Messages as MicroServices (#1185)

* Purpose:  Allow the messages api endpoint to accept arbitrary JSON in it's body - and to respond with the latest task_data - this will allow you to create BPMN processes are that can function as microservices.

* Fixing a bug that prevented the synchronous execution of a message post.
* A message post directly uses the body of the post, do not specify it within a "payload".
* The message response is not just the process instance details, it now contains the "process_instance" and "task_data" at the top level of the returned json.
* The last completed task data is now returned as a part of a response to the message api endpoint, it is with the "task_data" attribute.

* CodeRabbit suggestions

* run_pyl fixes

* fix lint

---------

Co-authored-by: burnettk <burnettk@users.noreply.github.com>

spiffworkflow-backend/src/spiffworkflow_backend/models/process_instance.py

@@ -7,6 +7,7 @@ from flask_sqlalchemy.query import Query
 from marshmallow import INCLUDE
 from marshmallow import Schema
 from sqlalchemy import ForeignKey
+from sqlalchemy import desc
 from sqlalchemy.orm import relationship
 from sqlalchemy.orm import validates
 
@@ -198,6 +199,18 @@ class ProcessInstanceModel(SpiffworkflowBaseDBModel):
     def immediately_runnable_statuses(cls) -> list[str]:
         return ["not_started", "running"]
 
+    def get_data(self) -> dict:
+        """Returns the data of the last completed task in this process instance."""
+        last_completed_task = (
+            TaskModel.query.filter_by(process_instance_id=self.id, state="COMPLETED")
+            .order_by(desc(TaskModel.end_in_seconds))  # type: ignore
+            .first()
+        )
+        if last_completed_task:  # pragma: no cover
+            return last_completed_task.json_data()  # type: ignore
+        else:
+            return {}
+
 
 class ProcessInstanceModelSchema(Schema):
     class Meta:

spiffworkflow-backend/src/spiffworkflow_backend/routes/messages_controller.py

@@ -67,22 +67,13 @@ def message_send(
     body: dict[str, Any],
     execution_mode: str | None = None,
 ) -> flask.wrappers.Response:
-    if "payload" not in body:
-        raise (
-            ApiError(
-                error_code="missing_payload",
-                message="Please include a 'payload' in the JSON body that contains the message contents.",
-                status_code=400,
-            )
-        )
-
     process_instance = None
 
     # Create the send message
     message_instance = MessageInstanceModel(
         message_type="send",
         name=message_name,
-        payload=body["payload"],
+        payload=body,
         user_id=g.user.id,
     )
     db.session.add(message_instance)
@@ -110,8 +101,12 @@ def message_send(
         )
 
     process_instance = ProcessInstanceModel.query.filter_by(id=receiver_message.process_instance_id).first()
+    response_json = {
+        "task_data": process_instance.get_data(),
+        "process_instance": ProcessInstanceModelSchema().dump(process_instance),
+    }
     return Response(
-        json.dumps(ProcessInstanceModelSchema().dump(process_instance)),
+        json.dumps(response_json),
         status=200,
         mimetype="application/json",
     )

spiffworkflow-backend/src/spiffworkflow_backend/services/message_service.py

@@ -90,9 +90,7 @@ class MessageService:
             message_instance_receive.status = "running"
 
             cls.process_message_receive(
-                receiving_process,
-                message_instance_receive,
-                message_instance_send,
+                receiving_process, message_instance_receive, message_instance_send, execution_mode=execution_mode
             )
             message_instance_receive.status = "completed"
             message_instance_receive.counterpart_id = message_instance_send.id
@@ -146,13 +144,7 @@ class MessageService:
             cls._cancel_non_matching_start_events(processor_receive, message_triggerable_process_model)
             processor_receive.save()
 
-        if not queue_process_instance_if_appropriate(
-            process_instance_receive, execution_mode=execution_mode
-        ) and not ProcessInstanceQueueService.is_enqueued_to_run_in_the_future(process_instance_receive):
-            execution_strategy_name = None
-            if execution_mode == ProcessInstanceExecutionMode.synchronous.value:
-                execution_strategy_name = "greedy"
-            processor_receive.do_engine_steps(save=True, execution_strategy_name=execution_strategy_name)
+        processor_receive.do_engine_steps(save=True)
 
