Merge branch 'develop' of github.com:Agorise/graphenej into develop

graphenej/src/main/java/cy/agorise/graphenej/api/android/NetworkService.java

@@ -80,7 +80,7 @@ public class NetworkService extends Service {
     private final String TAG = this.getClass().getName();
 
     public static final int NORMAL_CLOSURE_STATUS = 1000;
-    private static final int NO_HISTORY_CLOSURE_STATUS = 1001;
+    private static final int GOING_AWAY_STATUS = 1001;
 
     // Time to wait before retrying a connection attempt
     private static final int DEFAULT_RETRY_DELAY = 500;
@@ -341,6 +341,14 @@ public class NetworkService extends Service {
         }
     }
 
+    /**
+     * Public method that can be called from classes that bind to the service and find out that
+     * for any reason want the service to connect to a different node.
+     */
+    public void removeCurrentNodeAndReconnect() {
+        mWebSocket.close(GOING_AWAY_STATUS, null);
+    }
+
     /**
      * Runnable that will perform a connection attempt with the best node after DEFAULT_INITIAL_DELAY
      * milliseconds. This is used only if the node latency verification is activated.
@@ -566,9 +574,6 @@ public class NetworkService extends Service {
                     } else if (requestClass == GetFullAccounts.class) {
                         Type GetFullAccountsResponse = new TypeToken<JsonRpcResponse<List<FullAccountDetails>>>(){}.getType();
                         parsedResponse = gson.fromJson(text, GetFullAccountsResponse);
-
-                        if(parsedResponse != null)
-                            verifyNodeHasHistoryApi(parsedResponse);
                     } else if(requestClass == GetKeyReferences.class){
                         Type GetKeyReferencesResponse = new TypeToken<JsonRpcResponse<List<List<UserAccount>>>>(){}.getType();
                         parsedResponse = gson.fromJson(text, GetKeyReferencesResponse);
@@ -591,30 +596,6 @@ public class NetworkService extends Service {
             RxBus.getBusInstance().send(parsedResponse);
         }
 
-        /**
-         * This method inspects the node response to find out if the totalOps is equal to zero,
-         * in that case the current connected node may not have the history plugin so we would need
-         * to close the connection and choose a different node.
-         *
-         * @param parsedResponse A JSONRpcResponse from a GetFullAccounts API call
-         */
-        private void verifyNodeHasHistoryApi(JsonRpcResponse parsedResponse) {
-            if(parsedResponse.result instanceof List &&
-                    ((List) parsedResponse.result).size() > 0 &&
-                    ((List) parsedResponse.result).get(0) instanceof FullAccountDetails) {
-
-                FullAccountDetails fullAccountDetails = (FullAccountDetails) ((List) parsedResponse.result).get(0);
-                long totalOps = fullAccountDetails.getStatistics().total_ops;
-
-                if (totalOps == 0) {
-                    Log.d(TAG, "The node returned 0 total_ops for current account and may not have installed the history plugin. " +
-                            "Trying to connect to a different node.");
-
-                    mWebSocket.close(NO_HISTORY_CLOSURE_STATUS, null);
-                }
-            }
-        }
-
         /**
          * Private method that will just broadcast a de-serialized notification to all interested parties
          * @param notification  De-serialized notification
@@ -674,10 +655,10 @@ public class NetworkService extends Service {
             super.onClosed(webSocket, code, reason);
             Log.d(TAG,"onClosed");
 
-            if (code == NO_HISTORY_CLOSURE_STATUS)
+            if (code == GOING_AWAY_STATUS)
-                handleWebSocketDisconnection(true);
+                handleWebSocketDisconnection(true, true);
             else
-                handleWebSocketDisconnection(false);
+                handleWebSocketDisconnection(false, false);
         }
 
         @Override
@@ -694,16 +675,17 @@ public class NetworkService extends Service {
                 Log.e(TAG,"Response: "+response.message());
             }
 
-            handleWebSocketDisconnection(true);
+            handleWebSocketDisconnection(true, false);
         }
 
         /**
          * Method that encapsulates the behavior of handling a disconnection to the current node, and
          * potentially tries to reconnect to another one.
          *
-         * @param tryReconnection Variable that states if a reconnection to other node should be tried.
+         * @param tryReconnection       States if a reconnection to other node should be tried.
+         * @param removeSelectedNode    States if the current node should be removed from the nodes list.
          */
-        private void handleWebSocketDisconnection(boolean tryReconnection) {
+        private void handleWebSocketDisconnection(boolean tryReconnection, boolean removeSelectedNode) {
             RxBus.getBusInstance().send(new ConnectionStatusUpdate(ConnectionStatusUpdate.DISCONNECTED, ApiAccess.API_NONE));
 
             isLoggedIn = false;
@@ -720,10 +702,18 @@ public class NetworkService extends Service {
                 mCurrentId = 0;
                 mApiIds.clear();
 
