Logical Foundations of Services

In this paper we consider a logical system of networks of processes that interact in an asynchronous manner by exchanging messages through communication channels. This provides a foundational algebraic framework for service-oriented computing that constitutes a primary factor in defining logical specifications of services, the way models of these specifications capture service orchestrations, and how properties of interaction-points, i.e. points through which such networks connect to one another, can be expressed. We formalise the resulting logic as a parameterised institution, which promotes the development of both declarative and operational semantics of services in a heterogeneous setting by means of logic-programming concepts

A graph-semantics of business configurations

In this paper we give graph-semantics to a fundamental part of the semantics of the service modeling language SRML. To achieve this goal we develop a new graph transformation system for what we call 2-level symbolic graphs. These kind of graphs extend symbolic graphs with a simple 2-level hierarchy that can be generalized to arbitrary hierarchies. We formalize the semantics using this new graph transformation system using a simple example of a trip booking agent.Postprint (published version

Exploring Maintainability Assurance Research for Service- and Microservice-Based Systems: Directions and Differences

To ensure sustainable software maintenance and evolution, a diverse set of activities and concepts like metrics, change impact analysis, or antipattern detection can be used. Special maintainability assurance techniques have been proposed for service- and microservice-based systems, but it is difficult to get a comprehensive overview of this publication landscape. We therefore conducted a systematic literature review (SLR) to collect and categorize maintainability assurance approaches for service-oriented architecture (SOA) and microservices. Our search strategy led to the selection of 223 primary studies from 2007 to 2018 which we categorized with a threefold taxonomy: a) architectural (SOA, microservices, both), b) methodical (method or contribution of the study), and c) thematic (maintainability assurance subfield). We discuss the distribution among these categories and present different research directions as well as exemplary studies per thematic category. The primary finding of our SLR is that, while very few approaches have been suggested for microservices so far (24 of 223, ?11%), we identified several thematic categories where existing SOA techniques could be adapted for the maintainability assurance of microservices

A Dynamic Reconfiguration Model of Web Services in Service-Oriented Architecture

Service-Oriented Architecture (SOA) makes it possible to build distributed systems with web services that can be looked up, published and bound on the execution time across the boundary of an organisation over the Internet. By using standard interfaces and message-exchanging protocols, developers are able to reuse existing web services and integrate these individual services. Nevertheless, SOA must be able to provide a way to cope with dynamic changes that may occur in the system requirements and the environment in which the system operates. The means is known as dynamic reconfiguration that allows web services binding happens at runtime by matching the functional as well as Quality of Service (QoS) requirements to ensure dependable SOA systems. In the paper, we introduce a dynamic reconfiguration of web services model (DREWS) using middleware-based approach. The model intended to handle functional and QoS requirements during dynamic reconfiguration process and to provide an explicit mechanism during pre-, in-, and post-adaptation stages. A selfadaptive tool is developed based on the model to support the dynamic reconfiguration process that allows minimum human intervention

A Model of Emotion as Patterned Metacontrol

Adaptive agents use feedback as a key strategy to cope with un- certainty and change in their environments. The information fed back from the sensorimotor loop into the control subsystem can be used to change four different elements of the controller: parameters associated to the control model, the control model itself, the functional organization of the agent and the functional realization of the agent. There are many change alternatives and hence the complexity of the agent’s space of potential configurations is daunting. The only viable alternative for space- and time-constrained agents —in practical, economical, evolutionary terms— is to achieve a reduction of the dimensionality of this configuration space. Emotions play a critical role in this reduction. The reduction is achieved by func- tionalization, interface minimization and by patterning, i.e. by selection among a predefined set of organizational configurations. This analysis lets us state how autonomy emerges from the integration of cognitive, emotional and autonomic systems in strict functional terms: autonomy is achieved by the closure of functional dependency. Emotion-based morphofunctional systems are able to exhibit complex adaptation patterns at a reduced cognitive cost. In this article we show a general model of how emotion supports functional adaptation and how the emotional biological systems operate following this theoretical model. We will also show how this model is also of applicability to the construction of a wide spectrum of artificial systems1

Towards Consistency Management for a Business-Driven Development of SOA

International audienceThe usage of the Service Oriented Architecture (SOA) along with the Business Process Management has emerged as a valuable solution for the complex (business process driven) system engineering. With a Model Driven Engineering where the business process models drive the supporting service component architectures, less effort is gone into the Business/IT alignment during the initial development activities, and the IT developers can rapidly proceed with the SOA implementation. However, the difference between the design principles of the emerging domain-specific languages imposes serious challenges in the following re-design phases. Moreover, enabling evolutions on the business process models while keeping them synchronized with the underlying software architecture models is of high relevance to the key elements of any Business Driven Development (BDD). Given a business process update, this paper introduces an incremental model transformation approach that propagates this update to the related service component configurations. It, therefore, supports the change propagation among heterogenous domain-specific languages, e.g., the BPMN and the SCA. As a major contribution, our approach makes model transformation more tractable to reconfigure system architecture without disrupting its structural consistency. We propose a synchronizer that provides the BPMN-to-SCA model synchronization with the help of the conditional graph rewriting

A graph-based design framework for services

Service-oriented systems rely on software applications that offer services through the orchestration of activities performed by external services procured on the fly when they are needed. This paper presents an overview of a graph-based framework developed around the notions of service and activity module for supporting the design of service-oriented systems in a way that is independent of execution languages and deployment platforms. The framework supports both behaviour and quality-of-service constraints for the discovery, ranking and selection of external services. Service instantiation and binding are captured as algebraic operations on configuration graphs. © 2012 Springer-Verlag

On Activation, Connection, and Behavior in Dynamic Architectures

The architecture of a system describes the system’s overall organization into components and connections between those components. With the emergence of mobile computing, dynamic architectures became increasingly important. In such architectures, components may appear or disappear, and connections may change over time. Despite the growing importance of dynamic architectures, the specification of properties for those architectures remains a challenge. To address this problem, we introduce the notion of configuration traces to model properties of dynamic architectures. Then, we characterize activation, connection, and behavior properties as special sets of configuration traces. We then show soundness and relative completeness of our characterization, i.e., we show that the intersection of an activation, connection, and behavior property contains all relevant configuration traces and that (almost) every property can be separated into these classes. Configuration traces can be used to specify general properties of dynamic architectures and the separation into different classes provides a systematic way for their specification. To evaluate our approach we apply it to the specification and verification of the Blackboard architecture pattern