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Abstract-Service Oriented Architecture (SOA) is a computer model that aims at building new software by assembling independent and loosely coupled services. Traditional web service orchestration is a mechanism for combining and coordinating different web services based on a predefined pattern. However the orchestration requirements may evolve due to business needs. In business context, the declarative approach has emerged to provide flexibility by modeling what must be done but not how it must be executed through business rules. When working with such a model, the results produced depend on the users' preferences. It is therefore fundamental that orchestration mechanisms provide simple yet efficient ways to dynamically make service composition. This paper proposes a web service orchestrator for declarative processes that makes service composition at runtime. The resulting business process obey all the business rules. The composition is done as the user chooses the service to run, providing an application-aligned infrastructure that can be scaled based on the needs of each business process, since it is described using declarative strategy.
Keywords: Service Oriented Architecture, runtime orchestration, flexible process, dynamic service composition.
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1. Introduction
Service Oriented Architecture (SOA) is a software architecture that focuses on delivering functionalities through services that can be reused across an enterprise. However these services are independent, they are defined in sequences to fulfill business processes. Services operate without any context from other processes within the organization.
Not only can SOA deliver on its promises of reusability and ability (usefulness), but it can also reduce the overall cost of ownership through the standards-based approach (ease of use) [1]. Moreover, SOA provides a complete integration between data and application.
Web services are an established technology for implementing SOA. They can be composed to create a higher level services or applications. Through service composition a complex service can be created by aggregating component services available. Conventionally, the web service composition specifies what services need to be invoked, in what order, and how to handle exceptional conditions [2]. Standard interfaces (such as WSDL), protocols (such as SOAP) for describing and invoking web services, and the loose-coupling of these services are important characteristics that lead to more interoperable distributed systems [3].
The SOA orchestration mechanism uses a central process to control...