HP-UX SNAplus2 R7 LUA Programmer's Guide

Designing and Writing LUA Applications

LUA Entry Points for HP-UX Applications

2 Designing and Writing LUA Applications

The information contained in this chapter will help you write LUA application programs. The following topics are

covered:

• LUA entry points for HP-UX applications

• LUA entry points for Windows applications

• Issuing an LUA verb

• SNA information

• Conﬁguration information

• HP-UX environment considerations

• Windows environment considerations

• Writing portable applications

2.1 LUA Entry Points for HP-UX Applications

UNIX

HP-UX Applications access LUA using the RUI or SLI function call, specifying the address of a Verb Control

Block (VCB) containing information for an LUA verb. SNAplus2 returns control to the application immediately.

The returned VCB contains a value indicating whether verb processing is still in progress or has completed.

• In some cases, verb processing is still in progress when control returns to the application; SNAplus2 then uses

an application-supplied callback routine to return the results of the verb processing.

• In other cases, verb processing is complete when SNAplus2 returns control to the application; SNAplus2 does

not use the application’s callback routine. This applies particularly if the verb failed LUA’s initial parameter

checks or state checks and so cannot be acted on.

• For SLI_OPEN, if the initial checks succeed, the SLI function call returns a non-zero value representing the

session ID of the new session. SNAplus2 then uses the application-supplied callback routine in the same way

as for other verbs. The application can use the new session ID to issue a limited range of subsequent verbs on

the session, without waiting for the callback routine to be called. For details of which verbs can be issued in

this situation, see Section 5.3.4, Interaction with Other Verbs.

Note

Because of the way HP-UX callback routines operate, it is possible that the application’s

callback routine will be called before control returns to the application from its initial

function call for the verb. This means that, if the callback routine modiﬁes or deletes the

returned VCB, the program’s main thread of execution may be unable to check the VCB

parameters to determine that the verb is operating asynchronously. You may need to take

account of this in your application design.

The entry points RUI and SLI are deﬁned in the LUA header ﬁle /usr/include/sna/lua_c.h.