Frank Leymann

Frank Leymann
Universität Stuttgart · Institute of Architecture of Application Systems

Prof. Dr. Dr. h. c.

About

811
Publications
144,269
Reads
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26,122
Citations
Introduction
Quantum Computing, Scientific Director of the quantum computing project PlanQK (German lighthouse project)

Publications

Publications (811)
Preprint
Full-text available
The algorithm of Shor for prime factorization is a hybrid algorithm consisting of a quantum part and a classical part. The main focus of the classical part is a continued fraction analysis. The presentation of this is often short, pointing to text books on number theory. In this contribution, we present the relevant results and proofs from the theo...
Article
Full-text available
Today’s quantum computers are limited in their capabilities, e.g., the size of executable quantum circuits. The Quantum Approximate Optimization Algorithm (QAOA) addresses these limitations and is, therefore, a promising candidate for achieving a near-term quantum advantage. Warm-starting can further improve QAOA by utilizing classically pre-comput...
Conference Paper
Infrastructure-as-Code (IaC) technologies are used to automate the deployment of cloud applications. They promote the usage of code to define and configure the IT infrastructure of cloud applications allowing them to benefit from conventional software development practices, which facilitates the rapid deployment of new versions of application infra...
Book
Infrastructure-as-Code (IaC) technologies are used to automate the deployment of cloud applications. They promote the usage of code to define and configure the IT infrastructure of cloud applications allowing them to benefit from conventional software development practices, which facilitates the rapid deployment of new versions of application infra...
Article
Function‐as‐a‐Service (FaaS) is a cloud service model enabling to implement serverless applications for a variety of use cases. These range from scheduled calls of single functions to complex function orchestrations executed using orchestration services such as AWS step functions. However, since the available function orchestration technologies var...
Article
Full-text available
Abstract Quantum computing promises breakthroughs in various application areas, such as machine learning, chemistry, or simulations. However, today’s quantum computers are error‐prone and have limited capabilities. This leads to various challenges when developing and executing quantum algorithms, for example, the mitigation of occurring errors or t...
Article
Full-text available
Abstract As quantum computers are based on the laws of quantum mechanics, they are capable of solving certain problems faster than their classical counterparts. However, quantum algorithms with a theoretical speed‐up often assume that data can be loaded efficiently. In general, the runtime complexity of the loading routine depends on (i) the data e...
Chapter
Quantum computers have the potential to solve certain problems faster than classical computers. However, the computations that can be executed on current quantum devices are still limited. Hybrid algorithms split the computational tasks between classical and quantum computers circumventing some of these limitations. Therefore, they are regarded as...
Chapter
For very specific problems, quantum advantage has recently been demonstrated. However, current NISQ computers are error-prone and only support small numbers of qubits. This limits the executable circuit size of an implemented quantum algorithm. Due to this limitation, it is important that compiled quantum circuits for a specific quantum computer ar...
Preprint
Full-text available
With recent advances in the development of more powerful quantum computers, the research area of quantum software engineering is emerging, having the goal to provide concepts, principles, and guidelines to develop high-quality quantum applications. In classical software engineering, lifecycles are used to document the process of designing, implemen...
Chapter
Quantum computers have been significantly advanced in recent years. Offered as cloud services, quantum computers have become accessible to a broad range of users. Along with the physical advances, the landscape of technologies supporting quantum application development has also grown rapidly in recent years. However, there is a variety of tools, se...
Chapter
Most of today’s deployment automation technologies enable the deployment of distributed applications in distributed environments, whereby the deployment execution is centrally coordinated either by a central orchestrator or a master in a distributed master-workers architectures. However, it is becoming increasingly important to support use cases wh...
Book
Function-as-a-Service (FaaS) is a cloud service model enabling developers to offload event-driven executable snippets of code. The execution and management of such functions becomes a FaaS providerâs responsibility, therein included their on-demand provisioning and automatic scaling. Key enablers for this cloud service model are FaaS platforms, e.g...
Article
Full-text available
The execution of a quantum algorithm typically requires various classical pre- and post-processing tasks. Hence, workflows are a promising means to orchestrate these tasks, benefiting from their reliability, robustness, and features, such as transactional processing. However, the implementations of the tasks may be very heterogeneous and they depen...
