Research And Implement On Publish/Subscribe Middleware For Web Applications

With the rapid development of the Internet,publish/subscribe(p/s)communication schema in distributed system gains wide attention thanks to its decoupling characteristics and low-latency data connectivity.Data Distribution Service(DDS)is a middleware protocol and API standard for data-centric connectivity in distributed system.The most of DDS products are deployed in the LAN(Local Area Network).DDS lacks the support for web applications in the Internet environment.For this situation,restful Web DDS Service model is proposed in this thesis,which is based on the Web-Enabled DDS specification published by OMG.A publish/subscribe middleware prototype system for web applications is implemented by the Web DDS Service.Through the system,the web publishers and web subscribers can use standard web protocols to participante as first-class citizens as publishers and subscribers of data in the DDS Global Data space.The main work lists of this thesis as below:1.The Web DDS Service Model based on the Web-Enabled DDS specification is proposed.The restful Web DDS Service is defined in this model.In this model,the Web DDS object model is defined,and the function of these objects are described.2.A publish/subscribe middleware prototype system is designed and implemented for web applications based on the Web DDS Service Model.The implementation of the prototype system can be divide into two modules,the web business logical processing module and the web publish/subscribe localization module.In the first module,the APIs are provided by the prototype system for users,and the data is exchanged between the service and users.Besides,the objects in the system are managed and the business logic operations are processed.In the second module,the operations of web publish/subscribe operations are localized to realize the intercommunication between web participants and local participants.3.Functional and performance testing of the publish/subscribe middleware prototype system for web applications are performed to verify the correctness and validity of the implementation of the Web DDS Service and the publish/subscribe middleware prototype system for web applications.The result of the tests show that the implementation of the publish/subscribe middleware prototype system for web applications can efficiently support the development and running for the publish/subscribe distributed system in the web environment.