Issues with README Examples and WebSocket Compatibility

[AlessandroAmadoriTNO]

Hello everyone,

I encountered several issues while trying to install and reproduce the examples provided in the README and the scripts in the example folder. Here are the details:

1. Variable Naming Inconsistency:

   • In the README, the variables RegistrationStatusType should be renamed to RegistrationStatusEnumType for both csms and cp.

2. WebSocket Compatibility Issues:

   • The README recommends installing a generic version of websockets, which is at the moment version 14. However, this version introduces breaking changes compared to version 13, resulting in the following errors:

     • For cp:

       websockets.exceptions.ConnectionClosedError: received 1011 (internal error); then sent 1011 (internal error)
       INFO:websockets.server:server listening on 0.0.0.0:9000
       INFO:root:WebSocket Server Started
       INFO:websockets.server:connection open
       ERROR:websockets.server:connection handler failed
       TypeError: on_connect() missing 1 required positional argument: 'path'
       

     • For csms:

       INFO:websockets.server:server listening on 0.0.0.0:9000
       INFO:root:WebSocket Server Started
       INFO:websockets.server:connection open
       INFO:root:Protocols Matched: ocpp2.0.1
       INFO:ocpp:CP_1: receive message [2,"0b2c05c7-6945-4327-8003-4f6ae9c7ce7c","BootNotification",{"chargingStation":{"model":"Wallbox XYZ","vendorName":"anewone"},"reason":"PowerUp"}]
       INFO:root:Received BootNotification: {'model': 'Wallbox XYZ', 'vendor_name': 'anewone'}, PowerUp
       ERROR:ocpp:Error while handling request '<Call - unique_id=0b2c05c7-6945-4327-8003-4f6ae9c7ce7c, action=BootNotification, payload={'chargingStation': {'model': 'Wallbox XYZ', 'vendorName': 'anewone'}, 'reason': 'PowerUp'}>'
       websockets.exceptions.ConnectionClosedOK: received 1000 (OK); then sent 1000 (OK)
       INFO:websockets.server:connection closed
       

   • Downgrading to version 13.1 of websockets resolves some issues, but I still encounter the following errors:

     • For /examples/v201/central_system.py :

       INFO:websockets.server:server listening on 0.0.0.0:9000
       INFO:root:WebSocket Server Started
       INFO:websockets.server:connection open
       INFO:root:Protocols Matched: ocpp2.0.1
       INFO:ocpp:CP_1: receive message [2,"0b2c05c7-6945-4327-8003-4f6ae9c7ce7c","BootNotification",{"chargingStation":{"model":"Wallbox XYZ","vendorName":"anewone"},"reason":"PowerUp"}]
       INFO:root:Received BootNotification: {'model': 'Wallbox XYZ', 'vendor_name': 'anewone'}, PowerUp
       ERROR:ocpp:Error while handling request '<Call - unique_id=0b2c05c7-6945-4327-8003-4f6ae9c7ce7c, action=BootNotification, payload={'chargingStation': {'model': 'Wallbox XYZ', 'vendorName': 'anewone'}, 'reason': 'PowerUp'}>'
       websockets.exceptions.ConnectionClosedOK: received 1000 (OK); then sent 1000 (OK)
       INFO:websockets.server:connection closed
       

     • For /examples/v201/charge_point:

       AttributeError: module 'ocpp.v201.call' has no attribute 'BootNotificationPayload'. Did you mean: 'BootNotification'?
       

   • Similarly, for csms:

    INFO:websockets.server:server listening on 0.0.0.0:9000
    INFO:root:WebSocket Server Started
    INFO:websockets.server:connection open
    INFO:root:Protocols Matched: ocpp2.0.1
    INFO:ocpp:CP_1: receive message [2,"0b2c05c7-6945-4327-8003-4f6ae9c7ce7c","BootNotification",{"chargingStation":{"model":"Wallbox XYZ","vendorName":"anewone"},"reason":"PowerUp"}]
    INFO:root:Received BootNotification: {'model': 'Wallbox XYZ', 'vendor_name': 'anewone'}, PowerUp
    ERROR:ocpp:Error while handling request '<Call - unique_id=0b2c05c7-6945-4327-8003-4f6ae9c7ce7c, action=BootNotification, payload={'chargingStation': {'model': 'Wallbox XYZ', 'vendorName': 'anewone'}, 'reason': 'PowerUp'}>'
    websockets.exceptions.ConnectionClosedOK: received 1000 (OK); then sent 1000 (OK)
    INFO:websockets.server:connection closed
   

   • for cp:

   INFO:ocpp:CP_1: receive message [4,"0b2c05c7-6945-4327-8003-4f6ae9c7ce7c","InternalError","An unexpected error occurred.",{}]
   WARNING:ocpp:Received a CALLError: <CallError - unique_id=0b2c05c7-6945-4327-8003-4f6ae9c7ce7c, error_code=InternalError, error_description=An unexpected error occurred., error_details={}>'
   

3. Working Commit:

   • All examples work correctly if I checkout the commit d25580c9a66c68843d49ebe8dbec24056654e27c.

Questions:

1. Is it possible to update the examples in the README to reflect the correct variable names and ensure compatibility with the latest release?
2. Can we have running examples for the latest release?
3. Are there any plans to add support for websockets version 14?

[a-alak]

1. Agree, the README could really use an upgrade, and the current maintainers have an open issue on this was well: Improve documentation #702. I have it on my to do, to suggest something, but I just haven't found time to it yet.

2. As I can see "websockets" library is not a dependency, but this library expects some behavior from the websocket connection. The only expected behaviour is asynchronous .send() and .recv() methods, and those have not been changed in websockets v14. So this library supports v14. However of course the examples given in README is not compatible with v14.

As of the issues you are having I can only identify the first issue as due to incompatibility with websockets v14. You can find a solution for that here #708.

The second issue you have is actually due to the example in README not being compatible with v2 of this library. The "Payload"-suffix is deprecated and you should just delete that. BootNotificationPayload is now just called BootNotification.

The third issue I can't really identify the problems from the added logs, could you maybe show the code?

[a-alak]

Also I think the websocket compatibility is maybe an interesting topic to discuss. It could be to enable different websocket interfaces. Some of the webframeworks that support websockets use .recieve() instead of .recv() and maybe I saw somewhere .call() instead of .send().

I don't have good suggestion on how to make this library compatible with all different websocket implementations, but might be interesting to look in to.

[AlessandroAmadoriTNO]

Hello Ali,

Thank you for your reply,

On point 3 I have not written any code, the only thing I did was:

1. clone the repository,
2. checkout commit d25580c,
3. $ pip install .
4. run the python scripts in the example folder

The reason I checkout that commit was simply because it was the last one involving the scripts in /examples/v201 .

On the websocket, I was actually trying to see if I could run OCPP with some websockets with specific SSL contexts which have their special requirements (which we are starting to develop) and use the provided examples as starting point, but unfortunately they were not working out of the box with the latest release. I'll checkout if issue #708 can help.
Also, I wanted to understand if we needed to start working with websockets version 14 or 13 due to the fact that I could make the examples work for v13.

[a-alak]

I created the updates to the examples code that makes it compatible with websockets v14 and ocpp v2 in this PR #710. I think you can safely work with websockets version 14.

[AlessandroAmadoriTNO]

Works like a charm! Thank you for your assistance