Title: SDB Joseki Integration

[Joseki](http://www.joseki.org "http://www.joseki.org") is a server
that implements the SPARQL protocol for HTTP. It can be used to
give a SPARQL interface to an SDB installation.

The Joseki server needs the SDB jar files on its classpath. The
Joseki configuration file needs to contain two triples to integrate
SDB:

    ## Initialize SDB.
    [] ja:loadClass "com.hp.hpl.jena.sdb.SDB" .

    ## Declare that sdb:DatasetStore is an implementation of ja:RDFDataset .
    sdb:DatasetStore rdfs:subClassOf ja:RDFDataset .

then a Joseki service can use an SBD-implemented dataset:

    <#books> rdf:type sdb:DatasetStore ;
       sdb:store <#store> .

     <#store> rdf:type sdb:Store  ;
       rdfs:label "SDB" ;
       sdb:layout         "layout2" ;
       sdb:connection
        [  rdf:type sdb:SDBConnection ;
           sdb:sdbType        "postgresql" ;
           sdb:sdbHost        "localhost" ;
           sdb:sdbName        "SDB" ;
        ]
        .

To enable pooling of connections to the SDB store, use the
joseki:poolSize property. This causes Joseki to create a pool of
SDB datasets, each with it's own JDBC connection. This requires
Joseki 3.2.

    <#sdb> rdf:type sdb:DatasetStore ;
        joseki:poolSize     5 ;         # Number of concurrent connections allowed to this dataset.
        sdb:store <#store> .

SDB 1.0:

    ## Dataset in SDB.
    <#books> rdf:type sdb:DatasetStore , ja:RDFDataset ;
        rdfs:label       "Books" ;
        sdb:layout       "layout2" ;
        sdb:connection
        [  rdf:type sdb:SDBConnection ;
           sdb:sdbType        "postgresql" ;
           sdb:sdbHost        "localhost" ;
           sdb:sdbName        "SDB" ;
        ]
        .

The database installation does not need to accept public requests,
it needs only to be accessible to the Joseki server itself.

There is an example configuration file for a Joseki server using
SDB in the Joseki distribution.