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Version: 2022-05__Heidelbeere


nodejs for messages

The chats have a separate way of communication between client and server. For all other pages the initiative starts at the client, the client sends a request to the (php) server and gets an answer. Each request uses one connection that is closed afterwards. This is not useful for the chats since the server knows that there are new messages and has to tell the client.

For this case there exists a separate nodejs server (on the same machine as the php server but separate). This holds an open connection to each user that has open on their device. Each time a message arrives at the php server, it sends this information to the nodejs server via a websocket

which uses the connection to the client to send the message. Note that there can be several connections to each session, of which there can be several for each user. nodejs sends the message to all connections of all addressed users.

The code for the nodejs server is found in /chat/src/index.ts and other files in /chat/src chat/ -> nodejs server, in chat/src/index.ts. There is documentation for all used parts in /chat/node_modules/<modulename>/ All nodejs-documentation is found on their webpage.

  • php server tells websocket that there is a new message
  • nodejs-server sends message to all open connections of all sessions of all users