+                if (removeSelectedNode) {
+                    // Remove node from node provider so that it is not returned for following connections
+                    nodeProvider.removeNode(mSelectedNode);
+
+                    // Remove node from nodeLatencyVerifier, so that it publishes its removal
+                    nodeLatencyVerifier.removeNode(mSelectedNode);
+                } else {
                     // Adding a very high latency value to this node in order to prevent
                     // us from getting it again
                     mSelectedNode.addLatencyValue(Long.MAX_VALUE);
                     nodeProvider.updateNode(mSelectedNode);
+                }
 
                 RxBus.getBusInstance().send(new ConnectionStatusUpdate(ConnectionStatusUpdate.DISCONNECTED, ApiAccess.API_NONE));
 

graphenej/src/main/java/cy/agorise/graphenej/network/FullNode.java

@@ -10,6 +10,7 @@ public class FullNode implements Comparable {
     private String mUrl;
     private ExponentialMovingAverage mLatency;
     private boolean isConnected;
+    private boolean isRemoved;
 
     private FullNode(){}
 
@@ -77,6 +78,14 @@ public class FullNode implements Comparable {
         isConnected = connected;
     }
 
+    public boolean isRemoved() {
+        return isRemoved;
+    }
+
+    public void setRemoved(boolean removed) {
+        isRemoved = removed;
+    }
+
     /**
      * Method that updates the mLatency average with a new value.
      * @param latency   Most recent mLatency sample to be added to the exponential average

graphenej/src/main/java/cy/agorise/graphenej/network/LatencyNodeProvider.java

@@ -3,13 +3,14 @@ package cy.agorise.graphenej.network;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
-import java.util.PriorityQueue;
+import java.util.concurrent.PriorityBlockingQueue;
 
 public class LatencyNodeProvider implements NodeProvider {
-    private PriorityQueue<FullNode> mFullNodeHeap;
+
+    private PriorityBlockingQueue<FullNode> mFullNodeHeap;
 
     public LatencyNodeProvider(){
-        mFullNodeHeap = new PriorityQueue<>();
+        mFullNodeHeap = new PriorityBlockingQueue<>();
     }
 
     @Override
@@ -24,9 +25,12 @@ public class LatencyNodeProvider implements NodeProvider {
 
     @Override
     public boolean updateNode(FullNode fullNode) {
-        mFullNodeHeap.remove(fullNode);
+        boolean existed = mFullNodeHeap.remove(fullNode);
+        if(existed){
             return mFullNodeHeap.offer(fullNode);
         }
+        return false;
+    }
 
     /**
      * Updates an existing node with the new latency value.
@@ -36,12 +40,16 @@ public class LatencyNodeProvider implements NodeProvider {
      * @return          True if the node priority was updated successfully
      */
     public boolean updateNode(FullNode fullNode, int latency){
-        if(mFullNodeHeap.remove(fullNode)){
+        boolean existed = mFullNodeHeap.remove(fullNode);
-            fullNode.addLatencyValue(latency);
+        if(existed){
             return mFullNodeHeap.add(fullNode);
-        }else{
+        }
         return false;
     }
+
+    @Override
+    public void removeNode(FullNode fullNode) {
+        mFullNodeHeap.remove(fullNode);
     }
 
     @Override

graphenej/src/main/java/cy/agorise/graphenej/network/NodeLatencyVerifier.java

@@ -183,4 +183,24 @@ public class NodeLatencyVerifier {
             }
         }
     }
+
+    /**
+     * Removes the given node from the nodes list
+     * @param fullNode The node to remove
+     */
+    public void removeNode(FullNode fullNode){
+        for(FullNode node : mNodeList){
+            if(node.equals(fullNode)){
+                mNodeList.remove(node);
+
+                String normalURL = node.getUrl().replace("wss://", "https://");
+                HttpUrl key = HttpUrl.parse(normalURL);
+                nodeURLMap.remove(key);
+
+                node.setRemoved(true);
+                subject.onNext(node);
+                break;
+            }
+        }
+    }
 }

graphenej/src/main/java/cy/agorise/graphenej/network/NodeProvider.java

@@ -26,13 +26,19 @@ public interface NodeProvider {
 
     /**
      * Updates the rating of a specific node that is already in the NodeProvider
-     * @param fullNode
+     * @param fullNode The node tu update
      */
     boolean updateNode(FullNode fullNode);
 
