More companies are using Web services to expose the data in their legacy applications to browser-equipped servers, mobile devices and other new types of systems. But this is a relatively new endeavor, one that's been explored by only a handful of companies to date, and it's not necessarily a good idea for those just starting out with Web services.
Still, it can be worth the learning curve. Going the Web services route can make a company's mainframe-based, business-critical data available to a newer generation of hardware and software -- without the company's having to completely revamp the older systems. It also allows companies some time to determine if and when the legacy applications have run their course and need to be retired or substantially rewritten, all the while saving the information residing within those applications.
Jim Keohane, a Search390.com site expert and president of the New York consulting company Multi-Platforms Inc., says that XML is very common as the tool of choice for wrapping mainframe applications as Web services, while Simple Object Access Protocol (SOAP) is "less so, but is catching on."
Pierre Fricke, executive vice president at consultancy D.H. Brown Associates Inc., in Port Chester, N.Y., says "it's a fairly leading-edge area, and more people are looking at it than doing it" at this point. He calls the legacy area an "advanced" case of Web services, and says that most existing SOAP-based tools, as
More tools are coming to the market. In March, Unisys Corp. announced a new generation of mainframes that incorporates its Distributed Transaction Integration (DTI) middleware; this software allows customers to wrap mainframe applications as J2EE .NET objects. DTI comes as a standard piece of software in all of Unisys' Dorado machines.
Along the same lines, IBM Corp. recently debuted SOAP for CICS, which allows customers to encapsulate CICS-based applications as Web services via SOAP. IBM will eventually build this technology into its core CICS products, but it's still considered a technology "preview" at this point, available for free download from IBM's AlphaWorks Web site.
Products from the established mainframe players "make sense if you have investments in those technologies" that you plan on keeping for the long-term, says Ron Schmeltzer, senior analyst with consultancy ZapThink LLC, in Waltham, Mass. But if you have older technology and are not looking to upgrade, it might make more sense to go with an independent software vendor for Web services help.
Some names here include established middleware vendors WRQ Inc., in Seattle; iWay Software, a subsidiary of Information Builders, in New York; and Tibco Software Inc., in Palo Alto, Calif., among others. Then there are companies targeting the Web services-based integration space, including Instantis Inc., in Sunnyvale, Calif., and those that are specifically going after the ability to tap into legacy systems with a variety of technologies. Vendors in this last camp include Attachmate Corp., in Bellevue, Wash.; Iona Technologies, which has U.S. headquarters in Waltham, Mass.; Seagull Software Systems Inc., in Atlanta; and HostBridge Technology in Stillwater, Okla.
While few experts deny the benefits of bringing a Web services approach to legacy applications, some sound danger knells, too. First, the place to start with Web services is not the mainframe. Start smaller, and then attack the mainframe data when everyone involved is up to speed on object-oriented lingo and concepts, as well as on SOAP or XML, or whatever other tools may be used.
Second, security and transaction speed and integrity may be issues to confront. Security is an especially big concern if mainframe data is being exposed as a Web service to run on the Internet.
Third and most important, mainframers "need to grok the entirety of their applications and assets" and then craft a Web services approach that gets the job done in the best way possible, Keohane says.
In other words, don't assume a one-for-one relationship between a Web service and a legacy system. There might be a better way to approach it. Let's say an insurance company needs to view all of its claims information. This is a requirement that can touch on multiple mainframe applications, and perhaps the best way to approach it is to meld data from three of the old applications and package that together as one Web service.
"Don't stick with the old architecture," Keohane advises. "Think of new ways to approach old
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This was first published in June 2003