A simple Java subscribe example with jermq

examples/Java/SimpleSubscribe/pom.xml

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+<?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>
+
+  <groupId>com.example</groupId>
+  <artifactId>SimpleJavaEDDNSubscribe</artifactId>
+  <version>1.0-SNAPSHOT</version>
+
+  <name>SimpleJavaEDDNSubscribe</name>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <maven.compiler.source>1.11</maven.compiler.source>
+    <maven.compiler.target>1.11</maven.compiler.target>
+  </properties>
+
+  <dependencies>
+    <dependency> 
+      <groupId>org.zeromq</groupId>
+      <artifactId>jeromq</artifactId>
+      <version>0.5.2</version>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
+      <plugins>
+        <!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
+        <plugin>
+          <artifactId>maven-clean-plugin</artifactId>
+          <version>3.1.0</version>
+        </plugin>
+        <!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
+        <plugin>
+          <artifactId>maven-resources-plugin</artifactId>
+          <version>3.0.2</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-compiler-plugin</artifactId>
+          <version>3.8.0</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-surefire-plugin</artifactId>
+          <version>2.22.1</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-jar-plugin</artifactId>
+          <version>3.0.2</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-install-plugin</artifactId>
+          <version>2.5.2</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-deploy-plugin</artifactId>
+          <version>2.8.2</version>
+        </plugin>
+        <!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
+        <plugin>
+          <artifactId>maven-site-plugin</artifactId>
+          <version>3.7.1</version>
+        </plugin>
+        <plugin>
+          <artifactId>maven-project-info-reports-plugin</artifactId>
+          <version>3.0.0</version>
+        </plugin>
+      </plugins>
+    </pluginManagement>
+  </build>
+</project>

examples/Java/SimpleSubscribe/src/main/java/org/eddn/examples/SimpleJavaEDDNSubscribe.java

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+package org.eddn.examples;
+
+import java.util.zip.Inflater;
+
+import org.zeromq.SocketType;
+import org.zeromq.ZMQ;
+import org.zeromq.ZContext;
+
+public class SimpleJavaEDDNSubscribe {
+    private static final int MAX_MESSAGE_SIZE_KB = 200;
+    private static final String EDDN_SERVER = "tcp://eddn.edcd.io:9500";
+    private static ZContext context;
+
+    public static void main(String[] args) throws Exception {
+        context = new ZContext();    
+        String jsonMessage = getOneMessage();
+        System.out.println(jsonMessage);
+        context.close();
+    }
+
+    private static String getOneMessage() throws Exception {
+        byte[] deflatedMessage = receiveOneDeflatedMessage();
+        return inflateMessage(deflatedMessage);
+    }
+
+    private static byte[] receiveOneDeflatedMessage() {
+        ZMQ.Socket socket = getEDDNSubscriptionSocket();    
+        byte[] deflatedMessage = socket.recv();
+        return deflatedMessage;
+    }
+
+    private static ZMQ.Socket getEDDNSubscriptionSocket() {
+        ZMQ.Socket socket = context.createSocket(SocketType.SUB);
+        socket.connect(EDDN_SERVER);
+        
+        // need to subscribe to the empty topic to receive anything
+        socket.subscribe("");
+        return socket;
+    }
+
+    public static String inflateMessage(byte[] bytes) throws Exception {
+
+        Inflater decompresser = new Inflater();
+        decompresser.setInput(bytes);
+        byte[] result = new byte[MAX_MESSAGE_SIZE_KB * 1024];
+        int resultLength = decompresser.inflate(result);
+        decompresser.end();
+
+        // Decode the bytes into a String
+        String outputString = new String(result, 0, resultLength, "UTF-8");
+        return outputString;
+    }
+}