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From: ecapriolo@apache.org
To: commits@gossip.incubator.apache.org
Date: Wed, 02 Aug 2017 01:58:55 -0000
Message-Id: <06bf0695ef8c4f16a5720b82277848c7@git.apache.org>
Subject: [1/2] incubator-gossip git commit: GOSSIP-89 - Refactor gossip
 examples; common code in base class.
archived-at: Wed, 02 Aug 2017 01:59:11 -0000

Repository: incubator-gossip
Updated Branches:
  refs/heads/master 94da0bb64 -> 95e166770


GOSSIP-89 - Refactor gossip examples; common code in base class.


Project: http://git-wip-us.apache.org/repos/asf/incubator-gossip/repo
Commit: http://git-wip-us.apache.org/repos/asf/incubator-gossip/commit/1c673c85
Tree: http://git-wip-us.apache.org/repos/asf/incubator-gossip/tree/1c673c85
Diff: http://git-wip-us.apache.org/repos/asf/incubator-gossip/diff/1c673c85

Branch: refs/heads/master
Commit: 1c673c859719e99f24ecc3ffed882667a14c44fd
Parents: 95cce48
Author: Terry Weymouth <weymouth@umich.edu>
Authored: Sat Jul 1 10:19:24 2017 -0400
Committer: Terry Weymouth <weymouth@umich.edu>
Committed: Tue Jul 18 07:12:28 2017 -0500

----------------------------------------------------------------------
 .../apache/gossip/examples/ExampleCommon.java   |  50 ------
 .../gossip/examples/RunStandardExamples.java    | 105 ++++++++++++
 .../examples/StandAloneDatacenterAndRack.java   |  37 +++--
 .../gossip/examples/StandAloneExampleBase.java  | 162 +++++++++++++++++++
 .../apache/gossip/examples/StandAloneNode.java  |  49 +++---
 .../examples/StandAloneNodeCrdtOrSet.java       | 128 ++++++++-------
 .../gossip/examples/StandAlonePNCounter.java    | 130 ++++-----------
 7 files changed, 402 insertions(+), 259 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/incubator-gossip/blob/1c673c85/gossip-examples/src/main/java/org/apache/gossip/examples/ExampleCommon.java
----------------------------------------------------------------------
diff --git a/gossip-examples/src/main/java/org/apache/gossip/examples/ExampleCommon.java b/gossip-examples/src/main/java/org/apache/gossip/examples/ExampleCommon.java
deleted file mode 100644
index 279bff1..0000000
--- a/gossip-examples/src/main/java/org/apache/gossip/examples/ExampleCommon.java
+++ /dev/null
@@ -1,50 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.apache.gossip.examples;
-
-public class ExampleCommon {
-
-  private boolean clearTerminalScreen = true;
-
-  /*
-   * Look for -s in args. If there, suppress terminal-clear on write results Shift args for
-   * positional args, if necessary
-   */
-  public String[] checkArgsForClearFlag(String[] args) {
-    int pos = 0;
-    for (int i = 0; i < args.length; i++) {
-      if (args[i].equals("-s")) {
-        clearTerminalScreen = false;
-      } else {
-        // in the case of the -s flag, shift args 
-        // down by one slot; this will end up with
-        // a duplicate entry in the last position of args,
-        // but this is ok, because it will be ignored
-        args[pos++] = args[i];
-      }
-    }
-    return args;
-  }
-
-  public void optionallyClearTerminal() {
-    if (clearTerminalScreen) {
-      System.out.print("\033[H\033[2J");
-      System.out.flush();
-    }
-  }
-}

