writeMessage writes a message with the given message type and payload.

newPgListener creates and returns the pglistener from the pq package.

the reader listens for incoming messages on the websocket. the purpose is that the client sends a string message containing the tablename it wants to

writeMessage marshals an interface to json and sends it.

writer writes the pgnotificiations it receives from the hub to the websocket connection.

Listen makes the PgBroadcaster's underlying pglistener listen to thh specified channel

serverWs handles websocket requests from the peer.