Marie-Christine Fauvet

Towards patterns of web services composition

The growth of the Internet has unleashed a wave of innovations that are reshaping the way organisations interact with their partners and customers. In particular, the concept of electronically-accessible service (also known as e-service or Web service) has gained a considerable momentum as a paradigm for supporting both Business-to-Consumer (B2C) interaction and Business-to-Business (B2B) collaboration.

Towards an Approach forWeb services Substitution

This paper presents an approach whose objective is to support Web services substitution. Substitution means replacing a component with another component, as long as the replacing component produces the same output and satisfies the same requirements as the replaced component. Motives for substitution include Web services non-responsiveness to client requests and better arrangement with another, competitor Web service. To perform Web services substitution with less impact on the ongoing, and sometimes critical, business processes, the approach proposes deploying communities of Web services. A community promotes the dynamic binding of Web services through a common interface, known as open service connectivity. The open service connectivity directs requests to and responses from Web services regardless of how these latter are specified, implemented, and located

Overview of some patterns for architecting and managing composite web services

The composition of Web services has gained a considerable momentum as a paradigm for enabling Business-to-Business (B2B) Collaborations. Numerous technologies supporting this new paradigm are rapidly emerging, thereby creating a need for methodologies that bring these technologies together. The identification and documentation of relevant patterns, both at the analysis and design levels, is an important step in this direction.

Handling transactional properties in web service composition

The development of new services by composition of existing ones has gained considerable momentum as a means of integrating heterogeneous applications and realising business collaborations. Services that enter into compositions with other services may have transactional properties, especially those in the broad area of resource management (e.g. booking services). These transactional properties may be exploited in order to derive composite services which themselves exhibit certain transactional properties. This paper presents a model for composing services that expose transactional properties and more specifically, services that support tentative holds and/or atomic execution. The proposed model is based on a high-level service composition operator that produces composite services that satisfy specified atomicity constraints. The model supports the possibility of selecting the services that enter into a composition at runtime, depending on their ability to provide resource reservations at a given point in time and taking into account user preferences.

Peer-to-Peer Traced Execution of Composite Services

The connectivity generated by the Internet is opening unprecedented opportunities of automating business-to-business collaborations. As a result, organisations of all sizes are forming online alliances in order to deliver integrated value-added services. Unfortunately, due to a lack of tools and methodologies offering an adequate level of abstraction, the development of these integrated services is currently ad hoc and requires a considerable effort of low-level programming, especially when dealing with coordination, communication, and execution tracing issues. In this paper, we present a framework through which business services can be declaratively composed, and the resulting composite services can be executed in a fully traceable manner. The traces of a composite service executions are collected incrementally through peer-to-peer interactions between the involved providers. Once collected, these traces are stored as linked objects in distributed repositories, which are made available for auditing, customer feedback and quality assessment.

Fragment-based version management for repositories of business process models

As organizations reach higher levels of Business ProcessManagement maturity, they tend to accumulate large collections of processmodels. These repositories may contain thousands of activities and be managed by different stakeholders with varying skills and responsibilities. However, while being of great value, these repositories induce high management costs. Thus, it becomes essential to keep track of the various model versions as they may mutually overlap, supersede one another and evolve over time. We propose an innovative versioning model, and associated storage structure, specifically designed to maximize sharing across process models and process model versions, reduce conflicts in concurrent edits and automatically handle controlled change propagation. The focal point of this technique is to version single process model fragments, rather than entire process models. Indeed empirical evidence shows that real-life process model repositories have numerous duplicate fragments. Experiments on two industrial datasets confirm the usefulness of our technique.

Handling temporal grouping and pattern-matching queries in a temporal object model

This paper presents a language for expressing temporal pattern-matching queries, and a set of temporal grouping operators for structuring histories following calendar-based criteria. Pattern-matching queries are shown to be useful for reasoning about successive events in time while temporal grouping may be either used to aggregate data along the time dimension or to display histories. The combination of these capabilities allows to express complex queries involving succession in time and calendar-based conditions simultaneously. These operators are embedded into the TEMPOS temporal data model and their use is illustrated through examples taken from a geographical application. The proposal has been validated by a prototype on top of the O2 DBMS.

Collecting and Querying Distributed Traces of Composite Service Executions

The development of new Web services by composition of existing ones is becoming a widespread approach to realise business-to-business collaborations. The composite services obtained in this way are then eventually used in other compositions. Given the dynamic nature of the Web, this recursive composition of services rapidly leads to intricate dependencies between them. On the other hand, businesses need to track the executions of their composite services in order to ensure explainability in case of failure and to support decision making. This paper deals with the issue of tracing composite service executions over the Web. It describes a model and an XML representation of service execution traces, an approach for collecting and storing these traces in a distributed environment, and an approach to evaluate queries over distributed repositories of traces.

Diagnosing Incompatibilities in Web Service Interactions for Automatic Generation of Adapters

Interactions between two applications encapsulated into Web services consist in series of message exchanges that must conform to service interfaces. The study reported in this text aims at dealing with the issues that arise when interactions between two services (a client and a provider) fail because their interfaces are incompatible. This may happen because the provider has evolved and its interface has been modified. It may also happen because the client decided to change for another provider which addresses the same needs but offers a different interface. The contribution of the proposed approach is twofold. First, given two services, all incompatibilities that may exist between their interfaces are automatically detected and classified into patterns. Second, according to the patterns that have been recognized, an adapter is then automatically generated. This latter is intended to act as an intermediate between the client and the provider, therefore seamlessly reconciling interactions between them.

Using CEP technology to adapt messages exchanged by web services

Web service may be unable to interact with each other because of incompatibilities between their interfaces. In this paper, we present an event driven approach which aims at adapting messages exchanged during service interactions. The proposed framework relies on the Complex Event Processing (CEP) technology, which provides an environment for the development of applications that need to continuously process, analyse and respond to event streams. Our main contribution is a system that enables developers to design and implement CEP-based adapters. These latter are deployed in a CEP engine which is responsible for continuously receiving messages and processing them according to rules implemented by the adapters. Resulting transformed messages are thus forwarded to their original service recipient.