JDBC Connection Failover

FAN

With JDBC thin 11.2 and simplefan.jar (oracle.simplefan package) I was able to perform tests only with ONS client running locally. The program and the test environment has been described at Martin Bach's blog. Ons can be installed with the full version of Oracle 11.2 Windows client (standard install). It requires changes in the ons.config: usesharedinstall=false and nodes=node1:6200,node2:6200,node3:6200. By default usessharedinstall is set to true, which makes the lock file appending the hostname to it. Consequently it renders the example being not able to found it by the standard name. I didn't investigate how to fix it at the code level.

Speaking on JDBC thin it is suprising how little of information I could find in the Internet. The only valuable information from Oracle comes with Oracle Database RAC FAN Events Java 11g Release 2 (11.2) E13993-01 and there is not working example in Oracle Database JDBC Developer's Guide 11g Release 2 (11.2). Not working not only because it is not quite complete, but because it refers to not existing methods: Actually didn't find methods like getServiceMemberStatus, getServiceCompositeEvent and some others within simplefan.jar and the above API documentation. Searching with Google for these methods returns the above (not working) example only. In a similar way, existing function don't handle coming events properly. The "SHUTDOWN" event is an example here.

The code below is original Oracle's example mixed with Martin Bach's code:

package org.kedra.fan1;
import java.util.Properties;
import oracle.simplefan.FanEventListener;
import oracle.simplefan.FanManager;
import oracle.simplefan.FanSubscription;
import oracle.simplefan.LoadAdvisoryEvent;
import oracle.simplefan.NodeDownEvent;
import oracle.simplefan.ServiceDownEvent;
import oracle.simplefan.ServiceDownEvent.ServiceMemberEvent;

public class Test1 {
 Test1() {
  FanManager fm = FanManager.getInstance();

  //Properties fmProps = new Properties();
  //fmProps.setProperty("onsNodes",
  //  "plabb241:6200,plabb230:6200,plabb229:6200");
  // fmProps.setProperty(key, value)
  // fm.configure(fmProps);

  System.setProperty("oracle.ons.oraclehome",
    "c:\\Oracle2\\product\\11.2.0\\client_1");
  System.out.println(System.getProperty("oracle.ons.oraclehome"));

  Properties props = new Properties();
  props.put("serviceName", "AMQS1");

  FanSubscription sub = fm.subscribe(props);
  System.out.println("I'm subscribed!");

  sub.addListener(new FanEventListener() {

   public void handleEvent(ServiceDownEvent event) {
    System.out.println("ServiceDownEvent!");

    try {
     System.out.println(event.getTimestamp());
     System.out.println("getServiceName: "
       + event.getServiceName());
     System.out.println("getDatabaseUniqueName: "
       + event.getDatabaseUniqueName());
     System.out.println("getReason: " + event.getReason());
     System.out.println("getKind: " + event.getKind());

     ServiceMemberEvent me = event.getServiceMemberEvent();
     if (me != null) {
      System.out.println("getServiceMemberEvent");
      System.out.println("\t getInstanceName: "
        + me.getInstanceName());
      System.out.println("\t getNodeName: "
        + me.getNodeName());
      // System.out.println(me.getServiceMemberStatus());
     }
     // ServiceCompositeEvent ce = se.getServiceCompositeEvent();
     // if (ce != null) {
     // System.out.println(ce.getServiceCompositeStatus());
     // }
    } catch (Throwable t) {
     // handle all exceptions and errors
     System.err.println("handleEvent - ServiceDownEvent");
     t.printStackTrace(System.err);
    }
   }

   public void handleEvent(NodeDownEvent event) {
    System.out.println("Node Down Event!");

    try {
     System.out.println(event.getTimestamp());
     System.out.println("getNodeName: " + event.getNodeName());
     // ServiceCompositeEvent ce = se.getServiceCompositeEvent();
     // if (ce != null) {
     // System.out.println(ce.getServiceCompositeStatus());
     // }
    } catch (Throwable t) {
     System.err.println("handleEvent - ServiceDownEvent");
     t.printStackTrace(System.err);
    }
   }

   public void handleEvent(LoadAdvisoryEvent arg0) {
    System.out.println("Load Advisory event");

    System.out.println("originating database: "
      + arg0.getDatabaseUniqueName());
    System.out.println("originating instance: "
      + arg0.getInstanceName());
    System.out.println("Service Quality     : "
      + arg0.getServiceQuality());
    System.out.println("Percent             : " + arg0.getPercent());
    System.out.println("Service Name        : "
      + arg0.getServiceName());
    System.out.println("Service Quality     : "
      + arg0.getServiceQuality());
    System.out.println("Observed at         : "
      + arg0.getTimestamp() + "\n\n");
   }
  });
 }

 public static void main(String[] args) {
  Test1 tc = new Test1();

  int i = 0;
  while (i < 100000) {
   try {
    Thread.sleep(100);
    i++;
   } catch (Exception e) {
    System.out.println(e);
   }
  }

  System.out.println("execution ended");
 }
}

I would like to see a support for a remote ONS. There is a method configure() in the FanManager class which takes a list of ONS servers but requires mandatory oracle wallet and password as well. This is not something I expect - for I don't want the communication with ONS server over SSL.

Oracle admits it is "the initial release" so the functionality of this library is fairly limited.

Fast Connection Failover

Fast Connection Failover (FCF) and for JDBC thin it us usable with Universal Connection Pool (UCP). There is an option to use JDBC Implicit Connection Cache (ICC) but Oracle considers the feature to be replaced by UCP.

1. Automatic Workload Management with Oracle Real Application Clusters 11g Release 2 - FAN, FCF
2. Maximum Availability Architecture, Oracle Best Practices For High Availability: Client Failover Best Practices for Highly Available Oracle  Databases: Oracle Database 11g Release 2 - Standby database oriented.
3. Fast Connection Failover Example JDBC Thin - this is about 10g High Availability and JDBC. Requires ons.jar or ONS working on the client side. Great resource for hands-on experience.
4. How to Verify Universal Connection Pool (UCP) / Fast Connection Failover (FCF) Setup (Metalink Doc ID 1064652.1)
5. JDBC and Universal Connection Pool
6. UCP Demos Page (Oracle)
7. TAF vs FAN, FCF vs ONS
8.  Metalink Resources:
• How ONS and FCF work with JDBC (Doc ID 752595.1)
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