demos/dimensions/src/main/java/com/datatorrent/demos/dimensions/generic/GenericDimensionComputation.java

package com.datatorrent.demos.dimensions.generic;

import com.datatorrent.lib.statistics.DimensionsComputation;

import com.datatorrent.api.Context;
import com.datatorrent.api.Context.OperatorContext;

/**
 * Performs dimensional computations given an event schema.
 * <p>
 * This class takes a schema description and uses that to generate aggregators internally during setup.  If schema does
 * not specify dimensions, then it generates aggregators for all combinations of keys.
 *
 * Schema can be specified as a JSON string with following keys.
 *
 *   fields: Map of all the field names and their types.  Supported types: java.lang.(Integer, Long, Float, Double, String)
 *   dimension: Array of dimensions with fields separated by colon, and time prefixed with time=.  Supported time units: MINUTES, HOURS, DAYS
 *   aggregates: Fields to aggregate for specified dimensions.  Aggregates types can include: sum, avg, min, max
 *   timestamp: Name of the timestamp field.  Data type should be Long with value in milliseconds since Jan 1, 1970 GMT.
 *
 * Example JSON schema for Ads demo:
 *
 *   {
 *     "fields": {"publisherId":"java.lang.Integer", "advertiserId":"java.lang.Integer", "adUnit":"java.lang.Integer", "clicks":"java.lang.Long", "price":"java.lang.Long", "cost":"java.lang.Double", "revenue":"java.lang.Double", "timestamp":"java.lang.Long"},
 *     "dimensions": ["time=MINUTES", "time=MINUTES:adUnit", "time=MINUTES:advertiserId", "time=MINUTES:publisherId", "time=MINUTES:advertiserId:adUnit", "time=MINUTES:publisherId:adUnit", "time=MINUTES:publisherId:advertiserId", "time=MINUTES:publisherId:advertiserId:adUnit"],
 *     "aggregates": { "clicks": "sum", "price": "sum", "cost": "sum", "revenue": "sum"},
 *     "timestamp": "timestamp"
 *   }

 *
 * @displayName Generic Dimension Computation
 * @category Math
 * @tags dimension, aggregation
 *
 */
public class GenericDimensionComputation extends DimensionsComputation<GenericEvent, GenericAggregate>
{
  public void setSchema(EventSchema schema)
  {
    DimensionsGenerator gen = new DimensionsGenerator(schema);
    setAggregators(gen.generateAggregators());
  }


  @Override
  public void setup(OperatorContext context)
  {
    // hack begin!
    // this hack should be removed when we have application level properties - talk to Sasha/Chetan.
    try {
      getAggregators();
    }
    catch (NullPointerException npe) {
      /* means that it's not properly initialized; so initialize it for app builder demo */
      setSchema(new SchemaConverter().getEventSchema());
    }
    // hack end!


    super.setup(context); //To change body of generated methods, choose Tools | Templates.
  }

}