Hi All, I'd like to revisit a topic that came up not too long ago about communicating a task's completion status back to its parent workflow. I just want to make sure I understand what other folks are doing to handle this before I go down a rabbit hole trying to invent a way to do it.
I have been investigating the workflow manager code to see what capabilities are already built-in and what are not. I have just a simple sequential workflow, so, I have really only investigated the workflow manager from the ThreadPoolWorkflowEngine and IterativeWorkflowProcessorThread point of view. I looked to find all of the places where something is setting or getting any type of 'status' value or lifecycle stage type of value. And I have some questions related to what I found. I found that a workflow will stop executing tasks if any of its tasks require a specific metadata key and value to be present in the shared metadata, but that key and value are not present. If this occurs, the workflow instance status is set to METADATA_MISSING and is updated in the workflow instance repository and then the workflow stops iterating through the list of tasks. This is the only error condition I could find that will cause a workflow to stop executing. There does exist a workflow status called "ERROR", but I could not find any place where the workflow status is being set to "ERROR" or anyplace where the workflow status is being checked to see if it is equal to "ERROR". So, it looks like workflow manager is very "success oriented". Which is fine. But for me it raises the question how are people accounting for errors that might occur during execution of a workflow that might require the workflow to stop or not execute one of its tasks? For example, let's say if task "abc" fails, and you want workflow manager to continue with the next task, but you don't want workflow manager to run task "xyz" which is further down the task list. Is anyone out there doing anything to handle this type of situation? And if so, please tell me what approach you took to implement your logic to handle it. I am really hoping that someone else has explored this area before me J (Right now, it is looking like I would need to write my own IterativeWorkflowProcessorThread and build the logic into it, but that is a rabbit hole I don't want to go down.) I should note that I am using the word "task" to mean both a PGE Task and a non-PGE task. I realize that the 'exe' section inside of a PGE Task gives you the freedom to write scripts that do check returned values from different commands that are in the script. But, I'm really trying to ask about the communication of statuses that exist at a layer above the PGE Task. Thanks for your help! Val Valerie A. Mallder New Horizons Deputy Mission System Engineer The Johns Hopkins University/Applied Physics Laboratory 11100 Johns Hopkins Rd (MS 23-282), Laurel, MD 20723 240-228-7846 (Office) 410-504-2233 (Blackberry)
