Some code to test 4store. Store r/qtl cross object as N3 formatted file. We then use 2 shell commands (printed by R): (1) converts n3 to rdf, (2) upload to the 4store database using curl. After this we can use: 'rdmd tripleStore.d' to query the triple store.

.gitignore

*~
*.rdf
*.n3

crossToTripleStore.R

# CrossObject to N3 format
crossToNTriplet <- function(cross, dataset = "default", file = ""){
  cat("@prefix : <http://www.rqtl.org/ns/#> .\n", file=file)
  cat("@prefix individual: <http://www.rqtl.org/ns/individual#> .\n", file=file, append=TRUE)
  cat("@prefix marker: <http://www.rqtl.org/ns/marker#> .\n",     file=file, append=TRUE)
  cat("@prefix location: <http://www.rqtl.org/ns/location#> .\n",   file=file, append=TRUE)
  cat("@prefix phenotype: <http://www.rqtl.org/ns/phenotype#> .\n",  file=file, append=TRUE)
  map <- pull.map(cross)
  for(chr in names(map)){
    for(mar in names(map[[chr]])){
      mname <- sub("/","_",mar)
      cat(paste0("marker:", mname," location:chr ", chr," .\n"), file=file, append=TRUE)
      cat(paste0("marker:", mname," location:cm ", map[[chr]][mar]," .\n"), file=file, append=TRUE)
      geno <- pull.geno(cross)[,mar]
      for(ind in 1:length(geno)){
        cat(paste0("individual:", ind," marker:", mname," \"", geno[ind],"\" .\n"), file=file, append=TRUE)
      }
    }
  }
  for(phe in names(pull.pheno(multitrait))){
    pheno <- pull.pheno(cross)[,phe]
    for(ind in 1:length(pheno)){
      cat(paste0("individual:", ind," phenotype:", phe," \"", pheno[ind],"\" .\n"), file=file, append=TRUE)
    }
  }
}

# CrossObject to N3->RDF and upload to 4 store tripleStore
crossTotripleStore <- function(cross, file="default", toRDF=TRUE, to4Store=TRUE, host = "localhost", port=9000){
  rdfname <- paste0(file, ".rdf")
  crossToNTriplet(cross, dataset=file, file=paste0(file,".n3"))
  if(file != ""){    
    cat("For RDF and 4Store upload execute:\n")
    cat(paste0("cd ", getwd(), "\n"))
    if(toRDF) cat(paste0("rdfcat -in N3 -out RDF/XML -n ", file, ".n3 > ", rdfname,"\n"))
    if(to4Store) cat(paste0("curl -T '", rdfname, "' http://",host,":",port,"/data/", rdfname,"\n"))
  }
}

library(qtl)
data(multitrait)
crossTotripleStore(multitrait,"multitrait")

tripleStore.d

import std.stdio, std.math, std.conv, std.socket, std.string;

/** Triple store class object */
class TripleStore{
  public:
    /** Constructor for the TripleStore object */
    this(string h = "localhost", ushort p = 9000){ 
      host = h; port = p;
    }

    /** Query the triple store with query string query, supported formats: text, json, sparql */
    string query(string query, string format="text", bool noHeader = true, uint buffersize = 1024){
      connect();
      scope(exit) disconnect();
      write("GET "~url~"?query="~query~"&output="~format~" "~protocol~"\r\nHost: "~host~"\r\n\r\n");
      return readOutput(noHeader, buffersize);
    }

    /** Connect to a triple store */
    bool connect(){
      try{
        if(handle is null) handle = new TcpSocket();
        handle.connect(new InternetAddress(host, cast(int)port));
        handle.blocking(true);
      }catch(SocketException ex){
        writefln("Failed to connect to server (%s:%d)", host, port);
        handle = null;
        return false;
      }
      return true;
    }

    /** Disconnect from a triple store */
    void disconnect(){
      if(isAlive()){ handle.close; delete handle; }
    }

  private:
    bool write(string msg){ // Write a message to server
      if(!isAlive()) return false;
      auto ret = handle.send(msg);
      return (ret < 0);
    }

    bool isAlive(){ // Is our handle still alive
      if(handle !is null) return handle.isAlive;
      return false;
    }

    string readOutput(bool noHeader = true, uint buffersize = 1024){ // Read the output from the server  
      if(!isAlive()) return null;
      string response;
      char[] buf = new char[buffersize];
      int ret;
      while((ret = handle.receive(buf)) > 0){
        response ~= to!string(buf[0 .. ret].dup);
      }
      if(noHeader) response = response[(response.indexOf("\r\n\r\n")+4) .. $];
      return response;
    }

    string host     = "localhost"; // Host to connect to
    string url      = "/sparql/";  // Url prefix on host for sparql queries
    string protocol = "HTTP/1.0";  // HTTP version we want to use
    ushort port     = 9000;        // Port to connect on
    Socket handle   = null;        // Socket to server (called handle)
}

void main(string[] args){
  TripleStore store = new TripleStore("localhost", 9000);
  string query  = "SELECT * WHERE {?s ?p ?o} LIMIT 3";  // Default query
  string format = "text";                               // Default format
  if(args.length > 1) query  = args[1];
  if(args.length > 2) format = args[2];
  writefln("%s", store.query(query, format));
}