Difference between revisions of "Metadata Retriever Plugins"

First Phase

Operators may wish to include metadata about Resources from other sources, including web services (ie, Semantic Analysis), databases, or something else. This describes how to implement a plugin to import this information.

A plugin implements IMetadataImporter, which provides a single method, loadMetadata. loadMetadata takes a Resource, and is responsible for adding any fields to it. loadMetadata is not responsible for persisting the Resource.

The initial prototype will log URLs as it goes.

The first working plug-in could exercise the del.icio.us API to retrieve tags that delicious users have placed on a URI. Example: api.del.icio.us /v1/posts/suggest?url=http://ocw.nd.edu/computer-applications/applied-multimedia-technology

To accomplish this...

• enable resources to allow dynamic metadata to be attached (by plug-ins) through a new method on "resource"
  • method that adds an assertion to resource
    • checks to see if the assertion exists, uses if exists, creates if not exist
    • populates assertion with data

• • method that gets all the assertions from resource
• associate each custom metadata field with a URI-namespace to avoid cardinality
• Create plug-in; call from aggregate step; use resource's save method;

Deferred until later

Allow configuration of plug-ins

• enable/disable individual plug-ins
• add additional or custom plug-ins
• alter order in which plug-ins run (to determine which are authoritative)