In the Java interface there is one package, com.asterdata.ncluster.scalar, for the user defined scalar functions. This package contains one function interface called ScalarFunction. There is one package, com.asterdata.ncluster.aggregator, for the user defined aggregate functions. This package contains two function interfaces. They are NonDecomposableAggregatorFunction and DecomposibleAggregatorFunction.
In this section we show how to implement user defined scalar functions and user defined aggregate functions using these interfaces.