Byte serving

Byte serving is the process of sending only a portion of an HTTP/1.1 message from a server to a client. Clients which request byte-serving might do so in cases in which a large file has been only partially delivered and a limited portion of the file is needed in a particular range. Byte Serving is therefore a method of bandwidth optimization. [ [http://www.research.att.com/~bala/papers/h0vh1.html Key Differences between HTTP/1.0 and HTTP/1.1] "A typical example is a server's sending an entire (large) resource when the client only needs a small part of it. There was no way in HTTP/1.0 to request partial objects... HTTP/1.1 range requests allow a client to request portions of a resource."] In the HTTP/1.0 standard, clients were only able to request an entire document. By allowing byte-serving, clients may choose to request any portion of the resource. One advantage of this capability is when a large media file is being requested, and that media file is properly formatted, the client may be able to request just the portions of the file known to be of interest. This has been reported to work for some PDF files and clients in which a client may request a certain page, rather than the entire file. [ [http://www.searchpdf.com/id419.htm Linearization and Byte Serving Explained] ]

Other names for byte serving:
* Section 14.35.2 of RFC 2616 says the client makes "Range Retrieval Requests" when it makes a partial content request
* Clients make "range requests" [ [http://www.apacheweek.com/features/http11 Apache Week. HTTP/1.1 ] ] [ [http://www.research.att.com/~bala/papers/h0vh1.html Key Differences between HTTP/1.0 and HTTP/1.1] ]
* "Byte Range Serving" [ [http://www-1.ibm.com/support/docview.wss?uid=swg27003226 Byte Range Serving in Domino R5 Server] ]
* "Page on demand" [ [http://computing-dictionary.thefreedictionary.com/byte+serving byte serving definition of byte serving in the Free Online Encyclopedia ] ]

The use of the Chunked Transfer-Encoding is not byte-serving, but is instead method in which only a portion (or chunk) of data is sent by the server in an HTTP/1.1 session. [ [http://developers.sun.com/mobility/midp/questions/chunking/ HTTP Chunking] ] It is often used when a server knows that it will take a long time to complete a client's request, and so it sends only small chunks of data as the data is dynamically created. Byte serving and chunking are compatible with or without the presence of the other.

ee also

* RFC 2616 Section 3.12: Range Units
* HTTP status codes
* HTTP headers
* Content negotiation

References