private void validateJobDeployment() {
		// Double check so that user gets an informative error message
		JobDefinition job = definitionRepository.findOne(jobName);
		if (job == null) {
			throw new NoSuchDefinitionException(jobName,
					String.format("There is no %s definition named '%%s'", "job"));
		}
		if (instanceRepository.findOne(jobName) == null) {
			throw new NotDeployedException(jobName, String.format("The %s named '%%s' is not currently deployed",
					"job"));
		}
	}
Uses the {@link MessageBus} to execute a job deployed in a Spring XD cluster.

@param contribution The contribution to the step's metrics.  Not used in this case
@param chunkContext Used to get a handle on the JobExecution and JobInstance
@return RepeatStatus.FINISHED
@throws Exception
spring-xd-dirt/src/main/java/org/springframework/xd/dirt/batch/tasklet/JobLaunchingTasklet.java