Param"/>
  <rdfs:range rdf:resource="http://www.w3.org/2000/01/rdf-schema#Literal"/>
</rdf:Property>

<rdf:Property rdf:about="http://www.w3.org/2006/http#paramValue">
  <rdfs:label xml:lang="en">Parameter value</rdfs:label>
  <rdfs:comment xml:lang="en">Has a parameter value</rdfs:comment>
  <rdfs:domain rdf:resource="http://www.w3.org/2006/http#Param"/>
  <rdfs:range rdf:resource="http://www.w3.org/2000/01/rdf-schema#Literal"/>
</rdf:Property>

<rdf:Property rdf:about="http://www.w3.org/2006/http#version">
  <rdfs:label xml:lang="en">Version</rdfs:label>
  <rdfs:comment xml:lang="en">The HTTP version</rdfs:comment>
</rdf:Property>

<rdf:Property rdf:about="http://www.w3.org/2006/http#body">
  <rdfs:label xml:lang="en">Entity body</rdfs:label>
  <rdfs:comment xml:lang="en">The HTTP entity body</rdfs:comment>
</rdf:Property>

</rdf:RDF>

Appendix A.2: HTTP-Header Schema

<?xml version="1.0" encoding="utf-8"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
         xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
         xmlns:owl="http://www.w3.org/2002/07/owl#">

<rdf:Description rdf:about="http://www.w3.org/2006/http-header#">
 <rdfs:comment xml:lang="en">A namespace for describing HTTP header names.</rdfs:comment>
</rdf:Description>

