BAEL-5720 Java HttpClient Connection Management (#13452)

* BAEL-5642 Using @NotNull as a method parameter

* BAEL-5642 Add Spring Boot and bump spring and hibernate-validator versions

* BAEL-5720 Java HttpClient Connection Management

* BAEL-5720 Java HttpClient Connection Management

* BAEL-5720 move JavaHttpClient test to core-java-httpclient module

* BAEL-5720 move jetty-logging-properties to core-java-httpclient module

* BAEL-5720 add wiremock to pom

* Update pom.xml

* Delete jetty-logging.properties

---------

Co-authored-by: Loredana Crusoveanu <lore.crusoveanu@gmail.com>

core-java-modules/core-java-httpclient/pom.xml

@@ -32,6 +32,12 @@
             <version>${assertj.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.github.tomakehurst</groupId>
+            <artifactId>wiremock</artifactId>
+            <version>${wiremock.version}</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 
     <build>
@@ -53,6 +59,7 @@
         <maven.compiler.target.version>11</maven.compiler.target.version>
         <assertj.version>3.22.0</assertj.version>
         <mockserver.version>5.11.2</mockserver.version>
+        <wiremock.version>2.27.2</wiremock.version>
     </properties>
 
 </project>

core-java-modules/core-java-httpclient/src/test/java/com/baeldung/httpclient/HttpClientConnectionManagementUnitTest.java

