I keep stumbling into porting issues when moving older servlet applications from Jrun or Servlet Exec to Tomcat. A couple issues related to directory structure always seem to arise.
One issue is that an application expecting all servlets to be loaded from a single classpath may not have the 'context' prefix. For example, an application 'app1' that posts to '/servlet/Controller' may not work unless 'app1' is defined as Tomcat's default context. It would work if you change the code so that it posts to 'app1/servlet/Controller'. But that's a global change that hardcodes the context name.
Incidentally, I observed the same issue when changing the 'appbase' in Tomcat's server.xml - the Tomcat home page is no longer accessible. Even if you create a new 'tomcat' context, the admin, manager and servlet examples linked from Tomcat's homepage don't work. A solution I found works in Tomcat 5 is to create new contexts for each, such as:
<Context path="tomcat/servlets-examples" docBase="c:\apps\java\tomcat\webapps\servlets-examples" debug="0" />
As I recall, this didn't work in Tomcat 4.
Another issue is that 'context' seems to function as both a 'script-alias' and an 'alias' for static files, but with differing results. For example, suppose that in the application called 'app1', I create a static web page that does 3 things:
- displays an image at 'app1/images/button.gif' - loads a stylesheet from '/app1/includes/default.css' - posts a form to '/app1/servlet/Controller'
It seems that the images and includes folders are expected to appear in the folder 'app1' directly below my appbase, whereas the Controller servlet is expected in the 'app1/WEB-INF/classes' folder. This is different from where these folders resided in other servlet containers that did not use 'WEB-INF'. Apparently 'app1' is a 'script-alias' for servlets, and an ordinary 'alias' for static files, with different meanings for each. The problem can be resolved if I use a connector to Apache or IIS, and then create the 'alias' for static files in the web server. But in a standalone instance of Tomcat there is no separate alias definition - 'context' is the only way to create aliases.
- Am I right about the double-meaning of 'context'?
- Do others experience similar porting issues?
- Is there an online guide that helps app developers select a directory structure that is portable across servlet containers?
- Finally, is it the best practice to hard-code the 'context' prefix in your application?
Cheers.
Regards, Bill Claxton [EMAIL PROTECTED]
OpenAsia Solutions provides streaming media & payment solutions.
Check out http://www.openasia.net
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