Uwe Hohenstein

• Doctor of Engineering
• Siemens

The digital transformation of manufacturing-Industry 4.0-has sparked interest in digital twins, which are virtual replicas of physical assets. One popular structure for these digital twins is the Asset Administration Shell (AAS), which has been widely adopted. However, the large-scale conversion of asset data into AAS structures is not trivial, par...

Model transformations are central to model-driven software development. Applications of model transformations include creating models, handling model co-evolution, model merging, and understanding model evolution. In the past, various (semi-)automatic approaches to derive model transformations from meta-models or from examples have been proposed. T...

Model transformations play a fundamental role in model-driven software development. They can be used to solve or support central tasks, such as creating models, handling model co-evolution, and model merging. In the past, various (semi-)automatic approaches have been proposed to derive model transformations from meta-models or from examples. These...

Model transformations play a fundamental role in model-driven software development. They can be used to solve or support central tasks, such as creating models, handling model co-evolution, and model merging. In the past, various (semi-)automatic approaches have been proposed to derive model transformations from meta-models or from examples. These...

Whenever a new database technology appears, several comparisons also come up to attest that the new database technology is better than the traditional relational one. Even more, an outstanding performance is shown quite often by conducting performance comparisons. This paper attempts to illustrate that these performance comparisons should be taken...

Literature review studies are essential and form the foundation for any type of research. They serve as the point of departure for those seeking to understand a research topic, as well as, helps research communities to reflect on the ideas, fundamentals, and approaches that have emerged, been acknowledged, and formed the state-of-the-art. In this p...

Data and access to data are becoming more and more a product or service to be sold. In order to deal with data access, this paper presents a marketplace for trading data. Within the marketplace, producers can present their offerings for data access and algorithms, whereas consumers are able to browse through the offerings, to subscribe to correspon...

Software architecture can be seen as a set of architectural design decisions. These decisions, especially their rationale, play an important role in understanding software systems and constraints that are imposed on future design decisions. Documenting and managing these design decisions takes a lot of effort and is therefore often neglected by sof...

Software architecture can be seen as a set of architectural design decisions (ADDs) that shape the resulting software solution. To make an ADD, stakeholders follow some organization- or team-specific group decisions making process. In this study, we aimed to advance the understanding of how ADDs are made by observing and learning how architects han...

The area of storage solutions is becoming more and more heterogeneous. Even in the case of relational databases, there are several offerings, which differ from vendor to vendor and are offered for different deployments like on-premises or in the Cloud, as Platform-as-a-Service (PaaS) or as a special Virtual Machine on the Infrastructure-as-a-Servic...

In large software engineering projects, designing software systems is a collaborative decision-making process where a group of architects and developers make design decisions on how to address design concerns by discussing alternative design solutions. For the decision-making process, involving appropriate individuals requires objectivity and aware...

The need to explicitly document design decisions has been emphasized both in research and in industry. To address design concerns, software architects and developers implicitly capture design decisions in tools such as issue management systems. These design decisions are not explicitly labeled and are not integrated with the architecture knowledge...

The design and development of sustainable software systems require software architects to consider a variety of architectural solutions and their trade-offs. With the frequent introduction of new architectural methods and software solutions, as well as, due to time-to-market constraints faced by software architects, considering even a subset of alt...

Multi-tenancy is an architectural style to share resources amongst several tenants. It is an important facet of Cloud Computing and often considered a key element to make Software-as-a-Service (SaaS) profitable. Indeed, SaaS providers adopt multi-tenancy to optimize resource usage and to save operational costs. While literature often discusses how...

The need to support a software architect's day-today activities through efficient tool support has been highlighted both in research and industry. However, managing enter-prises' Architectural Knowledge (AK) to support scenarios such as decision making, what-if analysis, and collaboration during the execution of large industrial projects is still a...

Model-driven development (MDD) and aspect-oriented programming (AOP) are two very different paradigms, having in common that they both aim at increasing development efficiency. In order to investigate their benefits and liabilities, we compared both in context of a case study on an industrial-grade software system, the Open SOA platform. Already ha...