http://git-wip-us.apache.org/repos/asf/incubator-gossip/blob/1c673c85/gossip-examples/src/main/java/org/apache/gossip/examples/RunStandardExamples.java
----------------------------------------------------------------------
diff --git a/gossip-examples/src/main/java/org/apache/gossip/examples/RunStandardExamples.java b/gossip-examples/src/main/java/org/apache/gossip/examples/RunStandardExamples.java
new file mode 100644
index 0000000..21861bb
--- /dev/null
+++ b/gossip-examples/src/main/java/org/apache/gossip/examples/RunStandardExamples.java
@@ -0,0 +1,105 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.gossip.examples;
+
+import java.io.IOException;
+
+public class RunStandardExamples {
+
+  private static boolean WILL_READ = true;
+
+  private static boolean WILL_NOT_READ = false;
+
+  public static void main(String[] args) {
+    if ((args.length < 1) || args[0].equals("-h") || args[0].equals("--help") || args.length < 2) {
+      System.out.print(usage());
+      return;
+    }
+    try {
+      int example = intFromString(args[0]);
+      int channel = intFromString(args[1]);
+      if ((example < 1) || (example > 4) || (channel < 0) || (channel > 2)) {
+        System.out.print(usage());
+        return;
+      }
+      runExaple(example, channel);
+    } catch (Exception e) {
+      System.out.print(usage());
+    }
+  }
+
+  private static void runExaple(int exampleNumber, int channel) throws IOException {
+    String[] args = stanardArgs(channel, new String[4]);
+    if (exampleNumber == 1) {
+      StandAloneNode example = new StandAloneNode(args);
+      example.exec(WILL_NOT_READ);
+    } else if (exampleNumber == 2) {
+      StandAloneNodeCrdtOrSet example = new StandAloneNodeCrdtOrSet(args);
+      example.exec(WILL_READ);
+    } else if (exampleNumber == 3) {
+      StandAlonePNCounter example = new StandAlonePNCounter(args);
+      example.exec(WILL_READ);
+    } else if (exampleNumber == 4) {
+      args = extendedArgs(channel, new String[6]);
+      StandAloneDatacenterAndRack example = new StandAloneDatacenterAndRack(args);
+      example.exec(WILL_READ);
+    }
+  }
+
+  private static String[] stanardArgs(int channel, String[] args) {
+    // see README.md for examples
+    args[0] = "udp://localhost:1000" + channel;
+    args[1] = "" + channel;
+    args[2] = "udp://localhost:10000";
+    args[3] = "0";
+    return args;
+  }
+
+  private static String[] extendedArgs(int channel, String[] args) {
+    args = stanardArgs(channel, args);
+    // see README.md for examples
+    if (channel == 0) {
+      args[4] = "1";
+      args[5] = "2";
+    }
+    if (channel == 1) {
+      args[4] = "1";
+      args[5] = "3";
+    }
+    if (channel == 2) {
+      args[4] = "2";
+      args[5] = "2";
+    }
+    return args;
+  }
+
+  private static int intFromString(String string) {
+    return Integer.parseInt(string);
+  }
+
+  private static String usage() {
+    return "Select and run (usually in a seperate terminal window) \n"
+            + "one of the the standard Examples,\n" + " 1. StandAloneNode\n"
+            + " 2. StandAloneNodeCrdtOrSet\n" + " 3. StandAlonePNCounter\n"
+            + " 4. StandAloneDatacenterAndRack\n" + "(See README.md in this modules)\n" + "\n"
+            + "Usage: mvn exec:java -Dexec.mainClass=org.apache.gossip.examples.RunStandardExamples  -Dexec.args=\"s c\"\n"
+            + "where...\n" + "  s - int - the example number from above\n"
+            + "  c - int - the channel number: 0, 1, or 2\n";
+  }
+
+}

http://git-wip-us.apache.org/repos/asf/incubator-gossip/blob/1c673c85/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneDatacenterAndRack.java
----------------------------------------------------------------------
diff --git a/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneDatacenterAndRack.java b/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneDatacenterAndRack.java
index 1a2643c..2336e87 100644
--- a/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneDatacenterAndRack.java
+++ b/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneDatacenterAndRack.java
@@ -18,8 +18,8 @@
 
 package org.apache.gossip.examples;
 
