Interface theories allow systems designers to reason about the composability and compatibility of concurrent system components. Such theories often extend both de Alfaro and Henzinger’s Interface Automata and Larsen’s Modal Transition Systems, which leads, however, to several issues that are undesirable in practice: an unintuitive treatment of specified unwanted behaviour, a binary compatibility concept that does not scale to multi-component assemblies, and compatibility guarantees that are insufficient for software product lines.
In this paper we show that communication mismatches are central to all these problems and, thus, the ability to represent such errors semantically is an important feature of an interface theory. Accordingly, we present the error-aware interface theory EMIA, where the above shortcomings are remedied by introducing explicit fatal error states. In addition, we prove via a Galois insertion that EMIA is a conservative generalisation of the established MIA (Modal Interface Automata) theory.
Orchestration languages are of paramount importance for building composite services in service-oriented architectures. Pattern-based analysis is a method that allows to determine the expressiveness of existing process languages and serves as a means of comparison between different languages. The aim of this study is the analysis and comparison of important languages for building Web Services-based orchestrations, as well as the improvement of the method of pattern-based analysis. The predominant orchestration language today is the Web Services Business Process Execution Language (WS-BPEL) 2.0. This language is a standard that has been implemented by several companies and projects, such as the OpenESB BPEL Service Engine. An additional language is Windows Workflow 4 that is shipped by Microsoft as part of the .NET framework. There are various aspects, represented by pattern catalogs, for which existing languages can be analyzed. This study suggests a methodology for ordering existing pattern catalogs according to their importance for a selected problem domain which is Business-to-Business Integration. It furthermore presents an extensive evaluation of the languages at hand and assesses the degree of support they provide for several of the most important pattern catalogs. These catalogs are the workflow control-flow patterns, the service interaction patterns, the change patterns and the time patterns.
By using the remote functions of a modern IT service management system infrastructure, it is possible to analyze huge amounts of logfile data from complex technical equipment. This enables a service provider to predict failures of connected equipment before they happen. The problem most providers face in this context is finding a needle in a haystack - the obtained amount of data turns out to be too large to be analyzed manually. This report describes a process to find suitable predictive patterns in log files for the detection of upcoming critical situations. The identification process may serve as a hands-on guide. It describes how to connect statistical means, data mining algorithms and expert domain knowledge in the domain of service management. The process was developed in a research project which is currently being carried out within the Siemens Healthcare service organization. The project deals with two main aspects: First, the identification of predictive patterns in existing service data and second, the architecture of an autonomous agent which is able to correlate such patterns. This paper summarizes the results of the first project challenge. The identification process was tested successfully in a proof of concept for several Siemens Healthcare products.
The WS-Agreement Standard as defined in the current proposal does not accommodate negotiation between service provider and requesters to yield an agreement. It is limited to simple offers and acceptances. However, negotiations between service providers and service consumers beyond the basic mechanism are required and are also part of the charter of the GRAAP working group. There are many mechanisms for negotiating agreements between parties for different purposes, having different sets of participants, different economic properties, different interactions patterns, and different information requirements to enter the interaction. Given the generality of the WS-Agreement scope, supporting a single negotiation mechanism would not satisfy the requirements of different application scenarios. Hence, the objective of this thesis is to devise a proposal to extend the WS-Agreement specification to facilitate the integration of arbitrary negotiation protocols into the WS-Agreement interaction. This includes facilities to enable a party to advertise the negotiation protocol it supports, the role that it can take in this protocol, expectations on other roles in the negotiation, and other meta-information that is necessary to start an interaction. This thesis analyzes the scope of negotiation protocols relevant for service level agreement establishment, derives a data structure for negotiation protocol meta-data, a protocol to exchange meta-data and initiate a negotiation protocol, and obtaining the result of the negotiation, the agreement. The new functionality extends the current WS-Agreement specification seamlessly. The thesis demonstrates the viability of the approach using scenarios of specific negotiation mechanisms.
