One document matched: draft-snell-additional-link-relations-06.xml


<?xml version="1.0"?> 
<!DOCTYPE rfc SYSTEM "rfc2629.dtd" [
  <!ENTITY rfc5988 PUBLIC '' 'http://xml.resource.org/public/rfc/bibxml/reference.RFC.5988.xml'>
]>
<?rfc toc="yes"?> 
<?rfc strict="yes"?> 
<?rfc symrefs="yes" ?> 
<?rfc sortrefs="yes"?> 
<?rfc compact="yes"?> 
<rfc category="info" ipr="trust200811" docName="draft-snell-additional-link-relations-06"> 
  <front> 
    <title abbrev="Additional Link Relations"> 
      Additional Link Relation Types
    </title> 
 
    <author initials="J.M." surname="Snell" fullname="James M Snell"> 
      <address> 
        <email>jasnell@gmail.com</email> 
      </address> 
    </author> 
    
    <date month="October" year="2012" /> 
 
    <area>Applications</area> 
    <keyword>I-D</keyword> 
    <keyword>http</keyword> 
    <keyword>link</keyword> 
    <keyword>rel</keyword>
 
    <abstract> 
      <t>This specification defines a number of additional Link Relation Types
      that can used for a variety of purposes..</t> 
    </abstract> 
 
  </front> 
  
  <middle> 
    <section anchor="intro" title="Introduction"> 
 
      <t>The fundamental model for Web Links and the Registry of Link
      Relations are established by <xref target="RFC5988"/>. This specification 
      defines and adds the following additional types of link relations to 
      the registry: about, preview, privacy-policy, terms-of-service, and type.</t>
      
    </section> 
        
    <section anchor="about" title=""about"">
    
      <t>The "about" Link relation can be used to refer to a resource
      that is the subject or topic of the link's context. Multiple 
      subjects can be indicated through the use of multiple "about" link 
      relations.</t>
      
      <t>For example, if the context resource is a review about a particular
      product, the "about" link can be used to reference the URL of the 
      product:</t>
      
      <figure><artwork><![CDATA[
  HTTP/1.1 200 OK
  Content-Type: application/json
  Link: <http://store.example.org/product/abc>; rel="about"
  
  {...}
      ]]></artwork></figure>
      
    </section>
        
    <section anchor="preview" title=""preview"">
    
      <t>The "preview" Link relation can be used to refer to a resource
      that serves as a preview of the link's context, likely with reduced
      quality or limited content. For instance, the preview link might reference
      a screen capture of a video, a brief snippet of audio from a 
      song or a thumbnail representation of an image.</t>
      
      <t>For example, issuing a HTTP HEAD request to a URI representing a 
      large video or image file might return a link to a short or lower
      quality preview of the original:</t>
      
      <figure><artwork><![CDATA[
  HTTP/1.1 200 OK
  Content-Text: video/mpeg
  Link: <http://example.org/preview/10-second-preview.mpg>; 
    rel="preview"; type="video/mpeg"
        ]]></artwork></figure> 
        
    </section>
        
    <section anchor="privacy-policy" title=""privacy-policy"">

      <t>The "privacy-policy" Link relation can be used to refer to a 
      resource describing the privacy policy associated with the link's
      context. The privacy policy can be any resource that discloses what
      personal information about the user is collected, and how that 
      personal information is stored, used, managed and disclosed to other
      parties.</t>
      
      <t>For example, an HTTP server that collects personal information 
      about a user throughout the course of the user's interaction with 
      the service can include "privacy-policy" Links within all HTTP 
      Responses using any combination of Link headers or links embedded 
      in the response payload:</t>

      <figure><artwork><![CDATA[
  HTTP/1.1 200 OK
  Content-Type: text/html
  
  <html>
    <head>
      ...
      <link rel="privacy-policy" href="/privacy-policy.html" />
      ...
    </head>
    <body>
      ...
    </body>    
  </html>
      ]]></artwork></figure>
      
      <t>Note that in the absence of clear legal obligations placed on an 
      entity either through contract or law, the presence of a "privacy-policy" 
      Link does not constitute a legally binding obligation on the part of the 
      service. The linked resource can only be interpreted as a description of 
      the expected practice.</t>
      
