21 Preventing Service Broker System Overload

This chapter explains how to protect Oracle Communications Service Broker from overload.

Understanding Overload Protection

In some cases, such as traffic peaks or unexpected failure of network entities, the load on Service Broker modules can increase significantly. This can cause a situation known as system overload, where Service Broker modules have insufficient resources to handle new sessions. If overload is not handled correctly, the system can crash, and critical data can be lost.

To handle increased amounts of traffic without damaging operations of the entire system, Service Broker provides an overload protection mechanism. This mechanism operates in Processing Domains, where you can define criteria for overload detection and configure how Service Broker behaves if system overload occurs.

To activate overload protection you have to perform the following steps:

1. Identify key overload indicators

   You can choose any of the many counters and gauges provided by Service Broker to serve as key overload indicators. When you later set these gauges and counters to be key overload indicators, Service Broker triggers overload prevention based on the values measured by these gauges and counters.

   It is recommended to identify at least the following two system level measurements as your key overload indicators:

   • SystemCountersRuntimeMBean.SessionGauge: A gauge measuring the number of active sessions currently handled by Service Broker.

   • SystemCountersRuntimeMBean.InitialRequestCount: A counter measuring the rate in which Service Broker receives new sessions.

   Note that identifying a counter or a gauge as a key overload indicator does not yet make it a key overload indicator. You define the gauges and counters as key overload indicators in step 3.

2. Define thresholds for the identified indicators

   For each key overload indicator (that is gauge or counter) that you identified in the step 1, you need to define an upper threshold. When a key overload indicator crosses this threshold, Service Broker activates overload protection.

3. Define key overload indicators

   You need to define the key overload indicators that you identified in step 1, as valid and active key overload indicators

4. Configure overload protection behavior

   When Service Broker identifies overload (that is, when any of the key overload indicators has crossed its threshold), it continues handling active sessions but stops accepting new sessions. In this step, you can configure how Service Broker responds to SIP and Diameter network entities that attempt to establish sessions during a system overload. For example, you can define the type of error and value of the SIP Retry-After header field that Service Broker uses to respond to newly established SIP sessions.

Configuring Overload Protection

You can configure overload protection using either the Administration Console or the Service Broker configuration MBeans.

For a description of the overload protection configuration, see the discussion on managing the Service Broker processing tier in Oracle Communications Service Broker Processing Domain Configuration Guide.