A popular request among users of the Batch module is the ability to grab the job instance id in any of a Batch job’s phases. Why is that useful? Well, there could be a number of useful scenarios:

• If the batch communicates with an external system, it’s sometimes useful to pass the local job instance id for reference and management purposes
• To improve the job’s custom logging
• Some jobs might want to fire email or SMS notifications for meaningful events, having the job instance id in those messages is obviously helpful.

Example

The id will be exposed throw a flow variable of key ‘batchJobInstanceId’. That flow variable will be available since the very beginning of the input phase. It will also be available on every step and in the on-complete phase. Let’s see an example job:

As you see this job is pretty simple. In all its phases, it invokes a sub-flow which logs the output of #[flowVars[‘batchJobInstanceId’]]. The log output that it produces is the following:

INFO  2015-05-08 18:18:09,599 [[batch].HTTP_Listener_Configuration.worker.01] com.mulesoft.module.batch.engine.DefaultBatchEngine: Starting input phase
INFO  2015-05-08 18:18:09,603 [[batch].HTTP_Listener_Configuration.worker.01] org.mule.api.processor.LoggerMessageProcessor: Job Instance Id is: ba01e1a0-f5c7-11e4-9414-10ddb1daeb6d
INFO  2015-05-08 18:18:09,603 [[batch].HTTP_Listener_Configuration.worker.01] com.mulesoft.module.batch.engine.DefaultBatchEngine: Input phase completed
INFO  2015-05-08 18:18:09,608 [[batch].HTTP_Listener_Configuration.worker.01] com.mulesoft.module.batch.engine.queue.BatchQueueLoader: Starting loading phase for instance 'ba01e1a0-f5c7-11e4-9414-10ddb1daeb6d' of job 'batchBatch'
INFO  2015-05-08 18:18:09,610 [[batch].HTTP_Listener_Configuration.worker.01] com.mulesoft.module.batch.engine.queue.BatchQueueLoader: Finished loading phase for instance ba01e1a0-f5c7-11e4-9414-10ddb1daeb6d of job batchBatch. 1 records were loaded
INFO  2015-05-08 18:18:09,615 [[batch].HTTP_Listener_Configuration.worker.01] com.mulesoft.module.batch.engine.DefaultBatchEngine: Started execution of instance 'ba01e1a0-f5c7-11e4-9414-10ddb1daeb6d' of job 'batchBatch'
INFO  2015-05-08 18:18:09,624 [batch-job-batchBatch-work-manager.01] org.mule.api.processor.LoggerMessageProcessor: Job Instance Id is: ba01e1a0-f5c7-11e4-9414-10ddb1daeb6d
INFO  2015-05-08 18:18:09,643 [batch-job-batchBatch-work-manager.01] com.mulesoft.module.batch.engine.DefaultBatchEngine: Starting execution of onComplete phase for instance ba01e1a0-f5c7-11e4-9414-10ddb1daeb6d of job batchBatch
INFO  2015-05-08 18:18:09,644 [batch-job-batchBatch-work-manager.01] org.mule.api.processor.LoggerMessageProcessor: Job Instance Id is: ba01e1a0-f5c7-11e4-9414-10ddb1daeb6d
INFO  2015-05-08 18:18:09,644 [batch-job-batchBatch-work-manager.01] com.mulesoft.module.batch.engine.DefaultBatchEngine: Finished execution of onComplete phase for instance ba01e1a0-f5c7-11e4-9414-10ddb1daeb6d of job batchBatch
INFO  2015-05-08 18:18:09,644 [batch-job-batchBatch-work-manager.01] com.mulesoft.module.batch.engine.DefaultBatchEngine: Finished execution for instance 'ba01e1a0-f5c7-11e4-9414-10ddb1daeb6d' of job 'batchBatch'. Total Records processed: 1. Successful records: 1. Failed Records: 0

So that’s it. This is a small, easy to use improvement which I hope you’ll find useful. Have any other examples of how the job instance id can be useful? Please share!