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https://issues.apache.org/jira/browse/GIRAPH-170?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13257695#comment-13257695
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Paolo Castagna commented on GIRAPH-170:
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Hi Benjamin
> I call this the RDFAdjacencyCSV
We came to the same conclusion. I ended up using Turtle for this, as explained
here:
http://mail-archives.apache.org/mod_mbox/incubator-giraph-user/201204.mbox/%3C4F84872E.4050101%40googlemail.com%3E
Turtle isn't splittable in general, but it can be made so simply writing all
the RDF statements with the same subject on a single line.
> I would like to say that Paolos suggestion of providing some ready made code
> for Pig, HBase and MapReduce for processing RDF sounds like a really great
> contribution.
I am not sure what's the best place to put such code, I started with sharing
small examples and experiments on GitHub, here:
https://github.com/castagna/jena-grande
> Integration of RDF reasoning capabilities: I will need to perform subclass
> reasoning on the DBPedia graph.
See Apache Jena's RIOT infer command or a MapReduce version of it, here:
https://github.com/castagna/tdbloader4/blob/master/src/main/java/org/apache/jena/tdbloader4/InferDriver.java
I wonder if Giraph could be used to implement the RETE algorithm
(http://en.wikipedia.org/wiki/Rete_algorithm) which is what Jena uses (with in
memory RDF Jena models).
> Workflow for loading RDF graph data into Giraph
> -----------------------------------------------
>
> Key: GIRAPH-170
> URL: https://issues.apache.org/jira/browse/GIRAPH-170
> Project: Giraph
> Issue Type: New Feature
> Reporter: Dan Brickley
> Priority: Minor
>
> W3C RDF provides a family of Web standards for exchanging graph-based data.
> RDF uses sets of simple binary relationships, labeling nodes and links with
> Web identifiers (URIs). Many public datasets are available as RDF, including
> the "Linked Data" cloud (see http://richard.cyganiak.de/2007/10/lod/ ). Many
> such datasets are listed at http://thedatahub.org/
> RDF has several standard exchange syntaxes. The oldest is RDF/XML. A simple
> line-oriented format is N-Triples. A format aligned with RDF's SPARQL query
> language is Turtle. Apache Jena and Any23 provide software to handle all
> these; http://incubator.apache.org/jena/ http://incubator.apache.org/any23/
> This JIRA leaves open the strategy for loading RDF data into Giraph. There
> are various possibilites, including exploitation of intermediate
> Hadoop-friendly stores, or pre-processing with e.g. Pig-based tools into a
> more Giraph-friendly form, or writing custom loaders. Even a HOWTO document
> or implementor notes here would be an advance on the current state of the
> art. The BluePrints Graph API (Gremlin etc.) has also been aligned with
> various RDF datasources.
> Related topics: multigraphs https://issues.apache.org/jira/browse/GIRAPH-141
> touches on the issue (since we can't currently easily represent fully general
> RDF graphs since two nodes might be connected by more than one typed edge).
> Even without multigraphs it ought to be possible to bring RDF-sourced data
> into Giraph, e.g. perhaps some app is only interested in say the Movies +
> People subset of a big RDF collection.
> From Avery in email: "a helper VertexInputFormat (and maybe
> VertexOutputFormat) would certainly [despite GIRAPH-141] still help"
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