Cloudware Technologies - Guide to Cloud Computing for Business and Technology Managers - page 315

using the binding details in the service description to locate and contract to
the service in either of these two ways:
1. Direct invocation of the Web Service by the Web Services requestor
using the technical information included in the description of the
service.
2. Mediation by the discovery agency for invoking the Web Service. In
this case, all communication between the Web Services requestor
and the Web Services provider goes through the Web Services regis-
try of the discovery agency.
15.3.2 Roles in SOA
Corresponding to the three operations in the SOA, there are three primary
roles, namely, service provider, the service registry, and the service requestor.
15.3.2.1 Web Services Provider
The Web Services provider is responsible for publishing the Web Services
it provides in a service registry hosted by a service discovery agency. This
involves describing the business, service, and technical information of the
Web Service and registering that information with the Web Services registry
in the format prescribed by the discovery agency.
From a business perspective, the Web Services provider is the organization
that owns the Web Service and implements the business logic that underlies
the service. From an architectural perspective, this is the platform that hosts
and controls access to the service.
15.3.2.2 Web Services Registry
Web Services registry is a searchable directory where service descriptions
can be published and searched. Service requestors find service descriptions
in the registry and obtain binding information for services. This informa-
tion is sufficient for the service requestor to contact, or bind to, the service
provider and thus make use of the services it provides.
The Web Services discovery agency is responsible for providing the infra-
structure required to enable the three operations in the Web Services archi-
tecture as described in the previous section: publishing the Web Services by
the Web Services provider, searching for Web Services by the Web Services
requestors, and invoking the Web Services.
15.3.2.3 Web Services Requestor
The next major role in the Web Services architecture is that of the Web
Services requestor (or client). From a business perspective, this is the