+    /**
+     * Removes the given node from the nodes list
+     * @param fullNode The node to remove
+     */
+    void removeNode(FullNode fullNode);
+
     /**
      * Returns an ordered list of {@link FullNode} instances.
-     * @return
+     * @return The sorted list of nodes.
      */
     List<FullNode> getSortedNodes();
 }

sample/src/main/AndroidManifest.xml

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
     package="cy.agorise.labs.sample">
 
     <uses-permission android:name="android.permission.INTERNET" />
@@ -11,7 +12,8 @@
         android:label="@string/app_name"
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
-        android:theme="@style/AppTheme">
+        android:theme="@style/AppTheme"
+        tools:ignore="GoogleAppIndexingWarning">
         <activity android:name=".SubscriptionActivity" />
         <activity android:name=".CallsActivity">
             <intent-filter>
@@ -19,7 +21,8 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
-        <activity android:name=".PerformCallActivity"></activity>
+        <activity android:name=".PerformCallActivity" />
+        <activity android:name=".RemoveNodeActivity" />
     </application>
 
 </manifest>

sample/src/main/java/cy/agorise/labs/sample/CallsActivity.java

@@ -25,6 +25,8 @@ import io.reactivex.functions.Consumer;
 public class CallsActivity extends AppCompatActivity {
     private final String TAG = this.getClass().getName();
 
+    private static final String REMOVE_CURRENT_NODE = "remove_current_node";
+
     @BindView(R.id.call_list)
     RecyclerView mRecyclerView;
 
@@ -75,7 +77,8 @@ public class CallsActivity extends AppCompatActivity {
             RPC.CALL_SET_SUBSCRIBE_CALLBACK,
             RPC.CALL_GET_DYNAMIC_GLOBAL_PROPERTIES,
             RPC.CALL_GET_KEY_REFERENCES,
-            RPC.CALL_GET_ACCOUNT_BALANCES
+            RPC.CALL_GET_ACCOUNT_BALANCES,
+            REMOVE_CURRENT_NODE
         };
 
         @NonNull
@@ -96,6 +99,8 @@ public class CallsActivity extends AppCompatActivity {
                 Intent intent;
                 if(selectedCall.equals(RPC.CALL_SET_SUBSCRIBE_CALLBACK)){
                     intent = new Intent(CallsActivity.this, SubscriptionActivity.class);
+                } else if (selectedCall.equals(REMOVE_CURRENT_NODE)){
+                    intent = new Intent(CallsActivity.this, RemoveNodeActivity.class);
                 }else{
                     intent = new Intent(CallsActivity.this, PerformCallActivity.class);
                     intent.putExtra(Constants.KEY_SELECTED_CALL, selectedCall);

