Sunday, 1 January 2012

Web Service Data Sources (Virtual Table Support)

To access data (returned from single or multiple Web service invocations) through a database table, create a virtual table through a Web service data source. This table function allows you to query a set of returned rows as though it were a table.

The client invokes a Web service and the results are stored in a virtual table in the database. You can pass result sets from function to function, allowing you to set up a sequence of transformation without a table holding intermediate results. To reduce memory usage, you can return the result set rows a few at a time within a function.

By using Web services with the table function, you can manipulate a range of input values (from single or multiple Web services) as a real table. In the following example, the inner SELECT creates rows whose columns are used as arguments for invoking the CALL_WS Web service call-out. The table expression could be used in other SQL queries, for constructing views, and so on.

SELECT <some-columns> 
 s FROM <some_table>))),

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