Elastic Business Process Management: State of the Art and Open Challenges for BPM in the Cloud

With the advent of cloud computing, organizations are nowadays able to react rapidly to changing demands for computational resources. Not only individual applications can be hosted on virtual cloud infrastructures, but also complete business processes. This allows the realization of so-called elastic processes, i.e., processes which are carried out using elastic cloud resources. Despite the manifold benefits of elastic processes, there is still a lack of solutions supporting them. In this paper, we identify the state of the art of elastic Business Process Management with a focus on infrastructural challenges. We conceptualize an architecture for an elastic Business Process Management System and discuss existing work on scheduling, resource allocation, monitoring, decentralized coordination, and state management for elastic processes. Furthermore, we present two representative elastic Business Process Management Systems which are intended to counter these challenges. Based on our findings, we identify open issues and outline possible research directions for the realization of elastic processes and elastic Business Process Management.Comment: Please cite as: S. Schulte, C. Janiesch, S. Venugopal, I. Weber, and P. Hoenisch (2015). Elastic Business Process Management: State of the Art and Open Challenges for BPM in the Cloud. Future Generation Computer Systems, Volume NN, Number N, NN-NN., http://dx.doi.org/10.1016/j.future.2014.09.00

LightSwap: An Atomic Swap Does Not Require Timeouts At Both Blockchains

Security and privacy issues with centralized exchange services have motivated the design of atomic swap protocols for decentralized trading across currencies. These protocols follow a standard blueprint similar to the 2-phase commit in databases: (i) both users first lock their coins under a certain (cryptographic) condition and a timeout; (ii-a) the coins are swapped if the condition is fulfilled; or (ii-b) coins are released after the timeout. The quest for these protocols is to minimize the requirements from the scripting language supported by the swapped coins, thereby supporting a larger range of cryptocurrencies. The recently proposed universal atomic swap protocol [IEEE S&P’22] demonstrates how to swap coins whose scripting language only supports the verification of a digital signature on a transaction. However, the timeout functionality is cryptographically simulated with verifiable timelock puzzles, a computationally expensive primitive that hinders its use in battery-constrained devices such as mobile phones. In this state of affairs, we question whether the 2-phase commit paradigm is necessary for atomic swaps in the first place. In other words, is it possible to design a secure atomic swap protocol where the timeout is not used by (at least one of the two) users? In this work, we present LightSwap, the first secure atomic swap protocol that does not require the timeout functionality (not even in the form of a cryptographic puzzle) by one of the two users. LightSwap is thus better suited for scenarios where a user, running an instance of LightSwap on her mobile phone, wants to exchange coins with an online exchange service running an instance of LightSwap on a computer. We show how LightSwap can be used to swap Bitcoin and Monero, an interesting use case since Monero does not provide any scripting functionality support other than linkable ring signature verification

Fifty Shades of Grey in SOA Testing

Abstract-Testing is undisputedly a fundamental verification principle in the software landscape. Today's products require us to effectively handle and test huge, complex systems and in this context to tackle challenging traits like heterogeneity, distribution and controllability to name just a few. The advent of ServiceOriented Architectures with their inherent technological features like dynamics and heterogeneity exacerbated faced challenges, requiring us to evolve our technology. The traditional view of white or black box testing, for example, does not accommodate the multitude of shades of grey one should be able to exploit effectively for system-wide tests. Today, while there are a multitude of approaches for testing single services, there is still few work on methodological system tests for SOAs. In this paper we propose a corresponding workflow for tackling SOA testing and diagnosis, discuss SOA test case generation in more detail, and report preliminary research in that direction

