The current mechanism for serializing content will not work for complex content types.

Now we need to add methods to KadContent objects to provide the byte[] format of their content and to re-read the byte format of their content.

src/kademlia/dht/DHT.java

@@ -84,12 +84,18 @@ public class DHT
         /* Keep track of this content in the entries manager */
         try
         {
-            StorageEntry sEntry = this.entriesManager.put(content);
+            StorageEntryMetadata sEntry = this.entriesManager.put(content);
 
             /* Now we store the content locally in a file */
             String contentStorageFolder = this.getContentStorageFolderName(content.getKey());
-            DataOutputStream dout = new DataOutputStream(new FileOutputStream(contentStorageFolder + File.separator + sEntry.hashCode() + ".kct"));
-            getContentSerializer().write(content, dout);
+
+            try (FileOutputStream fout = new FileOutputStream(contentStorageFolder + File.separator + sEntry.hashCode() + ".kct");
+                    DataOutputStream dout = new DataOutputStream(fout))
+            {
+                byte[] data = content.toBytes();
+                dout.writeInt(data.length);
+                dout.write(data);
+            }
         }
         catch (ContentExistException e)
         {
@@ -105,11 +111,15 @@ public class DHT
      *
      * @return A KadContent object
      */
-    private KadContent retrieve(NodeId key, int hashCode) throws FileNotFoundException, IOException, ClassNotFoundException
+    private byte[] retrieve(NodeId key, int hashCode) throws FileNotFoundException, IOException, ClassNotFoundException
     {
         String folder = this.getContentStorageFolderName(key);
-        DataInputStream in = new DataInputStream(new FileInputStream(folder + File.separator + hashCode + ".kct"));
-        return getContentSerializer().read(in);
+        DataInputStream din = new DataInputStream(new FileInputStream(folder + File.separator + hashCode + ".kct"));
+        int length = din.readInt();
+
+        byte[] data = new byte[length];
+        din.read(data);
+        return data;
     }
 
     /**
@@ -133,7 +143,7 @@ public class DHT
      *
      * @throws java.io.IOException
      */
-    public KadContent get(StorageEntry entry) throws IOException, NoSuchElementException
+    public byte[] get(StorageEntryMetadata entry) throws IOException, NoSuchElementException
     {
         try
         {
@@ -162,12 +172,12 @@ public class DHT
      *
      * @throws java.io.IOException
      */
-    public KadContent get(GetParameter param) throws NoSuchElementException, IOException
+    public byte[] get(GetParameter param) throws NoSuchElementException, IOException
     {
         /* Load a KadContent if any exist for the given criteria */
         try
         {
-            StorageEntry e = this.entriesManager.get(param);
+            StorageEntryMetadata e = this.entriesManager.get(param);
             return this.retrieve(e.getKey(), e.hashCode());
         }
         catch (FileNotFoundException e)
@@ -193,10 +203,10 @@ public class DHT
      */
     public void remove(KadContent content) throws ContentNotFoundException
     {
-        this.remove(new StorageEntry(content));
+        this.remove(new StorageEntryMetadata(content));
     }
 
-    public void remove(StorageEntry entry) throws ContentNotFoundException
+    public void remove(StorageEntryMetadata entry) throws ContentNotFoundException
     {
         String folder = this.getContentStorageFolderName(entry.getKey());
         File file = new File(folder + File.separator + entry.hashCode() + ".kct");
@@ -242,7 +252,7 @@ public class DHT
     /**
      * @return A List of all StorageEntries for this node
      */
-    public List<StorageEntry> getStorageEntries()
+    public List<StorageEntryMetadata> getStorageEntries()
     {
         return entriesManager.getAllEntries();
     }
@@ -253,9 +263,9 @@ public class DHT
      *
      * @param ientries The entries to add
      */
-    public void putStorageEntries(List<StorageEntry> ientries)
+    public void putStorageEntries(List<StorageEntryMetadata> ientries)
     {
-        for (StorageEntry e : ientries)
+        for (StorageEntryMetadata e : ientries)
         {
             try
             {

src/kademlia/dht/KadContent.java

@@ -41,4 +41,14 @@ public interface KadContent
      * @return The ID of the owner of this content
      */
     public String getOwnerId();
+
+    public default byte[] toBytes()
+    {
+        return new byte[2];
+    }
+
+    public default void fromBytes(byte[] data)
+    {
+
+    }
 }

src/kademlia/dht/StorageEntry.java

@@ -1,117 +1,23 @@
 package kademlia.dht;
 
