Java Servlet Programming

JavaServer Pages

Just as this book was going to press, Sun announced a new way to use servlets, called JavaServer Pages (commonly, but not officially, referred to as JSP). JSP’s functionality and syntax bear a remarkable resemblance to Active Server Pages (ASP).

JSP operates in many ways like server-side includes. The main difference is that instead of embedding a SERVLET tag in an HTML page, JSP embeds actual snippets of servlet code. It’s an attempt by Sun to separate content from presentation, more convenient than server-side includes for pages that have chunks of dynamic content intermingled with static content in several different places.

Just like server-side includes and servlet chaining, JSP doesn’t require any changes to the Servlet API. But it does require special support in your web server. This support is not included in the Java Web Server 1.1.1 (the unofficially considered reference servlet engine against which this book is written), but it’s expected to be introduced in the next version of the Java Web Server, probably 1.2, and in other servlet engines as they keep pace.

Note that the following tutorial is based on the JavaServer Pages draft specification, version 0.91. You may notice small changes in the final specification.

Using JavaServer Pages

At its most basic, JSP allows for the direct insertion of servlet code into an otherwise static HTML file. Each block of servlet code (called a scriptlet) is surrounded by a leading <% tag and a closing %> tag.^[10] For convenience, ...