         return process_instance_receive
 
@@ -195,6 +187,7 @@ class MessageService:
         process_instance_receive: ProcessInstanceModel,
         message_instance_receive: MessageInstanceModel,
         message_instance_send: MessageInstanceModel,
+        execution_mode: str | None = None,
     ) -> None:
         correlation_properties = []
         for cr in message_instance_receive.correlation_rules:
@@ -216,7 +209,15 @@ class MessageService:
         )
         processor_receive = ProcessInstanceProcessor(process_instance_receive)
         processor_receive.bpmn_process_instance.send_event(bpmn_event)
-        processor_receive.do_engine_steps(save=True)
+        execution_strategy_name = None
+
+        if not queue_process_instance_if_appropriate(
+            process_instance_receive, execution_mode=execution_mode
+        ) and not ProcessInstanceQueueService.is_enqueued_to_run_in_the_future(process_instance_receive):
+            execution_strategy_name = None
+            if execution_mode == ProcessInstanceExecutionMode.synchronous.value:
+                execution_strategy_name = "greedy"
+            processor_receive.do_engine_steps(save=True, execution_strategy_name=execution_strategy_name)
         message_instance_receive.status = MessageStatuses.completed.value
         db.session.add(message_instance_receive)
         db.session.commit()

spiffworkflow-backend/tests/spiffworkflow_backend/integration/test_messages.py

@@ -42,15 +42,20 @@ class TestMessages(BaseTest):
         with pytest.raises(ApiError):
             message_send(
                 "Approval Result",
-                {"payload": {"po_number": 1001, "customer_id": "jon"}},
+                {"po_number": 1001, "customer_id": "jon"},
             )
 
         # No error when calling with the correct parameters
-        message_send(
+        response = message_send(
             "Approval Result",
-            {"payload": {"po_number": 1001, "customer_id": "Sartography"}},
+            {"po_number": 1001, "customer_id": "Sartography"},
         )
 
+        # The response's task data should also match up with the correlation keys.
+        response_json = response.json
+        assert response_json["task_data"]["po_number"] == 1001
+        assert response_json["task_data"]["customer_id"] == "Sartography"
+
         # There is no longer a waiting message
         waiting_messages = (
             MessageInstanceModel.query.filter_by(message_type="receive")

spiffworkflow-backend/tests/spiffworkflow_backend/integration/test_process_api.py

@@ -550,7 +550,7 @@ class TestProcessApi(BaseTest):
             bpmn_file_name="simple_form",
         )
         # When adding a process model with one Process, no decisions, and some json files, only one process is recorded.
-        assert len(ReferenceCacheModel.basic_query().all()) == 1
+        assert ReferenceCacheModel.basic_query().count() == 1
 
         self.create_group_and_model_with_bpmn(
             client=client,
@@ -560,7 +560,7 @@ class TestProcessApi(BaseTest):
             bpmn_file_location="call_activity_nested",
         )
         # When adding a process model with 4 processes and a decision, 5 new records will be in the Cache
-        assert len(ReferenceCacheModel.basic_query().all()) == 6
+        assert ReferenceCacheModel.basic_query().count() == 6
 
         # get the results
         response = client.get(
@@ -592,7 +592,7 @@ class TestProcessApi(BaseTest):
             bpmn_file_name="simple_form",
         )
         # When adding a process model with one Process, no decisions, and some json files, only one process is recorded.
-        assert len(ReferenceCacheModel.basic_query().all()) == 1
+        assert ReferenceCacheModel.basic_query().count() == 1
 
         self.create_group_and_model_with_bpmn(
             client=client,
@@ -602,7 +602,7 @@ class TestProcessApi(BaseTest):
             bpmn_file_location="call_activity_nested",
         )
         # When adding a process model with 4 processes and a decision, 5 new records will be in the Cache
-        assert len(ReferenceCacheModel.basic_query().all()) == 6
+        assert ReferenceCacheModel.basic_query().count() == 6
 
         user_one = self.create_user_with_permission(username="user_one", target_uri="/v1.0/process-groups/test_group_one:*")
         self.add_permissions_to_user(user=user_one, target_uri="/v1.0/processes", permission_names=["read"])
@@ -642,7 +642,7 @@ class TestProcessApi(BaseTest):
             bpmn_file_name="simple_form",
         )
         # When adding a process model with one Process, no decisions, and some json files, only one process is recorded.
-        assert len(ReferenceCacheModel.basic_query().all()) == 1
+        assert ReferenceCacheModel.basic_query().count() == 1
         # but no callers are recorded
         assert ProcessCallerService.count() == 0
 