Chapter
Pattern languages are well-established in the software architecture community. Many different aspects of creating a software architecture are addressed by such languages. Thus, several pattern languages have to be considered when building a particular architecture. But these pattern languages are isolated, i.e. it is hard to determine the relevant...
Chapter
As quantum computers are becoming real, they have the inherent potential to significantly impact many application domains. In this paper we outline the fundamentals about programming quantum computers and show that quantum programs are typically hybrid consisting of a mixture of classical parts and quantum parts. With the advent of quantum computer...
Preprint
Quantum applications are most often hybrid, i.e. they are not only made of implementations of pure quantum algorithms but also of classical programs as well as workflows and topologies as key artifacts, and data they process. Since workflows and topologies are referred to as orchestrations in modern terminology (but with very different meaning), tw...
Article
Full-text available
Function-as-a-Service (FaaS) is a cloud service model enabling developers to offload event-driven executable snippets of code. The execution and management of such functions becomes a FaaS provider’s responsibility, therein included their on-demand provisioning and automatic scaling. Key enablers for this cloud service model are FaaS platforms, e.g...
Chapter
The growing trend of integrating software processes and the physical world created new paradigms, such as, the Internet of Things and Cyber-Physical Systems. However, as applications of these paradigms are rolled out, the management of their software and hardware components becomes a challenge, e.g., an update of a mobile system must not only consi...
Chapter
Quantum computing can enable a variety of breakthroughs in research and industry in the future. Although some quantum algorithms already exist that show a theoretical speedup compared to the best known classical algorithms, the implementation and execution of these algorithms come with several challenges. The input data determines, for example, the...
Chapter
Patterns describe proven solutions for recurring problems. Typically, patterns in a particular domain are interrelated and can be organized in pattern languages. As real-world problems often require to combine patterns of multiple domains, different pattern languages have to be considered to address these problems. However, cross-domain knowledge a...
Preprint
Although historically the term serverless was also used in the context of peer-to-peer systems, it is more frequently associated with the architectural style for developing cloud-native applications. From the developer's perspective, serverless architectures allow reducing management efforts since applications are composed using provider-managed co...
Book
Microservice-based architectures (MSAs) gained momentum in industrial and research communities since finer-grained and more independent components foster reuse and reduce time to market. However, to come from the design of MSAs to running applications, substantial knowledge and technology-specific expertise in the deployment and integration of micr...
Chapter
The OASIS standard TOSCA provides a portable means for specifying multi-service applications and automating their deployment. Despite TOSCA is widely used in research, it is currently not supported by the production-ready deployment technologies daily used by practitioners, hence resulting in a gap between the state-of-the-art in research and the s...
Article
Full-text available
Implementing a gate-based quantum algorithm on a NISQ device has several challenges that arise from the fact that such devices are noisy and have limited quantum resources. Thus, various factors contributing to the depth and width as well as to the noise of an implementation of a gate-based algorithm must be understood in order to assess whether an...
Article
Full-text available
The establishment of digital humanities as a research field has shown that the use of computers as tools, but also the use of methods and techniques from computer science, can contribute enormously to research done in the humanities. Since quantum computers are expected to become generally available in the next few years, it is promising to use the...
Article
Full-text available
With the continuous growth of IT application systems, the complexity of architecture modeling and development increases. Patterns document proven solutions for recurring problems in an abstract and human readable manner. Within the domain of IT architectures, they should support the architecture modeling and development process. Due to the document...
Article
Full-text available
Traditional distributed transaction processing (TP) systems, such as replicated databases, faced difficulties in getting wide adoption for scenarios of enterprise integration due to the level of mutual trust required. Ironically, public blockchains, which promised to solve the problem of mutual trust in collaborative processes, suffer from issues l...
Article
Full-text available
Pattern languages as tools for solving problems based on interconnected, abstract, and proven solutions can offer valuable help to practitioners. But there is always the question of where to begin when a pattern language should be applied. Their authors often provide entry points, but these are usually only useful if one starts completely from scra...
