Hi Stephan, thanks for the response. Unfortunately I'm not familiar with the new Gelly APIs and the old Spargel ones (I still don't understand the difference actually). Do you think it is possible to add such an example to the documentation/examples?
Best, Flavio On Sat, Mar 21, 2015 at 7:48 PM, Stephan Ewen <se...@apache.org> wrote: > Hi Flavio! > > I see initially two ways of doing this: > > 1) Do a series of joins. You start with your subject and join two or three > times using the "objects-from-triplets == subject" to make one hop. You can > filter the verbs from the triplets before if you are only interested in a > special relationship. > > 2) If you want to recursively explode the subgraph (something like all > reachable subjects) or do a rather long series of hops, then you should be > able to model this nicely as a delta iterations, or as a vertex-centric > graph computation. For that, you can use both "Gelly" (the graph library) > or the standalone Spargel operator (Giraph-like). > > Does that help with your questions? > > Greetings, > Stephan > > > On Thu, Mar 19, 2015 at 2:57 PM, Flavio Pompermaier <pomperma...@okkam.it> > wrote: > > > Hi to all, > > I'm back to this task again :) > > > > Summarizing again: I have some source dataset that has contains RDF > "stars" > > (SubjectURI, RdfType and a list of RDF triples belonging to this subject > -> > > the "a.k.a." star schema) > > and I have to extract some sub-graphs for some RDF types of interest. > > As described in the previous email I'd like to expand some root node (if > > its type is of interest) and explode some of its path(s). > > For example, if I'm interested in the expansion of rdf type Person (as in > > the example), I could want to create a mini-graph with all of its triples > > plus those obtained exploding the path(s) > > knows.marriedWith and knows.knows.knows. > > At the moment I do it with a punctual get from HBase but I didn't > > get whether this could be done more efficiently with other strategies in > > Flink. > > @Vasiliki: you said that I could need "something like a BFS from each > > vertex". Do you have an example that could fit my use case? Is it > possible > > to filter out those vertices I'm interested in? > > > > Thanks in advance, > > Flavio > > > > > > On Tue, Mar 3, 2015 at 8:32 PM, Vasiliki Kalavri < > > vasilikikala...@gmail.com> > > wrote: > > > > > Hi Flavio, > > > > > > if you want to use Gelly to model your data as a graph, you can load > your > > > Tuple3s as Edges. > > > This will result in "http://test/John";, "Person", "Frank", etc to be > > > vertices and "type", "name", "knows" to be edge values. > > > In the first case, you can use filterOnEdges() to get the subgraph with > > the > > > relation edges. > > > > > > Once you have the graph, you could probably use a vertex-centric > > iteration > > > to generate the trees. > > > It seems to me that you need something like a BFS from each vertex. > Keep > > in > > > mind that this can be a very costly operation in terms of memory and > > > communication for large graphs. > > > > > > Let me know if you have any questions! > > > > > > Cheers, > > > V. > > > > > > On 3 March 2015 at 09:13, Flavio Pompermaier <pomperma...@okkam.it> > > wrote: > > > > > > > I have a nice case of RDF manipulation :) > > > > Let's say I have the following RDF triples (Tuple3) in two files or > > > tables: > > > > > > > > TABLE A: > > > > http://test/John, type, Person > > > > http://test/John, name, John > > > > http://test/John, knows, http://test/Mary > > > > http://test/John, knows, http://test/Jerry > > > > http://test/Jerry, type, Person > > > > http://test/Jerry, name, Jerry > > > > http://test/Jerry, knows, http://test/Frank > > > > http://test/Mary, type, Person > > > > http://test/Mary, name, Mary > > > > > > > > TABLE B: > > > > http://test/Frank, type, Person > > > > http://test/Frank, name, Frank > > > > http://test/Frank, marriedWith, http://test/Mary > > > > > > > > What is the best way to build up Person-rooted trees with all node's > > data > > > > properties and some expanded path like 'Person.knows.marriedWith' ? > > > > Is it better to use Graph/Gelly APIs, Flink Joins, multiple punctuals > > get > > > > from a Key/value store or what? > > > > > > > > The expected 4 trees should be: > > > > > > > > tree 1 (root is John) ------------------ > > > > http://test/John, type, Person > > > > http://test/John, name, John > > > > http://test/John, knows, http://test/Mary > > > > http://test/John, knows, http://test/Jerry > > > > http://test/Jerry, type, Person > > > > http://test/Jerry, name, Jerry > > > > http://test/Jerry, knows, http://test/Frank > > > > http://test/Mary, type, Person > > > > http://test/Mary, name, Mary > > > > http://test/Frank, type, Person > > > > http://test/Frank, name, Frank > > > > http://test/Frank, marriedWith, http://test/Mary > > > > > > > > tree 2 (root is Jerry) ------------------ > > > > http://test/Jerry, type, Person > > > > http://test/Jerry, name, Jerry > > > > http://test/Jerry, knows, http://test/Frank > > > > http://test/Frank, type, Person > > > > http://test/Frank, name, Frank > > > > http://test/Frank, marriedWith, http://test/Mary > > > > http://test/Mary, type, Person > > > > http://test/Mary, name, Mary > > > > > > > > tree 3 (root is Mary) ------------------ > > > > http://test/Mary, type, Person > > > > http://test/Mary, name, Mary > > > > > > > > tree 4 (root is Frank) ------------------ > > > > http://test/Frank, type, Person > > > > http://test/Frank, name, Frank > > > > http://test/Frank, marriedWith, http://test/Mary > > > > http://test/Mary, type, Person > > > > http://test/Mary, name, Mary > > > > > > > > Thanks in advance, > > > > Flavio > > > > > > > > On Mon, Mar 2, 2015 at 5:04 PM, Stephan Ewen <se...@apache.org> > wrote: > > > > > > > > > Hey Santosh! > > > > > > > > > > RDF processing often involves either joins, or graph-query like > > > > operations > > > > > (transitive). Flink is fairly good at both types of operations. > > > > > > > > > > I would look into the graph examples and the graph API for a start: > > > > > > > > > > - Graph examples: > > > > > > > > > > > > > > > > > > > > https://github.com/apache/flink/tree/master/flink-examples/flink-java-examples/src/main/java/org/apache/flink/examples/java/graph > > > > > - Graph API: > > > > > > > > > > > > > > > > > > > > https://github.com/apache/flink/tree/master/flink-staging/flink-gelly/src/main/java/org/apache/flink/graph > > > > > > > > > > If you have a more specific question, I can give you better > pointers > > > ;-) > > > > > > > > > > Stephan > > > > > > > > > > > > > > > On Fri, Feb 27, 2015 at 4:48 PM, santosh_rajaguru < > sani...@gmail.com > > > > > > > > wrote: > > > > > > > > > > > Hello, > > > > > > > > > > > > how can flink be useful for processing the data to RDFs and build > > the > > > > > > ontology? > > > > > > > > > > > > Regards, > > > > > > Santosh > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > View this message in context: > > > > > > > > > > > > > > > > > > > > > http://apache-flink-incubator-mailing-list-archive.1008284.n3.nabble.com/Queries-regarding-RDFs-with-Flink-tp4130.html > > > > > > Sent from the Apache Flink (Incubator) Mailing List archive. > > mailing > > > > list > > > > > > archive at Nabble.com. > > > > > > > > > > > > > > > > > > > > >
