Just as the universal server war is cooling down, the battle for application servers is getting hot. Vendors are beefing up application servers with the capability to perform complex transactions over the Internet or intranet by effectively marrying databases to the World Wide Web. Rather than forcing users to build it all by hand, these software packages deliver the benefits of three-tier applications: thin clients and a flexible architecture that can scale.

In a three-tier architecture, the application server is the middle tier that holds the business and application logic necessary to support complex Web transactions. Typically an application server runs in tandem with a Web server, the other crucial part of the middle tier. A database on the back end and a thin client, usually just a browser, on the front end complete the three-tier structure.

Several vendors, including Oracle, Sybase, and Microsoft, are boosting the connectivity middleware that links Web servers to databases with development tools and object request brokers (ORBs), while the universal server pioneers IBM and Informix are espousing a database-centric approach.

"Neither Informix nor IBM has articulated how they would present an application server," said Judy Davis, an analyst at Database Associates, in Lexington, Mass. "It's the classic trade-off between flexibility and management. If you put everything [such as application-logic objects] into the database, you get great management, but lose flexibility."

And managing flexible connections to databases over the Internet is what it's all about when it comes to making the Web a viable place to do business.

"The key is how you move database transaction and state management functionality out into the middle tier," Davis said.

One company hopes to build an entire business by concentrating on this emerging market. Kiva Software is a 2-year-old start-up that hopes to grab the high end of the application-server space, while the more established database companies are struggling to compete.

The Kiva Enterprise Server supplies a set of services, including dynamic load balancing, transaction management, and multithreaded and multiprocessing management. Developers can use the Kiva software developer's kit, Java, C, or C++ to add application logic to the Windows NT or Unix server. Kiva plans to add Visual Basic support by the end of the year.

On the front end, Kiva's server supports standard browsers, Java, or ActiveX applications. On the back end, the Kiva Server can talk to most databases, including MVS data engines and transaction-processing (TP) monitors such as IBM's CICS.

"We are looking to the enterprise where you need to support 100,000 or more users," said Sharmila Shahani, director of marketing at Kiva, in Mountain View, Calif.

Indeed, some of Kiva's biggest customers are transaction-hungry telecommunications companies such as Pacific Bell and Hong Kong Telecom.

Market-savvy Microsoft is also getting into the game with Microsoft Transaction Server (MTS). Rather than take on mainframe-class applications, Microsoft is touting the ease with which programmers can create server-based three-tier applications.

MTS combines a TP monitor, ORB, and application-development environment. MTS supports hundreds, rather than thousands, of users, but Microsoft plans to win the hearts and minds of developers with easy-to-use rather than industrial-strength tools. Other products that aim to better scale Windows NT, such as Microsoft's Wolfpack clustering software and Message Queue Server due this summer, will eventually make MTS more useful for enterprisewide applications, according to James Utzschneider, lead product manager for MTS, in Redmond, Wash.

Of the big-three database companies, Sybase perhaps stands to gain the most in this market as it recreates itself as a connectivity vendor. The Jaguar Component Transaction Server is Sybase's middle-tier connection. Jaguar allows developers to use standard components, including Java Beans, ActiveX components, and CORBA objects, to build and deploy applications that manage online Web transactions.

"This is flexible management for synchronous and asynchronous transactions over the Web," said Gary Steele, vice president of middleware at Sybase, in Emeryville, Calif.

Currently in beta form, Jaguar is scheduled for release later this year.

Oracle sees the application-server space as just another piece in its ambitious Network Computing Architecture.

"Our Web Application Server is a Web request broker and a Web server that work with specific application cartridges," said Magnus Lonnroth, principle product manager in the Internet Server Products Group at Oracle, in Redwood Shores, Calif.

Application cartridges are CORBA objects that encapsulate data and methods required for specific transactions. Like Sybase and Netscape, a key piece of Oracle's Web Application Server 3.0 is CORBA ORB middleware licensed from Visigenic Software. Netscape's object-based application server will debut early next year with the company's Apollo.

The two other major database vendors, IBM and Informix, are taking a different approach to application servers, choosing to put the logic into their core database engines.

"The best three-tier architecture is the new two-tier one," said Jeff Jones, program manager for Data Management at IBM Software Solutions, in Armonk, N.Y. "Logic is stored in the database, as objects can communicate efficiently with the database. We push the middle tier into the database."

This is all part of IBM's Universal Database strategy. Specifically, developers write DB2 Extenders, or objects, that encapsulate new data types and associated methods, which become part of the database server. It is the encapsulated methods that contain application logic to perform complex Web transactions.

Informix is doing much the same thing with DataBlades, its object-extension technology for the Informix Universal Server.

Critics of this approach said pushing application logic into the core database engine makes the database less secure. Although there hasn't yet been wide-scale testing, IBM and Informix said their object-relational approach is stable and has the advantage of better performance through tighter integration with a central database server.

IBM, though, is hedging its bets. As part of its Network Computing Framework, IBM's Notes Domino server acts as both a Web server and a database that can hook into back-end CICS databases.

While the market chooses the right architecture, the explosion of the Web is positioning the application server front and center.

Building the perfect intranet

Two different ways to make the connection:

* Microsoft, Sybase, Oracle, and Kiva Software are putting application and transaction logic into separate servers.

Advantages: Flexibility and security

* Informix and IBM are counting on their object-relational database technology to store much of this logic in the database.

Advantages: Management and performance

Source: InfoWorld