<rdfs:Class rdf:about="http://www.w3.org/2006/http#HeaderName">
  <rdfs:label xml:lang="en">Header name</rdfs:label>
  <rdfs:comment xml:lang="en">A header name defined in HTTP 1.1</rdfs:comment>
  <owl:oneOf rdf:parseType="Collection">
    <!-- HTTP 1.1 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#accept">
      <rdfs:label xml:lang="en">Accept</rdfs:label>
      <rdfs:comment xml:lang="en">The Accept header (see RFC 2616, section 14.1)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#accept-charset">
      <rdfs:label xml:lang="en">Accept-Charset</rdfs:label>
      <rdfs:comment xml:lang="en">The Accept-Charset header (see RFC 2616, section 14.2)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#accept-encoding">
      <rdfs:label xml:lang="en">Accept-Encoding</rdfs:label>
      <rdfs:comment xml:lang="en">The Accept-Encoding header (see RFC 2616, section 14.3)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#accept-language">
      <rdfs:label xml:lang="en">Accept-Language</rdfs:label>
      <rdfs:comment xml:lang="en">The Accept-Language header (see RFC 2616, section 14.4)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#accept-ranges">
      <rdfs:label xml:lang="en">Accept-Ranges</rdfs:label>
      <rdfs:comment xml:lang="en">The Accept-Ranges header (see RFC 2616, section 14.5)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#age">
      <rdfs:label xml:lang="en">Age</rdfs:label>
      <rdfs:comment xml:lang="en">The Age header (see RFC 2616, section 14.6)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#allow">
      <rdfs:label xml:lang="en">Allow</rdfs:label>
      <rdfs:comment xml:lang="en">The Allow header (see RFC 2616, section 14.7)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#authorization">
      <rdfs:label xml:lang="en">Authorization</rdfs:label>
      <rdfs:comment xml:lang="en">The Authorization header (see RFC 2616, section 14.8)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#cache-control">
      <rdfs:label xml:lang="en">Cache-Control</rdfs:label>
      <rdfs:comment xml:lang="en">The Cache-Control header (see RFC 2616, section 14.9)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#connection">
      <rdfs:label xml:lang="en">Connection</rdfs:label>
      <rdfs:comment xml:lang="en">The Connection header (see RFC 2616, section 14.10)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#content-encoding">
      <rdfs:label xml:lang="en">Content-Encoding</rdfs:label>
      <rdfs:comment xml:lang="en">The Content-Encoding header (see RFC 2616, section 14.11)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#content-language">
      <rdfs:label xml:lang="en">Content-Language</rdfs:label>
      <rdfs:comment xml:lang="en">The Content-Language header (see RFC 2616, section 14.12)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#content-length">
      <rdfs:label xml:lang="en">Content-Length</rdfs:label>
      <rdfs:comment xml:lang="en">The Content-Length header (see RFC 2616, section 14.13)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#content-location">
      <rdfs:label xml:lang="en">Content-Location</rdfs:label>
      <rdfs:comment xml:lang="en">The Content-Location header (see RFC 2616, section 14.14)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#content-md5">
      <rdfs:label xml:lang="en">Content-MD5</rdfs:label>
      <rdfs:comment xml:lang="en">The Content-MD5 header (see RFC 2616, section 14.15)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#content-range">
      <rdfs:label xml:lang="en">Content-Range</rdfs:label>
      <rdfs:comment xml:lang="en">The Content-Range header (see RFC 2616, section 14.16)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#content-type">
      <rdfs:label xml:lang="en">Content-Type</rdfs:label>
      <rdfs:comment xml:lang="en">The Content-Type header (see RFC 2616, section 14.17)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#date">
      <rdfs:label xml:lang="en">Date</rdfs:label>
      <rdfs:comment xml:lang="en">The Date header (see RFC 2616, section 14.18)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#etag">
      <rdfs:label xml:lang="en">ETag</rdfs:label>
      <rdfs:comment xml:lang="en">The ETag header (see RFC 2616, section 14.19)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#expect">
      <rdfs:label xml:lang="en">Expect</rdfs:label>
      <rdfs:comment xml:lang="en">The Expect header (see RFC 2616, section 14.20)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#expires">
      <rdfs:label xml:lang="en">Expires</rdfs:label>
      <rdfs:comment xml:lang="en">The Expires header (see RFC 2616, section 14.21)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#from">
      <rdfs:label xml:lang="en">From</rdfs:label>
      <rdfs:comment xml:lang="en">The From header (see RFC 2616, section 14.22)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#host">
      <rdfs:label xml:lang="en">Host</rdfs:label>
      <rdfs:comment xml:lang="en">The Host header (see RFC 2616, section 14.23)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#if-match">
      <rdfs:label xml:lang="en">If-Match</rdfs:label>
      <rdfs:comment xml:lang="en">The If-Match header (see RFC 2616, section 14.24)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#if-modified-since">
      <rdfs:label xml:lang="en">If-Modified-Since</rdfs:label>
      <rdfs:comment xml:lang="en">The If-Modified-Since header (see RFC 2616, section 14.25)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#if-none-match">
      <rdfs:label xml:lang="en">If-None-Match</rdfs:label>
      <rdfs:comment xml:lang="en">The If-None-Match header (see RFC 2616, section 14.26)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#if-range">
      <rdfs:label xml:lang="en">If-Range</rdfs:label>
      <rdfs:comment xml:lang="en">The If-Range header (see RFC 2616, section 14.27)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#if-unmodified-since">
      <rdfs:label xml:lang="en">If-Unmodified-Since</rdfs:label>
      <rdfs:comment xml:lang="en">The If-Unmodified-Since header (see RFC 2616, section 14.28)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#last-modified">
      <rdfs:label xml:lang="en">Last-Modified</rdfs:label>
      <rdfs:comment xml:lang="en">The Last-Modified header (see RFC 2616, section 14.29)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#location">
      <rdfs:label xml:lang="en">Location</rdfs:label>
      <rdfs:comment xml:lang="en">The Location header (see RFC 2616, section 14.30)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#max-forwards">
      <rdfs:label xml:lang="en">Max-Forwards</rdfs:label>
      <rdfs:comment xml:lang="en">The Max-Forwards header (see RFC 2616, section 14.31)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#mime-version">
      <rdfs:label xml:lang="en">MIME-Version</rdfs:label>
      <rdfs:comment xml:lang="en">The MIME-Version header (see RFC 2616, section 19.4.1)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#pragma">
      <rdfs:label xml:lang="en">Pragma</rdfs:label>
      <rdfs:comment xml:lang="en">The Pragma header (see RFC 2616, section 14.32)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#proxy-authenticate">
      <rdfs:label xml:lang="en">Proxy-Authenticate</rdfs:label>
      <rdfs:comment xml:lang="en">The Proxy-Authenticate header (see RFC 2616, section 14.33)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#proxy-authorization">
      <rdfs:label xml:lang="en">Proxy-Authorization</rdfs:label>
      <rdfs:comment xml:lang="en">The Proxy-Authorization header (see RFC 2616, section 14.34)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#range">
      <rdfs:label xml:lang="en">Range</rdfs:label>
      <rdfs:comment xml:lang="en">The Range header (see RFC 2616, section 14.35)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#referer">
      <rdfs:label xml:lang="en">Referer</rdfs:label>
      <rdfs:comment xml:lang="en">The Referer header (see RFC 2616, section 14.36)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#retry-after">
      <rdfs:label xml:lang="en">Retry-After</rdfs:label>
      <rdfs:comment xml:lang="en">The Retry-After header (see RFC 2616, section 14.37)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#server">
      <rdfs:label xml:lang="en">Server</rdfs:label>
      <rdfs:comment xml:lang="en">The Server header (see RFC 2616, section 14.38)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#te">
      <rdfs:label xml:lang="en">TE</rdfs:label>
      <rdfs:comment xml:lang="en">The TE header (see RFC 2616, section 14.39)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#trailer">
      <rdfs:label xml:lang="en">Trailer</rdfs:label>
      <rdfs:comment xml:lang="en">The Trailer header (see RFC 2616, section 14.40)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#transfer-encoding">
      <rdfs:label xml:lang="en">Transfer-Encoding</rdfs:label>
      <rdfs:comment xml:lang="en">The Transfer-Encoding header (see RFC 2616, section 14.41)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#upgrade">
      <rdfs:label xml:lang="en">Upgrade</rdfs:label>
      <rdfs:comment xml:lang="en">The Upgrade header (see RFC 2616, section 14.42)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#user-agent">
      <rdfs:label xml:lang="en">User-Agent</rdfs:label>
      <rdfs:comment xml:lang="en">The User-Agent header (see RFC 2616, section 14.43)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#vary">
      <rdfs:label xml:lang="en">Vary</rdfs:label>
      <rdfs:comment xml:lang="en">The Vary header (see RFC 2616, section 14.44)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#via">
      <rdfs:label xml:lang="en">Via</rdfs:label>
      <rdfs:comment xml:lang="en">The Via header (see RFC 2616, section 14.45)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#warning">
      <rdfs:label xml:lang="en">Warning</rdfs:label>
      <rdfs:comment xml:lang="en">The Warning header (see RFC 2616, section 14.46)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#www-authenticate">
      <rdfs:label xml:lang="en">WWW-Authenticate</rdfs:label>
      <rdfs:comment xml:lang="en">The WWW-Authenticate header (see RFC 2616, section 14.47)</rdfs:comment>
    </owl:Thing>
    <!-- HTTP 1.1 headers end -->

