MessageQueue

Revision as of 14:15, 11 April 2013

The MessageQueues is a mechanism for organizing YATE's messages in different queues, identified by message name and some specified filters.

This article explains how to create and use a MessageQueue in Javascript.

How to create MessageQueue in Javascript

In JavaScript a MessageQueue can be created by calling Message.installHook() method.

Read the description of MessageQueue behaviour in messages page .

installHook parameters

• processCallback - function, optional. The method that should process the messages skipping the engine handlers list.
• msgName - string, mandatory. The message name for the queue filtering.
• workers - integer, mandatory. The number of workers that should be used for message processing.
• trapCallback - function, optional. The method that should be called when a queue overload is detected.
• trapCount - integer, mandatory if trapCallback is present. The number of messages in the queue when we should be alerted.
• filter - string, optional, can be repeated. Optional message filter. Should be in form 'name=value'.

Examples

1. Creates a MessageQueue for engine.timer message with one processing thread.

installHook("engine.timer",1);

2. Creates a MessageQueue for call.route message, who has called=123. Two processing threads will be created. When a message needs to be processed the callback method will be called.

installHook(callback,"call.route",2,"called=123");

3. The same behaviour as above only that the trapCallback method will be called when in the queue exists more than 50 unprocessed messages

installHook(callback,"call.route",2,trapCallback,50,"called=123");

When to use?

MessageQueue can be used:

• when you have a high number of a specific message that needs to be handled
• when handling a message implies sending more messages that need to be processed
• when you want to avoid using Yate's message queue

If you need to handle a specific message frequently or see that processing this message takes too long you might need to use a custom MessageQueue for that message.

See also

• Messages