@@ -654,7 +654,7 @@ class TestProcessApi(BaseTest):
             bpmn_file_location="call_activity_nested",
         )
         # When adding a process model with 4 processes and a decision, 5 new records will be in the Cache
-        assert len(ReferenceCacheModel.basic_query().all()) == 6
+        assert ReferenceCacheModel.basic_query().count() == 6
         # and 4 callers recorded
         assert ProcessCallerService.count() == 4
 
@@ -1462,13 +1462,14 @@ class TestProcessApi(BaseTest):
             f"/v1.0/messages/{message_model_identifier}",
             content_type="application/json",
             headers=self.logged_in_headers(with_super_admin_user),
-            data=json.dumps({"payload": payload}),
+            data=json.dumps(payload),
         )
         assert response.status_code == 200
         json_data = response.json
         assert json_data
-        assert json_data["status"] == "complete"
-        process_instance_id = json_data["id"]
+        assert json_data["process_instance"]["status"] == "complete"
+        assert json_data["task_data"]["invoice"] == payload
+        process_instance_id = json_data["process_instance"]["id"]
         process_instance = ProcessInstanceModel.query.filter_by(id=process_instance_id).first()
         assert process_instance
 
@@ -1537,13 +1538,14 @@ class TestProcessApi(BaseTest):
             f"/v1.0/messages/{message_model_identifier}",
             content_type="application/json",
             headers=self.logged_in_headers(with_super_admin_user),
-            data=json.dumps({"payload": payload, "process_instance_id": process_instance_id}),
+            data=json.dumps(payload),
         )
         assert response.status_code == 200
         json_data = response.json
         assert json_data
-        assert json_data["status"] == "complete"
-        process_instance_id = json_data["id"]
+        assert json_data["process_instance"]["status"] == "complete"
+        assert json_data["task_data"]["the_payload"] == payload
+        process_instance_id = json_data["process_instance"]["id"]
         process_instance = ProcessInstanceModel.query.filter_by(id=process_instance_id).first()
         assert process_instance
 
@@ -1609,7 +1611,7 @@ class TestProcessApi(BaseTest):
             f"/v1.0/messages/{message_model_identifier}",
             content_type="application/json",
             headers=self.logged_in_headers(with_super_admin_user),
-            data=json.dumps({"payload": payload, "process_instance_id": process_instance_id}),
+            data=json.dumps(payload),
         )
         assert response.status_code == 400
         assert response.json
@@ -1621,13 +1623,13 @@ class TestProcessApi(BaseTest):
             f"/v1.0/messages/{message_model_identifier}",
             content_type="application/json",
             headers=self.logged_in_headers(with_super_admin_user),
-            data=json.dumps({"payload": payload}),
+            data=json.dumps(payload),
         )
         assert response.status_code == 200
         json_data = response.json
         assert json_data
-        assert json_data["status"] == "complete"
-        process_instance_id = json_data["id"]
+        assert json_data["process_instance"]["status"] == "complete"
+        process_instance_id = json_data["process_instance"]["id"]
         process_instance = ProcessInstanceModel.query.filter_by(id=process_instance_id).first()
         assert process_instance
         processor = ProcessInstanceProcessor(process_instance)
@@ -1640,7 +1642,7 @@ class TestProcessApi(BaseTest):
             f"/v1.0/messages/{message_model_identifier}",
             content_type="application/json",
             headers=self.logged_in_headers(with_super_admin_user),
-            data=json.dumps({"payload": payload, "process_instance_id": process_instance_id}),
+            data=json.dumps(payload),
         )
         assert response.status_code == 400
         assert response.json
@@ -2282,22 +2284,22 @@ class TestProcessApi(BaseTest):
             f"/v1.0/messages/{message_model_identifier}",
             content_type="application/json",
             headers=self.logged_in_headers(with_super_admin_user),
-            data=json.dumps({"payload": payload}),
+            data=json.dumps(payload),
         )
         assert response.status_code == 200
         assert response.json is not None
-        process_instance_id_one = response.json["id"]
+        process_instance_id_one = response.json["process_instance"]["id"]
 
         payload["po_number"] = "1002"
         response = client.post(
             f"/v1.0/messages/{message_model_identifier}",
             content_type="application/json",
             headers=self.logged_in_headers(with_super_admin_user),
-            data=json.dumps({"payload": payload}),
+            data=json.dumps(payload),
         )
         assert response.status_code == 200
         assert response.json is not None
-        process_instance_id_two = response.json["id"]
+        process_instance_id_two = response.json["process_instance"]["id"]
 
         response = client.get(
             f"/v1.0/messages?process_instance_id={process_instance_id_one}",