Adding basic support for the subscription feature of the blockchain API and listening for transfer operations in transactions

src/main/java/de/bitsharesmunich/graphenej/AccountUpdateOperation.java

@@ -8,7 +8,7 @@ import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 
 /**
- * Class used to encapsulate operations related to the account_update_operation.
+ * Class used to encapsulate operations related to the ACCOUNT_UPDATE_OPERATION.
  */
 public class AccountUpdateOperation extends BaseOperation {
     public static final String KEY_ACCOUNT = "account";
@@ -34,7 +34,7 @@ public class AccountUpdateOperation extends BaseOperation {
      * @param fee The fee to pay. Can be null.
      */
     public AccountUpdateOperation(UserAccount account, Authority owner, Authority active, AccountOptions options, AssetAmount fee){
-        super(OperationType.account_update_operation);
+        super(OperationType.ACCOUNT_UPDATE_OPERATION);
         this.fee = fee;
         this.account = account;
         this.owner = new Optional<>(owner);

src/main/java/de/bitsharesmunich/graphenej/BlockData.java

@@ -12,7 +12,7 @@ public class BlockData implements ByteSerializable {
 
     private int refBlockNum;
     private long refBlockPrefix;
-    private long relativeExpiration;
+    private long expiration;
 
     /**
      * Block data constructor
@@ -22,22 +22,20 @@ public class BlockData implements ByteSerializable {
      *                        Recall that block IDs have 32 bits of block number followed by the
      *                        actual block hash, so this field should be set using the second 32 bits
      *                        in the block_id_type
-     * @param relative_expiration: This field specifies the number of block intervals after the
+     * @param relative_expiration: Expiration time specified as a POSIX or
-     *                           reference block until this transaction becomes invalid. If this field is
+     *                           <a href="https://en.wikipedia.org/wiki/Unix_time">Unix time</a>
-     *                           set to zero, the "ref_block_prefix" is interpreted as an absolute timestamp
-     *                           of the time the transaction becomes invalid.
      */
     public BlockData(int ref_block_num, long ref_block_prefix, long relative_expiration){
         this.refBlockNum = ref_block_num;
         this.refBlockPrefix = ref_block_prefix;
-        this.relativeExpiration = relative_expiration;
+        this.expiration = relative_expiration;
     }
 
     /**
      * Block data constructor that takes in raw blockchain information.
      * @param head_block_number: The last block number.
      * @param head_block_id: The last block apiId.
-     * @param relative_expiration: The relative expiration
+     * @param relative_expiration: The expiration time.
      */
     public BlockData(long head_block_number, String head_block_id, long relative_expiration){
         String hashData = head_block_id.substring(8, 16);
@@ -47,7 +45,7 @@ public class BlockData implements ByteSerializable {
         }
         this.setRefBlockNum(head_block_number);
         this.setRefBlockPrefix(head_block_id);
-        this.relativeExpiration = relative_expiration;
+        this.expiration = relative_expiration;
     }
 
     /**
@@ -97,12 +95,12 @@ public class BlockData implements ByteSerializable {
         return refBlockPrefix;
     }
 
-    public long getRelativeExpiration() {
+    public long getExpiration() {
-        return relativeExpiration;
+        return expiration;
     }
 
-    public void setRelativeExpiration(long relativeExpiration) {
+    public void setExpiration(long expiration) {
-        this.relativeExpiration = relativeExpiration;
+        this.expiration = expiration;
     }
 
 
@@ -120,7 +118,7 @@ public class BlockData implements ByteSerializable {
             }else if(i >= REF_BLOCK_NUM_BYTES && i < REF_BLOCK_NUM_BYTES + REF_BLOCK_PREFIX_BYTES){
                 result[i] = (byte) (this.refBlockPrefix >> 8 * (i - REF_BLOCK_NUM_BYTES));
             }else{
-                result[i] = (byte) (this.relativeExpiration >> 8 * (i - REF_BLOCK_NUM_BYTES + REF_BLOCK_PREFIX_BYTES));
+                result[i] = (byte) (this.expiration >> 8 * (i - REF_BLOCK_NUM_BYTES + REF_BLOCK_PREFIX_BYTES));
             }
         }
         return result;

src/main/java/de/bitsharesmunich/graphenej/GrapheneObject.java

@@ -8,6 +8,8 @@ package de.bitsharesmunich.graphenej;
  * Created by nelson on 11/8/16.
  */
 public class GrapheneObject {
+    public static final String KEY_ID = "id";
+
     public static final int PROTOCOL_SPACE = 1;
     public static final int IMPLEMENTATION_SPACE = 2;
 

src/main/java/de/bitsharesmunich/graphenej/Main.java

@@ -73,6 +73,7 @@ public class Main {
 //        test.testAssetSerialization();
 //        test.testGetMarketHistory();
 //        test.testGetAccountBalances();
-        test.testGetAssetHoldersCount();
+//        test.testGetAssetHoldersCount();
+        test.testSubscription(null);
     }
 }

src/main/java/de/bitsharesmunich/graphenej/OperationType.java

@@ -1,52 +1,55 @@
 package de.bitsharesmunich.graphenej;
 