    <!-- RFC2068 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#content-base">
      <rdfs:label xml:lang="en">Content-Base</rdfs:label>
      <rdfs:comment xml:lang="en">The Content-Base header (see RFC 2068, section 14.11)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#content-version">
      <rdfs:label xml:lang="en">Content-Version</rdfs:label>
      <rdfs:comment xml:lang="en">The Content-Version header (see RFC 2068, section 19.6.2.2)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#derived-from">
      <rdfs:label xml:lang="en">Derived-From</rdfs:label>
      <rdfs:comment xml:lang="en">The Derived-From header (see RFC 2068, section 19.6.2.3</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#link">
      <rdfs:label xml:lang="en">Link</rdfs:label>
      <rdfs:comment xml:lang="en">The Link header (see RFC 2068, section 19.6.2.4)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#public">
      <rdfs:label xml:lang="en">Public</rdfs:label>
      <rdfs:comment xml:lang="en">The Public header (see RFC 2068, section 14.35)</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#uri">
      <rdfs:label xml:lang="en">URI</rdfs:label>
      <rdfs:comment xml:lang="en">The URI header (see RFC 2068, section 19.6.2.5)</rdfs:comment>
    </owl:Thing>
    <!-- RFC2068 headers end -->

    <!-- RFC2109 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#set-cookie">
      <rdfs:label xml:lang="en">Set-Cookie</rdfs:label>
      <rdfs:comment xml:lang="en">The Set-Cookie header</rdfs:comment>
    </owl:Thing>
    <!-- RFC2109 headers end -->

    <!-- RFC2227 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#meter">
      <rdfs:label xml:lang="en">Meter</rdfs:label>
      <rdfs:comment xml:lang="en">The Meter header</rdfs:comment>
    </owl:Thing>
    <!-- RFC2227 headers end -->

    <!-- RFC2295 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#accept-features">
      <rdfs:label xml:lang="en">Accept-Features</rdfs:label>
      <rdfs:comment xml:lang="en">The Accept-Features header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#alternates">
      <rdfs:label xml:lang="en">Alternates</rdfs:label>
      <rdfs:comment xml:lang="en">The Alternates header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#negotiate">
      <rdfs:label xml:lang="en">Negotiate</rdfs:label>
      <rdfs:comment xml:lang="en">The Negotiate header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#tcn">
      <rdfs:label xml:lang="en">TCN</rdfs:label>
      <rdfs:comment xml:lang="en">The TCN header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#variant-vary">
      <rdfs:label xml:lang="en">Variant-Vary</rdfs:label>
      <rdfs:comment xml:lang="en">The Variant-Vary header</rdfs:comment>
    </owl:Thing>
    <!-- RFC2295 headers end -->

    <!-- RFC2310 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#safe">
      <rdfs:label xml:lang="en">Safe</rdfs:label>
      <rdfs:comment xml:lang="en">The Safe header</rdfs:comment>
    </owl:Thing>
    <!-- RFC2310 headers end -->

    <!-- RFC2324 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#accept-additions">
      <rdfs:label xml:lang="en">Accept-Additions</rdfs:label>
      <rdfs:comment xml:lang="en">The Accept-Additions header</rdfs:comment>
    </owl:Thing>
    <!-- RFC2324 headers end -->

    <!-- RFC2518 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#dav">
      <rdfs:label xml:lang="en">DAV</rdfs:label>
      <rdfs:comment xml:lang="en">The DAV header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#depth">
      <rdfs:label xml:lang="en">Depth</rdfs:label>
      <rdfs:comment xml:lang="en">The Depth header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#destination">
      <rdfs:label xml:lang="en">Destination</rdfs:label>
      <rdfs:comment xml:lang="en">The Destination header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#if">
      <rdfs:label xml:lang="en">If</rdfs:label>
      <rdfs:comment xml:lang="en">The If header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#lock-token">
      <rdfs:label xml:lang="en">Lock-Token</rdfs:label>
      <rdfs:comment xml:lang="en">The Lock-Token header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#overwrite">
      <rdfs:label xml:lang="en">Overwrite</rdfs:label>
      <rdfs:comment xml:lang="en">The Overwrite header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#status-uri">
      <rdfs:label xml:lang="en">Status-URI</rdfs:label>
      <rdfs:comment xml:lang="en">The Status-URI header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#timeout">
      <rdfs:label xml:lang="en">Timeout</rdfs:label>
      <rdfs:comment xml:lang="en">The Timeout header</rdfs:comment>
    </owl:Thing>
    <!-- RFC2518 headers end -->

    <!-- RFC2617 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#authentication-info">
      <rdfs:label xml:lang="en">Authentication-Info</rdfs:label>
      <rdfs:comment xml:lang="en">The Authentication-Info header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#proxy-authentication-info">
      <rdfs:label xml:lang="en">Proxy-Authentication-Info</rdfs:label>
      <rdfs:comment xml:lang="en">The Proxy-Authentication-Info header</rdfs:comment>
    </owl:Thing>
    <!-- RFC2617 headers end -->

    <!-- RFC2660 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#security-scheme">
      <rdfs:label xml:lang="en">Security-Scheme</rdfs:label>
      <rdfs:comment xml:lang="en">The Security-Scheme header</rdfs:comment>
    </owl:Thing>
    <!-- RFC2660 headers end -->

