Simplify OpAmp client api

Author: laurit

opamp-client/README.md

@@ -12,10 +12,9 @@ client [spec](https://github.com/open-telemetry/opamp-spec/blob/main/specificati
 ```java
 // Initializing it
 
-RequestService requestService = HttpRequestService.create(OkHttpSender.create("[OPAMP_SERVICE_URL]"));
-// RequestService requestService = WebSocketRequestService.create(OkHttpWebSocket.create("[OPAMP_SERVICE_URL]")); // Use this instead to connect to the server via WebSocket.
 OpampClient client =
     OpampClient.builder()
+        .setEndpoint("[OPAMP_SERVICE_URL]")
         .putIdentifyingAttribute("service.name", "My service name")
         .enableRemoteConfig()
         .setRequestService(requestService)

opamp-client/src/main/java/io/opentelemetry/opamp/client/OpampClientBuilder.java

@@ -7,19 +7,23 @@
 
 import com.github.f4b6a3.uuid.UuidCreator;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import io.opentelemetry.opamp.client.internal.Experimental;
 import io.opentelemetry.opamp.client.internal.connectivity.http.OkHttpSender;
+import io.opentelemetry.opamp.client.internal.connectivity.websocket.OkHttpWebSocket;
 import io.opentelemetry.opamp.client.internal.impl.OpampClientImpl;
 import io.opentelemetry.opamp.client.internal.impl.OpampClientState;
 import io.opentelemetry.opamp.client.internal.request.service.HttpRequestService;
+import io.opentelemetry.opamp.client.internal.request.service.RequestService;
 import io.opentelemetry.opamp.client.internal.request.service.WebSocketRequestService;
 import io.opentelemetry.opamp.client.internal.state.State;
-import io.opentelemetry.opamp.client.request.service.RequestService;
+import java.net.URI;
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.UUID;
+import java.util.function.Function;
 import javax.annotation.Nullable;
 import opamp.proto.AgentCapabilities;
 import opamp.proto.AgentDescription;
@@ -30,27 +34,57 @@
 
 /** Builds an {@link OpampClient} instance. */
 public final class OpampClientBuilder {
+  private static final String DEFAULT_ENDPOINT_URL = "http://localhost:4320/v1/opamp";
+  private static final URI DEFAULT_ENDPOINT = URI.create(DEFAULT_ENDPOINT_URL);
+
   private final Map<String, AnyValue> identifyingAttributes = new HashMap<>();
   private final Map<String, AnyValue> nonIdentifyingAttributes = new HashMap<>();
   private long capabilities = 0;
-  private RequestService service =
-      HttpRequestService.create(OkHttpSender.create("http://localhost:4320/v1/opamp"));
+  private Function<URI, RequestService> serviceFactory =
+      endpoint -> {
+        String scheme = endpoint.getScheme();
+        if ("ws".equalsIgnoreCase(scheme) || "wss".equalsIgnoreCase(scheme)) {
+          return WebSocketRequestService.create(OkHttpWebSocket.create(endpoint.toString()));
+        } else {
+          return HttpRequestService.create(OkHttpSender.create(endpoint.toString()));
+        }
+      };
+
   @Nullable private byte[] instanceUid;
   @Nullable private State.EffectiveConfig effectiveConfigState;
+  @Nullable private URI endpoint = DEFAULT_ENDPOINT;
+
+  static {
+    Experimental.internalSetServiceFactory(
+        (builder, serviceFactory) -> builder.serviceFactory = serviceFactory);
+  }
 
   OpampClientBuilder() {}
 
   /**
-   * Sets an implementation of a {@link RequestService} to handle the request's sending process.
-   * There are 2 possible options, either {@link HttpRequestService} to use HTTP, or {@link
-   * WebSocketRequestService} to use WebSocket.
+   * Sets the OpAMP endpoint to connect to. If unset, defaults to {@value DEFAULT_ENDPOINT_URL}. The
+   * endpoint must start with either http://, https://, ws:// or wss://. Sets the address of the
+   * OpAMP Server.
+   *
+   * @param endpoint The OpAMP endpoint.
+   * @return this
+   */
+  @CanIgnoreReturnValue
+  public OpampClientBuilder setEndpoint(String endpoint) {
+    return setEndpoint(URI.create(endpoint));
+  }
+
+  /**
+   * Sets the OpAMP endpoint to connect to. If unset, defaults to {@value DEFAULT_ENDPOINT_URL}. The
+   * endpoint must start with either http://, https://, ws:// or wss://. Sets the address of the
+   * OpAMP Server.
    *
-   * @param service The request service implementation.
+   * @param endpoint The OpAMP endpoint.
    * @return this
    */
   @CanIgnoreReturnValue
-  public OpampClientBuilder setRequestService(RequestService service) {
-    this.service = service;
+  public OpampClientBuilder setEndpoint(URI endpoint) {
+    this.endpoint = endpoint;
     return this;
   }
 
@@ -402,7 +436,7 @@ public OpampClient build(OpampClient.Callbacks callbacks) {
             new State.InstanceUid(instanceUid),
             new State.Flags(0L),
             effectiveConfigState);
-    return OpampClientImpl.create(service, state, callbacks);
+    return OpampClientImpl.create(serviceFactory.apply(endpoint), state, callbacks);
   }
 
   private static State.EffectiveConfig createEffectiveConfigNoop() {

opamp-client/src/main/java/io/opentelemetry/opamp/client/internal/Experimental.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.opamp.client.internal;
+
+import io.opentelemetry.opamp.client.OpampClientBuilder;
+import io.opentelemetry.opamp.client.internal.request.service.RequestService;
+import java.net.URI;
+import java.util.function.BiConsumer;
+import java.util.function.Function;
+import javax.annotation.Nullable;
