Whiteboard uses RPCs (Remote Procedure Calls) for communication between client end server. Two clients cannot communicate, they must use the server. For sending data from the client to the server the TCP/IP-protocol is used for save and reliable transmission of data of any length. As to save network bandwidth, the communication from the server to the client is handled differently. Those messages are sent by the UDP/IP-protocol as broadcasts.
This brings you some disadvantages, as you can only send about 900 Bytes of data per RPC over UDP/IP because of the packet length. This means, you have to do splitting of larger messages and controlling, wether all of the message parts arrived or not. This means, what you get for free with TCP/IP you have to do manually by UDP/IP.
In future versions it is planned to replace the UDP/IP-Broadcasts by Multicasts over Socket-Calls. This means yet more mixing of technologies (RPC - Socket calls), but it would be an extension into future technologies with an appropriate example.
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Last change: 15 Dezember 1997 (c) 1997 Michael V. Sonntag |