 /**
+ * Enum type used to keep track of all the operation types and their corresponding ids.
+ *
+ * <a href="https://bitshares.org/doxygen/operations_8hpp_source.html">Source</a>
+ *
  * Created by nelson on 11/6/16.
  */
 public enum OperationType {
-    transfer_operation,
+    TRANSFER_OPERATION,
-    limit_order_create_operation,
+    LIMIT_ORDER_CREATE_OPERATION,
-    limit_order_cancel_operation,
+    LIMIT_ORDER_CANCEL_OPERATION,
-    call_order_update_operation,
+    CALL_ORDER_UPDATE_OPERATION,
-    fill_order_operation,           // VIRTUAL
+    FILL_ORDER_OPERATION,           // VIRTUAL
-    account_create_operation,
+    ACCOUNT_CREATE_OPERATION,
-    account_update_operation,
+    ACCOUNT_UPDATE_OPERATION,
-    account_whitelist_operation,
+    ACCOUNT_WHITELIST_OPERATION,
-    account_upgrade_operation,
+    ACCOUNT_UPGRADE_OPERATION,
-    account_transfer_operation,
+    ACCOUNT_TRANSFER_OPERATION,
-    asset_create_operation,
+    ASSET_CREATE_OPERATION,
-    asset_update_operation,
+    ASSET_UPDATE_OPERATION,
-    asset_update_bitasset_operation,
+    ASSET_UPDATE_BITASSET_OPERATION,
-    asset_update_feed_producers_operation,
+    ASSET_UPDATE_FEED_PRODUCERS_OPERATION,
-    asset_issue_operation,
+    ASSET_ISSUE_OPERATION,
-    asset_reserve_operation,
+    ASSET_RESERVE_OPERATION,
-    asset_fund_fee_pool_operation,
+    ASSET_FUND_FEE_POOL_OPERATION,
-    asset_settle_operation,
+    ASSET_SETTLE_OPERATION,
-    asset_global_settle_operation,
+    ASSET_GLOBAL_SETTLE_OPERATION,
-    asset_publish_feed_operation,
+    ASSET_PUBLISH_FEED_OPERATION,
-    witness_create_operation,
+    WITNESS_CREATE_OPERATION,
-    witness_update_operation,
+    WITNESS_UPDATE_OPERATION,
-    proposal_create_operation,
+    PROPOSAL_CREATE_OPERATION,
-    proposal_update_operation,
+    PROPOSAL_UPDATE_OPERATION,
-    proposal_delete_operation,
+    PROPOSAL_DELETE_OPERATION,
-    withdraw_permission_create_operation,
+    WITHDRAW_PERMISSION_CREATE_OPERATION,
-    withdraw_permission_update_operation,
+    WITHDRAW_PERMISSION_UPDATE_OPERATION,
-    withdraw_permission_claim_operation,
+    WITHDRAW_PERMISSION_CLAIM_OPERATION,
-    withdraw_permission_delete_operation,
+    WITHDRAW_PERMISSION_DELETE_OPERATION,
-    committee_member_create_operation,
+    COMMITTEE_MEMBER_CREATE_OPERATION,
-    committee_member_update_operation,
+    COMMITTEE_MEMBER_UPDATE_OPERATION,
-    committee_member_update_global_parameters_operation,
+    COMMITTEE_MEMBER_UPDATE_GLOBAL_PARAMETERS_OPERATION,
-    vesting_balance_create_operation,
+    VESTING_BALANCE_CREATE_OPERATION,
-    vesting_balance_withdraw_operation,
+    VESTING_BALANCE_WITHDRAW_OPERATION,
-    worker_create_operation,
+    WORKER_CREATE_OPERATION,
-    custom_operation,
+    CUSTOM_OPERATION,
-    assert_operation,
+    ASSERT_OPERATION,
-    balance_claim_operation,
+    BALANCE_CLAIM_OPERATION,
-    override_transfer_operation,
+    OVERRIDE_TRANSFER_OPERATION,
-    transfer_to_blind_operation,
+    TRANSFER_TO_BLIND_OPERATION,
-    blind_transfer_operation,
+    BLIND_TRANSFER_OPERATION,
-    transfer_from_blind_operation,
+    TRANSFER_FROM_BLIND_OPERATION,
-    asset_settle_cancel_operation,  // VIRTUAL
+    ASSET_SETTLE_CANCEL_OPERATION,  // VIRTUAL
-    asset_claim_fees_operation,
+    ASSET_CLAIM_FEES_OPERATION
-    fba_distribute_operation // VIRTUAL
 }

src/main/java/de/bitsharesmunich/graphenej/RPC.java

@@ -10,6 +10,7 @@ public class RPC {
     public static final String CALL_HISTORY = "history";
     public static final String CALL_DATABASE = "database";
     public static final String CALL_ASSET = "asset";
+    public static final String CALL_SET_SUBSCRIBE_CALLBACK = "set_subscribe_callback";
     public static final String CALL_GET_ACCOUNT_BY_NAME = "get_account_by_name";
     public static final String CALL_GET_ACCOUNTS = "get_accounts";
     public static final String CALL_GET_DYNAMIC_GLOBAL_PROPERTIES = "get_dynamic_global_properties";

src/main/java/de/bitsharesmunich/graphenej/Test.java

@@ -1,5 +1,6 @@
 package de.bitsharesmunich.graphenej;
 
