FailoverUniSessionFactory

Like the original UniSessionFactory, this class provides connected sessions to UniData.

package edu.asu.vpia.dao;
import asjava.uniobjects.[[UniSession]];
import asjava.uniobjects.[[UniSessionException]];

import java.io.[[InputStream]];
import java.util.Properties;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.[[LogFactory]];

/**
 *  Factory method to create connected [[UniSession]] objects Uses the provided
 *  .properties filename, or 'unidata.properties' if none is provided. File must
 *  be on the classpath. The properties file must contain
 *  [[ACCOUNT_PATH]]=/path/to/data and may contain definitions for [[HOST_NAME]],
 *  [[HOST_PORT]], [[CONNECTION_STRING]] [[USER_NAME]], PASSWORD and TIMEOUT to override the
 *  default settings. FAILOVER is optional and
 *  names the next .properties file to try if we are unable to connect using the
 *  initial one. 
 *
 *@author     Wendy Smoak
 *@created    2003
 */

public class [[UniSessionFactory]]
{
   private static Log log = [[LogFactory]].getLog( [[UniSessionFactory]].class );

   /[[/UniData]] defaults:
   //private static final int [[HOST_PORT]] = 31438;
   private final static String [[CONNECTION_STRING]] = "udcs";
   private final static String [[HOST_NAME]] = "your.host.name";
   private final static String [[USER_NAME]] = "user";
   private final static String PASSWORD = "pass";
   //private static final String [[ACCOUNT_PATH]] = "/path/to/data";

   private final static String [[PROPS_FILENAME]] = "unidata.properties";

   /[[/UniVerse]] defaults:
   //private static final String [[CONNECTION_STRING]] = "uvcs";

   /**
    *  Private constructor. This class contains only static methods
    */
   private [[UniSessionFactory]]() { }


   /**
    *  Opens a session using the default .properties filename (unidata.properties)
    *
    *@return                          Description of the Return Value
    *@exception  [[UniSessionException]]  Description of the Exception
    *@exception  DAOException         Description of the Exception
    */
   public static [[UniSession]] openSession() throws [[UniSessionException]], DAOException
   {
      log.debug( "openSession: using default unidata.properties filename" );
      return openSession( [[PROPS_FILENAME]] );
   }


   /**
    *  Opens a session using the provided .properties filename
    *
    *@param  props[[FileName]]            Description of the Parameter
    *@return                          Description of the Return Value
    *@exception  [[UniSessionException]]  Description of the Exception
    *@exception  DAOException         Description of the Exception
    */
   public static [[UniSession]] openSession( String props[[FileName]] )
       throws [[UniSessionException]], DAOException
   {
      [[UniSession]] uSession = new [[UniSession]]();
      //log.debug( "openSession: uSession=" + uSession );

      //you cannot change the port on [[UniData]], so no need [for me]
      //to pull this from the .properties file.
      //uSession.set[[HostPort]]( [[HOST_PORT]] );

      Properties props = new Properties();

      try {
         [[ClassLoader]] cl = [[UniSessionFactory]].class.get[[ClassLoader]]();
         [[InputStream]] input = cl.get[[ResourceAsStream]]( props[[FileName]] );

         if ( input == null ) {
            log.fatal( "openSession: Unable to load " + props[[FileName]] );
            throw new DAOException( "Properties file " + props[[FileName]] + " missing" );
         }
         props.load( input );

         //set the [[UniSession]] properties, using the defaults if the
         //values are not present in the [[PROPS_FILENAME]] file
         /[[/ACCOUNT_PATH]] *must* be in the properties file, no default provided
         //uSession.set[[AccountPath]]( props.getProperty( "[[ACCOUNT_PATH]]", [[ACCOUNT_PATH]] ) );
         uSession.set[[AccountPath]]( props.getProperty( "[[ACCOUNT_PATH]]" ) );
         uSession.set[[HostName]]( props.getProperty( "[[HOST_NAME]]", [[HOST_NAME]] ) );
         uSession.set[[UserName]]( props.getProperty( "[[USER_NAME]]", [[USER_NAME]] ) );
         uSession.setPassword( props.getProperty( "PASSWORD", PASSWORD ) );
         uSession.set[[ConnectionString]]( props.getProperty( "[[CONNECTION_STRING]]", [[CONNECTION_STRING]] ) );

         int defaultTimeout = uSession.getTimeout();
         int timeout = Integer.parseInt( props.getProperty( "TIMEOUT", String.valueOf( defaultTimeout ) ) );
         uSession.setTimeout( timeout );

         log.debug( "openSession: [[ACCOUNT_PATH]]=" + uSession.get[[AccountPath]]()
             + " [[HOST_NAME]]=" + uSession.get[[HostName]]()
             + " [[USER_NAME]]=" + uSession.get[[UserName]]() );

      } catch ( java.io.IOException ex ) {
         log.error( ex );
         throw new DAOException( ex );
      }

      try {
         uSession.connect();
      } catch ( [[UniSessionException]] ex ) {
         String failover = props.getProperty( "FAILOVER" );
         if ( failover != null && !failover.equals( "" ) ) {
            log.debug( "openSession: failing over to " + failover );
            return [[UniSessionFactory]].openSession( failover );
         } else {
            throw new DAOException( ex );
         }
      }
      log.debug( "connected to " + uSession.get[[AccountPath]]() );

      return uSession;
   }
}