LDF requests and processors

[hartig]

This PR provides the main meat of my refactoring efforts. The functionality related to i) parsing LDF requests and ii) processing such requests is separated out into new interfaces and classes, and the use of these classes is integrated into the existing code base.

[mielvds]

Nice @hartig , this brings us closer to the flexibility LDF is about. The datasource package is kind of crowded though, let me propose the following: all LinkedDataFragment classes => org.linkeddatafragments.fragments all TriplePatternFragment classes => org.linkeddatafragments.fragments.triplepattern Perhaps move the servlet class and remove the servlet package.

org.linkeddatafragments.ldf or org.linkeddatafragments.tpf could also be possible, less scalable though.

[hartig]

OK. I will move the classes as you suggest and add the commits to this PR.

[RubenVerborgh]

Full :+1: on this!

[hartig]

@mielvds Done! Ah .. hold on ... I just realize how ugly org.linkeddatafragments.fragments.TPF as a package name is :-( Will rename to org.linkeddatafragments.fragments.tpf Just a sec.

[hartig]

@mielvds OK, done now. (Note that I also added source-specific subpackages in org.linkeddatafragments.datasource)

[mielvds]

Merged! Thanks again. I'll do some minor changes and put out a new release. I'll also rebase the jena-3 branch

[hartig]

@mielvds Please wait with the release. I am thinking about a way to make the servlet more generic; i.e., removing the current assumption that the request is a TPF request.

[mielvds]

will do

[hartig]

Another thing that would be really good to have for what I am planning is to have this server as a Maven artifact (in an online Maven repo).