Dynamic Topology Strategy Towards Publish/Subscribe Paradigm

Publish/Subscribe and its variations have been used in many large-scale distributedapplications and systems due to its scalability and loosely coupled nature, and it‘s getting alot of attention from more and more research institutions and commercial organizations.At the same time, how to keep the robust of topology which constructed with brokers andimprove the efficiency of message dissemination in a pub/sub system has become a hottopic in distributed research area. To deal with the disadvantages of supporting only onekind of typology, a brand new dynamic topology strategy is proposed which allowstopology to switch between difficult patterns dynamically to make tradeoffs betweensystem performance and robust.Pub/sub system makes transform on topology mainly based on environment-topologyfit which is obtained by detecting the brokers in topology continuously and processing andanalyzing test data. Detect module sends detecting designed signals to topologyperiodically which makes brokers to test connections between themselves and theirneighbors and store test data. Controller calls data processor and data analyzer to processand analyze stored test data using topology strategy decision technique and topologytransform technique, and make dynamic adjustments and transform on topology. At thesame time, design two dynamic topologies algorithms for the strategy which are TopologyGeneration Algorithm and Topology Transform Algorithm to mange the topology ininitialization phase and system run-time phase. In summary, pub/sub dynamic topologystrategy takes advantages of tree-based topology and cyclic topology, the system using thisstrategy to achieve the goal of reducing system cost and the delay of delivery andmaintaining the robust of system as well.Since pub/sub systems adopt dynamic topology strategy mentioned above, the testdata shows systems are able to run in various environments efficiently and stably. At thesame time, the average number of edges in the topology reduces by12%and subscriptionnotification delivery time improves by20%.