help request: How to Detect WebSocket Connection Closure in Java Plugin Development for APISIX?

[dinghuang]

Description

Hello APISIX Team,

I am currently developing a custom Java plugin for APISIX and would like to implement functionality similar to the limit-conn plugin. However, I have encountered an issue regarding WebSocket connections.

In my plugin, I need to maintain a count of active WebSocket connections and decrement the count when a connection is closed. Unfortunately, the provided SDK does not seem to expose a callback or event mechanism to detect when a WebSocket connection is closed. This makes it challenging for me to accurately manage the connection count.

Could you please provide guidance on how to handle this scenario? Specifically, I would like to know:

Is there any way to detect WebSocket connection closures within a Java plugin?
If no direct callback is available, are there alternative approaches or workarounds to achieve this functionality (e.g., leveraging Nginx's internal mechanisms or other APIs)?
Any advice or examples would be greatly appreciated. Thank you for your time and support!

Environment

• APISIX version (run apisix version):
• Operating system (run uname -a):
• OpenResty / Nginx version (run openresty -V or nginx -V):
• etcd version, if relevant (run curl http://127.0.0.1:9090/v1/server_info):
• APISIX Dashboard version, if relevant:
• Plugin runner version, for issues related to plugin runners:
• LuaRocks version, for installation issues (run luarocks --version):

[juzhiyuan]

Hi @dinghuang, just curious why you want to re-implement the rate limit feature in Java?

May off the topic but I suggest using Lua to achieve your custom plugins.

[dinghuang]

Hello, I will try your suggestion. The reason I want to write my own plugin is that I have a user service that maintains user information in Redis, including package information. I don't want to use the consumer group feature of APISIX because maintaining data consistency between the user service and the consumer group would incur development costs. Therefore, I plan to write my own rate-limiting functionality.