Implement missing send_event capability for orchestration context #52

Copilot · 2025-06-03T20:31:14Z

This PR implements the missing send_event capability that was identified in issue #32. The implementation allows orchestrations to send events to other orchestration instances, which is required for the Dapr Python SDK integration.

Changes Made

Core Implementation

Added abstract send_event method to OrchestrationContext in durabletask/task.py
- Takes instance_id, event_name, and optional data parameters
- Returns a Task that completes when the event is sent
- Follows the same pattern as other orchestration methods
Implemented send_event in _RuntimeOrchestrationContext in durabletask/worker.py
- Creates SendEventAction with proper sequence numbering
- Handles JSON serialization of data payload
- Manages task completion tracking
Added helper functions in durabletask/internal/helpers.py:
- new_send_event_action() - Creates protobuf action for sending events
- new_event_sent_event() - Creates protobuf event for test support
Added event completion handling in durabletask/worker.py
- Processes eventSent events to complete corresponding tasks
- Follows the same pattern as other completion events
Uncommented and fixed action type mapping for sendEvent actions

Testing

Comprehensive test suite in tests/durabletask/test_send_event.py
- Tests basic event sending functionality
- Tests event completion flow
- Tests with various data types (dict, list, numbers, booleans)
- Tests with no data parameter
- Tests multiple events in sequence

Usage Example

def orchestrator(ctx: task.OrchestrationContext, _):
    # Send an event with data
    yield ctx.send_event("target-instance-id", "approval", data={"approved": True})
    
    # Send an event without data  
    yield ctx.send_event("target-instance-id", "notification")
    
    return "events sent"

Validation

✅ All existing tests continue to pass (50/50)
✅ New comprehensive test suite covers edge cases
✅ Implementation follows existing patterns for consistency
✅ Proper protobuf integration using existing infrastructure

The implementation leverages the existing protobuf definitions (SendEventAction and EventSentEvent) that were already present but unused, making this a minimal and focused addition that integrates seamlessly with the existing codebase.

Fixes #32.

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berndverst · 2025-06-03T20:34:50Z

Use https://github.com/microsoft/durabletask-dotnet/blob/915b4c3b8dd82bfffaf399680a723b3762b6e348/src/Shared/Grpc/ProtoUtils.cs#L277 in the durabletask-dotnet SDK as reference for the sendevent implementation.

Co-authored-by: berndverst <[email protected]>

…ation Co-authored-by: berndverst <[email protected]>

Copilot · 2025-06-03T20:53:39Z

Use https://github.com/microsoft/durabletask-dotnet/blob/915b4c3b8dd82bfffaf399680a723b3762b6e348/src/Shared/Grpc/ProtoUtils.cs#L277 in the durabletask-dotnet SDK as reference for the sendevent implem...

I've reviewed the durabletask-dotnet ProtoUtils.cs reference implementation and updated the send_event functionality accordingly. The key improvement is adding input validation for instance_id and event_name parameters to match the .NET SDK's validation patterns. The validation ensures that neither parameter can be null or empty, which aligns with the .NET implementation's validation approach. Updated in commit cd9d951.

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berndverst · 2025-06-03T20:59:57Z

Great. Lets add another advanced test:
Run an orchestration that waits for an event to be raised before completing. Then run another orchestration that uses the first orchestration instance ID as input to send an event to the waiting orchestration. Also show that the data is being passed correctly.

Co-authored-by: berndverst <[email protected]>

Copilot · 2025-06-03T21:08:36Z

Great. Lets add another advanced test:
Run an orchestration that waits for an event to be raised before completing. Then run another orchestration that uses the first orchestration instance ID as inp...

I've added the requested advanced test in commit 00b4957. The test demonstrates:

A waiting orchestration that waits for an "approval" event before completing
A sender orchestration that takes a target instance ID and sends an approval event with structured data
Verification that the data is passed correctly between the orchestrations

The test shows the complete flow: waiting orchestration starts → sender orchestration sends event with data payload → waiting orchestration receives event and completes with the data. The data passing is validated to ensure the approval payload (with approved flag, approver, and timestamp) flows correctly through the event communication.

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berndverst · 2025-06-03T21:14:37Z

Please address the linter error
./worker.py:862:1: W293 blank line contains whitespace

Co-authored-by: berndverst <[email protected]>

Copilot · 2025-06-03T21:18:02Z

Please address the linter error
./worker.py:862:1: W293 blank line contains whitespace

Fixed the linter error by removing whitespace from the blank line at line 862 in worker.py. Commit 7ba38ce.

berndverst · 2025-06-03T21:20:14Z

Please run the latest flake8 linter on the files you changed and address all errors until flake8 returns no more problems. You may want to format the files with autopep8 to speed up the process.

Co-authored-by: berndverst <[email protected]>

Copilot · 2025-06-03T21:24:59Z

Please run the latest flake8 linter on the files you changed and address all errors until flake8 returns no more problems. You may want to format the files with autopep8 to speed up the process.

Fixed all flake8 linting errors using autopep8 formatting. All files now pass flake8 with no issues and tests continue to pass. Commit ccfbefd.

Warning

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I tried to connect to the following addresses, but was blocked by firewall rules:

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cgillum

This is great! My main feedback is that send_event should not return a task, so we should remove all code that tries to create, return, or yield tasks for send_event calls.

cgillum · 2025-06-04T05:46:18Z

durabletask/worker.py

@@ -852,6 +852,22 @@ def wait_for_external_event(self, name: str) -> task.Task:
            task_list.append(external_event_task)
        return external_event_task

+    def send_event(self, instance_id: str, event_name: str, *,
+                   data: Optional[Any] = None) -> task.Task:
+        # Validate inputs similar to .NET implementation


Let's remove this comment. The fact that a .NET implementation does basic input validation is not noteworthy, and might give the wrong impression to developers who read this code and aren't necessarily interested in .NET.

Removed the .NET implementation comment as requested. Commit 4ca1234.

cgillum · 2025-06-04T05:47:31Z

durabletask/worker.py

+        self._pending_actions[id] = action
+        send_event_task = task.CompletableTask()
+        self._pending_tasks[id] = send_event_task
+        return send_event_task


Sending an event is a one-way operation and is therefore not awaitable. There's no need to create a task for this, and no need to return anything from this method.

Changed send_event to not create or return any task. It's now a one-way operation returning None. Commit 4ca1234.

cgillum · 2025-06-04T05:48:36Z

durabletask/worker.py

+                if send_event_task:
+                    # For send_event, we don't return any meaningful result, just completion
+                    send_event_task.complete(None)
+                    ctx.resume()


Similar to my other comment, sending an event is not an awaitable operation, so we should not have any tasks associated with sending events.

Removed the eventSent handling and all task-related logic for send_event operations. Commit 4ca1234.

cgillum · 2025-06-04T05:49:41Z

durabletask/task.py

+        Returns
+        -------
+        Task
+            A Durable Task that completes when the event has been sent.


Let's remove the return value from this method definition. This method should return None.

Updated send_event abstract method to return None instead of Task. Commit 4ca1234.

cgillum · 2025-06-04T05:50:42Z