HP-UX SNAplus2 R7 APPC Programmer's Guide

Writing Transaction Programs

APPC Verb Summary

The ALLOCATE verb can establish either a basic or mapped conversation. The MC_ALLOCATE verb can

start only a mapped conversation. Either verb can start either a full-duplex or a half-duplex conversation.

Once the conversation is allocated, APPC returns a conversation identiﬁer (

conv_id) through this verb.

MC_SEND_CONVERSATION or SEND_CONVERSATION

This verb is issued by the invoking TP. It allocates a session between the local LU and a remote LU, establishes

a conversation between the invoking TP and the invoked TP, sends a single data record on this conversation,

and deallocates the conversation.

RECEIVE_ALLOCATE

This verb is issued by the invoked TP. It conﬁrms that the invoked TP is ready to begin a conversation with the

invoking TP, which issued the [MC_]ALLOCATE verb. Upon successful execution, RECEIVE_ALLOCATE

returns a TP identiﬁer (tp_id) for the invoked TP and the conversation identiﬁer (conv_id).

2.2.2 Sending Data

The following verbs send data to the partner TP:

MC_SEND_DATA or SEND_DATA

This verb puts data in the local LU’s send buffer for transmission to the partner TP.

The data collected in the local LU’s send buffer is transmitted to the partner LU (and partner TP) when one

of the following occurs:

• The send buffer ﬁlls up.

• The local TP issues a verb that ﬂushes the local LU’s send buffer, such as [MC_]FLUSH or

[MC_]CONFIRM. ([MC_]CONFIRM applies to half-duplex conversations only.)

The [MC_]SEND_DATA verb can also perform the function of the [MC_]CONFIRM,

[MC_]DEALLOCATE, [MC_]FLUSH, or [MC_]PREPARE_TO_RECEIVE verbs. ([MC_]CONFIRM and

[MC_]PREPARE_TO_RECEIVE apply to half-duplex conversations only.)

MC_SEND_EXPEDITED_DATA or SEND_EXPEDITED_DATA

This verb puts data in the local LU’s expedited send buffer for transmission to the partner TP.

The data collected in the local LU’s send buffer is transmitted to the partner LU (and partner TP) in the same

way as for the [MC_]SEND_DATA verb. However, because the data is sent over the network as expedited

data, it may arrive before data that was sent earlier using [MC_]SEND_DATA.

MC_FLUSH or FLUSH

This verb ﬂushes the local LU’s send buffer, sending the contents of the buffer to the partner LU (and TP).

If the send buffer is empty, no action occurs.

MC_CONFIRM or CONFIRM (half-duplex conversation only)

This verb sends both the contents of the local LU’s send buffer and a conﬁrmation request to the partner TP.

MC_PREPARE_TO_RECEIVE or PREPARE_TO_RECEIVE (half-duplex conversation only)

This verb changes the state of the conversation from Send to Receive. Before changing the conversation

state, this verb performs the equivalent of the [MC_]FLUSH or [MC_]CONFIRM verb. After this verb has

successfully executed, the TP can receive data.

MC_REQUEST_TO_SEND or REQUEST_TO_SEND (half-duplex conversation only)

This verb informs the partner TP that the local TP wants to send data. If the partner TP issues the

[MC_]PREPARE_TO_RECEIVE or [MC_]RECEIVE_AND_WAIT verb, the conversation state changes to

Receive for the partner TP, which makes it possible for the local TP to begin to send data.