Detecting emergent behavior in autonomous distributed systems with many components of the same type

In design of distributed systems with specification languages such as message sequence charts (MSC), communication between different component (agent) types or instances of them are defined. There are a number of methods to verify the design using scenarios of inter-component communication. Those methods usually ignore the intra-component communication, i.e. communication between components of the same type. However in large scale systems, such as e-commerce systems, there are several components of one type that may communicate with each other and this may violate some regulatory policies defined in the design. On the other hand, there are declarative policies in system design that need to be integrated in the implemented system. In this paper a method that takes a topology of the system and regulatory policies as its inputs and detects the components having emergent behavior at its output is proposed. This method is defined to reveal the components that may violate the policies in the design phase by defining message types and extracting a version of MSCs called modified MSCs (MMSCs). Then by clustering and analyzing the send messages in the communications of different components the violating components are detected. By applying this method, all instances of components can be examined for policy violation in the implemented system. The method is explained along with a case study of a realistic online auction system and it is shown how this method can detect the components with emergent behaviors.