Data exchange in executions

See also

Data exchange SWF documentation

SWF will always pass around strings for workflow and activity input and result, however seddy will always JSON-deserialise it during processing. To get an arbitrary string as input or result, simply provide a JSON string, eg "foo: bar" (ie include the double-quotes in the string).

DAG-type workflows result

The workflow result is built from the task results. Specifically, the task ID is used as the key, the task’s result as the value.

For example, a workflow with task IDs “task1”, “task2”, “task3” and “task4” could have execution result:

{"task1": "eggs", "task3": null, "task4": {"c": [1, 2]}}

Note that a task won’t have a corresponding entry in the workflow result if the task doesn’t provide a result.

Basic single-valued JSONPath

This is a subset of the JSONPath syntax, where only one value is to be retrieved, and no functions are performed. The format rules are:

  • must start with $, for the root item

  • object keys are prefixed by .

  • array indices are enclosed by [ and ]

  • child items are specified to the right

For example, suppose with the item

{"eggs": [{"spam": {"swallow": [null, null, 42]}}]}

Then the JSONPath $.eggs[0].spam.swallow[2] would give 42, and the JSONPath $.eggs[0].spam would give {"swallow": [null, null, 42]}.