+import de.bitsharesmunich.graphenej.interfaces.SubscriptionListener;
 import de.bitsharesmunich.graphenej.models.*;
 import de.bitsharesmunich.graphenej.objects.Memo;
 import com.google.common.primitives.UnsignedLong;
@@ -14,12 +15,10 @@ import de.bitsharesmunich.graphenej.test.NaiveSSLContext;
 import com.neovisionaries.ws.client.*;
 import de.bitsharesmunich.graphenej.api.*;
 import org.bitcoinj.core.*;
-import org.spongycastle.asn1.x509.Holder;
 import org.spongycastle.crypto.digests.RIPEMD160Digest;
 
 import javax.net.ssl.SSLContext;
 import java.io.*;
-import java.lang.reflect.Array;
 import java.lang.reflect.Type;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -592,7 +591,7 @@ public class Test {
             // Set the custom SSL context.
             factory.setSSLContext(context);
 
-            WebSocket mWebSocket = factory.createSocket(OPENLEDGER_WITNESS_URL);
+            WebSocket mWebSocket = factory.createSocket(AMAZON_WITNESS);
             mWebSocket.addListener(relativeAccountHistory);
             mWebSocket.connect();
         } catch (IOException e) {
@@ -1190,8 +1189,8 @@ public class Test {
             @Override
             public void onSuccess(WitnessResponse response) {
                 System.out.println("onSuccess");
-                List<HoldersCount> holdersCountList = (List<HoldersCount>) response.result;
+                List<AssetHolderCount> holdersCountList = (List<AssetHolderCount>) response.result;
-                for(HoldersCount holdersCount : holdersCountList){
+                for(AssetHolderCount holdersCount : holdersCountList){
                     System.out.println(String.format("Asset %s has %d holders", holdersCount.asset.getObjectId(), holdersCount.count));
                 }
             }
@@ -1221,4 +1220,60 @@ public class Test {
             System.out.println("IOException. Msg: " + e.getMessage());
         }
     }
+
+    public void testSubscription(WitnessResponseListener listener){
+        SSLContext context = null;
+
+        try {
+            context = NaiveSSLContext.getInstance("TLS");
+            WebSocketFactory factory = new WebSocketFactory();
+
+            // Set the custom SSL context.
+            factory.setSSLContext(context);
+
+            WebSocket mWebSocket = factory.createSocket(BLOCK_PAY_DE);
+
+            SubscriptionMessagesHub subscriptionHub = new SubscriptionMessagesHub("", "");
+            mWebSocket.addListener(subscriptionHub);
+            mWebSocket.connect();
+            subscriptionHub.addSubscriptionListener(new SubscriptionListener() {
+                @Override
+                public ObjectType getInterestObjectType() {
+                    return ObjectType.TRANSACTION_OBJECT;
+                }
+
+                @Override
+                public void onSubscriptionUpdate(SubscriptionResponse response) {
+                    try{
+                        List<Serializable> updatedObjects = (List<Serializable>) response.params.get(1);
+                        if(updatedObjects.size() > 0){
+                            for(Serializable update : updatedObjects){
+                                if(update instanceof BroadcastedTransaction){
+                                    Transaction t = ((BroadcastedTransaction) update).getTransaction();
+                                    if(t.getOperations().size() > 0){
+                                        for(BaseOperation op : t.getOperations()){
+                                            if(op instanceof TransferOperation){
+                                                System.out.println(String.format("Got transaction from: %s, to: %s", ((TransferOperation) op).getFrom().getObjectId(), ((TransferOperation) op).getTo().getObjectId()));
+                                            }
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }catch(Exception e){
+                        System.out.println("Exception. Msg: "+e.getMessage());
+                        for(StackTraceElement el : e.getStackTrace()){
+                            System.out.println(el.getFileName()+"#"+el.getMethodName()+":"+el.getLineNumber());
+                        }
+                    }
+                }
+            });
+        } catch (NoSuchAlgorithmException e) {
+            System.out.println("NoSuchAlgorithmException. Msg: " + e.getMessage());
+        } catch (WebSocketException e) {
+            System.out.println("WebSocketException. Msg: " + e.getMessage());
+        } catch (IOException e) {
+            System.out.println("IOException. Msg: " + e.getMessage());
+        }
+    }
 }

src/main/java/de/bitsharesmunich/graphenej/Transaction.java

@@ -1,12 +1,7 @@
 package de.bitsharesmunich.graphenej;
 
 import com.google.common.primitives.Bytes;
-import com.google.gson.GsonBuilder;
+import com.google.gson.*;
-import com.google.gson.JsonArray;
-import com.google.gson.JsonElement;
-import com.google.gson.JsonObject;
-import com.google.gson.JsonSerializationContext;
-import com.google.gson.JsonSerializer;
 import de.bitsharesmunich.graphenej.interfaces.ByteSerializable;
 import de.bitsharesmunich.graphenej.interfaces.JsonSerializable;
 
