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1 HTTP Rendering

1.1 Overview

TBD: Explain CRUD/REST here....

1.2 Versioning

1.3 Content-type and Accept headers

TBD: describe stuff here.... Impl should react on Accept and Content-type stuff...

1.4 Render OCCI model in the HTTP Header

Note: This is the default rendering mode for OCCI - It is the fallback. In some use cases (Collections, Query Interface) it needs to render stuff using specific Content-types like 'text/uri-list' or 'text/plain'

The HTTP header fields MUST follow the specification in RFC 2616. A header field consists of a name followed by a colon (":") and the field value. The format of the field value is specified separately for each of the three header fields, see below.

HTTP header fields MAY appear multiple times in a HTTP request or response. In order to be OCCI compliant the specification of multiple message-header fields according to RFC 2616 (section 4.2) MUST be fully supported. In essence there are two valid representation of multiple HTTP header field values. A header field might either appear several times or as a single header field with a comma-separated list of field values. Due to implementation issues in many web frameworks and client libraries it is RECOMMENDED to use the comma-separated list format for best interoperability.

HTTP header field values which contain separator characters MUST be properly quoted according to RFC 2616.

1.4.1 HTTP Header Fields

Three different HTTP header fields are used to render the OCCI model. Each header field value has a different format.

1.4.1.1 Category Header

The Category header is defined by the Web Categories specification, http://tools.ietf.org/html/draft-johnston-http-category-header-01. The semantics of the Category header in the OCCI context is described in the OCCI Core & Models document.

1.4.1.2 Link Header

The Link header is defined by the Web Linking specification, http://tools.ietf.org/html/draft-nottingham-http-link-header-10. The semantics of the Link header in the OCCI context is described in the OCCI Core & Models document.

1.4.1.3 Attribute Header

The Attribute header is used to render the attributes associated with a OCCI Resource. A simple key-value format is used. The field value consist of an attribute name followed by an equal sign ("=") and the attribute value. The attribute value must be quoted if it includes a separator character, see RFC 2616 (page 16).

Valid attribute names for OCCI Resources are specified in Extension documents.

The following handling MUST be implemented:

• Links also contain currently active Actions!

Note: to be HTTP compliant the body can contain an empty string

1.4.2 Examples

Note: there is no order for the optional parts.

Note: Whenevera request or response is generate there should be an Category rendering!

1.5 Render OCCI model in the HTTP Body

Note: In case that the Header Attributes become overfull, or collections are used the OCCI model MUST be rendered in the HTTP-Body. This MUST also be done when the Client requests 'text/plain'.

1.5.1 Examples

See above just that Category, Link and Attribute are now in the body... And ':' becomes '='

1.6 Render OCCI model via URL Listings

Note: This rendering cannot render Kinds of Categories directly but just Links to them. For concrete rendering of Kinds and Categories the Content-types '*/*', 'text/plain' must be used.

1.6.1 Examples

Contributors

• Editors: Andy Edmonds, Thijs Metsch
• Contributors: Ralf Nyrén, Sam Johnston