4.9   View Tables

In SNMPv1 the concept of views was described, but no mechanism was specified to implement a view. In the party model version of SNMPv2, a simple and powerful method, the view table, was specified in RFC 1445.

In the current WindNet implementation, the notion of a view table is provided to the agent designer to allow for the same compatibility as in the SNMPv2 specifications. These facilities are made available to the user without the complexities of SNMPv2 party tables. For more information, see RFCs 1445 and 1447.

The view index for the RFC 1445 view scheme is chosen by the user-defined routine snmpIoCommunityValidate( ). The routine should assign an integer to the view_index field of the SNMP_PKT_T structure. This number is the index in the view table of the view to use. The view table should already have been populated, probably at initialization time.

The process of selecting a view index is normally based on the community string in the input packet. It is entirely up to the user to select the policy used to do this mapping from the community strings to the view indices. The agent does not require any configuration files for this purpose, though the user is free to implement such a scheme if desired.

For example, you might have an initialization file containing view table and community information and used to create the view tables and any associated data structures to implement the community string to view index mapping.

The default implementation provided in snmpIoLib uses hardcoded items.