Thanks, Peter. Good info. I think we ended up with a hybrid approach: we modeled a set of "Type" nodes (related to a master "Types" node), each of which includes the type metadata (property/type data) for a specific "type". "Instance" nodes then maintain a two-way relationship with their associated "Type" node so that any node can quickly obtain its Type node and so we can easily traverse all instances of a specific type...and we may end up extending this such that the properties themselves are each a node of their own, in some cases, where we need to be able to relate/search/traverse at a very detailed level. I suppose that depends on the performance implications of having lots more nodes and relationships.
In any case, it definitely seems "do-able" with Neo. -----Original Message----- From: user-boun...@lists.neo4j.org [mailto:user-boun...@lists.neo4j.org] On Behalf Of Peter Neubauer Sent: Tuesday, December 08, 2009 3:25 PM To: Neo user discussions Subject: Re: [Neo] Type metadata in properties/nodes Hi Rick, there are a number of interesting approaches to this, involving both ways to retain the metadata: 1. RDF and OWL - basically, every node will maintain a relationship to its type node (your shadow node), something like x?--RDF:TYPE-->type_node which contains info on what the type is, what properties etc. 2. Neo4j Meta package (http://components.neo4j.org/neo-meta/) - this is the concept of describing the type of things in code (Java in this case) and thus in code enforce the restrictions and type conversions on properties through the code. This does not capture any meta info in the graph but is easy to do. 3. Annotate the nodes with type info - in this approach, there is a "type" or "classname" property on any node that is used to derive the type to deserialize/serialize the object into, the rest of the meta info is contained in the upper code layers. Andreas Ronges JRuby bindings are using this approach. 4. Encode everything into a String property - this approach means shuffling everything into a string property, basically treating properties as BLOBs. Works in some cases, but certainly locks down your data in these properties. What is best depends on your domain, and there might be more approaches out there. I sense that you are asking even for an extensible type system especially on properties. That is not in scope of the core graph engine, but I am not sure if in theory it would be possible to extend the property type system, we would need to discuss that separately. Cheers, /peter neubauer COO and Sales, Neo Technology GTalk: neubauer.peter Skype peter.neubauer Phone +46 704 106975 LinkedIn http://www.linkedin.com/in/neubauer Twitter http://twitter.com/peterneubauer http://www.neo4j.org - Relationships count. http://gremlin.tinkerpop.com - PageRank in 2 lines of code. On Tue, Dec 8, 2009 at 8:43 PM, Rick Bullotta <rick.bullo...@burningskysoftware.com> wrote: > I can see how relationships could be used to map "is a duck." typing, but > I'm struggling with how to infer type from properties. In particular, while > anything could be stuffed into a String, it loses important semantics when > you do so. I'm not referring to *storage* as a String, which makes plenty > of sense - it's that the type identity of the source property is lost if you > do so. I could maintain a "shadow node" of the type metadata that could be > related to each instance with a property name/property type array, but that > seems like something that would be useful within the node model itself. > > > > Types like DateTime, hyperlinks, and so on, while quite easily storable in > Neo4J, lose useful semantics on the way in. I'd welcome your thoughts on > how others have managed this type of scenario and other techniques for "meta > tagging" nodes and properties with type or other semantic info. > > > > Thanks, > > > > Rick > > _______________________________________________ > Neo mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > _______________________________________________ Neo mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user _______________________________________________ Neo mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