-import java.util.Objects;
-import kademlia.core.GetParameter;
-import kademlia.node.NodeId;
-
 /**
- * Keeps track of data for a Content stored in the DHT
- * Used by the StorageEntryManager class
+ * A StorageEntry class that is used to store a content on the DHT
  *
  * @author Joshua Kissoon
- * @since 20140226
+ * @since 20140402
  */
 public class StorageEntry
 {
-
-    private final NodeId key;
-    private final String ownerId;
-    private final String type;
-    private final int contentHash;
-    private final long lastUpdated;
-
+    private byte[] content;
+    private StorageEntryMetadata metadata;
+    
     public StorageEntry(KadContent content)
     {
-        this.key = content.getKey();
-        this.ownerId = content.getOwnerId();
-        this.type = content.getType();
-        this.contentHash = content.hashCode();
-        this.lastUpdated = content.getLastUpdatedTimestamp();
-    }
-
-    public NodeId getKey()
-    {
-        return this.key;
-    }
-
-    public String getOwnerId()
-    {
-        return this.ownerId;
-    }
-
-    public String getType()
-    {
-        return this.type;
-    }
-
-    public int getContentHash()
-    {
-        return this.contentHash;
-    }
-
-    /**
-     * When a node is looking for content, he sends the search criteria in a GetParameter object
-     * Here we take this GetParameter object and check if this StorageEntry satisfies the given parameters
-     *
-     * @param params
-     *
-     * @return boolean Whether this content satisfies the parameters
-     */
-    public boolean satisfiesParameters(GetParameter params)
-    {
-        /* Check that owner id matches */
-        if ((params.getOwnerId() != null) && (!params.getOwnerId().equals(this.ownerId)))
-        {
-            return false;
-        }
         
-        /* Check that type matches */
-        if ((params.getType() != null) && (!params.getType().equals(this.type)))
-        {
-            return false;
-        }
-
-        /* Check that key matches */
-        return (params.getKey() != null) && (params.getKey().equals(this.key));
     }
-
-    @Override
-    public boolean equals(Object o)
+    
+    public StorageEntry(KadContent content, StorageEntryMetadata metadata)
     {
-        if (o instanceof StorageEntry)
-        {
-            return this.hashCode() == o.hashCode();
-        }
-
-        return false;
-    }
-
-    @Override
-    public int hashCode()
-    {
-        int hash = 3;
-        hash = 23 * hash + Objects.hashCode(this.key);
-        hash = 23 * hash + Objects.hashCode(this.ownerId);
-        hash = 23 * hash + Objects.hashCode(this.type);
-        return hash;
-    }
-
-    @Override
-    public String toString()
-    {
-        StringBuilder sb = new StringBuilder("[StorageEntry: ");
-
-        sb.append("{Key: ");
-        sb.append(this.key);
-        sb.append("} ");
-        sb.append("{Owner: ");
-        sb.append(this.ownerId);
-        sb.append("} ");
-        sb.append("{Type: ");
-        sb.append(this.type);
-        sb.append("} ");
-        sb.append("]");
-
-        return sb.toString();
+        this.content = content.g
     }
 }

src/kademlia/dht/StorageEntryManager.java

@@ -21,7 +21,7 @@ import kademlia.node.NodeId;
 class StorageEntryManager
 {
 
-    private final Map<NodeId, List<StorageEntry>> entries;
+    private final Map<NodeId, List<StorageEntryMetadata>> entries;
 
     
     {
@@ -33,9 +33,9 @@ class StorageEntryManager
      *
      * @param content The content to store a reference to
      */
-    public StorageEntry put(KadContent content) throws ContentExistException
+    public StorageEntryMetadata put(KadContent content) throws ContentExistException
     {
-        return this.put(new StorageEntry(content));
+        return this.put(new StorageEntryMetadata(content));
     }
 
     /**
@@ -43,11 +43,11 @@ class StorageEntryManager
      *
      * @param entry The StorageEntry to store
      */
-    public StorageEntry put(StorageEntry entry) throws ContentExistException
+    public StorageEntryMetadata put(StorageEntryMetadata entry) throws ContentExistException
     {
         if (!this.entries.containsKey(entry.getKey()))
         {
-            this.entries.put(entry.getKey(), new ArrayList<StorageEntry>());
+            this.entries.put(entry.getKey(), new ArrayList<>());
         }
 
         /* If this entry doesn't already exist, then we add it */
@@ -78,7 +78,7 @@ class StorageEntryManager
         {
             System.out.println("Does contain the key");
             /* Content with this key exist, check if any match the rest of the search criteria */
-            for (StorageEntry e : this.entries.get(param.getKey()))
+            for (StorageEntryMetadata e : this.entries.get(param.getKey()))
             {
                 /* If any entry satisfies the given parameters, return true */
                 if (e.satisfiesParameters(param))
@@ -100,13 +100,13 @@ class StorageEntryManager
      */
     public boolean contains(KadContent content)
     {
-        return this.contains(new StorageEntry(content));
+        return this.contains(new StorageEntryMetadata(content));
     }
 
