I have to face the following scenario. It's no nice, but it is, as it is^^
There is a main application, which does XSL Transformation, using Xalan. Adminstrators are able to upload XSL Templates for specific resources. If user requests a resource, the main application loads and transforms it, using the admin's templates for this resource.
Now, there is a request for extended functionality of the XSL Templates (e.g. cipher jobs etc.). So, the administrators should be able to upload java libraries for the xsl templates, too. Their classes should be called by the XSL Template.
It is possible do java calls from xsl templates, using xalan. But how can it be achieved, that the XSL engine has access to the uploaded libraries? Can this be done with classloaders or osgi? I'm very so sure about this. Hope you can give me some hints.
How it works depends on the engine. Since you say it does it then it should have docs somewhere explaining it.
As a side issue you might want to consider the source of this additional functionality. If it comes from you no problem but if it is coming from someone else (like the customer) then you might want to spin up another process to handle this. That way it can't take down your server no pollute your process space.