How to cope with sending large file to WebService?

I encounter the large file problem, when a flatfile transformed to XML format, the size will increase dramatically, once i had a file over 200M and when sending it to WebService, due to the host machine setting — size limit, timeout value, always failed the transfer. Even if the size limit and timeout value increased accordingly still cannot sending the large file through successfully.

Sometimes i got a error HTML message saying "Server Unavailable", but the host sever actually is running, and most time i got the error "Cannot write data to …..the transfer is aborted by host machine…"

But never has problem sending small files using the same channel.

How should i do to cope with large file size problem?

Thanks