Article
Full-text available
Emerging serverless computing technologies, such as function as a service (FaaS), enable developers to virtualize the internal logic of an application, simplifying the management of cloud-native services and allowing cost savings through billing and scaling at the level of individual functions. Serverless computing is therefore rapidly shifting the...
Article
Full-text available
In recent years, several technologies were developed enabling the automated provisioning and decommissioning of cloud applications. To reduce costs, these applications can be terminated and restarted on demand. However, as an application is terminated, its current application state, i.e., all application specific data is deleted along with the runn...
Article
Full-text available
In recent years, a plethora of deployment technologies evolved, many following a declarative approach to automate the delivery of software components. Even if such technologies share the same purpose, they differ in features and supported mechanisms. Thus, it is difficult to compare and select deployment automation technologies as well as to migrat...
Book
The OASIS standard TOSCA provides a portable means for specifying multi-service applications and automating their deployment. Despite TOSCA is widely used in research, it is currently not supported by the production-ready deployment technologies daily used by practitioners, hence resulting in a gap between the state-of-the-art in research and the s...
Preprint
Pattern languages are well-established in the software architecture community. Many different aspects of creating a software architecture are addressed by such languages. Thus, several pattern languages have to be considered when building a particular architecture. But these pattern languages are isolated, i.e. it is hard to determine the relevant...
Preprint
Implementing a quantum algorithm on a NISQ device has several challenges that arise from the fact that such devices are noisy and have limited quantum resources. Thus, various factors contributing to the depth and width as well as to the noise of an implementation of an algorithm must be understood in order to assess whether an implementation will...
Conference Paper
Blockchains are distributed ledgers that enable the disintermediation of collaborative processes and, at the same time, foster trust among partners. Modern blockchains support smart contracts, i.e., software deployed on the blockchain, and guarantee their repeatable, deterministic execution. Alas, blockchains and smart contracts lack standardizatio...
Chapter
Various technologies have been developed to automate the deployment of applications. Although most of them are not limited to a specific infrastructure and able to manage multi-cloud applications, they all require a central orchestrator that processes the deployment model and executes all necessary tasks to deploy and orchestrate the application co...
Book
Blockchains are distributed ledgers that enable the disintermediation of collaborative processes and, at the same time, foster trust among partners. Modern blockchains support smart contracts, i.e., software deployed on the blockchain, and guarantee their repeatable, deterministic execution. Alas, blockchains and smart contracts lack standardizatio...
Book
Various technologies have been developed to automate the deployment of applications. Although most of them are not limited to a specific infrastructure and able to manage multi-cloud applications, they all require a central orchestrator that processes the deployment model and executes all necessary tasks to deploy and orchestrate the application co...
Article
This article introduces the reader to a set of technologies that lay the foundation for a service-oriented integration of smart contracts into generic software applications, such as business processes or enterprise applications. Using a typical supply chain scenario, the article showcases the use of the Smart Contract Description Language (SCDL) to...
Book
Complex applications are typically composed of multiple components. In order to install these components all their dependencies need to be satisfied. Typically these dependencies are resolved, downloaded, and installed during the deployment time and in the target environment, e.g., using package manager of the operating system. However, under some...
Book
The term serverless is often used to describe cloud applications that comprise components managed by third parties. Like any other cloud application, serverless applications are often tightly-coupled with providers, their features, models, and APIs. As a result, when their portability to another provider has to be assessed, application owners must...
Book
The adoption of cloud computing combined with DevOps enables companies to react to new market requirements more rapidly and fosters the use of automation technologies. This influences the way software solutions are built, which is why the concept of cloud-native applications has emerged over the last few years to build highly scalable applications,...
Book
The automation of application deployment is critical because manually deploying applications is time-consuming, tedious, and error-prone. Several deployment automation technologies have been developed in recent years employing tool-specific deployment modeling languages. At the same time, the OASIS standard Topology Orchestration Specification for...
Book
This article introduces the reader to a set of technologies that lay the foundation for a service-oriented integration of smart contracts into generic software applications, such as business processes or enterprise applications. Using a typical supply chain scenario, the article showcases the use of the Smart Contract Description Language (SCDL) to...
