Adding the client side integration of otel

Signed-off-by: Emmanuel Hugonnet <[email protected]>

Author: ehsavoie

client/base/src/main/java/io/a2a/client/ClientBuilder.java

@@ -9,6 +9,7 @@
 import io.a2a.spec.AgentCard;
 import io.a2a.spec.AgentInterface;
 import io.a2a.spec.TransportProtocol;
+import java.lang.reflect.InvocationTargetException;
 
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -37,7 +38,8 @@ public class ClientBuilder {
     private final AgentCard agentCard;
 
     private final List<BiConsumer<ClientEvent, AgentCard>> consumers = new ArrayList<>();
-    private @Nullable Consumer<Throwable> streamErrorHandler;
+    private @Nullable
+    Consumer<Throwable> streamErrorHandler;
     private ClientConfig clientConfig = new ClientConfig.Builder().build();
 
     private final Map<Class<? extends ClientTransport>, ClientTransportConfig<? extends ClientTransport>> clientTransports = new LinkedHashMap<>();
@@ -105,7 +107,7 @@ private ClientTransport buildClientTransport() throws A2AClientException {
             throw new A2AClientException("Missing required TransportConfig for " + agentInterface.transport());
         }
 
-        return clientTransportProvider.create(clientTransportConfig, agentCard, agentInterface.url());
+        return wrap(clientTransportProvider.create(clientTransportConfig, agentCard, agentInterface.url()), clientTransportConfig);
     }
 
     private Map<String, String> getServerPreferredTransports() {
@@ -160,10 +162,23 @@ private AgentInterface findBestClientTransport() throws A2AClientException {
         if (transportProtocol == null || transportUrl == null) {
             throw new A2AClientException("No compatible transport found");
         }
-        if (! transportProviderRegistry.containsKey(transportProtocol)) {
+        if (!transportProviderRegistry.containsKey(transportProtocol)) {
             throw new A2AClientException("No client available for " + transportProtocol);
         }
 
         return new AgentInterface(transportProtocol, transportUrl);
     }
+
+    private ClientTransport wrap(ClientTransport transport, ClientTransportConfig<? extends ClientTransport> clientTransportConfig) {
+        try {
+            Class<?> factoryClass = this.getClass().getClassLoader().loadClass("io.a2a.extras.opentelemetry.OpenTelemetryClientTransportFactory");
+            Object openTelemetryClientTransportFactory = factoryClass.getConstructor(new Class<?>[0]).newInstance(new Object[0]);
+            factoryClass.getDeclaredMethod("config", ClientTransportConfig.class).invoke(openTelemetryClientTransportFactory, clientTransportConfig);
+            return (ClientTransport) factoryClass.getDeclaredMethod("wrap", ClientTransport.class).invoke(openTelemetryClientTransportFactory, transport);
+        } catch (ClassNotFoundException ex) {
+
+        } catch (NoSuchMethodException | InstantiationException | IllegalAccessException | IllegalArgumentException | InvocationTargetException ex) {
+        }
+        return transport;
+    }
 }

client/transport/rest/src/main/java/io/a2a/client/transport/rest/RestTransportConfig.java

@@ -4,7 +4,7 @@
 import io.a2a.client.transport.spi.ClientTransportConfig;
 import org.jspecify.annotations.Nullable;
 
-public class RestTransportConfig extends ClientTransportConfig<RestTransport>  {
+public class RestTransportConfig extends ClientTransportConfig<RestTransport> {
 
     private final @Nullable A2AHttpClient httpClient;
 

client/transport/spi/src/main/java/io/a2a/client/transport/spi/ClientTransportConfig.java

@@ -2,15 +2,18 @@
 
 import io.a2a.client.transport.spi.interceptors.ClientCallInterceptor;
 import java.util.ArrayList;
+import java.util.HashMap;
 
 import java.util.List;
+import java.util.Map;
 
 /**
  * Configuration for an A2A client transport.
  */
 public abstract class ClientTransportConfig<T extends ClientTransport> {
 
     protected List<ClientCallInterceptor> interceptors = new ArrayList<>();
+    protected Map<String, ? extends Object > parameters = new HashMap<>();
 
     public void setInterceptors(List<ClientCallInterceptor> interceptors) {
         this.interceptors = new ArrayList<>(interceptors);
@@ -19,4 +22,12 @@ public void setInterceptors(List<ClientCallInterceptor> interceptors) {
     public List<ClientCallInterceptor> getInterceptors() {
         return interceptors;
     }
+
+    public void setParameters(Map<String, ? extends Object > parameters) {
+        this.parameters = new HashMap<>(parameters);
+    }
+
+    public Map<String, ? extends Object > getParameters() {
+        return parameters;
+    }
 }

examples/helloworld/client/pom.xml

@@ -20,6 +20,22 @@
             <groupId>io.github.a2asdk</groupId>
             <artifactId>a2a-java-sdk-client</artifactId>
         </dependency>
+        <dependency>
+            <groupId>io.github.a2asdk</groupId>
+            <artifactId>a2a-java-sdk-opentelemetry</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.opentelemetry</groupId>
+            <artifactId>opentelemetry-sdk</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.opentelemetry</groupId>
+            <artifactId>opentelemetry-exporter-otlp</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.opentelemetry</groupId>
+            <artifactId>opentelemetry-exporter-logging</artifactId>
+        </dependency>
     </dependencies>
 