    <!-- RFC2774 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#c-ext">
      <rdfs:label xml:lang="en">C-Ext</rdfs:label>
      <rdfs:comment xml:lang="en">The C-Ext header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#c-man">
      <rdfs:label xml:lang="en">C-Man</rdfs:label>
      <rdfs:comment xml:lang="en">The C-Man header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#c-opt">
      <rdfs:label xml:lang="en">C-Opt</rdfs:label>
      <rdfs:comment xml:lang="en">The C-Opt header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#ext">
      <rdfs:label xml:lang="en">Ext</rdfs:label>
      <rdfs:comment xml:lang="en">The Ext header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#man">
      <rdfs:label xml:lang="en">Man</rdfs:label>
      <rdfs:comment xml:lang="en">The Man header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#opt">
      <rdfs:label xml:lang="en">Opt</rdfs:label>
      <rdfs:comment xml:lang="en">The Opt header</rdfs:comment>
    </owl:Thing>
    <!-- RFC2774 headers end -->

    <!-- RFC2965 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#cookie">
      <rdfs:label xml:lang="en">Cookie</rdfs:label>
      <rdfs:comment xml:lang="en">The Cookie header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#cookie2">
      <rdfs:label xml:lang="en">Cookie2</rdfs:label>
      <rdfs:comment xml:lang="en">The Cookie2 header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#set-cookie2">
      <rdfs:label xml:lang="en">Set-Cookie2</rdfs:label>
      <rdfs:comment xml:lang="en">The Set-Cookie2 header</rdfs:comment>
    </owl:Thing>
    <!-- RFC2965 headers end -->

    <!-- RFC3229 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#a-im">
      <rdfs:label xml:lang="en">A-IM</rdfs:label>
      <rdfs:comment xml:lang="en">The A-IM header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#delta-base">
      <rdfs:label xml:lang="en">Delta-Base</rdfs:label>
      <rdfs:comment xml:lang="en">The Delta-Base header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#im">
      <rdfs:label xml:lang="en">IM</rdfs:label>
      <rdfs:comment xml:lang="en">The IM header</rdfs:comment>
    </owl:Thing>
    <!-- RFC3229 headers end -->

    <!-- RFC3230 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#sigest">
      <rdfs:label xml:lang="en">Digest</rdfs:label>
      <rdfs:comment xml:lang="en">The Digest header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#want-digest">
      <rdfs:label xml:lang="en">Want-Digest</rdfs:label>
      <rdfs:comment xml:lang="en">The Want-Digest header</rdfs:comment>
    </owl:Thing>
    <!-- RFC3230 headers end -->

    <!-- RFC3253 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#label">
      <rdfs:label xml:lang="en">Label</rdfs:label>
      <rdfs:comment xml:lang="en">The Label header</rdfs:comment>
    </owl:Thing>
    <!-- RFC3253 headers end -->

    <!-- RFC3648 headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#ordering-type">
      <rdfs:label xml:lang="en">Ordering-Type</rdfs:label>
      <rdfs:comment xml:lang="en">The Ordering-Type header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#position">
      <rdfs:label xml:lang="en">Position</rdfs:label>
      <rdfs:comment xml:lang="en">The Position header</rdfs:comment>
    </owl:Thing>
    <!-- RFC3648 headers end -->

    <!-- DRP headers start -->
    <!-- http://www.w3.org/TR/NOTE-drp-19970825 -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#content-id">
      <rdfs:label xml:lang="en">Content-ID</rdfs:label>
      <rdfs:comment xml:lang="en">The Content-ID header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#differential-id">
      <rdfs:label xml:lang="en">Differential-ID</rdfs:label>
      <rdfs:comment xml:lang="en">The Differential-ID header</rdfs:comment>
    </owl:Thing>
    <!-- DRP headers end -->

    <!-- Duplicate Suppression headers start -->
    <!--
      http://www.ietf.org/proceedings/98dec/I-D/draft-mogul-http-dupsup-00.txt
    -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#subok">
      <rdfs:label xml:lang="en">SubOK</rdfs:label>
      <rdfs:comment xml:lang="en">The SubOK header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#subst">
      <rdfs:label xml:lang="en">Subst</rdfs:label>
      <rdfs:comment xml:lang="en">The Subst header</rdfs:comment>
    </owl:Thing>
    <!-- Duplicate Suppression headers end -->

    <!-- Exploration of dynamic documents headers start -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#refresh">
      <rdfs:label xml:lang="en">Refresh</rdfs:label>
      <rdfs:comment xml:lang="en">The Refresh header</rdfs:comment>
    </owl:Thing>
    <!-- Exploration of dynamic documents headers end -->

    <!-- edge-arch headers start -->
    <!-- http://www.w3.org/TR/2001/NOTE-edge-arch-20010804 -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#surrogate-capability">
      <rdfs:label xml:lang="en">Surrogate-Capability</rdfs:label>
      <rdfs:comment xml:lang="en">The Surrogate-Capability header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#surrogate-control">
      <rdfs:label xml:lang="en">Surrogate-Control</rdfs:label>
      <rdfs:comment xml:lang="en">The Surrogate-Control header</rdfs:comment>
    </owl:Thing>
    <!-- edge-arch headers end -->

    <!-- HTML 4 headers start -->
    <!-- http://www.w3.org/TR/1999/REC-html401-19991224/ -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#content-script-type">
      <rdfs:label xml:lang="en">Content-Script-Type</rdfs:label>
      <rdfs:comment xml:lang="en">The Content-Script-Type header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#content-style-type">
      <rdfs:label xml:lang="en">Content-Style-Type</rdfs:label>
      <rdfs:comment xml:lang="en">The Content-Style-Type header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#default-style">
      <rdfs:label xml:lang="en">Default-Style</rdfs:label>
      <rdfs:comment xml:lang="en">The Default-Style header</rdfs:comment>
    </owl:Thing>
    <!-- HTML 4 headers end -->