@@ -0,0 +1,147 @@
+package com.baeldung.httpclient.conn;
+
+import com.github.tomakehurst.wiremock.WireMockServer;
+import com.github.tomakehurst.wiremock.client.WireMock;
+import com.github.tomakehurst.wiremock.core.WireMockConfiguration;
+import com.github.tomakehurst.wiremock.stubbing.ServeEvent;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.util.List;
+
+import static java.net.URI.create;
+
+
+public class HttpClientConnectionManagementUnitTest {
+
+    WireMockConfiguration firstConfiguration = WireMockConfiguration
+      .options()
+      .dynamicPort();
+    WireMockConfiguration secondConfiguration = WireMockConfiguration
+      .options()
+      .dynamicPort();
+    WireMockServer firstServer = new WireMockServer(firstConfiguration);
+    WireMockServer secondServer = new WireMockServer(secondConfiguration);
+    private String firstUrl;
+    private String secondUrl;
+
+    private HttpClient client = HttpClient.newHttpClient();
+    private HttpClient secondClient = HttpClient.newHttpClient();
+
+    private HttpRequest getRequest;
+    private HttpRequest secondGet;
+
+    @Before
+    public void setup() {
+        firstServer.start();
+        secondServer.start();
+
+        // add some request matchers
+        firstServer.stubFor(WireMock
+          .get(WireMock.anyUrl())
+          .willReturn(WireMock
+            .aResponse()
+            .withStatus(200)));
+        secondServer.stubFor(WireMock
+          .get(WireMock.anyUrl())
+          .willReturn(WireMock
+            .aResponse()
+            .withStatus(200)));
+
+        firstUrl = "http://localhost:" + firstServer.port() + "/first";
+        secondUrl = "http://localhost:" + secondServer.port() + "/second";
+
+        getRequest = HttpRequest
+          .newBuilder()
+          .uri(create(firstUrl))
+          .version(HttpClient.Version.HTTP_1_1)
+          .build();
+
+        secondGet = HttpRequest
+          .newBuilder()
+          .uri(create(secondUrl))
+          .version(HttpClient.Version.HTTP_1_1)
+          .build();
+    }
+
+    @After
+    public void tearDown() {
+        // display all the requests that the WireMock servers handled
+        List<ServeEvent> firstWiremockAllServeEvents = firstServer.getAllServeEvents();
+        List<ServeEvent> secondWiremockAllServeEvents = secondServer.getAllServeEvents();
+        firstWiremockAllServeEvents
+          .stream()
+          .map(event -> event
+            .getRequest()
+            .getAbsoluteUrl())
+          .forEach(System.out::println);
+        secondWiremockAllServeEvents
+          .stream()
+          .map(event -> event
+            .getRequest()
+            .getAbsoluteUrl())
+          .forEach(System.out::println);
+
+        // stop the WireMock servers
+        firstServer.stop();
+        secondServer.stop();
+    }
+
+    // Example 1. Use an HttpClient to connect to the same endpoint - reuses a connection from the internal pool
+    @Test
+    public final void givenAnHttpClient_whenTwoConnectionsToSameEndpointMadeSequentially_thenConnectionReused() throws InterruptedException, IOException {
+
+        // given two requests to the same destination
+        final HttpResponse<String> firstResponse = client.send(getRequest, HttpResponse.BodyHandlers.ofString());
+        final HttpResponse<String> secondResponse = client.send(getRequest, HttpResponse.BodyHandlers.ofString());
+
+        assert (firstResponse.statusCode() == 200) && (secondResponse.statusCode() == 200);
+    }
+
+    // Example 2. Use separate HttpClients to connect to the same endpoint - creates a connection per client
+    @Test
+    public final void givenTwoHttpClients_whenEachClientMakesConnectionSequentially_thenConnectionCreatedForEach() throws InterruptedException, IOException {
+
+        // given requests from two different client to same destination
+        final HttpResponse<String> firstResponse = client.send(getRequest, HttpResponse.BodyHandlers.ofString());
+        final HttpResponse<String> secondResponse = secondClient.send(getRequest, HttpResponse.BodyHandlers.ofString());
+
+        assert (firstResponse.statusCode() == 200) && (secondResponse.statusCode() == 200);
+    }
+
+    // Example 3. Use an HttpClient to Connect to first, second, then first endpoint again.
+    // New connections made each time when pool size is 1, or re-used when not restricted.
+    // Make sure to set the JVM arg when running the test:
+    // -Djdk.httpclient.connectionPoolSize=1
+    @Test
+    public final void givenAnHttpClientAndAPoolSizeOfOne_whenTwoConnectionsMadeBackToOriginal_thenFirstConnectionPurged() throws InterruptedException, IOException {
+
+        // given 3 requests, two to the first server and one to the second server
+        final HttpResponse<String> firstResponse = client.send(getRequest, HttpResponse.BodyHandlers.ofString());
+        final HttpResponse<String> secondResponse = client.send(secondGet, HttpResponse.BodyHandlers.ofString());
+        final HttpResponse<String> thirdResponse = client.send(getRequest, HttpResponse.BodyHandlers.ofString());
+
+        assert ((firstResponse.statusCode() == 200) && (secondResponse.statusCode() == 200) && (thirdResponse.statusCode() == 200));
+    }
+
+    // Example 4. Use an HttpClient to connect, wait for connection keepalive to pass, then connect again. New connection made for both calls.
+    // Make sure to set the JVM arg when running the test:
+    // -Djdk.httpclient.keepalive.timeout=2
+    @Test
+    public final void givenAnHttpClientAndConnectionKeepAliveOfTwoSeconds_whenCallMadeAfterKeepaliveExpires_thenNewConnection() throws InterruptedException, IOException {
+
+        // given 2 requests to the same destination with the second call made after the keepalive timeout has passed
+        final HttpResponse<String> firstResponse = client.send(getRequest, HttpResponse.BodyHandlers.ofString());
+        Thread.sleep(3000); // exceeds 2 seconds configured by JVM arg
+        final HttpResponse<String> secondResponse = client.send(getRequest, HttpResponse.BodyHandlers.ofString());
+
+        assert ((firstResponse.statusCode() == 200) && (secondResponse.statusCode() == 200));
+    }
+
+}
+

core-java-modules/core-java-httpclient/src/test/resources/jetty-logging.properties

@@ -0,0 +1,3 @@
+org.eclipse.jetty.util.log.class=org.eclipse.jetty.util.log.StrErrLog
+org.eclipse.jetty.LEVEL=DEBUG
+jetty.logs=logs