The goal of the study City2.e was the development of a concept for public and semi-public charging infrastructure for urban electric vehicle drivers. Moreover, the future potential and the boundary conditions of a change from a mobility based ownership to a mobility based one that uses fully integrated transport association should be investigated....

This case study compares two different technologies - model-driven development (MDD) and aspectoriented programming (AOP) - both trying to avoid redundant code, but with very different approaches. A real industrial software system, the OpenSOA platform, which had already applied a model-driven XML/XSL-T approach, is used as the basis for implementa...

Content centric storage refers to a paradigm where data objects are accessed by applications through information about their content, rather than their path in a hierarchical structure. Applications are relieved from having knowledge about the data store organization or the place in a (physical) storage hierarchy. Instead, applications can use meta...

Content-centric storage represents an approach for handling large amounts of data. It is one of the innovations pursued by the VISION Cloud project. The goal of the VISION Cloud project is the development of an industry grade storage system using cloud technology. The envisaged use of the VISION Cloud involves the storage and management of millions...

One of the important aspects of Cloud computing is certainly the pay-per-use model; users have to pay only for those resources they are actively using, on a timely basis. This model paired with principally infinite resources promises to run applications at lower costs, arguably. This paper demonstrates by means of two case studies that applications...

Novel approaches in resource provisioning and releasing grew out of cloud computing. Nevertheless, the management of resource pools still needs manual configuration to react on load changes. The presented idea is to procure user-data based on Social Web applications and to use this information for forecasting load progression. Thereby data of geoca...

Nowadays, cloud computing promises to supply a theoretically infinite resource amount, while enabling instance elasticity. However, using extra capacity requires organizational activities and leads to costs. To keep this overhead minimal, adding and releasing resources need to be well-scheduled. Therefore, it is inevitable to prepare an appropriate...

This article reports on the usage of aspect-orientation in an industrial project, which means that aspects are an active part of a real software product. Moreover, aspect-orientation, in particular the language AspectJ, is used to overcome several critical problems. Those problems are well motivated and discussed in detail. Some of them are hard to...

The Java programming language offers several basic constructs for concurrent programming. Despite covering everything needed from a functional point of view, the constructs are difficult to use since they require a lot of infrastructural statements besides the real logic. This makes concurrent programming errorprone and difficult to reuse. It seems...

This article reports on the usage of aspect-orientation in an industrial project, which means that aspects are an active part of a real software product. Moreover, aspect-orientation, in particular the language AspectJ, is used to overcome several critical problems. Those problems are well motivated and discussed in detail. Some of them are hard to...

With cloud computing, the general idea is to deploy applications and services in the cloud, at some cloud provider's facilities. But as with traditional software applications, business demands still exist including legal, privacy, cost and technical issues. These demands can prohibit the deployment of the entire software in a cloud provider space....

This work reports on problems we had with persistence frameworks in an industrial project. Most problems occurred when replacing the persistence framework Hibernate with OpenJPA. Such a substitution basically means exchanging API calls and dealing with functional differences. But the replacement involved challenging problems since some important Hi...

Aspect-orientation handles crosscutting concerns in an adequate manner. It also promises a high potential for reuse due to a higher level of modularization since crosscutting concerns can better be modularized in aspects. This paper confirms higher reuse by presenting an AspectJ-based reuse approach. A collection of reusable aspects, e.g., for issu...

Durch die hohe Dynamik im Bereich des Cloud Computings entstehen neues Potenzial, aber auch Risiken bezüglich existierender und neuer Anwendungen. Ein wichtiger Punkt bei der Nutzung von Cloud Computing Ressourcen ist Cloud Storage. Unter Cloud Storage werden Datenspeicher subsumiert, die in unterschiedlichen Konfigurationen von Cloud Computing Bet...

Cloud Computing ist in aller Munde. Es existieren bereits Firmen und Anwendungen, die von Clouds profitieren (z.B. Smugmug, Twitter, Slideshare etc.). Für den Einsatz in Unternehmen ist hingegen deren Nutzung noch nicht Standard. Unter anderem ist offen, wie sich eine Cloud bzw. die Produkte der Cloud Provider als Datenspeicher für Standardanwendun...

