Automatically serialize/deserialize activity/suborchestrator arguments and return values #90
Description
Looking at the fan out fan in example, there are are a few places where we have to manually serialize/deserialize data that we should eliminate.
When call_activity is called, we automatically serialize the input value to a string (for example, we serialize the int to a str here). However, in the activity function itself, we need to explicitly convert the value back.
When we return a value from an activity, we require manual serialization. And in the orchestrator, we manually deserialize it.
Proposed changes:
- Always deserialize input values for activity functions.
- Always serialize return values for activity functions.
- Always deserialize values returned by the task from
call_activity(and the othercall_activityandcall_suborchestratorvariants). - Always serialize input value in
start_new(looks like we already do this) - Always deserialize
get_input
Some questions:
- What do we do with type hints? (It appears we currently ignore the type hint for an activity function input and always pass a string, as demonstrated here)
- Do we support deserialization to custom classes or stick to primitives like
str,int,float,list,dict, etc (whateverjson.loadssupports)?
The changes will allow the orchestrator code to the written like this:
def orchestrator_function(context: df.DurableOrchestrationContext):
activity_list = yield context.call_activity("GetActivityCount", 5)
tasks = [context.call_activity("ParrotValue", i) for i in activity_list]
values = yield context.task_all(tasks)
message = yield context.call_activity("ShowMeTheSum", values)
return messageThe activity function would then look like this:
def main(value: int) -> list:
activity_values = [*range(value)]
return activity_valuesWe should be able to remove all import json statements from orchestrators and activities except when we're really working with JSON data.