Service-Oriented Architectures Peter Varhol Product Manager, Compuware Columnist, Java Pro June 7, 2004

About Peter Varhol Web application columnist for Java Pro –Numerous articles for Web Services Journal, Dr. Dobbs Journal, XML, Byte, and others Former college professor and department chair in computer science and mathematics Graduate degrees in computer science and applied mathematics Compuware product manager for developer products

Delivering on the Promise of SOA Loose coupling among interacting software agents –Data and logic become separated Reduce (though not eliminate) dependencies among components Making applications extensible means they can adapt –New versions are easier to build... –While still constraining the design

The Web Service is Not Just Another New Library Might be a different platform –Java,.NET, or mainframe Rarely local to the application –... Or even the enterprise It may do multiple tasks –Check the status of a shipment –Issue shipping authorization Rarely static –The interface only may stay static; or –Query the WSDL

Architecting a Successful SOA Technical challenges are significant –But not the biggest issue More than just building web services –Services that support existing business practices –While enabling new ones to be implemented rapidly The latter is the hard part –Anticipating future application needs –Must be tied into corporate strategy activities Steps to building an effective SOA

Know the Business The concepts behind business processes, yes But also the mechanics –What are the steps involved and why are they important –It helps to have designed some of the processes involved Why? –What parts of the process can be packaged as a service –How users and client applications will interact with that service –How a service might be useful in the future

Understand the Mechanics of Web Services Interfaces –SOAP –WSDL Components –Listener –Façade –Business logic –Data access

Narrow Down the Candidates Consider these questions: –Is this basic function used across multiple business processes? –Can it be generalized enough to serve multiple roles? –Is it discrete enough to run efficiently and not add complexity to the application architecture? –Can it fully operate without manual intervention? –Is it likely to be useful in future business opportunities? Choose a small set of candidate Web services based on these considerations

Implement a Candidate Web Service Initially build one or two Web services –Get experience in applying the technology –Use these services as a test bed Put that Web service into production Collect data –Times called, by which client applications –Uptime and response statistics Feed back results into SOA plans

Understand How SLAs Fit In Run it with real users Support it when real users are counting on it Collect data –response time –Scalability –Reliability Project that data across an entire SOA Does it meet SLAs for availability and capacity?

Work Around Existing Successes Understand why existing services work Apply those principles to expanding the SOA

The SOA and Enterprise Strategy

Summary SOA has the potential to improve and accelerate application development –While making applications more robust and extensible But only if the application can count on its services for performance and scalability Service consumers can help –By testing the service with their application –By analyzing and diagnosing problems within the context of their application