     /**
      * Check if a StorageEntry exist on this DHT
      */
-    private boolean contains(StorageEntry entry)
+    private boolean contains(StorageEntryMetadata entry)
     {
         if (this.entries.containsKey(entry.getKey()))
         {
@@ -125,12 +125,12 @@ class StorageEntryManager
      *
      * @return List of content for the specific search parameters
      */
-    public StorageEntry get(GetParameter param) throws NoSuchElementException
+    public StorageEntryMetadata get(GetParameter param) throws NoSuchElementException
     {
         if (this.entries.containsKey(param.getKey()))
         {
             /* Content with this key exist, check if any match the rest of the search criteria */
-            for (StorageEntry e : this.entries.get(param.getKey()))
+            for (StorageEntryMetadata e : this.entries.get(param.getKey()))
             {
                 /* If any entry satisfies the given parameters, return true */
                 if (e.satisfiesParameters(param))
@@ -151,11 +151,11 @@ class StorageEntryManager
     /**
      * @return A list of all storage entries
      */
-    public List<StorageEntry> getAllEntries()
+    public List<StorageEntryMetadata> getAllEntries()
     {
-        List<StorageEntry> entriesRet = new ArrayList<>();
+        List<StorageEntryMetadata> entriesRet = new ArrayList<>();
 
-        for (List<StorageEntry> entrySet : this.entries.values())
+        for (List<StorageEntryMetadata> entrySet : this.entries.values())
         {
             if (entrySet.size() > 0)
             {
@@ -168,10 +168,10 @@ class StorageEntryManager
 
     public void remove(KadContent content) throws ContentNotFoundException
     {
-        this.remove(new StorageEntry(content));
+        this.remove(new StorageEntryMetadata(content));
     }
 
-    public void remove(StorageEntry entry) throws ContentNotFoundException
+    public void remove(StorageEntryMetadata entry) throws ContentNotFoundException
     {
         if (contains(entry))
         {
@@ -187,14 +187,14 @@ class StorageEntryManager
     public String toString()
     {
         StringBuilder sb = new StringBuilder("Stored Content: \n");
-        for (List<StorageEntry> es : this.entries.values())
+        for (List<StorageEntryMetadata> es : this.entries.values())
         {
             if (entries.size() < 1)
             {
                 continue;
             }
 
-            for (StorageEntry e : es)
+            for (StorageEntryMetadata e : es)
             {
                 sb.append(e);
                 sb.append("\n");

src/kademlia/dht/StorageEntryMetadata.java

@@ -0,0 +1,117 @@
+package kademlia.dht;
+
+import java.util.Objects;
+import kademlia.core.GetParameter;
+import kademlia.node.NodeId;
+
+/**
+ * Keeps track of data for a Content stored in the DHT
+ * Used by the StorageEntryManager class
+ *
+ * @author Joshua Kissoon
+ * @since 20140226
+ */
+public class StorageEntryMetadata
+{
+
+    private final NodeId key;
+    private final String ownerId;
+    private final String type;
+    private final int contentHash;
+    private final long lastUpdated;
+
+    public StorageEntryMetadata(KadContent content)
+    {
+        this.key = content.getKey();
+        this.ownerId = content.getOwnerId();
+        this.type = content.getType();
+        this.contentHash = content.hashCode();
+        this.lastUpdated = content.getLastUpdatedTimestamp();
+    }
+
+    public NodeId getKey()
+    {
+        return this.key;
+    }
+
+    public String getOwnerId()
+    {
+        return this.ownerId;
+    }
+
+    public String getType()
+    {
+        return this.type;
+    }
+
+    public int getContentHash()
+    {
+        return this.contentHash;
+    }
+
+    /**
+     * When a node is looking for content, he sends the search criteria in a GetParameter object
+     * Here we take this GetParameter object and check if this StorageEntry satisfies the given parameters
+     *
+     * @param params
+     *
+     * @return boolean Whether this content satisfies the parameters
+     */
+    public boolean satisfiesParameters(GetParameter params)
+    {
+        /* Check that owner id matches */
+        if ((params.getOwnerId() != null) && (!params.getOwnerId().equals(this.ownerId)))
+        {
+            return false;
+        }
+
+        /* Check that type matches */
+        if ((params.getType() != null) && (!params.getType().equals(this.type)))
+        {
+            return false;
+        }
+
+        /* Check that key matches */
+        return (params.getKey() != null) && (params.getKey().equals(this.key));
+    }
+
+    @Override
+    public boolean equals(Object o)
+    {
+        if (o instanceof StorageEntryMetadata)
+        {
+            return this.hashCode() == o.hashCode();
+        }
+
+        return false;
+    }
+
+    @Override
+    public int hashCode()
+    {
+        int hash = 3;
+        hash = 23 * hash + Objects.hashCode(this.key);
+        hash = 23 * hash + Objects.hashCode(this.ownerId);
+        hash = 23 * hash + Objects.hashCode(this.type);
+        return hash;
+    }
+
+    @Override
+    public String toString()
+    {
+        StringBuilder sb = new StringBuilder("[StorageEntry: ");
+
+        sb.append("{Key: ");
+        sb.append(this.key);
+        sb.append("} ");
+        sb.append("{Owner: ");
+        sb.append(this.ownerId);
+        sb.append("} ");
+        sb.append("{Type: ");
+        sb.append(this.type);
+        sb.append("} ");
+        sb.append("]");
+
+        return sb.toString();
+    }
+}

