Any servers that handles mutliple connections must

• Wait to read incomming connections from the server socket.
• Wait to read incomming requests from each client socket from which a request hasn't been obtained.
• Wait to write reponses to each client socket from which a request has been obtained.
• Wait for errors.

All of these can occur at the same time, which is why can_* are insufficient, and select is desired on the server side.

Any clients that handles mutliple connections must

• Wait to write requests to every server socket to which a request has not been sent.
• Wait to read incomming responses from each server socket to which a request has been sent.
• Wait for errors.

All of these can occur at the same time, which is why can_* are insufficient, and select is desired on the client side.