Raw notes from RDF Query BOF, SWWS, 2001-08-01 Libby Miller Wrote up sample queries on the whiteboard for 4 of the 8 query languages in the room (see http://swordfish.rdfweb.org/photos/2001/08/01/) Eric Prud'hommeaux led the classification of the query languages into: subgraph matching "reachable" (keep following arcs out of a node - David Allsopp's implementation does this) + subgraph constraints on reachability + a special case of this is transitive closure (e.g. follow subclass arcs only) EP: Reachable is like a transitive query with any predicate more specialised is transitive query with any predicate, like transitive closure with subclass and subproperty. AM: what about rules? EP: none of these have assertion capability. where do assertions go? - the originial dataset? (changing the set) - a working set? audience member: might want to select from a set of rules as well as from a set of RDF documents [then we went around the room, each of us saying our names and why we were interested in RDF query.] Libby Miller: Squish, Inkling: simple, for testing, for scripters Jeen: Sesame, one of two implementations of RQL. An RDF schema language quite complex but powerful - native support for RDF schema semantics not querying triples but the graph. path expression syntax Ontoknowledge project partner - a requirement to be able to query the ontology. EP: 0 --> O --> 0 vs 0 --> 0 and 0 --> 0 ? Jeen: yes Michel Klein: want a query language making the semantics useful for scripting, an instant QL EP: scenarios in mind? MK: PHP Fernando Arguello: An undergraduate at Stanford. Wanted to learn about RDF query and specifically efficient RDF query language implementations Don Johnson: Helps people map out requirements for requirement engineering His organisation used SQL for years, but the database was too controlled and prevented people from expressing their ideas fully. Now they are using a semantic web solution. This is interesting, but it takes a lot of time to go through the data. Aim is therefore to speed requirements analysis They have a simple query language which is inefficient but better than nothing didn't catch his name: - a grad student at Stanford interested in efficient query H Holger Rath: works for Empolis coeditor of TMQL collecting requirements for TMQL at the moment, hopefully approval soon. waiting for the data model group interested in discussing requirements EP: figuring out the relationship between RDF and TM is useful Chutiporn Anutariya: Asian Institute of technology - PhD student working on a framework for modeling and manipulating RDF data. Has a query language with an XML syntax. David Jones: Boeing part of the 'user community' for RDF query. has lots of data not in RDF, which needs to stay in that form. wants an RDF query language which will do query transformations getting instance data from relational databases using schemas also would like to be able to query any XML document use RDF to get answers over different RDF data sources. Sarah Comai works on databases and XML query languages. Pierre-Antoine Champin workig on case based reasoning where the case is an RDF graph. cases where subgraph matches the pattern interested in matching similar graphs rather than exactly matching graphs. an assistant system. didn't catch his name: student at Maryland working on the DAML project has a query language - rules based mostly interested in storage issues Matthias Palmer Royal institute of technology Stockholm (KTH) human-computer interactions mind maps, concept maps -> RDF transitivity, inheritance of metadata, graphical interface Todd Siegel - likes good questions, fond of language - e.g. aggregating people by similarities in their tastes - 'tasty matrix' David Allsopp works for QinetiQ, which was the Defence Evaluation and Research agency in the UK legacy systems -> RDF has a QL, in memory triple store wants a realistic way of storing the data if untrustworthy relates to query because need to be able to use this to pick out the set to query. stored data reified but doesn't want to use quads to query it message-based you can get complete docs for context efficiency Eric Prud'hommeaux: W3C writing RDF, semantic web tools 2 years Algae is QL 'hammer I run round with and see everything as a nail' :) e.g. Annotea Algae is an API and a data structure and a s_expression query language can do assertions - general triple store - in-memory triple store - general SQL access [end of intros] DJ: what is the status of RDF query? EP: here's the W3C process: - membership say we want stuff - a F2F meetign is held for interested parties - call for participation goes out to the members - members vote yes or no -> activity - strawman proposal, constraints, requirements WG - evaluate existing ones, crate new one maybe results go to membership and then director none of these things had been done get for RDF query often want to go through the process if divergence will hurt the industry DJ: what good is RDF is you can't query it? query is very useful DA: API stuff, but yeah EP: sources to query? - http resources - local files - triples stores, could be relational databases - general RDB - not a triple store - arbitrary xml - API, messaging DJ: trust needs to be embedded deeply there's a difference between SQL which is tightly controlled EP: yeah, what I call a 'homogenous trust environment' - same level of trust trust is part of the selection criteria. It comes from the sources - is defined in the sources DA: tagging internal data yourself EP: Algae can get quads out - you can say, I only want to get things from one source DA: 2 different levels - query external databases and query own databases EP: reification and quads quads or reified - same 4th is often called the attribution or context dereferencing the statement ID can get the attribution in Algae - especially useful for Annotations - http credence HHR: [gives brief introduction to topic maps]: topic as central point address it directly via url of subject if not addressible have to invent an addressible thing to represent it Xlink - potentially 2+ links to the same subject - updates? - contents? - requerying ? http://groups.yahoo.com/group/tmql-wg EP: I'll find/set up a list for RDF query Participants Jeen Broekstra Administrator jeen.broekstra@aidministrator.nl Michel Klein Vrye Universiteit mcaklein@cs.vu.nl J. Fernando Arguello Stanford University elticochico@yahoo.com Don johnson TASC drj826@acm.org H Holder Rath Empolis holger.rath@empolis.com David H Jones Boeing david.h.jones@boeing.com Sara Comai Politecnio di Milano sara.comai@polimi.it Marc Edgar GE edgarm@crd.ge.com Matthias palmer KTH (Stockholm) matthias@nada.kth.se Pierre-Antoine Champin University of Lyon 1 champin@lisi.univ-lyon1.fr Chutiporn Anutariya Asian Institute if Technology ca@cs.ait.ac.th Todd Siegel tastymatrix tsiegel@hotmail.com David Allsopp QinetiQ d.allsopp@signal.QinetiQ.com Eric Prud'hommeaux W3C eric@w3.org Libby Miller ILRT University of Bristol libby.miller@bristol.ac.uk