SNMPv2 to CORBA-IDL Translation

Outline of the Translation Algorithm

1. Map an SNMP Information module (SMI document) into an IDL module:

   • All interfaces, types and constant generated from a SNMP information module will be within the scope of the corresponding IDL module.

   • Declare the imported types in the information module as typedef of imported IDL type.

   • Declare two IDL interfaces, called SnmpNotifications and PullSnmpNotifications, (N in Mapping of SNMP Information Module to IDL ), if there is at least one NOTIFICATION-TYPE macro in the SNMP information module. The SnmpNotifications interface will be used for typed-push event communication and the PullSnmpNotifications interface will be used for typed-pull communication.

   • Declare a pseudo IDL interface, called DefaultValues (D in Mapping of SNMP Information Module to IDL ), if there is at least one OBJECT-TYPE macro with DEF-VAL clause; Pseudo IDL interfaces generate library code similar to the specification of the CORBA::TypeCode interface.

   • Declare a pseudo IDL interface, called TextualConventions (TC in Mapping of SNMP Information Module to IDL ), if there is at least one TEXTUAL-CONVENTION macro with DISPLAY-HINT clause.

2. Map each ASN.1 type into IDL type using the translation scheme defined in ASN.1 Type to CORBA-IDL Translation . A complex ASN.1 data type (used to describe PDUs for SNMP) may generate more than one IDL data type.

3. Map the value-specification of SYNTAX clause of TEXTUAL-CONVENTION macro, such as DisplayString, into an IDL type:

   • If DISPLAY-HINT clause is present, define two operations within the scope of the TextualConventions interface for converting the typed value to string and string to typed value.

4. Map the value of the invocation of the MODULE-IDENTITY macros into a constant IDL literal of type string.

5. Map the value of the invocation of the OBJECT-IDENTITY macros into a constant IDL literal of type string.

6. Map the value of the invocation of the OBJECT-TYPE macros into a constant IDL literal of type ASN1_ObjectIdentifier.

7. Each group is mapped with one IDL interface generated for the group (G in Mapping of SNMP Information Module to IDL ), and one IDL interface (T in Mapping of SNMP Information Module to IDL ), generated for entries of the each of the tables in the group:

   • Non-tabular variables of a group are mapped as IDL attribute within the scope of the IDL interface for the group. Column variables of the tables are mapped as attributes within the scope of the IDL interface for the entries of the table:

     • Use the descriptor of the OBJECT-TYPE macro of the corresponding variable as the identifier of attribute.

     • Acquire the IDL type of the attribute from the SYNTAX clause of the OBJECT-TYPE macro of the corresponding variable.

     • Acquire the mode of the attribute from the MAX-ACCESS clause of the OBJECT-TYPE macro of the corresponding variable.

   • If a DEFVAL cluase is present, define an operation within the scope of DefaultValues interface that returns the default value in typed form.

8. Map the value of the invocation of the NOTIFICATION-TYPE macros into a constant IDL literal of type ASN1_ObjectIdentifier:

   • Map the value-specification of the OBJECTS clause to an IDL struct which has one item for each variable in the OBJECT clause; the type of the items of the struct are defined as name-index-value triplet and the type of the value is derived from the variable being mapped.

   • Define an operation within the scope of SnmpNotifications interface of this module for typed-push event communication. The in parameters of the operation are source SNMP party OID, context OID, time-stamp of the event, and the IDL struct defined for the value-specification of the OBJECTS clause. Use the descriptor of the macro as the identifier for the operation.

   • Define two operations (try_<op> and pull_<op>) within the scope of the PullSnmpNotifications interface of this module, where <op> is the identifier of the corresponding operation in the SnmpNotifications interface. The parameters of the operations are same as push-event model but as out parameter.

9. Assign the OIDs of macros as RepositoryId (using #pragma ID declaration) to all IDL identifiers that corresponds to macro descriptor.

10. Ignore the macros related to MODULE-COMPLIANCE rules.

See SNMPv2 Information Module Macros for the mapping of each clause of the SNMPv2 macros.

Figure: Mapping of SNMP Information Module to IDL

SNMPv2 Application-specific Type Translation

For detailed description on mapping of ASN.1 type to IDL types including all primitive types, see ASN.1 Type to CORBA-IDL Translation .

Table: Mapping of SNMP ASN.1 Types