Difference between revisions of "ContextId"

Revision as of 14:25, 18 March 2008

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Introduction

This page describes and defines a Higgins ContextId.

Definition

• A ContextId is a kind of Attribute that uniquely identifies a Context.
• The value of a ContextId MUST be a single instance of a ContextId Data Range.
• Two different ContextIds may refer to the same Context.
• If the value of a ContextId is resolvable, its value should dereference the information necessary to discover how to access a Context. See Context Discovery.

Details

• It is not required for a ContextIds to resolve to a Context instance in which case this is referred to as an abstract ContextId. However, most Contexts are not abstract, and can be resolved a network (or local) data access service to discover the information necessary to access the Context.

ContextIds and IdAS

• The Identity Attribute Service (IdAS) can be used as a service to access a Context given a ContextId.
• If two ContextId's values are equal, they refer to the same underlying Context, although not necessarily the same Context "container" instance returned by IdAS. This means that, as a requester of information, different clients of IdAS may see different subsets of the Context based on the authorization passed in during authentication.
• A given ContextId may be used against multiple Context Providers to produce the same Context (although, as mentioned, different Context instances).

See Also

• NodeId
• Context Discovery
• Context Discovery Components
• Higgins XRDS Service Endpoint
• Higgins XDI Context Descriptor
• Concepts