Servlet now completely agnostic of the type of LDFs requested

[hartig]

As promised in #18 (comment), this PR provides everything to make the servlet completely agnostic of the type of LDFs that the data source supports.

[mielvds]

It probably shouldn't be called TriplePatternFragmentServlet anymore I guess. Aren't you tying everything to the datasource now?

[hartig]

@mielvds You are right; it really is a LinkedDataFragmentServlet now. I will rename it and push a commit into this PR.

@RubenVerborgh I know; I am also only "medium-happy" with it. But, as you say, it is already quite an improvement over the existing, TPF-only focused implementation approach. Moreover, note that the actual implementations of the IDataSource interface do not have to deal with the HTTP requests because this is already covered by AbstractRequestProcessorForTriplePatterns. Another thing that I should emphasize in this context is that AbstractRequestProcessorForTriplePatterns uses the intermediate method createFragment(String, String, String, long, long) on purpose. This can be overridden in request processors / data source implementations that are not based on Jena and, thus, it allows for avoiding the overhead of having to i) generate Jena objects and ii) transforming them into some other representation that the backend understands (e.g., Sesame objects).

[RubenVerborgh]

@hartig I'm more than medium happy 😉 Great job!

[hartig]

@mielvds OK, renaming done.

@RubenVerborgh ;-)