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Subject: Re: [wsdm] Discovery Scenarios [fred]


See inline.

David E Cox wrote:

> Hi Fred,
>   Thanks for writing this up.  To me, the confusion starts before your 
> scenario begins.  

Ah ha!

>   How did the managed resource get installed into the system?

There are at least two items to consider here.  1) Installing the 
resource and making it available to consumers.  2) Making the resource 

1) is out of scope for WSDM

2) is not well defined how it happens.  (Probably because how you make a 
disk drive manageable will differ from how you make a Web Service 
manageable, and even the Web Service may provide its own manageability 
or rely on the Execution Environment or something else.) But essentially 
it involves some method where the Manageability Provider is linked 
enough to the resource to start providing manageability for it.

In the last call, we talked about having an Event defined that says a 
resource has now been made manageable.

Otherwise, we really don't know what resources have been made manageable 
without talking to the manageability provider.

Not that there aren't lots of good ideas on changing that, like perhaps 
registering all EPRs somehow when the resource is made manageable. 
Maybe the registries would just subscribe to the "JustNowMadeManageable" 
Event, as any other consumer would.

>  Who installed it?  

Again, make the resource available for consumers is out of scope for 
WSDM.  Only making it manageable is in scope.

The answer is similar to the last question.

> Who published its management interface, and to where? 

This depends on who provides manageability for the resource.  The 
management interface is defined in WSDL and may already have been 
published in a registry somewhere, or the URL to the WSDL has been 
provided somehow.

So the manageability provider (whoever that happens to be, and there may 
be more than one) publishes the manageability interface in WSDL.

>  Who made the resource known to the resource manager (in some cases they 
> will be installed concurrently, in some cases they will be separate).

This is the basic question.

Maybe no one made the resource known the the resource manager.  So it is 
required to continually do some sort of discovery.

Maybe if WSDM or another group defines a "just made manageable" event, 
the resource manager could just subscribe to it.

>   I think that part of the scenario is what drives the WSDL vs EPR 
> starting point.  I at least am confused about how/why a manager would be 
> given a WSDL file.  That's not typically the way a management tool would 
> discover a manageable resource.  It usually finds the resource first (by 
> looking in directories and registries, or by various scanning 
> techniques), then finds the manageability interface.  I'm not saying 
> that is right or wrong in the new Web Services model, but I would like 
> to understand that part of the scenario.

Let me word it another way.  Management tools are either pre-loaded with 
information about resources to manage, or they have to do some sort of 

One idea in the MUWS world is to simply discover the Manageability 
Endpoint WSDL.  Then query the Manageability Provider at that endpoint 
to find out what manageable resources there are there.

And where there are multiple manageability interfaces for one resource, 
the management tool may or may not care, and may or may not want to use 
Identity or Correlatable Names to determine if two resources are the same.

Does this answer your questions?


John DeCarlo, The MITRE Corporation, My Views Are My Own
email:      jdecarlo@mitre.org
voice:      703-883-7116
fax:        703-883-3383
DISA cube:  703-882-0593

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