+import java.io.IOException;
 import java.net.URI;
-import java.net.UnknownHostException;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
@@ -30,12 +30,20 @@ import org.apache.gossip.manager.DatacenterRackAwareActiveGossiper;
 import org.apache.gossip.manager.GossipManager;
 import org.apache.gossip.manager.GossipManagerBuilder;
 
-public class StandAloneDatacenterAndRack {
+public class StandAloneDatacenterAndRack extends StandAloneExampleBase {
 
-  private static ExampleCommon common = new ExampleCommon();
+  public static void main(String[] args) throws InterruptedException, IOException {
+    StandAloneDatacenterAndRack example = new StandAloneDatacenterAndRack(args);
+    boolean willRead = true;
+    example.exec(willRead);
+  }
+
+  StandAloneDatacenterAndRack(String[] args) {
+    args = super.checkArgsForClearFlag(args);
+    initGossipManager(args);
+  }
 
-  public static void main(String[] args) throws UnknownHostException, InterruptedException {
-    args = common.checkArgsForClearFlag(args);
+  void initGossipManager(String[] args) {
     GossipSettings s = new GossipSettings();
     s.setWindowSize(1000);
     s.setGossipInterval(100);
@@ -48,20 +56,17 @@ public class StandAloneDatacenterAndRack {
     props.put(DatacenterRackAwareActiveGossiper.DATACENTER, args[4]);
     props.put(DatacenterRackAwareActiveGossiper.RACK, args[5]);
     GossipManager manager = GossipManagerBuilder.newBuilder().cluster("mycluster")
-            .uri(URI.create(args[0]))
-            .id(args[1])
-            .gossipSettings(s)
+            .uri(URI.create(args[0])).id(args[1]).gossipSettings(s)
             .gossipMembers(
                     Arrays.asList(new RemoteMember("mycluster", URI.create(args[2]), args[3])))
-            .properties(props)
-            .build();
+            .properties(props).build();
     manager.init();
-    while (true) {
-      common.optionallyClearTerminal();
-      System.out.println("Live: " + manager.getLiveMembers());
-      System.out.println("Dead: " + manager.getDeadMembers());
-      Thread.sleep(2000);
-    }
+    setGossipService(manager);
+  }
+
+  @Override
+  void printValues(GossipManager gossipService) {
+    return;
   }
 
