Version materialization options

[brechtvdv]

Materialize the persistent objects in an eventstream with a (latest) version

Use RSP spec with named graph to wrap the materialized object

[brechtvdv]

Version key metadata is required (TBD)

[pietercolpaert]

Two steps are needed for this to work:

1. Transforming 1 version of an object into the object itself. This is ready: https://github.com/TREEcg/version-materialize-rdf.js has been written
2. Filtering the stream so you can select the version you need

I think the latter should be part of a future feature, when LDES client is fully embedded in Comunica, to then just use Comunica’s SPARQL support to filter out the right version from the stream, and also adapt the source selection based on that (e.g., don’t follow relations that are certain to not give members).

Let’s already implement 1 in the LDES client and, for now, leave out the filtering to the LDES Client user.