The Design And Realization Of Real-time Messaging Middleware Rtps

ORB can be well capable to support the integration of distributed heterogeous application, while it lacks of the support to realtime messaging; MOM can do well in asynchronous decoupled communication within enterprise application,but it doesn't support inter-operation between different products from different vendors,which will set a barrier for future integration.Concerned about this and the demand of distributed realtime applications,such as satellite measure and control area,etc.,This thesis gives a special attention on communication models in distributed heterogeous environment,that is RPC, RMI, and Messaging .Based on the merits and flaws shown within,A realtime MOM based on ORB,named RTPS was introduced.Following the architecture description of RTPS middleware ,two critical implementation issues are carried out: the first,Object-Oriented multi-threaded architecture.To avoid negative effect brought by the block,and to improve the realtime responsive ability of the system ,we decouple the event processing from its transportation;the second,pooled memory allocationJn order to decrease the time-and-space overhead due to dynamic memory allocation,thus to improve the dynamic performance of the realtime publish-subscribe system and the predictability of runtime end-to-end QoS,we adopt the pooled allocation to change many dynamic system calls into one static system call and several user interface calls in fixed time. Their application environment,advantage and restrict are also discussed.This thesis has made three major contributions: 1. It demonstrates the feasibility of incorporating ORB with MOM, designs and implements RTPS,a ORB-based MOM, which focuses on decentralized real-time publish-subscribe, removes the bottleneck by simplifing the responsibility of one node, and adopts the collocated client/server to set up a peer-to-peer(P2P) communication style. 2. It points out the importance of asynchronous concurrent processing to dynamic responsive system, carries out a in-depth research on Object-Oriented multi-threaded architecture, designs and implements RTPS_Thread_Manager, studies the Active Object pattern in detail and implements its core,that is RTPSTask, as well as gives its varieties. 3. After giving all-sided analysis and evaluation on kinds of memory allocation pattern,it designs RTPS_Cached_Allocator ,a pooled memory allocator which can decrease the overhead resulted from the general dynamic heap allocation ,in order to improve the dynamic performance of a system and meet the demand of QoS predictability.A memory pool management framework, MPMF, is also shown.