      <t>It is recommended that publishers of privacy policy resources linked to 
      using the "privacy-policy" Link relation provide a clear and simple mechanism
      for signaling when changes to the Privacy Policy resource have been made, 
      such as generating a new Entity Tag for the resource or generating a hash
      over the Privacy Policy's content. How much mechanisms are utilized are out
      of the scope of this specification, however.</t>
      
    </section>
    
    <section anchor="terms-of-service" title=""terms-of-service"">
    
      <t>The "terms-of-service" Link relation can be used to refer to a 
      resource describing the Terms of Service associated with the link's
      context. The Terms of Service can be any resource that describes the 
      rules to which a consumer of the service must agree to follow when 
      using the service provided by the link's context.</t>
      
      <t>For example, an HTTP server can include "terms-of-service" Links
      within all HTTP Responses using any combination of Link headers or 
      links embedded in the response payload:</t>
      
      <figure><artwork><![CDATA[
  HTTP/1.1 200 OK
  Content-Type: text/html
  
  <html>
    <head>
      ...
      <link rel="terms-of-service" href="/tos.html">
      ...
    </head>
    <body>
      ...
    </body>    
  </html>
      ]]></artwork></figure>
      
      <t>It must be noted that the Terms of Service linked to using this
      link relation carries no legal weight and can be ignored with impunity
      in the absence of an explicit, legally enforceable contract. The 
      linked Terms of Service are simply a notice of the terms that may be 
      expected to apply once a contract is established.</t>
    
    </section>
    
    <section anchor="type" title=""type"">
    
      <t>The "type" Link relation can be used to indicate that the context
      resource is an instance of the resource identified by the target IRI.</t>
      
      <figure><artwork><![CDATA[
  HTTP/1.1 200 OK
  Content-Type: text/plain
  Link: <http://example.org/Person/givenName>; rel="type"
  
  Sally
      ]]></artwork></figure>
      
      <t>When used within the header of an HTTP message, the "type" specified 
      by the type link relation cannot be confused with the content type of 
      the payload as given by the Content-Type header. The "type" link relation 
      references the payload's abstract semantic type whereas the Content-Type 
      header identifies the specific serialization format of the payload.</t>
      
      <t>If the context can be considered to be an instance of multiple 
      semantic types, multiple "type" link relations can be used.</t>
      
    </section>
      
    <section title="IANA Considerations"> 
      
      <t>The Registry of Link Relations should be updated with the following
      entries:</t>
      
      <t><list style="symbols">
        <t>Relation Name: about</t>
        <t>Description: Refers to a resource that is the subject of the link's
        context.</t>
        <t>Reference: This specification, <xref target="about"/></t>
      </list></t>
      
      <t><list style="symbols">
        <t>Relation Name: preview</t>
        <t>Description: Refers to a resource that provides a preview of the 
        link's context.</t>
        <t>Reference: This specification, <xref target="preview"/></t>
      </list></t>
      
      <t><list style="symbols">
        <t>Relation Name: privacy-policy</t>
        <t>Description: Refers to a Privacy Policy associated with the link's
        context.</t>
        <t>Reference: This specification, <xref target="privacy-policy"/></t>
      </list></t>
      
      <t><list style="symbols">
        <t>Relation Name: terms-of-service</t>
        <t>Description: Refers to the Terms of Service associated with the 
        link's context.</t>
        <t>Reference: This specification, <xref target="terms-of-service"/></t>
      </list></t>
      
      <t><list style="symbols">
        <t>Relation Name: type</t>
        <t>Description: Refers to a resource identifying the abstract semantic
        type the link's context is considered to be an instance of.</t>
        <t>Reference: This specification, <xref target="type"/></t>
      </list></t>
      
    </section> 
 
    <section title="Security Considerations"> 
    
      <t>There are no additional security concerns introduced by this
      document.</t>
    
    </section> 
  </middle> 
 
  <back>
    <references title="Informative References">
      &rfc5988;
    </references>
  </back>
</rfc> 
 

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