Chapter
Since deployment automation technologies are heterogeneous regarding their supported features and modeling languages, selecting a concrete technology is difficult and can result in a lock-in. Therefore, we presented the Essential Deployment Metamodel (EDMM) in previous work that abstracts from concrete technologies and provides a normalized metamod...
Conference Paper
Today’s blockchain technologies focus mostly on isolated, proprietary technologies, yet there are application scenarios that ask for interoperability, e.g., among blockchains themselves or with external applications. This paper proposes the Smart Contract Locator (SCL) for the unambiguous identification of smart contracts over the Internet and acro...
Preprint
Function-as-a-Service (FaaS) is a cloud service model enabling developers to offload event-driven executable snippets of code. The execution and management of such functions becomes a FaaS provider's responsibility, hereby included their on-demand provisioning and automatic scaling. Key enablers for this cloud service model are FaaS platforms, e.g....
Book
With the ongoing advances in the area of cloud computing, Internet of Things, Industry 4.0, and the increasing prevalence of cyber-physical systems and devices equipped with sensors, the amount of data generated every second is rising steadily. Thereby, the gathering of data and the creation of added value from this data is getting easier and easie...
Book
Quantum computers are becoming real, and they have the inherent potential to significantly impact many application domains. We sketch the basics about programming quantum computers, showing that quantum programs are typically hybrid consisting of a mixture of classical parts and quantum parts. With the advent of quantum computers in the cloud, the...
Preprint
Full-text available
Quantum computing can enable a variety of breakthroughs in research and industry in the future. Although some quantum algorithms already exist that show a theoretical speedup compared to the best known classical algorithms, the implementation and execution of these algorithms come with several challenges. The input data determines, e.g., the requir...
Chapter
Full-text available
Declarative approaches for automating the deployment and configuration management of multi-component applications are on the rise. Many deployment technologies exist, sharing the same baselines for enacting declarative deployments, even if based on different languages for specifying multi-component applications. The Essential Deployment Metamodel (...
Chapter
Service composition is a popular approach for building software applications from several individual services. Using imperative workflow technologies, service compositions can be specified as workflow models comprising activities that are implemented, e.g., by service calls or scripts. While scripts are typically included in the workflow model itse...
Chapter
Architectural patterns assist in the process of architectural decision making as they capture architectural aspects of proven solutions. In many cases, the chosen patterns have system-wide implications on non-functional requirements such as availability, performance, and resilience. Ensuring compliance with the selected patterns is of vital importa...
Book
Declarative approaches for automating the deployment and configuration management of multi-component applications are on the rise. Many deployment technologies exist, sharing the same baselines for enacting declarative deployments, even if based on different languages for specifying multi-component applications. The Essential Deployment Metamodel (...
Book
Architectural patterns assist in the process of architectural decision making as they capture architectural aspects of proven solutions. In many cases, the chosen patterns have system-wide implications on non-functional requirements such as availability, performance, and resilience. Ensuring compliance with the selected patterns is of vital importa...
Preprint
Patterns describe proven solutions for recurring problems. Typically, patterns in a particular domain are interrelated and organized in pattern languages. As real-world problems often require patterns of multiple domains, different pattern languages have to be considered to address these problems. However, cross-domain knowledge about how patterns...
Preprint
Full-text available
Quantum computers are becoming real, and they have the inherent potential to significantly impact many application domains. We sketch the basics about programming quantum computers, showing that quantum programs are typically hybrid consisting of a mixture of classical parts and quantum parts. With the advent of quantum computers in the cloud, the...
Book
Service composition is a popular approach for building software applications from several individual services. Using imperative workflow technologies, service compositions can be specified as workflow models comprising activities that are implemented, e.g., by service calls or scripts. While scripts are typically included in the workflow model itse...
Article
Das aktuell vom Institut für Architektur von Anwendungssystemen (IAAS) der Universität Stuttgart und vom Data Center for the Humanities (DCH) der Universität zu Köln bearbeitete Projekt SustainLife â Erhalt lebender, digitaler Systeme für die Geisteswissenschaften befasst sich mit der Konservierung von Forschungssoftware im Bereich der Digital Huma...