+
+/**
+ * This class is internal and experimental. Its APIs are unstable and can change at any time. Its
+ * APIs (or a version of them) may be promoted to the public stable API in the future, but no
+ * guarantees are made.
+ */
+public final class Experimental {
+
+  @Nullable
+  private static volatile BiConsumer<OpampClientBuilder, Function<URI, RequestService>>
+      setServiceFactory;
+
+  /**
+   * Sets factory function for creating {@link RequestService} instances form a given server URI.
+   */
+  public static void setServiceFactory(
+      OpampClientBuilder builder, Function<URI, RequestService> serviceFactory) {
+    if (setServiceFactory != null) {
+      setServiceFactory.accept(builder, serviceFactory);
+    }
+  }
+
+  public static void internalSetServiceFactory(
+      BiConsumer<OpampClientBuilder, Function<URI, RequestService>> setServiceFactory) {
+    Experimental.setServiceFactory = setServiceFactory;
+  }
+
+  private Experimental() {}
+}

opamp-client/src/main/java/io/opentelemetry/opamp/client/internal/impl/OpampClientImpl.java

@@ -19,12 +19,12 @@
 import io.opentelemetry.opamp.client.internal.impl.recipe.appenders.SequenceNumberAppender;
 import io.opentelemetry.opamp.client.internal.request.Field;
 import io.opentelemetry.opamp.client.internal.request.Request;
+import io.opentelemetry.opamp.client.internal.request.service.RequestService;
 import io.opentelemetry.opamp.client.internal.response.MessageData;
 import io.opentelemetry.opamp.client.internal.response.OpampServerResponseException;
 import io.opentelemetry.opamp.client.internal.response.Response;
 import io.opentelemetry.opamp.client.internal.state.ObservableState;
 import io.opentelemetry.opamp.client.internal.state.State;
-import io.opentelemetry.opamp.client.request.service.RequestService;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;

opamp-client/src/main/java/io/opentelemetry/opamp/client/internal/request/service/HttpRequestService.java

@@ -14,7 +14,6 @@
 import io.opentelemetry.opamp.client.internal.request.delay.RetryPeriodicDelay;
 import io.opentelemetry.opamp.client.internal.response.OpampServerResponseException;
 import io.opentelemetry.opamp.client.internal.response.Response;
-import io.opentelemetry.opamp.client.request.service.RequestService;
 import java.io.IOException;
 import java.time.Duration;
 import java.util.Objects;

opamp-client/src/main/java/io/opentelemetry/opamp/client/request/service/RequestService.java renamed to opamp-client/src/main/java/io/opentelemetry/opamp/client/internal/request/service/RequestService.java

@@ -3,12 +3,10 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-package io.opentelemetry.opamp.client.request.service;
+package io.opentelemetry.opamp.client.internal.request.service;
 
 import io.opentelemetry.opamp.client.OpampClient;
 import io.opentelemetry.opamp.client.internal.request.Request;
-import io.opentelemetry.opamp.client.internal.request.service.HttpRequestService;
-import io.opentelemetry.opamp.client.internal.request.service.WebSocketRequestService;
 import io.opentelemetry.opamp.client.internal.response.Response;
 import java.util.function.Supplier;
 

opamp-client/src/main/java/io/opentelemetry/opamp/client/internal/request/service/WebSocketRequestService.java

@@ -13,7 +13,6 @@
 import io.opentelemetry.opamp.client.internal.request.delay.RetryPeriodicDelay;
 import io.opentelemetry.opamp.client.internal.response.OpampServerResponseException;
 import io.opentelemetry.opamp.client.internal.response.Response;
-import io.opentelemetry.opamp.client.request.service.RequestService;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.time.Duration;

opamp-client/src/test/java/io/opentelemetry/opamp/client/internal/impl/OpampClientImplTest.java

@@ -17,9 +17,9 @@
 import io.opentelemetry.opamp.client.internal.connectivity.http.OkHttpSender;
 import io.opentelemetry.opamp.client.internal.request.Request;
 import io.opentelemetry.opamp.client.internal.request.service.HttpRequestService;
+import io.opentelemetry.opamp.client.internal.request.service.RequestService;
 import io.opentelemetry.opamp.client.internal.response.MessageData;
 import io.opentelemetry.opamp.client.internal.state.State;
-import io.opentelemetry.opamp.client.request.service.RequestService;
 import java.io.IOException;
 import java.time.Duration;
 import java.util.ArrayList;

opamp-client/src/test/java/io/opentelemetry/opamp/client/internal/request/service/HttpRequestServiceTest.java

@@ -21,7 +21,6 @@
 import io.opentelemetry.opamp.client.internal.request.Request;
 import io.opentelemetry.opamp.client.internal.request.delay.PeriodicDelay;
 import io.opentelemetry.opamp.client.internal.response.Response;
-import io.opentelemetry.opamp.client.request.service.RequestService;
 import java.io.ByteArrayInputStream;
 import java.time.Duration;
 import java.util.ArrayList;

opamp-client/src/test/java/io/opentelemetry/opamp/client/internal/request/service/WebSocketRequestServiceTest.java

@@ -23,7 +23,6 @@
 import io.opentelemetry.opamp.client.internal.request.Request;
 import io.opentelemetry.opamp.client.internal.response.OpampServerResponseException;
 import io.opentelemetry.opamp.client.internal.response.Response;
-import io.opentelemetry.opamp.client.request.service.RequestService;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.time.Duration;