[teiid-dev] Connector supplied metadata

[Steven Hawkins]

https://jira.jboss.org/jira/browse/TEIID-684 covers allowing connectors to supply metadata.  An initial check-in of this feature was added last night.  For those that are interested have a look at TestVDBLessExecution in the test-integration module.  

Through just a ConfigurationInfo.def file:

<VDB>
    <VDBInfo>
        <Property Name="Name" Value="VDBLess" />
        <Property Name="Version" Value="4" />
        <Property Name="UseConnectorMetadata" Value="true" />
    </VDBInfo>
    <Model>
        <Property Name="Name" Value="SummitData" />
        <ConnectorBindings>
            <Connector Name="Text Connector" />
        </ConnectorBindings>
    </Model>
    <ConnectorBindings>
        <Connector Name="Text Connector" ComponentType="Text File Connector">
            <Properties>
                <Property Name="Immutable">true</Property>
                <Property Name="DescriptorFile">src/test/resources/vdbless/TextDescriptor.txt</Property>
            </Properties>
        </Connector>
    </ConnectorBindings>
</VDB>

The text connector supplies the metadata for the SummitData model (through the TextDescriptor file).  I'll have the wiring added for the JDBC connector shortly along with additional metadata features, such as keys and procedures.

Note that the changes have heavily refactored the metadata module.  The intention is for 6.2 Designer to specifically fork the the 6.1 version of the metadata code to provide their own implementation of the QueryMetadataInterface with their legacy usage of MetadataRecords.  This does not require any api level changes on their part or changes to the current preview integration mechanism.  There are currently no plans to incorporate this work into Designer as this is currently envisioned for ease of use of stand-alone Teiid.

An issue that is open for discussion is that the connector api now exposes the MetadataRecord objects as well as it the MetadataObject interfaces (Group, Element, etc).  A case could be made for expanding the MetadataObject interfaces to include getters and setters for all relevant fields on MetadataRecords (there are currently many fields that the user doesn't need to modify that are only used by index logic or are handled by the MetadataFactory).  We still however would need to have separate implementations of the interfaces since the Designer preview feature would still provide metadata through its QMI in the from of legacy MetadataRecords.  If we do expand the interfaces in this way, we would also probably want to add logic to ensure that no modifications can be performed when the records are supplied as RuntimeMetadata.

One warning that should be added is that since the metadata is non-persistent direct usage of uuid values in system tables should be discouraged.

Steve