Delegating Translator

In some instances you may wish to extend several differnt kinds of translators with the same functionality. Rather than create separate subclasses for each extension, you can use the delegating translator framework which provides you with a proxying mechanism to override translator behavior. It implement a delegating translator, your common translator logic should be added to a subclass of BaseDelegatingExecutionFactory where you can override any of the delegation methods to perform whatever logic you want.

Example BaseDelegatingExecutionFactory Subclass
public class MyTranslator extends BaseDelegatingExecutionFactory<Object, Object> {

    public Execution createExecution(Command command,
            ExecutionContext executionContext, RuntimeMetadata metadata,
            Object connection) throws TranslatorException {
        if (command instanceof Select) {
            //modify the command or return a different execution

        //the super call will be to the delegate instance
        return super.createExecution(command, executionContext, metadata, connection);

You will bundle and deploy your custom delegating translator is just like any other custom translator development. To you use your delegating translator in a vdb, you define a translator override that wires in the delegate.

Example Translator Override
<translator type="custom-delegator" name="my-translator">

     <property value="delegateName" name="name of the delegate instance"/>

     <!-- any custom properties you may have on your custom translator -->


From the previous example the translator type is custom-delegator. Now my-translator can be used as a translator-name on a source and will proxy all calls to whatever delegate instance you assign.

Note that the delegate instance can be any translator instance, whether configured by it’s own translator entry or just the name of a standard translator type.

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