My workspace

A few years ago in one of my blog post , i described how to use Oracle database changed notification to update HazelCast cache in application server layer. For now this is one of the finest use case of using Oracle database changed notification, but you can also use this possibilities for solving others problem such as event processing in legacy table. For instance, you are developing dispute system for any Banking system. For banking core system, dispute is as a another banking transaction, when any dispute comes from any client, operator of bank should react on this transaction. Most of the time disputes keeps in same storage (tables) along with another transactions. Such type of tables can keeps billions of rows, and when you would like to get notified when a few of the rows changes, you have a few options in your hand: 1) Poll periodically, schedular which will poll the whole table periodically to get changed data. 2) Using oracle trigger to send some notification (stored procedu...

Most modern distributed systems somewhere comes across the problem where only one instance of the process or job should runs and others instance of the same job or process should be standby. Apache zookeeper project provides this above functionality out of box. I am not going to describe all the usecases or solutions that could be solved by the Zookeeper. You can read the following great article for quick start. Let me describe our use case with more details, we have apache camel component which polling some resources and only one instance of the component should run in any time. It means there should be one leader and a few followers. When master or leader goes down, any follower should replace the master. You also can use doozerd instead of zookeeper for leader election, but for me zookeeper is easy to maintain. It's very easy to install a multi server zookeeper cluster. I have recommend you to follow the step from this blog to setup a cluster. Now when we have done our cl...