@@ -16,6 +11,7 @@ import org.bitcoinj.core.Sha256Hash;
 import org.bitcoinj.core.Utils;
 
 import java.lang.reflect.Type;
+import java.text.ParsePosition;
 import java.text.SimpleDateFormat;
 import java.util.ArrayList;
 import java.util.Date;
@@ -26,15 +22,18 @@ import java.util.TimeZone;
  * Class used to represent a generic Graphene transaction.
  */
 public class Transaction implements ByteSerializable, JsonSerializable {
-    private final String TAG = this.getClass().getName();
 
+    /* Default expiration time */
     public static final int DEFAULT_EXPIRATION_TIME = 30;
+
+    /* Constant field names used for serialization/deserialization purposes */
     public static final String KEY_EXPIRATION = "expiration";
     public static final String KEY_SIGNATURES = "signatures";
     public static final String KEY_OPERATIONS = "operations";
     public static final String KEY_EXTENSIONS = "extensions";
     public static final String KEY_REF_BLOCK_NUM = "ref_block_num";
     public static final String KEY_REF_BLOCK_PREFIX = "ref_block_prefix";
+    public static final String TIME_DATE_FORMAT = "yyyy-MM-dd'T'HH:mm:ss";
 
     private ECKey privateKey;
     private BlockData blockData;
@@ -64,6 +63,17 @@ public class Transaction implements ByteSerializable, JsonSerializable {
         this(DumpedPrivateKey.fromBase58(null, wif).getKey(), block_data, operation_list);
     }
 
+    /**
+     * Constructor used to build a Transaction object without a private key. This kind of object
+     * is used to represent a transaction data that we don't intend to serialize and sign.
+     * @param blockData: Block data instance, containing information about the location of this transaction in the blockchain.
+     * @param operationList: The list of operations included in this transaction.
+     */
+    public Transaction(BlockData blockData, List<BaseOperation> operationList){
+        this.blockData = blockData;
+        this.operations = operationList;
+    }
+
     /**
      * Updates the block data
      * @param blockData: New block data
@@ -87,6 +97,14 @@ public class Transaction implements ByteSerializable, JsonSerializable {
 
     public List<BaseOperation> getOperations(){ return this.operations; }
 
+    /**
+     * This method is used to query whether the instance has a private key.
+     * @return
+     */
+    public boolean hasPrivateKey(){
+        return this.privateKey != null;
+    }
+
     /**
      * Obtains a signature of this transaction. Please note that due to the current reliance on
      * bitcoinj to generate the signatures, and due to the fact that it uses deterministic
@@ -125,7 +143,7 @@ public class Transaction implements ByteSerializable, JsonSerializable {
             if(((sigData[0] & 0x80) != 0) || (sigData[0] == 0) ||
                     ((sigData[1] & 0x80) != 0) || ((sigData[32] & 0x80) != 0) ||
                     (sigData[32] == 0) || ((sigData[33] & 0x80)  != 0)){
-                this.blockData.setRelativeExpiration(this.blockData.getRelativeExpiration() + 1);
+                this.blockData.setExpiration(this.blockData.getExpiration() + 1);
             }else{
                 isGrapheneCanonical = true;
             }
@@ -186,8 +204,8 @@ public class Transaction implements ByteSerializable, JsonSerializable {
         byte[] signature = getGrapheneSignature();
 
         // Formatting expiration time
-        Date expirationTime = new Date(blockData.getRelativeExpiration() * 1000);
+        Date expirationTime = new Date(blockData.getExpiration() * 1000);
-        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
+        SimpleDateFormat dateFormat = new SimpleDateFormat(TIME_DATE_FORMAT);
         dateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
 
         // Adding expiration
@@ -216,11 +234,144 @@ public class Transaction implements ByteSerializable, JsonSerializable {
 
     }
 
-    class TransactionSerializer implements JsonSerializer<Transaction> {
+    /**
+     * Class used to encapsulate the procedure to be followed when converting a transaction from a
+     * java object to its JSON string format representation.
+     */
+    public static class TransactionSerializer implements JsonSerializer<Transaction> {
 