    <!-- Object Headers headers start -->
    <!-- http://www.w3.org/Protocols/HTTP/Object_Headers.html -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#content-transfer-encoding">
      <rdfs:label xml:lang="en">Content-Transfer-Encoding</rdfs:label>
      <rdfs:comment xml:lang="en">The Content-Transfer-Encoding header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#cost">
      <rdfs:label xml:lang="en">Cost</rdfs:label>
      <rdfs:comment xml:lang="en">The Cost header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#message-id">
      <rdfs:label xml:lang="en">Message-ID</rdfs:label>
      <rdfs:comment xml:lang="en">The Message-ID header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#title">
      <rdfs:label xml:lang="en">Title</rdfs:label>
      <rdfs:comment xml:lang="en">The Title header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#version">
      <rdfs:label xml:lang="en">Version</rdfs:label>
      <rdfs:comment xml:lang="en">The Version header</rdfs:comment>
    </owl:Thing>
    <!-- Object Headers headers end -->

    <!-- OPS over HTTP headers start -->
    <!-- http://www.w3.org/TR/NOTE-OPS-OverHTTP -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#getprofile">
      <rdfs:label xml:lang="en">GetProfile</rdfs:label>
      <rdfs:comment xml:lang="en">The GetProfile header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#profileobject">
      <rdfs:label xml:lang="en">ProfileObject</rdfs:label>
      <rdfs:comment xml:lang="en">The ProfileObject header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#setprofile">
      <rdfs:label xml:lang="en">SetProfile</rdfs:label>
      <rdfs:comment xml:lang="en">The SetProfile header</rdfs:comment>
    </owl:Thing>
    <!-- OPS over HTTP headers end -->

    <!-- OPTIONS messages headers start -->
    <!--
      http://www.watersprings.org/pub/id/draft-ietf-http-options-02.txt
    -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#compliance">
      <rdfs:label xml:lang="en">Compliance</rdfs:label>
      <rdfs:comment xml:lang="en">The Compliance header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#non-compliance">
      <rdfs:label xml:lang="en">Non-Compliance</rdfs:label>
      <rdfs:comment xml:lang="en">The Non-Compliance header</rdfs:comment>
    </owl:Thing>
    <!-- OPTIONS messages headers end -->

    <!-- P3P headers start -->
    <!-- http://www.w3.org/TR/2002/REC-P3P-20020416/ -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#p3p">
      <rdfs:label xml:lang="en">P3P</rdfs:label>
      <rdfs:comment xml:lang="en">The P3P header</rdfs:comment>
    </owl:Thing>
    <!-- P3P headers end -->

    <!-- PEP headers start -->
    <!-- http://www.w3.org/TR/WD-http-pep-960820 -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#c-pep">
      <rdfs:label xml:lang="en">C-PEP</rdfs:label>
      <rdfs:comment xml:lang="en">The C-PEP header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#c-pep-info">
      <rdfs:label xml:lang="en">C-PEP-Info</rdfs:label>
      <rdfs:comment xml:lang="en">The C-PEP-Info header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#pep">
      <rdfs:label xml:lang="en">PEP</rdfs:label>
      <rdfs:comment xml:lang="en">The PEP header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#pep-info">
      <rdfs:label xml:lang="en">Pep-Info</rdfs:label>
      <rdfs:comment xml:lang="en">The Pep-Info header</rdfs:comment>
    </owl:Thing>
    <!-- PEP headers end -->

    <!-- PICSLabels headers start -->
    <!-- http://www.w3.org/TR/REC-PICS-labels-961031 -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#pics-label">
      <rdfs:label xml:lang="en">PICS-Label</rdfs:label>
      <rdfs:comment xml:lang="en">The PICS-Label header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#protocol">
      <rdfs:label xml:lang="en">Protocol</rdfs:label>
      <rdfs:comment xml:lang="en">The Protocol header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#protocol-request">
      <rdfs:label xml:lang="en">Protocol-Request</rdfs:label>
      <rdfs:comment xml:lang="en">The Protocol-Request header</rdfs:comment>
    </owl:Thing>
    <!-- PICSLabels headers end -->

    <!-- Proxy Notification headers start -->
    <!-- http://www.w3.org/TR/WD-proxy-960221 -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#proxy-features">
      <rdfs:label xml:lang="en">Proxy-Features</rdfs:label>
      <rdfs:comment xml:lang="en">The Proxy-Features header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#proxy-instruction">
      <rdfs:label xml:lang="en">Proxy-Instruction</rdfs:label>
      <rdfs:comment xml:lang="en">The Proxy-Instruction header</rdfs:comment>
    </owl:Thing>
    <!-- Proxy Notification headers end -->

    <!-- Selecting Payment Mechanisms headers start -->
    <!-- http://www.w3.org/TR/NOTE-jepi-970519 -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#protocol-info">
      <rdfs:label xml:lang="en">Protocol-Info</rdfs:label>
      <rdfs:comment xml:lang="en">The Protocol-Info header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#protocol-query">
      <rdfs:label xml:lang="en">Protocol-Query</rdfs:label>
      <rdfs:comment xml:lang="en">The Protocol-Query header</rdfs:comment>
    </owl:Thing>
    <!-- Selecting Payment Mechanisms headers end -->

    <!-- SOAP headers start -->
    <!-- http://www.w3.org/TR/2000/NOTE-SOAP-20000508 -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#soapaction">
      <rdfs:label xml:lang="en">SoapAction</rdfs:label>
      <rdfs:comment xml:lang="en">The SoapAction header</rdfs:comment>
    </owl:Thing>
    <!-- SOAP headers end -->

