SCA and SDO: Standardizing SOA-based apps

Two specifications are helping developers navigate the stormy waters of SOA implementation; Service Component Architecture (SCA) and Service Data Objects (SDO) are two ways vendors hope to simplify the process.

"SCA gives developers a new and better way to weave disparate SOA services together into a SOA-style application.  To a lesser extent, it also helps with the creation of each individual SOA service component," says Roy Schulte, Gartner's vice president of application integration and middleware analysis. "SDO does for data in a SOA application what SCA does for service components─it abstracts the developer's view of the data in an effort to simplify the design and maintenance of data-handling application functions."

The SCA and SDO specifications can simplify the creation of new architecture and transform existing IT assets, enabling reusable services to meet changing business requirements. These specifications reduce complexity associated with developing apps by unifying services regardless of programming language and deployment platform.

However, Schulte cautions that SCA is incomplete and immature. "Companies should understand what it does and evaluate it for possible future inclusion in their SOA strategy, as part of their standard methodology for developing SOA applications," he suggests. "Those who understand what is in SCA will have a good understanding of what is missing in today's SOA development tools.  By mid 2007, SCA will probably be polished enough to provide tangible benefits to leading edge companies developing SOA applications."

According to Schulte, two of the three major app vendors (SAP and Oracle) support SCA. The third, Microsoft, does not support SCA, but supports a similar concept in its new Windows Communication Foundation─a part of the Vista and upcoming Longhorn server operating systems.

In a March report, Gartner Research VP Jess Thompson, wrote, "One of the most important aspects of SCA is that it establishes a foundation for a standard notation for expressing a standard set of concepts for specifying service-oriented architecture."

Before SCA, developers could build SOA apps in Java and other languages, but had to use relatively low-level programming interfaces to connect the service consumers and service provider components to each other, Schulte says. And because there was no systematic way to represent the relationships between the components, configuring and maintaining large SOA apps with many components was complex.

"Essentially, SCA provides a new, metadata-centric way of designing a SOA application at a higher level of abstraction, which should make SOA applications easier to build, maintain and change," says Schulte. "It helps that SCA supports multiple different programming languages and its run time implementations will run on different application servers and different operating systems."

Vendors initially came together to work on such specifications in late 2005. BEA Systems, IBM, IONA, Oracle, SAP AG, Sybase, Xcalia, Zend, Cape Clear, Interface21, Primeton Technologies, Progress Software, Red Hat, Rogue Wave Software, Software AG, Sun Microsystems and TIBCO Software are the seventeen organizations involved─and what Gartner calls most of the major players. Together, they have developed SCA and SDO technologies, including new and updated draft specifications.

About the Author

Shawna McAlearney is a senior web editor at Application Development Trends. She can be reached at [email protected].