10,972 research outputs found
Tau Be or not Tau Be? - A Perspective on Service Compatibility and Substitutability
One of the main open research issues in Service Oriented Computing is to
propose automated techniques to analyse service interfaces. A first problem,
called compatibility, aims at determining whether a set of services (two in
this paper) can be composed together and interact with each other as expected.
Another related problem is to check the substitutability of one service with
another. These problems are especially difficult when behavioural descriptions
(i.e., message calls and their ordering) are taken into account in service
interfaces. Interfaces should capture as faithfully as possible the service
behaviour to make their automated analysis possible while not exhibiting
implementation details. In this position paper, we choose Labelled Transition
Systems to specify the behavioural part of service interfaces. In particular,
we show that internal behaviours (tau transitions) are necessary in these
transition systems in order to detect subtle errors that may occur when
composing a set of services together. We also show that tau transitions should
be handled differently in the compatibility and substitutability problem: the
former problem requires to check if the compatibility is preserved every time a
tau transition is traversed in one interface, whereas the latter requires a
precise analysis of tau branchings in order to make the substitution preserve
the properties (e.g., a compatibility notion) which were ensured before
replacement.Comment: In Proceedings WCSI 2010, arXiv:1010.233
Analysis and Verification of Service Interaction Protocols - A Brief Survey
Modeling and analysis of interactions among services is a crucial issue in
Service-Oriented Computing. Composing Web services is a complicated task which
requires techniques and tools to verify that the new system will behave
correctly. In this paper, we first overview some formal models proposed in the
literature to describe services. Second, we give a brief survey of verification
techniques that can be used to analyse services and their interaction. Last, we
focus on the realizability and conformance of choreographies.Comment: In Proceedings TAV-WEB 2010, arXiv:1009.330
Higher-Order Process Modeling: Product-Lining, Variability Modeling and Beyond
We present a graphical and dynamic framework for binding and execution of
business) process models. It is tailored to integrate 1) ad hoc processes
modeled graphically, 2) third party services discovered in the (Inter)net, and
3) (dynamically) synthesized process chains that solve situation-specific
tasks, with the synthesis taking place not only at design time, but also at
runtime. Key to our approach is the introduction of type-safe stacked
second-order execution contexts that allow for higher-order process modeling.
Tamed by our underlying strict service-oriented notion of abstraction, this
approach is tailored also to be used by application experts with little
technical knowledge: users can select, modify, construct and then pass
(component) processes during process execution as if they were data. We
illustrate the impact and essence of our framework along a concrete, realistic
(business) process modeling scenario: the development of Springer's
browser-based Online Conference Service (OCS). The most advanced feature of our
new framework allows one to combine online synthesis with the integration of
the synthesized process into the running application. This ability leads to a
particularly flexible way of implementing self-adaption, and to a particularly
concise and powerful way of achieving variability not only at design time, but
also at runtime.Comment: In Proceedings Festschrift for Dave Schmidt, arXiv:1309.455
Cyber-Virtual Systems: Simulation, Validation & Visualization
We describe our ongoing work and view on simulation, validation and
visualization of cyber-physical systems in industrial automation during
development, operation and maintenance. System models may represent an existing
physical part - for example an existing robot installation - and a software
simulated part - for example a possible future extension. We call such systems
cyber-virtual systems.
In this paper, we present the existing VITELab infrastructure for
visualization tasks in industrial automation. The new methodology for
simulation and validation motivated in this paper integrates this
infrastructure. We are targeting scenarios, where industrial sites which may be
in remote locations are modeled and visualized from different sites anywhere in
the world.
Complementing the visualization work, here, we are also concentrating on
software modeling challenges related to cyber-virtual systems and simulation,
testing, validation and verification techniques for them. Software models of
industrial sites require behavioural models of the components of the industrial
sites such as models for tools, robots, workpieces and other machinery as well
as communication and sensor facilities. Furthermore, collaboration between
sites is an important goal of our work.Comment: Preprint, 9th International Conference on Evaluation of Novel
Approaches to Software Engineering (ENASE 2014
Detecting Ontological Conflicts in Protocols between Semantic Web Services
The task of verifying the compatibility between interacting web services has
traditionally been limited to checking the compatibility of the interaction
protocol in terms of message sequences and the type of data being exchanged.
Since web services are developed largely in an uncoordinated way, different
services often use independently developed ontologies for the same domain
instead of adhering to a single ontology as standard. In this work we
investigate the approaches that can be taken by the server to verify the
possibility to reach a state with semantically inconsistent results during the
execution of a protocol with a client, if the client ontology is published.
Often database is used to store the actual data along with the ontologies
instead of storing the actual data as a part of the ontology description. It is
important to observe that at the current state of the database the semantic
conflict state may not be reached even if the verification done by the server
indicates the possibility of reaching a conflict state. A relational algebra
based decision procedure is also developed to incorporate the current state of
the client and the server databases in the overall verification procedure
On Secure Implementation of an IHE XUA-Based Protocol for Authenticating Healthcare Professionals
The importance of the Electronic Health Record (EHR) has been addressed in recent years by governments and institutions.Many large scale projects have been funded with the aim to allow healthcare professionals to consult patients data. Properties such as confidentiality, authentication and authorization are the key for the success for these projects. The Integrating the Healthcare Enterprise (IHE) initiative promotes the coordinated use of established standards for authenticated and secure EHR exchanges among clinics and hospitals. In particular, the IHE integration profile named XUA permits to attest user identities by relying on SAML assertions, i.e. XML documents containing authentication statements. In this paper, we provide a formal model for the secure issuance of such an assertion. We first specify the scenario using the process calculus COWS and then analyse it using the model checker CMC. Our analysis reveals a potential flaw in the XUA profile when using a SAML assertion in an unprotected network. We then suggest a solution for this flaw, and model check and implement this solution to show that it is secure and feasible
Achieving interoperability through semantics-based technologies: the instant messaging case
The success of pervasive computing depends on the ability to compose a multitude of networked applications dynamically in order to achieve user goals. However, applications from different providers are not able to interoperate due to incompatible interaction protocols or disparate data models. Instant messaging is a representative example of the current situation, where various competing applications keep emerging. To enforce interoperability at runtime and in a non-intrusive manner, mediators are used to perform the necessary translations and coordination between the heterogeneous applications. Nevertheless, the design of mediators requires considerable knowledge about each application as well as a substantial development effort. In this paper we present an approach based on ontology reasoning and model checking in order to generate correct-by-construction mediators automatically. We demonstrate the feasibility of our approach through a prototype tool and show that it synthesises mediators that achieve efficient interoperation of instant messaging applications
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