src/kademlia/message/ContentMessage.java

@@ -18,7 +18,7 @@ public class ContentMessage implements Message
 
     public static final byte CODE = 0x04;
 
-    private KadContent content;
+    private byte[] content;
     private Node origin;
 
     /**
@@ -26,7 +26,7 @@ public class ContentMessage implements Message
      * @param content The content to be stored
      *
      */
-    public ContentMessage(Node origin, KadContent content)
+    public ContentMessage(Node origin, byte[] content)
     {
         this.content = content;
         this.origin = origin;
@@ -43,7 +43,8 @@ public class ContentMessage implements Message
         this.origin.toStream(out);
 
         /* Serialize the KadContent, then send it to the stream */
-        new JsonSerializer<KadContent>().write(content, out);
+        out.writeInt(content.length);
+        out.write(content);
     }
 
     @Override
@@ -51,14 +52,9 @@ public class ContentMessage implements Message
     {
         this.origin = new Node(in);
 
-        try
-        {
-            this.content = new JsonSerializer<KadContent>().read(in);
-        }
-        catch (ClassNotFoundException e)
-        {
-            e.printStackTrace();
-        }
+        final int length = in.readInt();
+        this.content = new byte[length];
+        in.read(content);
     }
 
     public Node getOrigin()
@@ -66,7 +62,7 @@ public class ContentMessage implements Message
         return this.origin;
     }
 
-    public KadContent getContent()
+    public byte[] getContent()
     {
         return this.content;
     }

src/kademlia/operation/ContentRefreshOperation.java

@@ -6,7 +6,7 @@ import kademlia.core.DefaultConfiguration;
 import kademlia.core.KadConfiguration;
 import kademlia.core.KadServer;
 import kademlia.dht.DHT;
-import kademlia.dht.StorageEntry;
+import kademlia.dht.StorageEntryMetadata;
 import kademlia.exceptions.ContentNotFoundException;
 import kademlia.message.Message;
 import kademlia.message.StoreContentMessage;
@@ -46,10 +46,10 @@ public class ContentRefreshOperation implements Operation
     public void execute() throws IOException
     {
         /* Get a list of all storage entries for content */
-        List<StorageEntry> entries = this.dht.getStorageEntries();
+        List<StorageEntryMetadata> entries = this.dht.getStorageEntries();
 
         /* For each storage entry, distribute it */
-        for (StorageEntry e : entries)
+        for (StorageEntryMetadata e : entries)
         {
             /**
              * @todo - Paper improvement 1 -

src/kademlia/serializer/JsonDHTSerializer.java

@@ -12,7 +12,7 @@ import java.io.OutputStreamWriter;
 import java.lang.reflect.Type;
 import java.util.List;
 import kademlia.dht.DHT;
-import kademlia.dht.StorageEntry;
+import kademlia.dht.StorageEntryMetadata;
 
 /**
  * A KadSerializer that serializes DHT to JSON format
@@ -48,7 +48,7 @@ public class JsonDHTSerializer implements KadSerializer<DHT>
     {
         gson = new Gson();
 
-        storageEntriesCollectionType = new TypeToken<List<StorageEntry>>()
+        storageEntriesCollectionType = new TypeToken<List<StorageEntryMetadata>>()
         {
         }.getType();
     }
@@ -84,7 +84,7 @@ public class JsonDHTSerializer implements KadSerializer<DHT>
             dht.initialize();
 
             /* Now get the entries and add them back to the DHT */
-            List<StorageEntry> entries = gson.fromJson(reader, this.storageEntriesCollectionType);
+            List<StorageEntryMetadata> entries = gson.fromJson(reader, this.storageEntriesCollectionType);
             dht.putStorageEntries(entries);
 
             reader.endArray();

src/kademlia/serializer/JsonSerializer.java

@@ -43,7 +43,6 @@ public class JsonSerializer<T> implements KadSerializer<T>
 
             writer.endArray();
         }
-
     }
 
     @Override

src/kademlia/tests/DHTContentImpl.java

@@ -42,7 +42,7 @@ public class DHTContentImpl implements KadContent
         this.data = newData;
     }
 
-    public String getData()
+    public String toBytes()
     {
         return this.data;
     }