中文摘要：

针对协同系统的特点以及其对可靠性、实时性和性能等方面的要求，提出了一种可扩展的动态容错模型xDFT（Extensible Dynamic Fault Tolerance Model，xDFT）．本容错模型将容错支持结构和容错机制结合在一起：在本模型中首先定义了一种可扩展的、动态容错支撑结构；基于此，提出了一种容错机制．xDFT模型能够根据系统负载状况设定服务节点的负载阈值，改变服务冗余度，不仅提高了服务效率，而且以一种简单有效的方式实现了负载平衡．

英文摘要：

According to the requirement of high-availability, real-tlme and high performance in cooperative system, an extensthie dynamic fault tolerance model （xDFT） is proposed in the paper. The model combines fault tolerance supporting architecture and fault tolerance method： Firstly, an extensible dynamic fault tolerance supporting architecture is defined; then a fault tolerance mechanism, based on the fault tolerance supporting architecture is proposed, xDFT model can dynamically set load quality of server node with variability of system load to change server redundancy. It not only improves the service efficiency, but also implements load balancing in a more efficient and simply way.