feat(examples): serve an extended agent card in helloworld

examples/helloworld/client/README.md

@@ -152,8 +152,8 @@ jbang examples/helloworld/client/src/main/java/org/a2aproject/sdk/examples/hello
 The Java client (`HelloWorldClient.java`) performs the following actions:
 
 1. Fetches the server's public agent card
-2. Fetches the server's extended agent card
-3. Creates a client using the extended agent card that connects to the Python server at `http://localhost:9999`.
+2. Creates a client from it that connects to the Python server at `http://localhost:9999`.
+3. Fetches the server's extended agent card through the client, if the public card advertises one. The client uses it from then on.
 4. Sends a regular message asking "how much is 10 USD in INR?".
 5. Prints the server's response.
 6. Sends the same message as a streaming request.

examples/helloworld/client/src/main/java/org/a2aproject/sdk/examples/helloworld/client/HelloWorldClient.java

@@ -60,21 +60,6 @@ public static void main(String[] args) {
             AgentCard publicAgentCard = A2ACardResolver.builder().baseUrl(SERVER_URL).build().getAgentCard();
             System.out.println("Successfully fetched public agent card:");
             System.out.println(JsonUtil.toJson(publicAgentCard));
-            System.out.println("Using public agent card for client initialization (default).");
-            AgentCard finalAgentCard = publicAgentCard;
-
-            if (publicAgentCard.capabilities().extendedAgentCard()) {
-                System.out.println("Public card supports authenticated extended card. Attempting to fetch from: " + SERVER_URL + "/ExtendedAgentCard");
-                Map<String, String> authHeaders = new HashMap<>();
-                authHeaders.put("Authorization", "Bearer dummy-token-for-extended-card");
-                AgentCard extendedAgentCard = A2A.getAgentCard(SERVER_URL, "/ExtendedAgentCard", authHeaders);
-                System.out.println("Successfully fetched authenticated extended agent card:");
-                System.out.println(JsonUtil.toJson(extendedAgentCard));
-                System.out.println("Using AUTHENTICATED EXTENDED agent card for client initialization.");
-                finalAgentCard = extendedAgentCard;
-            } else {
-                System.out.println("Public card does not indicate support for an extended card. Using public card.");
-            }
 
             final CompletableFuture<String> messageResponse = new CompletableFuture<>();
 
@@ -109,12 +94,21 @@ public static void main(String[] args) {
             }
 
             ClientBuilder clientBuilder = Client
-                    .builder(finalAgentCard)
+                    .builder(publicAgentCard)
                     .addConsumers(consumers)
                     .streamingErrorHandler(streamingErrorHandler);
             configureTransport(clientBuilder, openTelemetrySdk);
              Client client = clientBuilder.build();
 
+            if (publicAgentCard.capabilities().extendedAgentCard()) {
+                // The client uses the extended card for the calls that follow
+                AgentCard extendedAgentCard = client.getExtendedAgentCard();
+                System.out.println("Successfully fetched extended agent card:");
+                System.out.println(JsonUtil.toJson(extendedAgentCard));
+            } else {
+                System.out.println("Public card does not indicate support for an extended card. Using public card.");
+            }
+
             Message message = A2A.toUserMessage(MESSAGE_TEXT); // the message ID will be automatically generated for you
             try {
                 System.out.println("Sending message: " + MESSAGE_TEXT);

examples/helloworld/server/README.md

@@ -83,8 +83,8 @@ The client will connect to the Java server running on `http://localhost:9999`.
 The Python A2A client (`test_client.py`) performs the following actions:
 
 1. Fetches the server's public agent card
-2. Fetches the server's extended agent card if supported by the server (see https://github.com/a2aproject/a2a-java/issues/81)
-3. Creates an A2A client using the extended agent card that connects to the Python server at `http://localhost:9999`.
+2. Fetches the server's extended agent card
+3. Creates an A2A client using the extended agent card that connects to the Java server at `http://localhost:9999`.
 4. Sends a regular message asking "how much is 10 USD in INR?".
 5. Prints the server's response.
 6. Sends the same message as a streaming request.

examples/helloworld/server/src/main/java/org/a2aproject/sdk/examples/helloworld/server/AgentCardProducer.java

@@ -1,5 +1,6 @@
 package org.a2aproject.sdk.examples.helloworld.server;
 
+import org.a2aproject.sdk.server.ExtendedAgentCard;
 import org.a2aproject.sdk.server.PublicAgentCard;
 import org.a2aproject.sdk.spec.AgentCapabilities;
 import org.a2aproject.sdk.spec.AgentCard;
@@ -10,6 +11,7 @@
 import jakarta.enterprise.inject.Produces;
 import org.eclipse.microprofile.config.inject.ConfigProperty;
 
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
@@ -34,6 +36,7 @@ public AgentCard agentCard() {
                 .capabilities(AgentCapabilities.builder()
                         .streaming(true)
                         .pushNotifications(true)
+                        .extendedAgentCard(true)
                         .build())
                 .defaultInputModes(Collections.singletonList("text"))
                 .defaultOutputModes(Collections.singletonList("text"))
@@ -47,6 +50,26 @@ public AgentCard agentCard() {
                 .build();
     }
 
+    // Returned by GetExtendedAgentCard. No authentication is configured here, so any client can read it.
+    @Produces
+    @ExtendedAgentCard
+    public AgentCard extendedAgentCard() {
+        AgentCard publicCard = agentCard();
+        List<AgentSkill> skills = new ArrayList<>(publicCard.skills());
+        skills.add(AgentSkill.builder()
+                .id("super_hello_world")
+                .name("Returns a SUPER hello world")
+                .description("A more enthusiastic hello world, only listed in the extended agent card")
+                .tags(List.of("hello world", "extended"))
+                .examples(List.of("super hi", "give me a super hello"))
+                .build());
+        return AgentCard.builder(publicCard)
+                .name("Hello World Agent - Extended Edition")
+                .description("The full-featured hello world agent for authenticated users")
+                .skills(skills)
+                .build();
+    }
+
     private AgentInterface getAgentInterface() {
         TransportProtocol protocol = TransportProtocol.fromString(protocolStr);
         String url = switch (protocol) {