Viewing WISs as Database Applications.

In the article, authors say that although Web information is meant to be consumed by human beings, applications that process it automatically are both conceivable and desirable. A useful abstraction for modeling these problems is to view the Web as a collection of, usually small and heterogeneous, databases, and to view programs that extract and process Web data automatically as database applications. WebOQL system, developed at the University of Toronto, is a tool for building the software layer through which such programs can view Web data in a uniform, convenient format and can effectively manipulate it using a declarative query language. In WebOQL, every data source is logically viewed as a graph of trees where every arc in a tree or graph is labeled with a record. The mapping between a data source and this logical view is performed by wrappers dynamically, as queries are executed. WebOQL queries can be embedded in Java programs like SQL queries are embedded in C programs.