Server-sided applications often use a persistence system for storing and managing their data in a database. Such a system has become complex and includes but is not limited to a database system, drivers, connection pools, query languages, the mapping between application logic and a database data model and it involves the optimization of resources....

Aspect-orientation (AO) is a recent technology for handling crosscutting concerns in a structured and modular manner. In spite of being considered useful, researchers often complain that industry is not widely adopting AO concepts and technologies in commercial projects. This paper reports on real usage of aspect-orientation in an industrial projec...

Server applications often use a relational database management system (RDBMS) for storing and managing their data. Storage and management is not limited to the RDBMS itself, but involves also other software forming a persistence system. Such system has become complex. Besides the RDBMS it includes drivers, connection pools, query languages, the map...

This paper demonstrates the power of aspect-orientation by implementation the EJB3.0 persistence framework. Our approach has advantages over existing mapping tools: Flexibility is higher as the functionality can be freely implemented and extended to user's needs.

Database-internal statistics are very important for cost-based query optimizers. Only if an optimizer has accurate statistical information about data, it provides excellent execution plans for queries; if those statistics are out of date, then queries will be badly optimized and performance suffers. Unfortunately, a lot of database systems currentl...

This paper presents a proposal for convincing industry of aspect-orientation, as it has been applied within Siemens. The proceeding stresses on the immediate benefits and ease of usage. Starting with an existing application, we show how to improve the performance and how to extend the behavior with only a few code modifications by bringing aspect-o...

To convince the industry to use aspect-oriented programming techniques we have to defeat the prejudice against this paradigm. One mean to achieve this are studies proving the benefits of AO and disproving the retentions against it. We describe a small comparative study comparing one OO with three AO languages. The study results and the experience w...

This paper presents a comfortable and customizable persistence framework that supports the access of relational databases from Java applications. In order to keep the effort for implementation low, we show how to benefit from aspect-orientation. The framework has advantages over existing mapping tools: Flexibility is higher as the functionality can...

In order to use files in database federations, we propose to migrate file data into a relational database. Integrating the database in a federation is then well-understood. This procedure has the advantage that a ,,real" database is handled supporting transactions and SQL; files obtain a high-level interface for free. This paper presents a specific...

Data migration between relational and object-oriented database systems is useful whenever relational data is needed in new object-oriented environments. However, implementing migration programs, i.e. converting and loading legacy data into the new database system, is cumbersome and must be done for each pair of databases manually. This paper presen...

In order to provide database-like features for files, particularly for searching in Web data, one solution is to migrate file data into a relational database. Having stored the data, the capabilities of SQL can be used for querying, provided, the data has been given some structure. To this end, an adapter must be implemented that converts data from...

A comprehensive, specification-based approach for building database federations is introduced that supports an integrated ODMG2.0 conforming access to heterogeneous data sources seamlessly done in C++. The approach is centered around several generators. A first set of generators produce ODMG adapters for local sources in order to homogenize them. E...

After the successful first International Workshop on Engineering Federated Database Systems (EFDBS'97) in Barcelona in June 1997 [CEH+ 97], the goal of this second workshop was to bring together researchers and practitioners interested in various issues in the development of federated information systems, whereby the scope has been extended to cove...

This paper deals with generating interfaces to files. The presented approach consists of two main parts: first, describing the file structure in an object-oriented manner, and second, manipulating the files by means of either SQL or ODMG 2.0 object manipulation and querying. The principle of the approach is centered around a powerful specification...

Due to the increasing relevance of object-oriented database systems, special benchmarks have been developed in the past in order to analyze performance. The benchmarks show unanimously that object-oriented systems are excellently suited for applications managing complex structures. Particularly, those database systems provide a higher performance t...

This paper presents a database interface for C++ that provides an adequate and uniform coupling to different kinds of database management systems. An extended Entity-Relationship approach which is married to object-oriented features is used to provide a common modelling basis. The concepts of the data model are directly reflected by the interface t...

