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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.