    <!-- UA Attributes headers start -->
    <!--
      http://www.watersprings.org/pub/id/draft-mutz-http-attributes-00.txt
    -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#ua-color">
      <rdfs:label xml:lang="en">UA-Color</rdfs:label>
      <rdfs:comment xml:lang="en">The UA-Color header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#ua-media">
      <rdfs:label xml:lang="en">UA-Media</rdfs:label>
      <rdfs:comment xml:lang="en">The UA-Media header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#ua-pixels">
      <rdfs:label xml:lang="en">UA-Pixels</rdfs:label>
      <rdfs:comment xml:lang="en">The UA-Pixels header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#ua-resolution">
      <rdfs:label xml:lang="en">UA-Resolution</rdfs:label>
      <rdfs:comment xml:lang="en">The UA-Resolution header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#ua-windowpixels">
      <rdfs:label xml:lang="en">UA-Windowpixels</rdfs:label>
      <rdfs:comment xml:lang="en">The UA-Windowpixels header</rdfs:comment>
    </owl:Thing>
    <!-- UA Attributes headers end -->

    <!-- WIRE headers start -->
    <!--
      http://www.ietf.org/proceedings/98dec/I-D/draft-girod-w3-id-res-ext-00.txt
    -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#optional">
      <rdfs:label xml:lang="en">Optional</rdfs:label>
      <rdfs:comment xml:lang="en">The Optional header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#resolution-hint">
      <rdfs:label xml:lang="en">Resolution-Hint</rdfs:label>
      <rdfs:comment xml:lang="en">The Resolution-Hint header</rdfs:comment>
    </owl:Thing>
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#resolver-location">
      <rdfs:label xml:lang="en">Resolver-Location</rdfs:label>
      <rdfs:comment xml:lang="en">The Resolver-Location header</rdfs:comment>
    </owl:Thing>
    <!-- WIRE headers end -->

    <!-- new header name, stub for subclassing -->
    <owl:Thing rdf:about="http://www.w3.org/2006/http-header#NewHeaderName"/>
  </owl:oneOf>
</rdfs:Class>

<rdfs:Class rdf:about="http://www.w3.org/2006/http-header#NewHeaderName">
  <rdfs:label xml:lang="en">New header name</rdfs:label>
  <rdfs:comment xml:lang="en">New HTTP header name. If you want to define new header names, subclass this stub.</rdfs:comment>
</rdfs:Class>

</rdf:RDF>

Appendix B: Security and Privacy

There are also noteable 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.

Appendix C: Vocabulary Terms

The following terms are defined by this specification:

Classes

Properties

Values

Appendix D: Practical Example

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

Scenario Description

A client requests a resource in the document root (/foo/bar) at www.example.org port 80 via HTTP 1.1. With the request, it sends request headers. The server uses content negotiation. Some of the request headers (accept and accept-language) are relevant for the creation or choice of the result as indicated by the vary reponse header. Thus, at least these request headers are recorded in the representation of the request. In addition to the content-type and vary headers, the server sends an unknown header (x-foo) which appears as a Message Header. The body property contains the result as an XML literal.

