From types to type requirements: Genericity for model-driven engineering

The final publication is available at Springer via http://dx.doi.org/10.1007/s10270-011-0221-0Model-driven engineering (MDE) is a software engineering paradigm that proposes an active use of models during the development process. This paradigm is inherently type-centric, in the sense that models and their manipulation are defined over the types of specific meta-models. This fact hinders the reuse of existing MDE artefacts with other meta-models in new contexts, even if all these meta-models share common characteristics. To increase the reuse opportunities of MDE artefacts, we propose a paradigm shift from type-centric to requirement-centric specifications by bringing genericity into models, meta-models and model management operations. For this purpose, we introduce so-called concepts gathering structural and behavioural requirements for models and meta-models. In this way, model management operations are defined over concepts, enabling the application of the operations to any meta-model satisfying the requirements imposed by the concept. Model templates rely on concepts to define suitable interfaces, hence enabling the definition of reusable model components. Finally, similar to mixin layers, templates can be defined at the meta-model level as well, to define languages in a modular way, as well as layers of functionality to be plugged-in into other meta-models. These ideas have been implemented in MetaDepth, a multi-level meta-modelling tool that integrates action languages from the Epsilon family for model management and code generation.This work has been sponsored by the Spanish Ministry of Science and Innovation with projects METEORIC (TIN2008-02081) and Go Lite (TIN2011-24139), and by the R&D program of the Community of Madrid with project “e-Madrid” (S2009/TIC-1650)

gbeta - a Language with Virtual Attributes, Block Structure, and Propagating, Dynamic Inheritance

A language design development process is presented which leads to a language, gbeta, with a tight integration of virtual classes, general block structure, and a multiple inheritance mechanism based on coarse-grained structural type equivalence. From this emerges the concept of propagating specialization. The power lies in the fact that a simple expression can have far-reaching but well-organized consequences, e.g., in one step causing the combination of families of classes, then by propagation the members of those families, and finally by propagation the methods of the members. Moreover, classes are first class values which can be constructed at run-time, and it is possible to inherit from classes whether or not they are compile-time constants, and whether or not they were created dynamically. It is also possible to change the class and structure of an existing object at run-time, preserving object identity. Even though such dynamism is normally not seen in statically type-checked languages, these constructs have been integrated without compromising the static type safety of the language

Object-Centric Reflection: Unifying Reflection and Bringing It Back to Objects

Reflective applications are able to query and manipulate the structure and behavior of a running system. This is essential for highly dynamic software that needs to interact with objects whose structure and behavior are not known when the application is written. Software analysis tools, like debuggers, are a typical example. Oddly, although reflection essentially concerns run-time entities, reflective applications tend to focus on static abstractions, like classes and methods, rather than objects. This is phenomenon we call the object paradox, which makes developers less effective by drawing their attention away from run-time objects. To counteract this phenomenon, we propose a purely object-centric approach to reflection. Reflective mechanisms provide object-specific capabilities as another feature. Object-centric reflection proposes to turn this around and put object-specific capabilities as the central reflection mechanism. This change in the reflection architecture allows a unification of various reflection mechanisms and a solution to the object paradox. We introduce Bifr\"ost, an object-centric reflective system based on first-class meta-objects. Through a series of practical examples we demonstrate how object-centric reflection mitigates the object paradox by avoiding the need to reflect on static abstractions. We survey existing approaches to reflection to establish key requirements in the domain, and we show that an object-centric approach simplifies the meta-level and allows a unification of the reflection field. We demonstrate how development itself is enhanced with this new approach: talents are dynamically composable units of reuse, and object-centric debugging prevents the object paradox when debugging. We also demonstrate how software analysis is benefited by object-centric reflection with Chameleon, a framework for building object-centric analysis tools and MetaSpy, a domain-specific profile

Ginkgo: A Modern Linear Operator Algebra Framework for High Performance Computing

