ResourceManager access in a processor in a servlet listener pipeline?

I'm working on integrating the Java API of WURFL (
http://wurfl.sourceforge.net ) into an OPS application. Because the
WURFL datafile is a fairly large XML document, I decided to write a
servlet context listener pipeline to initialize the Java WURFL tools at
server startup time. I now have running code, but in the process, I had
to work around a lot of difficulty in writing a custom processor to go
in that pipeline. I'm hoping someone here can tell me a better way.

The WURFL Java tooling looks for its datafile (wurfl.xml) and an
optional patch file (wurfl_patch.xml) in only a few places - by default,
only /WEB-INF/ of a webapp, or /tmp/. I wanted to be able to put the
datafiles anywhere I wanted, which means that I have to initialize WURFL
by handing it InputStreams for those two files. (Unfortunately, the
WURFL api won't accept a stream of SAX events.)

I configured OPS to run the pipeline processor at servlet startup, and
wrote a custom processor to be run inside that pipeline. I wanted to be
able to read "oxf:/" URLs from the procesor's configuration, something
like this:

<p:processor name="my:wurfl-init-processor">
   <p:input name="config">
     <config>
       <wurfl-loc>oxf:/data/wurfl/wurfl.xml</wurfl-loc>
<wurfl-patch-loc>oxf:/data/wurfl/wurfl_patch.xml</wurfl-patch-loc>
     </config>
   </p:input>
</p:processor>

I couldn't get this to work, though, because I couldn't find any way to
get a ResourceManager within my custom processor, and thus, I had no way
to resolve "oxf:/" URLs. I tried several different ways to initialize
ResourceManagerWrapper, but I could never get it properly initialized.

I finally had to do something like this (heavily abridged) in my processor:

public void start(PipelineContext context) {
   Document config = readInputAsDOM4J(context, "config");

   String wurflLoc = config.valueOf("/config/wurfl-loc");
   String wurflPatchLoc = config.valueOf("/config/wurfl-patch-loc");

   ExternalContext externalCtx = (ExternalContext)
           context.getAttribute(PipelineContext.EXTERNAL_CONTEXT);

   ServletContext srvCtx = (ServletContext)
           externalCtx.getNativeContext();

   File wurflFile = new File(srvCtx.getRealPath(wurflLoc));
   File wurflPatchFile = new File(srvCtx.getRealPath(wurflPatchLoc));

   // and then open InputStreams and pass them to WURFL
}

This means that I have to use webapp-relative paths in my configuration:
 
<wurfl-loc>/WEB-INF/resources/data/wurfl/wurfl.xml</wurfl-loc>
 
<wurfl-patch-loc>/WEB-INF/resources/data/wurfl/wurfl_patch.xml</wurfl-patch-loc>

That's not unworkable, but I'd rather be able to take advantage of the
extra layer of indirection provided by the "oxf:/" protocol. Also, it
means my processor has an explicit dependency on the Servlet API.

So, finally, the question: Can anyone tell me how I can get access to my
ResourceManager from within this processor?

Thanks for reading through such a long email. Any suggestions would be
greatly appreciated.

Jeff Jones
The Weather Channel Interactive



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Jeff,

Try:

   ResourceManager resourceManager = ResourceManagerWrapper.instance();

 From there, you can call several methods, including getting an
InputStream, a SAX stream, etc.

-Erik

Jeff Jones wrote:


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