ClassCastException in InvocableMap.ParallelAwareAggregator

Question

I am using InvocableMap.ParallelAwareAggregator to sort results set on cache server side. But I'm keep getting ClassCastException like below :
2008-02-14 17:33:28.603 Oracle Coherence DC 3.3.1/389p1 <Info> (thread=main, member=n/a): Connected to 10.5.235.162:9096
Exception in thread "main" com.tangosol.io.pof.PortableException (Remote: An exception occurred while processing a AggregateFilterRequest) (Wrapped: Failed request execution for DistributedService service on Member(Id=10, Timestamp=2008-02-14 17:21:38.86, Address=10.5.235.162:8089, MachineId=58530, Location=machine:docqa4,member:dvCache2)) java.lang.ClassCastException
at com.docview.test.SortByServerAggregator$SortingParallelAggregator.sortByDate(SortByServerAggregator.java:188)
at com.docview.test.SortByServerAggregator$SortingParallelAggregator.sortEntries(SortByServerAggregator.java:151)
at com.docview.test.SortByServerAggregator$SortingParallelAggregator.aggregate(SortByServerAggregator.java:133)
at com.tangosol.coherence.component.util.daemon.queueProcessor.service.DistributedCache.onAggregateFilterRequest(DistributedCache.CDB:74)
at com.tangosol.coherence.component.util.daemon.queueProcessor.service.DistributedCache$AggregateFilterRequest.run(DistributedCache.CDB:1)
at com.tangosol.coherence.component.util.DaemonPool$WrapperTask.run(DaemonPool.CDB:24)
at com.tangosol.coherence.component.util.DaemonPool$Daemon.onNotify(DaemonPool.CDB:49)
at com.tangosol.coherence.component.util.Daemon.run(Daemon.CDB:35)
at java.lang.Thread.run(Thread.java:534)
Any ideas ? I can see the messages in cache server logs which indicate the sorting is done and size of sorted entries on each cache server instance. But if trying to print out each entry, I will get ClassCastException.
Attached please see my codes as below :
==================================================
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.List;
import java.util.TreeSet;
import java.util.HashSet;
import java.util.ArrayList;
import com.tangosol.io.ExternalizableLite;
import com.tangosol.util.ExternalizableHelper;
import com.tangosol.util.InvocableMap;
import com.tangosol.util.ValueExtractor;
import com.tangosol.util.InvocableMap.Entry;
import com.tangosol.util.InvocableMap.EntryAggregator;
import com.tangosol.util.InvocableMap.ParallelAwareAggregator;
import com.tangosol.util.extractor.ReflectionExtractor;
import com.docview.query.Cache_Query_Constants;
import com.docview.util.SortUtils;
import com.docview.cache.MultiTagPubSearchCacheKey;
import com.docview.entity.MultiTagPubSearchCacheEntity;
public class SortByServerAggregator implements ParallelAwareAggregator, ExternalizableLite {
     private String sortFlag;
     private String ascDescFlag;
     public SortByServerAggregator(String sortFlag, String ascDescFlag) {
          this.sortFlag = sortFlag;
          this.ascDescFlag = ascDescFlag;
     public SortByServerAggregator() {
          super();
     public Object aggregate(Set entries) {
          return new SortingParallelAggregator(sortFlag, ascDescFlag).aggregate(entries);
     public Object aggregateResults(Collection resultObjects) {
          return mergeMultipleResults(resultObjects);
     public EntryAggregator getParallelAggregator() {
          return new SortingParallelAggregator(sortFlag, ascDescFlag);
     public void readExternal(DataInput input) throws IOException {
          sortFlag = ExternalizableHelper.readSafeUTF(input);
          ascDescFlag = ExternalizableHelper.readSafeUTF(input);
     public void writeExternal(DataOutput output) throws IOException {
          ExternalizableHelper.writeSafeUTF(output, sortFlag);
          ExternalizableHelper.writeSafeUTF(output, ascDescFlag);
     private List mergeMultipleResults(Collection resultObjects) {
          ArrayList list = new ArrayList();
          Iterator iter = resultObjects.iterator();
          while (iter.hasNext()) {
               ParallelResultObject result = (ParallelResultObject)iter.next();
               list.addAll(result.generateResultList());
          return list;
     public static class ParallelResultObject implements ExternalizableLite {
          private MultiTagPubSearchCacheEntity[] entries;
          public ParallelResultObject() {}
          public ParallelResultObject(MultiTagPubSearchCacheEntity[] entries) {
               this.entries = entries;
          public List generateResultList() {
               ArrayList l = new ArrayList();
               for(int i=0;i<entries.length;i++) {
                    l.add(entries);
               return l;
          public void readExternal(DataInput input) throws IOException {
               int numEntries = ExternalizableHelper.readInt(input);
               if(numEntries >0) {
                    entries = new MultiTagPubSearchCacheEntity[numEntries];
                    for(int i=0;i<numEntries;i++) {
                         entries[i] = (MultiTagPubSearchCacheEntity)ExternalizableHelper.readObject(input);     
          public void writeExternal(DataOutput output) throws IOException {
