A requirements engineering method for COTS-based systems development

An increasing number of organisations are procuring off-the-shelf software products from commercial suppliers. However, there has been a lack of methods and software tools for such requirements acquisition, product selection and product procurement. This thesis proposes a new method called PORE (Procurement-Oriented Requirements Engineering) which integrates existing requirements engineering techniques with those from knowledge engineering, feature analysis, multi-criteria decision-making and argumentation approaches to address the lack of guidance for acquiring requirements to enable evaluation and selection of commercial-off-the-shelf (COTS) software. PORE is designed in part from conclusions drawn from real-world case studies of requirements acquisition for complex software product selection. Such studies are reported in this thesis. The PORE method is part goal-driven and part context-driven, in that it exploits models of the candidate COTS software and customer requirements as well as process goals to guide a requirements engineering team. The method's approach and mechanisms is demonstrated using a well-known commercial electronic-mail system. A number of studies are presented to provide validation for the method. These include three studies in three different organisations to select COTS software products and one study of requirements engineering experts to elicit their knowledge. The results from these studies demonstrated that the method is usable and effective. The thesis concludes with a discussion of future work to improve the PORE method and future research directions on requirements engineering for COTS-based systems development

Conceptual fit: A criterion for COTS selection

COTS systems selection consists in evaluating the user requirements with respect to characteristics of candidate systems, using a set of criteria. One criterion that has received little attention is what we call conceptual fit. The criterion assesses the fit between the conceptual structure of the user requirements and that of a system. We evaluate the fit in terms of the existing misfits. We formally define the notion of conceptual misfit and we present a method that determines the conceptual misfits between the user requirements and a set of candidate systems. The method consists in defining a superschema, the mapping of the conceptual schemas of the candidate systems and of the user requirements to that superschema, and the automatic computation of the existing conceptual misfits. The method has been formalized in UML/OCL. We have conducted an exploratory experiment with the aim of evaluating the feasibility, difficulty and usefulness of the method, with positive results. We believe that the conceptual fit criterion could be taken into account by almost all existing COTS selection methods.Preprin

Uncertainty explicit assessment of off-the-shelf software: Selection of an optimal diverse pair

Assessment of software COTS components is an essential part of component-based software development. Sub-optimal selection of components may lead to solutions with low quality. The assessment is based on incomplete knowledge about the COTS components themselves and other aspects, which may affect the choice such as the vendor's credentials, etc. We argue in favor of assessment methods in which uncertainty is explicitly represented (`uncertainty explicit' methods) using probability distributions. We have adapted a model (developed elsewhere by Littlewood, B. et al. (2000)) for assessment of a pair of COTS components to take account of the fault (bug) logs that might be available for the COTS components being assessed. We also provide empirical data from a study we have conducted with off-the-shelf database servers, which illustrate the use of the method

An approach to reconcile the agile and CMMI contexts in product line development

Software product line approaches produce reusable platforms and architectures for products set developed by specific companies. These approaches are strategic in nature requiring coordination, discipline, commonality and communication. The Capability Maturity Model (CMM) contains important guidelines for process improvement, and specifies "what" we must have into account to achieve the disciplined processes (among others things). On the other hand, the agile context is playing an increasingly important role in current software engineering practices, specifying "how" the software practices must be addressed to obtain agile processes. In this paper, we carry out a preliminary analysis for reconciling agility and maturity models in software product line domain, taking advantage of both.Postprint (published version

Using quality models in software package selection

The growing importance of commercial off-the-shelf software packages requires adapting some software engineering practices, such as requirements elicitation and testing, to this emergent framework. Also, some specific new activities arise, among which selection of software packages plays a prominent role. All the methodologies that have been proposed recently for choosing software packages compare user requirements with the packages' capabilities. There are different types of requirements, such as managerial, political, and, of course, quality requirements. Quality requirements are often difficult to check. This is partly due to their nature, but there is another reason that can be mitigated, namely the lack of structured and widespread descriptions of package domains (that is, categories of software packages such as ERP systems, graphical or data structure libraries, and so on). This absence hampers the accurate description of software packages and the precise statement of quality requirements, and consequently overall package selection and confidence in the result of the process. Our methodology for building structured quality models helps solve this drawback.Peer ReviewedPostprint (published version

Uncertainty explicit assessment of off-the-shelf software: A Bayesian approach

Assessment of software COTS components is an essential part of component-based software development. Poorly chosen components may lead to solutions of low quality and that are difficult to maintain. The assessment may be based on incomplete knowledge about the COTS component itself and other aspects (e.g. vendor’s credentials, etc.), which may affect the decision of selecting COTS component(s). We argue in favor of assessment methods in which uncertainty is explicitly represented (‘uncertainty explicit’ methods) using probability distributions. We provide details of a Bayesian model, which can be used to capture the uncertainties in the simultaneous assessment of two attributes, thus, also capturing the dependencies that might exist between them. We also provide empirical data from the use of this method for the assessment of off-the-shelf database servers which illustrate the advantages of ‘uncertainty explicit’ methods over conventional methods of COTS component assessment which assume that at the end of the assessment the values of the attributes become known with certainty

A framework for selecting workflow tools in the context of composite information systems

When an organization faces the need of integrating some workflow-related activities in its information system, it becomes necessary to have at hand some well-defined informational model to be used as a framework for determining the selection criteria onto which the requirements of the organization can be mapped. Some proposals exist that provide such a framework, remarkably the WfMC reference model, but they are designed to be appl icable when workflow tools are selected independently from other software, and departing from a set of well-known requirements. Often this is not the case: workflow facilities are needed as a part of the procurement of a larger, composite information syste m and therefore the general goals of the system have to be analyzed, assigned to its individual components and further detailed. We propose in this paper the MULTSEC method in charge of analyzing the initial goals of the system, determining the types of components that form the system architecture, building quality models for each type and then mapping the goals into detailed requirements which can be measured using quality criteria. We develop in some detail the quality model (compliant with the ISO/IEC 9126-1 quality standard) for the workflow type of tools; we show how the quality model can be used to refine and clarify the requirements in order to guarantee a highly reliable selection result; and we use it to evaluate two particular workflow solutions a- ailable in the market (kept anonymous in the paper). We develop our proposal using a particular selection experience we have recently been involved in, namely the procurement of a document management subsystem to be integrated in an academic data management information system for our university.Peer ReviewedPostprint (author's final draft

A Systematic Mapping Study on Off-The-Shelf-based Software Acquisition

Acquiring software from external suppliers and developing less software in-house can help software-developing organizations improve operational efficiency by reducing costs, time and reusing current technologies. Software projects increasingly use Off-The-Shelf (OTS) products. From the acquirer perspective, there is a need to understand in more detail OTS-based software acquisition processes, because they are different to and less well-understood than those for the acquisition of custom software. In this paper we have undertaken a systematic mapping study on OTS-based software acquisition. The study compares and contrasts OTS-based software acquisition and non-OTS-based software acquisition, and identifies factors influencing decision making in OTS-based software acquisition. We find that the main difference is that there is a relationship between determining the software requirements and OTS selection in OTS-based software acquisition. For commercial OTS software, the major factors are functionality and quality of the software, but for open-source OTS software, cost was the most important factor