-
WS-Management is not restricted to transferring CIM-based objects. The WS-Man protocol can be used with any
sort of objects. In this sense, it
is like SNMP without MIBs. WS-Man
includes Get, Put, Enumerate (and so forth) just as SNMP includes Get, Set,
GetNext (and so forth).
- A
protocol is not sufficient to manage a device. You still have to define the management
data objects that are to be manipulated by the protocol operations. For SNMP, one defines MIBs, lots of
them, to specify the syntax and semantics of the data to be manipulated. For WS-Man, the only public, standard
definitions so far are CIM objects.
- DMTF
(dmtf.org) publishes the WS-Man protocol standard as its document DSP0226. It also publishes the WS-Man CIM Binding
spec, which describes how CIM objects are to be named and manipulated using
WS-Man, as DSP0227. And the XML
representation of CIM objects for use by web services is described in
DSP0230. The entire CIM schema is
also published by DMTF and updated three times per year.
- PWG
has just invested considerable effort in defining the CIM classes for a Printer
device to match the model of the Printer MIB and the Semantic Model. The CIM schema v2.19 now contains about
fifteen classes and a hundred properties that very closely parallel the Printer
MIB. So, theoretically, it would
now be possible to manage a printer using a modern web service,
WS-Management.
- As a
proof of the mapping from SNMP to CIM schema, I am building a prototype of a
proxy provider for a CIM server.
This will take SNMP data from a network printer and re-publish it in a
CIM Object Manager ("CIMOM," such as WMI on Windows) using these new
printer-related classes.
- If
someone wants to invent another mapping of the industry-standard printer
management data to some other data model, he/she is free to do that. However, the result won't be any smaller
or simpler than the one that was in the Printer MIB -- and is now in the CIM
schema. Sure, it's possible, but
why bother? We already invested the
man-year or two necessary to define that data in a published standard. Any sensible implementer will simply use
what is available.
- Many
of us are convinced that web services will become popular management protocols,
and over time will become the dominant protocols. If something is not manageable by a web
service protocol, at some point in the future, on some set of corporate
networks, it simply won't be manageable at all.
-
Overhead? Sure, everything has
overhead. The SNMP agent in a
printer has overhead, and manufacturers complained about that expense when it
was first implemented. The HTTP web
service in a printer has overhead, and manufacturers complained when it was
first implemented. So, too, the
WS-Man service management agent in a future printer will have overhead, and we
will complain about that. But if we
want a device to be manageable in corporate and educational networks, we have no
choice. Customers insist on
out-of-band management as a feature of all network devices.
- I will
point out that, as of late this year, every new business desktop and laptop
computer system will have a complete, WS-Man-based, out-of-band, management
agent, using (dozens of) CIM classes to transfer data. Look for
"DASH" in the feature list. The major vendors will be using
chips developed by a number of companies, including all the major NIC and
management controller companies, in any new system that requires remote
management. The overhead for this
agent is small, and largely in silicon.
So, to
answer your question, No, WS-Management is not *required* to use CIM objects,
but it *can* use CIM objects. And
CIM objects represent a very rich and growing set of management objects for
computer systems and peripherals.
If one wants to include web service management in a device, the
WS-Management and CIM schema standards are already available.