A

A3270

The server transaction program for the APPC 3270 Terminal Emulator facility.

ACTLU

SNA command sent by the SSCP to an LU to activate a session and establish session parameters.

ACTPU

SNA command sent by the SSCP to activate a PU, so that any logical units controlled by this PU are available to the SNA network.

Advanced Peer-To-Peer Networking (APPN)

An extension to SNA that features (a) greater distributed network control that avoids critical hierarchical dependencies, thereby isolating the effects of single points of failure; (b) dynamic exchange of network topology information to foster ease of connection, reconfiguration, and adaptive route selection; (c) dynamic definition of network resources; and (d) automated resource registration and directory lookup. APPN extends the LU 6.2 peer orientation for end-user services to network control and supports multiple LU types, including LU 2, LU 3, and LU 6.2.

Advanced Program-to-Program Communication (APPC)

(1) The general term that characterizes the LU 6.2 architecture and its various implementations in products. (2) Sometimes used to refer to the LU 6.2 architecture and its product implementations as a whole, or to an LU 6.2 product feature in particular, such as an APPC application programming interface. (3) A method for allowing programs to communicate directly with each other across a network or within a single system. APPC uses a type of LU called LU 6.2, and allows TPs to engage in peer-to-peer communications in an SNA environment.

AFTP

(1) APPC File Transfer Protocol. (2) The client transaction program for the APPC File Transfer Protocol facility. (3) An interactive full-screen environment with a specific set of commands used to manage and transfer files between a client and server computer. (4) An API that provides APPC file transfer capabilities.

AFTPD

The server transaction program for the APPC File Transfer Protocol facility.

alert

A message sent to indicate an abnormal event or a failure.

allocate

(1) The process an operating system uses to respond to a request from a program to reserve memory for use by the program. (2) In APPC, a verb that assigns a session to a conversation. Contrast with deallocate.

APING

(1) The APPC Connectivity Tester facility. (2) The client transaction program for the APPC Connectivity Tester facility.

APINGD

The server transaction program for the APPC Connectivity Tester facility.

APPC verb

The mechanism by which a program accesses APPC. Each verb supplies parameters to APPC.

application programming interface (API)

The set of programming language constructs or statements that can be coded in an application program to invoke the specific functions and services provided by an underlying operating system or service program.

application TP

An application program that uses APPC to accomplish tasks for users and exchange data with other TPs in an SNA environment.

ASCII

American Standard Code for Information Interchange. A coding scheme that assigns numeric values to letters, numbers, punctuation marks, and certain other characters.

asynchronous verb completion

Processing of an SNA verb where the initial API call returns immediately, so that the normal operation of the program is not blocked while processing completes. When the verb completes, the application is notified through a Windows message or event. Contrast with synchronous verb completion.