This Aggregation Function is used to call a User Defined Aggregation (UDF Aggregation) that is implemented as a subclass of:

    com.solusi247.function.AggregationFunction247

The UDFAggregation247 component requires two parameters:

• UDF Class Name
  The name of the class that extends com.solusi247.function.AggregationFunction247.
• Parameter
  A parameter value passed to the UDF aggregation class.

Creating a UDF Aggregation Class

To create a custom aggregation function, you must:

1. Create a Java class that extends:

       com.solusi247.function.AggregationFunction247
       

2. Implement the following three abstract methods:
   1. call(Comparable data)

          public abstract void call(Comparable data);
                  

      Called for every incoming data value.
      Used to process each input record.
   2. getOutput()

      public abstract Comparable getOutput();
          

      Called when the aggregation result must be emitted.
      Returns the final aggregated value.
   3. cleanup()

          public abstract void cleanup();
          

      Called after each group of data is processed.
      Used to reset variables.

Inherited Methods from AggregationFunction247

The class also provides several useful methods:

1. public String getParameter()
   Returns the parameter passed to the aggregation object.
2. public int getInputField()
   Returns the index of the input field.
3. public int getOutputField()
   Returns the index of the output field.
4. public int getInputFieldType()
   Returns the data type of the input field.
5. public int getOutputFieldType()
   Returns the data type of the output field.
6. public List<String> getIncomingFields()
   Returns the list of field names from the incoming record.

Supported Field Types

Input and output fields can use the following types:

    FieldType.STRING
    FieldType.BYTE
    FieldType.SHORT
    FieldType.INT
    FieldType.LONG
    FieldType.FLOAT
    FieldType.DOUBLE
    FieldType.DATE
    FieldType.TIMESTAMP
    FieldType.OBJECT

Example: UDF Aggregation (Sum Function)

Below is an example of a custom aggregation that calculates the sum of numeric values.

   
   package plugins.aggregation;

    import com.solusi247.function.AggregationFunction247;


    public class MySum extends AggregationFunction247 {

        double sum=0;

        @Override
        public void call(Comparable data) {
            try{
                sum=sum+Double.parseDouble(data.toString());
            }catch(Exception e){

            }
        }

        @Override
        public Comparable getOutput() {
            return sum;
        }

        @Override
        public void cleanup() {
            sum=0;
        }

    } 
   

How the Example Works

1. Variable Initialization double sum = 0;
2. Processing Each Data Value
   The call() method adds the incoming value to sum.
   Example input values:

       10
       15
       5
   

   Processing:

       sum = 10 + 15 + 5 = 30
   

3. Returning the Result

       getOutput()
       

   Returns:

       30
   

4. Reset After Processing

       cleanup()
       

   Resets:

       sum = 0
   

   so the next group starts with a clean state.

Deploying the UDF Aggregation

To make the aggregation function appear in HGrid247 GUI:

• Compile the Java class.
• Package it into a JAR file.
• Place the JAR file into the plugins folder.

Example structure:

    HGrid247-3.5/
    ├── plugins/
    │     └── MySum.jar

After restarting HGrid247, the aggregation function will appear in the Aggregation Parameter dialog.

Required Dependency

Java-based plug-ins require the following library:

    HGrid247-3.5/
    ├── libCommon/
    │     └──  HGrid247CommonLib-3.5.jar