© ACM, YYYY. This is the author's version of the work "Anzt, H., Cojean, T., Flegar, G., Göbel, F., Grützmacher, T., Nayak, P., ... & Quintana-Ortí, E. S. (2022). Ginkgo: A modern linear operator algebra framework for high performance computing. ACM Transactions on Mathematical Software (TOMS), 48(1), 1-33". It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in ACM Transactions on Mathematical Software, {VOL48, ISS 1, (MAR 2022)} http://doi.acm.org/10.1145/3480935"[EN] In this article, we present GINKGO, a modern C++ math library for scientific high performance computing. While classical linear algebra libraries act on matrix and vector objects, Gnswo's design principle abstracts all functionality as linear operators," motivating the notation of a "linear operator algebra library" GINKGO'S current focus is oriented toward providing sparse linear algebra functionality for high performance graphics processing unit (GPU) architectures, but given the library design, this focus can be easily extended to accommodate other algorithms and hardware architectures. We introduce this sophisticated software architecture that separates core algorithms from architecture-specific backends and provide details on extensibility and sustainability measures. We also demonstrate GINKGO'S usability by providing examples on how to use its functionality inside the MFEM and deal.ii finite element ecosystems. Finally, we offer a practical demonstration of GINKGO'S high performance on state-of-the-art GPU architectures.This work was supported by the "Impuls und Vernetzungsfond of the Helmholtz Association" under grant VH-NG-1241. G. Flegar and E. S. Quintana-Orti were supported by project TIN2017-82972-R of the MINECO and FEDER and the H2020 EU FETHPC Project 732631 "OPRECOMP". This researchwas also supported by the Exascale Computing Project (17-SC-20-SC), a collaborative effort of the U.S. Department of Energy Office of Science and the National Nuclear Security Administration. The experiments on the NVIDIA A100 GPU were performed on the HAICORE@KIT partition, funded by the "Impuls und Vernetzungsfond" of the Helmholtz Association. The experiments on the AMD MI100 GPU were performed on Tulip, an early-access platform hosted by HPE.Anzt, H.; Cojean, T.; Flegar, G.; Göbel, F.; Grützmacher, T.; Nayak, P.; Ribizel, T.... (2022). Ginkgo: A Modern Linear Operator Algebra Framework for High Performance Computing. ACM Transactions on Mathematical Software. 48(1):1-33. https://doi.org/10.1145/348093513348

Design and implementation of a scalable domain specific language foundation for ScaFi with Scala 3

In the field of macroprogramming, one of the prominent engineering techniques is aggregate computing, which allows the definition of the overall behavior of a network of devices or agents through a single program, called the aggregate program. ScaFi is an aggregate programming framework that comprises an internal Domain Specific Language (DSL) written in Scala 2 with supporting components for simulation, visualization, and execution of aggregate systems, based on the Field Calculus formal language and computational model. Recently, a new formal language and computational model called Exchange Calculus has been proposed, extending the expressiveness of Field Calculus while simplifying its set of primitive constructs. In the meantime, Scala 2 has been succeeded by Scala 3, which introduces a relevant set of new features and improvements over its predecessor. These two novelties have promoted the development of a new ScaFi, called ScaFi-XC, entirely redesigned to be formally based on Exchange Calculus and to make the best use of its new host language, Scala 3, enhancing the original ScaFi with a more expressive and flexible DSL. This thesis presents the design and implementation of ScaFi-XC, focusing on the core DSL and associated components such as the engine and the simulator. In conclusion, ScaFi-XC has been successfully implemented and tested, delivering the expected results and fulfilling the requirements of the stakeholders, which are mainly the researchers and developers of the original ScaFi. Nevertheless, there is still work to be done to have a complete and stable version of the framework, such as porting all the support modules and improving the simulator

A qualitative assessment of modularity in CaesarJ components based on implementations of design patterns

Tese de Mestrado em Engenharia InformáticaThe advent of the Aspect-Oriented Programming (AOP) paradigm brought new features and mechanisms to support the separation of crosscutting concerns, in order to develop programs with higher modularity and consequently, higher reuse. As the paradigm matures, various aspectoriented programming languages appeared that propose varying ways to realize the paradigm’s concepts. CaesarJ is one of those aspect-oriented languages. While the majority of practical studies on AOP languages focused on the AspectJ language, the characteristics of other languages such as CaesarJ remain to be explored. The lack of research on the utilization of CaesarJ in concrete cases leads to the existence of few case studies from which to draw considerations about their strengths and shortcomings. In the past, implementations of design patterns have been used for the demonstration of the characteristics of the programming languages used to implement them. This dissertation follows a similar approach to assess CaesarJ’s support for modularity and reuse by producing CaesarJ design patterns implementations and subjecting those implementations to a qualitative analysis. This dissertation presents CaesarJ implementations of eleven Gang-of-Four pattern that serve as the basis for a qualitative analysis of the modularity degree CaesarJ enables for each pattern. A distinction is made between four levels of module reuse that the implementations support, in order to differentiate between the several levels of reuse achieved. A comparison is drawn to analogue design pattern implementations in AspectJ. Finally, general guidelines for the implementation of CaesarJ components are described

