Nancy, I'm sorry that I wasn't clearer about the structure and future of
web service management in the printer space. Thank you for the
question. Clarification follows, I hope. I think this deserves a real
answer, not just yes-no. And I think a lot of people need to hear the
answer. I hope you don't mind my sending this reply to a broader
audience.
- 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.
rick
----------------------
Richard_Landau(at)dell(dot)com, Stds & System Mgt Architecture, CTO
Office
+1-512-728-9023, One Dell Way, RR5-3, MS RR5-09, Round Rock, TX 78682
________________________________
From: nchen at okidata.com [mailto:nchen at okidata.com]
Sent: Thursday, May 15, 2008 09:49
To: Landau, Richard
Subject: CIM object requirement for WS-Management
Hi Rick,
I remember at the beginning of WIMS-CIM alignment project, you mentioned
that in the future WS-Managet will only accept CIM objects.
Is this still true? I don't see this compliance statement in
WS-Management spec, neither the claim at DMTF CIM web site. Would you
please verify this remains true? If so, do a device wishing to be
managed by WS-Management need to embedded their management data in CIM
objects within the device? I see a lot of overhead in this.
-Nancy
------------------------------------------------
Nancy Chen
Principal Engineer
Solutions and Technology
Oki Data
2000 Biships Gate Blvd.
Mt. Laurel, NJ 08054
Phone: (856) 222-7006
Emal: nchen at okidata.com
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