SNMP messages from Win_Events are truncated

Products

• Automation Point

Issue/Introduction

When processing SNMP messages via AXCRULES from the Win_Events session and passing the message to a rexx program via the &MSG reserved variable, the message appears truncated.

However, the entire contents of the message can be seen when looking at it in the Windows Event Viewer.

There is no description of a limitation of message length nor a configuration change to prevent truncation in the manuals.

Environment

Release : 11.7

Component : Automation Point

Resolution

There is no workaround for the limitation of 500 characters per SNMP trap message by the means of AP as long as it's required to preserve the message undivided.

Additional Information

There is a way how to receive an SNMP message longer than 500 characters, but it means processing the message outside of AP.
To do this, it's needed to adjust the message processing as outlined below.

AP uses a suite of tools called NET-SNMP to process SNMP messages.
For the purpose of receiving SNMP trap message AP runs snmptrapd.exe.
The tool (snmptrapd.exe) can be configured to forward any received SNMP trap message to an external tool.
The external tool can very well be a Rexx script running in the AP environment.
In order to to configure an external SNMP trap message processing tool edit file "C:\usr\etc\snmp\snmptrapd.conf" and add the following line to it:
snmptrapd.conf:
...
traphandle default "C:\Program Files (x86)\CA\CA Automation Point\bin\asorexx.exe" forward.rex

where forward.rex is a sample Rexx script which collects and processes the SNMP trap message.
 
forward.rex:
 
msg = ""
do forever
 temp = LINEIN()
 if temp == "" then leave
 msg = msg || temp
end
say "Msg = " || msg
...

at the end of the script execution the Msg variable contains the whole SNMP trap message.
There are several ways how to send a value into an AP session such as ADDRESS AXC MSG, SESSCMD and WTO commands.
These, however,  apply the same or even stricter rules to the parameter value length and hence cannot be employed to obviate the message truncation.

Other than the aforementioned the only way to increase the ability of AP to process long (>500 chars) SNMP trap messages is to change the AP code, which is going to be lengthy process because of extensive internal dependencies in AP.
It requires an Idea in Broadcom Communities for this (Enhancement Request)