sample/src/main/java/cy/agorise/labs/sample/RemoveNodeActivity.java

@@ -0,0 +1,286 @@
+package cy.agorise.labs.sample;
+
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.content.ServiceConnection;
+import android.graphics.Color;
+import android.graphics.Typeface;
+import android.os.Build;
+import android.os.Bundle;
+import android.os.IBinder;
+import android.support.annotation.NonNull;
+import android.support.v4.content.ContextCompat;
+import android.support.v7.app.AppCompatActivity;
+import android.support.v7.util.SortedList;
+import android.support.v7.widget.LinearLayoutManager;
+import android.support.v7.widget.RecyclerView;
+import android.text.SpannableStringBuilder;
+import android.text.Spanned;
+import android.text.style.ForegroundColorSpan;
+import android.text.style.StyleSpan;
+import android.util.Log;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ImageView;
+import android.widget.TextView;
+
+import java.util.Comparator;
+import java.util.List;
+import java.util.Locale;
+
+import butterknife.BindView;
+import butterknife.ButterKnife;
+import butterknife.OnClick;
+import cy.agorise.graphenej.api.android.NetworkService;
+import cy.agorise.graphenej.network.FullNode;
+import io.reactivex.Observer;
+import io.reactivex.android.schedulers.AndroidSchedulers;
+import io.reactivex.disposables.Disposable;
+import io.reactivex.subjects.PublishSubject;
+
+public class RemoveNodeActivity extends AppCompatActivity implements ServiceConnection {
+
+    private final String TAG = this.getClass().getName();
+
+    @BindView(R.id.rvNodes)
+    RecyclerView rvNodes;
+
+    FullNodesAdapter nodesAdapter;
+
+    // Comparator used to sort the nodes in ascending order
+    private final Comparator<FullNode> LATENCY_COMPARATOR = (a, b) ->
+            Double.compare(a.getLatencyValue(), b.getLatencyValue());
+
+    /* Network service connection */
+    private NetworkService mNetworkService;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_remove_node);
+
+        ButterKnife.bind(this);
+
+        rvNodes.setLayoutManager(new LinearLayoutManager(this));
+        nodesAdapter = new FullNodesAdapter(this, LATENCY_COMPARATOR);
+        rvNodes.setAdapter(nodesAdapter);
+    }
+
+    @OnClick(R.id.btnRemoveCurrentNode)
+    public void removeCurrentNode() {
+        mNetworkService.removeCurrentNodeAndReconnect();
+    }
+
+    @Override
+    public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
+        // We've bound to LocalService, cast the IBinder and get LocalService instance
+        NetworkService.LocalBinder binder = (NetworkService.LocalBinder) iBinder;
+        mNetworkService = binder.getService();
+
+        if(mNetworkService != null){
+            // PublishSubject used to announce full node latencies updates
+            PublishSubject<FullNode> fullNodePublishSubject = mNetworkService.getNodeLatencyObservable();
+            if(fullNodePublishSubject != null)
+                fullNodePublishSubject.observeOn(AndroidSchedulers.mainThread()).subscribe(nodeLatencyObserver);
+
+            List<FullNode> fullNodes = mNetworkService.getNodes();
+            nodesAdapter.add(fullNodes);
+        }
+    }
+
+    @Override
+    public void onServiceDisconnected(ComponentName componentName) {
+        mNetworkService = null;
+    }
+
+    /**
+     * Observer used to be notified about node latency measurement updates.
+     */
+    private Observer<FullNode> nodeLatencyObserver = new Observer<FullNode>() {
+        @Override
+        public void onSubscribe(Disposable d) { }
+
+        @Override
+        public void onNext(FullNode fullNode) {
+            if (!fullNode.isRemoved())
+                nodesAdapter.add(fullNode);
+            else
+                nodesAdapter.remove(fullNode);
+        }
+
+        @Override
+        public void onError(Throwable e) {
+            Log.e(TAG,"nodeLatencyObserver.onError.Msg: "+e.getMessage());
+        }
+
+        @Override
+        public void onComplete() { }
+    };
+
+    @Override
+    protected void onStart() {
+        super.onStart();
+        // Bind to LocalService
+        Intent intent = new Intent(this, NetworkService.class);
+        bindService(intent, this, Context.BIND_AUTO_CREATE);
+    }
+
+    @Override
+    protected void onPause() {
+        super.onPause();
+        unbindService(this);
+    }
+
+    class FullNodesAdapter extends RecyclerView.Adapter<FullNodesAdapter.ViewHolder> {
+
+        class ViewHolder extends RecyclerView.ViewHolder {
+            ImageView   ivNodeStatus;
+            TextView    tvNodeName;
+
+            ViewHolder(View itemView) {
+                super(itemView);
+
+                ivNodeStatus    = itemView.findViewById(R.id.ivNodeStatus);
+                tvNodeName      = itemView.findViewById(R.id.tvNodeName);
+            }
+        }
+
+        private final SortedList<FullNode> mSortedList = new SortedList<>(FullNode.class, new SortedList.Callback<FullNode>() {
+            @Override
+            public void onInserted(int position, int count) {
+                notifyItemRangeInserted(position, count);
+            }
