Ns_ConnFlush(3) Flush content to an open connection

Other Alias



#include "ns.h"

Ns_ConnFlush(conn, buf, len, stream)

Ns_ConnFlushDirect(conn, buf, len, stream)


char    *buf    (in)
Pointer to buffer to send.
Ns_Conn    conn    (in)
Pointer to current connection.
int    len    (in)
Length of bytes pointed to by buf.
int    stream    (in)
Boolean value to indicate a streamed response.


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 conn argument and a pointer to content to send specified by buf of length len. If len is negative, buf is assumed to be a null terminated string and len is calculated by strlen.

The stream argument, if zero, indicates a single response should be generated. In this case, an appropriate content-length header is generated, the content is sent, and the connection is closed with Ns_ConnClose. If stream 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 chunked encoding mode for HTTP/1.1 clients or directly, without a content-length as was common in pre-HTTP/1.1 applications. Applications which stream content should be sure to make a final call Ns_ConnFlush or Ns_ConnFlushDirect with stream set to zero to correctly flush and close the connection.

The Ns_ConnFlush and Ns_ConnFlushDirect differ in their treatment of the given content before sending. Ns_ConnFlushDirect does not alter the content in anyway, treating is as an arbitrary array of bytes. Ns_ConnFlush 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 Ns_ConnSetEncoding 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 nszlib module is loaded, the connection has been marked for gzip compression with the Ns_ConnSetGzipFlag, 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.

The first call to Ns_ConnFlush or Ns_ConnFlushDirect 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 Ns_ConnSetRequiredHeaders plus any additional application specific headers queued for output via Ns_ConnSetHeaders or Ns_ConnCondSetHeaders. The Ns_ConnFlush routine may add additional headers as needed to specify chunked and/or gzip encoding.


The following example generates a simple text response:

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

The following example demonstrates streaming:

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


connection i/o, gzip, stream, encoding, flush