How to debug asp pages

JSP opens up possibilities for server-side scripting solutions

Because it effectively combines the power and cross-platform nature of Java with the ease of development associated with server-side scripting, Java Server Pages is truly a brilliant technology.

Scripting has taken the Web by storm because it is easy to deliver dynamic content via server-side scripting environments like Microsoft Active Server Pages (ASP) and Netscape Server-Side JavaScript (SSJS). Scripting languages like JavaScript and VBScript have been, up until now, the only languages available for server-side scripting in these environments. ASP has been especially popular because an ASP solution is much easier to develop than a CGI/PERL solution.

Although JavaScript and VBScript are good languages and are complete in many areas, they are lightweights in comparison to a full-blown object-oriented language like Java. When you use JSP, you leverage Java's many strengths, like JDBC, Java Beans, Java Applets, Java Servlets and the Java class libraries. Are you coming from an environment like ASP? Do you know a little or a lot of Java? You are probably going to find JSP easy to use.

What is JSP? JSP is server-side .scripting technology for dynamic content delivery. It uses Java as the scripting language and can easily use Java components like Java Beans that encapsulate business processes.

What is so important about JSP? First and foremost, JSP lowers the barrier of entry for developers. Previously, in order to deliver content in a dynamic fashion, it was necessary either to develop the solution with a Java Servlet - requiring a higher level of developer skills - or to use a platform-specific technology like ASP. JSP makes every Web developer normally confined to client-side scripting instantly capable of writing server-side scripting solutions.

JSP also leverages the best of the cross-platform capabilities of Java. No longer is a server-side scripting solution tied to a specific solution. What works well on Windows NT will work equally well on Linux, Sun Solaris, HP-UX and even mainframe systems. Imagine that: big iron enterprise machines pumping out dynamic Web content with JSP.

How JSP works

JSP and ASP are very similar. Undoubtedly, the creators of JSP took advantage of what had been previously developed for ASP. As a result, a developer who is familiar with ASP will have no problem doing JSP instead.

JSP works by processing a jsp file before delivery of the content occurs to a Web client. The file will typically look like a mixture of HTML content and server-side scripting, with the server-side scripting identifiable by special tags denoting that the code within is to be executed on the server, e.g. Here's a simple "Hello World" JSP code example:

One distinguishing characteristic of JSP is the processing that occurs on a JSP page. The first time that a JSP page is processed, a conversion occurs that takes the JSP page, does a just-in-time compilation on it, and generates a Java Servlet. Compared to a pure scripting solution, one can imagine the performance benefits that result from JSP's ability to automatically generate compiled code from scripting code. The previously generated Java Servlet will service all future requests received by the Web server for this particular page.

Working with isp

The current publicly released specification for JSP is 1.0, although two previous specifications - 0.91 and 0.92 - are also available. The next JSP specification, now in public draft form, will be 1. 1. Day by day, more and more resources become available on the Web with information about JSP.

Because JSP is brand new, cutting edge technology, not many development tools are available for it. Editor support, however, is built into IBM's Websphere product via collaboration with Elemental Software's Drumbeat 2000, and Allaire has editor support in HomeSite.

Probably the biggest challenge that JSP developers currently face is presented by the lack of a debugger for JSP. This is the one thing that can make JSP development difficult. When server-side script debuggers become available for JSP, they will be very, very hot!

In all fairness, however, I should point out that it is possible to debug Java Servlets with products like Symantec's Visual CafI6 and IBM's Visual Age Java development environments. Doing this requires an extra step, of course, in that a compilation of the server-side scripting code must occur in order to create the Java Servlet.

Getting started

Before getting started with JSP development, you have to make sure that JSP support is currently installed on your Web server. Even if the Web server you are using does not have JSP support directly, there is still hope. A number of products, available for free evaluation or as freeware or shareware, can enable JSP support on your favorite Web server/operating system platform.

Is JSP for you? If serving up dynamic Web content to users on your Internet or intranet is important, and you would like to leverage the strengths of a robust object-oriented language in your server-side Web development, plus you want to make implementation easy for your development teams, then JSP is for you. In addition, being able to work with a nonplatform-specific server-side scripting solution means that applications can run on a multitude of platforms.