     <build>

examples/helloworld/client/src/main/java/io/a2a/examples/helloworld/HelloWorldClient.java

@@ -12,7 +12,6 @@
 import io.a2a.A2A;
 
 import io.a2a.client.Client;
-import io.a2a.client.ClientBuilder;
 import io.a2a.client.ClientEvent;
 import io.a2a.client.MessageEvent;
 import io.a2a.client.http.A2ACardResolver;
@@ -22,6 +21,11 @@
 import io.a2a.spec.Message;
 import io.a2a.spec.Part;
 import io.a2a.spec.TextPart;
+import io.opentelemetry.api.OpenTelemetry;
+import io.opentelemetry.exporter.otlp.trace.OtlpGrpcSpanExporter;
+import io.opentelemetry.sdk.OpenTelemetrySdk;
+import io.opentelemetry.sdk.trace.SdkTracerProvider;
+import io.opentelemetry.sdk.trace.export.SimpleSpanProcessor;
 
 /**
  * A simple example of using the A2A Java SDK to communicate with an A2A server.
@@ -35,6 +39,7 @@ public class HelloWorldClient {
 
     public static void main(String[] args) {
         try {
+            OpenTelemetry openTelemetrySdk = initOpenTelemetry();
             AgentCard finalAgentCard = null;
             AgentCard publicAgentCard = new A2ACardResolver("http://localhost:9999").getAgentCard();
             System.out.println("Successfully fetched public agent card:");
@@ -82,16 +87,18 @@ public static void main(String[] args) {
                 error.printStackTrace();
                 messageResponse.completeExceptionally(error);
             };
-
+            JSONRPCTransportConfig transportConfig = new JSONRPCTransportConfig();
+            transportConfig.setParameters(Map.of("io.a2a.extras.opentelemetry.Tracer",
+                    openTelemetrySdk.getTracer("helloworld-client")));
             Client client = Client
                     .builder(finalAgentCard)
                     .addConsumers(consumers)
                     .streamingErrorHandler(streamingErrorHandler)
-                    .withTransport(JSONRPCTransport.class, new JSONRPCTransportConfig())
+                    .withTransport(JSONRPCTransport.class, transportConfig)
                     .build();
 
             Message message = A2A.toUserMessage(MESSAGE_TEXT); // the message ID will be automatically generated for you
-            
+
             System.out.println("Sending message: " + MESSAGE_TEXT);
             client.sendMessage(message);
             System.out.println("Message sent successfully. Responses will be handled by the configured consumers.");
@@ -108,4 +115,16 @@ public static void main(String[] args) {
         }
     }
 
-} 
+    static OpenTelemetry initOpenTelemetry() {
+        SdkTracerProvider sdkTracerProvider = SdkTracerProvider.builder()
+                .addSpanProcessor(SimpleSpanProcessor.create(OtlpGrpcSpanExporter.getDefault()))
+                .build();
+
+        OpenTelemetrySdk openTelemetrySdk = OpenTelemetrySdk.builder()
+                .setTracerProvider(sdkTracerProvider)
+                .build();
+
+        Runtime.getRuntime().addShutdownHook(new Thread(sdkTracerProvider::close));
+        return openTelemetrySdk;
+    }
+}

examples/helloworld/pom.xml

@@ -34,25 +34,6 @@
         </dependencies>
     </dependencyManagement>
 
-    <build>
-        <plugins>
-            <plugin>
-                <groupId>io.quarkus</groupId>
-                <artifactId>quarkus-maven-plugin</artifactId>
-                <extensions>true</extensions>
-                <executions>
-                    <execution>
-                        <goals>
-                            <goal>build</goal>
-                            <goal>generate-code</goal>
-                            <goal>generate-code-tests</goal>
-                        </goals>
-                    </execution>
-                </executions>
-            </plugin>
-        </plugins>
-    </build>
-
     <modules>
         <module>client</module>
         <module>server</module>

examples/helloworld/server/pom.xml

@@ -37,7 +37,6 @@
         <dependency>
             <groupId>io.github.a2asdk</groupId>
             <artifactId>a2a-java-sdk-opentelemetry</artifactId>
-            <version>0.4.0.Alpha1-SNAPSHOT</version>
         </dependency>
         <dependency>
             <groupId>jakarta.enterprise</groupId>