InformationWeek: The Business Value of Technology

Managing state requires that developers implement a mechanism to track the status of the transaction at every point in the user session. According to Axys Solutions' Guthrie, developers typically opt for one of three ways to capture and pass state information: URL rewriting, cookies, and hidden HTML fields.

URL rewriting is a technique in which a small amount of state information is attached to the URL each time the user clicks on something new. The benefit of URL rewriting is that every browser supports it. However, you can only save minimal information, and URLs can grow unwieldy.

Cookies, small packages of information stored by a Web site on a user's machine, might be the most popular method of managing state. Developers can put a lot of information into cookies, but cookies require at least tacit cooperation from users. For privacy reasons, many users have disabled cookies on their browsers, which makes them problematic.

Finally, an application can embed a session identifier in a hidden HTML field and pass that information to the application server. The application server matches up the session identifier and tracks the state of the user's session. This requires considerably more processing at the server, and while developers can capture a fair amount of state information in hidden fields, it can make pages large and slow to load.

Books24x7.com Inc. in Norwood, Mass., which provides access to the full text of books online, takes a different approach to state management. The company caches session-oriented data in objects on a Web server and manages those objects through state information passed to and maintained on its SQL Server back-end database, says VP of engineering Doug Jenkins. "We then use stored procedures to complete the transaction or roll it back," he says. The drawback, he says, is that the caching eats up memory, which can affect scalability. The company's developers also use Active Server Pages and session cookies to manage state in other parts of the application.

As Web technologies mature, developers are finding solutions to some of their other challenges as well. For example, to solve its significant Web-to-legacy system integration challenges, People's Bank developers turned to a middleware solution based on various IBM messaging technologies. Now, Guidone says, "the developers just need to write a call that says 'get customer' and sends the right parameters. The application then returns the right information."

Atlantic Mutual, for its part, has resolved the problem of transaction integrity in complex multisystem transactions by employing a combination of messaging, queuing, and batch updating. Winn found that asynchronous communications can be useful for less time-sensitive transactional processes. "Often, pieces [of data] aren't essential right at that moment," Winn says.

Similarly, InfoGain's Chen says he will store transactions for later processing while the application proceeds in real time, recording what happens without committing the transaction. In the worst case--a transaction failure--the system generates a message to the customer alerting him or her to a system problem.

The task of building Web-transaction applications keeps getting easier. Technologies such as Enterprise JavaBeans and Microsoft Transaction Server take care of much of the low-level transaction processing, says the Standish Group's Boucher. Prebuilt components and transaction frameworks can further speed the process, adds David Norris, senior manager of architecture for consulting firm USWeb/CKS Corp. Norris built a Web application using IBM's Net.commerce and reusable Java components for bedding maker Pillowtex Corp. to feature its Royal Velvet and Fieldcrest product lines. Similarly, Delta Capital Technologies Inc., a software-development company, leveraged components from IBM's San Francisco program, Java, and WebSphere to build an oil and gas industry trading application that handles transactions for dozens of vendors, operators, and contractors. "It will even offer online, real-time bidding," says Kevin Wong, Delta Capital's VP of technology.

The phenomenal growth of the Web, with analysts' E-business projections running into the trillions of dollars within the next few years, suggests that many companies' developers are quickly mastering the art of building transactional Web applications. Are yours?

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Illustration by Doug Ross
Photo of Jenkins by Shelly Harrison