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#">
  <http:Connection rdf:ID="conn">
    <http:connectionAuthority>www.example.org:80</http:connectionAuthority>
    <http:request rdf:parseType="Collection">
      <http:Request rdf:about="#req0"/>
      <http:Request rdf:about="#req1"/>
    </http:request>
  </http:Connection>
  <http:GetRequest rdf:ID="req0">
    <http:abs_path>/foo/bar</http:abs_path>
    <http:version>1.1</http:version>
    <http:header rdf:parseType="Collection">
      <http:MessageHeader>
        <http:fieldName rdf:resource="http://www.w3.org/2006/http-header#accept"/>
        <http:fieldValue rdf:parseType="Collection">
          <http:HeaderElement>
            <http:elementName>text/html</http:elementName>
            <http:param>
              <http:Param>
                <http:paramName>q</http:paramName>
                <http:paramValue>1.0</http:paramValue>
              </http:Param>
            </http:param>
          </http:HeaderElement>
          <http:HeaderElement>
            <http:elementName>application/xml</http:elementName>
            <http:param>
              <http:Param>
                <http:paramName>q</http:paramName>
                <http:paramValue>0.9</http:paramValue>
              </http:Param>
            </http:param>
          </http:HeaderElement>
          <http:HeaderElement>
            <http:elementName>*/*</http:elementName>
            <http:param>
              <http:Param>
                <http:paramName>q</http:paramName>
                <http:paramValue>0.01</http:paramValue>
              </http:Param>
            </http:param>
          </http:HeaderElement>
        </http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName rdf:resource="http://www.w3.org/2006/http-header#accept-language"/>
        <http:fieldValue rdf:parseType="Collection">
          <http:HeaderElement>
            <http:elementName>de-DE</http:elementName>
            <http:param>
              <http:Param>
                <http:paramName>q</http:paramName>
                <http:paramValue>1.0</http:paramValue>
              </http:Param>
            </http:param>
          </http:HeaderElement>
          <http:HeaderElement>
            <http:elementName>de</http:elementName>
            <http:param>
              <http:Param>
                <http:paramName>q</http:paramName>
                <http:paramValue>0.75</http:paramValue>
              </http:Param>
            </http:param>
          </http:HeaderElement>
          <http:HeaderElement>
            <http:elementName>en-GB</http:elementName>
            <http:param>
              <http:Param>
                <http:paramName>q</http:paramName>
                <http:paramValue>0.5</http:paramValue>
              </http:Param>
            </http:param>
          </http:HeaderElement>
          <http:HeaderElement>
            <http:elementName>en</http:elementName>
            <http:param>
              <http:Param>
                <http:paramName>q</http:paramName>
                <http:paramValue>0.25</http:paramValue>
              </http:Param>
            </http:param>
          </http:HeaderElement>
          <http:HeaderElement>
            <http:elementName>*</http:elementName>
            <http:param>
              <http:Param>
                <http:paramName>q</http:paramName>
                <http:paramValue>0.01</http:paramValue>
              </http:Param>
            </http:param>
          </http:HeaderElement>
        </http:fieldValue>
      </http:MessageHeader>
    </http:header>
    <http:response rdf:resource="#resp0"/>
  </http:GetRequest>
  <http:GetRequest rdf:ID="req1">
    <http:abs_path>/images/foo.png</http:abs_path>
    <http:version>1.1</http:version>
    <http:header>
      <http:MessageHeader>
        <http:fieldName rdf:resource="http://www.w3.org/2006/http-header#accept"/>
        <http:fieldValue rdf:parseType="Collection">
          <http:HeaderElement>
            <http:elementName>image/png</http:elementName>
            <http:param>
              <http:Param>
                <http:paramName>q</http:paramName>
                <http:paramValue>1.0</http:paramValue>
              </http:Param>
            </http:param>
          </http:HeaderElement>
          <http:HeaderElement>
            <http:elementName>image/jpeg</http:elementName>
            <http:param>
              <http:Param>
                <http:paramName>q</http:paramName>
                <http:paramValue>0.9</http:paramValue>
              </http:Param>
            </http:param>
          </http:HeaderElement>
          <http:HeaderElement>
            <http:elementName>*/*</http:elementName>
            <http:param>
              <http:Param>
                <http:paramName>q</http:paramName>
                <http:paramValue>0.01</http:paramValue>
              </http:Param>
            </http:param>
          </http:HeaderElement>
        </http:fieldValue>
      </http:MessageHeader>
    </http:header>
    <http:response rdf:resource="#resp1"/>
  </http:GetRequest>
  <http:Response rdf:ID="resp0">
    <http:responseCode rdf:resource="http://www.w3.org/2006/http#200"/>
    <http:version>1.1</http:version>
    <http:header rdf:parseType="Collection">
      <http:MessageHeader>
        <http:fieldName rdf:resource="http://www.w3.org/2006/http-header#content-type"/>
        <http:fieldValue>
          <http:HeaderElement>
            <http:elementName>application/xhtml+xml</http:elementName>
            <http:param>
              <http:Param>
                <http:paramName>charset</http:paramName>
                <http:paramValue>utf-8</http:paramValue>
              </http:Param>
            </http:param>
          </http:HeaderElement>
        </http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName rdf:resource="http://www.w3.org/2006/http-header#vary"/>
        <http:fieldValue rdf:parseType="Collection">
          <http:HeaderElement>
            <http:elementName>accept</http:elementName>
          </http:HeaderElement>
          <http:HeaderElement>
            <http:elementName>accept-language</http:elementName>
          </http:HeaderElement>
        </http:fieldValue>
      </http:MessageHeader>
      <http:MessageHeader>
        <http:fieldName>x-foo</http:fieldName>
        <http:fieldValue>bar</http:fieldValue>
      </http:MessageHeader>
    </http:header>
    <http:body rdf:parseType="Literal">
      <html xmlns="http://www.w3.org/1999/xhtml">
        <head>
          <title>Hello World!</title>
        </head>
        <body>
          <p>Hello World!
            <img src="/images/foo.png" alt="foo" width="5" height="7" /></p>
        </body>
      </html>
    </http:body>
  </http:Response>
  <http:Response rdf:ID="resp1">
    <http:responseCode rdf:resource="http://www.w3.org/2006/http#200"/>
    <http:version>1.1</http:version>
    <http:header>
      <http:MessageHeader>
        <http:fieldName rdf:resource="http://www.w3.org/2006/http-header#content-type"/>
        <http:fieldValue>image/png</http:fieldValue>
      </http:MessageHeader>
    </http:header>
    <http:body rdf:resource="data:base64,vjbo38g53oguo3w82ghin24oz284hhghlw"/>
  </http:Response>
</rdf:RDF>

Appendix E: Document Changes

The following is a list of changes since the 20 December, 2006 Working Draft:

• added a wrapper http:Connection class to describe the actual TCP connection
• added http:response property to the request class to relate responses
• dropped URI property (and namespace) in favor of a requestURI property
• dropped references to RFC 822 (not needed for the scope of this work)
• added pre-defined constant values for the http:responseCode property
• added list of terms that describe the classes, properties, and values in the schema
• changed the usage of the body property to allow any type of data (using an algorithm)

Appendix F: References

[DRP]

"The HTTP Distribution and Replication Protocol" - Arthur van Hoff, John Giannandrea, Mark Hapner, Steve Carter, Milo Medin, W3C Member Submission, 25 August 1997.

[DupSup]

"Duplicate Suppression in HTTP" - Jeffrey Mogul, Arthur van Hoff, IETF Internet-Draft, 15 April 1998.

[EARL Schema]

"Evaluation and Report Language (EARL) 1.0 Schema" - Charles McCathieNevile, Shadi Abou-Zahra, W3C Editors' Working Draft 01 January 2006.

[EDD]

"An exploration of dynamic documents" - Netscape, 1999.

[EdgeArch]

"Edge Architecture Specification" - Mark Nottingham, Xiang Liu, W3C Note, 04 August 2001.

[HttpClient]

Jakarta Commons HttpClient

[HTML4]

"HTML 4.01 Specification" - Dave Raggett, Arnaud Le Hors, Ian Jacobs, W3C Recommendation, 24 December 1999.

