Injecting continuous time execution into service-oriented computing

Service-Oriented Computing is a computing paradigm that utilizes services as fundamental elements to support rapid, low-cost development of distributed applications in heterogeneous environments. In Service-Oriented Computing, a service is defined as an independent and autonomous piece of functionality which can be described, published, discovered and used in a uniform way. SENSORIA Reference Modeling Language is developed in the IST-FET integrated project. It provides a formal abstraction for services at the business level. Hybrid systems arise in embedded control when components that perform discrete changes are coupled with components that perform continuous processes. Normally, the discrete changes can be modeled by finite-state machines and the continuous processes can be modeled by differential equations. In an abstract point of view, hybrid systems are mixtures of continuous dynamics and discrete events. Hybrid systems are studied in different research areas. In the computer science area, a hybrid system is modeled as a discrete computer program interacting with an analog environment. In this thesis, we inject continuous time execution into Service-Oriented Computing by giving a formal abstraction for hybrid systems at the business level in a Service-Oriented point of view, and develop a method for formal verifications. In order to achieve the first part of this goal, we make a hybrid extension of Service-Oriented Doubly Labeled Transition Systems, named with Service-Oriented Hybrid Doubly Labeled Transition Systems, make an extension of the SENSORIA Reference Modeling Language and interpret it over Service-Oriented Hybrid Doubly Labeled Transition Systems. To achieve the second part of this goal, we adopt Temporal Dynamic Logic formulas and a set of sequent calculus rules for verifying the formulas, and develop a method for transforming the SENSORIA Reference Modeling Language specification of a certain service module into the respective Temporal Dynamic Logic formulas that could be verified. Moreover, we provide a case study of a simplified small part of the European Train Control System which is specified and verified with the approach introduced above. We also provide an approach of implementing the case study model with the IBM Websphere Process Server, which is a comprehensive Service-Oriented Architecture integration platform and provides support for the Service Component Architecture programming model. In order to realize this approach, we also provide functions that map models specified with the SENSORIA Reference Modeling Language to Websphere Process Server applications

State of runtime adaptation in service-oriented systems:what, where, when, how and right

Software as a Service reflects a ‘service-oriented’ approach to software development that is based on the notion of composing applications by discovering and invoking network-available services to accomplish some task. However, as more business organisations adopt service-oriented solutions and the demands on them grow, the problem of ensuring that the software systems can adapt fast and effectively to changing business needs, changes in their runtime environment and failures in provided services has become an increasingly important research problem. Dynamic adaptation has been proposed as a way to address the problem. However, for adaptation to be effective several other factors need to be considered. This study identifies the key factors that influence runtime adaptation in service-oriented systems (SOSs) and examines how well they are addressed in 29 adaptation approaches intended to support SOSs

A self-learning framework for validation of runtime adaptation in service-oriented systems

Ensuring that service-oriented systems can adapt quickly and effectively to changes in service quality, business needs and their runtime environment is an increasingly important research problem. However, while considerable research has focused on developing runtime adaptation frameworks for service-oriented systems, there has been little work on assessing how effective the adaptations are. Effective adaptation ensures the system remains relevant in a changing environment. One way to address the problem is through validation. Validation allows us to assess how well a recommended adaptation addresses the concerns for which the system is reconfigured and provides us with insights into the nature of problems for which different adaptations are suited. However, the dynamic nature of runtime adaptation and the changeable contexts in which service-oriented systems operate make it difficult to specify appropriate validation mechanisms in advance. This thesis describes a novel consumer-centred approach that uses machine learning to continuously validate and refine runtime adaptation in service-oriented systems, through model-based clustering and deep learning. To evaluate the efficacy of the approach a medium sized health care case study was devised and implemented. The results obtained show that self-validation significantly improves the dynamic adaptation process by autonomously addressing changing user requirements at runtime. Further work in this area can improve the framework by integrating other learning algorithms as well as testing the framework on a larger case study

A formal model for service-oriented interactions

In this paper, we provide a mathematical semantics for a fragment of a languageSRMLthat we have defined in the IST-FET-GC2 Integrated Project SENSORIA for modelling service-oriented systems. The main goal of this research is to make available a foundational basis for the development of practical modelling languages and tools that designers can use to model complex services at a level of abstraction that captures business functionality independently of the languages in which services are implemented and the platforms in which they execute. The basic artefact of the language is the service module, which provides a model for a complex service in terms of a number of components that jointly orchestrate a business function and may dynamically discover and bind to external parties that can deliver required functionalities. We define a mathematical model of computation and an associated logic for service-oriented systems based on the typical business conversations that occur between the parties that deliver a service. We then define the semantics of SRML service modules over this model and logic, and formulate a property of correctness that guarantees that services programmed and assembled as specified in a module provide the business functionality advertised by that module. Finally, we define an algebraic operation of composition of service modules that preserves correctness. To the best of our knowledge, there is no other formal approach that has been defined from first principles with the aim of capturing the business nature of service conversations and support service assembly based on the business logic that is required, not as it is programmed. © 2012 Elsevier B.V. All rights reserved