Ns_ConnReturnOpen(3aolserver)				   AOLserver Library Procedures 			     Ns_ConnReturnOpen(3aolserver)

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NAME

       Ns_ConnReturnOpenChannel, Ns_ConnReturnOpenFd, Ns_ConnReturnFdEx, Ns_ConnReturnOpenFile - Routines to send open file content

SYNOPSIS

       #include "ns.h"
       int

       int
       Ns_ConnReturnOpenChannel(conn, status, type, chan, len)

       int
       Ns_ConnReturnOpenFd(conn, status, type, fd, len)

       int
       Ns_ConnReturnOpenFdex(conn, status, type, fd, off, len)

       int
       Ns_ConnReturnOpenFile(conn, status, type, fp, len)

ARGUMENTS

       Tcl_Channel   chan   (in)      Pointer to Tcl_Channel open for read.

       Ns_Conn	     conn   (in)      Pointer to open connection.

       FILE	     *fp    (in)      Pointer to stdio FILE open for read.

       off_t	     off    (in)      Seek offset.

       int	     fd     (int)     File descriptor open for read.

       int	     status (in)      HTTP status code.

       char	     *type  (in)      Pointer to mimetype string.
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DESCRIPTION

       These  routines	are  used  to generate complete responses, including headers, status codes, content types, and the content copied from the
       given open file. They all return a status code which is NS_OK if the response was sent or NS_ERROR if an underlying call to sent  the  con-
       tent  failed.  The response will include the given HTTP status code, a content-type header with the given type, and a content-length header
       with the length specified by len.  No character output encoding or gzip compression is performed on the content.

       For Ns_ConnReturnOpenFdEx, copying begins at the offset specified by the off argument Otherwise, these routines copy from the current  read
       offset  in  the	underlying  open  file.   No attempt is made to serialize access to the underlying object so independent open file objects
       and/or mutex locking is necessary if the same file is being sent simultaneously to multiple clients.

NOTES

       Windows Support
	      The Ns_ConnReturnOpenFdEx routine is not currently supported on Windows.	When called on Windows, it will always return NS_ERROR.

       Truncated Result
	      The server will construct a content-length header based on the given len argument. However, the server will send the content with an
	      underlying call to a cooresponding Ns_ConnSend function, e.g., Ns_ConnSendFd for Ns_ConnReturnOpenFd.  These functions will send the
	      requested content or all remaining content in the open file if less bytes are avilable without reporting an error due to	the  trun-
	      cated  response.	 As  the headers will have already been flushed before sending the content in this case, the content-length header
	      will not be consistent with the actual bytes sent.  If it is not possible to ensure the remaining bytes will be equal or greater	to
	      the requested bytes to send, it is possible to specify -1 for len to supress the content-length header entirely.	Most browsers will
	      accept this resonse and simply calculate the length from the bytes receieved up until the socket is closed.

       Performance Consideration
	      As mentioned, these routines use underlying Ns_ConnSendFd style routines to copy and send the content from open files.  This is  not
	      the  approach  used  by  the  builtin  file-serving  code (aka the "fastpath").  The fastpath operates with filenames, not open file
	      objects, and maintains a cached of pre-read or memory mapped regions to accelerate the common case  of  rapidly  sending	reasonably
	      sized content to multiple, simultaneous clients.	The Ns_ConnReturnFile routine utilizes the underlying fastpath and thus could be a
	      faster means to send static files than directly opening files and calling these API's.

SEE ALSO

       Ns_ConnReturnFile(3), Ns_ConnFlush(3), Ns_ConnSendFd(3), Ns_ConnReturnData(3)

KEYWORDS

       connnection, response, file

AOLserver								4.0					     Ns_ConnReturnOpen(3aolserver)