3 research outputs found
Relational Model for Parameter Description in Automatic Semantic Web Service Composition
Automatic Service Composition is a research direction aimed at facilitating
the usage of atomic web services. Particularly, the goal is to build workflows
of services that solve specific queries, which cannot be resolved by any single
service from a known repository. Each of these services is described
independently by their providers that can have no interaction with each other,
therefore some common standards have been developed, such as WSDL, BPEL, OWL-S.
Our proposal is to use such standards together with JSON-LD to model a next
level of semantics, mainly based on binary relations between parameters of
services. Services relate to a public ontology to describe their functionality.
Binary relations can be specified between input and/or output parameters in
service definition. The ontology includes some relations and inference rules
that help to deduce new relations between parameters of services. To our
knowledge, it is for the first time that parameters are matched not only based
on their type, but on a more meaningful semantic context considering such type
of relations. This enables the automation of a large part of the reasoning that
a human person would do when manually building a composition. Moreover, the
proposed model and the composition algorithm can work with multiple objects of
the same type, a fundamental feature that was not possible before. We believe
that the poor model expressiveness is what is keeping service composition from
reaching large-scale application in practice.Comment: International Conference on Knowledge-Based and Intelligent
Information & Engineering Systems 10 pages, 4 figure
Extending the Service Composition Formalism with Relational Parameters
Web Service Composition deals with the (re)use of Web Services to provide
complex functionality, inexistent in any single service. Over the
state-of-the-art, we introduce a new type of modeling, based on ontologies and
relations between objects, which allows us to extend the expressiveness of
problems that can be solved automatically.Comment: 5 page
Automatic Web Service Composition -- Models, Complexity and Applications
The automatic composition of web services refers to how services can be used
in a complex and aggregate manner, to serve a specific and known functionality.
Given a list of services described by the input and output parameters, and a
request of a similar structure: the initially known and required parameters; a
solution can be designed to automatically search for the set of web services
that satisfy the request, under certain constraints. We first propose two very
efficient algorithms that solve the problem of the automatic composition of the
web services as it was formulated in the competitions organized in 2005 and
2008. The algorithms obtain much better results than the rest of the
participants with respect to execution time and even composition size.
Evaluation consists of running the previous and the proposed solutions on given
benchmarks and generated tests. Further, we design two new models to match
service's parameters, extending the semantic expressiveness of the 2008
challenge. The initial goal is to resolve some simple and practical use-cases
that cannot be expressed in the previous models. We also adhere to modern
service description languages, like OpenAPI and especially schema.org.
Algorithms for the new models can solve instances of significant size.
Addressing a wider and more realistic perspective, we define the online version
of the composition problem. In this regard, we consider that web services and
compositions requests can be added and removed in real-time, and the system
must handle such operations on the fly. It is necessary to maintain the
workflows for users who actively run the compositions over time. As for the new
semantic models, we propose new algorithms and provide comprehensive evaluation
by generating test cases that simulate all corner cases.Comment: 135 pages, PhD Thesis, Alexandru Ioan Cuza University of Iasi (Apr
2020