Connectors meet Choreographies

We present Cho-Reo-graphies (CR), a new language model that unites two powerful programming paradigms for concurrent software based on communicating processes: Choreographic Programming and Exogenous Coordination. In CR, programmers specify the desired communications among processes using a choreography, and define how communications should be concretely animated by connectors given as constraint automata (e.g., synchronous barriers and asynchronous multi-casts). CR is the first choreography calculus where different communication semantics (determined by connectors) can be freely mixed; since connectors are user-defined, CR also supports many communication semantics that were previously unavailable for choreographies. We develop a static analysis that guarantees that a choreography in CR and its user-defined connectors are compatible, define a compiler from choreographies to a process calculus based on connectors, and prove that compatibility guarantees deadlock-freedom of the compiled process implementations

Relating BIP and Reo

Coordination languages simplify design and development of concurrent systems. Particularly, exogenous coordination languages, like BIP and Reo, enable system designers to express the interactions among components in a system explicitly. In this paper we establish a formal relation between BI(P) (i.e., BIP without the priority layer) and Reo, by defining transformations between their semantic models. We show that these transformations preserve all properties expressible in a common semantics. This formal relation comprises the basis for a solid comparison and consolidation of the fundamental coordination concepts behind these two languages. Moreover, this basis offers translations that enable users of either language to benefit from the toolchains of the other.Comment: In Proceedings ICE 2015, arXiv:1508.0459

Treo: Textual Syntax for Reo Connectors

Reo is an interaction-centric model of concurrency for compositional specification of communication and coordination protocols. Formal verification tools exist to ensure correctness and compliance of protocols specified in Reo, which can readily be (re)used in different applications, or composed into more complex protocols. Recent benchmarks show that compiling such high-level Reo specifications produces executable code that can compete with or even beat the performance of hand-crafted programs written in languages such as C or Java using conventional concurrency constructs. The original declarative graphical syntax of Reo does not support intuitive constructs for parameter passing, iteration, recursion, or conditional specification. This shortcoming hinders Reo's uptake in large-scale practical applications. Although a number of Reo-inspired syntax alternatives have appeared in the past, none of them follows the primary design principles of Reo: a) declarative specification; b) all channel types and their sorts are user-defined; and c) channels compose via shared nodes. In this paper, we offer a textual syntax for Reo that respects these principles and supports flexible parameter passing, iteration, recursion, and conditional specification. In on-going work, we use this textual syntax to compile Reo into target languages such as Java, Promela, and Maude.Comment: In Proceedings MeTRiD 2018, arXiv:1806.0933

Modeling Role-Based Systems with Exogenous Coordination

The concept of roles is a promising approach to cope with context dependency and adaptivity of modern software systems. While roles have been investigated in conceptual modeling, programming languages and multi-agent systems, they have been given little consideration within component-based systems. In this paper, we propose a hierarchical role-based approach for modeling relationships and collaborations between components. In particular, we consider the channel-based, exogenous coordination language Reo and discuss possible realizations of roles and related concepts. The static requirements on the binding of roles are modeled by rule sets expressed in many-sorted second-order logic and annotations on the Reo networks for role binding, context and collaborations, while Reo connectors are used to model the coordination of runtime role playing. The ideas presented in this paper may serve as a basis for the formalization and formal analysis of role-based software systems

Incremental composition process for the construction of component-based management

Cyber-physical systems (CPS) are composed of software and hardware components. Many such systems (e.g., IoT based systems) are created by composing existing systems together. Some of these systems are of critical nature, e.g., emergency or disaster management systems. In general, component-based development (CBD) is a useful approach for constructing systems by composing pre-built and tested components. However, for critical systems, a development method must provide ways to verify the partial system at different stages of the construction process. In this paper, for system architectures, we propose two styles: rigid architecture and flexible architecture. A system architecture composed of independent components by coordinating exogenous connectors is in flexible architecture style category. For CBD of critical systems, we select EX-MAN from flexible architecture style category. Moreover, we define incremental composition mechanism for this model to construct critical systems from a set of system requirements. Incremental composition is defined to offer preservation of system behaviour and correctness of partial architecture at each incremental step. To evaluate our proposed approach, a case study of weather monitoring system (part of a disaster management) system was built using our EX-MAN tool

Highly analysable, reusable, and realisable architectural designs with XCD

Connector-Centric Design (XcD) is a new approach to specifying software architectures. XcD views complex connectors as highly significant in architectural designs, as it is the complex connectors that non-functional quality properties in systems can emanate from. So, XcD promotes in designs a clean separation of connectors (interaction behaviours) from components (functional behaviours). Designers can then specify connectors in detail explicitly thus easing the analysis of system designs for quality properties. Furthermore, XcD separates control behaviour from connectors as control strategies. Architectural designs in XcD thus become highly modular with re-usable components, connectors, and control strategies (representing design solutions for quality properties). The end result is the eased architectural experimentation with different design solutions by re-using components/connectors and formal analysis of these solutions to find out the optimal ones

Coordination of Dynamic Software Components with JavaBIP

JavaBIP allows the coordination of software components by clearly separating the functional and coordination aspects of the system behavior. JavaBIP implements the principles of the BIP component framework rooted in rigorous operational semantics. Recent work both on BIP and JavaBIP allows the coordination of static components defined prior to system deployment, i.e., the architecture of the coordinated system is fixed in terms of its component instances. Nevertheless, modern systems, often make use of components that can register and deregister dynamically during system execution. In this paper, we present an extension of JavaBIP that can handle this type of dynamicity. We use first-order interaction logic to define synchronization constraints based on component types. Additionally, we use directed graphs with edge coloring to model dependencies among components that determine the validity of an online system. We present the software architecture of our implementation, provide and discuss performance evaluation results.Comment: Technical report that accompanies the paper accepted at the 14th International Conference on Formal Aspects of Component Softwar

Mediator Connector for Composing Loosely Coupled Software Components

Component-Based Software Development (CBSD) is an approach that has many benefits, such as improving application developer productivity, reducing costs and complexity by reusing of existing codes. Programming within this approach is like assembly (i.e. composing software out of prefabricated components) rather than development, which reduces skill requirements, and allows expertise focuses on domain problems. The foundation of any CBSD methodology is its underlying component model, which defines what components are, how they can be constructed, and specifies the standards and conventions that are needed to enable composition of independently developed component. The current component models do not support composition in both design and deployment phase. They also focus on the specification and packaging of components but provide almost no support for the easy composition of components. Component in these models uses either direct or indirect message passing as connection schemes, which leads to tightly coupling (i.e. components mix computation with control). It is conclude that this research has proposed an effective way for component composition which provides loosely coupling between composed components. For system maintenance and evolution, this decoupling should make it simpler to manage changes in the components, and also changes in the connector separately. This research has resulted in the proposed of mediator connector which is similar to a communication hub. It initiates method calls and manages the returns, and also provides total loosely coupling between components and also itself. Mediator connector is a framework and can be reused without any modification. The components composition using mediator connector belongs to the deployment phase. Our approach is based on interactions between components as a subset of behavior in a system. In order to minimize coupling between components and mediator connector, we have designed and developed an XML-based language, called Component Interaction Markup Language (CIML), where components as well as their interactions are described in a CIML document which are used by mediator connector. For evaluation of mediator connector in order to measure the loosely coupling it provides, four case studies have been tested. To measure coupling we applied Coupling Between Object (CBO) software metric. The result shows that mediator connector provides totally loosely coupling between software components composing in the deployment phase