HP-UX SNAplus2 R7 NOF Programmer's Guide

Introduction to the NOF API

NOF Indications

For more information about registering to receive indications, see Section 3.170, REGISTER_INDICATION_SINK.

For more information about individual indications, see Chapter 4, NOF Indications.

1.6.1 Conﬁguration Indications

An application can register to receive information about changes to the conﬁguration of a particular target (the

domain conﬁguration ﬁle, a running node, or an inactive node). This enables it to keep track of changes that can

be made by other NOF applications or by the administration programs. To do this, the application registers as for

other indications, specifying CONFIG_INDICATION as the requested indication type.

No speciﬁc VCB structure is associated with this indication type. Instead, when a change to the conﬁguration

occurs, SNAplus2 indicates this change to the application by sending a copy of the completed VCB from the NOF

verb that made the change.

For more information about conﬁguration indications, see Section 4.1, CONFIG_INDICATION.

1.6.2 SNA Network File Indications

An application can register to receive information about changes to the SNA network ﬁle sna.net on the master

server. This enables the application to keep track of changes to this ﬁle that can be made by other NOF applications

or by the command-line administration program. To do this, the application registers as for other indications,

specifying SNA_NET_INDICATION as the requested indication type.

Two VCB structures are associated with this indication type:

• ADD_BACKUP (indicating that a backup server has been added to the end of the ﬁle)

• DELETE_BACKUP (indicating that an unused backup server has been removed from the ﬁle)

Registering with a type of SNA_NET_INDICATION will return an ADD_BACKUP indication when a backup server

is added or a DELETE_BACKUP indication when a server is deleted; the application does not need to register

separately for each of these indications. In each case, the format of the indication is a copy of the completed VCB

from the NOF verb that made the change.

For more information about SNA network ﬁle indications, see Section 4.26, SNA_NET_INDICATION.

1.6.3 NOF Status Indications

SNAplus2 sends a NOF status indication to a registered NOF application when the application can no longer access

its target node or ﬁle (because the SNAplus2 software on the target computer has been stopped or because the

communications path to this computer has been lost). If the application is registered to receive indications from the

master conﬁguration ﬁle, this indication is also returned if another server takes over as master (and therefore the

target ﬁle is no longer the master conﬁguration ﬁle).

The application does not need to register explicitly to receive this indication; SNAplus2 returns it to any application

that has registered for any type of NOF indications on the appropriate target. The indication is returned on

the callback routine that the application supplied to the REGISTER_INDICATION_SINK verb (or to the ﬁrst

REGISTER_INDICATION_SINK verb, if the application has issued more than one).

After the application receives an indication that the target has failed, all subsequent verbs using the relevant target

handle will be rejected, except for DISCONNECT_NODE or CLOSE_FILE (to free the target handle). In addition,

any registrations for indications on this target handle will be lost; in order to continue receiving indications when

the target becomes available, the application must connect again to the target and register again for the required

indications.

For more information about NOF status indications, see Chapter 4, NOF Indications.