I'm looking for example for dynamic routing with .net 4 wcf service. please help me.
Here are some resources that should help you get started:
Bridging and Error Handling routing sample
Advanced Filters routing sample
Advanced error handling routing sample
Routing topic on MSDN -- full coverage of services, contracts, filters, and scenarios
Routing Rules! Blog -- the entire blog is about the routing service and the different scenarios it enables. Take a read through all the blog posts for sure.