 }

http://git-wip-us.apache.org/repos/asf/incubator-gossip/blob/1c673c85/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneExampleBase.java
----------------------------------------------------------------------
diff --git a/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneExampleBase.java b/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneExampleBase.java
new file mode 100644
index 0000000..02c2ee7
--- /dev/null
+++ b/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneExampleBase.java
@@ -0,0 +1,162 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.gossip.examples;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.URI;
+import java.util.Collections;
+import java.util.List;
+
+import org.apache.gossip.GossipSettings;
+import org.apache.gossip.LocalMember;
+import org.apache.gossip.RemoteMember;
+import org.apache.gossip.manager.GossipManager;
+import org.apache.gossip.manager.GossipManagerBuilder;
+
+abstract class StandAloneExampleBase {
+  private String lastInput = "{none}";
+
+  private boolean clearTerminalScreen = true;
+
+  private GossipManager gossipService = null;
+
+  abstract void printValues(GossipManager gossipService);
+
+  boolean processReadLoopInput(String line) {
+    return true;
+  }
+
+  void exec(boolean willRead) throws IOException {
+    gossipService.init();
+    startMonitorLoop(gossipService);
+    if (willRead) {
+      startBlockingReadLoop();
+    }
+  }
+
+  /*
+   * Look for -s in args. If there, suppress terminal-clear on write results: shift args for
+   * positional args, if necessary
+   */
+  String[] checkArgsForClearFlag(String[] args) {
+    int pos = 0;
+    for (int i = 0; i < args.length; i++) {
+      if (args[i].equals("-s")) {
+        clearTerminalScreen = false;
+      } else {
+        // in the case of the -s flag, shift args
+        // down by one slot; this will end up with
+        // a duplicate entry in the last position of args,
+        // but this is ok, because it will be ignored
+        args[pos++] = args[i];
+      }
+    }
+    return args;
+  }
+
+  private void optionallyClearTerminal() {
+    if (clearTerminalScreen) {
+      System.out.print("\033[H\033[2J");
+      System.out.flush();
+    }
+  }
+
+  private void setLastInput(String input, boolean valid) {
+    lastInput = input;
+    if (!valid) {
+      lastInput += " (invalid)";
+    }
+  }
+
+  String getLastInput() {
+    return lastInput;
+  }
+
+  private void startMonitorLoop(GossipManager gossipService) {
+    new Thread(() -> {
+      while (true) {
+        optionallyClearTerminal();
+        printLiveMembers(gossipService);
+        printDeadMambers(gossipService);
+        printValues(gossipService);
+        try {
+          Thread.sleep(2000);
+        } catch (Exception ignore) {
+        }
+      }
+    }).start();
+  }
+
+  private void printLiveMembers(GossipManager gossipService) {
+    List<LocalMember> members = gossipService.getLiveMembers();
+    if (members.isEmpty()) {
+      System.out.println("Live: (none)");
+      return;
+    }
+    System.out.println("Live: " + members.get(0));
+    for (int i = 1; i < members.size(); i++) {
+      System.out.println("    : " + members.get(i));
+    }
+  }
+
+  private void printDeadMambers(GossipManager gossipService) {
+    List<LocalMember> members = gossipService.getDeadMembers();
+    if (members.isEmpty()) {
+      System.out.println("Dead: (none)");
+      return;
+    }
+    System.out.println("Dead: " + members.get(0));
+    for (int i = 1; i < members.size(); i++) {
+      System.out.println("    : " + members.get(i));
+    }
+  }
+
+  private void startBlockingReadLoop() throws IOException {
+    String line;
+    try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
+      while ((line = br.readLine()) != null) {
+        System.out.println(line);
+        boolean valid = processReadLoopInput(line);
+        setLastInput(line, valid);
+      }
+    }
+  }
+
+  void initGossipManager(String[] args) {
+    GossipSettings s = new GossipSettings();
+    s.setWindowSize(1000);
+    s.setGossipInterval(100);
+    GossipManager gossipService = GossipManagerBuilder.newBuilder().cluster("mycluster")
+            .uri(URI.create(args[0])).id(args[1])
+            .gossipMembers(Collections
+                    .singletonList(new RemoteMember("mycluster", URI.create(args[2]), args[3])))
+            .gossipSettings(s).build();
+    setGossipService(gossipService);
+  }
+
+  void setGossipService(GossipManager gossipService) {
+    this.gossipService = gossipService;
+  }
+
+  GossipManager getGossipManager() {
+    return this.gossipService;
+  }
+
+}

http://git-wip-us.apache.org/repos/asf/incubator-gossip/blob/1c673c85/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneNode.java
----------------------------------------------------------------------
diff --git a/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneNode.java b/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneNode.java
index 70c3e4d..953e784 100644
--- a/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneNode.java
+++ b/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneNode.java
@@ -17,37 +17,26 @@
  */
 package org.apache.gossip.examples;
 