               int numEntries = entries.length;
               if(numEntries >0) {
                    ExternalizableHelper.writeInt(output, numEntries);
                    for(int i=0;i<numEntries;i++) {
                         ExternalizableHelper.writeObject(output, entries[i]);     
     public static class SortingParallelAggregator implements ExternalizableLite, EntryAggregator {
          private String sortFlag;
          private String ascDescFlag;
          public SortingParallelAggregator() {
               super();
          public SortingParallelAggregator(String sortFlag, String ascDescFlag) {
               super();
               this.sortFlag = sortFlag;
               this.ascDescFlag = ascDescFlag;
          public Object aggregate(Set entries) {
               return sortEntries(entries, sortFlag, ascDescFlag);
          public void readExternal(DataInput input) throws IOException {
               sortFlag = ExternalizableHelper.readSafeUTF(input);
               ascDescFlag = ExternalizableHelper.readSafeUTF(input);
          public void writeExternal(DataOutput output) throws IOException {
               ExternalizableHelper.writeSafeUTF(output, sortFlag);
               ExternalizableHelper.writeSafeUTF(output, ascDescFlag);
          private ParallelResultObject sortEntries(Set entries, String sortFlag, String ascDescFlag) {
               ArrayList sortedList;
               ArrayList arrayList = new ArrayList(entries);     
               if ( sortFlag != null && !"".equals(sortFlag.trim()) ) {
     if ( Cache_Query_Constants.DATE_SORT_FLAG.equals(sortFlag.trim().toUpperCase()) ) {
                         sortedList = sortByDate(arrayList, ascDescFlag);
     } else {
     sortedList = arrayList;
     } else {
     sortedList = arrayList;
               return new ParallelResultObject(convertListToArray(sortedList));
          private ArrayList sortByDate(ArrayList arrayList, String ascDescFlag) {
               if("DESC".equals(ascDescFlag.trim().toUpperCase())) {
                    System.out.println("Start sort by DATE DESC");
                    Collections.sort(arrayList, new Comparator() {
                         public int compare(Object o1, Object o2) {
                              int rc = 0;
                              if((o1 instanceof MultiTagPubSearchCacheEntity) && (o2 instanceof MultiTagPubSearchCacheEntity))
                                   System.out.println("Sorting by MultiTagPubSearchCacheEntity ...");
                                   MultiTagPubSearchCacheEntity p1 = (MultiTagPubSearchCacheEntity) o1;
                                   MultiTagPubSearchCacheEntity p2 = (MultiTagPubSearchCacheEntity) o2;
                                   rc = p1.getPub_Date() - p2.getPub_Date();
                                   if ( rc == 0 ) {
                                        rc = p2.getTitle().compareTo(p1.getTitle());
                              return rc;
                    Collections.reverse(arrayList);
                    System.out.println("Done sort by DATE DESC");
               System.out.println("Size of sorted result : " + arrayList.size());
               Iterator iter = arrayList.iterator();
               while(iter.hasNext()) {
     MultiTagPubSearchCacheEntity e = (MultiTagPubSearchCacheEntity)iter.next();
     System.out.println("### Sorted Entries : " + e.toString());
               return arrayList;
          private MultiTagPubSearchCacheEntity[] convertListToArray(ArrayList sortedList) {
               MultiTagPubSearchCacheEntity[] entries = new MultiTagPubSearchCacheEntity[sortedList.size()];
               Iterator iter = sortedList.iterator();
               int idx = 0;
               while(iter.hasNext()) {
                    entries[idx] = (MultiTagPubSearchCacheEntity)iter.next();     
                    idx++;
               return entries;
==================================================
Thanks,
Bing

Answer 1

Hi, Gene
I'm getting another ClassCastException during the client call as below :
public class SortByServerFactory
        // sortFlag
        public static MultiTagPubSearchCacheEntity[] filterAndSortByServer(String cacheName, String sortFlag, String ascDescFlag, Filter filter)
                InvocableMap cache = CacheFactory.getCache(cacheName);
                return (MultiTagPubSearchCacheEntity[])cache.aggregate(filter, new SortByServerAggregator(sortFlag, ascDescFlag));
}2008-02-15 15:11:41.850 Oracle Coherence DC 3.3.1/389p1 <Info> (thread=main, member=n/a): Connected to 10.56.32.91:9098
Exception in thread "main" java.lang.ClassCastException
at com.docview.test.SortByServerFactory.filterAndSortByServer(SortByServerFactory.java:16)
at com.docview.test.TestRegSectorAnalystCacheQueryInvocationSVC.main(TestRegSectorAnalystCacheQueryInvocationSVC.java:83)
Attached please find my updated "SortByServerAggregator" class also :
The method "aggregateResults(Collection resultObjects)" within SortByServerAggregator class will return "MultiTagPubSearchCacheEntity[]"
Would you please help me to point out where is problem ?
