Technologies for E-Services

Whether two web services are compatible depends not only on static properties like the correct typing of their message parameters, but also on their dynamic behaviour. Providing a simple description of the service behaviour based on process-algebraic or automata-based formalisms can help detecting many subtle incompatibilities in their interaction. Moreover, this compatibility checking can to a large extent be automated if we define the notion of compatibility in a sufficiently formal way. Based on a simple behavioural representation, we survey, propose and compare a number of formal definitions of the compatibility notion, and we illustrate them on simple examples.

Web services are computational entities distributed on the web whose goal is to cooperate in order to work out simple or complex tasks. In this paper, we advocate the use of process algebra as an abstract and formal description formalism to tackle several issues raised in the context of web services. Abstract processes are helpful to describe services at different levels of expressiveness depending on the goal at hand and to compose them in order to build more complicated services. A great interest of using process algebra is that formal reasoning is made possible at any time and for many purposes (e.g. composition correctness) thanks to the existence of state-of-the-art tools. Abstract descriptions may also be used as a first step to develop certified web services following a well-defined method. We discuss all these ideas in this paper, reinforcing them with simple examples.

By its very nature, financial information, like the money that it represents, changes hands. Each player in the financial industry, each bank, stock exchange, government agency, or insurance company operates its own financial information system or systems. Therefore the interoperation of financial information systems is the cornerstone of the financial services they support. E-services frameworks, such as web services, are an unprecedented opportunity for the flexible interoperation of financial systems. Naturally the critical economic role and the complexity of financial information led to the development of various standards. Yet standards alone are not the panacea: different groups of players use different standards or different interpretations of the same standard. We believe that the solution lies in the convergence of flexible E-services such as web-services and semantically rich meta-data as promised by the semantic Web; then a mediation architecture can be used for the documentation, identification, and resolution of semantic conflicts arising from the interoperation of heterogeneous financial services. In this paper we illustrate the nature of the problem in the Electronic Bill Presentment and Payment (EBPP) industry and the viability of the solution we propose. We describe and analyze the integration of services using four different formats: the IFX, OFX and SWIFT standards, and an example proprietary format. To accomplish this integration we use the COntext INterchange (COIN) framework. The COIN architecture leverages a model of sources and receivers’ contexts in reference to a rich domain model or ontology for the description and resolution of semantic heterogeneity.