-import java.net.URI;
-import java.net.UnknownHostException;
-import java.util.Arrays;
-import org.apache.gossip.GossipSettings;
-import org.apache.gossip.RemoteMember;
+import java.io.IOException;
+
 import org.apache.gossip.manager.GossipManager;
-import org.apache.gossip.manager.GossipManagerBuilder;
-
-public class StandAloneNode {
-
-  private static ExampleCommon common = new ExampleCommon();
-
-  public static void main(String[] args) throws UnknownHostException, InterruptedException {
-    args = common.checkArgsForClearFlag(args);
-    GossipSettings s = new GossipSettings();
-    s.setWindowSize(1000);
-    s.setGossipInterval(100);
-    GossipManager gossipService = GossipManagerBuilder.newBuilder().cluster("mycluster")
-            .uri(URI.create(args[0]))
-            .id(args[1])
-            .gossipMembers(
-                    Arrays.asList(new RemoteMember("mycluster", URI.create(args[2]), args[3])))
-            .gossipSettings(s)
-            .build();
-    gossipService.init();
-    while (true) {
-      common.optionallyClearTerminal();
-      System.out.println("Live: " + gossipService.getLiveMembers());
-      System.out.println("Dead: " + gossipService.getDeadMembers());
-      Thread.sleep(2000);
-    }
+
+public class StandAloneNode extends StandAloneExampleBase {
+
+  private static boolean WILL_READ = false;
+
+  public static void main(String[] args) throws InterruptedException, IOException {
+    StandAloneNode example = new StandAloneNode(args);
+    example.exec(WILL_READ);
+  }
+
+  StandAloneNode(String[] args) {
+    args = super.checkArgsForClearFlag(args);
+    super.initGossipManager(args);
+  }
+
+  @Override
+  void printValues(GossipManager gossipService) {
   }
 
 }

http://git-wip-us.apache.org/repos/asf/incubator-gossip/blob/1c673c85/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneNodeCrdtOrSet.java
----------------------------------------------------------------------
diff --git a/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneNodeCrdtOrSet.java b/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneNodeCrdtOrSet.java
index 78c7782..a184bc4 100644
--- a/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneNodeCrdtOrSet.java
+++ b/gossip-examples/src/main/java/org/apache/gossip/examples/StandAloneNodeCrdtOrSet.java
@@ -17,85 +17,89 @@
  */
 package org.apache.gossip.examples;
 
-import java.io.BufferedReader;
 import java.io.IOException;
-import java.io.InputStreamReader;
-import java.net.URI;
-import java.util.Arrays;
-import org.apache.gossip.GossipSettings;
-import org.apache.gossip.RemoteMember;
+
 import org.apache.gossip.crdt.GrowOnlyCounter;
 import org.apache.gossip.crdt.OrSet;
 import org.apache.gossip.manager.GossipManager;
-import org.apache.gossip.manager.GossipManagerBuilder;
 import org.apache.gossip.model.SharedDataMessage;
 
-public class StandAloneNodeCrdtOrSet {
+public class StandAloneNodeCrdtOrSet extends StandAloneExampleBase {
+
+  private static final String INDEX_KEY_FOR_SET = "abc";
 
-  private static ExampleCommon common = new ExampleCommon();
+  private static final String INDEX_KEY_FOR_COUNTER = "def";
 
   public static void main(String[] args) throws InterruptedException, IOException {
-    args = common.checkArgsForClearFlag(args);
-    GossipSettings s = new GossipSettings();
-    s.setWindowSize(1000);
-    s.setGossipInterval(100);
-    GossipManager gossipService = GossipManagerBuilder.newBuilder().cluster("mycluster")
-            .uri(URI.create(args[0]))
-            .id(args[1])
-            .gossipMembers(
-                    Arrays.asList(new RemoteMember("mycluster", URI.create(args[2]), args[3])))
-            .gossipSettings(s)
-            .build();
-    gossipService.init();
+    StandAloneNodeCrdtOrSet example = new StandAloneNodeCrdtOrSet(args);
+    boolean willRead = true;
+    example.exec(willRead);
+  }
 
