DB Manager Service

This document describes the DB Manager Service and the DB interface.

Overview

Keeping data of all bundles in a common database may lead to significant losses if the framework and its storage crash. The DB Manager service allows for:

• Using of custom databases placed at different locations;
• Writing data on a volatile file system with fast write access and then transferring it altogether to a persistent storage.

For more information check the Developer Guide – Database.

Registering Bundle

This service is provided by Core Database Bundle.

DB Interface

The DB interface allows access to a tree database, where each bundle has its own branch. Bundles are prevented from accessing data, located in another branch. A database is an com.prosyst.mbs.services.db.DB instance, which keeps data in nodes in the form of name/value pairs.

As described in Developer Guide there are two types of databases that may be used:

• Main DB – Holds the data of every bundle using it in a separate root, whose data can be accessed directly only by the bundle owning it. Other bundles can only read the content of the bundle-specific node and only in case they access the main DB as custom with alias "<main>". For more information see Saving Main DBs.
• Custom DB – Holds data, which can be structured in a custom manner and can be accessed and modified by any bundle if known the database alias and/or root directory. For more information see Managing Custom DBs.