Effectively-Once support for WebSockets

[cvuijst]

Is your feature request related to a problem? Please describe.
On the Pulsar client feature matrix, the "Effectively-Once" feature is not available for the WebSocket client. The matrix seems currently updated till Pulsar 2.5.0, see here. Is there any chance this will be supported in the future? Or does anyone have experience how to make this happen in a different way?

Describe the solution you'd like
Solution preferred to be embedded through the Pulsar WebSocket server.

Describe alternatives you've considered
Alternatives might be:

• Enhance the messages send and acknowledges received to impose effectively once tracking at the client side.
• Enhance documentation how this can be achieved in another way outside the Pulsar scope. For example, an end to end scenario that proves effectively once based on WebSocket integration.

Additional context
This issue is created as follow up on the Pulsar Slack Channel # general, message: https://apache-pulsar.slack.com/archives/C5Z4T36F7/p1601446017085700

[BewareMyPower]

The WebSocket already supports effectively-once because the client side only needs to set producer name and timeout, i.e. sendTimeoutMillis and producerName. See http://pulsar.apache.org/docs/en/client-libraries-websocket/#producer-endpoint for details.

The effectively-once means message deduplication from producer side, see http://pulsar.apache.org/docs/en/cookbooks-deduplication/#pulsar-clients

And the equivalent Python code through WebSocket is:

import websocket

url = 'ws://localhost:8080/ws/v2/producer/persistent/public/default/topic-1?producerName=producer-1&sendTimeoutMillis=0'
ws = websocket.create_connection(url)

It should be supported a long time ago but the client feature matrix in wiki was wrong.

[cvuijst]

Sounds like a solution, thank you for the additional description.