sequence diagram for database listener interface (#35)

README.md

@@ -367,6 +367,9 @@ This data is also reported to the console at the end of each test.
 ## Time Series DB Reporting and Tagging
 <a id="db-reporting"></a>
 
+Additional design details about how a database listener works with grasshopper/locust can be 
+found in the [Database Listener Design Documentation](./docs/database_listener_design_documentation.md).
+
 When you specify a time series database URL param to `launch_test`, such as 
 `influx_host`, all metrics will be automatically reported to tables within the `locust` 
 timeseries database via the specified URL. These tables include:

docs/database_listener_design_documentation.md

@@ -0,0 +1,5 @@
+# Database Listener for Locust/Grasshopper Design Documentation
+
+## Sequence Diagram of how listeners are currently working within the framework
+
+![Sequence Diagram](database_listeners_sequence_diagram.svg)

docs/database_listeners_sequence_diagram.puml

@@ -0,0 +1,48 @@
+# Grasshopper (Locust) Database Listeners
+
+@startuml
+actor GrasshopperTest
+box "Grasshopper" #LightBlue
+boundary LaunchTest
+entity Grasshopper
+entity GrasshopperListeners
+end box
+entity LocustDBListener
+boundary DbClient
+database Database
+boundary Locust
+
+GrasshopperTest -> LaunchTest : run test
+activate LaunchTest
+
+LaunchTest -> Grasshopper : create new grasshopper object
+activate Grasshopper
+Grasshopper --> LaunchTest : grasshopper object
+
+LaunchTest -> GrasshopperListeners : create new listeners object
+activate GrasshopperListeners
+
+GrasshopperListeners -> LocustDBListener : create new listener object
+activate LocustDBListener
+LocustDBListener -> DbClient : create new client object
+activate DbClient
+DbClient -> Database : connect
+DbClient --> LocustDBListener : new client object
+deactivate DbClient
+LocustDBListener ->> Locust : register listeners on locust events
+LocustDBListener --> GrasshopperListeners : new listener object
+deactivate LocustDBListener
+
+GrasshopperListeners --> LaunchTest : new listeners object
+deactivate GrasshopperListeners
+
+
+deactivate Grasshopper
+deactivate LaunchTest
+
+GrasshopperTest -> Locust : send http request (via API library, wich calls the Locust request method)
+Locust ->> LocustDBListener : call listener on request event
+LocustDBListener ->> DbClient : add metric for the request
+DbClient ->> Database : post data point
+
+@enduml