SNAX/APN Application Programming Manual

SNAX/APN Application Programming Manual—420111-001

4-1

The SNALU Interface

This section discusses the use of the SNAX Application Logical Unit (SNALU)

interface in a SNAX/APN environment. Additional information about the SNALU

interface is contained in:

•

Appendix A, Migrating Applications From SNAX/XF and SNAX/CDF

to SNAX/APN,

•

Appendix B, Handling Errors in SNAX/APN Applications,

•

Appendix C, Logic Flows and Internal Formats When Using SNALU,

An application interacts with the SNALU interface by using a subset of file-system

procedure calls: AWAITIO, CANCEL, CANCELREQ, CLOSE, DEVICEINFO,

FILEINFO, OPEN, and WRITEREAD.

SNALU Interface and SNA

SNA provides a layered approach to the implementation of a data communications

network. Figure 4-1 shows that the SNALU interface provides the lower two SNA

functional layers (data link control and path control) and some transmission control

functions (like validating RU lengths). An application using the SNALU interface

performs some transmission control and higher-level functions, like SNAX header

formatting, sequence number maintenance, send/receive pacing and some error

recovery. For information about user-supplied SNA functions, see the IBM manual

Systems Network Architecture: Format and Protocol Reference: Architectural Logic.