Stephan Poelmans

On the Definition of Service Granularity and Its Architectural Impact

Service granularity generally refers to the size of a service. The fact that services should be large-sized or coarse-grained is often postulated as a fundamental design principle of service oriented architecture (SOA). However, multiple meanings are put on the term granularity and the impact of granularity on architectural qualities is not always clear. In order to structure the discussion, we propose a classification of service granularity types that reflects three different interpretations. Firstly, functionality granularityrefers to how much functionality is offered by a service. Secondly, data granularityreflects the amount of data that is exchanged with a service. Finally, the business value granularityof a service indicates to which extent the service provides added business value. For each of these types, we discuss the impact of granularity on a set of architectural concerns, such as performance, reusability and flexibility. We illustrate each granularity type with small examples and we present some preliminary ideas of how controlling granularity may assist in alleviating some architectural issues as we encounter them in a large-sized bank-insurance company that is currently migrating to SOA.

A layered software specification architecture

Separation of concerns is a determining factor of the quality of object-oriented software development. Done well, it can provide substantial benefits such as additive rather than invasive change and improved adaptability, customizability, and reuse. In this paper we propose a software architecture that integrates concepts from business process modeling with concepts of object-oriented systems development. The presented architecture is a layered one: the concepts are arranged in successive layers in such a way that each layer only uses concepts of its own layer or of layers below. The guiding principle in the design of this layered architecture is the separation of concerns. On the one hand workflow aspects are separated from functional support for tasks and on the other hand domain modeling concepts are separated from information system support. The concept of events (workflow events, information system events and business events) is used as bridging concept between the different layers.

RE-CONFIGURING WORKFLOW MANAGEMENT SYSTEMS TO FACILITATE A "SMOOTH FLOW OF WORK"

The image of workflow systems as being context-insensitive technology, hindering rather than supporting people in performing their work may still exist at present. This impression is also raised in the well-known and often cited case study within Establishment Printers. Using this case as a starting point, this paper presents an analysis of more recent workflow implementations to support the view that modern workflow systems are widely applied in the services industry and are considered useful by performers to support their way of working. In cases where the introduction of workflow technology initially disrupted the flow of work, a wide range of configuration options was available to mend such situations. A detailed analysis of a workflow implementation in a Belgian financial organization clearly shows that re-configuration decisions, like a finer step granularity, can transform a pre-structured production-type workflow system into a flexible application allowing and supporting a smooth flow of work.

Workarounds and distributed viscosity in a workflow system: a case study

This research aims at studying enduser acceptance of workflow system. Enduser acceptance is crucial when considering the implementation success of workflow systems (WFS). The case study reported here is the first step in the development of a general diagnostic tool for evaluating the implementation of workflow systems.Many case studies have been presented in the field of Workflow Management [1;2;3]. Some focus on the design of WFS tools, others are ethnographic in nature and describe the factors that lead to success or failure of the WFS. However, most case studies provide case-specific insights and no general systematic framework has been presented yet to evaluate workflow implementation.

An architecture for bridging OO and business process modelling

Workflow systems and object-oriented technology have undoubtedly been some of the most important domains of interest of information technology over the past decade. Both domains however, have largely evolved independently, and not much research can be found in which workflow modelling principles and concepts have been applied to OO systems development or vice versa. We show how the two domains can be integrated. By integrating both domains, business process modelling can benefit from the advantages of the object-oriented approach. On the other hand, a more process oriented approach to OO development would enhance the organisational fit of object-oriented information systems development. The architecture that results from this integration is a tier-based one with a separate tier for workflow aspects.

Investigating the success of operational business process management systems

Business process management systems (BPMS) belong to a class of enterprise information systems that are characterized by the dependence on explicitly modeled process logic. Through the process logic, it is relatively easy to manage explicitly the routing and allocation of work items along a business process through the system. Inspired by the DeLone and McLean framework, we theorize that these process-aware system features are important attributes of system quality, which in turn will elevate key user evaluations such as perceived usefulness, and usage satisfaction. We examine this theoretical model using data collected from four different, mostly mature BPM system projects. Our findings validate the importance of input quality as well as allocation and routing attributes as antecedents of system quality, which, in turn, determines both usefulness and satisfaction with the system. We further demonstrate how service quality and workflow dependency are significant precursors to perceived usefulness. Our results suggest the appropriateness of a multi-dimensional conception of system quality for future research, and provide important design-oriented advice for the design and configuration of BPMSs.

