io.stream

Question

does anyone know much about the io.stream i have a file on the client pc. i want to open that file and process it. fine easy. the catch is that there is quite a lot of business logic to be done on the file and its contents. the processing of this then will have to sit on the business layer. here is the catch. at the moment the business layer etc is all on the client pc but in the future the business and data access layer are going to be broken away and will be turned into a web service. if i pass the io.stream over to the web service will the processing of the file still work. i dont really want to have to read the whole file in and then pass the whole thing across as a string. so i suppose the crux. io.stream. does it pass across the whole file. is it like an xml stream. will the readstream work for a file that is on a remote computer cheers