package example;

import uk.org.ogsadai.client.toolkit.activity.ActivityRequest;
import uk.org.ogsadai.client.toolkit.activity.sql.SQLQuery;
import uk.org.ogsadai.client.toolkit.ogsi.OGSIServiceFetcher;
import uk.org.ogsadai.client.toolkit.service.DataService;
import uk.org.ogsadai.client.toolkit.service.ServiceFetcher;

/**
 * This example shows how to use multiple client DataServices to perform 
 * concurrent requests.
 */
public class ConcurrentQueries
{
    public static void main(String[] args) throws Exception
    {
        // the handle for the GDSF
        
        String handle = "http://localhost:8080/ogsa/services/ogsadai/" +
                "GridDataServiceFactory";

        // create the correct servce fetcher
        
        ServiceFetcher fetcher = OGSIServiceFetcher.getInstance();

        // create multiple client data services for performing each request 
        
        DataService service1 = fetcher.getDataService(handle, null);
        DataService service2 = fetcher.getDataService(handle, null);
        
        // create threads for each concurrent request
        
        Thread thread1 = createProcessingThread(
            service1, 
            "select * from littleblackbook where id=43");
        Thread thread2 = createProcessingThread(
            service1, 
            "select * from littleblackbook where id=76");
        
        // start request threads
        
        thread1.start();
        thread2.start();

        // wait for requests to finish
        
        thread1.join();
        thread2.join();
       
        // close services
        
        service1.close();
        service2.close();
    }
    
    /**
     * Create and return a <code>Thread</code> to perform an SQL query using
     * the specified data service.
     * 
     * @param service
     *            the data service to perform the query
     * @param sql
     *            the SQL query to perform using the data service
     * @return a new <code>Thread</code> object, unstarted
     */
    public static Thread createProcessingThread(
        final DataService service,
        final String sql)
    {
        Runnable r = new Runnable()
        {
            public void run()
            {
                ActivityRequest request = new ActivityRequest();
                SQLQuery query = new SQLQuery(sql);

                try
                {
                    service.perform(query);
                    System.out.println("Results from query: ");
                    System.out.println(query.getOutput().getData());
                }
                catch (Exception e)
                {
                    System.out.println("Error performing query: " + sql);
                    e.printStackTrace();
                }
            }
        };
        
        return new Thread(r);
    }
}