|Re: Newbie questions - please help me understand [message #1630587 is a reply to message #1630141]
||Mon, 23 February 2015 09:15
| Zoltan Ujhelyi
Registered: July 2015
thanks for your interest in EMF-IncQuery. About the applicability of alternative persistence layers, the answer is both yes and no.
In theory, the query engine of EMF-IncQuery can be executed over any EMF Resource/ResourceSet implementation, including DB-backed ones. However, the selected algorithms assume that the model is available in the memory, thus building an index from the contents of the resources is possible. This, for large, DB-backed models this might require a large amount of memory and/or might be expensive in runtime.
On the other hand, we are actively working on alternative approaches that supports such instances. One of these is a local search based query engine that does require less indexing (if any at all), thus is capable of handling larger models (of course with very different performance characteristics). An initial implementation is already available from EMF-IncQuery 0.9.0, and a more integrated version is planned to be included in a few days (and be generally available in EMF-IncQuery 1.0.0 planned for this June).
In EMF-IncQuery 0.9.0 we also made an effort to loosen the dependency on the IncQuery engine on EMF Resources and Resource sets by the introduction of different query scopes. Although this feature is originally planned to support different modeling implementations such as RDF or MPS, it also allows adding specialized indexing algorithms for dedicated DB-backed resource implementations. Such alternative implementations are under active development, but are not (yet) available from the EMF-IncQuery project.
Finally, we are working on another approach called IncQuery-D, that reuses the query engine(s) of EMF-IncQuery in a distributed environment, where the indexes are allocated over multiple computers, thus greatly extending the size of models that can be handled by the different algorithms. For this reason, see our Models 2014 paper "IncQuery-D: A Distributed Incremental Model Query Framework in the Cloud" (http://scholar.google.com/scholar?q=IncQuery-D:+A+Distributed+Incremental+Model+Query+Framework+in+the+Cloud).
I hope, I was clear enough; if not, or you have further questions, feel free to ask for clarification.
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