Finish essential parts of HTTP bridge

theodolite-benchmarks/http-bridge/build.gradle

@@ -24,7 +24,8 @@ dependencies {
   implementation project(':load-generator-commons')
   
   implementation 'io.javalin:javalin:4.3.0'
-  implementation 'org.slf4j:slf4j-simple:1.7.25'
+  implementation 'com.google.code.gson:gson:2.8.2'
+  runtimeOnly 'org.slf4j:slf4j-simple:1.7.25'
 
   testImplementation 'junit:junit:4.12'
 }

theodolite-benchmarks/http-bridge/src/main/java/theodolite/commons/httpbridge/Deserializer.java

 package theodolite.commons.httpbridge;
 
+/**
+ * A class for converting objects to strings.
+ *
+ * @param <T> Type to be deserialized from.
+ */
 @FunctionalInterface
 public interface Deserializer<T> {
 

theodolite-benchmarks/http-bridge/src/main/java/theodolite/commons/httpbridge/Endpoint.java

@@ -2,6 +2,12 @@ package theodolite.commons.httpbridge;
 
 import theodolite.commons.workloadgeneration.RecordSender;
 
+/**
+ * Class describing an endpoint of the {@link HttpBridge}, which converts JSON objects to Java
+ * objects and sends them using a {@link RecordSender}.
+ *
+ * @param <T> Type of objects this endpoint receives and converts.
+ */
 public class Endpoint<T> {
 
   private final String path;
@@ -10,6 +16,9 @@ public class Endpoint<T> {
 
   private final RecordSender<? super T> recordSender;
 
+  /**
+   * Create a new {@link Endpoint} at the given path.
+   */
   public Endpoint(
       final String path,
       final Deserializer<? extends T> recordDeserializer,
@@ -19,6 +28,9 @@ public class Endpoint<T> {
     this.recordSender = recordSender;
   }
 
+  /**
+   * Create a new {@link Endpoint} at the given path with a {@link GsonDeserializer}.
+   */
   public Endpoint(
       final String path,
       final Class<T> recordType,

theodolite-benchmarks/http-bridge/src/main/java/theodolite/commons/httpbridge/EnvVarHttpBridgeFactory.java

+package theodolite.commons.httpbridge;
+
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+import theodolite.commons.workloadgeneration.ConfigurationKeys;
+import theodolite.commons.workloadgeneration.TitanKafkaSenderFactory;
+import titan.ccp.model.records.ActivePowerRecord;
+
+class EnvVarHttpBridgeFactory {
+
+  private static final String PORT_KEY = "PORT";
+  private static final int PORT_DEFAULT = 8080;
+
+  private static final String HOST_KEY = "HOST";
+  private static final String HOST_DEFAULT = "0.0.0.0"; // NOPMD
+
+  private static final String KAFKA_BOOTSTRAP_SERVERS_DEFAULT = "localhost:9092"; // NOPMD
+  private static final String KAFKA_TOPIC_DEFAULT = "input";
+  private static final String SCHEMA_REGISTRY_URL_DEFAULT = "http://localhost:8081";
+
+  public HttpBridge create() {
+    final Endpoint<?> converter = new Endpoint<>(
+        "/",
+        ActivePowerRecord.class,
+        TitanKafkaSenderFactory.forKafkaConfig(
+            this.getKafkaBootstrapServer(),
+            this.getKafkaTopic(),
+            this.getSchemaRegistryUrl()));
+    return new HttpBridge(this.getHost(), this.getPort(), List.of(converter));
+  }
+
+  private String getHost() {
+    return Objects.requireNonNullElse(System.getenv(HOST_KEY), HOST_DEFAULT);
+  }
+
+  private int getPort() {
+    return Optional.ofNullable(System.getenv(PORT_KEY)).map(Integer::parseInt).orElse(PORT_DEFAULT);
+  }
+
+  private String getKafkaBootstrapServer() {
+    return Objects.requireNonNullElse(
+        System.getenv(ConfigurationKeys.KAFKA_BOOTSTRAP_SERVERS),
+        KAFKA_BOOTSTRAP_SERVERS_DEFAULT);
+  }
+
+  private String getKafkaTopic() {
+    return Objects.requireNonNullElse(
+        System.getenv(ConfigurationKeys.KAFKA_INPUT_TOPIC),
+        KAFKA_TOPIC_DEFAULT);
+  }
+
+  private String getSchemaRegistryUrl() {
+    return Objects.requireNonNullElse(
+        System.getenv(ConfigurationKeys.SCHEMA_REGISTRY_URL),
+        SCHEMA_REGISTRY_URL_DEFAULT);
+  }
+
+}

theodolite-benchmarks/http-bridge/src/main/java/theodolite/commons/httpbridge/GsonDeserializer.java

@@ -2,6 +2,11 @@ package theodolite.commons.httpbridge;
 
 import com.google.gson.Gson;
 
+/**
+ * A {@link Deserializer} based on GSON.
+ *
+ * @param <T> Type to be serialized from.
+ */
 public class GsonDeserializer<T> implements Deserializer<T> {
 
   private final Gson gson;

theodolite-benchmarks/http-bridge/src/main/java/theodolite/commons/httpbridge/HttpBridge.java

 package theodolite.commons.httpbridge;
 
 import java.util.List;
-import theodolite.commons.workloadgeneration.TitanKafkaSenderFactory;
-import titan.ccp.model.records.ActivePowerRecord;
+import theodolite.commons.workloadgeneration.RecordSender;
 
+/**
+ * Class that creates a webserver with potentially multiple {@link Endpoint}s, which receives JSON
+ * objects at these endpoints, converts them to Java objects and send them using
+ * {@link RecordSender}s.
+ */
 public class HttpBridge {
 
-  private static final int PORT = 8080;
-  private static final String HOST = "0.0.0.0"; // NOPMD
+  private final JavalinWebServer webServer;
 
-  public void run() {
-    final Endpoint<?> converter = new Endpoint<>(
-        "/",
-        ActivePowerRecord.class,
-        TitanKafkaSenderFactory.forKafkaConfig(null, null, null));
+  public HttpBridge(final String host, final int port, final List<Endpoint<?>> converters) {
+    this.webServer = new JavalinWebServer(converters, host, port);
+  }
+
+  public void start() {
+    this.webServer.start();
+  }
+
+  public void stop() {
+    this.webServer.stop();
+  }
+
+  public void runAsStandalone() {
+    Runtime.getRuntime().addShutdownHook(new Thread(() -> this.stop()));
+    this.start();
+  }
+
+  public static HttpBridge fromEnvironment() {
+    return new EnvVarHttpBridgeFactory().create();
+  }
 
-    final JavalinWebServer webServer = new JavalinWebServer(List.of(converter), HOST, PORT);
-    webServer.start();
+  public static void main(final String[] args) {
+    HttpBridge.fromEnvironment().runAsStandalone();
   }
 
 }

theodolite-benchmarks/http-bridge/src/main/java/theodolite/commons/httpbridge/JavalinWebServer.java

@@ -3,6 +3,9 @@ package theodolite.commons.httpbridge;
 import io.javalin.Javalin;
 import java.util.Collection;
 
+/**
+ * Implementation of a webserver based on the Javalin framework.
+ */
 public class JavalinWebServer {
 
   private static final int HTTP_SUCCESS = 200;
@@ -12,6 +15,9 @@ public class JavalinWebServer {
   private final String host;
   private final int port;
 
+  /**
+   * Create a new instance, running on the specified host and port with the configured endpoints.
+   */
   public JavalinWebServer(
       final Collection<Endpoint<?>> converters,
       final String host,