<?xml version="1.0"?>

<!--
  Copyright (C) Nginx, Inc.
  -->

<!DOCTYPE module SYSTEM "../../../../dtd/module.dtd">

<module name="Module ngx_stream_js_module"
        link="/en/docs/stream/ngx_stream_js_module.html"
        lang="en"
        rev="8">

<section id="summary">

<para>
The <literal>ngx_stream_js_module</literal> module is used to implement
handlers in <link doc="../njs_about.xml">nginScript</link> —
a subset of the JavaScript language.
</para>

<para>
This module is not built by default, it should be compiled with
the nginScript module using the
<literal>--add-module</literal> configuration parameter:
<example>
./configure --add-module=<value>path-to-njs</value>/nginx
</example>
The <link url="http://hg.nginx.org/njs">repository</link>
with the nginScript module can be cloned with the following command
(requires <link url="https://www.mercurial-scm.org">Mercurial</link> client):
<example>
hg clone http://hg.nginx.org/njs
</example>
This module can also be built as
<link doc="../ngx_core_module.xml" id="load_module">dynamic</link>:
<example>
./configure --add-dynamic-module=<value>path-to-njs</value>/nginx
</example>
</para>

</section>


<section id="example" name="Example Configuration">

<para>
<example>
stream {
    js_include stream.js;

    js_set $foo foo;
    js_set $bar bar;

    server {
        listen 12345;

        js_preread qux;
        return     $foo;
    }

    server {
        listen 12346;

        js_access  xyz;
        proxy_pass 127.0.0.1:8000;
        js_filter  baz;
    }
}

http {
    server {
        listen 8000;
        location / {
            return 200 $http_foo\n;
        }
    }
}
</example>
</para>

<para>
The <path>stream.js</path> file:
<example>
var req = '';
var matched = 0;
var line = '';

function qux(s) {
    var n = s.buffer.indexOf('\n');
    if (n == -1) {
        return s.AGAIN;
    }

    line = s.buffer.substr(0, n);
}

function foo(s) {
    return line;
}

function bar(s) {
    var v = s.variables;
    s.log("hello from bar() handler!");
    return "foo-var" + v.remote_port + "; pid=" + v.pid;
}

// The filter processes one buffer per call.
// The buffer is available in s.buffer both for
// reading and writing.  Called for both directions.

function baz(s) {
    if (s.fromUpstream || matched) {
        return;
    }

    // Disable certain addresses.

    if (s.remoteAddress.match('^192.*')) {
        return s.ERROR;
    }

    // Read HTTP request line.
    // Collect bytes in 'req' until request
    // line is read.  Clear current buffer to
    // disable output.

    req = req + s.buffer;
    s.buffer = '';

    var n = req.search('\n');

    if (n != -1) {
        // Inject a new HTTP header.
        var rest = req.substr(n + 1);
        req = req.substr(0, n + 1);

        var addr = s.remoteAddress;

        s.log('req:' + req);
        s.log('rest:' + rest);

        // Output the result and skip further
        // processing.

        s.buffer = req + 'Foo: addr_' + addr + '\r\n' + rest;
        matched = 1;
    }
}

function xyz(s) {
    if (s.remoteAddress.match('^192.*')) {
        return s.ABORT;
    }
}
</example>
</para>

</section>


<section id="directives" name="Directives">

<directive name="js_access">
<syntax><value>function</value></syntax>
<default/>
<context>stream</context>
<context>server</context>

<para>
Sets an nginScript function which will be called at the
<link doc="stream_processing.xml" id="access_phase">access</link> phase.
</para>

</directive>


<directive name="js_filter">
<syntax><value>function</value></syntax>
<default/>
<context>stream</context>
<context>server</context>

<para>
Sets a data filter.
</para>

</directive>


<directive name="js_include">
<syntax><value>file</value></syntax>
<default/>
<context>stream</context>

<para>
Specifies a file that implements server and variable handlers in nginScript.
</para>

</directive>


<directive name="js_preread">
<syntax><value>function</value></syntax>
<default/>
<context>stream</context>
<context>server</context>

<para>
Sets an nginScript function which will be called at the
<link doc="stream_processing.xml" id="preread_phase">preread</link> phase.
</para>

</directive>


<directive name="js_set">
<syntax>
<value>$variable</value> <value>function</value></syntax>
<default/>
<context>stream</context>

<para>
Sets an nginScript function for the specified variable.
</para>

</directive>

</section>


<section id="properties" name="Session Object Properties">
<para>
Each stream nginScript handler receives one argument, a stream session object.
</para>

<para>
The session object has the following properties:

<list type="tag">

<tag-name><literal>remoteAddress</literal></tag-name>
<tag-desc>
client address, read-only
</tag-desc>

<tag-name><literal>eof</literal></tag-name>
<tag-desc>
a boolean read-only property, true if the current buffer is the last buffer
</tag-desc>

<tag-name><literal>fromUpstream</literal></tag-name>
<tag-desc>
a boolean read-only property,
true if the current buffer is from the upstream server to the client
</tag-desc>

<tag-name><literal>buffer</literal></tag-name>
<tag-desc>
the current buffer, writable
</tag-desc>

<tag-name><literal>variables{}</literal></tag-name>
<tag-desc>
nginx variables object, read-only
</tag-desc>

<tag-name><literal>OK</literal></tag-name>
<tag-desc>
the <literal>OK</literal> return code
</tag-desc>

<tag-name><literal>DECLINED</literal></tag-name>
<tag-desc>
the <literal>DECLINED</literal> return code
</tag-desc>

<tag-name><literal>AGAIN</literal></tag-name>
<tag-desc>
the <literal>AGAIN</literal> return code
</tag-desc>

<tag-name><literal>ERROR</literal></tag-name>
<tag-desc>
the <literal>ERROR</literal> return code
</tag-desc>

<tag-name><literal>ABORT</literal></tag-name>
<tag-desc>
the <literal>ABORT</literal> return code
</tag-desc>
</list>
</para>

<para>
The session object has the following methods:

<list type="tag">

<tag-name><literal>log(<value>string</value>)</literal></tag-name>
<tag-desc>
writes a sent <value>string</value> to the error log
</tag-desc>
</list>
</para>

</section>

</module>