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| − | == Introduction == | + | [[Image:Higgins_logo_76Wx100H.jpg|right]] |
| − | This page describes and defines a Higgins [[ContextId]]. | + | == Version == |
| | + | This page describes the concept of a [[ContextId]] as used in [[Context Data Model 2.0]]. |
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| | == Definition == | | == Definition == |
| − | * A [[ContextId]] is a kind of [[Context Correlation]] | + | * An identifier of a [[Context]] |
| − | * A [[ContextId]] identifies a instance of a [[Context]]
| + | * A ''Context UDI'' as defined in [http://www.azigo.com/udi/udi-syntax.html UDI Syntax] |
| − | * A [[ContextId]] MUST have a single value of type [[ContextIdDatatype]] | + | |
| − | * If a [[Context]] has a [[ContextId]] [[Attribute]] its value identifies the [[Context]] itself.
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| − | == Details ==
| + | [[Category:Context Data Model 2.0]] |
| − | * The value of a [[ContextId]] must directly or indirectly (e.g. by resolution) provide sufficient information to identify a [[Context]]. See the ''Context Discovery with a ContextId'' heading below.
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| − | * Two different [[ContextId]]s may refer to the same [[Context]].
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| − | == ContextId and IdAS ==
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| − | * 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 [[Digital Identity|Digital Identities]] may see different subsets of the [[Context]] based on the authorization passed in during authentication.
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| − | * A given [[ContextId]] may be used against multiple [[Context Provider]]s to produce the same [[Context]] (although, as mentioned, different [[Context]] instances).
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| − | == Details ==
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| − | * The [[Identity Attribute Service (IdAS)]] can be used as a service to access a [[Context]] given a [[ContextId]]
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| − | Some [[ContextId]]s are not resolvable to a [[Context]] instance. Most [[Context]]s are not abstract. Using a network (or local) data access service their [[ContextId]]s are resolvable to data objects that are instantiated and managed by [[Context Provider]] plug-ins.
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| − | == Relationship to OpenID ==
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| − | Any OpenID 2.0 identifier as defined by [http://openid.net/specs/openid-authentication-2_0.html OpenID Authentication 2.0] may function as a Higgins [[ContextId]]. OpenID 2.0 supports both URLs and XRIs. All of the examples of contexthttpURI and contextXRI above are valid OpenID 2.0 identifiers.
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| − | The only caveat to keep in mind is that if an OpenID 2.0 URL is used as a Higgins [[ContextId]], the XRDS or XDI document to which it resolves must EITHER contain:
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| − | * Only one XRDS service endpoint or XDI context reference describing the target [[Context]], OR
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| − | * The consuming application must know how to select the XRDS service endpoint or XDI context reference it requires (i.e., it must know which Higgins [[Context Type]] it is seeking).
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| − | == Open Issues ==
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| − | # Should the contextId ABNF support IRI (Internationalized Resource Identifiers) and not just URIs? Note that the ABNF above uses IRI rules; this needs to be changed if only URIs will be supported.
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| − | == See Also ==
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| − | * [[EntityId]]
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| − | * [[LocalId]]
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| − | * [[Context Discovery]]
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| − | * [[Context Discovery Components]]
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| − | * [[Higgins XRDS Service Endpoint]]
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| − | * [[Higgins XDI Context Reference]]
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| − | * [[Concepts]]
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| − | == Links ==
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| − | * [http://eclipse.org/higgins Higgins Home]
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