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Jasper is an engine which executes HTML-templates with Java code within.
In other words, Jasper is yet another Java-based engine to run JSP pages.
We say now 'JSP'-pages, though in times when Jasper was born, the JSP technology did not exist.
In other words, we were programming in JSP when there were no Tomcat yet. Parallely with us were developed GJP - Gnu Java Pages. That was the only similar product on the market at that time.
First version of Jasper was developed by Scand in 1998-1999. At that time we were looking for a technology which can help us to create Web-based applications in a best way. After evaluating such technogies as PHP, Perl, ASP, we didn't find them satisfying enough for our goals. For example, many of our porjects had to be cross-platform (running on OS/390 and Solaris as well). We wanted a technology that will allow to write the code directly in HTML and provide enough features and flexibility for the future enhancements.
Common concept was basically taken from ASP. In HTML file can be written blocks of executable code in Java programming language. These blocks are parsed by Jasper interpreter, compiled (if needed) by Java Compiler and executed by Java Virtual Machine. All blocks with executable Java code are separated from HTML by placing them between reserved tags ‘<%’ and ‘%>’.
Besides, Jasper offered a set of basic useful for a Web-application classes, such as Session, Application, and a few other, for example a Schedule class.
Later, when Tomcat appeared on the market, we nevertheless continued development of Jasper. The main purpose for that was - we have control over this app (i.e. can maintain it) and so we have more flexibility. Many interesting features were added, such as:
own API to write custom plug-ins for specific needs
own class loader mechanism, allowing to control on loaded classes
a possibility to put applications in an archive (yes, similar to WAR)
own command-line compiler, that allows to compile the whole app at once
original plug-ins for internationalization purposes (they automate translation procedure)
Many our clients are still (as for November 2003) using Jasper! Now the reason for it become another subject: now Jasper is much faster than Tomcat and requires less memory and resources for execution! It runs under any version of JVM (starting 1.1) and provides most of basic features that Tomcat and Resin provide.
We are still continuing further development of Jasper. Now targeted are:
XML-compliance. Jasper pages can be written fully in XML, with custom tags and template libraries - i.e. completely according the modern standards.
automatic tool for obfuscation. Many customers are developing commercial applications on Jasper, and they don't wish to provide their products with source code; they also are afraid of the possibilty to decompile their app. For this purpose we include a tool that allows to obfuscate resulting archives in a specific way, which not only includes standard obfuscation procedures, but also on Jasper processing stage decrypts parts of code.
Although Tomcat and Resin are more advanced tools, we believe that Jasper has future.
It's always nice to have an alternative, and Jasper is it.
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