Database Connection Failover Question

[emmitt1219]

The database connection failover scheme is sticky round robin. I have a situation where our primary db2 database goes down for scheduled maintenance. When that happens, our data source swiches over to our secondary db2 db. Everything works fine there. Now, my question is. When our primary db comes back up, is there a way for me to force the data source point back to the primary db?

Thanks,

chris

[vickyk]

"emmitt1219" wrote:
Now, my question is. When our primary db comes back up, is there a way for me to force the data source point back to the primary db?

You got to write the custom URLSelector which is possible only with jboss5 , here is the sample -ds.xml file which contains it
http://anonsvn.jboss.org/repos/jbossas/trunk/testsuite/src/resources/jca/ha/test-ha-xa-ds.xml

Have a look at this
http://anonsvn.jboss.org/repos/jbossas/trunk/connector/src/main/org/jboss/resource/adapter/jdbc/URLSelectorStrategy.java

You got to implement the algorithm which you want in custom implementation of URLSelectorStrategy class .

Have a look at the default implementation here

public static class XADataSelector implements URLSelectorStrategy
 {
 private final List xaDataList;
 private int xaDataIndex;
 private XAData xaData;

 public XADataSelector(List xaDataList)
 {
 if(xaDataList == null || xaDataList.size() == 0)
 {
 throw new IllegalStateException("Expected non-empty list of XADataSource/URL pairs but got: " + xaDataList);
 }

 this.xaDataList = xaDataList;
 }

 public synchronized XAData getXAData()
 {
 if(xaData == null)
 {
 if(xaDataIndex == xaDataList.size())
 {
 xaDataIndex = 0;
 }
 xaData = (XAData)xaDataList.get(xaDataIndex++);
 }
 return xaData;
 }

 public synchronized void failedXAData(XAData xads)
 {
 if(xads.equals(this.xaData))
 {
 this.xaData = null;
 }
 }

 /* URLSelectorStrategy Implementation goes here*/
 public List getCustomSortedUrls()
 {
 return xaDataList;
 }
 public void failedUrlObject(Object urlObject)
 {
 failedXAData((XAData)urlObject);
 }
 public List getAllUrlObjects()
 {
 return xaDataList;
 }
 public Object getUrlObject()
 {
 return getXAData();
 }
 }

http://anonsvn.jboss.org/repos/jbossas/trunk/connector/src/main/org/jboss/resource/adapter/jdbc/xa/XAManagedConnectionFactory.java

[emmitt1219]

Thanks for the help!

How about JBoss 4? Is there any way to accomplish this on 4.0.4...?

[vickyk]

"emmitt1219" wrote:
Thanks for the help!

How about JBoss 4? Is there any way to accomplish this on 4.0.4...?

Not without the code change it is not possible with 4.0.4 , you got to modify
http://anonsvn.jboss.org/repos/jbossas/tags/JBoss_4_0_4_GA/connector/src/main/org/jboss/resource/adapter/jdbc/xa/HAXAManagedConnectionFactory.java

Logically you can create a new resource adapter which would be similar to jboss-ha-local-jdbc.rar but with modified HAXAManagedConectionFactory implementation . But make sure that the changes you made are proper , it is risky unless you know what you are doing ;)

HA jdbc RA's were never designed for load balancing they are there for fail over .

[emmitt1219]

Got it. Thank you for your help!