+
+            @Override
+            public void onRemoved(int position, int count) {
+                notifyItemRangeRemoved(position, count);
+            }
+
+            @Override
+            public void onMoved(int fromPosition, int toPosition) {
+                notifyItemMoved(fromPosition, toPosition);
+            }
+
+            @Override
+            public void onChanged(int position, int count) {
+                notifyItemRangeChanged(position, count);
+            }
+
+            @Override
+            public int compare(FullNode a, FullNode b) {
+                return mComparator.compare(a, b);
+            }
+
+            @Override
+            public boolean areContentsTheSame(FullNode oldItem, FullNode newItem) {
+                return oldItem.getLatencyValue() == newItem.getLatencyValue();
+            }
+
+            @Override
+            public boolean areItemsTheSame(FullNode item1, FullNode item2) {
+                return item1.getUrl().equals(item2.getUrl());
+            }
+        });
+
+        private final Comparator<FullNode> mComparator;
+
+        private Context mContext;
+
+        FullNodesAdapter(Context context, Comparator<FullNode> comparator) {
+            mContext = context;
+            mComparator = comparator;
+        }
+
+        private Context getContext() {
+            return mContext;
+        }
+
+        @NonNull
+        @Override
+        public FullNodesAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
+            Context context = parent.getContext();
+            LayoutInflater inflater = LayoutInflater.from(context);
+
+            View transactionView = inflater.inflate(R.layout.item_node, parent, false);
+
+            return new ViewHolder(transactionView);
+        }
+
+        @Override
+        public void onBindViewHolder(@NonNull ViewHolder viewHolder, int position) {
+            final FullNode fullNode = mSortedList.get(position);
+
+            // Show the green check mark before the node name if that node is the one being used
+            if (fullNode.isConnected())
+                viewHolder.ivNodeStatus.setImageResource(R.drawable.ic_connected);
+            else
+                viewHolder.ivNodeStatus.setImageDrawable(null);
+
+            double latency = fullNode.getLatencyValue();
+
+            // Select correct color span according to the latency value
+            ForegroundColorSpan colorSpan;
+
+            if (latency < 400)
+                colorSpan = new ForegroundColorSpan(ContextCompat.getColor(getContext(), R.color.colorPrimary));
+            else if (latency < 800)
+                colorSpan = new ForegroundColorSpan(Color.rgb(255,136,0)); // Holo orange
+            else
+                colorSpan = new ForegroundColorSpan(Color.rgb(204,0,0)); // Holo red
+
+            // Create a string with the latency number colored according to their amount
+            SpannableStringBuilder ssb = new SpannableStringBuilder();
+
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+                ssb.append(fullNode.getUrl().replace("wss://", ""), new StyleSpan(Typeface.BOLD), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+            }
+            ssb.append(" (");
+
+            // 2000 ms is the timeout of the websocket used to calculate the latency, therefore if the
+            // received latency is greater than such value we can assume the node was not reachable.
+            String ms = latency < 2000 ? String.format(Locale.US, "%.0f ms", latency) : "??";
+
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+                ssb.append(ms, colorSpan, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+            }
+            ssb.append(")");
+
+            viewHolder.tvNodeName.setText(ssb);
+        }
+
+        /**
+         * Functions that adds/updates a FullNode to the SortedList
+         */
+        public void add(FullNode fullNode) {
+            // Remove the old instance of the FullNode before adding a new one. My understanding is that
+            // the sorted list should be able to automatically find repeated elements and update them
+            // instead of adding duplicates but it wasn't working so I opted for manually removing old
+            // instances of FullNodes before adding the updated ones.
+            int removed = 0;
+            for (int i=0;  i<mSortedList.size(); i++)
+            if (mSortedList.get(i - removed).getUrl().equals(fullNode.getUrl()))
+                mSortedList.removeItemAt(i-removed++);
+
+            mSortedList.add(fullNode);
+        }
+
+        /**
+         * Function that adds a whole list of nodes to the SortedList. It should only be used at the
+         * moment of populating the SortedList for the first time.
+         */
+        public void add(List<FullNode> fullNodes) {
+            mSortedList.addAll(fullNodes);
+        }
+
+        public void remove(FullNode fullNode) {
+            mSortedList.remove(fullNode);
+        }
+
+        @Override
+        public int getItemCount() {
+            return mSortedList.size();
+        }
+    }
+}

