Semantic Web Programming

Chapter 9. Combining Information

"Words, so innocent and powerless as they are, as standing in a dictionary, how potent for good and evil they become in the hands of one who knows how to combine them."

—Nathaniel Hawthorne

Pieces of information, like the words of a sentence, are more useful and powerful when they are combined effectively. One of the major use cases in the Semantic Web involves virtually integrating information from multiple disparate sources. This process of integration can be decomposed into two primary steps: bringing data into a common data model (in the case of the Semantic Web, RDF) and describing the data using a common knowledge model. Once combined in a common data model, the aggregate information can be accessed and manipulated in a single model; however, the data is still described using different vocabularies. For data to be fully integrated it must be combined into a common data model and described using a common knowledge model.

As an illustrative example, consider two disjoint databases, each with a single table and a unique schema. One maintains the inventory at a store, and the other maintains records for the transactions made at that store. Combining these sources (as depicted in Figure 9-1) could be as simple as merging the two databases, each with a single table, into one database with two tables. By combining the data, it becomes a common data model and representation, the tables of a relational database, but the two sources are still disjoint conceptually. ...