Cube Algebra

The lack of an appropriate conceptual model for data warehouses and OLAP systems has led to the tendency to deploy logical models (for example, star, snowflake, and constellation schemas) for them as conceptual models. ER model extensions, UML extensions, special graphical user interfaces, and dashboards have been proposed as conceptual approaches. However, they introduce their own problems, are somehow complex and difficult to understand, and are not always user-friendly. They also require a high learning curve, and most of them address only structural design, not considering associated operations. Therefore, they are not really an improvement and, in the end, only represent a reflection of the logical model. The essential drawback of offering this system-centric view as a user concept is that knowledge workers are confronted with the full and overwhelming complexity of these systems as well as complicated and user-unfriendly query languages such as SQL OLAP and MDX. In this article, the authors propose a user-centric conceptual model for data warehouses and OLAP systems, called the Cube Algebra. It takes the cube metaphor literally and provides the knowledge worker with high-level cube objects and related concepts. A novel query language leverages well known high-level operations such as roll-up, drill-down, slice, and drill-across. As a result, the logical and physical levels are hidden from the unskilled end user.

Applying UML Extensions in Modeling Software Product Line Architecture of a Distribution Services Platform

UML provides the means to use specific variation mechanisms to describe hierarchical systems. However, it does not support a description of variation, as it is required for service architecture. UML built-in extension mechanisms refine its specification. This chapter presents the extensions of the UML for representing variations in the software product line architecture of middleware services. The product line is defined as a middleware services framework that includes several products. The products realize different functionality by using various modern software technologies of spontaneous networks. Architecture design produces descriptions at two abstraction levels from multiple viewpoints. The modeling of service architectures benefits from a more familiar and widely used notation that improves stakeholders’ understanding of the architectural artifacts. A standard based notation also enables more extensive tool support for manipulating architecture models.

Modeling Variant User Interfaces for Web-Based Software Product Lines

Software product line (SPL) is a software engineering paradigm for software development. SPL is important in promoting software reuse, leading to higher productivity and quality. A software product within a product line often has specific functionalities that are not common to all other products within the product line. Those specific functionalities are termed “variant features” in a product line. SPL paradigm involves the modeling of variant features. However, little work in SPL investigates and addresses the modeling of variant features specific to UI. UML is the de facto modeling language for object-oriented software systems. It is known that UML needs better support in modeling UIs. Thus, much research developed UML extensions to improve UML support in modeling UIs. Yet little of this work is related to developing such extensions for modeling UIs for SPLs in which variant features specific to user interfaces (UI) modeling must be addressed. This research develops a UML extension, WUIML, to address these problems. WUIML defines elements for modeling variant features specific to UIs for Web-based SPLs. The model elements in WUIML extend from the metaclass and of the UML2.0 metamodel. WUIML integrates the modeling of variant features specific to UIs to UML. For example, in a Web-based patient registration SPL, member products targeting British users may use British date format in the user interface, while member products targeting United States users may use United States date format in the user interface. Thus, this is a variant feature for this product line. WUIML defines a model element, XOR, to represent such exclusive or conditions in a product line user interface model. WUIML would reduce SPL engineers’ efforts needed in UI development. To validate the WUIML research outcome, a case study was conducted. The results of this empirical study indicate that modeling UIs for Web-based SPLs using WUIML is more effective and efficient than using standard UML.