# &adminguide;

## Overview

This module can be used to efficiently run Python code directly from the &osips; script, without executing the python interpreter.

The module provides the means to load a python module and run its functions. Each function has to receive the SIP message as parameter, and optionally some extra arguments passed from the script.

In order to run Python functions, one has to load the module that contains them, by specifying the script name using the script_name parameter. The module has to contain the following components:

- A class that contains all the methods that can be invoked from the script.

- A method within the class that is called when a SIP child is created. The method should receive an integer parameter, which represents the rank of the child, and must return 0 or positive in case the function was executed successfully, or negative otherwise. The name of this method is specified by the child_init_method parameter.

- A global function that initializes the Python module and returns an object from the class whose functions will be invoked by the script. The name of the global function is indicated by the mod_init_method parameter.

A minimal example of a Python script that satisfies these requirements is:

    	def mod_init():
    		return SIPMsg()

    	class SIPMsg:
            def child_init(self, rank):
    	        return 0

A function from the object returned above can be executed from the script using the python_exec() script function. The python method has to receive the following parameters:

- The SIP message, that has the structure detailed below

- Optionally, a string passed from the script

The SIP message received as parameter by the function has the following fields and methods:

- Type - the type of the message, either SIP_REQUEST or SIP_REPLY

- Method - the method of the message

- Status - the status of the message, available only for replies

- RURI - the R-URI of the message, available only for requests

- src_address - the (IP, port) tuple representing source address of the message

- dst_address - the (IP, port) tuple representing the destination address (&osips; address) of the message

- copy() - copies the current SIP message in a new object

- rewrite_ruri() - changes the R-URI of the message; available only for requests

- set_dst_uri() - sets the destination URI of the message; available only for requests

- getHeader() - returns the header of a message the destination address (&osips; address) of the message

- call_function() - calls a function from the script

## Dependencies

### &osips; Modules

The following modules must be loaded before this module:

- None.

### External Libraries or Applications

The following libraries or applications must be installed before running &osips; with this module loaded:

- python-dev - provides the Python bindings.

## Exported Parameters

### `script_name` (string)

The script that contains the Python module.

Default value is /usr/local/etc/opensips/handler.py.

#### Set `script_name` parameter

    ...
    modparam("python", "script_name", "/usr/local/bin/opensips_handler.py")
    ...

### `mod_init_function` (string)

The method used to initialize the Python module and return the object.

Default value is mod_init.

#### Set `mod_init_function` parameter

    ...
    modparam("python", "mod_init_function", "module_initializer")
    ...

### `child_init_method` (string)

The method called for each child process.

Default value is child_init.

#### Set `child_init_method` parameter

    ...
    modparam("python", "child_init_method", "child_initializer")
    ...

## Exported Functions

### `python_exec(method_name [, extra_args])`

Thhis function is used to execute a method from the Python module loaded.

This function can be used from REQUEST_ROUTE, ONREPLY_ROUTE, FAILURE_ROUTE and BRANCH_ROUTE.

Meaning of the parameters is as follows:

- method_name - name of the method called

- extra_args(optional) - extra arguments that can be passed from the script to the python function.