Difference between revisions of "IdAS XDI Mapping"

Revision as of 18:40, 9 March 2008

This page explains the relation between the Higgins Data Model (which is implemented by IdAS) and XDI. XDI ("XRI Data Interchange") is a data model and protocol for sharing, linking, and synchronizing data over the Internet ("structured web") and other networks using Extensible Resource Identifiers (XRIs). It is being developed by the OASIS XDI Technical Committee.

This page consists of two parts: A list of theoretical mappings between Higgins Data Model concepts and XDI concepts, and a list of mappings between concrete IdAS operations and concrete XDI operations.

The IdAS XDI Engine maps the Higgins Data Model to XDI and maps XDI operations to IdAS operations. In other words, it produces the XDI examples on this page.

The XDI Context Provider maps XDI to the Higgins Data Model and maps IdAS operations to XDI operations. In other words, it consumes the XDI examples on this page.

Mapping the Higgins Data Model to XDI

Since the Higgins Data Model is based on RDF/OWL, and since XDI is also (conceptually) based on RDF, the basic mapping is straight-forward. However, some attention has to be paid to details.

Roughly speaking, a Higgins context can be mapped to an XDI graph using the following rules:

• A Higgins Node maps to an XDI subject
• A Higgins Attribute maps to an XDI predicate
• Values of Higgins Attributes map to XDI literals
• A Higgins Relation maps to an XDI predicate
• A Higgins Correlation maps to the special $is XDI predicate
• A Higgins NodeId maps to an XRI

Mapping Higgins IdAS operation to XDI operations

Using IdAS, a Higgins context can be opened, and operations can be performed on it. The equivalent in XDI is XDI messages (which contain XDI operations).

The following sub-sections each list the following:

• A typical IdAS operation (the sub-section header).
• The IdAS calls that perform the operation.
• An XDI message produced by the XDI Context Provider (the first XDI example in the sub-section).
• An XDI result document produced by the XDI Engine (the second XDI example in the sub-section).

All XDI examples are in the X3 Simple serialization format. See X3Format for more information about X3 serialization formats.

List all Nodes in the Context

IdAS calls:

Iterator<Node> nodes = IContext.getNodes(null);

Message sent by the XDI Context Provider:

=sender
	$get

Reply from the XDI Engine:

=markus
	+(http://www.example.com/name)
		/
			$
				$1
					"Markus Sabadello"
	+(http://www.example.com/location)
		/
			$
				$1
					"Vienna"
=drummond
	+(http://www.example.com/name)
		/
			$
				$1
					"Drummond Reed"

Gets one Node from the Context

IdAS calls:

Node node = IContext.getNode("=markus");

Message sent by the XDI Context Provider:

=sender
	$get
		/
			=markus

Reply from the XDI Engine:

=markus
	+(http://www.example.com/name)
		/
			$
				$1
					"Markus Sabadello"
	+(http://www.example.com/location)
		/
			$
				$1
					"Vienna"

Get one Attribute from a Node

IdAS calls:

IAttribute attribute = IContext.getNode("=markus").getAttribute("http://www.example.com/someAttributeId");

Message sent by the XDI Context Provider:

=sender
	$get
		/
			=markus
				+(http://www.example.com/name)

Reply from the XDI Engine:

=markus
	+(http://www.example.com/name)
		/
			$
				$1
					"Markus Sabadello"

Remove a Node from the Context

IdAS calls:

IContext.getNode("=markus").remove();

Message sent by the XDI Context Provider:

=sender
	$del
		/
			=markus

Reply from the XDI Engine: (none)

Change a Value of an Attribute

IdAS calls:

INode node = context.getNode("=markus");
IAttribute attribute = node.getAttribute(new URI("http://www.example.com/name"));
Iterator<IAttributeValue> values = (Iterator<IAttributeValue>) attribute.getValues();
IAttributeValue value = values.next();
((ITypedValue) value).setData("M.S.");

Message sent by the XDI Context Provider:

=sender
	$mod
		/
			=markus
				+(http://www.example.com/name)
					/
						$
							$1
								"M.S."

Reply from the XDI Engine: (none)

IContext.getSchema()

Gets the schema of the Context.

TODO

IContext.getRelationships()

Gets all Context Relations and Context Correlations.

TODO

Authorization

Authorization support in IdAS maps to XDI link contracts.

TODO

Notifications

Notification support in IdAS maps to XDI links contracts.

TODO

Links

• Higgins Home
• The XDI RDF Model is the current OASIS TC proposal for an RDF-based data model and addressing format for XDI. This document includes the proposed XDI RDF schema and a number of examples of XDI documents. (Note that it does not yet include the proposed XDI messaging format, which uses XDI documents as message envelopes for other XDI documents.)
• OASIS XDI TC Wiki
• Wikipedia page on XDI