Programming Application Configuration Management

Purpose

When you deploy an application on the J2EE Engine, all application data, such as files, properties, and so on, is stored in the underlying database. The application configuration API, which the engine provides, enables you to access and manage the persistent data of your application programmatically.

Features

The J2EE Engine stores its persistent data in the database hierarchically.

Each application deployed on the server has its own subtree called a configuration, where the application-specific data is stored. The application configurations are isolated from one another, so that each application can only access its own subtree. The Configuration Manager is the module that manages the access to the configurations.

Each configuration may have child nodes called sub-configurations. The topmost node in the application configuration hierarchy is the root configuration.

The maximum hierarchy depth allowed for an application configuration is 12.

The configurations are identified by their name. You can also identify a configuration by an absolute path to the root configuration. The name of the root configuration is an empty string. For example, if the configuration C is a child of B, which is a child of A, which is a child of the root configuration, the absolute path to A is defined as A/B/C.

The maximum path name length allowed for an application configuration is (235 – [application display name]) characters.

The data in the configuration is stored as configuration entries. They can be of the following types:

·        Short, Integer, Long, Boolean, Double, String, byte[]

·        Objects implementing java.io.Serializable

·        Files (as File or as InputStream)

·        PropertySheet objects – they represent sets of properties including the definition of default values for these properties

Using the interfaces for application configuration management you can programmatically:

·        Connect to the Configuration Manager

·        Open a configuration in read or write mode

·        Access the application configuration root

·        Create a sub-configuration

·        Modify the application configuration

·        Handle exceptions

·        Register ConfigurationChangedListeners

·        Define application properties