BAEL-1486 - sample code for JGroups. Fixed a typo in InfluxDB. (#3578)

influxdb/README.md

@@ -2,7 +2,6 @@
 
 ### Relevant Article:
 - [Introduction to using InfluxDB with Java](http://www.baeldung.com/using-influxdb-with-java/)
-- [Using InfluxDB with Java](http://www.baeldung.com/java-influxdb)
 
 ### Overview
 This Maven project contains the Java code for the article linked above.

influxdb/src/test/java/com/baeldung/influxdb/InfluxDBConnectionLiveTest.java

@@ -8,7 +8,6 @@ import org.influxdb.dto.*;
 import org.influxdb.impl.InfluxDBResultMapper;
 import org.junit.Test;
 
-import java.io.IOException;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 
@@ -103,7 +102,7 @@ public class InfluxDBConnectionLiveTest {
         // another brief pause.
         Thread.sleep(10);
 
-        List<MemoryPoint> memoryPointList = getPoints(connection, "Select * from memory", "baeldung");
+        List<com.baeldung.influxdb.MemoryPoint> memoryPointList = getPoints(connection, "Select * from memory", "baeldung");
 
         assertEquals(10, memoryPointList.size());
 

jgroups/README.md

@@ -0,0 +1,15 @@
+## Reliable Messaging with JGroups Tutorial Project
+
+### Relevant Article:
+- [Reliable Messaging with JGroups](http://www.baeldung.com/reliable-messaging-with-jgroups/)
+
+### Overview
+This Maven project contains the Java code for the article linked above.
+
+### Package Organization
+Java classes for the intro tutorial are in the org.baeldung.jgroups package.
+
+
+### Running the tests
+
+```

jgroups/pom.xml

@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>jgroups</artifactId>
+    <version>0.1-SNAPSHOT</version>
+    <packaging>jar</packaging>
+    <name>jgroups</name>
+    <description>Reliable Messaging with JGroups Tutorial</description>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.jgroups</groupId>
+            <artifactId>jgroups</artifactId>
+            <version>4.0.10.Final</version>
+        </dependency>
+
+        <dependency>
+            <groupId>commons-cli</groupId>
+            <artifactId>commons-cli</artifactId>
+            <version>1.4</version>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <java.version>1.8</java.version>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+</project>

jgroups/src/main/java/com/baeldung/jgroups/JGroupsMessenger.java

@@ -0,0 +1,222 @@
+package com.baeldung.jgroups;
+
+import org.apache.commons.cli.*;
+import org.jgroups.*;
+import org.jgroups.util.Util;
+
+import java.io.*;
+import java.util.List;
+import java.util.Optional;
+
+public class JGroupsMessenger extends ReceiverAdapter {
+
+    private JChannel channel;
+    private String userName;
+    private String clusterName;
+    private View lastView;
+    private boolean running = true;
+
+    // Our shared state
+    private Integer messageCount = 0;
+
+    /**
+     * Connect to a JGroups cluster using command line options
+     * @param args command line arguments
+     * @throws Exception
+     */
+    private void start(String[] args) throws Exception {
+        processCommandline(args);
+
+        // Create the channel
+        // This file could be moved, or made a command line option.
+        channel = new JChannel("src/main/resources/udp.xml");
+
+        // Set a name
+        channel.name(userName);
+
+        // Register for callbacks
+        channel.setReceiver(this);
+
+        // Ignore our messages
+        channel.setDiscardOwnMessages(true);
+
+        // Connect
+        channel.connect(clusterName);
+
+        // Start state transfer
+        channel.getState(null, 0);
+
+        // Do the things
+        processInput();
+
+        // Clean up
+        channel.close();
+
+    }
+
+    /**
+     * Quick and dirty implementaton of commons cli for command line args
+     * @param args the command line args
+     * @throws ParseException
+     */
+    private void processCommandline(String[] args) throws ParseException {
+
+        // Options, parser, friendly help
+        Options options = new Options();
+        CommandLineParser parser = new DefaultParser();
+        HelpFormatter formatter = new HelpFormatter();
+
+        options.addOption("u", "user", true, "User name")
+            .addOption("c", "cluster", true, "Cluster name");
+
+        CommandLine line = parser.parse(options, args);
+
+        if (line.hasOption("user")) {
+            userName = line.getOptionValue("user");
+        } else {
+            formatter.printHelp("JGroupsMessenger: need a user name.\n", options);
+            System.exit(-1);
+        }
+
+        if (line.hasOption("cluster")) {
+            clusterName = line.getOptionValue("cluster");
+        } else {
+            formatter.printHelp("JGroupsMessenger: need a cluster name.\n", options);
+            System.exit(-1);
+        }
+    }
+
+    // Start it up
+    public static void main(String[] args) throws Exception {
+        new JGroupsMessenger().start(args);
+    }
+
+
+    @Override
+    public void viewAccepted(View newView) {
+
+        // Save view if this is the first
+        if (lastView == null) {
+            System.out.println("Received initial view:");
+            newView.forEach(System.out::println);
+        } else {
+
+            // Compare to last view
+            System.out.println("Received new view.");
+
+            List<Address> newMembers = View.newMembers(lastView, newView);
+            if (newMembers.size() > 0) {
+                System.out.println("New members: ");
+                newMembers.forEach(System.out::println);
+            }
+
+            List<Address> exMembers = View.leftMembers(lastView, newView);
+            if (exMembers.size() > 0) {
+                System.out.println("Exited members:");
+                exMembers.forEach(System.out::println);
+            }
+        }
+        lastView = newView;
+    }
+
+    /**
+     * Loop on console input until we see 'x' to exit
+     */
+    private void processInput() {
+
+        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
+        while (running) {
+            try {
+
+                // Get a destination, <enter> means broadcast
+                Address destination = null;
+                System.out.print("Enter a destination: ");
+                System.out.flush();
+                String destinationName = in.readLine().toLowerCase();
+
+                if (destinationName.equals("x")) {
+                    running = false;
+                    continue;
+                } else if (!destinationName.isEmpty()) {
+                    Optional<Address> optDestination = getAddress(destinationName);
+                    if (optDestination.isPresent()) {
+                        destination = optDestination.get();
+                    } else {
+                        System.out.println("Destination not found, try again.");
+                        continue;
+                    }
+                }
+
+                // Accept a string to send
+                System.out.print("Enter a message: ");
+                System.out.flush();
+                String line = in.readLine().toLowerCase();
+                sendMessage(destination, line);
+            } catch (IOException ioe) {
+                running = false;
+            }
+        }
+        System.out.println("Exiting.");
+    }
+
+    /**
+     * Send message from here
+     * @param destination the destination
+     * @param messageString the message
+     */
+    private void sendMessage(Address destination, String messageString) {
+        try {
+            System.out.println("Sending " + messageString + " to " + destination);
+            Message message = new Message(destination, messageString);
+            channel.send(message);
+        } catch (Exception exception) {
+            System.err.println("Exception sending message: " + exception.getMessage());
+            running = false;
+        }
+    }
+
+    @Override
+    public void receive(Message message) {
+        // Print source and dest with message
+        String line = "Message received from: " + message.getSrc() + " to: " + message.getDest() + " -> " + message.getObject();
+
+        // Only track the count of broadcast messages
+        // Tracking direct message would make for a pointless state
+        if (message.getDest() == null) {
+            messageCount++;
+            System.out.println("Message count: " + messageCount);
+        }
+
+        System.out.println(line);
+    }
+
+    @Override
+    public void getState(OutputStream output) throws Exception {
+        // Serialize into the stream
+        Util.objectToStream(messageCount, new DataOutputStream(output));
+    }
+
+    @Override
+    public void setState(InputStream input) {
+
+        // NOTE: since we know that incrementing the count and transferring the state
+        // is done inside the JChannel's thread, we don't have to worry about synchronizing
+        // messageCount. For production code it should be synchronized!
+        try {
+            // Deserialize
+            messageCount = Util.objectFromStream(new DataInputStream(input));
+        } catch (Exception e) {
+            System.out.println("Error deserialing state!");
+        }
+        System.out.println(messageCount + " is the current messagecount.");
+    }
+
+
+    private Optional<Address> getAddress(String name) {
+        View view = channel.view();
+        return view.getMembers().stream().filter(address -> name.equals(address.toString())).findFirst();
+    }
+
+}
+
+

