RE: [wsdm] [OMod] William's AI: endpoint -> service

["Sedukhin, Igor S" <Igor.Sedukhin@ca.com>]

William,

I think your text is just fine with the exception of the following statement.

[The presence of a collection mechanism will also allow a manager to access  a set of endpoints (representing a service) as one entity. Finally, the MOWS specification will identify  in a non-normative way capabilities of a service and how they can be derived from the capabilities of  the endpoints that compose them.]

I think it is too early to presume that we do collections and non-normative spec of managing web services in addition to endpoints before january 2004. May be we need to discuss this with a larger group. I propose that we don't include those statements so far and adopt the rest of your text now.

Also a few minor corrections:

[dereferencable URL] 
I think URL is always "dereferencable", URN may not be. So saying just URL is sufficient.

[Nevertheless, the notion of endpoint is  relatively unambiguous.]
I think it is just unambiguous per WSDL pec, isn't it? One important point is missing here is that an endpoint is uniquely idenifiable by a URI and that counts towards being unabiguous.

[... such as UDDI, that do not use the same mechanism.]
I think one important thing that is missing in that paragraph is the following. I propose to add it.
"For visibility and other concerns, many WSDL documents may include descriptions of the same service with different endpoints. In certain cases WSDL document may include a description of a service with endpoints offered by different providers." This applies to both WSDL 1.1 and WSDL 2.0 equally. I believe this to be very important.

[..WSDM MOWS specification defines endpoints..]
It should say "defines manageability of endpoints".

-- Igor Sedukhin .. (igor.sedukhin@ca.com)
-- (631) 342-4325 .. 1 CA Plaza, Islandia, NY 11788

-----Original Message-----
From: VAMBENEPE,WILLIAM (HP-Cupertino,ex1) [mailto:vbp@hp.com] 
Sent: Tuesday, October 28, 2003 1:10 PM
To: wsdm@lists.oasis-open.org
Subject: [wsdm] [OMod] William's AI: endpoint -> service


Here is some text on mapping endpoints to services to fulfill my action item...

William




A Web service endpoint is defined as the implementation of a WSDL 1.1 portType with a given WSDL 1.1  binding at a dereferencable URL. In a WSDL
1.1 document, it corresponds to a port element. There is no  guarantee that only one endpoint corresponds to a given URL. Nevertheless, the notion of endpoint is  relatively unambiguous.

WSDL 1.1 defines a service element as a collection of port elements. There is no requirement that these  ports have anything in common in terms of portTypes, bindings or endpoint URLs (the current draft of  WSDL 2.0 specification requires that all ports in a service implement the same interface - the new name  for portType). Therefore, WSDL 1.1 defines a Web service as any collection of endpoints that one chooses  to group together in a service WSDL 1.1 element. The same set of endpoints can be grouped at the same  time in many permutations of services by WSDL authors. In addition, other specifications can claim to  define Web services, such as UDDI, that do not use the same mechanism.

Implementing management at the Web service level therefore offers challenges in terms of identifying  services. It also offers implementation challenges, for example if all the endpoints in a service are  not implemented in the same environment (e.g. one endpoint inside the firewall and one endpoint outside  of the firewall). Also, in many cases managers want to manage Web services at the granularity level of  the endpoint: they need to know when one endpoint goes down and how many messages a specific endpoint  has processed for example. At the same time, there are many cases where the manager wants to think at  the Web service level and doesn't care about the endpoint. For example, a business manager using a  business dashboard doesn't care whether the purchase orders arrive via the HTTP or the SMTP binding of  the purchase service, or whether they arrive via the US server or its European mirror.

In recognition of these requirements, the WSDM MOWS specification defines endpoints as the base building  block for managing Web services. It also ensures that information is available for the manager to  reconstruct the service-level view that some users require. This includes allowing the manager to  request from the endpoint a list of WSDL documents that the endpoint knows of (to identify services that  this endpoint is part of). It also includes allowing endpoints to establish relationships linking them  as part of the same service. The presence of a collection mechanism will also allow a manager to access  a set of endpoints (representing a service) as one entity. Finally, the MOWS specification will identify  in a non-normative way capabilities of a service and how they can be derived from the capabilities of  the endpoints that compose them.


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