User guide

174 DC 900-1338I
Protocol Software Toolkit Programmer Guide
9.2.7 Writing to an ICP Link
After the application has issued a bind command to the ICP, it can send messages to the
ICP for transmission to the wide-area network. When the ICP receives a message from
the client for transmission, it prepares it as required and sends it on the specified link.
When the last character is transmitted, the ICP sends a message to the application. The
message written by the ICP to the client is called an acknowledgment, however, in this
case “acknowledgment” means that the client’s message has been transmitted and the
memory buffer containing the message has been freed for reuse. It does not mean that
the opposite end of the network has acknowledged that it correctly received the mes-
sage. This is an important area of wide-area communications. It is vital to determine
which system is responsible for maintaining a message in case the ultimate end reader
does not receive it and the message must be retransmitted. The ICP does not have a
disk, and may not be the best platform for maintaining an extensive queue of messages.