This extension must override the methods that begin with "supports" that describe translator capabilities. For all the available translator capabilities please see this.

The most common example is adding support for a scalar function – this requires both declaring that the translator has the capability to execute the function and often modifying the SQL Translator to translate the function appropriately for the source.

Another common example is turning off unsupported SQL capabilities (such as outer joins or subqueries) for less sophisticated JDBC sources.

The JDBCExcecutionFactory provides several methods to modify the command and the string form of the resulting syntax before it is sent to the JDBC driver, including:

The JDBCExecutionFactory provides several methods to modify the java.sql.Statement and java.sql.ResultSet interactions, including:

See User Defined Functions for adding new functions to Teiid. This example will show you how to declare support for the function and modify how the function is passed to the data source.

Following is a summary of all coding steps in supporting a new scalar function:

There is a capabilities method getSupportedFunctions() that declares all supported scalar functions.

package my.connector;
            
import java.util.ArrayList;
import java.util.List;

public class ExtendedJDBCExecutionFactory extends JDBCExecutionFactory {
    @Override
    public List getSupportedFunctions() {
        List supportedFunctions = new ArrayList();
        supportedFunctions.addAll(super.getSupportedFunctions());
        supportedFunctions.add("ABS"); 
        return supportedFunctions;
    }
}

In general, it is a good idea to call super.getSupportedFunctions() to ensure that you retain any function support provided by the translator you are extending.

This may be all that is needed to support a Teiid function if the JDBC data source supports the same syntax as Teiid. The built-in SQL translation will translate most functions as: “function(arg1, arg2, …)”.

public class ModFunctionModifier implements FunctionModifier {
          
    public List translate(Function function) {
        List parts = new ArrayList();
        parts.add("(");        
        Expression[] args = function.getParameters();
        parts.add(args[0]);
        parts.add(" % "); 
        parts.add(args[1]);
        parts.add(")");    
        return parts;
    }
}

public class ExtendedJDBCExecutionFactory extends JDBCExecutionFactory
              
	@Override
	public void start() {
	    super.start();
	    
	    // register functions.
	    registerFunctionModifier("abs", new MyAbsModifier()); 
	    registerFunctionModifier("concat", new AliasModifier(“concat2”)); 
	}
}

Once you have developed an extension to the JDBC translator, you must install it into the Teiid Server. The process of packaging or deploying the extended JDBC translators is exactly as any other other translator. Since the RDMS is accessible already through its JDBC driver, there is no need to develop a resource adapter for this source as JBoss AS provides a wrapper JCA connector (DataSource) for any JDBC driver.