With a corporate ad slogan extolling "It's everywhere you want to be" and a payments network that indeed serves nearly every country in the world, you can bet Visa IT executives feel the onus of availability and reliability.

Hiccups simply can't be tolerated when 14,000 financial institutions count on your payment-processing system for more than $1 trillion in annual transaction volume. That's 5,546 payment-transaction messages per second, or 100 million transactions a day, on average. (During the most recent December shopping frenzy, Visa's message gateway handled 9,200 transaction messages per second.)

Placing that volume in context can be difficult, says Sara Garrison, senior vice president of network and open systems development at Visa, in Foster City, California. But think about this, she says: "If you take all the transactions across all the stock markets and exchanges in the world, and you aggregated them over a 24-hour period, we do that volume over a coffee break."

Needless to say, Visa doesn't make infrastructure decisions lightly. But the company does push boundaries and rapidly adopts technologies that could benefit Visa member banks, the merchants they serve and, ultimately, consumers holding the 458 million Visa-branded cards in the U.S. This doesn't mean the company embraces technologies on the high-risk bleeding edge, Garrison says. But it usually finds itself on the leading edge -- which makes it well worth watching as it ventures into use of new data center technologies.

Take Visa's evolution toward a services-oriented architecture (SOA) and use of Web services. Like many companies, Visa has long recognized the inherent value of services-centric application development. But Visa leapt ahead of most companies by extending Web services to business partners.

As of late last year, Visa uses Web services to allow direct communication between its back-end systems and those at member banks involved in the charge-dispute process. Visa already used Web services internally for this industrial-strength dispute management system, called Resolve OnLine. A mammoth undertaking that involved 150 developers working concurrently for nine months to meet the first release date, this industry-reference Web application for development projects is now in its fifth-generation release. Created by Visa developers using Java 2 Platform Enterprise Edition (J2EE), Mercury and Rational tools, in conjunction with IBM's WebSphere Integrated Application Suite, Resolve OnLine automates the dialog across back-end systems so disputes could be quickly resolved, Garrison says. Extending Web services to member banks enabled Visa to streamline the process further.

Prior to Resolve OnLine, which went into production in June 2002, cardholder disputes had to be processed on paper. Visa couldn't easily automate the process because of the differing back-end systems and legacy specialized-functionality tools in use throughout the industry. By using Web services, Visa and member banks have eliminated many of the remaining manual processes involved in dispute management. For example, back-end systems at Visa and member banks now can communicate directly regarding requests for transaction research, dispute case search and retrieval, and requests for copies of original paper receipts. Visa secures the inter-enterprise Web services transactions via Secure FTP sessions over SSL.

Since implementing Resolve OnLine, not only has dispute transaction length been reduced but also the number of disputes has diminished. "The inquiry capabilities have lessened the number of issues that come to dispute, and we have seen resolution time cut roughly by one-third," Garrison says.

In 2004, Resolve OnLine saved issuers $52 million in operating costs, while member savings from the reduction in volume of exception items exceeded $300 million during the year, she says.

This Web application is a natural extension of Visa's open systems goal of ensuring that code can be "componentized, encapsulated, compartmentalized, replaced and reused"easily, Garrison says.

Visa readied itself for a Web services SOA by building applications out of self-contained piece parts, and using J2EE to ensure independence from back-end hardware and operating systems. Following best-practices guidelines to ensure scalability, robustness, security and extensibility also has helped. For example, Visa has embraced the Open Management Group's Unified Modeling Language and IBM's Rational Unified Process for configurable software development and automated testing of code.

"We're seeing viable reuse, leading to rapid product delivery," Garrison says, citing development of an Internet file gateway service in three months as one example. Almost half -- 47 percent -- of components used for that service came from the Resolve OnLine code base.

Visa now uses Web services in its new application development projects. Already, about 10 percent of Visa's internal applications have Web services components, Garrison says, and continued extension outward is an absolute must.