Maybe I'm still not fully understand how ParallelAwareAggregator works, and what should be done for aggregate(Set entries), aggregateResults(Collection resultObjects) and getParallelAggregator() .
Many thanks for your help.
Bing
=========================================================
public class SortByServerAggregator implements ParallelAwareAggregator, ExternalizableLite {
     private String sortFlag;
     private String ascDescFlag;
     public SortByServerAggregator(String sortFlag, String ascDescFlag) {
          this.sortFlag = sortFlag;
          this.ascDescFlag = ascDescFlag;
     public SortByServerAggregator() {
          super();
     public Object aggregate(Set entries) {
          return new SortingParallelAggregator(sortFlag, ascDescFlag).aggregate(entries);
     public Object aggregateResults(Collection resultObjects) {
          return mergeMultipleResults(resultObjects);
     public EntryAggregator getParallelAggregator() {
          return new SortingParallelAggregator(sortFlag, ascDescFlag);
     public void readExternal(DataInput input) throws IOException {
          sortFlag = ExternalizableHelper.readSafeUTF(input);
          ascDescFlag = ExternalizableHelper.readSafeUTF(input);
     public void writeExternal(DataOutput output) throws IOException {
          ExternalizableHelper.writeSafeUTF(output, sortFlag);
          ExternalizableHelper.writeSafeUTF(output, ascDescFlag);
     private MultiTagPubSearchCacheEntity[] mergeMultipleResults(Collection resultObjects) {
          HashSet tmpSet = new HashSet();
          Iterator iter = resultObjects.iterator();
          while (iter.hasNext()) {
               ParallelResultObject result = (ParallelResultObject)iter.next();
               int numEntries = result.getNumEntries();
               if(numEntries > 0) {
                    MultiTagPubSearchCacheEntity[] entries = result.getEntries();
                    for(int i=0;i<numEntries;i++) {
                         tmpSet.add(entries);     
          return toEntityArray(tmpSet);
     private MultiTagPubSearchCacheEntity[] toEntityArray(HashSet s) {
          MultiTagPubSearchCacheEntity[] entries = new MultiTagPubSearchCacheEntity[s.size()];
          int idx = 0;
          Iterator iter = s.iterator();
          while (iter.hasNext()) {
               MultiTagPubSearchCacheEntity e = (MultiTagPubSearchCacheEntity)iter.next();
               entries[idx] = e;
               idx++;
          return entries;
     public static class ParallelResultObject implements ExternalizableLite {
          private MultiTagPubSearchCacheEntity[] entries;
          private int numEntries;
          public ParallelResultObject() {}
          public ParallelResultObject(MultiTagPubSearchCacheEntity[] entries, int numEntries) {
               this.entries = entries;
               this.numEntries = numEntries;
          public List generateResultList() {
               ArrayList l = new ArrayList();
               if(entries != null) {
                    for(int i=0;i<entries.length;i++) {
                         l.add(entries[i]);
               return l;
          public MultiTagPubSearchCacheEntity[] getEntries() {
               return entries;
          public int getNumEntries() {
               return numEntries;
          public void readExternal(DataInput input) throws IOException {
               int numEntries = ExternalizableHelper.readInt(input);
               if(numEntries >0) {
                    MultiTagPubSearchCacheEntity[] entries = new MultiTagPubSearchCacheEntity[numEntries];
                    for(int i=0;i<numEntries;i++) {
                         entries[i] = (MultiTagPubSearchCacheEntity)ExternalizableHelper.readObject(input);     
               this.entries = entries;
          public void writeExternal(DataOutput output) throws IOException {
               if(numEntries >0) {
                    ExternalizableHelper.writeInt(output, numEntries);
                    for(int i=0;i<numEntries;i++) {
