Hi,

I think I know the diffrence between an .ashx file and an .axd registred in web.config, but I wonder if there is a particular reason to use the one or the other in a project, and why ?

Does anyone has a clear explanation on this ?
Are there best-practices to choose whether to use ashx or axd ?

You should actually be able to use either extension -- both can be mapped to your own custom IHttpHandler.

If I had to pick one to use, I'd probably go with a .ashx extension.  One reason for this is that there are no built-in .ashx end-points in ASP.NET -- whereas there are a few .axd ones (for example: the new webresources.axd).  So going with a .ashx reduces the chance of a naming conflict. 

.ashx files also now have intellisense support in VS 2005 -- so that makes building them easier as well.

Hope this helps,

Scott