1. Polly

Polly is a .NET 3.5 / 4.0 / 4.5 / PCL library that allows developers to express transient exception and fault handling policies such as Retry, Retry Forever, Wait and Retry, or Circuit Breaker in a fluent manner. http://www.thepollyproject.org

简单的应用示例可以看这里：http://www.cnblogs.com/hj4444/p/4746616.html

有用的.NET库