Message Boundary

Preserving the boundaries of the messages is another feature that TCPMPL has to provide for WARPED. The application processes communicate with other processes in the form of messages. Therefore, when a process sends a message of size bytes followed by a message of size bytes, the message passing layer should give the first bytes as a unique message to the destination process followed by a message of size bytes. It should preserve the message boundary. TCPMPL uses the standard approach used in networking applications. It has its own protocol and communicates messages according to it. Every message sent by a process is prepended by a message header which has information about the message that follows. The message header is of fixed size. Therefore, the message passing layer can be ensured that if data comes from a communication channel, it is going to be the message header first followed by the data. The typical contents of the message header are as follows:

• sender process identity,
• destination process identity, and
• size of the message that follows the message header.