Supported Logical Unit Types (About Communication Adapters)

About Communication Adapters

Supported Logical Unit Types

SNA LU6.2

LU 6.2, also known as APPC (Advanced Program-to-Program Communication), is used for Transaction Programs communicating with each other in a distributed data processing environment. In a CPIC (Common Programming Interface for Communications) implementation, CPIC provides the API that contains the commands, known as verbs, that are used by LU 6.2 to establish communication sessions.

Two types of Presentation Service interfaces are possible with LU6.2: mapped conversations and unmapped, or basic, conversations. The following table summarizes the set of LU6.2 commands for basic conversations. Equivalent commands for mapped conversations have the prefix <MC_> added to the command name. Note that “control operator verbs” are not listed.

Table 1 LU6.2 Commands


Name	Description
ALLOCATE	Allocates a conversation with another program.
CONFIRM	Sends a confirmation request to the remote process and waits for a reply.
CONFIRMED	Sends a confirmation reply to the remote process.
DEALLOCATE	De-allocates a conversation.
FLUSH	Forces the transmission of the local SEND buffer to the other LU.
GET_ATTRIBUTES	Obtains information about a conversation.
PREPARE_TO_RECEIVE	Changes the conversation state from SEND to RECEIVE.
RECEIVE_AND_WAIT	Waits for information (either data or confirmation request) to be received from the partner process.
RECEIVE_IMMEDIATE	Receives any information that is available in the local LU’s buffer, but does not wait for information to arrive.
REQUEST_TO_SEND	Notifies the partner process that the local process wants to send data. When a “send” indication is received from the partner process, the conversation state changes.
SEND_DATA	Sends one data record to the partner process.
SEND_ERROR	Informs the partner process that the local process has detected an application error.