Reconfiguration of Reo Connectors Triggered by Dataflow

Reo is a language for coordinating autonomous components in distributed environments. Coordination in Reo is performed by circuit-like connectors, which are constructed from primitive, mobile channels with well-defined behaviour. While the structure of a connector can be modeled as a graph, its behaviour is compositionally defined using that of its primitive constituents. In previous work, we showed that graph transformation techniques are well-suited to model reconfigurations of connectors. In this paper, we investigate how the connector colouring semantics can be used to perform dynamic reconfigurations. Dynamic reconfigurations are triggered by dataflow in the connector at runtime, when certain structural patterns enriched with dataflow annotations occur. For instance we are able to elegantly model dynamic Reo circuits, such as just-in-time augmentation of single-b

Reconfiguration of Reo Connectors Triggered by Dataflow

Reo is a language for coordinating autonomous components in distributed environments. Coordination in Reo is performed by circuit-like connectors, which are constructed from primitive, mobile channels with well-defined behaviour. While the structure of a connector can be modeled as a graph, its behaviour is compositionally defined using that of its primitive constituents. In previous work, we showed that graph transformation techniques are well-suited to model reconfigurations of connectors. In this paper, we investigate how the connector colouring semantics can be used to perform dynamic reconfigurations. Dynamic reconfigurations are triggered by dataflow in the connector at runtime, when certain structural patterns enriched with dataflow annotations occur. For instance we are able to elegantly model dynamic Reo circuits, such as just-in-time augmentation of single-buffered channels to a circuit that models a channel with an unbounded buffer. Additionally we extend Reo's visual notation and the Reo animation language to describe and animate dynamically reconfiguring connectors

Decentralised Evaluation of Temporal Patterns over Component-based Systems at Runtime

Long version of the paper accepted for FACS 2014 - The 11th International Symposium on Formal Aspects of Component SoftwareInternational audienceSelf-adaptation allows systems to modify their structure and/or their behaviour depending on the environment and the system itself. Since reconfigurations must not happen at any but in suitable circumstances, guiding and controlling dynamic reconfigurations at runtime is an important issue. This paper contributes to two essential topics of the self-adaptation---a runtime temporal properties evaluation, and a decentralization of control loopsSelf-adaptation allows systems to modify their structure and/or their behaviour depending on the environment and the system itself. Since reconfigurations must not happen at any but in suitable circumstances, guiding and controlling dynamic reconfigurations at runtime is an important issue. This paper contributes to two essential topics of the self-adaptation - a runtime temporal properties evaluation, and a decentralization of control loops. It extends the work on the adaptation of component-based systems at runtime via policies with temporal patterns by providing a) a specific progressive semantics of temporal patterns and b) a decentralised method which is suitable to deal with temporal patterns of component-based systems at runtime

Reachability Analysis on Timed Graph Transformation Systems

In recent years, software increasingly exhibits self-* properties like selfoptimization or self-healing. Such properties require reconfiguration at runtime in order to react to changing environments or detected defects. A reconfiguration might add or delete components as well as it might change the communication topology of the system. Considering communication protocols between an arbitrary number of participants, reconfiguration and state-based protocol behavior are no longer independent from each other and need to be verified based on a common formalism. Additionally, such protocols often contain timing constraints to model real-time properties. These are of integral importance for the safety of the modeled system and thus need to be considered during the verification of the protocol. In current approaches either reconfigurations or timing constraints are not considered. Existing approaches for the verification of timed graph transformation systems lack important constructs needed for the verification of state-based real-time protocol behaviors. As a first step towards a solution to this problem, we introduced Timed Story Driven Modeling [HHH10] as a common formalism integrating state-based real-time protocol behaviors and system reconfigurations based on graph transformations. In this paper, we introduce a framework allowing to perform reachability analysis based on Timed Story Driven Modeling. The framework allows to compute the reachable timed graph transition system based on an initial graph and a set of timed transformation and invariant rules

Putting Teeth into Open Architectures: Infrastructure for Reducing the Need for Retesting

Proceedings Paper (for Acquisition Research Program)The Navy is currently implementing the open-architecture framework for developing joint interoperable systems that adapt and exploit open-system design principles and architectures. This raises concerns about how to practically achieve dependability in software-intensive systems with many possible configurations when: 1) the actual configuration of the system is subject to frequent and possibly rapid change, and 2) the environment of typical reusable subsystems is variable and unpredictable. Our preliminary investigations indicate that current methods for achieving dependability in open architectures are insufficient. Conventional methods for testing are suited for stovepipe systems and depend strongly on the assumptions that the environment of a typical system is fixed and known in detail to the quality-assurance team at test and evaluation time. This paper outlines new approaches to quality assurance and testing that are better suited for providing affordable reliability in open architectures, and explains some of the additional technical features that an Open Architecture must have in order to become a Dependable Open Architecture.Naval Postgraduate School Acquisition Research ProgramApproved for public release; distribution is unlimited

Graph Based Verification of Software Evolution Requirements

Due to market demands and changes in the environment, software systems have to evolve. However, the size and complexity of the current software systems make it time consuming to incorporate changes. During our collaboration with the industry, we observed that the developers spend much time on the following evolution problems: designing runtime reconfigurable software, obeying software design constraints while coping with evolution, reusing old software solutions for new evolution problems. This thesis presents 3 processes and tool suits that aid the developers/designers when tackling these problems.\ud The first process and tool set allow early verification of runtime reconfiguration requirements. In this process the UML models are converted into a graph-based model. The execution semantics of UML are modeled by graph transformation rules. Using these graph transformation rules, the execution of the UML models is simulated. The simulation generates a state-space showing all possible reconfigurations. The runtime reconfiguration requirements are expressed by computational tree logic or with a visual state-based language, which are verified over the generated state-space. When the verification fails a feedback on the problem is provided.\ud The second process and tool set are developed for computer aided detection of static program constraint violations. We developed a modeling language called Source Code Modeling Language (SCML) in which program elements from the source code can be represented. In the proposed process for constraint violation detection, the source code is converted into SCML models. The constraint detection is realized by graph transformation rules. The rules detect the violation and extract information from the SCML model to provide feedback on the location of the problem.\ud The third process and tool set provide computer aided verification of whether a design idiom can be used to implement a change request. The developers tend to implement evolution requests using software structures that are familiar to them; called design idioms. Graph transformations are used for detecting whether the constraints of the design idiom are satisfied or not. For a given design idiom and given source files in SCML, the implementation of the idiom is simulated. If the simulation succeeds, then the models are converted to source code.\u

Towards Guided Trajectory Exploration of Graph Transformation Systems

Graph transformation systems (GTS) are often used for modeling the behavior of complex systems. A common GTS analysis scenario is the exploration of its state space from an initial state to a state adhering to given goals through a proper trajectory. Guided trajectory exploration uses information from some more abstract analysis of the system as hints to reduce the traversed state space. These hints are used to order possible further transitions from a given state (selection) and detect violations early (cut-off), thus pruning unpromising trajectories from the state space. In the current paper, we define cut-off and selection criteria for guiding the trajectory exploration, and use Petri Net analysis results and the dependency relations between rules as hints in our criteria calculation algorithm. The criteria definitions include navigation along dependency relations, various types of ordering for selection and quantifiers for cut-off criteria. Our approach is exemplified on a cloud infrastructure configuration problem