Jan Øyvind Aagedal

Model-based risk assessment to improve enterprise security

The main objective of the CORAS project is to provide methods and tools for precise, unambiguous, and efficient risk assessment of security critical systems. To this end, we advocate a model-based approach to risk assessment, and define the required models for this. Whereas traditional risk assessment is performed without any formal description of the target of evaluation or results of the risk assessment, CORAS aims to provide a well defined set of models well suited to (1) describe the target of assessment at the right level of abstraction, (2) as a medium for communication between different groups of stakeholders involved in a risk assessment, and (3) to document risk assessment results and the assumptions on which these results depend. We propose models for each step in a risk assessment process and report results of use.

Toward standardised model to text transformations

The objective of this work is to assess the qualities of the MOFScript language, which has recently been submitted to the OMG as a proposed model to text transformation language. This is done by identifying requirements for this type of language and evaluating the MOFScript language with regard to these. The language is presented along with a tool implementation and compared with the alternative languages submitted to the OMG Model to Text RFP.

Evaluating Quality in Model-Driven Engineering

In model-driven engineering (MDE), models are the prime artifacts, and developing high-quality systems depends on developing high-quality models and performing transformations that preserve quality or even improve it. This paper presents quality goals in MDE and states that the quality of models is affected by the quality of modeling languages, tools, modeling processes, the knowledge and experience of modelers, and the quality assurance techniques applied. The paper further presents related work on these factors and identifies pertinent research challenges. Some quality goals such as well-formedness and precision are especially important in MDE. Research on quality in MDE can promote adoption of MDE for complex system engineering.

ODP enterprise language: UML perspective

Presents extensions and refinements of those concepts that are pertinent to the ODP (open distributed processing) enterprise viewpoint. We first highlight the intricacies of enterprise modelling and then present key enterprise modelling concepts. These concepts represent both refinements to the existing ODP concepts and some new concepts that we propose for the ODP enterprise language standard currently being progressed. We then investigate how the relevant UML (Unified Modelling Language) constructs can be used to represent the enterprise language concepts and to support the enterprise specifications. We conclude by discussing various tools that are needed to facilitate the processes of enterprise modelling, verification and building of open distributed systems.

Modelling QoS: Towards a UML Profile

In this paper, we present a conceptual object model for specifying Quality of Service (QoS) that forms a basis for a UML profile for QoS. The conceptual model is based on CQML, a lexical language for QoS specification.A QoS characteristic represents some aspect of the QoS of a system, service or resource that can be identified and quantified. A QoS statement expresses some QoS by constraining values of QoS characteristics. A QoS relation specifies the mutual obligation of an object and its environment with respect to QoS. These concepts are related to the UML meta-model in order to define a UML profile for QoS. An example from a Lecture on Demand (LoD) case study depicts how these concepts can be used during enterprise modelling and system design.

Construction and execution of adaptable applications using an aspect-oriented and model driven approach

Constructing and executing distributed applications that can adapt to their current operating context, in order to maintain or enhance Quality of Service (QoS) attribute levels, are complex tasks. Managing multiple, interacting QoS features is particularly difficult since these features tend to be distributed across the system and tangled with other features. The crosscutting nature of QoS features can make them difficult to evolve, and it can make it complicated to dynamically optimize with respect to provided QoS during execution. Furthermore, it complicates efficient construction of application variants that differ in their QoS characteristics to suit various execution contexts. This paper presents an aspect-oriented and model driven approach for constructing and a QoS-aware middleware for execution of QoS-sensitive applications. Aspect-oriented modeling techniques are used to separate QoS features from primary application logic, and for efficient specification of alternative application variants. Model driven engineering techniques are used to derive run-time representations of application variants from platform independent models. The developed middleware chooses the best variant according to the current operating context and the available resources.

Quality of Adaptation

In order to support reusable and extendable solutions to self-adaptation, state of the art within adaptive systems include a diversity of architectures and mechanisms targeting different application types, technologies, context and concerns. Current approaches do not allow reasoning about the mechanisms and strategies themselves during startup-time or run-time. Consequently, the configuration or tuning of the adaptation system itself, must be done manually by a user or an administrator, or hard coded at design-time, making it harder to reuse. In this position paper, we propose considering adaptation as a service. In order to allow reasoning about and comparing such services, we define quality of adaptation (QoA) to be the qualitative properties of an adaptation service. We argue that this approach facilitates the development of adaptation mechanisms and control that are, like the system they adapt, reusable and adaptable, and open to evolution

A Framework for QoS-Aware Model Transformation, Using a Pattern-Based Approach

A current trend in software engineering is the changing of software development from being code-centric to become model-centric. This entails many challenges. Traceability between models at different abstraction levels must be managed. Mechanisms for model transformation and code generation must be in place, and these must be able to produce the desired results in terms of derived models and code. A main consideration in this respect is obviously to produce something that provides the expected functionality; another key aspect is to deliver models and code that specify systems that will adhere to the required quality of the provided services. Thus, specification and consideration of quality of service (QoS) when deriving system models are significant. In this paper we describe an approach where QoS aspects are considered when performing model transformations. The approach is pattern-based and uses UML 2.0 [1] as basis for modeling. For specification of QoS, the current submission of the UML profile for modeling QoS [2] is used as the baseline. The transformation specification is aligned with currently available results from the ongoing standardization process of MOF QVT [3][4]. The framework provides mechanisms and techniques for considering QoS throughout a model- driven development process. A key proposal of the approach is to gradually resolve QoS requirements when performing model transformations. The paper also describes a QoS-aware execution platform for resolving QoS requirements at run-time.

Enterprise modelling and QoS for command and control systems

Presents an approach for enterprise modelling of complex command and control systems. This approach is based on the use of ODP enterprise language concepts (communities, roles, enterprise objects, policies and contracts), augmented with enterprise-related quality-of-service (QoS) descriptions. These descriptions are based on the ODP QoS statements, namely QoS capabilities, QoS requirements, QoS offers, QoS contracts and QoS observations. We then present a set of practical guidelines for applying such an extended ODP enterprise viewpoint terminology. The use of these guidelines is illustrated by an example of a command and control system for oil platform disaster operations. We describe the main communities involved, their roles and policies, as well as key QoS statements for these communities. The UML notation is used to represent the concepts described throughout the paper.

DEVELOPING DISTRIBUTED SERVICES USING AN ASPECT ORIENTED MODEL DRIVEN FRAMEWORK

To manage the development of cooperative information systems that support the dynamics and mobility of modern businesses, separation of concern mechanisms and abstractions are needed. Model driven development (MDD) approaches utilize abstraction and transformation to handle complexity. In MDD, specifying transformations between models at various levels of abstraction can be a complex task. Specifying transformations for pervasive system services that are tangled with other system services is particularly difficult because the elements to be transformed are distributed across a model. This paper presents an aspect oriented model driven framework (AOMDF) that facilitates separation of pervasive services and supports their transformation across different levels of abstraction. The framework facilitates composition of pervasive services with enterprise services at various levels of abstraction. The framework is illustrated using an example in which a platform independent model of a banking service is transformed to a platform specific model.