A: 

By explicit serialization you mean you just don't want to write the serialization code yourself?

If you pass json object with just simple properties (i.e. no nested objects, just string, number, date values) to a .asmx web service where the parameter to the method is a C# object with the same named fields.... then I think you will get automatic deserialization. No need for a client side proxy/web method etc.

James Gaunt
in my case, I need to pass user-defined class..
Alan
just try it, if the class is simple enough you might find it works, otherwise you need to write explicit serialization/deserialization code on the server, or use the proxy code that asp.net can generate for you on the client. There is no magic way to automatically serialize/deserialize arbitrarily complex objects between client/server.
James Gaunt
so in the general case - the answer to your question is just - No... sorry about that.
James Gaunt
I read about [DataContract] but it is in WCF only I think.Thank you anyway.
Alan