Message passing and event-driven communication models for tree-structured applications

In this paper, we propose different techniques for message passing and event-driven communication among hierarchically organized objects. Proposed techniques are suitable for dynamic tree-structured applications, where application entities are organized in a tree and added to it in run time. Examples of such applications are modeling and simulation tools where application objects often follow parent-child relationship. We analyze the complexity of the proposed communication models from the perspective of number of hops messages needed to reach their final destinations and memory required to store routing information. The complexity of tree-based message passing is analyzed against the model based on a hash map, while four different techniques for event-driven communication are compared mutually to each other. Since the performance of a particular technique depends on the tree dynamics (how often objects are added to and removed from the tree) and scope of communication (localized among objects that belong to the same subtree or global across the tree), we derived conclusions about their applicability for different classes of applications.