Simon Giesecke

Ontology-based modelling of architectural styles

The conceptual modelling of software architectures is of central importance for the quality of a software system. A rich modelling language is required to integrate the different aspects of architecture modelling, such as architectural styles, structural and behavioural modelling, into a coherent framework. Architectural styles are often neglected in software architectures. We propose an ontological approach for architectural style modelling based on description logic as an abstract, meta-level modelling instrument. We introduce a framework for style definition and style combination. The application of the ontological framework in the form of an integration into existing architectural description notations is illustrated.

An ontology-based approach for modelling architectural styles

The conceptual modelling of software architectures is of central importance for the quality of a software system. A rich modelling language is required to integrate the different aspects of architecture modelling, such as architectural styles, structural and behavioural modelling, into a coherent framework. We propose an ontological approach for architectural style modelling based on description logic as an abstract, meta-level modelling instrument. Architectural styles are often neglected in software architectures. We introduce a framework for style definition and style combination. The link between quality requirements and conceptual modelling of architectural styles is investigated. The application of the ontological framework in the form of an integration into existing architectural description notations such as ACME and UML-based approaches, and also service ontologies is illustrated.

Trustworthy software systems: a discussion of basic concepts and terminology

Basic concepts and terminology for trustworthy software systems are discussed. Our discussion of definitions for terms in the domain of trustworthy software systems is based on former achievements in dependable, trustworthy and survivable systems. We base our discussion on the established literature and on approved standards. These concepts are discussed in the context of our graduate school TrustSoft on trustworthy software systems. In TrustSoft, we consider trustworthiness of software systems as determined by correctness, safety, quality of service (performance, reliability, availability), security, and privacy. Particular means to achieve trustworthiness of component-based software systems - as investigated in TrustSoft - are formal verification, quality prediction and certification; complemented by fault diagnosis and fault tolerance for increased robustness.

Classifying architectural constraints as a basis for software quality assessment

Architectural styles and patterns have been studied since the inception of software architecture as a discipline. We generalise architectural styles, patterns and similar concepts by introducing the notion of architectural constraints. An architectural constraint is a vehicle for the reuse of architectural design knowledge and for the improvement of software quality. It may be used for improving architectural analyses of quality characteristics of the software system to be realised. We present the method for surveying the literature on architectural constraint concepts, and provide a taxonomy covering various definitions of architectural styles and patterns.

Middleware-Induced Architectural Style Modelling for Architecture Exploration

The MID ARCH method is a software design method for exploring software architecture alternatives that use different middleware platforms. First, candidate architectures are modelled based on different architectural styles that are induced by the respective middleware platforms. Candidate styles are chosen using a taxonomy of such styles. The goal is the evaluation of candidate architectures with respect to a goal/question/metric quality model. We illustrate the modelling approach using the Apache Cocoon Web component framework and related technologies, and a taxonomy of their associated styles.

Comparative evaluation of dependability characteristics for peer-to-peer architectural styles by simulation ☆

An important concern for the successful deployment of a dependable system is its quality of service (QoS), which is significantly influenced by its architectural style. We propose the comparative evaluation of architectural styles by simulation. Our approach integrates architectural styles and concrete architectures to enable early design-space exploration in order to predict the QoS of peer-to-peer systems. We illustrate the approach via two case studies where availability of resources and performance of peer-to-peer search methods are evaluated. Based on our experience with these simulation environments, we sketch tool support for simulating architectural changes at runtime.

Trace-Context Sensitive Performance Profiling for Enterprise Software Applications

Software response time distributions can be of high variance and multi-modal. Such characteristics reduce confidence or applicability in various statistical evaluations. We contribute an approach to correlating response times to their corresponding operation execution sequence. This provides calling-context sensitive timing behavior models. The approach is based on three equivalence relations: caller-context, stack-context, and trace-context equivalence. To prevent model size explosion, a tree-based hierarchy provides timing behavior models that provide a trade-off between timing behavior model size and the amount of calling-context information considered. In the case study, our approach provides response time distributions with significantly lower standard deviation, compared to using less or no calling-context information. An example from a performance analysis of an industry system demonstrates that multi-modal distributions can be replaced by multiple unimodal distributions using trace-context analysis.

Availability simulation of peer-to-peer architectural styles

This paper addresses the issue of quantitatively investigating availability within peer-to-peer systems. We devise a conceptual framework integrating architectural styles, architectures, and concrete systems. We identify basic characteristics of architectural styles for peer-to-peer systems and give a formal model to describe derived architectures. Architectural descriptions are used as input for simulations to predict the availability of services within real-world systems.

Towards a modular and scalable architecture for high-level smart grid applications

Sensor and actor population within future smart distribution grids is much denser than within transmission grids. Thereby, future grid management systems have to cope with larger amounts of data than todays grid management systems. Also, future high-level applications for network management must be suited for use within automatic control loops. This results in new challenges for designing high-level application components for power grid management. This paper addresses related software engineering challenges and presents solutions for designing software within the context of grid management.