Corporate.Net Web Middleware Glue Binds Web Apps By Barry Nance   Web middleware is the software "glue" used to build large-scale Web-enabled applications and systems. By large-scale, we mean applications deployed on several database servers, which thousands of clients can access via multiple Web servers. In such a complex environment, you want application programmers to concentrate on rendering business logic in their computer programs. You don't want them spending a lot of time creating and maintaining Tinker Toy-linkages within the network infrastructure of the application's various servers and clients. To view the Report card. Web middleware can manage interactions among tiers in Web-based apps with a three-tiered (separate presentation, business logic and data storage) architecture. You need industrial-strength middleware to handle certain functions, such as load-balancing, security, dynamic routing and multiple dat abase access. For instance, if one database server is down, middleware can queue the SQL request and deliver it when the server comes back up, or it can reroute the message to an available server. Meanwhile, other databases are updated without delay. Similarly, middleware can route HTML and other Web traffic to less busy servers, thus shortening response times. Web middleware understands and works with Web servers, HTTP and browsers the way ordinary client/server middleware works with file servers, transport protocols and fat clients. Because the distribution of work (transactions) within a large, complex Web application is probably the biggest problem that middleware can solve, we focuse d on middleware products that provide load-balancing and dynamic routing in a Web-based environment. Middleware should be easy to incorporate into the application, yet help the application process transactions through their entire life cycles. Five vendors supplied us with Web-enabled middleware products: BEA Systems' TUXEDO and Jolt, IBM Corp.'s Transaction Server, KIVA's Enterprise Server, Microsoft Corp.'s Transaction Server and Visigenic Software's VisiBroker. Our test environment consisted of a network with 50 desktop computers, which were connected via 100-Mbps TCNS fiber network from Compaq Computer Corp. We used Microsoft Windows95, IBM OS/2 and Apple Computer Macintosh clients (35 computers), along with Windows NT and OS/2 servers (15 machines) to exercise these products. We weren't looking to determine the load point beyond which these products would fail. Instead, we examined each product's ability to support multiple platforms; provide useful, easy-to-implement features to a networked appl ication; distribute application workload; and react to the dynamic addition or removal of both servers and clients. With its multiplatform support, mature heritage and many features, BEA's TUXEDO rose above the competition in our evaluation. TUXEDO's transaction-monitoring functions work extremely well, and its servic e directory feature (a naming service for application objects) is a big plus for overworked network administrators. TUXEDO's support for several diverse programming languages and databases ensured its lead over the other products. Our testing proved that TUXEDO is easily the most capable and well-rounded Web middleware product for complex, networked applications. IBM's Transaction Server, with its support for legacy applications (middleware should require as few changes in existing programs as possible) and wealth of complementary products (such as MQSeries), finished a close second. To download an Adobe Acrobat .pdf format version of the Web Middleware feature charts, click here.

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