Simple HTTP Server and Client

README.md

+# Network Communication
+## Simple HTTP Server and Client
+
+*Some useful links*
+* [HttpServer Class](https://docs.oracle.com/javase/8/docs/jre/api/net/httpserver/spec/com/sun/net/httpserver/HttpServer.html)
+* [HttpClient Class](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpClient.html)
+* [HttpRequest Class](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.http/java/net/http/HttpRequest.html)

httpclient/.gitignore

+target/
+!.mvn/wrapper/maven-wrapper.jar
+!**/src/main/**/target/
+!**/src/test/**/target/
+
+### IntelliJ IDEA ###
+.idea/modules.xml
+.idea/jarRepositories.xml
+.idea/compiler.xml
+.idea/libraries/
+*.iws
+*.iml
+*.ipr
+
+### Eclipse ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/
+build/
+!**/src/main/**/build/
+!**/src/test/**/build/
+
+### VS Code ###
+.vscode/
+
+### Mac OS ###
+.DS_Store
\ No newline at end of file

httpclient/pom.xml

+<?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>org.example</groupId>
+    <artifactId>httpclient</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <properties>
+        <maven.compiler.source>17</maven.compiler.source>
+        <maven.compiler.target>17</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+</project>
\ No newline at end of file

httpclient/src/main/java/Aggregator.java

+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+
+public class Aggregator {
+
+    private WebClient webClient;
+
+    public Aggregator() {
+        this.webClient = new WebClient();
+    }
+
+    /*send task to list of workers*/
+    public List<String> sendTasksToWorkers(List<String> workersAddresses, List<String> tasks) {
+       /*
+       Add your code here
+        */
+        throw new UnsupportedOperationException();
+    }
+
+    /*send task to list of workers*/
+    public List<String> sendTasksToWorkers(List<String> workersAddresses, List<String> tasks, String headers) {
+       /*
+       Add your code here
+        */
+        throw new UnsupportedOperationException();
+    }
+}

httpclient/src/main/java/Application.java

+import java.util.Arrays;
+import java.util.List;
+
+public class Application {
+    private static final String WORKER_ADDRESS_1 = "http://localhost:8080/task";
+    private static final String WORKER_ADDRESS_2 = "http://localhost:8081/task";
+
+    public static void main(String[] args) {
+
+        Aggregator aggregator = new Aggregator();
+        String task1 = "10,200";
+        String task2 = "123456789,100000000000000,700000002342343";
+
+        String headers = "X-Debug: true";
+
+        List<String> results = aggregator.sendTasksToWorkers(Arrays.asList(WORKER_ADDRESS_1, WORKER_ADDRESS_2),
+                Arrays.asList(task1, task2));
+
+        for (String result : results) {
+            System.out.println(result);
+        }
+
+        List<String> resultsWithHeaders = aggregator.sendTasksToWorkers(Arrays.asList(WORKER_ADDRESS_1, WORKER_ADDRESS_2),
+                Arrays.asList(task1, task2), headers);
+
+        for (String result : resultsWithHeaders) {
+            System.out.println(result);
+        }
+    }
+}

httpclient/src/main/java/WebClient.java

+import java.net.http.HttpClient;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+
+public class WebClient {
+
+    private HttpClient client;
+
+    /* instantiate web client */
+    /* Read more about Builder pattern https://en.wikipedia.org/wiki/Builder_pattern*/
+    public WebClient() {
+        this.client = HttpClient.newBuilder().version(HttpClient.Version.HTTP_2).build();
+    }
+
+    /* send task (post http request) asynchronously */
+    public CompletableFuture<String> sendTask(String url, byte[] requestPayload) {
+    /*
+    Add your code here
+     */
+        throw new UnsupportedOperationException();
+    }
+
+    /* send task (post http request) asynchronously with custom headers*/
+    public CompletableFuture<String> sendTask(String url, byte[] requestPayload, String headers) {
+    /*
+    Add your code here
+     */
+        throw new UnsupportedOperationException();
+    }
+}

