Philip Langer

An Example Is Worth a Thousand Words: Composite Operation Modeling By-Example

Predefined composite operations are handy for efficient modeling, e.g., for the automatic execution of refactorings, and for the introduction of patterns in existing models. Some modeling environments provide an initial set of basic refactoring operations, but hardly offer any extension points for the user. Even if extension points exist, the introduction of new composite operations requires programming skills and deep knowledge of the respective metamodel. In this paper, we introduce a method for specifying composite operations within the users modeling language and environment of choice. The user models the composite operation by-example, which enables the semi-automatic derivation of a generic composite operation specification. This specification may be used in various modeling scenarios, like model refactoring and model versioning. We implemented the approach in the Operation Recorder and performed an evaluation by defining multiple complex refactorings for UML diagrams.

Model transformation by-example: a survey of the first wave

Model-Driven Engineering (MDE) places models as first-class artifacts throughout the software lifecycle. In this context, model transformations are crucial for the success of MDE, being comparable in role and importance to compilers for high-level programming languages. Thus, several model transformation approaches have been developed in the last decade, whereby originally most of them are based on the abstract syntax of modeling languages. However, this implementation specific focus makes it difficult for modelers to develop model transformations, because they are familiar with the concrete syntax but not with its computer internal representation. To tackle this problem, model transformation by-example approaches have been proposed which follow the same fundamental idea as query by-example and programming by-example approaches. Instead of using the computer internal representation of models, examples represented in concrete syntax are used to define transformations. Because different transformation scenarios occur in MDE, different by-example approaches have been developed. This chapter gives an overview on the emerging concepts, techniques, and approaches in this young by-example area.

xMOF: Executable DSMLs Based on fUML

The basic ingredients of a domain-specific modeling language (DSML) are its syntax and semantics. For defining the abstract syntax in terms of metamodels, MOF constitutes a standardized language. For specifying the behavioral semantics, however, no standardized language exists, which hampers the emergence of model execution facilities, such as debugging and simulation support. The contribution of this paper is an integrated approach for specifying the abstract syntax and behavioral semantics of DSMLs based exclusively on standardized modeling languages. In particular, we integrate fUML, a standardized executable subset of UML, with MOF leading to a new metamodeling language xMOF. Moreover, we propose a methodology for developing executable DSMLs fostering the separation of abstract syntax and behavioral semantics. To evaluate our approach, we provide an EMF-based implementation and report on lessons learned from performing three case studies in which we implemented executable DSMLs using xMOF.

EMF Profiles: A Lightweight Extension Approach for EMF Models.

Domain-Specific Modeling Languages (DSMLs) are getting more and more attention as a key element of Model Driven Engineering. As any other software artifact, DSMLs should continuously evolve to adapt to the changing needs of the domain they represent. Unfortunately, right now evolution of DSMLs is a costly process that requires changing the DSML metamodel and re-creating the complete modeling environment. In this paper we advocate for the use of EMF Profiles, an adaptation of the UML Profile concept to DSMLs. Profiles have been a key enabler for the success of UML by providing a lightweight language-inherent extension mechanism which is expressive enough to cover an important subset of extension scenarios. We believe a similar concept for DSMLs would provide a valuable extension mechanism which has been so far neglected by current metamodeling tools. Apart from direct metamodel profiles, we also propose reusable profile definition mechanisms whereby profiles are defined independently of any DSML and, later on, coupled with all DSMLs that can benefit from these profiles. Our approach has been implemented in a prototype integrated in the EMF environment.

Migrating Legacy Software to the Cloud with ARTIST

As cloud computing allows improving the quality of software and aims at reducing costs of operating software, more and more software is delivered as a service. However, moving from a software as a product strategy to delivering software as a service hosted in cloud environments is very ambitious. This is due to the fact that managing software modernization is still a major challenge, especially when paradigm shifts, such as moving to cloud environments, are targeted that imply fundamental changes to how software is modernized, delivered, and sold. Thus, in addition to technical aspects, business aspects need also to be considered. ARTIST proposes a comprehensive software modernization approach covering business and technical aspects. In particular, ARTIST employs Model-Driven Engineering (MDE) techniques to automate the reverse engineering of legacy software and forward engineering of cloud-based software in a way that modernized software truly benefits from targeted cloud environments. Therewith, ARTIST aims at reducing the risks, time, and costs of software modernization and lowers the barriers to exploit cloud computing capabilities and new business models.

