Information Technology Reference
In-Depth Information
Second, user preferences can affect how the composition is per-
formed. A key component of Web service composition is the selection
of specific services used to realize the composition. In a typical
planning or reasoning process, primitive actions are selected for
composition based on their preconditions and effects. Similar to actions,
services are selected for composition based on functional properties
such as inputs, outputs, preconditions, and effects, but they should also
be selected based on domain-specific nonfunctional properties such as,
in the case of making a doctoral appointment, picking a doctor a patient
likes or trusts. By integrating user preferences into Web service
composition, preferences over services can be specified to lead to
the most desired solution.
Last but not the least, service composition is user-oriented, and it
should be centered on a user's needs. User preferences and constraints
are clearly parts of his/her needs. Therefore, we should not neglect them
so as to maximize the user satisfaction.
In a specific field, there are often some common requirements or
preferences, named as domain preferences. For example, in the field
of health care, according to different illness degree of a patient as
obtained via a diagnosis and risk assessment service, a doctor will
propose different treatment plans or prescribe different health care
services. The corresponding relationship between different health
care services and the results of diagnosis service is often fixed in such
a case, and, hence, this is domain preference for service composition.
Domain preferences can also be considered as a kind of user
preferences, and have significant impact on service composition in
a given field.
Next, we will pay more attention to user/domain preferences in
which we are interested in the field of health care. There are three types
of user/domain preferences of interest. The first type occurs when a user
prefers a class of services over another if certain conditions are met. For
example, Lucy prefers to go to a doctor's office by walking instead of
taking bus if the walking time is less than 20min and the weather is
pleasant. The second type occurs when a user prefers different services
when they have different conditions. For example, Lucy goes to see her
eye doctor if her eyes bother her; and her dentist if she has toothache.
The last type occurs when a user assigns priorities over services with
similar functionalities. For example, Lucy prefers to go to Lab A instead
of Lab B for test services if both are available.