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Designing and Programming CICS Applications by Members of the CICS Development Team at IBM Hursley, John Horswill

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Designing the Web Server Components

The web server’s job is to listen for requests for account details, validate input parameters, connect to CICS, pass on the request to the CICS application, format the returned data into HTML and return a web page to the user’s browser. All of these tasks can be handled by a special type of program running in the web server environment called a servlet.

Design for the Error page

Figure 8-4. Design for the Error page

In Chapter 9, we can divide the specific tasks further among three distinct components:

  • A Java servlet to process the request and connect to CICS

  • A JavaBean to temporarily hold information about the customer

  • Java Server Pages (JSP) to automatically format the returned data into HTML

Let’s look at these web server components in more detail.

The Java Servlet

The Common Gateway Interface (CGI) was one of the first practical techniques for creating dynamic content. With CGI, a web server can forward HTTP requests to an external program. The output of this program is then returned to the client browser. CGI is more-or-less platform-independent and is very popular. However, CGI has many drawbacks that affect web application performance and it is particularly resource-intensive. There are several proprietary solutions that work only on certain web servers, such as server extension APIs, Active Server Pages, and server-side JavaScript. These are by no means perfect solutions, ...

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