Structural abstraction: a mechanism for modular program construction

Abstraction mechanisms in programming languages aim to allow orthogonal pieces of functionality to be developed separately; complex software can then be constructed through the composition of these pieces. The effectiveness of such mechanisms lies in their support for modularity and reusability: The behavior of a piece of code should be reasoned about modularly---independently of the specific compositions it may participate in; the computation of a piece of code should allow specialization, so that it is reusable for different compositions. This dissertation introduces structural abstraction: a mechanism that advances the state of the art by allowing the writing of highly reusable code---code whose structure can be specialized per composition, while maintaining a high level of modularity. Structural abstraction provides a disciplined way for code to inspect the structure of its clients in composition, and declare its own structure accordingly. The hallmark feature of structural abstraction is that, despite its emphasis on greater reusability, it still allows modular type checking: A piece of structurally abstract code can be type-checked independently of its uses in compositions---an invaluable feature for highly reusable components that will be statically composed by other programmers. This dissertation introduces two structural abstraction techniques: static type conditions, and morphing. Static type conditions allow code to be conditionally declared based on subtyping constraints. A client of a piece of code can configure a desirable set of features by composing the code with types that satisfy the appropriate subtyping conditions. Morphing allows code to be iteratively declared, by statically reflecting over the structural members of code that it would be composed with. A morphing piece of code can mimic the structure of its clients in composition, or change its shape according to its clients in a pattern-based manner. Using either static type conditions or morphing, the structure of a piece of code is not statically determined, but can be automatically specialized by clients. Static type conditions and morphing both guarantee the modular type-safety of code: regardless of specific client configurations, code is guaranteed to be well-typed.Ph.D.Committee Chair: Yannis Smaragdakis; Committee Member: Oege de Moor; Committee Member: Richard LeBlanc; Committee Member: Santosh Pande; Committee Member: Spencer Rugabe

Towards a clinical trial ontology using a concern-oriented approach

Not yet availablePer ridurre i costi e migliorare la qualita\u27 della ricerca nei trial clinici (CT) e\u27 necessario un approccio piu\u27 sistematico all\u27automazione dei CT per rinforzare l\u27interoperabilita\u27 a vari livelli del processo di ricerca. Per questo scopo e\u27 stato sviluppato un modello concettuale di CT. Alla base di ogni approccio di modellizzazione ci sono criteri di partizione che ci permettono di dominare la complessita\u27 dell\u27universo da modellare. In questo rapporto noi introduciamo un metodo originale di analisi basato sui concern degli stakeholder per partizionare il domino concettuale dei CT in sotto-domini orientati agli stakeholder. Le rappresentazioni mentali degli stakeholder relative a ciascun concern sono identificati come cluster di concetti collegati ad altri concetti. Noi consideriamo ciascun cluster come una base razionale per il relativo concern. I concetti trovati nelle basi razionali popolano l\u27universo del discorso specifico per ogni stakeholder e compongono il vocabolario degli stakeholder. Alcuni concetti sono condivisi con altri stakeholder, mentre altri sono specifici di uno stakehoder; alcuni concetti sono specifici dei CT, mentre altri sono concetti medici o generali. In questo modo un\u27ontologia orientata ai concern per i CT puo\u27 essere creata. Il metodo e\u27 illustrato utilizzando i criteri di selezione dei soggetti, una componente di un progetto di CT, ma puo\u27 essere usato per ogni altra componente del protocollo del CT. La tassonomia del vocabolario dei concetti dei CT e la rete delle relative basi razionali ci fornisce una struttura possibile per lo sviluppo del software specialmente se si adotta una soluzione basata su architetture orientate ai servizi

