---
name: "Ns_ConnFlush"
section: "3aolserver"
platform: "linux"
package: "aolserver4-dev"
version: "4.5.1-18.1"
release: "Debian 9 (Stretch)"
platforms: ["linux"]
url: "https://new.carta.tech/Ns_ConnFlush"
---

# Ns\_ConnFlush(3aolserver)

Flush content to an open connection

```

```

## NAME

Ns\_ConnFlush, Ns\_ConnFlushDirect - Flush content to an open connection

## SYNOPSIS

```
#include "ns.h"

int
Ns_ConnFlush(conn, buf, len, stream)

int
Ns_ConnFlushDirect(conn, buf, len, stream)
```

## ARGUMENTS

- 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.

  ```

  ```

## DESCRIPTION

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.

## EXAMPLE

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: %d0, i);
		Ns_ConnFlush(conn, buf, -1, 1);
	}
	Ns_ConnFlush(conn, "done!", 5, 0);
```

## SEE ALSO

Ns\_ConnSend(n), [Ns\_ConnClose(3)](/Ns_ConnClose/3.md), [Ns\_ConnSetRequiredHeaders(3)](/Ns_ConnSetRequiredHeaders/3.md), [Ns\_ConnQueueHeaders(3)](/Ns_ConnQueueHeaders/3.md)

## KEYWORDS

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