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README for demo_module_10
***********************************************************************
This example demonstrates a module design that handles long running
data collections so that their values can be polled by an SNMP manager.
The example also shows how to implement objects that normally would block
the agent as it waits for external events in such a way that the agent can
continue responding to other requests while this implementation waits.
This example uses the following features of SMA:
- Setting the delegated member of the requests structure to 1 to indicate to
the agent that this request should be delayed. The agent queues this request
to be handled later and then is available to handle other requests. The
agent is not blocked by this request.
- Registering an SNMP alarm to update the results at a later time.
- Use of a status variable to communicate the status of a data collection to
the polling SNMP manager.
- Use of a refreshTime variable to return the date and time that the data
collection completed.
How to Build the demo_module_10 Code Example
============================================
The demo_module_10 code example includes the following files, by default
located in the directory /usr/demo/sma_snmp/demo_module_10.
Files:
Makefile - makefile to build the demo_module_10.so shared library file
demo_module_10.c - module source code
demo_module_10.h - module header file
SDK-DEMO10-MIB.txt - MIB file
get_status - Script that gets the value of the status variable
get_refreshtime - Script that gets the date and time of the current data
collection get_data - Script that gets the data returned by the data collection
set_data - Script sets the value of the status variable to 0, which starts a
new data collection
To set up your build environment for the demo:
1. Copy the demo code to a directory for which you have write permission.
For example:
% cp -R /usr/demo/sma_snmp/demo_module_10 /home/username/demo
2. Create a lib directory that you can use to store shared object libraries
that you generate from demo code examples, if you have not already done so.
For example:
% mkdir /home/username/demo/lib
3. Create a mibs directory that you can use to store MIB files for the demo
code examples, if you have not already done so.
For example:
% mkdir /home/username/demo/mibs
4. Set the CC environment variable to the location of the C compiler to be
used.
For example, if you are using Sun ONE Studio:
% setenv CC /opt/SUNWspro/bin/cc
5. Set your PATH environment variable to include the appropriate paths, so that
needed binaries can be found during the compilation process.
For example, in the csh:
% setenv PATH .:/usr/bin:$PATH
To build the example:
1. Change to the directory where you copied the demo module files.
For example:
% cd /home/username/demo/demo_module_10
2. Use the make command to generate object files.
If you are running the 64-bit SPARC Solaris kernel, type:
% /usr/ccs/bin/make
If you are running the 32-bit SPARC Solaris kernel, type:
% /usr/ccs/bin/make ARCH=32
If you are running the Solaris x86 kernel, type:
% /usr/ccs/bin/make ARCH=32
3. Copy the module shared library object to the lib directory you created.
For example:
% cp demo_module_10.so /home/username/demo/lib
4. Copy SDK-DEMO10-MIB.txt to the mibs directory you created for the demos.
For example:
% cp SDK-DEMO10-MIB.txt /home/username/demo/mibs
Setting Up Agent to Run the demo_module_10 Module
=================================================
1. As root, edit the agent's configuration file /etc/sma/snmp/snmpd.conf,
and insert a dlmod statement for the module. This statement enables the
agent to load the module.
For example:
dlmod demo_module_10 /home/username/demo/lib/demo_module_10.so
2. As root, start the SMA snmp agent. If the agent is already running,
stop and restart it in debug mode.
For example:
# /etc/init.d/init.sma stop
# /usr/sbin/snmpd -Ddemo_module_10
The optional -Ddemo_module_10 argument sends debugging statements from
demo_module_10 to the /var/log/snmpd.log file. You can also use the -L
and -f options to send debugging statements to the screen instead.
Testing the Code Example
========================
1. Set your MIBS and MIBDIRS environment variables to
include the appropriate paths.
For example, in the csh:
% setenv MIBDIRS .:/home/username/demo/mibs:/etc/sma/snmp/mibs
% setenv MIBS +SDK-DEMO10-MIB
Note that step 1 is not required, but it enables snmpget to access the MIB
to provide variable names instead of OIDs in its output.
2. Run the get_status script to get the default value of
the status variable.
% get_status
SDK-DEMO10-MIB::status.0 = INTEGER: 2
An SNMP manager would typically poll the status variable
of devices that generate long running data collections, until
a value 2 is returned, which indicates that the collection is
complete and the data is ready to get.
status has a default value of 0, which means no data collection
has been started, so the module starts a new collection.
When the collection completes, status is set to 2.
3. Run the get_refreshtime script to get the date and time
of the data collection.
% get_refreshtime
SDK-DEMO10-MIB::refreshTime.0 = STRING: Fri Jul 18 12:36:56 2003
After retrieving the date and time, the SNMP manager can decide whether the
date of the data collection is acceptable. If the manager needs more recent
data, it can set the status variable to 0 to start a new collection. In this
example, the manager wants more recent data.
4. Set the status variable to 0 to start a new collection, as follows:
% set_status
SDK-DEMO10-MIB::status.0 = INTEGER: 0
Note that SET requests through this object will take longer,
since the delay is applied to each internal transaction phase,
which could result in delays of up to 4 times the value of this object.
For example, initially, the default value is
1 second. Therefore, specify a 3 second timeout value on the
snmpset command line.
5. Run the get_status script again to get the status value.
% get_status
SDK-DEMO10-MIB::status.0 = INTEGER: 2
6. Run the get_data script to get the data resulting from
the data collection, for example:
% get_data
SDK-DEMO10-MIB::longRunScalar.0 = INTEGER: 325
7. Open two terminal windows so you can run two scripts at the same time, as
follows:
In the first window, run the get_status script:
% get_status
SDK-DEMO10-MIB::status.0 = INTEGER: 2
In the second window, run the walk_demo_module_10 script:
% walk_demo_module_10
SNMPv2-MIB::sysDescr.0 = STRING: SunOS myhost 5.10 s10_35 sun4u
SNMPv2-MIB::sysObjectID.0 = OID: NET-SNMP-TC::solaris
DISMAN-EVENT-MIB::sysUpTimeInstance = Timeticks: (497128) 1:22:51.28
SNMPv2-MIB::sysContact.0 = STRING: "Administrator's Name"
SNMPv2-MIB::sysName.0 = STRING: myhost
SNMPv2-MIB::sysLocation.0 = STRING: My Town
SNMPv2-MIB::sysORLastChange.0 = Timeticks: (8) 0:00:00.08
SNMPv2-MIB::sysORID.1 = OID: IF-MIB::ifMIB
...
This example demonstrates that the agent is not blocked and does respond to
the snmpwalk request, while the snmpget request executed in the first
window is still pending.