Transferring Data on an LU-LU Session

After the LU-LU session is established and the SLU program responds to the SDT command, data transfer can begin. For a data transmission operation, a message moves from end-user storage to Personal Communications or Communications Server storage until it is transmitted. For a data-reception operation, either program would place a message in its own storage and then move the message into end-user storage.

Quiesce protocols suspend the transfer of data in an LU-LU session. The PLU or the SLU can send the following Quiesce protocol commands:
  • Quiesce at End of Chain (QEC). This command requests that the receiver of this command stop sending data after sending the last part in a data chain. A data chain is a series of related messages. For more information about data chaining, see Using the Data-Chaining Protocol.
  • Quiesce Complete (QC). This command notifies a QEC command that data transfer is suspended. When the SLU sends the QC command, either Personal Communications or Communications Server prevents the SLU from sending any normal-flow messages until the Release Quiesce (RELQ) command is received.
  • Release Quiesce (RELQ). This command notifies the receiver that data can again be transferred.