Abstract. This paper describes the design and the prototype implementation of a middleware, called Java Signal Core Layer (JSCL), for coordinating distributed services. JSCL supports the coordination of distributed services by exploiting an event notification paradigm. The design and the implementation of JSCL has been inspired and driven by its formal specification given as a process calculus, the Signal Calculus (SC). At the experimental level JSCL has been exploited to implement Long Running Transactions (LRTs).

Abstract. We propose a novel approach to service choreography through a typed process calculus that features an event notification paradigm for coordinating distributed components (e.g., services). Basically, the type system expresses coordination policies for handling the events spawn in a network so that distributed components react to events when the type of their public interface is "compatible" with (the policies expressed by) the types of signals.Remarkably, the type system can naturally handle multi-party sessions, as shown in the formalisation of the OpenID protocol which requires multi-party sessions for handling user identities.

We address the problem of composing Web Services in long-running transactional business processes, where compensations must be dealt with appropriately. The framework presented in this paper is a Java API called Java Transactional Web Services (JTWS), which provides suitable primitives for wrapping and invoking Web Services as activities in long-running transactions. JTWS adheres to a process calculi formalisation of long-running transactions, called Sagas, which fixes unambiguously the implemented compensation policy. In particular, the primitives provided by JTWS are in one-to-one correspondence with the primitives of Sagas, and they are abstract enough to hide the complex details of their realization, thus favouring usability. Moreover, JTWS orchestrates business processes in a distributed way

a b s t r a c tAn important feature of the service-oriented approach is the ability to aggregate, through programmable coordination patterns, the activities involved in service interactions. Two different approaches can be adopted to tackle service coordination: orchestration and choreography. In this paper, we introduce a formal methodology to handle coordination among services from the perspective of a global observer, in the spirit of choreography models. In particular, we address the problem of verifying compliance and consistency between the design of service interactions and the choreography constraints.