HP-UX SNAplus2 MS Programmer's Guide

Writing MS Applications

Description of the MS API Entry Points

Chapter 238

SNAplus2 calls the supplied callback routine to

indicate when the verb processing completes. The

application can then examine the VCB parameters.

Using the Asynchronous Entry Point

When using the asynchronous entry point, note the following:

• If an application speciﬁes a null pointer in the

comp_proc

parameter,

the verb will complete synchronously (as though the application

issued the verb using the synchronous entry point).

• If the call to ms_async is made from within an application callback,

specifying a null pointer in the

comp_proc

parameter is not

permitted. In such cases, SNAplus2 rejects the verb with primary

return code value AP_PARAMETER_CHECK and secondary return code

value AP_SYNC_NOT_ALLOWED.

• The application must not attempt to use or modify any parameters in

the VCB until the callback routine has been called.

• Multiple verbs do not necessarily complete in the order in which they

were issued. In particular, if an application issues an asynchronous

verb followed by a synchronous verb, the completion of the

synchronous verb does not guarantee thatthe asynchronous verb has

already completed.

The Callback Routine Speciﬁed on the ms_async

Entry Point

When using the asynchronous MS API entry point, the application must

supply a pointer to a callback routine. SNAplus2 uses this callback

routine both for completion of a verb and also for returning MS data and

status indications. The application must examine the

opcode

parameter

in the VCB to determine which event is contained in the callback

routine.

This section describes how SNAplus2 uses the callback routine and the

functions that the callback routine must perform.

Callback Function

MS_CALLBACK (*comp_proc);

typedef void (*MS_CALLBACK) (

unsigned long target_handle,