Overview of the Directory Eventing System
You can configure a DES for an SDX component that connects to one or more directories. DES provides two functions:
DES polls the directory periodically to determine changes that affect the configuration or operation of a particular component. If DES finds relevant changes, it automatically provides the changes to the component. However, if DES does not find relevant changes, it does not provide any information.
You must define a primary directory for SDX components that require access to a directory. You can also define a list of secondary (backup) directories.
DES detects when a connection to the primary directory fails, and:
- Connects to the first available secondary directory in the specified list.
- Reverts to the primary directory when it becomes available.
If a connection to a secondary directory fails, DES:
- Connects to the primary directory if it is available.
- If the primary directory is unavailable, connects to the first available directory in the specified list.
DES is not a central service for all SDX components; rather, you configure a DES for an individual SDX component. The SDX component determines the format of the DES properties; each DES property begins with a variable <connectionPrefix>. This variable is a property prefix that depends on the SDX component and the directory to which it connects. See the documentation for a specific SDX component for information about this variable.
Some components have connections to multiple directories; consequently you must configure DES properties for each connection. For example, the SAE may use different directories for service, configuration, and subscriber information.