| Περίληψη: | Web services and service based architectures have created opportunities to establish
more flexible collaboration among different domains, such as smart cities, smart factories,
resource management, intelligent transportation, health and many other. The aim of
research efforts around web services is mainly to facilitate their handling and composition.
Service composition constitutes a challenging task of service provisioning as it can produce
new composite services with features not present in the individual ones. Also, service
composition can serve applications or users on-demand basis, so the ability to efficiently
select and integrate heterogeneous services at runtime becomes an important requirement
to the Web service provision. This is also due to the fact that, by automatically composing
services, their capabilities can be extended at runtime, therefore theoretically an unlimited
number of new services can be created from an existing set of components, thus making
applications no longer restricted to the original set of operations specified and envisioned
at the design time.
Initial web service efforts failed to hold the promise for providing generic mechanisms
that support discovering, composing, evaluating, executing and monitoring web services
in dynamic environments, especially with the issues raised by the development of new
technologies such as Cloud Computing, Internet of Things and Cyber Physical Systems.
Semantic technologies provide the tools to address various challenges related to the web
services technology, particularly those to be performed in the dynamic mode. However, in
order to realize this potential, significant hurdles still have to be overcome. To deal with
these hurdles, an improvement of the process of service composition becomes necessary,
especially a higher degree of autonomy. Following this direction, service composition has
to proceed autonomously, which on the one hand side reduce human involvement to a
minimum, but on the other side require certain capabilities on the part of the mechanisms
that will support it.
This research considers the Web service composition problem from the viewpoint of
teamwork and addresses the challenge of developing teamwork services, i.e. autonomously
composite services capable of exhibiting teamwork behavior. A service capable of exhibiting
teamwork behavior is one that can effectively cooperate with multiple potential teammates
on a set of collaborative tasks to achieve the overall team goal. Firstly, we lay down the foundations and describe the interaction of services by exploiting the role Model
theory. The description of services with roles and behaviors act as mediator between the
different Web service languages and a formal description that will enable the reasoning
over new paths of collaboration for composition purposes. Then, we benefit from the
teamwork theory, which has spanned diverse disciplines from business management to
cognitive science, human discourse, and distributed artificial intelligence and contribute
by determining the dominant teamwork roles that prevail during service group cooperation.
Novel service teamwork roles are developed and the role modeling approach is extended
to enable web services to automatically cooperate by enhancing service’s interoperability.
These roles aim to (i) enable services to manipulate the uncertainties by being proactive
during their participation in specific events, (ii) capture potential emergent behavior
that happens in the domain during service design and execution, (iii) arrest and handle
any misbehaving of other participants that occurs in the domain, (iv) act as the glue
needed to reconfigure and combine services appropriately in dynamic and unpredictable
environments.
The teamwork role model becomes especially important in dynamic environments since
it enables the development of more efficient composite services, which are stable teams of
services such that their components-members promote better understanding and are able
to cooperate effectively to achieve their objectives. Their teamwork behavior help them
to manipulate the uncertainties by enabling proactiveness during their participation and
by capturing emergent behavior during the process of composition, in which services may
have neither complete nor correct view about their world or other services, that not only
have changeable actions and goals but they are also subject to failure from external events.
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