16.59. Example Use of Connector Components

As an example, consider if we wanted ModeShape to give us access through JCR to the information contained in a relational database. We first have to develop a connector that allows us to interact with relational databases using JDBC. That connector would contain a JdbcAccessSource class that implements RepositorySource , and that has the various JavaBean properties for setting the name of the driver class, URL, username, password, and other properties. If we add a JavaBean property defining the JNDI name, our connector could look in JNDI to find a JDBC DataSource instance, perhaps already configured to use connection pools.

Our new connector might also have a JdbcAccessConnection Java class that implements the RepositoryConnection interface. This class would probably wrap a JDBC database connection, and would implement the execute(...) method such that the nodes exposed by the connector describe the database tables and their contents. For example, the connector might represent each database table as a node with the table's name, with properties that describe the table (e.g., the description, whether it is a temporary table), and with child nodes that represent rows in the table.

To use our connector in an application that uses ModeShape, we would need to create an instance of the JdbcAccessSource for each database instance that we want to access. If we have 3 MySQL databases, 9 Oracle databases, and 4 PostgreSQL databases, then we'd need to create a total of 16 JdbcAccessSource instances, each with the properties describing a single database instance. Those sources are then available for use by ModeShape components, including the JCR implementation.