Context Table

The vacmContextTable table stores the contexts that are available locally. A context is the selector of management information. A single managed object can be in several different contexts. For example, consider a single module designed to monitor the status of a printer. For a network with several printers, multiple instances of this module can be implemented, with each instance containing a unique printer name. The printer name in this case is the context.

A single SNMP entity can have access to several contexts.

The vacmContextTable table is indexed by a contextName. Each of its rows gives the context name in the form of a unique, readable string, vacmcontextName.

The System Management Agent looks in the vacmContextTable for the contextName found in the scopedPDU. For information on the scopedPDU, see SNMP Versions. If the System Management Agent does not find the contextName of a particular message in the vacmContextTable, access is denied. In this case, a return value of noSuchContext is returned.

If the contextName exists, access checking continues, as shown in Figure 4–2. An example of typical entries in a vacmContextTable is shown in Example 4–1.

Example 4–1 Creating Typical Context Table Entries

Some typical vacmContextTable entries, created by a module, are:

SNMP-VIEW-BASED-ACM-MIB::vacmContextName."fileX" = STRING: fileX
SNMP-VIEW-BASED-ACM-MIB::vacmContextName."fileY" = STRING: fileY

The contextNames in this example are fileX and fileY.

Contexts are further explained in the Solaris System Management Agent Developer’s Guide. To illustrate the concept of contexts, a demo module is supplied with the System Management Agent. This demo module shows the importance of contexts for implementing multiple instances of a module. For more information, see Implementing Multiple Instances of a Module in Solaris System Management Agent Developer’s Guide.