1. A method for delivering an incomplete response from a Hypertext Transfer Protocol (HTTP) server to a client, comprising: receiving a file request in the HTTP server from the client for a file or a byte range of the file at the HTTP server, wherein the file request indicates whether the client is capable of using an incomplete response; determining in the HTTP server, based on the file request, whether the client is capable of using an incomplete response; and sending from the HTTP server to the client an incomplete response in response to determining that the client is capable of using an incomplete response if a full response including an entirety of the file or the byte range of the file is not available at the HTTP server and the file or the byte range of the file requested by the file request is partially available at the HTTP server; the incomplete response sent from the HTTP server including the partially available file or the partially available byte range of the file requested by the file request and a header indicating the file or the byte range of the file requested by the file request is partially available or a status code indicating the file or the byte range of the file requested by the file request is partially available.