This paper introduces a comprehensive, specification-based approach to database federation, supporting an integrated ODMG-93 conforming access to object-oriented and relational databases. Central point is a set of intuitive specification languages. These languages allow defining ODMG-93 views of existing databases, and building system spanning fede...

Due to the increasing relevance of object-oriented database systems, special benchmarks have been developed in the past in order to analyze performance. The benchmarks show unanimously that object-oriented systems are excellently suited for applications managing complex structures. In particular, these database systems provide a higher performance...

Semantic enrichment is a process that upgrades the semantics of databases. Usually, this is done by remodelling database schemas in a higher data model in order to explicitly express semantics that is implicit in the data. We use the ODMG-93 standard for objectoriented database systems to this end. Hence relational database schemas are transformed...

Aufgrund der zunehmenden Relevanz von objektorientierten Datenbanksystemen sind in der Vergangenheit spezielle Benchmarks zur Beurteilung ihres Leistungsvermögens entwickelt worden. Die Benchmarks zeigen einhellig, daß objektorientierte Systeme für viele Applikationen mit komplex vernetzten Strukturen hervorragend geeignet sind und eine höhere Perf...

Das Buch ist ein umfassender und aktueller, bereits den ODMG-Standard berücksichtigender Leitfaden für alle, die objektorientierte Datenbanksysteme professionell in ihrem Unternehmen einsetzen wollen. Es führt praxisorientiert und verständlich in die Konzepte, die Kriterien und Verfahren bei der Arbeit mit objektorientierten Datenbanksystemen ein....

This work presents a new approach to access existing relational databases from C++ programs in an easy and natural way. The coupling of both worlds makes use of data reverse engineering techniques. Semantics that is inherent to relational data is made explicit by using object-oriented concepts extensively. Relationships and subtypes are expressed d...

Ziel der funktionalen Evaluierung ist es, festzustellen, welche Funktionalität die nach der Vorauswahl verbliebenen ODBMSe im einzelnen bieten und wie sich die Konzepte für die Applikationsentwicklung einsetzen lassen. Dazu werden im wesentlichen die Systemhandbücher herangezogen, die — im Gegensatz zu vielen Hochglanzbroschüren — eine technische B...

Die Auswahl eines objektorientierten Datenbanksystems hat eine langfristige Investition zur Folge, die sorgfältig vorbereitet werden sollte. Denn mit den Fähigkeiten und der Performance des Datenbanksystems stehen und fallen das Design und die Leistungsfähigkeit der gesamten Anwendung. Eine an den Anforderungen der Anwendung ausgerichtete Evaluieru...

Der Markt für objektorientierte Datenbanksysteme hat in den letzten Jahren eine rasante Entwicklung erfahren. Inzwischen werden mehr als ein Dutzend verschiedene Systeme angeboten, die sich hinsichtlich Leistungsmerkmale und Performance stark unterscheiden. Die Mehrheit der Produkte kommt aus den USA. Daneben sind aber auch einige europäische Anbie...

Objektorientierung ist seit einigen Jahren das Schlagwort in der modernen Software-Entwicklung. Mit dem rasanten Aufschwung der Computerindustrie und der steigenden Komplexität von Software-Lösungen haben sich die Kosten für die Erstellung und Wartung von Softwaresystemen stark erhöht. Objektorientierte Techniken stellen die geeigneten Mittel zur V...

Ziel der Vorauswahl ist es, die Menge der in Frage kommenden ODBMSe auf zwei oder drei Systeme einzuschränken und damit den Aufwand für den gesamten Evaluierungsprozeß in Grenzen zu halten. Gleichzeitig dient die Vorauswahl dazu, einen Überblick über den ODBMS-Markt zu gewinnen und erste Kontakte zu den Herstellern aufzubauen.

Objektorientierte Datenbanksysteme werden häufig in Anwendungsbereichen eingesetzt, die besonders hohe Anforderungen an die Leistungsfähigkeit des Datenbanksystems stellen. Oftmals hängt dabei der Erfolg oder Mißerfolg einer Anwendung unmittelbar von der Performance des verwendeten Datenbanksystems ab. Bevor die endgültige Entscheidung für den Eins...