-    new Thread(() -> {
-      while (true) {
-        common.optionallyClearTerminal();
-        System.out.println("Live: " + gossipService.getLiveMembers());
-        System.out.println("Dead: " + gossipService.getDeadMembers());
-        System.out.println("---------- " + (gossipService.findCrdt("abc") == null ? ""
-                : gossipService.findCrdt("abc").value()));
-        System.out.println("********** " + gossipService.findCrdt("abc"));
-        System.out.println("^^^^^^^^^^ " + (gossipService.findCrdt("def") == null ? ""
-                : gossipService.findCrdt("def").value()));
-        System.out.println("$$$$$$$$$$ " + gossipService.findCrdt("def"));
-        try {
-          Thread.sleep(2000);
-        } catch (Exception e) {
-        }
-      }
-    }).start();
+  StandAloneNodeCrdtOrSet(String[] args) {
+    args = super.checkArgsForClearFlag(args);
+    super.initGossipManager(args);
+  }
+
+  void printValues(GossipManager gossipService) {
+    System.out.println("Last Input: " + getLastInput());
+    System.out.println("---------- Or Set " + (gossipService.findCrdt(INDEX_KEY_FOR_SET) == null
+            ? "" : gossipService.findCrdt(INDEX_KEY_FOR_SET).value()));
+    System.out.println("********** " + gossipService.findCrdt(INDEX_KEY_FOR_SET));
+    System.out.println(
+            "^^^^^^^^^^ Grow Only Counter" + (gossipService.findCrdt(INDEX_KEY_FOR_COUNTER) == null
+                    ? "" : gossipService.findCrdt(INDEX_KEY_FOR_COUNTER).value()));
+    System.out.println("$$$$$$$$$$ " + gossipService.findCrdt(INDEX_KEY_FOR_COUNTER));
+  }
 
-    String line = null;
-    try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
-      while ((line = br.readLine()) != null) {
-        System.out.println(line);
-        char op = line.charAt(0);
-        String val = line.substring(2);
-        if (op == 'a') {
-          addData(val, gossipService);
-        } else if (op == 'r') {
-          removeData(val, gossipService);
-        } else if (op == 'g') {
-          gcount(val, gossipService);
-        }
-        if (op == 'l') {
-          listen(val, gossipService);
-        }
+  boolean processReadLoopInput(String line) {
+    boolean valid = true;
+    char op = line.charAt(0);
+    String val = line.substring(2);
+    if (op == 'a') {
+      addData(val, getGossipManager());
+    } else if (op == 'r') {
+      removeData(val, getGossipManager());
+    } else if (op == 'g') {
+      if (isNonNegativeNumber(val)) {
+        gcount(val, getGossipManager());
+      } else {
+        valid = false;
       }
+    } else if (op == 'l') {
+      if ((val == INDEX_KEY_FOR_SET) || (val == INDEX_KEY_FOR_COUNTER)) {
+        listen(val, getGossipManager());
+      } else {
+        valid = false;
+      }
+    } else {
+      valid = false;
     }
+    return valid;
   }
-  
+
+  private boolean isNonNegativeNumber(String val) {
+    long l = 0;
+    try {
+      Long n = Long.parseLong(val);
+      l = n.longValue();
+    } catch (Exception e) {
+      return false;
+    }
+    return (l >= 0);
+  }
+
   private static void listen(String val, GossipManager gossipManager) {
     gossipManager.registerSharedDataSubscriber((key, oldValue, newValue) -> {
       if (key.equals(val)) {
-        System.out.println("Event Handler fired! " + oldValue + " " + newValue);
+        System.out.println(
+                "Event Handler fired for key = '" + key + "'! " + oldValue + " " + newValue);
       }
     });
   }
-  
+
   private static void gcount(String val, GossipManager gossipManager) {
-    GrowOnlyCounter c = (GrowOnlyCounter) gossipManager.findCrdt("def");
+    GrowOnlyCounter c = (GrowOnlyCounter) gossipManager.findCrdt(INDEX_KEY_FOR_COUNTER);
     Long l = Long.valueOf(val);
     if (c == null) {
       c = new GrowOnlyCounter(new GrowOnlyCounter.Builder(gossipManager).increment((l)));
@@ -104,7 +108,7 @@ public class StandAloneNodeCrdtOrSet {
     }
     SharedDataMessage m = new SharedDataMessage();
     m.setExpireAt(Long.MAX_VALUE);
-    m.setKey("def");
+    m.setKey(INDEX_KEY_FOR_COUNTER);
     m.setPayload(c);
     m.setTimestamp(System.currentTimeMillis());
     gossipManager.merge(m);
@@ -112,10 +116,10 @@ public class StandAloneNodeCrdtOrSet {
 
