ASYNC Module

Daniel-Constantin Mierla

Edited by

Daniel-Constantin Mierla

Copyright © 2011-2016 asipto.com

Table of Contents

1. Admin Guide
1. Overview
2. Dependencies
2.1. Kamailio Modules
2.2. External Libraries or Applications
3. Parameters
3.1. workers (int)
4. Functions
4.1. async_route(routename, seconds)
4.2. async_sleep(seconds)
4.3. async_task_route(routename)

List of Examples

1.1. Set workers parameter
1.2. async_route usage
1.3. async_sleep usage
1.4. async_workers usage
1.5. async_task_route usage

Chapter 1. Admin Guide

Table of Contents

1. Overview
2. Dependencies
2.1. Kamailio Modules
2.2. External Libraries or Applications
3. Parameters
3.1. workers (int)
4. Functions
4.1. async_route(routename, seconds)
4.2. async_sleep(seconds)
4.3. async_task_route(routename)

1. Overview

This module provides asynchronous operations for handling SIP requests in the configuration file.

Async uses t_suspend() and t_continue() from the TM and TMX modules.

Note that after invoking the asynchronous operation, the processing will continue later in another application process. Therefore variables stored in private memory should not be used, try to use shared memory if you want to get values after the processing is resumed (e.g., $avp(...), $xavp(...), $shv(...), htable $sht(...)).

2. Dependencies

2.1. Kamailio Modules

The following modules must be loaded before this module:

  • tm - transaction management.

  • tmx - transaction management extensions.

2.2. External Libraries or Applications

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

  • None

3. Parameters

3.1. workers (int)

Number of worker processes to be started to handle the asynchronous tasks for async_route() and async_sleep().

Default value is 1.

Example 1.1. Set workers parameter 

...
modparam("async", "workers", 2)
...

4. Functions

4.1.  async_route(routename, seconds)

Simulate a sleep of 'seconds' and then continue the processing of the SIP request with the route[routename]. In case of internal errors, the function returns false, otherwise the function exits the execution of the script at that moment (return 0 behaviour).

The routename parameter can be a static string or a dynamic string value with config variables.

The sleep parameter represent the number of seconds to suspend the processing of a SIP request. Maximum value is 100. The parameter can be a static integer or a variable holding an integer.

Since the SIP request handling is resumed in another process, the config file execution state is practically lost. Therefore beware that the execution of config after resume will end once the route[routename] is finished.

This function can be used from REQUEST_ROUTE.

Example 1.2. async_route usage 

...
async_route("RESUME", "4");
...
route[RESUME] {
   send_reply("404", "Not found");
   exit;
}
...

4.2.  async_sleep(seconds)

Simulate a sleep of 'seconds' and then continue the processing of SIP request with the next action. In case of internal errors, the function returns false.

The sleep parameter represent the number of seconds to suspend the processing of SIP request. Maximum value is 100. The parameter can be a static integer or a variable holding an integer.

This function can be used from REQUEST_ROUTE.

Example 1.3. async_sleep usage 

...
async_sleep("4");
send_reply("404", "Not found");
exit;
...

4.3.  async_task_route(routename)

Continue the processing of the SIP request with the route[routename] in one of the processes from core asynchronous framework. The core parameter async_workers has to be set to enable asynchronous framework. The task is executed as soon as a process from asynchronous framework is idle, there is no wait time for the task like for async_route(...).

To enable the core asynchronous framework, you need to set the async_workers core parameter in the configuration file. See the core cookbook for more information.

Example 1.4. async_workers usage 

...
; Enable 8 worker processes used by async and other modules
async_workers=8
...


In case of internal errors, the function returns false, otherwise the function exits the execution of the script at that moment (return 0 behaviour).

The routename parameter can be a static string or a dynamic string value with config variables.

Since the SIP request handling is resumed in another process, the config file execution state is practically lost. Therefore beware that the execution of config after resume will end once the route[routename] is finished.

This function can be used from REQUEST_ROUTE.

Example 1.5. async_task_route usage 

...
async_task_route("RESUME");
...
route[RESUME] {
   t_relay();
   exit;
}
...