This connector provides read-only access to the metadata (e.g., catalogs, schemas, table structures) of a relational database. The connector yields a content graph that looks like this:

/ (root node)
    + <catalog name> - one node for each accessible catalog in the database.
        + <schema name> - one node for each accessible schema in the catalog.
            + tables - a single node that is the parent of all tables in the schema.
            |   + <table name> - one node for each table in the schema.
            |      + <column name> - one node for each column in the table.
            + procedures - a single node that is the parent of all procedures in the schema.
                + <procedure name> - one node for each procedure in the schema.

The root, table, column, and procedure nodes contain additional properties that correspond to the metadata provide by the DatabaseMetaData class. In databases that do not support catalogs or schemas (or allow the empty string as a valid catalog or schema name, the value of the defaultCatalogName and/or defaultSchemaName properties will be used instead when determining the graph name.

To use this connector with the DNA JCR layer, you must import the JCR node types that this connector uses. These are bundled in the JAR for this connector at the path /org/jboss/dna/connector/meta/jdbc/nodeTypes.cnd. Please see the Getting Started Guide for detailed examples of how to import custom JCR node types.

The JdbcMetadataSource class provides a number of JavaBean properties that control its behavior:

One way to configure the JDBC metadata connector is to create JcrConfiguration instance with a repository source that uses the JdbcMetadataSource class. For example:

JcrConfiguration config = ...

config.repositorySource("Meta Store")

      .usingClass(JdbcMetadataSource.class)

      .setDescription("The database source for our content")

      .setProperty("dataSourceJndiName", "java:/MyDataSource")

      .setProperty("nameOfDefaultWorkspace", "default");

Of course, setting other more advanced properties would entail calling setProperty(...) for each. Since almost all of the properties have acceptable default values, however, we don't need to set very many of them.

Another way to configure the JDBC metadata connector is to create JcrConfiguration instance and load an XML configuration file that contains a repository source that uses the JdbcMetadataSource class. For example a file named configRepository.xml can be created with these contents:

<?xml version="1.0" encoding="UTF-8"?>

<configuration xmlns:dna="http://www.jboss.org/dna/1.0" xmlns:jcr="http://www.jcp.org/jcr/1.0">

    <!-- 

    Define the sources for the content.  These sources are directly accessible using the 

    DNA-specific Graph API.  In fact, this is how the DNA JCR implementation works.  You 

    can think of these as being similar to JDBC DataSource objects, except that they expose 

    graph content via the Graph API instead of records via SQL or JDBC. 

    -->

    <dna:sources jcr:primaryType="nt:unstructured">

        <!-- 

        The 'Meta Store' repository is a JDBC metadata repository with a single default 

        workspace (though others could be created, too).

        -->

        <dna:source jcr:name="Meta Store" 

                    dna:classname="org.jboss.dna.graph.connector.meta.jdbc.JdbcMetadataSource" 

                    dna:description="The database source for our content"

                    dna:dataSourceJndiName="java:/MyDataSource"

                    dna:defaultworkspaceName="default"/>    

    </dna:sources>

    

    <!-- MIME type detectors and JCR repositories would be defined below --> 

</configuration>

 

The configuration can then be loaded from Java like this:

JcrConfiguration config = new JcrConfiguration().loadFrom("/configRepository.xml");