Chains

If we want to combine multiple logically-connected jobs or tasks, we should build a job chain. As the name implies, a chain is simply a group of concurrent or sequential jobs. Tasks that have no relation to the other tasks should be scheduled individually, and not as a part of a job chain.

In other words, an individual task can get skipped because another part in the chain has been skipped.

Clearly, skipping tasks in any chain is probably not something we want. In a job that consists of multiple steps, we want to see some kind of relationship between the steps. We describe this relationship with rules. The rules in a chain define the order in which the job steps are executed (or, maybe, not executed). Execution depends on the status of the previous job steps. Let's list the statuses and their meanings.