The first Linked Data principle advocates using URIs as names for things - references to real world objects and abstract concepts, instead of just documents. These may include tangible things such as people and places, or things that are more abstract, such as topics and events.
We use the term Entity to represent a type (or class) of those objects. In the sense of an entity-attribute-value model, an entity is synonymous with the Subject of an RDF Triple.
The bibliographic records that make up WorldCat represent manifestations of items found in collections around the world. The metadata in those records include references to a vast number of entities (works, people, organizations, topics, places, and events). We are mining that metadata to extract those references and create rich descriptions of the objects that they represent.
Experimental WorldCat Linked Data
In June 2012, OCLC made the WorldCat.org bibliographic metadata experimentally available in linked data form. This is most often referred to as the WorldCat Linked Data. There is a one-to-one relationship between each record in WorldCat and each of those linked data descriptions.
Going forward, the linked data being released will represent the entities found in WorldCat and will link to the original record-level linked data descriptions.
The release of WorldCat Works is the first step in an evolutionary journey to provide interconnected linked data views of those entities. A Work is a high-level description of a resource, containing information such as author, name, descriptions, subjects etc., common to all editions of the work.
Mining all of the records in WorldCat is not a simple task, even to just identify works. It takes time, and a significant amount of [Big Data] computing resources. One of the key steps in this process is to identify connections, where they exist, between works and authoritative data hubs, such as VIAF, FAST, LCSH, etc. In this early release, some of those connections are not yet in place.
What you see in their place is a temporary link to what can be described as a local authority. These are exemplified by what the data geeks call a hash-URI as its identifier. http://experiment.worldcat.org/entity/work/data/2283978583#Topic/social_change, for example, is such an identifier, constructed from the Work URI and the person name. Over time, where the information is available, you can expect to see this link replaced by a connection to another entity or authority.
Using the data
For syndication purposes, the WorldCat entities will be published using a vocabulary that is based upon Schema.org and extended with other terms as needed.
The data is live, the URIs are persistent, and it is available under an open data license (ODC-BY).
WorldCat and others will start to use WorldCat Work URIs, and their descriptions, as a stable foundation for building out a web of relationships between other entities published. Over time, OCLC will be releasing other entities from WorldCat like Person, Place, Organization and Event. We expect that this web of data will stimulate both the sharing of other data and innovation in the design of applications and interfaces that are consuming the data.
We are actively seeking feedback on these efforts. Please Email us with questions or take some time to provide us with feedback. Your comments, suggestions, and critiques will help inform our activites as we continue to make more entities available.