Structuring fault-tolerant object-oriented systems using inheritance and delegation

PhD ThesisMany entities in the real world that a software system has to interact with, e.g., for controlling or monitoring purposes, exhibit different behaviour phases in their lifetime, in particular depending on whether or not they are functioning correctly. That is, these entities exhibit not only a normal behaviour phase but also one or more abnormal behaviour phases associated with the various faults which occur in the environment. These faults are referred to as environmental faults. In the object-oriented software, real-world entities are modeled as objects. In a classbased object-oriented language, such as C++, all objects of a given class must follow the same external behaviour, i.e., they have the same interface and associated implementation. However this requires that each object permanently belong to a particular class, imposing constraints on the mutability of the behaviour for an individual object. This thesis proposes solutions to the problem of finding means whereby objects representing real-world entities which exhibit various behaviour phases can make corresponding changes in their own behaviour in a clear and explicit way, rather than through status-checking code which is normally embedded in the implementation of various methods. Our proposed solution is (i) to define a hierarchy of different subclasses related to an object which corresponds to an external entity, each subclass implementing a different behaviour phase that the external entity can exhibit, and (ii) to arrange that each object forward the execution of its operations to the currently appropriate instance of this hierarchy of subclasses. We thus propose an object-oriented approach for the provision of environmental fault tolerance, which encapsulates the abnormal behaviour of "faulty" entities as objects (instances of the above mentioned subclasses). These abnormal behaviour variants are defined statically, and runtime access to them is implemented through a delegation mechanism which depends on the current phase of behaviour. Thus specific reconfiguration changes at the level of objects can be easily incorporated to a software system for tolerating environmental faults

An Extension Interface Concept for Multilayered Applications

Extensibility is an important feature of modern software applications. In the context of business applications it is one of the major selection criteria from the customer perspective. Software extensions enable developers to integrate new features to a software system for supporting new requirements. However, there are many open challenges concerning the software provider and the extension developer. A software provider must provide extension interfaces that define the software artifacts of the base application that are allowed to be extended, where and when the extension code will run, and what resources of the base application an extension is allowed to access. While concepts for such interfaces are still a challenging research topic for ``traditional'' software constructed using a single programming language, they are completely missing for complex systems consisting of several abstraction layers. In addition, state-of-the-art approaches do not support providing different extension interfaces for different stakeholders. To develop an extension for a certain software system, the extension developer has to understand what extension possibilities exist, which software artifacts provide these possibilities, the constraints and dependencies between the extensible software artifacts, and how to correctly implement an extension. For example, a simple user interface extension in a business application can require a developer to consider extensible artifacts from underlying business processes, database tables, and business objects. In commercial applications, extension developers can depend on classical means like application programming interfaces, frameworks, documentation, tutorials, and example code provided by the software provider to understand the extension possibilities and how to successfully implement, deploy, and run an extension. For complex multilayered applications, relying on such classical means can be very hard and time-consuming for the extension developers. In integrated development environments, various program comprehension tools and approaches have helped developers in carrying out development tasks. However, most of the tools focus on the code level, lack the support for multilayered applications, and do not particularly focus on extensibility. In this dissertation I aim to provide better means for defining, implementing, and consuming extension interfaces for multilayered applications. I claim that explicit extension interfaces are required for multilayered applications and they are needed for simplifying the implementation (i.e., the concrete realization) and maintainability of extension interfaces on the side of the software provider as well as the consumption of these interfaces by the extension developers. To support this thesis, I first analyze problems with extension interfaces from the perspectives of both the software provider through an example business application and an analysis of a corpus of software systems. I then analyze the problems with the consumption of extension interfaces (i.e., extension development) through a user study involving extension developers performing extension development tasks for a complex business application. Next, I present XPoints, an approach and a language for the specification of extension possibilities for multilayered applications. I develop an instantiation of XPoints evaluate it against current state-of-the-art works and its usability through a user study. I finally show how XPoints can be applied to simplify the extension development through the implementation of a recommender system for extension possibilities for multilayered applications. The advantages of the recommender system are illustrated through an example as well through a comparison between the current state-of-the-art tools for program comprehension. Topics like extension validation, monitoring, and conflict detection are left for future work