LU 6.2 API Application Programmer's Reference Guide (30294-90008)

Chapter 3 43

Using Intrinsics

Two-Way Conversation Without Conﬁrm

In order to carry on a two-way conversation, a TP must be able to

inform its partner that it is ﬁnished sending data and is ready to

receive. It also must wait for data sent by its partner and receive the

data when it arrives. The two-way conversation illustrated in Figure

3-6 uses the MCPrepToRcv and MCRcvAndWait intrinsics as well as the

intrinsics already introduced.

MCPrepToRcv

The local TP uses the MCPrepToRcv intrinsic to relinquish control of the

conversation and give the remote TP permission to send data. It

replaces “person relinquishes control of conversation.”

MCRcvAndWait

The MCRcvAndWait intrinsic waits for data from the remote TP and

receives data when it arrives. The

WhatReceived

parameter of the

MCRcvAndWait intrinsic tells the local TP what it has received: control

information or data. A TP cannot receive both control information and

data in the same call to MCRcvAndWait; it must issue a separate call to

MCRcvAndWait for each one.

The two calls to MCRcvAndWait in Figure 3-6 perform different

functions: The ﬁrst call receives the data being sent, and the second call

receives notiﬁcation that the remote TP is ready to receive data.