An approach to engineering the requirements of data warehouses

We focus exclusively on the issue of Requirements engineering for Data Warehouses (DW). Our position is that the information content of a DW is found in the larger context of the goals of an organization. We refer to this context as the organizational perspective. Goals identify the set of decisions that are relevant which in turn help in determining the information needed to support these. The organizational perspective is converted into the technical perspective, which deals with the set of decisions to be supported and the information required. The latter defines Data warehouse contents. To elicit the technical perspective, we use the notion of an informational scenario. It is a typical interaction between a DW system and the decision maker and consists of a sequence of pairs of the form, <information request, response>. We formulate an information request as a statement in an adapted form of SQL called Specification SQL. The proposals here are implemented in the form of an Informational Scenario Engine that processes informational scenarios and determines Data Warehouse Information Contents.     

A requirement-driven approach to the design and evolution of data warehouses

Designing data warehouse (DW) systems in highly dynamic enterprise environments is not an easy task. At each moment, the multidimensional (MD) schema needs to satisfy the set of information requirements posed by the business users. At the same time, the diversity and heterogeneity of the data sources need to be considered in order to properly retrieve needed data. Frequent arrival of new business needs requires that the system is adaptable to changes. To cope with such an inevitable complexity (both at the beginning of the design process and when potential evolution events occur), in this paper we present a semi-automatic method called ORE, for creating DW designs in an iterative fashion based on a given set of information requirements. Requirements are first considered separately. For each requirement, ORE expects the set of possible MD interpretations of the source data needed for that requirement (in a form similar to an MD schema). Incrementally, ORE builds the unified MD schema that satisfies the entire set of requirements and meet some predefined quality objectives. We have implemented ORE and performed a number of experiments to study our approach. We have also conducted a limited-scale case study to investigate its usefulness to designers.     

Two approaches to the integration of heterogeneous data warehouses

In this paper we address the problem of integrating independent and possibly heterogeneous data warehouses, a problem that has received little attention so far, but that arises very often in practice. We start by tackling the basic issue of matching heterogeneous dimensions and provide a number of general properties that a dimension matching should fulfill. We then propose two different approaches to the problem of integration that try to enforce matchings satisfying these properties. The first approach refers to a scenario of loosely coupled integration, in which we just need to identify the common information between data sources and perform join operations over the original sources. The goal of the second approach is the derivation of a materialized view built by merging the sources, and refers to a scenario of tightly coupled integration in which queries are performed against the view. We also illustrate architecture and functionality of a practical system that we have developed to demonstrate the effectiveness of our integration strategies. A preliminary version this paper appeared, under the title “Integrating Heterogeneous Multidimensional Databases” [9], in 17th Int. Conference on Scientific and Statistical Database Management, 2005.     

企业级数据仓库设计方法及其实施的关键因素研究

数据仓库是支持企业全局决策的有效技术．首先讨论了数据仓库的基本结构和组成，并给出了数据仓库系统的形式化描述；然后给出了基于软件工程思想的具有7个阶段的数据仓库设计方法，并详细讨论了各个阶段的主要工作和技术；最后，给出了成功建设数据仓库的关键因素的分类．     

Architecture and quality in data warehouses: An extended repository approach

Most database researchers have studied data warehouses (DW) in their role as buffers of materialized views, mediating between update-intensive OLTP systems and query-intensive decision support. This neglects the organizational role of data warehousing as a means of centralized information flow control. As a consequence, a large number of quality aspects relevant for data warehousing cannot be expressed with the current DW meta models. This paper makes two contributions towards solving these problems. Firstly, we enrich the meta data about DW architectures by explicit enterprise models. Secondly, many very different mathematical techniques for measuring or optimizing certain aspects of DW quality are being developed. We adapt the Goal-Question-Metric approach from software quality management to a meta data management environment in order to link these special techniques to a generic conceptual framework of DW quality. The approach has been implemented in full on top of the ConceptBase repository system and has undergone some validation by applying it to the support of specific quality-oriented methods, tools, and application projects in data warehousing.     

Supporting the design of office layout meeting ergonomics requirements

This paper proposes a method and an information technology tool aiming to support the ergonomics layout design of individual workstations in a given space (building). The proposed method shares common ideas with previous generic methods for office layout. However, it goes a step forward and focuses on the cognitive tasks which have to be carried out by the designer or the design team trying to alleviate them. This is achieved in two ways: (i) by decomposing the layout design problem to six main stages, during which only a limited number of variables and requirements are considered and (ii) by converting the ergonomics requirements to functional design guidelines. The information technology tool (ErgoOffice 0.1) automates certain phases of the layout design process, and supports the design team either by its editing and graphical facilities or by providing adequate memory support.     

