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

Modeling and verification of web service composition based interorganizational workflows

Interorganisationale Workflows sind Arbeitsabläufe, welche die Grenzen einer Organisation verlassen und einen Rahmen für Kooperationen der verschiedenen autonomen Organisationen zur Verfügung stellen. Ein wichtiger Punkt für den Entwurf solcher Workflows ist die Balance zwischen Offenheit und Abgrenzung, wobei erstere für Kooperationen und letztere die für den Schutz von Know-how benötigt wird. Workflow Sichten stellen ein effizientes Werkzeug für diesen Zweck zur Verfügung. Durch Offenlegung von bestimmten Teilen eines Prozesses, können Organisationen sowohl kooperieren als auch das Know-how schützen. Diese Dissertation präsentiert nun eine Methode für die korrekte Konstruktion von Workflow Sichten. Es wird angenommen, dass Organisationen Web Service orientierte Technologien zur Modellierung und Implementierung von interorganisationalen Workflows verwenden. Die Anwendung von Web Services bietet Organisationen viele Vorteile. Den eigentlichen Mehrwert von Web Services stellt aber die Kompositionsfähigkeit dar. Verfügbare Web Services können dadurch von anderen Choreographien und Orchestrationen (wieder-)verwendet werden. Die Notwendigkeit der Implementierung von Systemen von Null weg kann minimiert werden. Die zentralen Anforderungen sind einerseits eine Architektur mit adäquatem Potential, andererseits die Verifikation der Korrektheit. Diese Dissertation präsentiert nun eine Architektur zur Modellierung von Web Service Composition basierten interorganisationalen Workflows, genannt föderierte Choreographien, die verglichen mit anderen Architekturen verschiedene Vorteile anbieten. Darüber hinaus werden Algorithmen und Techniken zur Verifikation der strukturellen und temporalen Korrektheit vorgestellt. Strukturelle Korrektheit prüft, ob die Strukturen der beteiligten Prozesse zusammenpassen. Temporale Korrektheit überprüft, ob ein interorganisationaler Workflow, der aus mehreren Choreographien und Orchestrationen besteht hinsichtlich der lokalen und globalen Bedingungen fehlerfrei ist. Mit Hilfe dieser Techniken kann die strukturelle und temporale Konformität des Modells zur Designzeit überprüft werden. Falls das Modell nicht strukturell oder temporal konform ist, können nötige Änderungen durchgeführt werden, sodass die korrekte Ausführung zur Laufzeit garantiert werden kann. Die Überprüfung der Konformität zur Designzeit reduziert die Prozesskosten vor allem wegen den folgenden zwei Gründen: Erstens, die entdeckten Fehler zur Designzeit sind normalerweise billiger als jene, die zur Laufzeit entdeckt werden und zweitens, Fehlerbehandlungsmechanismen können verhindert werden, die wiederum Zusatzkosten verursachen. Zusätzlich zu der vorgestellten Architektur wird eine allgemeinere Architektur zusammen mit den passenden Konformitätsprüfungsalgorithmen präsentiert. Der Ansatz ist Platform- und sprachunabhängig und die Algorithmen sind verteilt.Interorganizational workflows are workflows that cross the boundaries of a single organization and provide a framework for cooperation of different autonomous organizations. An important issue when designing such workflows is the balance between the openness needed for cooperation and the privacy needed for protection of business know-how. Workflow views provide an efficient tool for this aim. By exposure of only selected parts of a process, organizations can both cooperate and protect their business logic. This dissertation presents a technique for a correct construction of workflow views. It is assumed that organizations and partners use web services and web service related technology to model and implement interorganizational workflows. Application of web services offers several advantages for organizations. The real surplus of web services is their capability of being composed to more complex systems. Available web services can be reused by other choreographies and orchestrations and the need for development of new systems from scratch can be minimized. The essential requirements are on the one hand an architecture with adequate capabilities and on the other hand, verification of correctness. This dissertation proposes an architecture for modeling web service composition based interorganizational workflows, called \emph{federated choreographies}, that provides several advantages compared to existing proposals. Moreover, algorithms and techniques for verification of structural and temporal correctness of interorganizational workflows are proposed. Structural conformance checks if the structures of the involved processes match. Temporal conformance checks if an interorganizational workflow composed of choreographies and orchestrations is temporally error-free with respect to local and global temporal constraints. The proposed algorithms can be applied for checking the structural and temporal conformance of the federated choreographies at design-time. If the model is not structurally or temporally conformant, necessary modifications can be done such that the correct execution of the flow at run-time can be guaranteed. The conformance checking at design time reduces the cost of process because of two reasons: first, errors detected at design time are normally cheaper than those detected at run time and second, exception handling mechanisms can be avoided which are, in turn, coupled with additional costs. In addition to the proposed architecture, a more general architecture together with the conformance checking algorithms and techniques for interorganizational workflows are presented. The presented approach is language and platform independent and algorithms work in a distributed manner