Ever fiercer competition has forced enterprises not only to optimize their own operations but also to cooperate with their suppliers and customers along their supply chains. Thus, competition today usually takes place between supply chains and not between individual enterprises. Business-To-Business integration (B2Bi) is a major task of supply chain management (SCM), and although it already has been researched for years, B2Bi is still an area of active research with a plethora of research questions and according approaches. Hence, management of B2Bi projects necessitates the identification of relevant requirements which is a far from trivial task. This paper identifies a core set of B2Bi challenges and deduces a comprehensive set of B2Bi requirements that are particularly useful for tackling the challenges identified. The derivation of B2Bi requirements follows an inductive approach that is based on the analysis of integration standards, reference architectures and related literature. In order to operationalize the B2Bi requirements for further analysis and concrete B2Bi projects, the requirements are classified according to the abstraction layers of a B2Bi schema. Thus, this report not only offers a requirements check list for B2Bi projects but also helps in deciding when to address which requirements during the course of a B2Bi project.
Recently, service orientation has strongly influenced the way enterprise applications are built. Service ecosystems, which provide means to trade services between companies like goods, are an evaluation of service orientation. To allow service ordering, discovering, selection, and consumption, a common way to describe services is a necessity. This paper discusses existing approaches to describe certain service aspects. Finally, a Service Description Framework for service ecosystems is proposed and exemplified.
Since their invention as lightweight integration technology about a decade ago, Web Services have matured significantly. Today, major middleware solution vendors as well as industry communities like RosettaNet are propagating Web services even for exchanging business-critical data and implementing inter-organizational business processes. Core enablers for using Web services in this domain are stateful interactions using the Web Services Business Process Execution Language (WS-BPEL) as well as advanced communication features like security and reliability using the WS-Security and WS-ReliableMessaging standard specifications. However, advanced communication features come at the price of complexity which challenges interoperability across different Web services stack implementations. Interoperability, in turn, is a predominant requirement for an integration technology such as Web services, in particular if inter-organizational business processes are supposed to be implemented on top of that technology. This paper approaches the problem of testing the interoperability of the so-called WS-* standards, advanced Web services communication features that are typically defined as SOAP extensions and configured using WS-Policy. Being essential to business process integration, WS-Security and WS-ReliableMessaging are selected as representatives of this group and the two major Java-based Web services stack implementations Metro and Axis2 are tested for interoperability. We operationalize the notion of interoperability for testing WS-* standards, suppose an approach for deriving test cases from WS-* specifications as well as a method for performing the test cases, and we provide a comprehensive interoperability review of the two selected Web services stack implementations.
Business Process Management Systems (BPMS) aim to support the Business Process Management paradigm and to ease legacy application integration. Often, they rely on Service-oriented Architecture (SoA). However, do such systems really meet real-world requirements? This paper introduces and discusses a set of criteria which are important for BPMS and applies these criteria in comparing tools from three important vendors, namely IDS Scheer, Oracle and Intalio based on a case study.
More than five years have passed since the final release of the long-desired OASIS standard of a process language for web service orchestration, the Web Services Business Process Execution Language (BPEL). The aim of this standard is to establish a universally accepted orchestration language that forms a core part of current service-oriented architectures and, because of standardisation, avoids vendor lock-in. High expectations, in academia and practice alike, have been set on it. By now, several fully conformant and highly scalable engines should have arrived in the market. The perception of many however, is that standard conformance in current engines is far from given. It is our aim to shed light on this situation. In this study, we present the tool betsy, a BPEL Engine Test System that allows for a fully-automatic assessment of the standard conformance of a given BPEL engine. We use it to examine the five most important open source BPEL engines available today. Betsy comes with a large set of engineindependent conformance test cases for assessing BPEL standard conformance. This enables us to give a view of the state of the art in BPEL support.
Correct and standard compliant serializations of BPMN process models are crucial for model exchange between tools, automatic application of academic verification approaches and executability on BPMN engines. The official standard document does not provide an extensive set of all constraints regarding the correctness of model serializations. This technical reports fills this gap by presenting a categorized list of generic, technology independent constraints stated by the standard. Furthermore it is analyzed which rules are already covered when the standardized XSD-based serialization format is used.