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'\" The Original Code is AOLserver Code and related documentation
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'\" The Initial Developer of the Original Code is America Online,
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'\" $Header: /cvsroot/aolserver/aolserver/doc/Ns_ConnFlush.3,v 1.1 2006/04/19 17:37:30 jgdavidson Exp $
'\"
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.TH Ns_ConnFlush 3aolserver 4.5 AOLserver "AOLserver Library Procedures"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
Ns_ConnFlush, Ns_ConnFlushDirect \- Flush content to an open connection
.SH SYNOPSIS
.nf
\fB#include "ns.h"\fR
.sp
int
\fBNs_ConnFlush\fR(\fIconn, buf, len, stream\fR)
.sp
int
\fBNs_ConnFlushDirect\fR(\fIconn, buf, len, stream\fR)
.SH ARGUMENTS
.AS Ns_Conn conn in
.AP char *buf in
Pointer to buffer to send.
.AP Ns_Conn conn in
Pointer to current connection.
.AP int len in
Length of bytes pointed to by \fIbuf\fR.
.AP int stream in
Boolean value to indicate a streamed response.
.BE

.SH DESCRIPTION
.PP
These routines support sending content to the client through the
connection's communcation driver.  They support generating both
complete single responses or streaming content through multiple
calls.  They both take a pointer to the current connection specified
by the \fIconn\fR argument and a pointer to content to send specified
by \fIbuf\fR of length \fIlen\fR.  If \fIlen\fR is negative, \fIbuf\fR
is assumed to be a null terminated string and \fIlen\fR is calculated
by \fBstrlen\fR.

.PP
The \fIstream\fR argument, if zero, indicates a single response
should be generated.  In this case, an appropriate \fIcontent-length\fR
header is generated, the content is sent, and the connection is
closed with \fBNs_ConnClose\fR.  If \fIstream\fR is not zero, the
call is assumed to be one of potential multiple calls which will
send content incrementally to the client.  Content streamed in this
case is sent either in \fIchunked\fR encoding mode for HTTP/1.1
clients or directly, without a \fIcontent-length\fR as was common
in pre-HTTP/1.1 applications.  Applications which stream content
should be sure to make a final call \fBNs_ConnFlush\fR or
\fBNs_ConnFlushDirect\fR with \fIstream\fR set to zero to correctly
flush and close the connection.

.PP
The \fBNs_ConnFlush\fR and \fBNs_ConnFlushDirect\fR differ in their
treatment of the given content before sending.  \fBNs_ConnFlushDirect\fR
does not alter the content in anyway, treating is as an arbitrary 
array of bytes.  \fBNs_ConnFlush\fR assumes the content is UTF-8 text, e.g.,
the result of an ADP page execution. In this case, if the connection
has an associated output encoding set with the \fBNs_ConnSetEncoding\fR
routine, it will be used to encode the content in the requested
character set (e.g., from UTF-8 to iso8859-1).  In addition, if the
server has gzip compression enabled, the \fBnszlib\fR module is loaded,
the connection has been marked for gzip compression with the
\fBNs_ConnSetGzipFlag\fR, and the size of the output data is greater
than the server configured minimun gzip compression size, the content
will be compressed and an appropriate header will be generated for
the client.  Gzip compression is not supported when content is streamed
to the client.

.PP
The first call to \fBNs_ConnFlush\fR or \fBNs_ConnFlushDirect\fR
for a connection, in stream or single response mode, will result
in appropriate headers being constructed and sent first before any
user data.  These headers include the basic headers constructed via
\fBNs_ConnSetRequiredHeaders\fR plus any additional application
specific headers queued for output via \fBNs_ConnSetHeaders\fR or
\fBNs_ConnCondSetHeaders\fR.  The \fBNs_ConnFlush\fR routine may
add additional headers as needed to specify \fIchunked\fR and/or
\fIgzip\fR encoding.

.SH EXAMPLE
The following example generates a simple text response:

.CS
	Ns_ConnSetStatus(conn, 200);
	Ns_ConnSetType(conn, "text/plain");
	Ns_ConnFlush(conn, "Hello", 5, 0);
.CE

The following example demonstrates streaming:

.CS
	Ns_ConnSetStatus(conn, 200);
	Ns_ConnSetType(conn, "text/plain");
	for (i = 0; i < 10; ++i) {
		sprintf(buf, "stream: %d\n", i);
		Ns_ConnFlush(conn, buf, -1, 1);
	}
	Ns_ConnFlush(conn, "done!", 5, 0);
.CE

.SH "SEE ALSO"
Ns_ConnSend(n), Ns_ConnClose(3), Ns_ConnSetRequiredHeaders(3),
Ns_ConnQueueHeaders(3)

.SH KEYWORDS
connection i/o, gzip, stream, encoding, flush