Using F# for the semantic web implementing in memory triple stores

Question

What is an effective means of implementing an in memory semantic web triple store using the basic .NET collection classes using F#?

Are there any F# examples or projects already doing this?

Answer 1

I know this doesn't directly answer your question, but you could use 4store which is a stable, proven triplestore, and write a client for it in .Net, instead of developing your own triplestore.

Related questions

• http://stackoverflow.com/questions/304920/which-triplestore-for-rapid-semantic-web-development
• http://stackoverflow.com/questions/870417/rdf-owl-sparql-triple-stores-reasoners-and-other-semantic-web-apis-for-c

Answer 2

Intellidimension offers a .NET based in-memory triple store as part of their Semantics SDK. They often provide free licenses for research/education if you contact them.

I use their technology every single day from C# and PowerShell though and I really enjoy it.

//disclaimer: really the first time I have used F# so this may not be any good...
//but it does work

open Intellidimension.Rdf
open System.IO

let rdfXml = File.ReadAllText(@"C:\ontology.owl")
let gds = new GraphDataSource()
gds.Read(rdfXml) |> ignore
let tbl = gds.Query("select ?s ?p ?o where {?s ?p ?o} limit 10")

System.Console.Write(tbl.RowCount)
System.Console.ReadLine() |> ignore

Answer 3

There is also SemWeb which is a C# library which provides it's own SQL based Triple Store - http://razor.occams.info/code/semweb/

I'm working on a new C# library for RDF called dotNetRDF and have just released the latest Alpha http://www.dotnetrdf.org.

Here's an equivalent program to the one spoon16 showed:

open System
open VDS.RDF
open VDS.RDF.Parsing
open VDS.RDF.Query

//Get a Graph and fill it from a file
let g = new Graph()
let parser = new TurtleParser()
parser.Load(g, "test.ttl")

//Place into a Triple Store and query
let store = new TripleStore()
store.Load(g)
let results = store.ExecuteQuery("SELECT ?s ?p ?o WHERE {?s ?p ?o} LIMIT 10") :?> SparqlResultSet

//Output the results
Console.WriteLine(results.Count.ToString() ^ " Results")
for result in results.Results do
  Console.WriteLine(result.ToString())
done

//Wait for user to hit enter so they can see the results
Console.ReadLine() |> ignore

My library currently supports my own SQL databases, AllegroGraph, 4store, Joseki, Sesame, Talis and Virtuoso as backing stores

Answer 4

Check out LinqToRdf which, in addition to simple VS.NET hosted modeling tools, provides a full LINQ query provider and round-tripping data when dealing with in-memory databases:

var ctx = new MusicDataContext(@"http://localhost/linqtordf/SparqlQuery.aspx");
var q = (from t in ctx.Tracks
     where t.Year == "2006" &&
           t.GenreName == "History 5 | Fall 2006 | UC Berkeley"
     orderby t.FileLocation
     select new {t.Title, t.FileLocation}).Skip(10).Take(5);

foreach (var track in q)
{
   Console.WriteLine(track.Title + ": " + track.FileLocation);
}