Hello everyone!
We just published a new version of Socket.IO: 3.1.0
In order to ease the migration to Socket.IO v3, the v3 server is now able to communicate with v2 clients:
const io =require("socket.io")({
allowEIO3:true// false by default
});
This should make the migration easier for existing deployments:
- first, update the servers with
allowEIO3set totrue
const io =require("socket.io")({
allowEIO3:true// false by default
});
Note: If you are using the Redis adapter to broadcast packets between nodes, you must use socket.io-redis@5 with socket.io@2 and socket.io-redis@6 with socket.io@3. Please note that both versions are compatible, so you can update each server one by one (no big bang is needed).
- then, update the clients
This step may actually take some time, as some clients may still have a v2 client in cache.
You can check the version of the connection with:
io.on("connection",(socket)=>{
const version = socket.conn.protocol;// either 3 or 4
});
This matches the value of the EIO query parameter in the HTTP requests.
- and finally, once every client was updated, set
allowEIO3tofalse(which is the default value)
const io =require("socket.io")({
allowEIO3:false
});
With allowEIO3 set to false, v2 clients will now receive an HTTP 400 error (Unsupported protocol version) when connecting.
The migration guide was updated accordingly.
Features
- confirm a weak but matching ETag (#3485) (161091d)
- esm: export the Namespace and Socket class (#3699) (233650c)
- add support for Socket.IO v2 clients (9925746)
- add room events (155fa63)