Supporting the acquisition and modeling of requirements in software design

This paper describes a system for supporting the construction of software requirement models, which are initial computable models representing users' requirements in software design. The system principally consists of two components, a system for aiding the formation of requirement concepts by visualizing a user's thought space, and a knowledge-based system which automatically assembles the ascertained requirement concepts into a requirement model. The system extracts reusable components of a requirement model, corresponding to the users' abstract requirement concept, from a store of similar past cases. The components are then automatically arranged using heuristic reasoning. By using the system, users can make their requirement concepts more mature, and simultaneously get computable requirement models as by-products.     

Spatial data warehouses and spatial OLAP come towards the cloud: design and performance

Cloud computing systems handle large volumes of data by using almost unlimited computational resources, while spatial data warehouses (SDWs) are multidimensional databases that store huge volumes of both spatial data and conventional data. Cloud computing environments have been considered adequate to host voluminous databases, process analytical workloads and deliver database as a service, while spatial online analytical processing (spatial OLAP) queries issued over SDWs are intrinsically analytical. However, hosting a SDW in the cloud and processing spatial OLAP queries over such database impose novel obstacles. In this article, we introduce novel concepts as cloud SDW and spatial OLAP as a service, and afterwards detail the design of novel schemas for cloud SDW and spatial OLAP query processing over cloud SDW. Furthermore, we evaluate the performance to process spatial OLAP queries in cloud SDWs using our own query processor aided by a cloud spatial index. Moreover, we describe the cloud spatial bitmap index to improve the performance to process spatial OLAP queries in cloud SDWs, and assess it through an experimental evaluation. Results derived from our experiments revealed that such index was capable to reduce the query response time from 58.20 up to 98.89 %.     

Four integration patterns: a socio-technical approach to integration in IS development projects

This paper aims to contribute to a theory of integration within the field of information systems (IS) project management. Integration is a key IS project management issue when new systems are developed and implemented into an increasingly integrated information infrastructure in corporate and governmental organizations. Expanding the perspective of traditional project management research, we draw extensively on central insights from IS research. Building on socio-technical IS research and software engineering research, we suggest four generic patterns of integration: big bang, stakeholder integration, technical integration and socio-technical integration. We analyse and describe the advantages and disadvantages of each pattern. The four patterns are ideal types. To explore the forces and challenges in these patterns, three longitudinal case studies were conducted. In particular we investigate the management challenges for each pattern. We find that the patterns are context-sensitive and describe the different contexts where the patterns are applicable. For IS project management, the four integration patterns are a contribution to the management of integration risks – extending the vocabulary for assessing and mitigating these risks in IS development. For practitioners the four integration patterns represent an analytical framework to be used in planning modern IS development projects.     

Multimedia data warehouses: a multiversion model and a medical application

Histogram feature representation is important in many classification applications for characterization of the statistical distribution of different pattern attributes, such as the color and edge orientation distribution in images. While the construction of these feature representations is simple, this very simplicity may compromise the classification accuracy in those cases where the original histogram does not provide adequate discriminative information for making a reliable classification. In view of this, we propose an optimization approach based on evolutionary computation (Back, Evolutionary algorithms in theory and practice, Oxford University Press, New York, 1996; Fogel, Evolutionary computation: toward a new philosophy of machine intelligence, 2nd edn. IEEE, Piscataway, NJ 1998) to identify a suitable transformation on the histogram feature representation, such that the resulting classification performance based on these features is maximally improved while the original simplicity of the representation is retained. To facilitate this optimization process, we propose a hierarchical classifier structure to demarcate the set of categories in such a way that the pair of category subsets with the highest level of dissimilarities is identified at each stage for partition. In this way, the evolutionary search process for the required transformation can be considerably simplified due to the reduced level of complexities in classification for two widely separated category subsets. The proposed approach is applied to two problems in multimedia data classification, namely the categorization of 3D computer graphics models and image classification in the JPEG compressed domain. Experimental results indicate that the evolutionary optimization approach, facilitated by the hierarchical classification process, is capable of significantly improving the classification performance for both applications based on the transformed histogram representations.

Identifying requirements for communication support: A maturity grid-inspired approach

Communication is a critical success factor in design. It can be seen as the social and cognitive process by which information is selected, messages are exchanged between interacting partners, and meaning is created. How communication processes can best be captured, analysed and assessed, as a preliminary step toward suggestions for improvement of communication practices, remains a challenge for researchers and practitioners. To this end, a maturity grid-inspired approach to audit communication practices has been developed. This paper employs a maturity grid approach and reflects critically on the construction and application of the approach in a structured group workshop in software design. Such an approach yields dual benefits: (a) as a research method to gather insight into communication and (b) as a guide to plan improvements in practice. Conclusions are drawn for the process of auditing communication in design.     

