I am wondering that I can do same thing from both .net remoting and WCF, then why WCF is more preferred over .Net remoting. Where can I choose (or in which situation) .Net remoting or WCF?
Answer
.NET Remoting applications can use the HTTP, TCP, and SMTP protocols whereas WCF can use named pipes and MSMQ as well along with all these protocols.
You may find the best answer here: From .NET Remoting to the Windows Communication Foundation
Conclusion
As you have seen, a migration from .NET Remoting to WCF is not a task you have to be afraid of. For most applications, a simple three-step process can bring your application to the new platform. In most cases, you will only have to mark your interface contracts with [ServiceContract] and [OperationContract], your data structures with [DataContract] and [DataMember] and maybe change some parts of your activation model to be based on sessions instead of client-activated objects.
If you decide that you want to take advantage of the features of the Windows Communication Foundation, the complete migration from .NET Remoting to WCF should therefore be a rather easy task for the majority of applications.
You may also find the performance difference between the two in A Performance Comparison of Windows Communication Foundation (WCF) with Existing Distributed Communication Technologies
When migrating distributed applications written with ASP.NET Web Services, WSE, .NET Enterprise Services and .NET Remoting to WCF, the performance is at least comparable to the other existing Microsoft distributed communication technologies. In most cases, the performance is significantly better for WCF over the other existing technologies. Another important characteristic of WCF is that the throughput performance is inherently scalable from a uni processor to quad processor.
To summarize the results, WCF is 25%—50% faster than ASP.NET Web Services, and approximately 25% faster than .NET Remoting. Comparison with .NET Enterprise Service is load dependant, as in one case WCF is nearly 100% faster but in another scenario it is nearly 25% slower. For WSE 2.0/3.0 implementations, migrating them to WCF will obviously provide the most significant performance gains of almost 4x.