httpserver/pom.xml

+<?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>org.example</groupId>
+    <artifactId>httpserver</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>9</source>
+                    <target>9</target>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+
+</project>
\ No newline at end of file

httpserver/src/main/java/WebServer.java

+import com.sun.net.httpserver.*;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.math.BigInteger;
+import java.net.InetSocketAddress;
+import java.util.Arrays;
+import java.util.concurrent.Executors;
+import java.util.logging.Logger;
+
+public class WebServer {
+    static final Logger logger = Logger.getLogger("WebServer");
+    private static final String TASK_ENDPOINT = "/task";
+    private static final String Status_ENDPOINT = "/status";
+    private final int port;
+    private HttpServer server;
+
+    public WebServer(int port) {
+        this.port = port;
+    }
+
+    public static void main(String[] args) {
+        int serverPort = 8080;
+        if (args.length == 1) {
+            serverPort = Integer.parseInt(args[0]);
+        }
+
+        WebServer webServer = new WebServer(serverPort);
+        webServer.startServer();
+
+        System.out.println("Server is listening on port " + serverPort);
+    }
+
+    public void startServer() {
+        try {
+            this.server = HttpServer.create(new InetSocketAddress(port), 0);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+
+        HttpContext statusContext = server.createContext(Status_ENDPOINT);
+        HttpContext taskContext = server.createContext(TASK_ENDPOINT);
+
+        statusContext.setHandler(this::handleStatusCheckRequest);
+        taskContext.setHandler(this::handleTaskRequest);
+
+        server.setExecutor(Executors.newFixedThreadPool(8));
+        server.start();
+
+    }
+
+    private void handleTaskRequest(HttpExchange exchange) throws IOException {
+        if (!exchange.getRequestMethod().equalsIgnoreCase("post")) {
+            exchange.close();
+            return;
+        }
+
+        Headers headers = exchange.getRequestHeaders();
+        if (headers.containsKey("X-Test") && headers.get("X-Test").get(0).equalsIgnoreCase("true")) {
+            String dummyResp = "123\n";
+            sendResponse(dummyResp.getBytes(), exchange);
+            return;
+        }
+
+        boolean isDebugMode = false;
+        if (headers.containsKey("X-Debug") && headers.get("X-Debug").get(0).equalsIgnoreCase("true")) {
+            isDebugMode = true;
+        }
+        long startTime = System.nanoTime();
+
+        byte[] requestBytes = exchange.getRequestBody().readAllBytes();
+        byte[] responseBytes = calculateResponse(requestBytes);
+
+        long finishTime = System.nanoTime();
+
+        if (isDebugMode) {
+            String debugMessage = String.format("Operation took %d ns", finishTime - startTime);
+            exchange.getResponseHeaders().put("X-Debug-Info", Arrays.asList(debugMessage));
+        }
+
+        sendResponse(responseBytes, exchange);
+
+    }
+
+    private byte[] calculateResponse(byte[] requestBytes) {
+        String bodyString = new String(requestBytes);
+        String[] stringNumbers = bodyString.split(",");
+
+        BigInteger result = BigInteger.ONE;
+
+        for (String number : stringNumbers) {
+            BigInteger bigInteger = new BigInteger(number);
+            result = result.multiply(bigInteger);
+        }
+
+        return String.format("Result of the multiplication is %s\n", result).getBytes();
+    }
+
+    private void handleStatusCheckRequest(HttpExchange exchange) throws IOException {
+        if (!exchange.getRequestMethod().equalsIgnoreCase("get")) {
+            exchange.close();
+            return;
+        }
+        String responseMessage = "Server is alive\n";
+        sendResponse(responseMessage.getBytes(), exchange);
+
+    }
+
+    private void sendResponse(byte[] responseBytes, HttpExchange exchange) throws IOException {
+        exchange.sendResponseHeaders(200, responseBytes.length);
+        OutputStream outputStream = exchange.getResponseBody();
+        outputStream.write(responseBytes);
+        outputStream.flush();
+        outputStream.close();
+        exchange.close();
+    }
+
+}