Want to know some spec

You could write a Photoshop script to get the file into Photoshop using a socket connection.   To update the file on the web server you would need authorization and most like a ftp user id on that server to ftp a replacement file to the server.  I believe Adobe Bridge optional output module supports some sort of ftp connection to upload web photo galleries.

There is no feature like you want in Photoshop. Also Photoshop does not officially support network files.  What you want to do would most likely be easier to do using remote file system shares.