Taming Web services
- By John Moore
- Mar 23, 2003
Like flowers in an untended garden, Web services are blooming freely but without much order.
Web services mark industry's latest push to get disparate applications to communicate with one another. The software development concept uses standards based on Extensible Markup Language as the common framework through which software components can interact. Proponents say the approach has widespread support among software developers — something earlier integration visions lacked.
In recent months, Web services have begun to sprout in the federal sector. Examples can be found at the Defense Information Systems Agency, the Environmental Protection Agency and the U.S. Postal Service, among other government entities. And Web services may grow in popularity, especially since the Office of Management and Budget is encouraging agencies to use XML when developing their e-government projects.
So far, so good. But something is missing from the Web services mix: structure. Yes, standards are in place, but developers may interpret them in different ways. The task of orchestrating multiple Web services is another difficulty. Web services management, in general, is a topic industry leaders have only recently begun to address.
This state of affairs is fine for the current crop of relatively simple Web services, but problems arise when organizations pursue more sophisticated deployments.
"I think that Web services are ready for certain applications in the federal government," said Brand Niemann, a computer scientist at the EPA and head of the CIO Council's XML Web Services Working Group.
But he said it's a different story when it comes to applications that require high levels of security or are transaction- oriented. "Agencies are not ready culturally, nor are we ready technically, to do all that," he said.
That said, standards bodies are addressing issues that inhibit the widespread adoption of Web services. Product vendors are working on the problem as well, including a number of start-up companies and heavyweights such as IBM Corp. and Microsoft Corp.
Web Services on the Rise
A Web service is an application that exists as a URL-addressable Internet resource. The concept rests on four core protocols: XML, Simple Object Access Protocol (SOAP), Universal Description, Discovery and Integration (UDDI) and Web Services Description Language (WSDL).
XML provides the common language of Web services, bridging the differences between disparate applications and operating systems. SOAP, an XML-based protocol, is the messaging portion of Web services, enabling one application to request and receive data from another. UDDI lets organizations advertise their Web services, while WSDL provides an XML-based format to describe them.
The Web services approach was initially envisioned as a means of producing innovative Web-based applications. Today, industry and government executives cite integrating applications and revitalizing legacy systems as the key benefits.
An older application, for example, can be "wrapped" in XML and become more readily accessible as a Web-enabled software component. The EPA has taken this approach with its facilities database, which now features a Web interface through which data can be extracted in XML format.
XML's ability to transcend different platforms, operating systems and programming languages makes Web services a powerful interoperability player, adherents contend.
Indeed, interoperability is the goal of Wizard XML, a Web service that USPS officials hope will streamline business mail processing. With Wizard XML, a postage statement form — used in bulk mailings — can be filed electronically and transferred to the Postal Service's PostalOne database through XML. Conquest Systems Inc. developed Wizard XML, which is running as a limited prototype.
"We hooked up PostalOne with any software a mailer could be using to compute a postage statement," said Pedro Olympia, Conquest's chief technology officer.
The Web services concept also makes life easier for portal developers who want to tap a variety of information sources. Officials at the National Institutes of Health have begun using Web services in this fashion, noted Charles Mokotoff, technical lead for NIH's portal. "It's fairly easy to go ahead and have information [from a given application] displayed on someone's portal page," he said. NIH uses portal technology from Plumtree Software Inc.
Need for Structure
Developers and users have yet to push Web services to their full potential. Olympia said Wizard XML uses XML and SOAP for messaging, but does not employ UDDI because the tool doesn't need a directory of services that would call for that component.
However, the ultimate vision of Web services involves a registry of software components that can be discovered via the Web and then linked together to perform various tasks. Web services of that complexity would require the full suite of core protocols. They would also require more in the way of security, business processes and management infrastructure.
As for imposing order on Web services, even the core protocols could stand some tightening. Web services promise greater interoperability among systems, but may not be interoperable themselves if deployed inconsistently.
With that in mind, the Web Services Interoperability Organization is developing a guide for developers who use Web services standards. The organization's Basic Profile 1.0 covers XML, SOAP, UDDI and WSDL and is intended to clear up ambiguity — the use of words like "may" vs. "must" — in the various specifications, said John Kiger, director of Web services strategy at BEA Systems Inc. BEA, IBM and Microsoft are among the founding members of the group.
Basic Profile 1.0 is currently a working draft, but the organization expects to deliver a final guide in late spring.
Beyond foundation protocols, security is a key consideration in Web services. As work continues on specifications such as Web Services Security, other developments are under way in Web services coordination and management.
Coordination becomes critical whenever multiple Web services are drawn together to accomplish something. Bob Sutor, director of Web services technology at IBM, said the key question is this: "How do I coordinate multiple Web services that have to succeed as a group?"
Such complex, transaction-oriented Web services require a level of business process maturity thus far lacking in the Web services world, observers say. One gap is the ability to ensure that a transaction successfully updates all appropriate files in a distributed environment, a process known as "two-phase commit." That feature is standard in traditional transaction-processing environments.
"It's a part of the transaction-processing world" and enterprise application integration, said Larry Calabro, the partner in charge of Web services at Deloitte Consulting. "But Web services need to get there, too."
Industry leaders, however, are working on a number of specifications to put Web services on a firmer transactional footing. Web Services Transaction, for example, aims to group multiple Web services into a single, logical transaction, according to Mark O'Neill, chief technology officer at Vordel Ltd.
Web Services Coordination coordinates the activities of distributed applications and works in conjunction with WS-Transaction. Another specification, Business Process Execution Language for Web Services, is designed to extend Web services to support business transactions. IBM, Microsoft and BEA announced those three specifications last year.
Still, Niemann believes a few years will pass before federal agencies can go to a registry and link several Web services together in real time.
On the management side, existing systems and network management products are being pressed into service to handle Web services. Management tools such as IBM's Tivoli software can manage a Web service the same way it handles any other application, Sutor said. Some longtime management vendors are releasing Web service versions of their products. Candle Corp., for example, recently debuted Omegamon Web Services, said Pete Marshall, assistant vice president for data center management at Candle.
Meanwhile, a number of Web services management start-ups have emerged, including Adjoin Inc., WestGlobal and Talking Blocks Inc. Company leaders believe they can provide a level of management beyond what traditional products can accomplish.
"Traditional systems management vendors...only tell the health of the box and large-scale applications on the box," said an Adjoin spokesman. "They can't provide a view of the interaction between Web services components." The company plans to target the government sector with a management product scheduled for general availability in the second quarter of 2003.
Don LeClair, a senior vice president with Computer Associates International Inc., said the emerging Web services management vendors provide an "intermediary approach. This means they manage the Web services 'on the wire,' not in the underlying application server." CA, in contrast, manages Sun Microsystems Inc.'s Java 2 Enterprise Edition application servers and Microsoft's .NET Framework, which LeClair calls the leading platforms for writing and deploying Web services.
Although it appears that both camps have a role to play, some market watchers believe the traditional management vendors will eventually hold sway. Analysts at ZapThink LLC, a Waltham, Mass., market research firm, contend that the start-up management vendors have a two-year window before larger, more established vendors dominate the market.
That two-year span could see Web services go from simple Web-enabled applications to elegantly linked software components. But there's work to be done before the true potential of Web services is revealed.
Moore is a freelance writer based in Syracuse, N.Y.