[JBoss-dev] Jasper problems - Eureka !

[Jules G. <jul...@ya...>]

I was giving Jasper and all the related unpacking problems some thought
in the car on the way home this evening and reckon I have a nice, simple
solution to all our woes (and Tomcat's, if they are interested...).

Jasper supports pluggable compilers.

We simply write a ResourceBasedCompilerAdaptor Compiler.

This has 3 main features :

1. it understands URLs on it's classpath. Any non-file: URL is treated
as a resource available to
Thread.currentThread().getContextClassLoader(), copied into a cache, and
replaced on the classpath with a file: URL to the copy.

2. when looking for the .java file that it is being asked to compile, as
well as looking in the file system, it will try getting the file as a
resource from Thread.currentThread().getContextClassLoader(), copying it
into the same cache and substituting the original filename with a new
one pointing to the copy.

3. It wrap-n-delegates to the actual required compiler - javac, jikes
etc. Which may then painlessly compile away, oblivious to the fact that
it is running in a resource based, rather than file-based, environment.


Anyone see any problems ?

I reckon that with this, we can forget all those painful unpacking
problems, whilst still being able to run apps that are already unpacked,
with no overhead.

At the same time the code maintains compatibility with future versions
of Jasper (unless they change the compiler API) whilst having no
dependencies on ServletContainer or AppServer.

Lastly, a URL->file cache may come in useful for local caching of remote
resources, if JBoss or Jetty does not already contain one......

Before you ask, I haven't given any thought to timing out the cache, but
it should be possible to check the date on the remote resource shouldn't
it (do I need 1.4 to do this?).

Jules



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