Mohammad Alhaj

Towards advanced goal model analysis with jUCMNav

Goal modeling is an important part of various types of activities such as requirements engineering, business management, and compliance assessment. The Goal-oriented Requirement Language is a standard and mature goal modeling language supported by the jUCMNav tool. However, recent applications of GRL to a regulatory context highlighted several analysis issues and limitations whose resolutions are urgent, and also likely applicable to other languages and tools. This paper investigates issues related to the computation of strategy and model differences, the management of complexity and uncertainty, sensitivity analysis, and various domain-specific considerations. For each, a solution is proposed, implemented in jUCMNav, and illustrated through simple examples. These solutions greatly increase the analysis capabilities of GRL and jUCMNav in order to handle real problems.

Transformation challenges: from software models to performance models

A software model can be analysed for non-functional requirements by extending it with suitable annotations and transforming it into analysis models for the corresponding non-functional properties. For quantitative performance evaluation, suitable annotations are standardized in the “UML Profile for Modeling and Analysis of Real-Time Embedded systems” (MARTE) and its predecessor, the “UML Profile for Schedulability, Performance and Time”. A range of different performance model types (such as queueing networks, Petri nets, stochastic process algebra) may be used for analysis. In this work, an intermediate “Core Scenario Model” (CSM) is used in the transformation from the source software model to the target performance model. CSM focuses on how the system behaviour uses the system resources. The semantic gap between the software model and the performance model must be bridged by (1) information supplied in the performance annotations, (2) in interpretation of the global behaviour expressed in the CSM and (3) in the process of constructing the performance model. Flexibility is required for specifying sets of alternative cases, for choosing where this bridging information is supplied, and for overriding values. It is also essential to be able to trace the source of values used in a particular performance estimate. The performance model in turn can be used to verify responsiveness and scalability of a software system, to discover architectural limitations at an early stage of development, and to develop efficient performance tests. This paper describes how the semantic gap between software models in UML+MARTE and performance models (based on queueing or Petri nets) can be bridged using transformations based on CSMs, and how the transformation challenges are addressed.

Towards outcome-based regulatory compliance in aviation security

Transport Canada is reviewing its Aviation Security regulations in a multi-year modernization process. As part of this review, consideration is given to transitioning regulations where appropriate from a prescriptive style to an outcome-based style. This raises new technical and cultural challenges related to how to measure compliance. This paper reports on a novel approach used to model regulations with the Goal-oriented Requirement Language, augmented with qualitative indicators. These models are used to guide the generation of questions for inspection activities, enable a flexible conversion of real-world data into goal satisfaction levels, and facilitate compliance analysis. A new propagation mechanism enables the evaluation of the compliance level of an organization. This outcome-based approach is expected to help get a more precise understanding of who complies with what, while highlighting opportunities for improving existing regulatory elements.

Approach for generating performance models from UML models of SOA systems

Model-Driven SOA is an emerging approach for developing service-oriented systems using models at different levels of abstractions and applying model transformations to generate either code or other models for the analysis of non-functional properties, such as performance. The paper proposes an approach for deriving layered queueing performance models for the evaluation of the runtime performance characteristics of such systems in the early development phases, before the entire system is built and can be deployed and measured. Early performance evaluation helps to choose an appropriate architecture, design and configuration alternatives, so that the final system meets its performance requirements. The starting point for derivation is a platform independent UML model of a SOA system representing the workflows, architecture of the underlying components offering services, and behavior of the corresponding runtime scenarios. A platform dependent model, obtained by weaving platform services into the platform-independent model through aspect-oriented modeling techniques, represents the source model for the transformation into a performance model. The deployment of the software on hardware resources is also part of the source model. The UML model is annotated with performance information by using the standard UML profile MARTE. The proposed approach is illustrated with a healthcare application.

Creating Quantitative Goal Models: Governmental Experience

Precision in goal models can be enhanced using quantitative rather than qualitative scales. Selecting appropriate values is however often difficult, especially when groups of stakeholders are involved. This paper identifies and compares generic and domain-specific group decision approaches for selecting quantitative values in goal models. It then reports on the use of two approaches targeting quantitative contributions, actor importance, and indicator definitions in the Goal-oriented Requirement Language. The approaches have been deployed in two independent branches of the Canadian government.

