Information Technology Reference
In-Depth Information
addition, developers can use ECS for managing shopping carts of products for
purchases made through Amazon. This allows the receiving of commissions on
sales that originate with another Web site or application. By use of this func-
tionality, the technical handling of purchases is then completely transferred to
Amazon (although purchasing directly through ECS is not supported). ECS
is a read-only system, and so product data cannot be sent back to Amazon
via ECS. The operations offered by ECS can be categorized as enquiries about
operations for product data, manipulation of shopping cart, enquiries about
customer content and seller information, and auxiliary operations.
The ECS Web service is offered as a WSDL description, i.e. the opera-
tions required for consumption with the datatypes expected, along with the
technical endpoint, accompanied by a Web page with additional explanations
in order to enable developers to utilize ECS correctly. Although this allows
the ECS functionalities to be utilized and integrated within other B2C e-
commerce applications, developers need to manually study the explanations
on the Web page and inspect the WSDL description in detail. However, hav-
ing a semantic description of the Web service would enable automated usage
by the technologies presented in the preceding sections. Hence, the following
depicts the semantic description in WSMO.
WSMO Description of the ECS Web Service
The semantic annotation of the WSMO description of the Amazon ECS Web
service was achieved by analyzing its WSDL and XML Schema definitions
and lifting them to an ontological description. We refer to [77] for the com-
plete description, along with an explanation of how this was done. Because of
space limitations, we shall not display the domain ontology, and restrict our
examinations to the facilities for product search; the Amazon technology is
very mature in these respects and hence there might be the most interesting
aspects for incorporation into other B2C e-commerce solutions.
First, we study the functional description of ECS, modeled by a capa-
bility in WSMO, as shown in Listing 11.1. This defines the preconditions of
the ECS Web service, capturing all its inputs. Here, however, we display only
those related to product search. ECS can accept any of the inputs at any given
point in time, so that the overall precondition is defined as a disjunction of
all the possible inputs. The postconditions of a WSMO capability define the
conditions that hold after the Web service has been executed. For the Amazon
ECS - as well as for Web services in general - the postcondition depends on
the precondition: a specific response can be provided only if the correspond-
ing request has been provided as an input to the service. In consequence, the
postconditions are defined as implication rules: if the request provided as in-
put is of a specific type that satisfies the precondition, then the corresponding
response will be given. The overall ECS postcondition is denoted by a conjunc-
tion of the postconditions for distinct requests. Because of space limitations,
we display only the postconditions for search by author and keywords. The
Search WWH ::
Custom Search