         @Override
         public JsonElement serialize(Transaction transaction, Type type, JsonSerializationContext jsonSerializationContext) {
             return transaction.toJsonObject();
         }
     }
+
+    /**
+     * Static inner class used to encapsulate the procedure to be followed when converting a transaction from its
+     * JSON string format representation into a java object instance.
+     */
+    public static class TransactionDeserializer implements JsonDeserializer<Transaction> {
+
+        @Override
+        public Transaction deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
+            JsonObject jsonObject = json.getAsJsonObject();
+
+            // Parsing block data information
+            int refBlockNum = jsonObject.get(KEY_REF_BLOCK_NUM).getAsInt();
+            long refBlockPrefix = jsonObject.get(KEY_REF_BLOCK_PREFIX).getAsLong();
+            String expiration = jsonObject.get(KEY_EXPIRATION).getAsString();
+            SimpleDateFormat dateFormat = new SimpleDateFormat(TIME_DATE_FORMAT);
+            dateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
+            Date expirationDate = dateFormat.parse(expiration, new ParsePosition(0));
+            BlockData blockData = new BlockData(refBlockNum, refBlockPrefix, expirationDate.getTime());
+
+            // Parsing operation list
+            BaseOperation operation = null;
+            ArrayList<BaseOperation> operationList = new ArrayList<>();
+            try {
+                for (JsonElement jsonOperation : jsonObject.get(KEY_OPERATIONS).getAsJsonArray()) {
+                    int operationId = jsonOperation.getAsJsonArray().get(0).getAsInt();
+                    if (operationId == OperationType.TRANSFER_OPERATION.ordinal()) {
+                        System.out.println("Transfer operation detected!");
+                        operation = context.deserialize(jsonOperation, TransferOperation.class);
+                    } else if (operationId == OperationType.LIMIT_ORDER_CREATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.LIMIT_ORDER_CANCEL_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.CALL_ORDER_UPDATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.FILL_ORDER_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ACCOUNT_CREATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ACCOUNT_UPDATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ACCOUNT_WHITELIST_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ACCOUNT_UPGRADE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ACCOUNT_TRANSFER_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ASSET_CREATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ASSET_UPDATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ASSET_UPDATE_BITASSET_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ASSET_UPDATE_FEED_PRODUCERS_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ASSET_ISSUE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ASSET_RESERVE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ASSET_FUND_FEE_POOL_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ASSET_SETTLE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ASSET_GLOBAL_SETTLE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ASSET_PUBLISH_FEED_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.WITNESS_CREATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.WITNESS_UPDATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.PROPOSAL_CREATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.PROPOSAL_UPDATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.PROPOSAL_DELETE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.WITHDRAW_PERMISSION_CREATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.WITHDRAW_PERMISSION_UPDATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.WITHDRAW_PERMISSION_CLAIM_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.WITHDRAW_PERMISSION_DELETE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.COMMITTEE_MEMBER_CREATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.COMMITTEE_MEMBER_UPDATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.COMMITTEE_MEMBER_UPDATE_GLOBAL_PARAMETERS_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.VESTING_BALANCE_CREATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.VESTING_BALANCE_WITHDRAW_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.WORKER_CREATE_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.CUSTOM_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ASSERT_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.BALANCE_CLAIM_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.OVERRIDE_TRANSFER_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.TRANSFER_TO_BLIND_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.BLIND_TRANSFER_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.TRANSFER_FROM_BLIND_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ASSET_SETTLE_CANCEL_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    } else if (operationId == OperationType.ASSET_CLAIM_FEES_OPERATION.ordinal()) {
+                        //TODO: Add operation deserialization support
+                    }
+                    if (operation != null) operationList.add(operation);
+                    operation = null;
+                }
+                return new Transaction(blockData, operationList);
+            }catch(Exception e){
+                System.out.println("Exception. Msg: "+e.getMessage());
+                for(StackTraceElement el : e.getStackTrace()){
+                    System.out.println(el.getFileName()+"#"+el.getMethodName()+":"+el.getLineNumber());
+                }
+            }
+            return new Transaction(blockData, operationList);
+        }
+    }
 }

src/main/java/de/bitsharesmunich/graphenej/TransferOperation.java

@@ -26,7 +26,7 @@ public class TransferOperation extends BaseOperation {
     private String[] extensions;
 
     public TransferOperation(UserAccount from, UserAccount to, AssetAmount transferAmount, AssetAmount fee){
-        super(OperationType.transfer_operation);
+        super(OperationType.TRANSFER_OPERATION);
         this.from = from;
         this.to = to;
         this.amount = transferAmount;
@@ -35,7 +35,7 @@ public class TransferOperation extends BaseOperation {
     }
 
     public TransferOperation(UserAccount from, UserAccount to, AssetAmount transferAmount){
-        super(OperationType.transfer_operation);
+        super(OperationType.TRANSFER_OPERATION);
         this.from = from;
         this.to = to;
         this.amount = transferAmount;
@@ -144,7 +144,7 @@ public class TransferOperation extends BaseOperation {
                 // This block is used just to check if we are in the first step of the deserialization
                 // when we are dealing with an array.
                 JsonArray serializedTransfer = json.getAsJsonArray();
-                if(serializedTransfer.get(0).getAsInt() != OperationType.transfer_operation.ordinal()){
+                if(serializedTransfer.get(0).getAsInt() != OperationType.TRANSFER_OPERATION.ordinal()){
                     // If the operation type does not correspond to a transfer operation, we return null
                     return null;
                 }else{

src/main/java/de/bitsharesmunich/graphenej/api/GetAllAssetHolders.java

@@ -63,10 +63,10 @@ public class GetAllAssetHolders extends BaseGrapheneHandler {
                 ApiCall apiCall = new ApiCall(assetApiId, RPC.CALL_GET_ALL_ASSET_HOLDERS, emptyParams, RPC.VERSION, currentId);
                 websocket.sendText(apiCall.toJsonString());
             } else if (baseResponse.id == GET_ALL_ASSET_HOLDERS_COUNT) {
-                Type AssetTokenHolders = new TypeToken<WitnessResponse<List<HoldersCount>>>(){}.getType();
+                Type AssetTokenHolders = new TypeToken<WitnessResponse<List<AssetHolderCount>>>(){}.getType();
                 GsonBuilder builder = new GsonBuilder();
-                builder.registerTypeAdapter(HoldersCount.class, new HoldersCount.HoldersCountDeserializer());
+                builder.registerTypeAdapter(AssetHolderCount.class, new AssetHolderCount.HoldersCountDeserializer());
-                WitnessResponse<List<HoldersCount>> witnessResponse = builder.create().fromJson(response, AssetTokenHolders);
+                WitnessResponse<List<AssetHolderCount>> witnessResponse = builder.create().fromJson(response, AssetTokenHolders);
                 mListener.onSuccess(witnessResponse);
                 websocket.disconnect();
             }else{

