A packet handler, as the name suggests, handles a packet with a specific header from the client to the server.
A source contains a large number of packet handlers as they are responsible for the role of the server of interacting with the game clients, each responding to a particular action of the player with triggered the packet to be sent by the game client.
A packet handler may
- alter the database
- send another packet back to the player
- send multiple packets to other players
depending on the action of the player.