After registering a lobby-aware application and adding the code to support external lobby launching, the next step in integrating the application with the lobby is to send information back to the lobby or request information from the lobby. This is done by exchanging messages with the lobby through the IDirectPlayLobby2::SendLobbyMessage and IDirectPlayLobby2::ReceiveLobbyMessage methods on the IDirectPlayLobby2 interface. Standard message structures have been defined by DirectPlay to facilitate this functionality.
Sending information to the lobby is done through setting properties. The application must create and fill in a DPLMSG_SETPROPERTY structure and send it to the lobby by using the SendLobbyMessage method. Each property identifies a distinct type of data. The application developer should generate GUIDs (using Guidgen.exe) for every property that will be set. The lobby operator needs to obtain this list of GUIDs from the application developer along with the description of each property and the data structure of the property.
Properties can take the form of:
·Current individual player scores.
·Final individual player scores.
·Player configuration for later retrieval.
·Current game status (level or mission).
The lobby can store this information or display it to other users in the lobby so they can monitor the game's progress. An application can request confirmation that the property was set correctly by supplying a nonzero request ID with the set property message.
Requesting information from the lobby is done through requesting properties. The application must create and fill in a DPLMSG_GETPROPERTY structure and send it to the lobby by using the SendLobbyMessage method. At some later time, the lobby will send a message back to the application - a DPLMSG_GETPROPERTYRESPONSE structure that contains the property data that was requested. The application can retrieve the message from the lobby message queue using the ReceiveLobbyMessage method. As before, the application developer generates the GUIDs for each property and the lobby operator must obtain them from the developer.
The following list shows examples of some properties that can be requested from the lobby:
·Game configuration settings - enables players to configure the game in the lobby before launching the game.
·Player configuration settings - enables players to configure their players in the lobby or use a stored configuration from a previous session.
·Other information stored from a previous session.
Not all lobbies will be able to support these standard lobby messages. The application can determine if the lobby that it was launched from supports standard lobby messages by sending a DPLMSG_GETPROPERTY message requesting the DPLPROPERTY_MessagesSupported property.