src/main/java/de/bitsharesmunich/graphenej/api/SubscriptionMessagesHub.java

@@ -0,0 +1,116 @@
+package de.bitsharesmunich.graphenej.api;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.reflect.TypeToken;
+import com.neovisionaries.ws.client.WebSocket;
+import com.neovisionaries.ws.client.WebSocketAdapter;
+import com.neovisionaries.ws.client.WebSocketException;
+import com.neovisionaries.ws.client.WebSocketFrame;
+import de.bitsharesmunich.graphenej.AssetAmount;
+import de.bitsharesmunich.graphenej.RPC;
+import de.bitsharesmunich.graphenej.Transaction;
+import de.bitsharesmunich.graphenej.TransferOperation;
+import de.bitsharesmunich.graphenej.interfaces.SubscriptionListener;
+import de.bitsharesmunich.graphenej.models.ApiCall;
+import de.bitsharesmunich.graphenej.models.BaseResponse;
+import de.bitsharesmunich.graphenej.models.SubscriptionResponse;
+import de.bitsharesmunich.graphenej.models.WitnessResponse;
+
+import java.io.Serializable;
+import java.lang.reflect.Type;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * A websocket adapter prepared to be used as a basic dispatch hub for subscription messages.
+ *
+ * Created by nelson on 1/26/17.
+ */
+public class SubscriptionMessagesHub extends WebSocketAdapter {
+    // Sequence of message ids
+    private final static int LOGIN_ID = 1;
+    private final static int GET_DATABASE_ID = 2;
+    private final static int SUBCRIPTION_REQUEST = 3;
+
+    // ID of subscription notifications
+    private final static int SUBCRIPTION_NOTIFICATION = 4;
+
+    private SubscriptionResponse.SubscriptionResponseDeserializer mSubscriptionDeserializer;
+    private Gson gson;
+    private String user;
+    private String password;
+    private int currentId = LOGIN_ID;
+    private int databaseApiId = -1;
+
+    public SubscriptionMessagesHub(String user, String password){
+        this.user = user;
+        this.password = password;
+        this.mSubscriptionDeserializer = new SubscriptionResponse.SubscriptionResponseDeserializer();
+        GsonBuilder builder = new GsonBuilder();
+        builder.registerTypeAdapter(SubscriptionResponse.class, mSubscriptionDeserializer);
+        builder.registerTypeAdapter(Transaction.class, new Transaction.TransactionDeserializer());
+        builder.registerTypeAdapter(TransferOperation.class, new TransferOperation.TransferDeserializer());
+        builder.registerTypeAdapter(AssetAmount.class, new AssetAmount.AssetAmountDeserializer());
+        this.gson = builder.create();
+    }
+
+    public void addSubscriptionListener(SubscriptionListener listener){
+        this.mSubscriptionDeserializer.addSubscriptionListener(listener);
+    }
+
+    public void removeSubscriptionListener(SubscriptionListener listener){
+        this.removeSubscriptionListener(listener);
+    }
+
+    @Override
+    public void onConnected(WebSocket websocket, Map<String, List<String>> headers) throws Exception {
+        ArrayList<Serializable> loginParams = new ArrayList<>();
+        loginParams.add(user);
+        loginParams.add(password);
+        ApiCall loginCall = new ApiCall(1, RPC.CALL_LOGIN, loginParams, RPC.VERSION, currentId);
+        websocket.sendText(loginCall.toJsonString());
+    }
+
+    @Override
+    public void onTextFrame(WebSocket websocket, WebSocketFrame frame) throws Exception {
+        String message = frame.getPayloadText();
+        System.out.println("<< "+message);
+        if(currentId == LOGIN_ID){
+            ArrayList<Serializable> emptyParams = new ArrayList<>();
+            ApiCall getDatabaseId = new ApiCall(1, RPC.CALL_DATABASE, emptyParams, RPC.VERSION, currentId);
+            websocket.sendText(getDatabaseId.toJsonString());
+        }else if(currentId == GET_DATABASE_ID){
+            Type ApiIdResponse = new TypeToken<WitnessResponse<Integer>>() {}.getType();
+            WitnessResponse<Integer> witnessResponse = gson.fromJson(message, ApiIdResponse);
+            databaseApiId = witnessResponse.result;
+
+            ArrayList<Serializable> subscriptionParams = new ArrayList<>();
+            subscriptionParams.add(String.format("%d", SUBCRIPTION_NOTIFICATION));
+            subscriptionParams.add(false);
+            ApiCall getDatabaseId = new ApiCall(databaseApiId, RPC.CALL_SET_SUBSCRIBE_CALLBACK, subscriptionParams, RPC.VERSION, currentId);
+            websocket.sendText(getDatabaseId.toJsonString());
+        }else if(currentId == SUBCRIPTION_REQUEST){
+            // Listeners are called from within the SubscriptionResponseDeserializer, so there's nothing to handle here.
+        }else{
+            SubscriptionResponse subscriptionResponse = gson.fromJson(message, SubscriptionResponse.class);
+        }
+        currentId++;
+    }
+
+    @Override
+    public void onFrameSent(WebSocket websocket, WebSocketFrame frame) throws Exception {
+        System.out.println(">> "+frame.getPayloadText());
+    }
+
+    @Override
+    public void onError(WebSocket websocket, WebSocketException cause) throws Exception {
+        super.onError(websocket, cause);
+    }
+
+    @Override
+    public void handleCallbackError(WebSocket websocket, Throwable cause) throws Exception {
+        super.handleCallbackError(websocket, cause);
+    }
+}

