Putting app servers to work

As more information technology shops embrace the distributed computing model, the idea of more tightly integrating middle-tier application servers with back-end databases becomes quite compelling.

Although there are substantial savings to be gained by using the distributed computing model, many federal agencies find that there are other benefits—such as shorter development times and increased reuse of software codes—to linking the distributed layers of their applications. But even though off-the-shelf products provide more built-in integration capabilities, agencies still face the difficult task of learning how to develop applications in this new environment.

The distributed, or n-tier (meaning any number of tiers), computing model usually includes at least three components. There is the front-end Web server that receives requests from users. The request is then handed off to one or more middle-tier servers, where it is acted upon by programs on the application server. The middle tier-based application server might then reference one or more back-end databases before sending the request results back to the presentation layer, such as a Web browser.

The benefit of this architecture is that it can support lots of users and data and can be adjusted over time as agency needs change.

But usage data from industry groups, such as IDC and Gartner Inc., shows that most IT shops use application servers primarily to support basic application and data integration. These include applications that use Java Server Pages and servlet technologies that might perform simple functions, such as obtaining a single record from a database.

Application servers—such as BEA Systems Inc.'s WebLogic, IBM Corp.'s WebSphere and Oracle Corp.'s Oracle9i—offer other, more advanced technologies that are not used as much as they could be. Those technologies include support for Enterprise JavaBeans, Extensible Markup Language (XML) and Web services such as Simple Object Access Protocol (SOAP) and Universal Description, Discovery and Integration (UDDI).

Agencies should examine those technologies as a way to support entire application systems in a cost-effective manner, said Jeff Jones, director of database solutions for IBM. For example, an agency can simplify electronic data exchanges with other agencies using XML, component-level application communication using SOAP or publish/subscribe functionality using UDDI.

IBM's DB2 relational database in turn is closely tied to the company's WebSphere application server via built-in support for those types of data exchanges and standards.

"The level of accessibility provided by native connectivity between WebSphere and DB2, coupled with WebSphere support for industry standards, such as XML, makes it worthwhile to consider [using them in] a distributed n-tier application architecture," Jones said.

Oracle's John Magee and Bob Shimp, both senior directors for the company's flagship database Oracle9i software, see other benefits to integrating application servers with back-end databases. "The integration supported by linking the two tiers increases security, as agencies can more easily support single sign-on," Shimp said. Security policies can be put in place down to the data row level or within a block of data.

"Agencies should also take advantage of the built-in analytics capabilities included in several of the application servers that are available," Magee said. "In addition, advanced options—such as clustering, load balancing and session-level failover .— increase the degree of application reliability and scalability."

An Army project is one recent example of the benefits afforded by linking application server technology with back-end databases. The organization is using the Oracle9i Application Server to build a programwide knowledge management system. The Army's knowledge portal will support 1,700 staff members and 39 combat service support and information systems programs within the Army's executive offices. Dubbed Adapa, after the Babylonian god of knowledge, the portal is expected to improve staff performance by automating workflow, creating better document management capabilities for data and archival materials and increasing the accessibility of Web-based data. The Army and Oracle's Consulting Services are constructing the portal.

"We find application server technology compelling because it allows us to more easily construct full-blown applications that can service the entire organization," said Hendrick Browne, an Army lead analyst on the project. "When compared to other technological meas.ures, we found this approach to be best for our project and have been happy with the reduction in costs and the fact that we can implement independent of the hardware."

But moving to a distributed application architecture isn't always easy. Agencies will need to adjust to a new way of building and maintaining applications. However, once learned, the ability to rapidly deploy applications that are highly secure yet easily linked to agency data can yield substantial time savings.

"Agencies will need some time to get their arms around" this new application model, Jones said. "Constructing distributed applications that take advantage of database and application server integration requires an application- assembly view of the world. Developers will need to hook together the common parts of applications, and the degree of code reuse will increase over time."

Agencies that have used legacy client/server technologies have typically had to design, develop, test and deploy each application from scratch. By reusing common application logic in a component-based approach, agencies can construct new applications much faster.

And the importance of XML in this context cannot be understated. "XML is the single underlying technology that provides the tight integration between applications and data," Jones said.

Aside from thinking about applications in a new way, there are other challenges. "Agencies will likely struggle with translating existing user and transaction workload" to this new model, Shimp said.

But that's no reason to delay preparations. "Planning how you will mesh your new architecture with [mainframe or client/server] legacy applications will allow the agency to more easily adopt this new application" model, Magee said.

As the worlds of application and data become tightly linked, some industry analysts expect that application servers will soon reside inside databases or within operating systems.

But officials at IBM and Oracle say they do not see any benefits to that approach. "The level of integration already afforded to agencies via existing application server and database linkage is substantial, and moving the application server inside the database will yield little additional benefit," Magee said.

IBM's Jones and Oracle's Shimp say there is another approach that does provide added value. "Agencies should consider application servers that are provided as part of a hardware vendor's" products, Jones said.

Shimp added, "Hardware vendors that offer [products] that marry databases and application servers have typically tested these configurations closely, and these providers can go a long way toward helping agencies implement solutions in a much shorter timeframe."

Biggs has more than 15 years of business and IT experience in the financial sector.