Add more commentary to WorkflowService about what needs to be implemented

shared/workspaces/src/workspaces/services.py

@@ -17,19 +17,22 @@ class WorkflowService(WorkflowServiceIF):
             # 1. look up the workflow info for this workflow name
             info = self.db.lookup_workflow_definition(workflow_name)
 
-            # 2. render the templates to files
+            # 2. create and save this request to the database
+            record = WorkflowRequest(...)
+
+            # 3. render the templates to files
             contents = info.render_templates(argument, files)
 
-            # 3. serialize the templated files
+            # 4. serialize the templated files
             temp_folder = self._prepare_files_for_condor(contents)
 
-            # 4. execute condor and get the log file
+            # 5. execute condor and get the log file
             log_file = self._execute_prepared(temp_folder)
 
-            # 5. start reading the logs
+            # 6. start reading the logs
             return HTCondorWorkflowEventStream(log_file)
 
-        Of these, step 5 is going to have to be the most different, because
+        Of these, step 6 is going to have to be the most different, because
         that's launching the new CLI wf_monitor program that Nathan wrote.
         The other steps are more similar than different, though figuring out
         where to put the temp files will be interesting.
@@ -81,6 +84,45 @@ class WorkflowService(WorkflowServiceIF):
         # return the logfile
         return logfile
 
+    # The next few things that need to happen here are in response to
+    # WorkflowEvents that we receive from wf_monitor as the workflow
+    # execution evolves. So we have to set up listening at some point
+    # in this class
+    def __init__(self):
+        # 1. Start listening for events from the wf_monitor stream
+        # self.channel = channels.workflow_events.listen(self.on_workflow_event)
+        raise NotImplementedError
+
+    def on_workflow_event(self, event: WorkflowEvent):
+        # 1. log that we received this event, somehow
+        # 2. update the WorkflowRequest record with the state we got
+        # 3. do per-event-type stuff, such as level change events, database
+        #    updates, and logging
+        if event.type == WorkflowEventType.SUBMITTED:
+            # this would be a good place to emit a level-changed event
+            # for the capability system, such as:
+            #
+            #   channels.capability_events.send(...)
+            #
+            # however, for now we can pass
+            pass
+        elif event.type == WorkflowEventType.EXECUTING:
+            # another good place to emit a level-changed event
+            pass
+        elif event.type == WorkflowEventType.TERMINATED:
+            # another level-change event opportunity
+            # also, we must now locate the temporary directory and
+            # remove it
+            pass
+        # there is an event type of OTHER which we can basically
+        # ignore for now
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        # this method lets us use "with WorkflowService as ws" type syntax
+        # we should close our AMQP channel gracefully here
+        # self.channel.close()
+        pass
+
 
 class WorkflowInfo(WorkflowInfoIF):
     """