Johannes Schwalb

Bio: Johannes Schwalb is an academic researcher. The author has contributed to research in topics: Web service & ebXML. The author has an hindex of 3, co-authored 4 publications receiving 21 citations.

Has WS-I's Work Resulted in Ws-* Interoperability?

Abstract: Recently, the Web Services Interoperability Organization(WS-I) has announced to have completed its interoperability standards work. The latest deliverables include the so-called "Basic Security Profile" and the "Reliable SecureProfile". This gives rise to the question whether or not Web Services adopters can rely on interoperability of Web Services stacks, in particular in terms of security and reliability features. To answer this question, we thoroughly analyze two important Web Services stacks for interoperability of WS-Security and WS-Reliable Messaging features. Our analysis shows that security and reliability features are far from being implemented in an interoperable manner. Additionally, we reveal that some of those interoperability problems are not even covered by WS-I profiles and therefore conclude that WS-I's work has not yet resulted in Web Services interoperability.

QoS-Enabled Business-to-Business Integration Using ebBP to WS-BPEL Translations

Abstract: Business-To-Business Integration (B2Bi) is a key mechanism for enterprises to gain competitive advantage. However,developing B2Bi applications is far from trivial. Inter alia,agreement among integration partners about the business documents and the control flow of business document exchanges, applying suitable communication technologies for overcoming heterogeneous IT landscapes as well as ensuring a Quality of Service (QoS) level that is sufficient for B2Bi are major challenges.In this context, applying choreography languages like ebXML BPSS (ebBP) for agreement among integration partners, orchestration languages like WS-BPEL for specifying partner-specific behavior, and Web Services for communication promises seamless interactions among business partners. In this scenario, the conformance of orchestration models to choreography models and cost-effective development are of paramount importance.Consequently, top-down approaches that automatically translate choreography models into orchestration models have been proposed.By now, the realization of QoS attributes has not yet received the necessary attention that makes such approaches suitable for B2Bi. In this paper, we describe a proof-of-concept implementation of a translation of ebBP choreographies into WS-BPEL orchestrations that respects B2Bi relevant QoS attributes.

Interoperability and Functionality of WS-* Implementations

Abstract: Recently, the Web Services Interoperability Organization WS-I has announced to have completed its interoperability standards work. The latest deliverables include the so-called "Basic Security Profile" and the "Reliable Secure Profile." This gives rise to the question whether or not Web Services adopters can rely on interoperability and functionality of Web Services stacks, in particular in terms of security and reliability features. To answer this question, the authors thoroughly analyze two important Web Services stacks for interoperability of WS-Security and WS-ReliableMessaging features. Their analysis shows that security and reliability features are far from being implemented in an interoperable manner. Additionally, they reveal that some of those interoperability problems are not even covered by WS-I profiles and therefore conclude that WS-I's work has not yet resulted in Web Services interoperability. Finally, the authors investigate support for the so-called "Secure WS-ReliableMessaging Scenario" in order to find out whether WS-* adopters can at least rely on the availability of real-world functionality in homogeneous environments.

QoS-Enabled B2B Integration

Abstract: Business-To-Business Integration (B2Bi) is a key mechanism for enterprises to gain competitive advantage. However, developing B2Bi applications is far from trivial. Inter alia, agreement among integration partners about the business documents and the control flow of business document exchanges as well as applying suitable communication technologies for overcoming heterogeneous IT landscapes are major challenges. At the same time, choreography languages such as ebXML BPSS (ebBP), orchestration languages such as WS-BPEL and Web Services are promising to provide the foundations for seamless interactions among business partners. Automatically translating choreography agreements of integration partners into partner-specific orchestrations is an obvious idea for ensuring conformance of orchestration models to choreography models. Moreover, the application of such model-driven development methods facilitates productivity and cost-effectiveness whereas applying a service oriented architecture (SOA) based on WS-BPEL and Web Services leverages standardization and decoupling. By now, the realization of QoS attributes has not yet received the necessary attention that makes such approaches suitable for B2Bi. In this report, we describe a proof-of-concept implementation of the translation of ebBP choreographies into WS-BPEL orchestrations that respects B2Bi-relevant QoS attributes.

Translating shared state based ebXML BPSS models to WS-BPEL

Abstract: In the Business-to-Business integration (B2Bi) domain, ebXML BPSS (ebBP) as dedicated B2Bi choreography standard is well-suited as means for agreement upon the overall message exchanges among integration partners while executable WS-BPEL orchestrations derived from ebBP choreographies are well-suited for governing the local message flow of each individual participant. In order to enable complex integration scenarios, this paper introduces the concept of partner-shared states into ebBP. We describe the modelling of shared states in ebBP and specify the formalisation and operational semantics of shared state-based ebBP models. A prototypic translation tool provides the realisation of the operational semantics as WS-BPEL orchestrations.

