/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package tx;


import com.hp.hpl.jena.query.Dataset ;
import com.hp.hpl.jena.query.DatasetFactory ;
import com.hp.hpl.jena.query.QueryExecution ;
import com.hp.hpl.jena.query.QueryExecutionFactory ;
import com.hp.hpl.jena.query.ResultSet ;
import com.hp.hpl.jena.query.ResultSetFormatter ;
import com.hp.hpl.jena.tdb.DatasetGraphTxn ;
import com.hp.hpl.jena.tdb.ReadWrite ;
import com.hp.hpl.jena.tdb.StoreConnection ;
import com.hp.hpl.jena.tdb.transaction.Transaction ;
import com.hp.hpl.jena.update.UpdateExecutionFactory ;
import com.hp.hpl.jena.update.UpdateFactory ;
import com.hp.hpl.jena.update.UpdateProcessor ;
import com.hp.hpl.jena.update.UpdateRequest ;

public class ExTxTDB
{
    // Internal state of a DSG
    enum DSG_STATE { DSG_READ, DSG_WRITE, DGS_BLOCKED } ;
    
    interface DatasetTx extends Dataset
    {
        public Transaction getTransaction() ; //{ return transaction ; }
        public void commit() ; // { transaction.commit() ; }
        public void abort() ; //{ transaction.abort() ; }
    }
    
    public static void example1()
    {
        StoreConnection sConn = StoreConnection.make("DB") ;
        
        sparqlQuery(sConn) ;
        sparqlUpdate(sConn) ;
    }

    private static void sparqlQuery(StoreConnection sConn)
    {
        DatasetGraphTxn dsg = sConn.begin(ReadWrite.READ) ;
        try {
            Dataset ds = DatasetFactory.create(dsg) ;
            QueryExecution qExec = QueryExecutionFactory.create("SELECT * { ?s ?p ?o} LIMIT 10", ds) ;
            ResultSet rs = qExec.execSelect() ;
            try {
                ResultSetFormatter.out(rs) ;
            } finally { qExec.close() ; }

            // Another query - same view of the data.
            qExec = QueryExecutionFactory.create("SELECT * { ?s ?p ?o} OFFSET 10 LIMIT 10", ds) ;
            rs = qExec.execSelect() ;
            try {
                ResultSetFormatter.out(rs) ;
            } finally { qExec.close() ; }

        } finally { dsg.close() ; }
    }

    private static void sparqlUpdate(StoreConnection sConn)
    {
        DatasetGraphTxn dsg = sConn.begin(ReadWrite.WRITE) ;
        try {
            // Query
            QueryExecution qExec = QueryExecutionFactory.create("SELECT * { ?s ?p ?o} LIMIT 10", /*dsg*/(Dataset)null) ;
            ResultSet rs = qExec.execSelect() ;
            try {
                ResultSetFormatter.out(rs) ;
            } finally { qExec.close() ; }

            // Update
            UpdateRequest request = UpdateFactory.create("PREFIX : <http://example/> INSERT DATA { :s :p :o}") ;
            UpdateProcessor proc = UpdateExecutionFactory.create(request, dsg) ;
            proc.execute() ;
            dsg.commit() ;
        } finally { dsg.close() ; } // WARNING if no commit or abort.
    }
}