Combine into a single workflow

Author: dandavison

Diff for: message_passing/introduction/starter.py

@@ -21,26 +21,30 @@ async def main(client: Optional[Client] = None):
         task_queue=TASK_QUEUE,
     )
 
+    # 👉 Send a Query
     supported_languages = await wf_handle.query(
         GreetingWorkflow.get_languages, GetLanguagesInput(include_unsupported=False)
     )
     print(f"supported languages: {supported_languages}")
 
+    # 👉 Execute an Update
     previous_language = await wf_handle.execute_update(
         GreetingWorkflow.set_language, Language.CHINESE
     )
     current_language = await wf_handle.query(GreetingWorkflow.get_language)
     print(f"language changed: {previous_language.name} -> {current_language.name}")
 
+    # 👉 Start an Update and then wait for it to complete
     update_handle = await wf_handle.start_update(
-        GreetingWorkflow.set_language,
-        Language.ENGLISH,
+        GreetingWorkflow.set_language_using_activity,
+        Language.ARABIC,
         wait_for_stage=WorkflowUpdateStage.ACCEPTED,
     )
     previous_language = await update_handle.result()
     current_language = await wf_handle.query(GreetingWorkflow.get_language)
     print(f"language changed: {previous_language.name} -> {current_language.name}")
 
+    # 👉 Send a Signal
     await wf_handle.signal(GreetingWorkflow.approve, ApproveInput(name=""))
     print(await wf_handle.result())
 

Diff for: message_passing/introduction/workflows.py

@@ -2,7 +2,7 @@
 from dataclasses import dataclass
 from datetime import timedelta
 from enum import IntEnum
-from typing import Optional
+from typing import List, Optional
 
 from temporalio import activity, workflow
 from temporalio.exceptions import ApplicationError
@@ -51,14 +51,21 @@ def __init__(self) -> None:
             Language.ENGLISH: "Hello, world",
         }
         self.language = Language.ENGLISH
+        self.lock = asyncio.Lock()  # used by the async handler below
 
     @workflow.run
     async def run(self) -> str:
-        await workflow.wait_condition(lambda: self.approved_for_release)
+        # 👉 In addition to waiting for the `approve` Signal, we also wait for
+        # all handlers to finish. Otherwise, the Workflow might return its
+        # result while an async set_language_using_activity Update is in
+        # progress.
+        await workflow.wait_condition(
+            lambda: self.approved_for_release and workflow.all_handlers_finished()
+        )
         return self.greetings[self.language]
 
     @workflow.query
-    def get_languages(self, input: GetLanguagesInput) -> list[Language]:
+    def get_languages(self, input: GetLanguagesInput) -> List[Language]:
         # 👉 A Query handler returns a value: it can inspect but must not mutate the Workflow state.
         if input.include_unsupported:
             return sorted(Language)
@@ -83,42 +90,9 @@ def validate_language(self, language: Language) -> None:
             # 👉 In an Update validator you raise any exception to reject the Update.
             raise ValueError(f"{language.name} is not supported")
 
-    @workflow.query
-    def get_language(self) -> Language:
-        return self.language
-
-
-@workflow.defn
-class GreetingWorkflowWithAsyncHandler(GreetingWorkflow):
-    """
-    A workflow that that returns a greeting in one of many available languages.
-
-    It supports a Query to obtain the current language, an Update to change the
-    current language and receive the previous language in response, and a Signal
-    to approve the Workflow so that it is allowed to return its result.
-    """
-
-    # 👉 This workflow supports the full range of languages, because the update
-    # handler is async and uses an activity to call a remote service.
-
-    def __init__(self) -> None:
-        super().__init__()
-        self.lock = asyncio.Lock()
-
-    @workflow.run
-    async def run(self) -> str:
-        # 👉 In addition to waiting for the `approve` Signal, we also wait for
-        # all handlers to finish. Otherwise, the Workflow might return its
-        # result while a set_language Update is in progress.
-        await workflow.wait_condition(
-            lambda: self.approved_for_release and workflow.all_handlers_finished()
-        )
-        return self.greetings[self.language]
-
     @workflow.update
-    async def set_language(self, language: Language) -> Language:
-        # 👉 An Update handler can mutate the Workflow state and return a value.
-        # 👉 Since this update handler is async, it can execute an activity.
+    async def set_language_using_activity(self, language: Language) -> Language:
+        # 👉 This update handler is async, so it can execute an activity.
         if language not in self.greetings:
             # 👉 We use a lock so that, if this handler is executed multiple
             # times, each execution can schedule the activity only when the
@@ -143,9 +117,17 @@ async def set_language(self, language: Language) -> Language:
         previous_language, self.language = self.language, language
         return previous_language
 
+    @workflow.query
+    def get_language(self) -> Language:
+        return self.language
+
 
 @activity.defn
 async def call_greeting_service(to_language: Language) -> Optional[str]:
+    """
+    An Activity that simulates a call to a remote greeting service.
+    The remote greeting service supports the full range of languages.
+    """
     greetings = {
         Language.ARABIC: "مرحبا بالعالم",
         Language.CHINESE: "你好，世界",

Diff for: tests/message_passing/introduction/workflow_test.py

@@ -9,7 +9,6 @@
 from message_passing.introduction.workflows import (
     GetLanguagesInput,
     GreetingWorkflow,
-    GreetingWorkflowWithAsyncHandler,
     Language,
     call_greeting_service,
 )
@@ -107,23 +106,18 @@ async def test_set_language_that_is_only_available_via_remote_service(
     async with Worker(
         client,
         task_queue=TASK_QUEUE,
-        workflows=[GreetingWorkflowWithAsyncHandler],
+        workflows=[GreetingWorkflow],
         activities=[call_greeting_service],
     ):
         wf_handle = await client.start_workflow(
-            GreetingWorkflowWithAsyncHandler.run,
+            GreetingWorkflow.run,
             id=str(uuid.uuid4()),
             task_queue=TASK_QUEUE,
         )
-        assert (
-            await wf_handle.query(GreetingWorkflowWithAsyncHandler.get_language)
-            == Language.ENGLISH
-        )
+        assert await wf_handle.query(GreetingWorkflow.get_language) == Language.ENGLISH
         previous_language = await wf_handle.execute_update(
-            GreetingWorkflowWithAsyncHandler.set_language, Language.ARABIC
+            GreetingWorkflow.set_language_using_activity,
+            Language.ARABIC,
         )
         assert previous_language == Language.ENGLISH
-        assert (
-            await wf_handle.query(GreetingWorkflowWithAsyncHandler.get_language)
-            == Language.ARABIC
-        )
+        assert await wf_handle.query(GreetingWorkflow.get_language) == Language.ARABIC