On the Portability of Applications in Platform as a Service

Abstract: In recent years, the cloud hype has led to a multitude of different providers and offerings across the entire cloud market, from Infrastructure as a Service (IaaS) to Platform as a Service (PaaS) to Software as a Service (SaaS). Despite the high popularity, there are still a number of problems and deficiencies. In particular with PaaS, the advertised portability between different clouds is hampered by a heterogeneous, difficult to compare provider landscape, technological differences between providers, and the lack of common standards. Therefore, the selection of a suitable provider and a potential change between different providers may involve substantial (migration) costs. Thus, the thesis deals with the analysis and improvement of application portability in PaaS environments. In the course of this, obstacles over the typical life cycle of an application – from the selection of a suitable cloud provider, through the deployment of the application, to the operation of the application – are considered. As foundation for further investigations, an improved delimitation and conceptualization of PaaS through a categorization, the definition of a reference model, and the establishment of a knowledge database is presented. As it turns out, in particular the heterogeneous provider landscape in this area is an obstacle for the assessment and feasibility of application portability. To solve this problem, the thesis presents a decision support system for the selection and comparison of suitable cloud platforms. Based on the PaaS model, a heuristic is proposed which can identify potential partners by matching the technological software ecosystem of the providers with the requirements of an application or a user. With the help of this system, it is possible for a user to identify offerings that enable application portability. To validate the approach, a case study with a real-world application is conducted that is migrated to different cloud platforms. In this context, we also develop a suitable assessment framework for measuring migration efforts, which allows making the differences between compatible providers quantifiable. The application management interface of the providers is identified as a central effort factor of the migration. Despite the semantically identical use cases, different interfaces are used by the providers for the management of the application’s life cycle. Finally, to reduce the effort in this area, the thesis presents a unified interface for application deployment and management. In summary, the work provides evidence of application portability problems in PaaS environments and presents a framework for early detection and avoidance. In addition, the results of the work contribute to a reduction of lock-in effects by proposing a suitable standard for management interfaces.

The CHORCH B2Bi Approach: Performing ebBP Choreographies as Distributed BPEL Orchestrations

Abstract: Applying choreography and orchestration technology has become a popular method of attacking Business-2-Business integration (B2Bi) challenges like agreement and communication among integration partners, compatibility of interacting processes and distributed computing. ebXML BPSS (ebBP) as dedicated B2Bi choreography standard and WS-BPEL as number one Web service orchestration language are particularly promising technologies. While ebBP can be used as means for agreement and communication among integration partners WS-BPEL and Web services can be used to solve distributed computing issues. The CHORCH approach applies model driven development to the ebBP-BPEL tool chain in order to further foster conformance of WS-BPEL orchestrations to ebBP choreographies, compatibility of interacting WS-BPEL processes and efficient software development cycles. This paper introduces 10 requirements for applying choreography and orchestration technology to B2Bi and shows how these are reflected in the CHORCH approach by applying three different types of ebBP modeling flavors.

Model Driven Conformance Testing for Standardized Services

Abstract: Software applications that are provided through services following the Software as a service (SaaS) paradigm generally need to be compliant to some standards. In order to select the software application that provides the most conformant service interface, we develop a formal framework that tests the compliance and reports quantitative results that help experts to take the right decision. Unlike existing work that focuses on a single dimension when checking the compliance of a software application with the corresponding standard (for example the functional dimension exclusively, or the syntactic dimension exclusively), in this work we consider multiple dimensions at the same time. This provides more comprehensive results. We implemented a prototype and we tested our framework on a case study regarding the selection of software applications for our collaborative platform.

Describing and Selecting Collections of Georeferenced Media Items in Peer-to-Peer Information Retrieval Systems

Abstract: The ever-increasing amount of media items on the World Wide Web and on private devices leads to a strong need for adequate indexing and search techniques. Trends such as personal media archives, social networks, mobile devices with huge storage space, and networks with high bandwidth capacities make distributed solutions and in particular Peer-to-Peer (P2P) Information Retrieval (IR) systems attractive. On the other hand, when designing effective media search applications, various search criteria have to be addressed. Hereby, geospatial information is frequently used as well as other criteria, such as text, audio or visual media content, and date and time information. In this chapter, the authors outline how collections of georeferenced media items can be indexed and searched in P2P IR systems. They discuss different types of P2P IR systems and focus in detail on an approach based on collection description and selection techniques. This approach tries to adequately describe and select collections of georeferenced media items. Finally, the authors discuss its broad applicability in various application fields.