Re: [wsdm] Discovery Scenarios [fred]

[Fred Carter <fred.carter@amberpoint.com>]

I think John covered most things (Thanx, John).

Thus quoth John DeCarlo (~ 21-May-04 8:01 AM ~)...

> David,
> 
> 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 
> manageable.
> 
> 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.

Thus far, WSDM has concentrated on the interface between the management 
application (generally referred to as the "manager") and the 
manageability provider.  We haven't realy looked much at (except for a 
few 'glancing blows' about being notified that a new entity exists). 
Perhaps we should, but the issue has been primarily standardizing the 
manager/manageability provider endpoint interface.

> 
>>  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).

Just to be clear on terminology, is your "resource manager" a 
manageability provider, or a management application?  I think that 
John's answering the question where "resource manager" == manageability 
provider.
> 
> 
> 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.

True enough, but they aren't currently doing so through the web services 
paradigm.  In said paradigm, one locates an endpoint via either via 
implicit knowledge or a registry, where a registry may be a UDDI thing, 
a wsdl file, a wsil resource, etc.  (I think this is the "double 
triangle" of the W3C Web Service Architecture.)

That may change, but that's the WSA defines things.

I think that's OK.  The problem is that "resources" introduce another 
layer of indirection/abstraction, and we're trying to determine how to 
resolve issues associated therewith.

> 
> 
> 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 
> discovery.
> 
> 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?
> 


-- 
Fred Carter / AmberPoint, Inc.

mailto:fred.carter@amberpoint.com
tel:+1.510.433.6525 fax:+1.510.663.6301