jgroups/src/main/resources/udp.xml

@@ -0,0 +1,48 @@
+<config xmlns="urn:org:jgroups"
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:schemaLocation="urn:org:jgroups http://www.jgroups.org/schema/jgroups.xsd">
+    <UDP
+         mcast_port="${jgroups.udp.mcast_port:45588}"
+         ip_ttl="4"
+         tos="8"
+         ucast_recv_buf_size="5M"
+         ucast_send_buf_size="5M"
+         mcast_recv_buf_size="5M"
+         mcast_send_buf_size="5M"
+         max_bundle_size="64K"
+         enable_diagnostics="true"
+         thread_naming_pattern="cl"
+
+         thread_pool.min_threads="0"
+         thread_pool.max_threads="20"
+         thread_pool.keep_alive_time="30000"/>
+
+    <PING />
+    <MERGE3 max_interval="30000"
+            min_interval="10000"/>
+    <FD_SOCK/>
+    <FD_ALL/>
+    <VERIFY_SUSPECT timeout="1500"  />
+    <BARRIER />
+    <pbcast.NAKACK2 xmit_interval="500"
+                    xmit_table_num_rows="100"
+                    xmit_table_msgs_per_row="2000"
+                    xmit_table_max_compaction_time="30000"
+                    use_mcast_xmit="false"
+                    discard_delivered_msgs="true"/>
+    <UNICAST3 xmit_interval="500"
+              xmit_table_num_rows="100"
+              xmit_table_msgs_per_row="2000"
+              xmit_table_max_compaction_time="60000"
+              conn_expiry_timeout="0"/>
+    <pbcast.STABLE desired_avg_gossip="50000"
+                   max_bytes="4M"/>
+    <pbcast.GMS print_local_addr="true" join_timeout="2000"/>
+    <UFC max_credits="2M"
+         min_threshold="0.4"/>
+    <MFC max_credits="2M"
+         min_threshold="0.4"/>
+    <FRAG2 frag_size="60K"  />
+    <RSVP resend_interval="2000" timeout="10000"/>
+    <pbcast.STATE_TRANSFER />
+</config>

pom.xml

@@ -93,6 +93,7 @@
         <module>javax-servlets</module>
         <module>javaxval</module>
         <module>jaxb</module>
+        <module>jgroups</module>
         <module>jee-7</module>
         <!-- <module>jhipster/jhipster-monolithic</module> -->
         <module>jjwt</module>