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

["VAMBENEPE,WILLIAM (HP-Cupertino,ex1)" <vbp@hp.com>]

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.