ViePEP - Vienna Platform for Elastic Processes

Zsfassung in dt. SrpacheIn dieser Arbeit stellen wir ein Business Process Management System (BPMS) für die Cloud vor. Dieses BPMS kann mehere hundert Geschäftsprozesse (BPs) simultan bearbeiten und aus- führen. Diese BPs werden während der Ausührung beobachtet um auf etwaige Dienstgüterver- inbarungen verstöße frühzeitig zu reagieren, mehr Resourcen anzuforder wenn nötig, oder nicht mehr gebrauchte Resourcen freizugeben.Elastische Prozesse (EPs) sind ein neuartiges Konzept aus dem Bereich von Cloud Com- puting bei dem die Vielartigkeit der Elastizität der Cloud zum Einsatz kommt. EPs zeichnen sich durch 3 Eigenschaften aus: Kosten Elastizität, Resourcen Elastizität und Qualiät Elastizi- tät. Diese Elastizitäten spielen heutzutage ebenfalls bei BPMSs in der Cloud eine große Rolle.Ein BP besteht aus mehreren einzelnen Prozessen die alle unterschiedliche Anforderungen an Resourcen haben, andere Qualiätskriterien gelten und somit auch unterschiedlich hohe Kosten anfallen. Die Anzahl der gleichzeitig auszuführenden BPs kann über die Zeit enorm variieren, und dadurch auch die Anzahl der benötigten Resourcen. Daher kann es notwendig sein, dass während der Laufzeit zusätliche Resourcen angefordert, oder nicht mehr benötigte Resourcen wieder freigegeben werden.Wir entwickelten daher ViePEP - the Vienna Platform for Elastic Processes. ViePEP ist gleichzeitig ein BPMS welches in der Lage ist, mehrere hundert BPs gleichzeitig ausführen zu können, ihre Abarbeitungen zu beobachten und etwaiigen Dienstgüterverinbarungen verstößen frühzeitig entgegen zu steueren. Weiters ist es in der Lage BPs nach ihrer Priorität zu sortieren, so dass ausgemachte Vereinbarungen über die Dienstgüter der einzelnen Services nicht gebrochen werden. Weiters ist ViePEP in der Lage gegen etwaige Resourcenknappheit frühzeitig entgegen zu wirken. Mit Hilfe eines Prediction Models, kann ViePEP die benötigten Resourcen für die nahe Zukunft vorhersagen um zusätlich benötigte Resourcen rechtzeitig anzufordern oder unnö- tige freizugeben.Mittels ausführlichen Experimenten mit unterschiedlichen Einstellungen haben wir gezeigt, dass ViePEP in der Lage ist, automatisiert BPs auszuführen, auf alle Dienstgüterve- rinbarungen zu achten und automatisch neue Resourcen anzufordern oder freizugeben.Within this thesis, we propose a novel Business Process Management System for the Cloud. It is able to process several hundred workflows simultaneously while monitoring their executions in order to counteract against potential Service Level Agreement violations through scheduling the queued workflows and acquiring additional computing resources when needed or releasing unneeded ones.Elastic Processes are a novel paradigm from the field of Cloud computing. It combines the various facets of elasticity that captures process dynamics in the Cloud. Elastic Processes are described in three ways: cost elasticity, resource elasticity and quality elasticity. Nowadays, these elasticities are also relevant for workflows in the Cloud. A workflow consists out of several individual processes, each requires a different amount of resources, follows different Quality-of- Service attributes and produces a different amount of costs. Since in today's workflows resource intensive tasks get more and more common, and the amount of workflows executed in parallel varies over time, the amount of needed resources will also diversify enormous. That is way it is necessary to acquire additional computing resources during the system's runtime, or release some whenever they are not needed anymore.Therefore, we developed ViePEP - the Vienna Platform for Elastic Processes. ViePEP is on the one hand a Business Process Management System for the Cloud, capable to manage and process the execution of several hundred workflows simultaneously. It further monitors their executions in order to identify potential Service Level Agreement violations in time. And on the other hand, ViePEP is able to counteract against the lack of needed or the excess of used computing resources. Using a prediction model, ViePEP is not just able to counteract in-time but also predict the future need of resources for the near future in order to acquire additional resources punctual or release unneeded resources. By evaluating ViePEP with different config- ured experiments we have shown, that ViePEP is able to automatically process workflows, while taking care of Service Level Agreements through scheduling their executions and acquiring or releasing computing resources.9