app_jsdt Module

Daniel-Constantin Mierla

asipto.com

Edited by

Daniel-Constantin Mierla


Table of Contents

1. Admin Guide
1. Overview
2. Dependencies
2.1. Kamailio Modules
2.2. External Libraries or Applications
3. Parameters
3.1. load (str)
4. Functions
4.1. jsdt_dofile(path)
4.2. jsdt_dostring(script)
4.3. jsdt_run(function, params)
4.4. jsdt_runstring(script)
5. RPC Commands
5.1. app_jsrt.reload
6. Example of usage

List of Examples

1.1. Set load parameter
1.2. jsdt_dofile usage
1.3. jsdt_dostring usage
1.4. jsdt_run usage
1.5. jsdt_runstring usage

Chapter 1. Admin Guide

1. Overview

This module allows executing JavaScript scripts from config file. It exports all KEMI functions to JavaScript in order to access the current processed SIP message. These functions are within JavaScript object 'KSR'.

It includes the Duktape JavaScript engine (http://www.duktape.org), which is a fast and easy to embed JavaScript interpreter. Exported API from SIP router to JavaScript is documented in the dokuwiki.

The module has two JavaScript contexts:

  • first is used for functions jsdt_dofile() and jsdt_dostring().

  • second is used for function jsdt_run() and parameter 'load'. Therefore jsdt_run() cannot execute functions from scripts loaded via jsdt_dofile() in config. This is kind of caching mode, avoiding reading file every time, but you must be sure you do not have someting that is executed by default and requires access to SIP message. This environment is also used by KEMI framework for the config SIP routing functions.

2. Dependencies

2.1. Kamailio Modules

The following modules must be loaded before this module:

  • none.

2.2. External Libraries or Applications

The following libraries or applications must be installed before running Kamailio with this module loaded:

  • libm - the math library (part of standard system libraries - it is needed to complile embedded Duktape JS interpreter).

3. Parameters

3.1. load (str)

Set the path to the JavaScript file to be loaded at startup. Then you can use jsdt_run(function, params) to execute a function from the script at runtime. If you use it for KEMI configuration, then it has to include the requited functions.

Default value is null.

Example 1.1. Set load parameter

...
modparam("app_jsdt", "load", "/usr/local/etc/kamailio/js/myscript.js")
...

4. Functions

4.1.  jsdt_dofile(path)

Execute the JS script stored in 'path'. The parameter can be a string with pseudo-variables evaluated at runtime.

Example 1.2. jsdt_dofile usage

...
jsdt_dofile("/usr/local/etc/kamailio/js/myscript.js");
...

4.2.  jsdt_dostring(script)

Execute the Lua script stored in parameter. The parameter can be a string with pseudo-variables.

Example 1.3. jsdt_dostring usage

...
if(!jsdt_dostring('KSR.dbg("test message\n")'))
{
    xdbg("SCRIPT: failed to execute js script!\n");
}
...

4.3.  jsdt_run(function, params)

Execute the JS function 'func' giving params as parameters. There can be up to 3 string parameters. The function must exist in the script loaded at startup via parameter 'load'. Parameters can be strings with pseudo-variables that are evaluated at runtime.

Example 1.4. jsdt_run usage

...
if(!jsdt_run("js_append_fu_to_reply"))
{
    xdbg("SCRIPT: failed to execute js function!\n");
}
...
jsdt_run("js_funcx", "$rU", "2");
...

4.4.  jsdt_runstring(script)

Execute the JS script stored in parameter. The parameter can be a string with pseudo-variables. The script is executed in JS context specific to loaded JS files at startup.

Example 1.5. jsdt_runstring usage

...
if(!jsdt_runstring('KSR.dbg("Hello World from $fU\n")'))
{
    xdbg("failed to execute js script!\n");
}
...

5. RPC Commands

5.1.  app_jsrt.reload

Marks the need to reload the js script. The actual reload is done by every working process when the next call to jsrt_run() function or KEMI config is executed.

Name: app_jsdt.reload

Parameters: none

Example:

...
kamcmd app_jsrt.reload
...

6. Example of usage

Create your JS script and stored on file system, say: '/usr/local/etc/kamailio/js/myscript.js'.

...
function sr_append_fu_to_reply()
{
	KSR.hdr.append_to_reply("P-From: " + KSR.pv.get("$fu") + "\r\n");
}
...

Load the script via parameter 'load' and execute function via jsdt_run(...).

...
modparam("app_jsdt", "load", "/usr/local/etc/kamailio/js/myscript.js")
...
request_route {
    ...
    if(!jsdt_run("sr_append_fu_to_reply"))
    {
        xdbg("SCRIPT: failed to execute js function!\n");
    }
    ...
}
...