sample/src/main/res/drawable/ic_connected.xml

@@ -0,0 +1,5 @@
+<vector android:height="24dp" android:tint="#32C832"
+    android:viewportHeight="24.0" android:viewportWidth="24.0"
+    android:width="24dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="#FF000000" android:pathData="M19,3L5,3c-1.11,0 -2,0.9 -2,2v14c0,1.1 0.89,2 2,2h14c1.11,0 2,-0.9 2,-2L21,5c0,-1.1 -0.89,-2 -2,-2zM10,17l-5,-5 1.41,-1.41L10,14.17l7.59,-7.59L19,8l-9,9z"/>
+</vector>

sample/src/main/res/layout/activity_calls.xml

@@ -4,6 +4,6 @@
     android:id="@+id/call_list"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    tools:context=".CallsActivity">
+    tools:context=".CallsActivity"
-
+    tools:listitem="@layout/item_call"
-</android.support.v7.widget.RecyclerView>
+    tools:itemCount="5"/>

sample/src/main/res/layout/activity_perform_call.xml

@@ -11,8 +11,6 @@
         android:layout_width="match_parent"
         android:layout_height="0dp"
         android:layout_marginEnd="8dp"
-        android:layout_marginLeft="8dp"
-        android:layout_marginRight="8dp"
         android:layout_marginStart="8dp"
         android:layout_marginTop="8dp"
         app:layout_constraintBottom_toTopOf="@+id/container_param1"
@@ -32,8 +30,6 @@
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_marginEnd="8dp"
-        android:layout_marginLeft="8dp"
-        android:layout_marginRight="8dp"
         android:layout_marginStart="8dp"
         app:layout_constraintBottom_toTopOf="@+id/container_param2"
         app:layout_constraintEnd_toEndOf="parent"
@@ -51,8 +47,6 @@
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_marginEnd="8dp"
-        android:layout_marginLeft="8dp"
-        android:layout_marginRight="8dp"
         android:layout_marginStart="8dp"
         app:layout_constraintBottom_toTopOf="@+id/container_param3"
         app:layout_constraintEnd_toEndOf="parent"
@@ -69,8 +63,6 @@
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_marginEnd="8dp"
-        android:layout_marginLeft="8dp"
-        android:layout_marginRight="8dp"
         android:layout_marginStart="8dp"
         app:layout_constraintBottom_toTopOf="@+id/container_param4"
         app:layout_constraintEnd_toEndOf="parent"
@@ -87,8 +79,6 @@
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_marginEnd="8dp"
-        android:layout_marginLeft="8dp"
-        android:layout_marginRight="8dp"
         android:layout_marginStart="8dp"
         app:layout_constraintBottom_toTopOf="@+id/button_send"
         app:layout_constraintEnd_toEndOf="parent"
@@ -106,8 +96,6 @@
         android:layout_height="wrap_content"
         android:layout_marginBottom="8dp"
         android:layout_marginEnd="8dp"
-        android:layout_marginLeft="8dp"
-        android:layout_marginRight="8dp"
         android:layout_marginStart="8dp"
         android:text="@string/action_send"
         app:layout_constraintBottom_toBottomOf="parent"

sample/src/main/res/layout/activity_remove_node.xml

@@ -0,0 +1,25 @@
+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools">
+
+    <android.support.v7.widget.RecyclerView
+        android:id="@+id/rvNodes"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintBottom_toTopOf="@+id/btnRemoveCurrentNode"
+        tools:listitem="@layout/item_node"/>
+
+    <Button
+        android:id="@+id/btnRemoveCurrentNode"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Remove current node"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"/>
+
+</android.support.constraint.ConstraintLayout>

sample/src/main/res/layout/activity_second.xml

@@ -25,14 +25,14 @@
             android:layout_width="0dp"
             android:layout_height="wrap_content"
             android:layout_weight="1"
-            android:textSize="11sp"
+            android:textSize="12sp"
             android:text="Subscribe"/>
         <Button
             android:id="@+id/unsubscribe"
             android:layout_width="0dp"
             android:layout_height="wrap_content"
             android:layout_weight="1"
-            android:textSize="11sp"
+            android:textSize="12sp"
             android:text="Unsubscribe"/>
     </LinearLayout>
 </android.support.constraint.ConstraintLayout>

sample/src/main/res/layout/item_call.xml

@@ -9,5 +9,6 @@
     android:padding="16dp"
     android:background="?attr/selectableItemBackground"
     android:clickable="true"
+    android:focusable="true"
     tools:text="Sample">
 </TextView>

sample/src/main/res/layout/item_node.xml

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:paddingStart="24dp"
+    android:paddingEnd="24dp"
+    android:paddingTop="2dp"
+    android:paddingBottom="2dp">
+
+    <ImageView
+        android:id="@+id/ivNodeStatus"
+        android:layout_width="16dp"
+        android:layout_height="16dp"
+        tools:src="@drawable/ic_connected"/>
+
+    <TextView
+        android:id="@+id/tvNodeName"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="2dp"
+        android:layout_marginLeft="2dp"
+        tools:text="de.palmpayisthebestappinthefreakingworld.io/ws (123ms)"
+        android:ellipsize="middle"
+        android:singleLine="true"
+        android:textColor="#222"
+        android:textSize="16sp"/>
+
+</LinearLayout>