src/main/java/de/bitsharesmunich/graphenej/interfaces/SubscriptionListener.java

@@ -0,0 +1,30 @@
+package de.bitsharesmunich.graphenej.interfaces;
+
+import de.bitsharesmunich.graphenej.ObjectType;
+import de.bitsharesmunich.graphenej.models.SubscriptionResponse;
+
+/**
+ * Generic interface that must be implemented by any class that wants to be informed about a specific
+ * event notification.
+ *
+ * Created by nelson on 1/26/17.
+ */
+public interface SubscriptionListener {
+
+    /**
+     * Every subscription listener must implement a method that returns the type of object it is
+     * interested in.
+     * @return: Instance of the ObjectType enum class.
+     */
+    ObjectType getInterestObjectType();
+
+
+    /**
+     * Method called whenever there is an update that might be of interest for this listener.
+     * Note however that the objects returned inside the SubscriptionResponse are not guaranteed to be
+     * only of the object type requested by this class in the getInterestObjectType.
+     *
+     * @param response: SubscriptionResponse instance, which may or may not contain an object of interest.
+     */
+    void onSubscriptionUpdate(SubscriptionResponse response);
+}

src/main/java/de/bitsharesmunich/graphenej/models/ApiCall.java

@@ -88,6 +88,8 @@ public class ApiCall implements JsonSerializable {
                     }
                 }
                 methodParams.add(array);
+            }else if(this.params.get(i) instanceof Boolean){
+                methodParams.add((boolean) this.params.get(i));
             }else{
                 System.out.println("Skipping parameter of type: "+this.params.get(i).getClass());
             }

src/main/java/de/bitsharesmunich/graphenej/models/AssetHolderCount.java

@@ -8,19 +8,19 @@ import java.lang.reflect.Type;
 /**
  * Created by nelson on 1/25/17.
  */
-public class HoldersCount {
+public class AssetHolderCount {
     public static final String KEY_ASSET_ID = "asset_id";
     public static final String KEY_COUNT = "count";
 
     public Asset asset;
     public long count;
 
-    public static class HoldersCountDeserializer implements JsonDeserializer<HoldersCount> {
+    public static class HoldersCountDeserializer implements JsonDeserializer<AssetHolderCount> {
 
         @Override
-        public HoldersCount deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
+        public AssetHolderCount deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
             JsonObject jsonObject = json.getAsJsonObject();
-            HoldersCount holdersCount = new HoldersCount();
+            AssetHolderCount holdersCount = new AssetHolderCount();
             holdersCount.asset = new Asset(jsonObject.get(KEY_ASSET_ID).getAsString());
             holdersCount.count = jsonObject.get(KEY_COUNT).getAsLong();
             return holdersCount;

src/main/java/de/bitsharesmunich/graphenej/models/BroadcastedTransaction.java

@@ -0,0 +1,42 @@
+package de.bitsharesmunich.graphenej.models;
+
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonDeserializer;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonParseException;
+import de.bitsharesmunich.graphenej.GrapheneObject;
+import de.bitsharesmunich.graphenej.Transaction;
+
+import java.io.Serializable;
+import java.lang.reflect.Type;
+
+/**
+ * Created by nelson on 1/28/17.
+ */
+public class BroadcastedTransaction extends GrapheneObject implements Serializable {
+    public static final String KEY_TRX = "trx";
+    public static final String KEY_TRX_ID = "trx_id";
+
+    private Transaction trx;
+    private String trx_id;
+
+    public BroadcastedTransaction(String id){
+        super(id);
+    }
+
+    public void setTransaction(Transaction t){
+        this.trx = t;
+    }
+
+    public Transaction getTransaction() {
+        return trx;
+    }
+
+    public void setTransactionId(String id){
+        this.trx_id = id;
+    }
+
+    public String getTransactionId() {
+        return trx_id;
+    }
+}

src/main/java/de/bitsharesmunich/graphenej/models/SubscriptionResponse.java

@@ -9,13 +9,35 @@ import com.google.gson.JsonParseException;
 
 import java.io.Serializable;
 import java.lang.reflect.Type;
-import java.util.ArrayList;
+import java.util.*;
-import java.util.List;
 
-import de.bitsharesmunich.graphenej.GrapheneObject;
+import de.bitsharesmunich.graphenej.*;
-import de.bitsharesmunich.graphenej.ObjectType;
+import de.bitsharesmunich.graphenej.interfaces.SubscriptionListener;
 
