Cloudware Technologies - Guide to Cloud Computing for Business and Technology Managers - page 314

description of a Web Service, three basic categories of information are
necessary:
1. Business information : information regarding the Web Service pro-
vider or the implementer of the service
2. Service information : information about the nature of the Web Service
3. Technical information : information about implementation details and
the invocation methods for the Web Service
Registration deals with storing the three basic categories of descriptive
information about a service in the Web Services registry. For Web Services
requestors to be able to find a Web Service, this service description informa-
tion needs to be published with at least one discovery agency.
15.3.1.2 Find Operation
Finding the desired Web Services consists of first discovering the services
in the registry of the discovery agency and then selecting the desired Web
Service(s) from the search results.
Discovering Web Services involves querying the registry of the discovery
agency for Web Services matching the needs of a Web Services requestor; a
query is executed against the Web Service information in the registry entered
by the Web Services provider. A query consists of search criteria such as type
of service, preferred price range, what products are associated with this ser-
vice, with which categories in company and product taxonomies this Web
Service is associated, as well as other technical service characteristics. The
find operation can be specified statically at design time to retrieve a service's
interface description for program development or dynamically (at runtime)
to retrieve a service's binding and location description for invocation.
Selection deals with deciding about which Web Service to invoke from the
set of Web Services the discovery process returned. Two possible methods
of selection exist: manual and automatic selection. Manual selection implies
that the Web Services requestor selects the desired Web Service directly
from the returned set of Web Services after manual inspection. The other
possibility is automatic selection of the best candidate between potentially
matching Web Services. A special client application program provided by
the Web Services registry can achieve this. In this case, the Web Services
requestor has to specify preferences to enable the application to infer which
Web Service the Web Services requestor is most likely to wish to invoke.
15.3.1.3 Bind Operation
The final operation in the Web Services architecture and perhaps the most
important one is the actual invocation of the Web Services. During the bind-
ing operation, the service requestor invokes the Web Service at runtime