If you want to deliver dynamic content for your Web site, you must integrate an application server (to process server-side scripts) into your Web site delivery strategy. For sites that use JSPs, you can take advantage of 4GL extensions to the Web Target object model. The 4GL JSP page interface can handle many of the coding details for you.
For information about 4GL JSP pages, see Chapter 9, “Developing 4GL JSP Pages.”
For non-4GL Web site targets, you can write scripts that directly target an application server using the object model specific to that server, such as the Active Server Pages object model. However, you can also write platform-independent code using the Web Target object model (without the 4GL extensions). If you want to deploy Web site targets to more than one application server platform, you need to write your server scripts in JavaScript, which is supported by ASP (as well as by most client browsers).
For 4GL and non-4GL JSP targets, you write server-side scripts in Java, although you can still use JavaScript for client-side scripting. You can also use the JSP implicit object model in your server scripts.
For more information about the implicit object model, see “Implicit objects”.
An application server processes code on the server system before a Web server sends a page to a Web browser. By taking advantage of the capabilities of an application server, you can include conditional execution, looping, and other programming structures in your Web pages.
Application servers process template or source files to return dynamic content. The server evaluates server scripts when the page is requested and generates the HTML page, which it sends to the client browser.
For an overview on how application servers fit into an integrated Web delivery environment, see Chapter 1, “Working with Web Targets.”
A dynamic page is a page that is generated each time it is accessed. Using application servers to create dynamic pages helps you enhance your Web site. Dynamic Web pages can:
Respond to input from a browser, returning data requested by the user.
For example, a user can complete a form on a Web page, then view another page in response to data entered on the form.
Customize the output for each user.
After a user provides information on a Web page (such as areas of interest, or level of expertise), the content delivered to the user’s browser can be fine-tuned to the information provided.
Customize the output for the display capabilities of the Web browser.
Different page presentations can be generated based on the type of browser a client uses to access the Web site.
The template for a dynamic Web page typically provides all of the following content before and after processing by an application server:
Template contents before processing |
Contents after processing |
|---|---|
HTML-encoded text |
HTML-encoded text |
Embedded Web DataWindows or database queries with instructions for formatting the retrieved data |
Formatted database information |
Server-side scripts |
Results of execution of server scripts |
Client-side scripts |
Client-side scripts |
Users do not see the unprocessed template page in their browsers. They see the page content after the application server processes the template page, and after their browser processes client-side scripts.
When you are working with a Web target, you can create template pages in two ways:
4GL Web pages provide an event-driven infrastructure that lets you create JSP pages with dynamic content easily. The Web Target object model extensions that underlie these pages handle many of the coding details required to produce dynamic pages.
For more information about 4GL JSP pages, see Chapter 9, “Developing 4GL JSP Pages.”
Server-scripted pages let you create all of your own server scripts. The Web Target object model provides a number of server objects that you integrate into your scripts. Other server-side object models are available for deployment to specific server types.
Pages you deploy to Active Server Pages, to your file system, or to more than one platform, require manual coding for server scripts without recourse to the automatic coding (for parameter binding and page data management) available with 4GL page templates.
For more information about writing server scripts without the 4GL Web page technology, see “Working with server scripts” and “Managing page data”.