From requirements to implementations: a model-driven approach for web development

Model-Driven Development (MDD) is an appropriate paradigm for web development since interoperability and flexibility are required to cope with implementation technologies and functionalities that are in permanent evolution. In this paper, we describe and illustrate the MDD process of the ADM (Ariadne Development Method) hypermedia/web engineering method. The two cornerstones of the ADM are the Labyrinth++ meta-meta-model, which formalizes the core constructs used within all the design meta-models, and the meta-meta-model specification as an ontology that provides semantics and reasoning not only for model transformations but also for consistency checking and model validation. These features have been essential in the development of a CASE tool, called AriadneTool that supports the different abstract levels of modeling, model transformations as well as the generation of light prototypes in different web implementation technologies.     

An integrative approach to requirements analysis: How task models support requirements reuse in a user-centric design framework

Many software systems fail to address their intended purpose because of a lack of user involvement and requirements deficiencies. This paper discusses the elaboration of a requirements-analysis process that integrates a critical-parameter-based approach to task modeling within a user-centric design framework. On one hand, adapting task models to capture requirements bridges the gap between scenarios and critical parameters which benefits design from the standpoint of user involvement and accurate requirements. On the other hand, using task models as a reusable component leverages requirements reuse which benefits design by increasing quality while simultaneously reducing development costs and time-to-market. First, we present the establishment of both a user-centric and reuse-centric requirements process along with its implementation within an integrated design tool suite. Secondly, we report the design, procedures, and findings of two user studies aimed at assessing the feasibility for novice designers to conduct the process as well as evaluating the resulting benefits upon requirements-analysis deliverables, requirements quality, and requirements reuse.     

Economic sizing of warehouses: A linear programming approach

Determining the best size for a private warehouse is a planning problem which can affect the overall operations of the firm for many years into the future. A linear programming formulation is presented which determines the optimal size warehouse to construct when demand is highly seasonal and public warehouse space is available on a monthly basis. The model is then extended for the dynamic sizing problem in which the warehouse size is allowed to change over time.     

Supporting user participation design using a fuzzy analytic hierarchy process approach

There are three fundamental problems that may occur in the process of user participation design: first, the participants/users may not be able to express their requirements clearly; second, they have little knowledge about design; and third, they are generally unfamiliar with the software that designers use. Based on this understanding, a method that considers design rationale is proposed in this work to support the process of user participation design. In addressing the user participation process, a fuzzy analytic hierarchy process (AHP) approach is applied to grasp people's ideas, in the initial design phase. A case study on creating house layout design is employed to illustrate the proposed approach. In this regard, to help participants/users create layout designs, it is proposed that a 3D generative system is used, which integrates navigational concepts, direct manipulation, and the design rationale theory. In a nutshell, this research proposes a system to implement a design rational model and improve design communication in the user participation process. To demonstrate the effectiveness of the proposed prototype system, a user test is performed and we put forward some findings and research questions for further research and industry practices.     

A trace metamodel proposal based on the model driven architecture framework for the traceability of user requirements in data warehouses

The complexity of the data warehouse (DW) development process requires to follow a methodological approach in order to be successful. A widely accepted approach for this development is the hybrid one, in which requirements and data sources must be accommodated to a new DW model. The main problem is that we lose the relationships between requirements, elements in the multidimensional (MD) conceptual models and data sources in the process, since no traceability is explicitly specified. Therefore, this hurts requirements validation capability and increases the complexity of Extraction, Transformation and Loading processes. In this paper, we propose a novel trace metamodel for DWs and focus on the relationships between requirements and MD conceptual models. We propose a set of Query/View/Transformation rules to include traceability in DWs in an automatic way, allowing us to obtain a MD conceptual model of the DW, as well as a trace model. Therefore, we are able to trace every requirement to the MD elements, further increasing user satisfaction. Finally, we show the implementation in our Lucentia BI tool.     

A method to elicit architecturally sensitive usability requirements: its integration into a software development process

In the Human-Computer Interaction (HCI) community, software usability has primarily been concerned with the presentation of information, more precisely with the user interface. However, some usability problems can prove costly to fix if the changes require modifications that reach beyond the presentation layer, namely those that cannot be easily accommodated by the software architecture. Taking into account some usability requirements earlier in the software development cycle, specifically prior to the architectural design phase, can reduce the cost of these modifications. There is a scarcity of methods and guidelines with the scope to direct users in eliciting the usability requirements that can impact the software architecture. This paper proposes a usability-driven adaptation of the quality attribute workshop (QAW) to assist software development organizations in discovering and documenting usability requirements. It shows how this method can be integrated into a software development process, by discussing how the existing software framework workflows can be adjusted to take this new activity into consideration. A preliminary exercise was conducted to help discern the utility and the limits of the proposed method. Participants with different levels of knowledge of usability and comprehension of the system being developed found the method constructive, as it guided them in identifying the architecturally relevant usability requirements. It also helped determine the usability aspects that would not necessarily have been defined if this technique had not been employed.