Interdependent Security and Compliance in Service Selection

Application development today is characterized by ever shorter release cycles and more frequent change requests. Hence development methods such as service composition are increasingly arousing interest as viable alternative approaches. While employing web services as building blocks rapidly reduces development times, it raises new challenges regarding security and compliance since their implementation remains a black box which usually cannot be controlled. Security in particular gets even more challenging since some applications require domainspecific security objectives such as location privacy. Another important aspect is that security objectives are in general no singletons but subject to interdependence. Hence this thesis addresses the question of how to consider interdependent security and compliance in service composition. Current approaches for service composition do neither consider interdependent security nor compliance. Selecting suiting services for a composition is a combinatorial problem which is known to be NP-hard. Often this problem is solved utilizing genetic algorithms in order to obtain near-optimal solutions in reasonable time. This is particularly the case if multiple objectives have to be optimized simultaneously such as price, runtime and data encryption strength. Security properties of compositions are usually verified using formal methods. However, none of the available methods supports interdependence effects or defining arbitrary security objectives. Similarly, no current approach ensures compliance of service compositions during service selection. Instead, compliance is verified afterwards which might necessitate repeating the selection process in case of a non-compliant solution. In this thesis, novel approaches for considering interdependent security and compliance in service composition are being presented and discussed. Since no formal methods exist covering interdependence effects for security, this aspect is covered in terms of a security assessment. An assessment method is developed which builds upon the notion of structural decomposition in order to assess the fulfillment of arbitrary security objectives in terms of a utility function. Interdependence effects are being modeled as dependencies between utility functions. In order to enable compliance-awareness, an approach is presented which checks compliance of compositions during service selection and marks non-compliant parts. This enables to repair the corresponding parts during the selection process by replacing the current services and hence avoids the necessity to repeat the selection process. It is demonstrated how to embed the presented approaches into a genetic algorithm in order to ease integration with existing approaches for service composition. The developed approaches are being compared to state-of-the-art genetic algorithms using simulations

Timed protocol analysis of interconnected mobile IoT devices

International audienceWith the emergence of the Internet of Things (IoT), application developers can rely on a variety of protocols and Application Programming Interfaces (APIs) to support data exchange between IoT devices. However, this may result in highly heterogeneous IoT interactions in terms of both functional and non-functional semantics. To map between heterogeneous functional semantics, middleware connectors can be utilized to interconnect IoT devices via bridging mechanisms. In this paper, we make use of the Data eXchange (DeX) connector model that enables interoperability among heterogeneous IoT devices. DeX interactions, including synchronous, asynchronous and streaming, rely on generic post and get primitives to represent IoT device behaviors with varying space/time coupling. Nevertheless, non-functional time semantics of IoT interactions such as data availability/validity, intermittent connectivity and application processing time, can severely affect response times and success rates of DeX interactions. We introduce timing parameters for time semantics to enhance the DeX API. The new DeX API enables the mapping of both functional and time semantics of DeX interactions. By precisely studying these timing parameters using timed automata models, we verify conditions for successful interactions with DeX connectors. Furthermore, we statistically analyze through simulations the effect of varying timing parameters to ensure higher probabilities of successful interactions. Simulation experiments are compared with experiments run on the DeX Mediators (DeXM) framework to evaluate the accuracy of the results. This work can provide application developers with precise design time information when setting these timing parameters in order to ensure accurate runtime behavior

Privacy-preserved security-conscious framework to enhance web service composition

The emergence of loosely coupled and platform-independent Service-Oriented Computing (SOC) has encouraged the development of large computing infrastructures like the Internet, thus enabling organizations to share information and offer valueadded services tailored to a wide range of user needs. Web Service Composition (WSC) has a pivotal role in realizing the vision of implementing just about any complex business processes. Although service composition assures cost-effective means of integrating applications over the Internet, it remains a significant challenge from various perspectives. Security and privacy are among the barriers preventing a more extensive application of WSC. First, users possess limited prior knowledge of security concepts. Second, WSC is hindered by having to identify the security required to protect critical user information. Therefore, the security available to users is usually not in accordance with their requirements. Moreover, the correlation between user input and orchestration architecture model is neglected in WSC with respect to selecting a high performance composition execution process. The proposed framework provides not only the opportunity to securely select services for use in the composition process but also handles service users’ privacy requirements. All possible user input states are modelled with respect to the extracted user privacy preferences and security requirements. The proposed approach supports the mathematical modelling of centralized and decentralized orchestration regarding service provider privacy and security policies. The output is then utilized to compare and screen the candidate composition routes and to select the most secure composition route based on user requests. The D-optimal design is employed to select the best subset of all possible experiments and optimize the security conscious of privacy-preserving service composition. A Choreography Index Table (CIT) is constructed for selecting a suitable orchestration model for each user input and to recommend the selected model to the choreographed level. Results are promising that indicate the proposed framework can enhance the choreographed level of the Web service composition process in making adequate decisions to respond to user requests in terms of higher security and privacy. Moreover, the results reflect a significant value compared to conventional WSC, and WSC optimality was increased by an average of 50% using the proposed CIT