[JEPI]

"White Paper: Joint Electronic Payment Initiative" - Eui-Suk Chung, Daniel Dardailler, W3C NOTE, 19 May 1997.

[ObjectHeaders]

"Object Header lines in HTTP" - T. Berners-Lee, May 1994.

[OPS-OverHTTP]

"Implementation of OPS Over HTTP" - Pat Hensley, Max Metral, Upendra Shardanand, Donna Converse, Mike Myers, W3C Member Submission, 02 June 1997.

[OPTIONS messages]

"Specification of HTTP/1.1 OPTIONS messages" - J. Mogul, J. Cohen, S. Lawrence, IETF Internet-Draft, 26 August 1997.

[P3P]

"The Platform for Privacy Preferences 1.0 (P3P1.0) Specification" - Lorrie Cranor, Marc Langheinrich, Massimo Marchiori, Martin Presler-Marshall, Joseph Reagle, W3C Recommendation, 16 April 2002.

[PEP]

"PEP - an Extension Mechanism for HTTP" - Henrik Frystyk Nielsen, Dan Connolly, Rohit Khare, Eric Prud'hommeaux, W3C Working Draft, 21 November 1997.

[PICSLabels]

"PICS Label Distribution Label Syntax and Communication Protocols, Version 1.1" - Tim Krauskopf, Jim Miller, Paul Resnick, Win Treese, W3C Recommendation, 31 October 1996.

[Proxy Notification]

"Notification for Proxy Caches" - Phillip M. Hallam-Baker, W3C Working Draft, 21 February 1996.

[RDF]

"Resource Description Framework (RDF): Concepts and Abstract Syntax" - Graham Klyne, Jeremy J. Carroll, W3C Recommendation, 10 February 2004.

[RDF-PRIMER]

RDF Primer - Frank Manola, Eric Miller (eds.). W3C Recommendation, 10 February 2004.

[RFC2068]

"Hypertext Transfer Protocol -- HTTP/1.1" - R. Fielding, J. Gettys, J. Mogul, H. Frystyk, T. Berners-Lee, January 1997.

[RFC2109]

"HTTP State Management Mechanism" - D. Kristol, L. Montulli, February 1997.

[RFC2183]

"Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field" - R. Troost, S. Dorner, K. Moore, August 1997.

[RFC2227]

"Simple Hit-Metering and Usage-Limiting for HTTP" - J. Mogul, P. Leach, October 1997.

[RFC2295]

"Transparent Content Negotiation in HTTP" - K. Holtman, A. Mutz, March 1998.

[RFC2310]

"The Safe Response Header Field" - K. Holtman, April 1998.

[RFC2324]

"Hyper Text Coffee Pot Control Protocol (HTCPCP/1.0)" - L. Masinter, 1 April 1998.

[RFC2397]

"The 'data' URL scheme" - L. Masinter, August 1998.

[RFC2518]

"HTTP Extensions for Distributed Authoring -- WEBDAV" - Y. Goland, E. Whitehead, A. Faizi, S. Carter, D. Jensen, February 1999.

[RFC2616]

"Hypertext Transfer Protocol -- HTTP/1.1" - R. Fielding, J. Gettys, J. Mogul, H. Frystyk Nielsen, L. Masinter, P. Leach and T. Berners-Lee, June 1999.

[RFC2617]

"HTTP Authentication: Basic and Digest Access Authentication" - J. Franks, P. Hallam-Baker, J. Hostetler, S. Lawrence, P. Leach, A. Luotonen, L. Stewart, June 1999.

[RFC2660]

"The Secure HyperText Transfer Protocol" - E. Rescorla, A. Schiffman, August 1999.

[RFC2774]

"An HTTP Extension Framework" - H. Nielsen, P. Leach, S. Lawrence, February 2000.

[RFC2965]

"HTTP State Management Mechanism" - D. Kristol, L. Montulli, October 2000.

[RFC3229]

"Delta encoding in HTTP" – J. Mogul, B. Krishnamurthy, F. Douglis, A. Feldmann, Y. Goland, A. van Hoff, D. Hellerstein, January 2002.

[RFC3230]

"Instance Digests in HTTP" – J. Mogul, A. van Hoff, January 2002.

[RFC3253]

"Versioning Extensions to WebDAV (Web Distributed Authoring and Versioning)" - G. Clemm, J. Amsden, T. Ellison, C. Kaler, J. Whitehead, March 2002.

[RFC3648]

"Web Distributed Authoring and Versioning (WebDAV) Ordered Collections Protocol" - J. Whitehead, J. Reschke, Ed., December 2003.

[RFC3986]

"Uniform Resource Identifier (URI): Generic Syntax" - T. Berners-Lee, R. Fielding, L. Masinter, January 2005.

[RFC4229]

"HTTP Header Field Registrations" - M. Nottingham, J. Mogul. December 2005.

[SOAP1.1]

"Simple Object Access Protocol (SOAP) 1.1" - Don Box, David Ehnebuske, Gopal Kakivaya, Andrew Layman, Noah Mendelsohn, Henrik Frystyk Nielsen, Satish Thatte, Dave Winer, W3C Note, 08 May 2000.

[UA Attributes]

"User-Agent Display Attributes Headers" - A. Mutz, L. Montulli, L. Masinter, IETF Internet-Draft, 12 June 1996.

[WCAG]

@@@TBD@@@

[WIRE]

"WIRE - W3 Identifier Resolution Extensions" - Lewis Girod, Benjie Chen, Henrik Frystyk, John Mallery, IETF Internet-Draft, 13 March 1998.