   private static void removeData(String val, GossipManager gossipService) {
     @SuppressWarnings("unchecked")
-    OrSet<String> s = (OrSet<String>) gossipService.findCrdt("abc");
+    OrSet<String> s = (OrSet<String>) gossipService.findCrdt(INDEX_KEY_FOR_SET);
     SharedDataMessage m = new SharedDataMessage();
     m.setExpireAt(Long.MAX_VALUE);
-    m.setKey("abc");
+    m.setKey(INDEX_KEY_FOR_SET);
     m.setPayload(new OrSet<String>(s, new OrSet.Builder<String>().remove(val)));
     m.setTimestamp(System.currentTimeMillis());
     gossipService.merge(m);
@@ -124,7 +128,7 @@ public class StandAloneNodeCrdtOrSet {
   private static void addData(String val, GossipManager gossipService) {
     SharedDataMessage m = new SharedDataMessage();
     m.setExpireAt(Long.MAX_VALUE);
-    m.setKey("abc");
+    m.setKey(INDEX_KEY_FOR_SET);
     m.setPayload(new OrSet<String>(val));
     m.setTimestamp(System.currentTimeMillis());
     gossipService.merge(m);

http://git-wip-us.apache.org/repos/asf/incubator-gossip/blob/1c673c85/gossip-examples/src/main/java/org/apache/gossip/examples/StandAlonePNCounter.java
----------------------------------------------------------------------
diff --git a/gossip-examples/src/main/java/org/apache/gossip/examples/StandAlonePNCounter.java b/gossip-examples/src/main/java/org/apache/gossip/examples/StandAlonePNCounter.java
index b0015be..23e949b 100644
--- a/gossip-examples/src/main/java/org/apache/gossip/examples/StandAlonePNCounter.java
+++ b/gossip-examples/src/main/java/org/apache/gossip/examples/StandAlonePNCounter.java
@@ -17,116 +17,55 @@
  */
 package org.apache.gossip.examples;
 
-import java.io.BufferedReader;
 import java.io.IOException;
-import java.io.InputStreamReader;
-import java.net.URI;
-import java.util.Arrays;
-import java.util.List;
 
-import org.apache.gossip.GossipSettings;
-import org.apache.gossip.LocalMember;
-import org.apache.gossip.RemoteMember;
 import org.apache.gossip.crdt.PNCounter;
 import org.apache.gossip.manager.GossipManager;
-import org.apache.gossip.manager.GossipManagerBuilder;
 import org.apache.gossip.model.SharedDataMessage;
 
-public class StandAlonePNCounter {
-  private static ExampleCommon common = new ExampleCommon();
-  private static String lastInput = "{None}";
+public class StandAlonePNCounter extends StandAloneExampleBase {
 
   public static void main(String[] args) throws InterruptedException, IOException {
-    args = common.checkArgsForClearFlag(args);
-    GossipSettings s = new GossipSettings();
-    s.setWindowSize(1000);
-    s.setGossipInterval(100);
-    GossipManager gossipService = GossipManagerBuilder
-            .newBuilder()
-            .cluster("mycluster")
-            .uri(URI.create(args[0])).id(args[1])
-            .gossipMembers(
-                    Arrays.asList(new RemoteMember("mycluster", URI.create(args[2]), args[3])))
-            .gossipSettings(s)
-            .build();
-    gossipService.init();
-
-    new Thread(() -> {
-      while (true) {
-        common.optionallyClearTerminal();
-        printLiveMembers(gossipService);
-        printDeadMambers(gossipService);
-        printValues(gossipService);
-        try {
-          Thread.sleep(2000);
-        } catch (Exception ignore) {
-        }
-      }
-    }).start();
+    StandAlonePNCounter example = new StandAlonePNCounter(args);
+    boolean willRead = true;
+    example.exec(willRead);
+  }
 
