Complex investigation, easy solution

Yesterday I was facing one production issue where somehow at some time the connection to a database which is located at another server will be reset. I was getting java.lang.SqlException(io exception: connection resrt). I have reused a method that will reconnect to the database. I hope it works in the next deployment and i believe it should work. Code snippet as below:

public Connection getDBConnection(String dbName) throws OracleConnException, Exception { if (logger.isInfoEnabled()) { logger.info("getDBConnection(String) - String dbName=" + dbName); //$NON-NLS-1$ } Connection cachedConnection = null; if (ocDataSource == null) { ocDataSource = new HashMap(); this.printSQL("new HashMap"); } OracleDataSource ds = (OracleDataSource) ocDataSource.get(dbName); if(ds == null){ this.printSQL("creatingNewOracleDS"); ds = createNewOracleDS(dbName); this.printSQL("createdNewOracleDS"); ocDataSource.put(dbName.trim(), ds); } int i = 0; int retry = KenanAdaptorProperties.getORACLE_RETRY_NUM(); for(i = 0; i < retry; i++){ try { this.printSQL("ds.getConnection() " + ds.getPortNumber()); cachedConnection = ds.getConnection(); this.printSQL("error in connection? "); if(!isConnectionAlive(cachedConnection)){ this.printSQL("connection is not alive???"); try { ds.close(); } catch(Exception e){ //log.debug("Can't close DataSource object!"); } ds = null; ocDataSource.remove(dbName); ds = createNewOracleDS(dbName); ocDataSource.put(dbName, ds); } else { break; } } catch (SQLException se){ logger.error("getDBConnection(String)", se); //$NON-NLS-1$ } catch (Exception e){ this.printSQL("Exception:\r\n" + Util.getStackTraceForLog(e)); } // sleep for a specific amount of time! //make it configurable try { Thread.sleep(KenanAdaptorProperties.getORACLE_RETRY_SLEEP_TIME()); } catch (InterruptedException e) { // log.debug("Interrupted Exception:\r\n" + Util.getStackTraceForLog(e)); } } if(i == retry){ throw new OracleConnException("Connection is not established. Failed after " + retry + " retries."); } return cachedConnection; }

production rollout for Kenan Adapter running on Websphere Business Integration Adapters is successful!

Finally the production rollout for Kenan Adapter is successful!

This is the third deployment after the unsuccessful first two. Well it went well in spite of some minor issues. Most of the scenarios are catered this time. The client's testing team had done a good job this time for testing thoroughly on all kind of possible scenarios! Yeah they should have done that during the UAT time! If they would allocate some time for more scenario testing, the deployment would have gone well even before year 2009! No it's approaching March and the client only managed to use it now. Well, this project does not bring any income to my team anyway. My project manager took this project to cover up some other unit's shit. Now that the long term outsource deal has been closed.

I am studying Websphere Process Server now. It looks far more complicated. I think i need some time to digest some new terms here. I should get myself involved in at least one project related to this product so that i can gain more expertise in this product.

All in all, good news this week. I am glad especially for the successfull rollout for Kenan Adapter. I have put very much effort in making this successful. I would like to thank my project manager for the support! That is important to continue to boost my morale.

Something funny has happened!

I am not sure why. Somehow the XML message that was passed to my request queue contains response tag which is not supposed to be attached to it.

What annoyed me was my WBI adapter for Kenan kept processing the same XML message over and over again! Thank to this and only i found out that there was one database connection remained opened thus causing more and more database sessions created!!! This could be a serious issue and luckily i tackled the problem before the system goes for production! However, i still need to find out why sometimes the XML message is redirected to the request queue even tough it has been processed by the adapter without encountering any Tuxedo connection error! The only clue i know now is this kind of 'problematic' XML message contains response tag! Could it be an error from the portal side? Could it be they acquired the processed XML message from response queue and then sent to request queue again? Well, it is doubtful.

Scratching head... continue tomorrow....

The Jar Manifest

Today i learned something about the Manifest file inside JAR file.

I found out that path for the Class-Path property starts from the path where the jar is located.

For example, if you place your JAR file at C:/myApp/service/myJar.jar, and you want to add a library (C:/myApp/lib/A.jar) to your manifest file, you will NOT be able to achieve that! Remember this!

The root path for the Class-Path property in the manifest.mf file starts with the path where the jar file installed.

In this case, if you want to put your classes into manifest.mf, you have to move the C:/myApp/lib/ to C:/myApp/service/lib

Correct me if i am wrong.

BEA Tuxedo Hack

I had a tricky problem with the Wepshere Business Integration(WBI) Adaptor. There was a error message saying that the jar file in my customized adaptor (tuxedo.jar) failed to load a 'so' file. It uses loadFile method from java.lang.System and somehow that particular file could not be found. I double checked the LIB_PATH(AIX machine) and java.lib.property and they are correct.

In the end i decompiled the particular class from the tuxedo.jar, modified the source code by using load method in java.lang.System instead of loadFile method. The load method will require us to specify the absolute file path. It works!!!

IBM Websphere Business Integrator Adapter

My recent work is much on maintaining an adapter called Kenan Adapter deployed on an IBM product called IBM Websphere Business Integrator(WBI). This product basically picks up XML message in the queue and processes the particular messages. I was struggling on getting the web services call to work. I tried a few methods but the web services call just did not work. My project manager who has a very solid technical background could not provide a solution too. In the end he concluded that an RMI program cannot just call another RMI. The WBI framework itself is RMI based. Hence he helped me to build a standalone Java application that listens to the queue all the time, picks up messages then calls the web services. Last Friday i tested one round. The web service call was successful!

About Hibernate Save and Delete parent children again

I want to add new child object into children collections and remove 'selected' existing child object from the same children collections.

1. First, i get the collection from 'attached' parent. For e.g Set children = parent.getChildren()
2. Add the new Child object. Of course please save the Child object first. children.add(newChild).
3. Remove the 'selected' existing Child object. children.remove(removedChild)
4. Finally, save the Parent object.

It is kind of fundamental. However sometimes we may get confused due to whatever reasons.