Regulation-Based Dimensional Modeling for Regulatory Intelligence

Regulations are a source of evolving requirements for products and organizations. As regulatory institutions shift towards outcome-based regulations, they increasingly adopt legislation performance modeling, at the basis of regulatory intelligence. In this context, performance modeling refers to the measuring of important business aspects in a coordinated manner and the use of these measurements for improved decision making. Considering that in many cases regulatory texts already exist, it is necessary to build a performance model based on existing regulations that may be still prescriptive rather than outcome-based. The process of turning the underlying textual legislation into a formal performance model that can be assessed by Business Intelligence (BI) tools is complicated due to organizational, cultural, and technological reasons. In this paper, we present a methodology from a technical perspective that enables regulatory institutions to reason about regulations and compliance with regulations as new dimensions. We demonstrate the methodology using traffic law as an example regulation, jUCMNav for performance modeling, and IBM Cognos for BI reporting.

Automatic generation of performance models for SOA systems

The paper proposes a model-driven approach for deriving performance models from UML design models of Service-Oriented Architecture (SOA) enterprise systems, in order to evaluate their run-time performance from the early development phases. This helps to choose between different architecture, design, and configuration alternatives in order to meet the performance requirements. The source model of the proposed transformation is a platform-independent UML model of the service-oriented system. Aspect-oriented modeling techniques are used to produce a platform-dependent model by weaving aspect models of platform operations into the platform-independent model. The platform-dependent model thus obtained represents the source model for the transformation into a performance model. The UML profile MARTE is used to annotate models with performance information. A healthcare example illustrates the proposed approach.

Traceability Links in Model Transformations between Software and Performance Models

In Model Driven Engineering, traceability is used to establish relationships between various software artifacts during the software life cycle. Traceability can be also used to define dependencies between related elements in different models, to propagate and verify properties from one model to another and to analyze the impact of changes. In this paper we describe how to define typed trace-links between different kinds of models in our model transformation chain PUMA4SOA, which generates Layered Queuing performance models from UML software models of service-oriented applications. The goal of PUMA4SOA is to help evaluate the performance of SOA systems in the early development phases. In our approach, the traceability links are stored externally in a new model, which maintain traces separately from the source and target models they refer to. We illustrate how traceability links can be used to propagate the results of the performance model back to the original software model.

Modeling Early Availability Requirements Using Aspect-Oriented Use Case Maps

Non-functional requirements such as availability, reliability, and security are often crucial in designing and implementing distributed real-time systems. As a result, such non-functional requirements should be addressed as early as possible in the system development life-cycle. The widespread interest in dependability modeling and analysis techniques at the requirements elicitation and analysis stage provides the major motivation for this research. This paper presents a novel approach to describe high-level availability requirements using the Aspect-oriented Use Case Maps (AoUCM) language. AoUCM adds aspects-oriented concepts to the Use Case Maps (UCM) language, part of the ITU-T User Requirements Notation (URN) standard. The proposed approach relies on a mapping of availability architectural tactics to reusable AoUCM models, allowing availability tactics to be encapsulated early in the software development life-cylce. Initial tool support for the resulting availability extensions, is provided by the jUCMNav tool. We demonstrate the applicability of our approach using a case study of Lawful Intercept (LI), an IP router feature.

Drafting and modeling of regulations: Is it being done backwards?

The performance modeling of regulations is a relatively recent innovation. However, as regulators in many domains increasingly look to move from prescriptive regulations towards more outcome-based regulations, the use of performance modeling will become more common place. The major difference of outcome-based regulations over prescriptive regulations is that the main interest lies in specifying clear objectives of the regulations and measuring whether regulated parties achieve these objectives, while leaving much freedom to the regulated party on how to meet these objectives. Recently, we have found that the use of performance modeling provides benefits such as revealing inconsistencies and lack of clarity in existing regulatory language. In this paper, we report on these experiences, summarize guidelines for the modeling of regulations, and examine whether the current drafting processes for regulations are optimized to take advantage of these additional benefits. We explore the advantages and disadvantages of various ways of augmenting the current approach with goal-oriented modeling of regulations. Based on our experience with Aviation Security regulations, we believe it is time for modeling to play a new role in helping to guide the drafting of regulations.