Added async workflow client implementation, leveraging new durabletask.aio.client implementation

examples/workflow/README.md

@@ -85,6 +85,73 @@ The output of this example should look like this:
   - "== APP == Workflow completed! Result: Completed"
 ```
 
+### Simple Workflow Async
+This example represents a workflow with async activities and using the async WorkflowClient that manages counters through a series of activities and child workflows.
+It shows several Dapr Workflow features including:
+- Basic activity execution with counter increments
+- Retryable activities with configurable retry policies
+- Child workflow orchestration with retry logic
+- External event handling with timeouts
+- Workflow state management (pause/resume)
+- Activity error handling and retry backoff
+- Global state tracking across workflow components
+- Workflow lifecycle management (start, pause, resume, purge)
+
+
+<!--STEP
+name: Run the simple async workflow example
+expected_stdout_lines:
+  - "== APP == Hi Counter!"
+  - "== APP == New counter value is: 1!"
+  - "== APP == New counter value is: 11!"
+  - "== APP == Retry count value is: 0!"
+  - "== APP == Retry count value is: 1! This print statement verifies retry"
+  - "== APP == Appending 1 to child_orchestrator_string!"
+  - "== APP == Appending a to child_orchestrator_string!"
+  - "== APP == Appending a to child_orchestrator_string!"
+  - "== APP == Appending 2 to child_orchestrator_string!"
+  - "== APP == Appending b to child_orchestrator_string!"
+  - "== APP == Appending b to child_orchestrator_string!"
+  - "== APP == Appending 3 to child_orchestrator_string!"
+  - "== APP == Appending c to child_orchestrator_string!"
+  - "== APP == Appending c to child_orchestrator_string!"
+  - "== APP == Get response from hello_world_wf after pause call: SUSPENDED"
+  - "== APP == Get response from hello_world_wf after resume call: RUNNING"
+  - "== APP == New counter value is: 111!"
+  - "== APP == New counter value is: 1111!"
+  - "== APP == Workflow completed! Result: Completed"
+timeout_seconds: 30
+-->
+
+```sh
+dapr run --app-id wf-simple-aio-example -- python3 simple_aio.py
+```
+<!--END_STEP-->
+
+The output of this example should look like this:
+
+```
+  - "== APP == Hi Counter!"
+  - "== APP == New counter value is: 1!"
+  - "== APP == New counter value is: 11!"
+  - "== APP == Retry count value is: 0!"
+  - "== APP == Retry count value is: 1! This print statement verifies retry"
+  - "== APP == Appending 1 to child_orchestrator_string!"
+  - "== APP == Appending a to child_orchestrator_string!"
+  - "== APP == Appending a to child_orchestrator_string!"
+  - "== APP == Appending 2 to child_orchestrator_string!"
+  - "== APP == Appending b to child_orchestrator_string!"
+  - "== APP == Appending b to child_orchestrator_string!"
+  - "== APP == Appending 3 to child_orchestrator_string!"
+  - "== APP == Appending c to child_orchestrator_string!"
+  - "== APP == Appending c to child_orchestrator_string!"
+  - "== APP == Get response from hello_world_wf after pause call: SUSPENDED"
+  - "== APP == Get response from hello_world_wf after resume call: RUNNING"
+  - "== APP == New counter value is: 111!"
+  - "== APP == New counter value is: 1111!"
+  - "== APP == Workflow completed! Result: Completed"
+```
+
 ### Task Chaining
 
 This example demonstrates how to chain "activity" tasks together in a workflow. You can run this sample using the following command:

examples/workflow/simple_aio.py

@@ -0,0 +1,177 @@
+# -*- coding: utf-8 -*-
+# Copyright 2025 The Dapr Authors
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#     http://www.apache.org/licenses/LICENSE-2.0
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import asyncio
+from datetime import timedelta
+
+import dapr.ext.workflow as wf
+from dapr.ext.workflow.aio import DaprWorkflowClient, WorkflowRuntime
+
+from dapr.clients.exceptions import DaprInternalError
+from dapr.conf import Settings
+
+settings = Settings()
+
+counter = 0
+retry_count = 0
+child_orchestrator_count = 0
+child_orchestrator_string = ''
+child_act_retry_count = 0
+instance_id = 'exampleInstanceID'
+child_instance_id = 'childInstanceID'
+workflow_name = 'hello_world_wf'
+child_workflow_name = 'child_wf'
+input_data = 'Hi Counter!'
+event_name = 'event1'
+event_data = 'eventData'
+non_existent_id_error = 'no such instance exists'
+
+
+retry_policy = wf.RetryPolicy(
+    first_retry_interval=timedelta(seconds=1),
+    max_number_of_attempts=3,
+    backoff_coefficient=2,
+    max_retry_interval=timedelta(seconds=10),
+    retry_timeout=timedelta(seconds=100),
+)
+
+asyncio.set_event_loop(asyncio.new_event_loop())
+loop = asyncio.get_event_loop()
+wfr = WorkflowRuntime(main_event_loop=loop)
+
+
+# workflow still synchronous. Not expected to run any async code.
