Web-Based Enterprise Computing

ecently, Web technologies have emerged as a credible alternative to client-server computing in corporate enterprise. Using information extracted from any ODBC-compliant DBMS and delivered over the Net, today's Web applications are moving from static HTML pages to full interoperability with corporate databases. Java, COM, CORBA, and related technologies (see sidebar, " Related Web Programming Technologies ") are driving this shift in application design. Web-based enterprise computing allows corporate IT to integrate disparate systems into a single, coherent environment. This shift from a traditional Web server with database connectivity to integrated systems that support the use of Web technologies facilitates business processes and allows corporations to service both internal and external customers effectively. First-generation Web-based applications for enterprise computing typically use a traditional client-server architecture with CGI programs (often Unix shell scripts, C, and/or Perl programs). To develop a Web interface for an existing database, we can simply write a CGI database script. This script is an external program run by the Web server to access the database and create output in the form of an HTML document, which is then presented on a Web client. This is a proven architecture, but it has several major limitations: • Difficult to maintain state and session connection • Performance bottlenecks can occur • Can involve proprietary APIs • Limited extensibility and robustness • Lacks end-to-end security features These limitations can create significant problems when trying to develop enterprise based Web applications. An alternate architecture is to do away with the Web server (and possibly the OS as well) and simply add HTTP function-ality to the database software. As shown in Figure 1, this approach allows Java applets running in the browser to make calls directly to the database, eliminating the overhead of the Web server. The downside of this design is poor security since you are allowing anyone with a Web browser and a connection to the network to interact directly with your database. In addition, most Java applet-to-database programs are likely to be proprietary code, limiting portability. Using JDBC with Java servlets to replace CGI is a different architecture that not only solves typical client-server problems, but also gives code portability and allows your server-side application to interface with a wide range of rela-tional databases. A servlet, coined in the same context as the Java applet, is a small program that runs on a server. Java applets, usually intended for running on …