Thus, we smoothly integrate the functionality already existing on the WWW for searching documents with our extensions for searching over the metadata associated with sources. Once relevant data sources have been found, the same language provides access to the data. The Data Source Layer has two components, data sources and wrappers . Data providers create and manage collections of autonomous data sources , that can be accessed over the Internet. These data sources can provide query capability ranging from full DBMS functionality to simple scanning of files.
WS assumes uniform access to both kinds of sources, independent of the capability of the sources.
This may be accomplished using wrapper components. The second layer is the World Wide Web Layer . The WWW is used as a medium for describing and publishing sources. Thus, in order to publish a data source, a provider needs to create a WS-XML document describing the source. The third layer is the Catalog Layer .