Processing Distributed Data using XSLT, JavaScript, and Java: Advanced Data Services

You can use WorkSpace Data Federation to generate a data service, or you can write your own data service using Java, XSLT, or JavaScript.

Any data service can process data from one or more sources of these types:

Files (which can be generated views)
External web services
Other data services
Database operations or virtual database operations

You can invoke data services using JDBC or SOAP calls, or as input to other data services and view generators. A data service accepts runtime parameters, which can be routed to the input sources or to the data service plug-in. The output can be in rowset, XML, or raw byte stream format; output may also include parameters.

Data services perform their processing in a data service plug-in. A data service plug-in can be implemented as an XSLT style sheet, as JavaScript, or as Java classes (packaged in a JAR file). When you use WorkSpace Data Federation to generate and deploy data services, the plug-ins are generated as JavaScript. (When you use this method to create a data service, you might never see the plug-in—WorkSpace Data Federation creates and manages it for you.)

Use a different set of tools to write your own data service plug-in using XSLT, Java, or JavaScript. The style sheet, JAR, or .js file you create must be shared into the data catalog. Writing a custom data service plug-in, rather than creating a view model, makes sense when you are working with nonrelational data.

Another reason you might choose to write a custom data service plug-in is to use distributed transactions. When you need a set of database operations that write to multiple databases to be treated as a single transaction—that is, all must succeed, or if any fail, all must be rolled back—you can write a Java plug-in that uses the two-phase commit protocol, then set up a data service that calls all the database operations.

For instructions on writing custom data service plug-ins, see the Data Federation Provisioning and Advanced Data Integration Guide, part of the DI Suite documentation set, which is available on the Sybase Product Manuals Web site at http://sybooks.sybase.com.

In the default access control scheme, data services must be configured by members of the DataProviders group.