SNMP++ is designed to support a variety of
operational modes. The modes of operation, allow for
Graphical User Interface (GUI) and console mode applications to be constructed.
GUI operational mode cooperates with the existing GUI event systems while
console mode operational mode allows for utilization of a custom event system
or no event system at all.
For MS-Windows usage, SNMP++ cooperates
with the MS-Windows messaging system. Blocked mode calls allow other messages
to be processed.
The X11 interface is identical to the
MS-Windows interface. Both MS-Windows and X11 versions of SNMP++ support
blocked and asynchronous modes of usage. One additional function call is
required for an X11 application to register its X11 context with SNMP++ in
order for SNMP++ to take advantage of X11’s event system. This enables XtAppMainLoop()
or similar functions to recognize and dispatch all asynchronous SNMP++ events
transparently.
·
The
context parameter passed in is returned from a call to XtAppInitialize().
·
The
return value is zero if the function is successful in registering with X11.
|
//----------------[ initialize
SNMP++ X11 Context ]-------------------------- int
SNMPX11Initialize( XtAppContext context); |
A third operational mode for SNMP++ is
that for constructing text mode console applications. These types of applications
can operate using either blocked mode or asynchronous mode calls. For blocked
mode calls, no additional SNMP++ function calls are needed. Asynchronous calls
require usage of some event system. For console operational asynchronous mode,
SNMP++ offers a set of function calls for reading the currently used file
descriptors (socket handles) which the caller may then utilize in their own
‘select’ call. If a SNMP++ file descriptor has a pending event, the caller may
invoke a routine to process all pending events.
SNMPGetFdSets
Used to determine which file descriptors will
potentially be active. The function fills in read, write and exception masks
which then can be passed to ‘select’.
|
//-------[ get file descriptor set from SNMP++
]------------------------------------ void SNMPGetFdSets(
int &maxfds,
// max # of fds
represented
fd_set &read_fds,
// mask representing read actions
fd_set &write_fds,
// mask representing write actions
fd_set &exceptfds);
// mask representing exception actions |
SNMPGetNextTimeout
Used to determine the time the next time-out event
will occur. This value can then be used to as the maximum interval that a
blocked operation, such as select, should wait before returning control. The
time-out calculation is based on the closest time of all user-registered
time-outs and SNMP retransmission time-outs.
|
//---------[ Get the next
time-out value ]---------------------------------------------------- unsigned
long int SNMPGetNextTimeout(
); // returns value in 1/100
of seconds |
SNMPProcessPendingEvents
Used to process all currently outstanding
events. This function
may call any callbacks associated with completed time-outs, file descriptors or
outstanding SNMP messages. This function does not block, it handles only events
outstanding at the time.
|
//------[ process pending
events ]---------------------------------------------------------- int
SNMPProcessPendingEvents(); |