Web services fans in chorus: “The WS-I Basic Profile is here!”
- By Jack Vaughan
Web services are intrinsic to the architectural plans of Microsoft, IBM and other vendors. At the same time, they are key to development teams that want to see better interoperability between applications from Microsoft, IBM and the rest of the world.
For many, it is has come time to move from proofs-of-concept to real applications.
Web services using XML, WSDL, SOAP, messaging, RPCs and other means have been white-boarded and prototyped almost to death in the last two years. As modest- and moderate-scale projects have begun to go live, the nitty-gritty issue of how well this stuff actually interoperates has -- not surprisingly -- raised its head. Efforts of the Web Services Interoperability (WS-I) Organization to address this issue have borne fruit recently with the release of important implementation guidelines for developers.
It took about a year to create the Basic Profile 1.0, said Chris Ferris, senior software engineer at IBM. “That’s pretty much how long it takes to cook this kind of document,” he noted. Included in the profile are guidelines for the use of specifications such as SOAP 1.1, UDDI 2.0, HTTP, ANT and WSDL 1.1 -- the last element being both a rallying point for interoperability and, sometimes in the early going, a locus for flaws.
For each element (UDDI, SOAP and so on), there is guidance as to how to use the underlying specification, as well as clarifications. “Until now,” said Ferris, “the language was frequently misunderstood.”
A software engineer curious about the inner workings of standardization might ask how the work of the WS-I relates to the SOAP and WSDL standards work going on in Tim Berners-Lee’s W3C organization. A lot of standard proposals must be considered there.
The WS-I, said Ferris and other WS-I colleagues, tries to focus on immediately practicable problems. “The people at the W3C are not looking at validating implementations,” said Ferris. “But by looking at what the WS-I does, they can see what people care about. Not everyone wants interoperability, but the WS-I is into interoperability.”
He added that the Basic Profile reduces the amount of choice facing developers, “and that’s a good thing.”
In the early days of any standard, a spec may look like a square peg to one vendor, and a round hole to another. “Now people can say ‘The WS-I says it’s a round hole, and we are going with that,’ rather than create one-to-one mappings with every vendor’s solution,” said Ferris. At issue, too, are the intersections where elements like SOAP and WSDL play together.
The profile tells you when you are using vendors’ tools in such a way that they will work with other vendors’ tools, he said. Without such a guide, and with the multiple aspects of vendors’ tools that developers must work with, development efforts can mistakenly run into some unwanted bleeding-edge work.
Beyond this profile and other upcoming profiles, WS-I has worked to create sets of sample apps that are all available from the organization’s Web site. Also part of the effort: use cases and usage scenarios that sound a bit like so-called software patterns, and from which the samples were derived. The group has also sponsored a series of “jam sessions” that show Web services in action, such as the showcase demonstration staged in August at the XMLOne Web Services Conference and Expo in Boston.
Once Web services are working, the next challenge is to ensure interoperability so that one group within an organization can promote its Web services to others in the same company or beyond, suggested Bill Stangel, senior vice president and enterprise architect at Fidelity Investment Company.
“Interoperability is everything to us. Data is everything. We want to get out and advertise [our Web services for use] beyond a single app,” said Stangel, who attended the Boston conference. “Web services give us and our business partners that common language.”
The WS-I Profile means that Fidelity does not have to completely invent Web services interfaces and face the risk of having “thousands of developers trying to go in the same direction,” said Stangel.
“The Profile is a huge thing going forward,” he said, as it forms the starting point for test cases and prototypes.
A next big step for WS-I is to take the profile -- written in “English prose” -- and turn it into a set of testable assertions. Some such WS-I tools are already in beta. Test vendors, including Mindreef and Parasoft, have also begun to adapt their tools to work with the Basic Profile 1.0.
For more on this topic, please go to www.ws-i.org.
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Jack Vaughan is former Editor-at-Large at Application Development Trends magazine.