Das Ziel dieses Kapitels ist es, ein Grundverständnis für Objektorientierte Datenbanksystemeksysteme (ODBMSe) zu wecken, das notwendig ist, urn ein objektorientiertes Datenbanksystem untersuchen, beurteilen und letztendlich auswählen zu können. Dazu werden die Basiskonzepte objektorientierter Datenbanksysteme erläutert.

Zum Abschluß des Buches werden zwei Fallstudien zur Auswahl und Bewertung von objektorientierten Datenbanksystemen vorgestellt. Mit ihrer Hilfe soll die in den vorhergehenden Kapiteln beschriebene Vorgehensweise zur Evaluierung von ODBMSen veranschaulicht werden. Die beiden Fallstudien haben ihren Ursprung in Projekten aus der Industrie, in denen O...

Semantische Anreicherung ist ein Prozeß, der die implizit in existierenden Datenbanken vorliegende Semantik explizit macht. Üblicherweise erfolgt die Anreicherung durch eine Transformation des Datenbankschemas in ein semantisch reichhaltigeres Datenmodell. Dabei werden die höheren Modellierungskonzepte, insbesondere Beziehungen und Subtypen, zur Ex...

Interoperability is a recent technology that meets the needs of new applications requiring access to several heterogeneous databases. In this context, it is important to detect the meaning of data in the various databases. Semantic enrichment is a process that makes inherent semantics explicit by transforming database schemas into a higher data mod...

This paper gives a comprehensive overview of the associative query facilities of commercial object-oriented database systems. We introduce general concepts of query languages, and analyse the query facilities of the systems. The analysis leads to a classification of query languages, precisely differentiating the capabilities. Further aspects concer...

A C++ interface is presented that provides an adequate coupling to relational database systems dispensing with embedded SQL approaches. The interface reaps the benefits of an extended Entity-Relationship approach having powerful modelling features. The concepts of the data model are directly reflected by the interface thereby providing an abstract...

Die formalen Definitionen der Datenbank-Signatur und des allgemeinen Kalküls bilden das theoretische Fundament der Transformationssemantik relativ zum Relationenmodell, die im auf den konzeptionellen Datenbankentwurf folgenden logischen Entwurf bedeutungsvoll wird. In dieser Phase ist eine konkrete Modellierung in einem semantischen Datenmodell (z....

Der Entity-Relationship-Ansatz zeichnet sich wie kaum ein anderes Datenmodell durch eine Vielzahl an Anfragesprachen unterschiedlicher Couleur aus, die eine einfachere und natürlichere Formulierung von Anfragen erlauben, als sie beispielsweise in relationalen Anfragesprachen möglich ist. Bereits die ersten Sprachentwürfe wie CABLE [Sho78] oder CLEA...

Zur Unterstützung des konzeptionellen Entwurfs von Datenbanken existiert bereits eine große Vielfalt an Datenmodellen. Jedes dieser Datenmodelle stellt formale Konzepte bereit, mit denen sich der durch eine konkrete Anwendung gegebene Ausschnitt der realen Welt abstrakt modellieren läßt. Besonderer Wert wird auf ein möglichst hohes Abstraktionsverm...

Die Syntax und Semantik des im vorangegangenen Kapitel vorgestellten EER-Kalküls soll in diesem Kapitel formal definiert werden. Um auch für andere Datenmodelle verwendet werden zu können, liegt dem Kalkül der Begriff einer allgemeinen Datenbank-Signatur (Definition 4.21) zugrunde. Somit ist der Kalkül für alle Datenmodelle definiert, die in diesen...

In diesem Kapitel stellen wir kurz formale Notationen für die folgenden Kapitel zusammen.

Im Vordergrund dieses Buches stand ein durchgängiger, logik-orientierter Formalismus zur vollständigen semantischen Definition eines Datenmodells bestehend aus einem erweiterten Entity-Relationship-Modell, einem Kalkül und einer darauf aufbauenden Anfragesprache.