A fundamental approach to model versioning based on graph modifications: from theory to implementation

In model-driven engineering, models are primary artifacts that can evolve heavily during their life cycle. Therefore, versioning of models is a key technique to be offered by integrated development environments for model-driven engineering. In contrast to text-based versioning systems, we present an approach that takes model structures and their changes over time into account. Considering model structures as graphs, we define a fundamental approach where model revisions are considered as graph modifications consisting of delete and insert actions. Two different kinds of conflict detection are presented: (1) the check for operation-based conflicts between different graph modifications, and (2) the check for state-based conflicts on merged graph modifications. For the merging of graph modifications, a two-phase approach is proposed: First, operational conflicts are temporarily resolved by always giving insertion priority over deletion to keep as much information as possible. Thereafter, this tentative merge result is the basis for manual conflict resolution as well as for the application of repair actions that resolve state-based conflicts. If preferred by the user, giving deletion priority over insertion might be one solution. The fundamental concepts are illustrated by versioning scenarios for simplified statecharts. Furthermore, we show an implementation of this fundamental approach to model versioning based on the Eclipse Modeling Framework as technical space.

An introduction to model versioning

With the emergence of model-driven engineering (MDE), software models are considered as central artifacts in the software engineering process, going beyond their traditional use as sketches. In MDE, models rather act as the single source of information for automatically generating executable software. This shift poses several new research challenges. One of these challenges constitutes model versioning, which targets at enabling efficient team-based development of models. This compelling challenge induced a very active research community, who yielded remarkable methods and techniques ranging from model differencing to merging of models. In this tutorial, we give an introduction to the foundations of model versioning, the underlying technologies for processing models and their evolution, as well as the state of the art in model versioning. Thereby, we aim at equipping students and researchers alike that are new to this domain with enough information for commencing to contribute to this challenging research area.

A runtime model for fUML

With the introduction of fUML, an OMG standard defining the operational semantics of a subset of UML and the conforming virtual machine, UML models can be used not only for informal design sketching but also for completely building executable systems. Although this has been an important step for UML, the full potential of having executable UML models, such as enabling runtime analysis and adaptation, cannot be realized using the standardized virtual machine due to the lack of the adequate means for accessing important runtime information and controlling the execution of UML models. In this paper, we aim at establishing the necessary basis to overcome this limitation. Therefore, we introduce extensions of the standardized fUML virtual machine in terms of a dedicated trace model, an event model, and a command API. We provide an open-source implementation of the proposed extensions, as well as a model debugger for UML models based on this implementation to demonstrate the feasibility of the presented concepts.

A posteriori operation detection in evolving software models

Highlights ► Detection of applications of composite operations in evolving software models. ► Automatic generation of detection rules from executable operation specifications. ► Real-world study showing that 70% of all applied composite operations can be detected. ► Performance analysis showing that detection algorithm scales well for large models.

Model-to-model transformations by demonstration

During the last decade several approaches have been proposed for easing the burden of writing model transformation rules manually. Among them are Model Transformation By-Demonstration (MTBD) approaches which record actions performed on example models to derive general operations. A current restriction of MTBD is that until now they are only available for in-place transformations, but not for model-to-model (M2M) transformations. In this paper, we extend our MTBD approach, which is designed for in-place transformations, to also support M2M transformations. In particular, we propose to demonstrate each transformation rule by modeling a source model fragment and a corresponding target model fragment. From these example pairs, the applied edit operations are computed which are input for a semi-automatic process for deriving the general transformation rules. For showing the applicability of the approach, we developed an Eclipse-based prototype supporting the generation of ATL code out of EMF-based example models.