what is .asmx in .wsdl file

[Krthekeyan Suriyanarayanan]

hi all,
I had received a .wsdl file from my service provider . when I make the 
request using that .wsdl file

I am getting the following error
********************************
HTTP operation 'POST' could not be performed on URL 
'/TravelService/HotelsService.asmx' due to an error:

A connection with the server could not be established

and when I say ok

I get one more message.

The web service has sent an empty response!

what is this.asmx means how do i resolve the problem.

thanks in advance....