What is the difference between an asp.net web method and a wcf service?

ASP.NET Web services was developed for building applications that send and receive messages by using the Simple Object Access Protocol (SOAP) over HTTP.

WCF is for enabling .NET Framework applications to exchange messages with other software entities. SOAP is used by default, but the messages can be in any format, and conveyed by using any transport protocol.

You can view ASP.NET web services as a subset of WCF services.

Here is a link comparing the two frameworks.

it is quite easy to know the differences.

ASP.NET Web Method is called ASMX [because of the file extension] (check 4GuysFromRolla about this, they have a good tutorial)

That technology makes you expose functions as a Web Service so you can connect it from everywhere and use it. But... you can't protect the data between server and client, you can send big files clear and know what happend, etc...

[Note] you can protect the access to the web service using certificates, but it is complicated but normally, in ASMX we use username / passsword.

in WCF, you are in the different world about Web Services,and this s the best technology in .NET to expose Services (can you see the difference... Services! not Web Services), WCF does not need IIS to run, it can run as a System Service on the server, using a console ambient (like command line), etc, so we say that WCF is a Service not Web Service. Remember ASMX need IIS to run.

with WCF you can use SSL to encrypt the communication (to do that in ASMX you need to use WSE - Web Services Enhancements), you can send big files and securely (to do that in ASMX you need to use MTOM - Message Transmission Optimization Mechanism).

you can set the transmission preferences just changing one line of code, the security is much higher, etc, etc :)

hope you get a better general overview with this, but there is much more.

bottom line: to expose Web Services that you do not need to protect, you can use ASMX, no problem at all, but if you need to protect the communication somehow, do it in WCF!

link: you can read here some performance comparative between the 2 services

They are two different frameworks for writing services. WCF is generally more flexible and provides configurable options for what protocols are used, how the service is hosted and a variety of security options. ASMX offers SOAP based services. Generally WCF is also more performant. In general ASMX is easier to use and generally has less of a learning curve.

Here is a MSDN forum discussion on the topic.Here are the getting started pages for ASMX and WCF.