Bridging User Story Sets with the Use Case Model

User Stories (US) are mostly used as basis for representing requirements in agile development. Written in a direct manner, US fail in producing a visual representation of the main system-to-be functions. A Use-Case Diagram (UCD), on the other hand, intends to provide such a view. Approaches that map US sets to a UCD have been proposed; they however consider every US as a Use Case (UC). Nevertheless, a valid UC should not be an atomic task or a sub-process but enclose an entire scenario of the system use instead. A unified model of US templates to tag US sets was previously build. Within functional elements, it notably distinguishes granularity levels. In this paper, we propose to transform specific elements of a US set into a UCD using the granularity information obtained through tagging. In practice, such a transformation involves continuous round-tripping between the US and UC views; a CASE-tool supports this.

Requirements-Driven Iterative Project Planning

Organizational modeling with the i* framework has widely been used for model-driven software development adopting a transformational approach, notably within the Tropos process. Its high-level representation elements allow to partition the software problem into adequate and manageable elements (actors, goals, tasks, resources and dependencies) leading to an agent-oriented design, and eventually an implementation with agent technologies (JACK, Jadex, Chimera Agent, ...). This paper proposes to use the i* framework for iterative software planning; each of the goals from the i* strategic dependency model are evaluated on the basis of the (high-level) threats they face and the expected quality factors. This allows to determine a priority among the model goals and “feed” an iterative template to plan the whole project realization. This framework is thus meant to be applied during the first iteration of the project for model-driven software project management. The development of a production management system in the steel industry is used as an example.

Building a rationale diagram for evaluating user story sets

Requirements representation in agile methods is often done on the basis of User Stories (US) which are short sentences relating a WHO, WHAT and (possibly) WHY dimension. They are by nature very operational and simple to understand thus very efficient. Previous research allowed to build a unified model for US templates associating semantics to a set of keywords based on templates collected over the web and scientific literature. Since the semantic associated to these keywords is mostly issued of the i* framework we overview in this paper how to build a custom rationale diagram on the basis of a US set tagged using that unified template. The rationale diagram is strictly speaking not an i* strategic rationale diagram but uses parts of its constructs and visual notation to build various trees of relating US elements in a single project. Indeed, the benefits of editing such a rationale diagram is to identify depending US, identifying EPIC ones and group them around common Themes. The paper shows the feasibility of building the rationale diagram, then points to the use of these consistent sets of US for iteration content planning. To ensure the US set and the rationale diagram constitute a consistent and not concurrent whole, an integrated Computer-Aided Software Engineering (CASE) tool supports the approach.

Assessing the influence of feedback-inclusive rapid prototyping on understanding the semantics of parallel UML statecharts by novice modellers

Abstract Context UML diagrams are the de facto standard for analysing, communicating and designing software systems, as well as automated code generation. However there is a certain degree of difficulty in understanding a system represented by means of UML diagrams. Object Our previous research demonstrates a significant improvement in understanding the structural aspects of a system represented as a UML class diagram when using a feedback-inclusive prototype of a model. This paper extends our previous work with an empirical validation study for the effectiveness of the feedback-inclusive rapid prototyping (FIRP) method, on the comprehension of system dynamics represented as multiple interacting UML statecharts . Because models often combine structural and behavioural views that are highly intertwined, we additionally evaluate the effectiveness of the proposed method with respect to comprehension of the between-view consistency. Method The FIRP environment was built following the principles of Design Science Research in Information Systems. This study targets the empirical validation of the effectiveness of the proposed technique using an experimental study method. Two experiments were conducted with the participation of 65 final-year master students in the context of different modelling courses from different study programs at KU Leuven using two two-group factorial experimental designs. The effectiveness of the FIRP method was measured by comparing students’ performance between the cycles with and without the use of the method, using the understandability (comprehension test results) as the dependent variable and the use of FIRP as the independent variable. Effects from unknown variables were neutralized by means of randomized group compositions. The effectiveness of FIRP was additionally assessed with respect to personal characteristics (age, gender, previous knowledge, self-efficacy) and user acceptance (perceived ease of use, perceived utility, preference, satisfaction). Results The findings reveal a significant positive impact of the use of the prototyping technique on students’ comprehension of system dynamics represented as multiple interacting statecharts. Conclusions The findings provide empirical support for the advantage of the use of FIRP over manual inspection of interacting statecharts. The findings also suggest that the method is suitable for training systems analysis and modelling skills when UML statecharts are involved.