-    String line = null;
-    try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in))) {
-      while ((line = br.readLine()) != null) {
-        System.out.println(line);
-        char op = line.charAt(0);
-        char blank = line.charAt(1);
-        String val = line.substring(2);
-        Long l = null;
-        boolean valid = true;
-        try {
-           l = Long.valueOf(val);
-        } catch (NumberFormatException ex) {
-          valid = false;
-        }
-        valid = valid &&
-          (
-            (blank == ' ') &&
-            ((op == 'i') || (op == 'd'))
-          );
-        if (valid) {
-          if (op == 'i') {
-            increment(l, gossipService);
-          } else if (op == 'd') {
-            decrement(l, gossipService);
-          }
-        }
-        setLastInput(line,valid);
-      }
-    }
+  StandAlonePNCounter(String[] args) {
+    args = super.checkArgsForClearFlag(args);
+    super.initGossipManager(args);
   }
 
-  private static void printValues(GossipManager gossipService) {
+  void printValues(GossipManager gossipService) {
     System.out.println("Last Input: " + getLastInput());
     System.out.println("---------- " + (gossipService.findCrdt("myPNCounter") == null ? ""
             : gossipService.findCrdt("myPNCounter").value()));
     System.out.println("********** " + gossipService.findCrdt("myPNCounter"));
   }
 
-  private static void printDeadMambers(GossipManager gossipService) {
-    List<LocalMember> members = gossipService.getDeadMembers();
-    if (members.isEmpty()) {
-       System.out.println("Dead: (none)");
-       return;
-    }
-    System.out.println("Dead: " + members.get(0));
-    for (int i = 1; i < members.size(); i++) {
-      System.out.println("    : " + members.get(i)); 
-    }
-  }
-
-  private static void printLiveMembers(GossipManager gossipService) {
-    List<LocalMember> members = gossipService.getLiveMembers();
-    if (members.isEmpty()) {
-       System.out.println("Live: (none)");
-       return;
+  boolean processReadLoopInput(String line) {
+    char op = line.charAt(0);
+    char blank = line.charAt(1);
+    String val = line.substring(2);
+    Long l = null;
+    boolean valid = true;
+    try {
+      l = Long.valueOf(val);
+    } catch (NumberFormatException ex) {
+      valid = false;
     }
-    System.out.println("Live: " + members.get(0));
-    for (int i = 1; i < members.size(); i++) {
-      System.out.println("    : " + members.get(i)); 
+    valid = valid && ((blank == ' ') && ((op == 'i') || (op == 'd')));
+    if (valid) {
+      if (op == 'i') {
+        increment(l, getGossipManager());
+      } else if (op == 'd') {
+        decrement(l, getGossipManager());
+      }
     }
+    return valid;
   }
 
-  private static void increment(Long l, GossipManager gossipManager) {
+  void increment(Long l, GossipManager gossipManager) {
     PNCounter c = (PNCounter) gossipManager.findCrdt("myPNCounter");
     if (c == null) {
       c = new PNCounter(new PNCounter.Builder(gossipManager).increment((l)));
@@ -141,7 +80,7 @@ public class StandAlonePNCounter {
     gossipManager.merge(m);
   }
 
-  private static void decrement(Long l, GossipManager gossipManager) {
+  void decrement(Long l, GossipManager gossipManager) {
     PNCounter c = (PNCounter) gossipManager.findCrdt("myPNCounter");
     if (c == null) {
       c = new PNCounter(new PNCounter.Builder(gossipManager).decrement((l)));
@@ -155,16 +94,5 @@ public class StandAlonePNCounter {
     m.setTimestamp(System.currentTimeMillis());
     gossipManager.merge(m);
   }
-  
-  private static void setLastInput(String input, boolean valid) {
-    lastInput = input;
-    if (! valid) {
-      lastInput += " (invalid)";
-    }
-  }
-
-  private static String getLastInput() {
-    return lastInput;
-  }
 
 }
\ No newline at end of file