Challenges and Experiences in Transitioning Management Instrumentation from Command-Oriented to Model-Driven - Advances in Network-Embedded Management and Applications - page 4

instrumented feature. These action functions are intimately linked with the
parse result of their associated command line and the instrumentation they
access.
The action function for all CLIs that manipulate data and services of a
management instrumentation component provide the component's implicit
management model. Transitioning to a model-driven system, designers define
and impose a model outside of the command-oriented framework and based
on instrumentation domain knowledge and management requirements. They
ultimately face the issue of adapting their defined model to the implicit model
of the CLI implementation. Difficulties arise when the actual instrumentation
capabilities of the implicit model are not reflected in the defined model they
are imposing and vice-versa.
A similar example of this impedance mismatch can be seen in today's
management instrumentation environment in the area of SNMP MIB support.
An SNMP MIB is a model specified outside of the domain of any specific
instrumentation implementation. A MIB can specify access to management
data and service capabilities that may or may not be reflected in the system
instrumentation. Implementers of SNMP MIB interfaces must provide
mapping between the imposed model of data and services requested by the
MIB and the model implicit in the implementation.
Resolving this impedance mismatch - the differences between the implicit
and imposed management instrumentation models is perhaps the largest and
most complex challenge of the command-oriented to model-driven transition.
3 Design Considerations
Model-driven management instrumentation designs are approached from a
practical inverse of command-oriented designs due to their focal differences.
A command-oriented design focuses on particular management interface
commands and their associated instrumentation with respect to a particular
feature. Conversely, a model-driven design focuses on the feature
instrumentation to be made available for all management interfaces. This
section discusses key design considerations when transitioning from a
command-oriented to a model-driven design.
Figures 1 and 2 below provide a comparison of command-oriented and
model-driven architectures. The command-oriented architecture depends
upon access to feature instrumentation data being tightly coupled with the
management interface. In comparison, the management interfaces of the