                         ExternalizableHelper.writeObject(output, entries[i]);     
               } else {
                    ExternalizableHelper.writeInt(output, 0);
     public static class SortingParallelAggregator implements ExternalizableLite, EntryAggregator {
          private String sortFlag;
          private String ascDescFlag;
          public SortingParallelAggregator() {
               super();
          public SortingParallelAggregator(String sortFlag, String ascDescFlag) {
               super();
               this.sortFlag = sortFlag;
               this.ascDescFlag = ascDescFlag;
          public Object aggregate(Set entries) {
               return sortEntries(entries, sortFlag, ascDescFlag);
          public void readExternal(DataInput input) throws IOException {
               sortFlag = ExternalizableHelper.readSafeUTF(input);
               ascDescFlag = ExternalizableHelper.readSafeUTF(input);
          public void writeExternal(DataOutput output) throws IOException {
               ExternalizableHelper.writeSafeUTF(output, sortFlag);
               ExternalizableHelper.writeSafeUTF(output, ascDescFlag);
          private ParallelResultObject sortEntries(Set entries, String sortFlag, String ascDescFlag) {
               ArrayList sortedList;
               ArrayList arrayList = new ArrayList(entries);     
               if ( sortFlag != null && !"".equals(sortFlag.trim()) ) {
     if ( Cache_Query_Constants.DATE_SORT_FLAG.equals(sortFlag.trim().toUpperCase()) ) {
                         sortedList = sortByDate(arrayList, ascDescFlag);
     } else {
     sortedList = arrayList;
     } else {
     sortedList = arrayList;
               return new ParallelResultObject(convertListToArray(sortedList), sortedList.size());
          private ArrayList sortByDate(ArrayList arrayList, String ascDescFlag) {
               if("DESC".equals(ascDescFlag.trim().toUpperCase())) {
                    System.out.println("Start sort by DATE DESC");
                    Collections.sort(arrayList, new Comparator() {
                         public int compare(Object o1, Object o2) {
                              int rc = 0;
                              if((o1 instanceof MultiTagPubSearchCacheEntity) && (o2 instanceof MultiTagPubSearchCacheEntity))
                                   System.out.println("Sorting by MultiTagPubSearchCacheEntity ...");
                                   MultiTagPubSearchCacheEntity p1 = (MultiTagPubSearchCacheEntity) o1;
                                   MultiTagPubSearchCacheEntity p2 = (MultiTagPubSearchCacheEntity) o2;
                                   rc = p1.getPub_Date() - p2.getPub_Date();
                                   if ( rc == 0 ) {
                                        rc = p2.getTitle().compareTo(p1.getTitle());
                              return rc;
                    Collections.reverse(arrayList);
                    System.out.println("Done sort by DATE DESC");
               System.out.println("Size of sorted result : " + arrayList.size());
               Iterator iter = arrayList.iterator();
               while(iter.hasNext()) {
     InvocableMap.Entry entry = (InvocableMap.Entry)iter.next();
                    MultiTagPubSearchCacheEntity e = (MultiTagPubSearchCacheEntity)entry.getValue();     
     System.out.println("### Sorted Entries : " + e.toString());
               return arrayList;
          private MultiTagPubSearchCacheEntity[] convertListToArray(ArrayList sortedList) {
               MultiTagPubSearchCacheEntity[] entries = new MultiTagPubSearchCacheEntity[sortedList.size()];
               Iterator iter = sortedList.iterator();
               int idx = 0;
               while(iter.hasNext()) {
                    InvocableMap.Entry e = (InvocableMap.Entry)iter.next();
                    entries[idx] = (MultiTagPubSearchCacheEntity)e.getValue();
                    idx++;
               return entries;
=========================================================