Whatever your organization's needs, IBM probably has a WebSphere Application Server to meet them. But each level of the WAS V5 has significantly different pros and cons, so you need to take the time to get familiar with the features before you head off to "buy WebSphere."
To help you get a handle on the key differences of each, here's a look at the four levels of WAS.
WAS Express
This is the core of the WAS package, designed to be the lowest-cost, entry-level WebSphere package. Ideal for building dynamic Web applications, it's also a good base from which to conduct small pilot projects.
Express contains many of the development tools in WebSphere Studio, with a scaled-down version of WAS. Express supports the core J2EE standards such as Java Servlets and JavaServer Pages (JSPs). In keeping with IBMs focus on Web services, Express has extensive support for Web services standards including Simple Object Access Protocol (SOAP), Web Services Description Language (WSDL) and Universal Description, Discovery and Integration (UDDI).
Express is limited by the fact that it does not support Enterprise JavaBeans (EJBs), and also supports only a few database products, namely DB2 Universal Database, Informix, SQL Server, Sybase and Oracle, as well as DB2/400 on the iSeries platform.
Also, it comes with an embedded HTTP server, which is both convenient and limiting, since the embedded server can handle between 10 and 20 concurrent users as a general rule of thumb. You can't add an external Web server to expand that number either, as Express doesn't support external Web servers. Worse, for Domino shops, Express does not integrate with the Domino HTTP server, which seriously limits the integration between WebSphere and Domino.
But, again, for modest Web application or pilot projects or as a cheap way to put a toe into the WebSphere waters, this is a good version, and applications developed on it can be seamlessly moved to other versio...
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ns of WAS.
WAS Base
Otherwise known as simply the "WebSphere Application Server," this basic version builds on Express and is optimized for ease of administration for small and mid-sized environments.
For those of you familiar with WebSphere V4, the V5 Base edition is similar to V4 Advanced Single Server. Base extends Express with full support for the J2EE 1.3 platform -- including EJBs -- as well as for external HTTP servers -- such as Domino -- and a wider range of databases.
It also boasts a few enterprise-level features such as remote administration across firewalls, support for the Common Secure Interoperability (CSI) and Java Cryptographic Extension (JCE) security standards, as well as dynamic caching for better performance.
Its chief drawback is scalability. Aimed at implementations with between 50 and 100 concurrent users, the WAS Base runs on a single server and has limited scalability; it is therefore not suitable for mission-critical applications that must provide 24 x 7 x 365 uninterrupted service.
WAS Network Deployment
The Network Deployment version is for those of you that have mission-critical applications with a need for high-level features like load balancing and failover.
Similar to the WebSphere V4 Advanced Edition, the Network Deployment package takes the WAS Base package and adds on mission-critical features such as support for clustering, centralized administration, edge-of-network features such as HTTP load balancing and Web page caching for enhanced scalability, and high availability for distributed environments.
A key administrative feature you get at this level is the Deployment Manager, which manages all systems and applications servers in a distributed WebSphere network from a single workstation. The Deployment Manager can start and stop applications servers remotely, distribute configuration changes to other systems in the network and ensure that all systems are running the same revision level of WebSphere, which greatly improves the consistency and stability of operations.
Unlike previous versions of WebSphere, however, the administrator must dedicate a workstation to run the Deployment Manager for monitoring and managing the other WebSphere system in the network.
For organizations interested in forging ahead in Web services, this package supports UDDI registries and provides a Web Services Gateway so that users outside of the firewall can invoke Web services.
WAS Enterprise
Considering implementing WebSphere Commerce or WebSphere Portal? Require sophisticated business process interaction and workflow capabilities? Then you need the WAS Enterprise, recently renamed Business Integration Server Foundation.
This version, which includes all of the Network Deployment features, is aimed at large enterprise environments that need to create and support dynamic business process flows between multiple applications. To accomplish this, it includes proprietary extensions to the J2EE programming model, such as workflow and application performance enhancements. For instance, it includes
"asynchronous beans" to enable Java applications to parse a transaction or a process into parallel tasks, thereby speeding performance. The WebSphere business solutions, WebSphere Portal and WebSphere Commerce, are based upon Enterprise because they make use of these extensions.
WAS Enterprise also provides support the Business Integration Server Foundation supports the Business Process Execution Language for Web Services (BPEL4WS) standard.
One drawback to the Business Integration Server Foundation is the lack of portability that the IBM Java extensions create. Applications that make use of the extensions cannot be ported to other J2EE application servers. However, as long as you don't use those specific extensions, you can build and run your own applications in the Enterprise edition, and these applications will be completely portable.
Tony Higham is the chief solutions officer at FatWire Software and an expert on Lotus, WebSphere and Java technologies. He can be reached at tony.higham@FatWire.com.
Sue Hildreth is a contributing writer and editor based in Waltham, Mass. She can be reached at Sue.Hildreth@comcast.net.
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