 /**
+ * Class that represents a generic subscription response.
+ * The template for every subscription response is the following:
+ *
+ *  {
+ *    "method": "notice"
+ *    "params": [
+ *      SUBSCRIPTION_ID,
+ *        [[
+ *          { "id": "2.1.0", ...  },
+ *          { "id": ...  },
+ *          { "id": ...  },
+ *          { "id": ...  }
+ *        ]]
+ *    ],
+ *  }
+ *
+ * As of 1/2017, the witness API returns all sort of events, not just the ones we're interested in once we
+ * make a call to the 'set_subscribe_callback', regardless of whether the 'clear_filter' parameter is set to
+ * true or false.
+ *
+ * To minimize CPU usage, we introduce a scheme of selective parsing, implemented by the static inner class
+ * SubscriptionResponseDeserializer.
+ *
  * Created by nelson on 1/12/17.
  */
 public class SubscriptionResponse {
@@ -27,7 +49,49 @@ public class SubscriptionResponse {
     public String method;
     public List<Serializable> params;
 
+    /**
+     * Deserializer class that is used to parse and deserialize subscription responses in a partial way,
+     * depending on the amount of SubscriptionListeners we might have registered.
+     *
+     * The rationale behind these architecture is to avoid wasting computational resources parsing unneeded
+     * objects that might come once the are subscribed to the witness notifications.
+     */
     public static class SubscriptionResponseDeserializer implements JsonDeserializer<SubscriptionResponse> {
+        private HashMap<ObjectType, Integer> listenerTypeCount;
+        private LinkedList<SubscriptionListener> mListeners;
+
+        /**
+         * Constructor that will just create a list of SubscriptionListeners and
+         * a map of ObjectType to integer in order to keep track of how many listeners
+         * to each type of object we have.
+         */
+        public SubscriptionResponseDeserializer(){
+            mListeners = new LinkedList<>();
+            listenerTypeCount = new HashMap<>();
+        }
+
+        public void addSubscriptionListener(SubscriptionListener subscriptionListener){
+            int currentCount = 0;
+            if(listenerTypeCount.containsKey(subscriptionListener.getInterestObjectType())){
+                currentCount = listenerTypeCount.get(subscriptionListener.getInterestObjectType());
+            }
+            this.listenerTypeCount.put(subscriptionListener.getInterestObjectType(), currentCount + 1);
+            this.mListeners.add(subscriptionListener);
+        }
+
+        public List<SubscriptionListener> getSubscriptionListeners(){
+            return this.mListeners;
+        }
+
+        public void removeSubscriptionListener(SubscriptionListener subscriptionListener){
+            int currentCount = listenerTypeCount.get(subscriptionListener.getInterestObjectType());
+            if(currentCount != 0){
+                this.listenerTypeCount.put(subscriptionListener.getInterestObjectType(), currentCount);
+            }else{
+                System.out.println("Trying to remove subscription listener, but none is registered!");
+            }
+            this.mListeners.remove(subscriptionListener);
+        }
 
         @Override
         public SubscriptionResponse deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
@@ -44,7 +108,18 @@ public class SubscriptionResponse {
             JsonArray subArray = paramsArray.get(1).getAsJsonArray().get(0).getAsJsonArray();
             for(JsonElement object : subArray){
                 if(object.isJsonObject()){
+
                     GrapheneObject grapheneObject = new GrapheneObject(object.getAsJsonObject().get(KEY_ID).getAsString());
+                    int listenerTypeCount = 0;
+                    if(this.listenerTypeCount.containsKey(grapheneObject.getObjectType())){
+                        listenerTypeCount = this.listenerTypeCount.get(grapheneObject.getObjectType());
+                    }
+                    /*
+                     * Here's where we apply the selective deserialization logic, meaning we only completely deserialize
+                     * an object contained in a notification if there is at least one registered listener interested in
+                     * objects of that type.
+                     */
+                    if(listenerTypeCount > 0){
                         JsonObject jsonObject = object.getAsJsonObject();
                         if(grapheneObject.getObjectType() == ObjectType.ACCOUNT_BALANCE_OBJECT){
                             AccountBalanceUpdate balanceObject = new AccountBalanceUpdate(grapheneObject.getObjectId());
@@ -59,11 +134,22 @@ public class SubscriptionResponse {
                             dynamicGlobal.time = jsonObject.get(DynamicGlobalProperties.KEY_TIME).getAsString();
                             //TODO: Deserialize all other attributes
                             secondArgument.add(dynamicGlobal);
+                        }else if(grapheneObject.getObjectType() == ObjectType.TRANSACTION_OBJECT){
+                            BroadcastedTransaction broadcastedTransaction = new BroadcastedTransaction(grapheneObject.getObjectId());
+                            broadcastedTransaction.setTransaction(context.deserialize(jsonObject.get(BroadcastedTransaction.KEY_TRX), Transaction.class));
+                            broadcastedTransaction.setTransactionId(jsonObject.get(BroadcastedTransaction.KEY_TRX_ID).getAsString());
+                            secondArgument.add(broadcastedTransaction);
+                        }else{
+                            //TODO: Add support for other types of objects
+                        }
                     }
                 }else{
                     secondArgument.add(object.getAsString());
                 }
             }
+            for(SubscriptionListener listener : mListeners){
+                listener.onSubscriptionUpdate(response);
+            }
             return response;
         }
     }