Designing precise and flexible graphical modelling languages for software development

Model-driven approaches to software development involve building computerized models of software and the environment in which it is intended to operate. This thesis offers a selection of the author’s work over the last three decades that addresses the design of precise and flexible graphical modelling languages for use in model-driven software development. The primary contributions of this work are: • Syntropy: the first published object-oriented analysis and design (OOAD) method to fully integrate formal and graphical modelling techniques. • The creation of the Object Constraint Language (OCL) and its integration into the Unified Modeling Language (UML) specification. • The identification of requirements and mechanisms for increasing the flexibility of the UML specification. • The design and implementation of tools for implementing graphical Domain Specific Languages (DSLs). The starting point was the author’s experience with formal specification techniques contrasted with the lack of precision of published object-oriented analysis and design methods. This led to a desire to fully integrate these two topics – formal specification and object-orientation - into a coherent discipline. The Syntropy approach, created in 1994 by this author and John Daniels, was the first published complete attempt to do this. Much of the author’s subsequent published work concerns the Unified Modeling Language (UML). UML represented a welcome unification of earlier OOAD approaches, but suffered badly from inflexibility and lack of precision. A significant part of the work included in this thesis addresses the drawbacks of the UML and proposes improvements to the precision of its definition, including through the invention of Object Constraint Language (OCL) and its incorporation into the UML specification, and the consideration of UML as source material for the definition of Domain Specific Languages (DSLs). Several of the author’s published works in this thesis concern mechanisms for the creation of DSLs, both within a UML framework and separately

Supporting the grow-and-prune model for evolving software product lines

207 p.Software Product Lines (SPLs) aim at supporting the development of a whole family of software products through a systematic reuse of shared assets. To this end, SPL development is separated into two interrelated processes: (1) domain engineering (DE), where the scope and variability of the system is defined and reusable core-assets are developed; and (2) application engineering (AE), where products are derived by selecting core assets and resolving variability. Evolution in SPLs is considered to be more challenging than in traditional systems, as both core-assets and products need to co-evolve. The so-called grow-and-prune model has proven great flexibility to incrementally evolve an SPL by letting the products grow, and later prune the product functionalities deemed useful by refactoring and merging them back to the reusable SPL core-asset base. This Thesis aims at supporting the grow-and-prune model as for initiating and enacting the pruning. Initiating the pruning requires SPL engineers to conduct customization analysis, i.e. analyzing how products have changed the core-assets. Customization analysis aims at identifying interesting product customizations to be ported to the core-asset base. However, existing tools do not fulfill engineers needs to conduct this practice. To address this issue, this Thesis elaborates on the SPL engineers' needs when conducting customization analysis, and proposes a data-warehouse approach to help SPL engineers on the analysis. Once the interesting customizations have been identified, the pruning needs to be enacted. This means that product code needs to be ported to the core-asset realm, while products are upgraded with newer functionalities and bug-fixes available in newer core-asset releases. Herein, synchronizing both parties through sync paths is required. However, the state of-the-art tools are not tailored to SPL sync paths, and this hinders synchronizing core-assets and products. To address this issue, this Thesis proposes to leverage existing Version Control Systems (i.e. git/Github) to provide sync operations as first-class construct

Designing Round-Trip Systems by Change Propagation and Model Partitioning

Software development processes incorporate a variety of different artifacts (e.g., source code, models, and documentation). For multiple reasons the data that is contained in these artifacts does expose some degree of redundancy. Ensuring global consistency across artifacts during all stages in the development of software systems is required, because inconsistent artifacts can yield to failures. Ensuring consistency can be either achieved by reducing the amount of redundancy or by synchronizing the information that is shared across multiple artifacts. The discipline of software engineering that addresses these problems is called Round-Trip Engineering (RTE). In this thesis we present a conceptual framework for the design RTE systems. This framework delivers precise definitions for essential terms in the context of RTE and a process that can be used to address new RTE applications. The main idea of the framework is to partition models into parts that require synchronization - skeletons - and parts that do not - clothings. Once such a partitioning is obtained, the relations between the elements of the skeletons determine whether a deterministic RTE system can be built. If not, manual decisions may be required by developers. Based on this conceptual framework, two concrete approaches to RTE are presented. The first one - Backpropagation-based RTE - employs change translation, traceability and synchronization fitness functions to allow for synchronization of artifacts that are connected by non-injective transformations. The second approach - Role-based Tool Integration - provides means to avoid redundancy. To do so, a novel tool design method that relies on role modeling is presented. Tool integration is then performed by the creation of role bindings between role models. In addition to the two concrete approaches to RTE, which form the main contributions of the thesis, we investigate the creation of bridges between technical spaces. We consider these bridges as an essential prerequisite for performing logical synchronization between artifacts. Also, the feasibility of semantic web technologies is a subject of the thesis, because the specification of synchronization rules was identified as a blocking factor during our problem analysis. The thesis is complemented by an evaluation of all presented RTE approaches in different scenarios. Based on this evaluation, the strengths and weaknesses of the approaches are identified. Also, the practical feasibility of our approaches is confirmed w.r.t. the presented RTE applications