Connecting to a Service: An Example

The following example illustrates how to create a service and then gives several examples of connecting to that service using different client methods.

In this example the service is enabled for run-time load balancing, as follows:

• Service Name: HR.example.com

  • Running on database named CRM

  • The system consists of 4 nodes

• Specifying SERVICE_TIME as the value for the -rlbgoal parameter

• SCAN address of the listener is rws3010104-scan.example.com

• Listener port is 1585

The service has a cardinality of two, but if needed, can be offered by any of the CRM database instances. The service configuration is as follows:

• Preferred Instances: CRM1, CRM2

• Available Instances: CRM3, CRM4

• Specifying SHORT as the value for the -clbgoal parameter

The application using this service takes advantage of Application Continuity, so you must set -failovertype and -commit_outcome. Use the default retention parameters, but set a 10 second delay between connection attempts, and up to 40 retries before failing to get a connection.

Create the HR service using SRVCTL, as follows:

$ srvctl add service –db CRM –service HR.example.com –preferred CRM1,CRM2
    –available CRM3,CRM4 –clbgoal SHORT –failovertype TRANSACTION
    –commit_outcome TRUE –failoverdelay 10 –failoverretry 40

Start the HR.example.com service, as follows:

$ srvctl start service –db CRM –service HR.example.com

The service is now be available on up to two instances, and CRM1 and CRM2 are the preferred instances.

The application that connects to the HR service, in this example, is a JDBC application using the JDBC Universal Connection Pool with the JDBC thin driver.

In this example, a URL is constructed specifying the thin-style service name format for the database specifier. Fast Connection Failover is enabled, and remote Oracle Notification Service is configured, where the Oracle Notification Service daemon on the cluster listens on port 6200.

//import packages and register the driver
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import oracle.ucp.jdbc.PoolDataSourceFactory;
import oracle.ucp.jdbc.PoolDataSource;

PoolDataSource  pds = PoolDataSourceFactory.getPoolDataSource();

//set the connection properties on the data source.
pds.setConnectionPoolName("FCFPool");
pds.setFastConnectionFailoverEnabled(true);
pds.setONSConfiguration("nodes=rws3010104-scan.example.com:6200");
pds.setConnectionFactoryClassName("oracle.jdbc.pool.OracleDataSource");
pds.setURL("jdbc:oracle:thin:@//rws3010104-scan.example.com:1585/HR.example.com");
pds.setUser("HR");
pds.setPassword("hr"); 
    
 
//Override any pool properties.
pds.setInitialPoolSize(5);
 
//Get a database connection from the datasource.
 
Connection conn = pds.getConnection();
 
// do some work
 
//return connection to pool
conn.close();
conn=null