O Scaling Out Your Data Grid Aggregations Linearly

Example O-1 Trade Object Defining Three Properties

package com.tangosol.examples.coherence.data;


import com.tangosol.util.Base;
import com.tangosol.util.ExternalizableHelper;
import com.tangosol.io.ExternalizableLite;

import java.io.IOException;
import java.io.NotActiveException;
import java.io.DataInput;
import java.io.DataOutput;


/**
* Example Trade class
*
* @author erm 2005.12.27
*/
public class Trade
        extends Base
        implements ExternalizableLite
    {
    /**
    * Default Constructor
    */
    public Trade()
        {
        }

    public Trade(int iId, double dPrice, String sSymbol)
        {
        setId(iId);
        setPrice(dPrice);
        setSymbol(sSymbol);
        }

    public int getId()
        {
        return m_iId;
        }

    public void setId(int iId)
        {
        m_iId = iId;
        }

    public double getPrice()
        {
        return m_dPrice;
        }

    public void setPrice(double dPrice)
        {
        m_dPrice = dPrice;
        }

    public String getSymbol()
        {
        return m_sSymbol;
        }

    public void setSymbol(String sSymbol)
        {
        m_sSymbol = sSymbol;
        }

    /**
    * Restore the contents of this object by loading the object's state from the
    * passed DataInput object.
    *
    * @param in the DataInput stream to read data from to restore the
    *           state of this object
    *
    * @throws IOException        if an I/O exception occurs
    * @throws NotActiveException if the object is not in its initial state, and
    *                            therefore cannot be deserialized into
    */
    public void readExternal(DataInput in)
            throws IOException
        {
        m_iId     = ExternalizableHelper.readInt(in);
        m_dPrice  = in.readDouble();
        m_sSymbol = ExternalizableHelper.readSafeUTF(in);
        }

    /**
    * Save the contents of this object by storing the object's state into the
    * passed DataOutput object.
    *
    * @param out the DataOutput stream to write the state of this object to
    *
    * @throws IOException if an I/O exception occurs
    */
    public void writeExternal(DataOutput out)
            throws IOException
        {
        ExternalizableHelper.writeInt(out, m_iId);
        out.writeDouble(m_dPrice);
        ExternalizableHelper.writeSafeUTF(out, m_sSymbol);
        }

    private int    m_iId;
    private double m_dPrice;
    private String m_sSymbol;
    }

Example O-2 Mapping a cache-mapping to a caching-scheme with Unlimited Capacity

<?xml version="1.0"?>

<!DOCTYPE cache-config SYSTEM "cache-config.dtd">

<cache-config>
  <caching-scheme-mapping>
    <cache-mapping>
      <cache-name>*</cache-name>
      <scheme-name>example-distributed</scheme-name>
    </cache-mapping>
  </caching-scheme-mapping>

  <caching-schemes>
    <!-- 
    Distributed caching scheme.
    -->
    <distributed-scheme>
      <scheme-name>example-distributed</scheme-name>
      <service-name>DistributedCache</service-name>

      <backing-map-scheme>
        <class-scheme>
          <scheme-ref>unlimited-backing-map</scheme-ref>
        </class-scheme>
      </backing-map-scheme>

      <autostart>true</autostart>
    </distributed-scheme>

    <!-- 
    Backing map scheme definition used by all the caches that do 
    not require any eviction policies 
    -->
    <class-scheme>
      <scheme-name>unlimited-backing-map</scheme-name>

      <class-name>com.tangosol.util.SafeHashMap</class-name>
      <init-params></init-params>
    </class-scheme>
  </caching-schemes>
</cache-config>

Example O-3 Adding an Index to the Price Property

ReflectionExtractor extPrice  = new ReflectionExtractor("getPrice");
m_cache.addIndex(extPrice, true, null);

Example O-4 Perform a Parallel Aggregation Across all JVMs in the Grid

Double DResult;
DResult = (Double) m_cache.aggregate((Filter) null, new DoubleSum("getPrice"));