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From Kin-Man Chung <Kin-Man.Ch...@Eng.Sun.COM>
Subject Re: [PROPOSAL] jasper2 detection of compile time page include changes
Date Wed, 24 Apr 2002 18:29:21 GMT
+1 on the idea.

With minor changes, we can also implement a compiler server that compiles
out-of-date pages in the background thread.  This would greatly improve
the response time for accessing the pages, when recompilations are needed.

> Date: Wed, 24 Apr 2002 10:52:51 -0500
> From: Glenn Nielsen <glenn@voyager.apg.more.net>
> Subject: [PROPOSAL] jasper2 detection of compile time page include changes
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> 
> A common problem Tomcat users have is that Jasper does not detect when
> a compile time included file <%@include file="..."%> changes so that
> it can recompile dependent JSP pages.  This propsoal maps out a possible
> solution for this.
> 
> Create a new class (JspDependency) which is used to store mapping of JSP 
> pages to dependent compile time included files.  This class will be 
> created for each web application context and the data it depends upon
> serialized to a special file in the work directory on context stop,
> and read from that file on context startup.  Proposed filename is
> JSP_DEPENDENCY.ser.
> 
> Here is how this integrates into Jasper:
> 
> On context start instantiate a JspDependency object and read in the
> dependencies from JSP_DEPENDENCY.ser.  If there are dependencies,
> start a background thread which checks for changes in compile time
> included files once each 5-15 minutes. Perhaps make this configurable.
> If changes are detected, set flags for dependent JSP pages which are 
> affected.  Using a thread to accomplish this rather than having JSP 
> Load do the dependency checks should reduce the request latency 
> overhead for detecting these changes.
> 
> The JSP Load method will call a method in JspDependency to determine
> whether the current page needs to be recompiled due to dependency changes.
> This will just be a quick test of a boolean, actual dependency checks
> are done by the background thread.
> 
> The JSP page compiler will call a method in JspDependency to remove all
> dependencies for the current JSP page on compile start, then call an
> add method for each compile time include dependency found.
> 
> After a JSP page compile has completed any changes to dependencies
> are written back out to the JSP_DEPENDENCY.ser file.
> 
> Comments or suggestions?
> 
> Regards,
> 
> Glenn
> 
> ----------------------------------------------------------------------
> Glenn Nielsen             glenn@more.net | /* Spelin donut madder    |
> MOREnet System Programming               |  * if iz ina coment.      |
> Missouri Research and Education Network  |  */                       |
> ----------------------------------------------------------------------
> 
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