+@wfr.workflow(name='hello_world_wf')
+def hello_world_wf(ctx: wf.DaprWorkflowContext, wf_input):
+    print(f'{wf_input}')
+    yield ctx.call_activity(hello_act, input=1)
+    yield ctx.call_activity(hello_act, input=10)
+    yield ctx.call_activity(hello_retryable_act, retry_policy=retry_policy)
+    yield ctx.call_child_workflow(child_retryable_wf, retry_policy=retry_policy)
+
+    # Change in event handling: Use when_any to handle both event and timeout
+    event = ctx.wait_for_external_event(event_name)
+    timeout = ctx.create_timer(timedelta(seconds=30))
+    winner = yield wf.when_any([event, timeout])
+
+    if winner == timeout:
+        print('Workflow timed out waiting for event')
+        return 'Timeout'
+
+    yield ctx.call_activity(hello_act, input=100)
+    yield ctx.call_activity(hello_act, input=1000)
+    return 'Completed'
+
+
+# activity is async and will be executed on the main event loop.
+@wfr.activity(name='hello_act')
+async def hello_act(ctx: wf.WorkflowActivityContext, wf_input):
+    global counter
+    counter += wf_input
+    await asyncio.sleep(0.1)  # simulates async work.
+    print(f'New counter value is: {counter}!', flush=True)
+
+
+# an activity can also be left synchronous.
+@wfr.activity(name='hello_retryable_act')
+def hello_retryable_act(ctx: wf.WorkflowActivityContext):
+    global retry_count
+    if (retry_count % 2) == 0:
+        print(f'Retry count value is: {retry_count}!', flush=True)
+        retry_count += 1
+        raise ValueError('Retryable Error')
+    print(f'Retry count value is: {retry_count}! This print statement verifies retry', flush=True)
+    retry_count += 1
+
+
+# workflow still synchronous. Not expected to run any async code.
+@wfr.workflow(name='child_retryable_wf')
+def child_retryable_wf(ctx: wf.DaprWorkflowContext):
+    global child_orchestrator_string, child_orchestrator_count
+    if not ctx.is_replaying:
+        child_orchestrator_count += 1
+        print(f'Appending {child_orchestrator_count} to child_orchestrator_string!', flush=True)
+        child_orchestrator_string += str(child_orchestrator_count)
+    yield ctx.call_activity(
+        act_for_child_wf, input=child_orchestrator_count, retry_policy=retry_policy
+    )
+    if child_orchestrator_count < 3:
+        raise ValueError('Retryable Error')
+
+
+@wfr.activity(name='act_for_child_wf')
+async def act_for_child_wf(ctx: wf.WorkflowActivityContext, inp):
+    global child_orchestrator_string, child_act_retry_count
+    inp_char = chr(96 + inp)
+    print(f'Appending {inp_char} to child_orchestrator_string!', flush=True)
+    child_orchestrator_string += inp_char
+    if child_act_retry_count % 2 == 0:
+        child_act_retry_count += 1
+        raise ValueError('Retryable Error')
+    child_act_retry_count += 1
+
+
+async def main():
+    wfr.start()
+    wf_client = DaprWorkflowClient()
+
+    print('==========Start Counter Increase as per Input:==========')
+    await wf_client.schedule_new_workflow(
+        workflow=hello_world_wf, input=input_data, instance_id=instance_id
+    )
+
+    await wf_client.wait_for_workflow_start(instance_id)
+
+    # Sleep to let the workflow run initial activities
+    await asyncio.sleep(12)
+
+    assert counter == 11
+    assert retry_count == 2
+    assert child_orchestrator_string == '1aa2bb3cc'
+
+    # Pause Test
+    await wf_client.pause_workflow(instance_id=instance_id)
+    metadata = await wf_client.get_workflow_state(instance_id=instance_id)
+    print(f'Get response from {workflow_name} after pause call: {metadata.runtime_status.name}')
+
+    # Resume Test
+    await wf_client.resume_workflow(instance_id=instance_id)
+    metadata = await wf_client.get_workflow_state(instance_id=instance_id)
+    print(f'Get response from {workflow_name} after resume call: {metadata.runtime_status.name}')
+
+    await asyncio.sleep(2)  # Give the workflow time to reach the event wait state
+    await wf_client.raise_workflow_event(
+        instance_id=instance_id, event_name=event_name, data=event_data
+    )
+
+    print('========= Waiting for Workflow completion', flush=True)
+    try:
+        state = await wf_client.wait_for_workflow_completion(instance_id, timeout_in_seconds=30)
+        if state.runtime_status.name == 'COMPLETED':
+            print('Workflow completed! Result: {}'.format(state.serialized_output.strip('"')))
+        else:
+            print(f'Workflow failed! Status: {state.runtime_status.name}')
+    except TimeoutError:
+        print('*** Workflow timed out!')
+
+    await wf_client.purge_workflow(instance_id=instance_id)
+    try:
+        await wf_client.get_workflow_state(instance_id=instance_id)
+    except DaprInternalError as err:
+        if non_existent_id_error in err._message:
+            print('Instance Successfully Purged')
+
+    wfr.shutdown()
+
+
+if __name__ == '__main__':
+    loop.run_until_complete(main())

ext/dapr-ext-workflow/dapr/ext/workflow/aio/__init__.py

@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+
+"""
+Copyright 2025 The Dapr Authors
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+from .dapr_workflow_client import DaprWorkflowClient
+from .workflow_runtime import WorkflowRuntime
+
+__all__ = [
+    'DaprWorkflowClient',
+    'WorkflowRuntime',
+]