Simplify example to return a Message.

This is needed to work around a2aproject/a2a-java#423
When returning Tasks via gRPC we don't actually get any artifacts

Author: kabir

examples/simple/client/pom.xml

@@ -54,6 +54,12 @@
             <groupId>com.google.guava</groupId>
             <artifactId>failureaccess</artifactId>
         </dependency>
+        <!-- SLF4J implementation for gRPC logging -->
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>2.0.17</version>
+        </dependency>
     </dependencies>
 
     <build>

examples/simple/client/src/main/java/org/wildfly/extras/a2a/examples/simple/client/SimpleExampleClient.java

@@ -11,7 +11,7 @@
 import io.a2a.client.Client;
 import io.a2a.client.ClientBuilder;
 import io.a2a.client.ClientEvent;
-import io.a2a.client.TaskEvent;
+import io.a2a.client.MessageEvent;
 import io.a2a.client.config.ClientConfig;
 import io.a2a.client.http.A2ACardResolver;
 import io.a2a.client.transport.grpc.GrpcTransport;
@@ -23,10 +23,8 @@
 import io.a2a.spec.A2AClientError;
 import io.a2a.spec.A2AClientException;
 import io.a2a.spec.AgentCard;
-import io.a2a.spec.Artifact;
 import io.a2a.spec.Message;
 import io.a2a.spec.Part;
-import io.a2a.spec.Task;
 import io.a2a.spec.TextPart;
 import io.a2a.spec.TransportProtocol;
 import io.grpc.ManagedChannelBuilder;
@@ -67,16 +65,12 @@ public String sayHello(String name) throws Exception {
 
         //CompletableFuture
         BiConsumer<ClientEvent, AgentCard> consumer = (event, agentCard) -> {
-            if (event instanceof TaskEvent taskEvent) {
-                Task task = taskEvent.getTask();
+            if (event instanceof MessageEvent messageEvent) {
+                Message msg = messageEvent.getMessage();
                 StringBuilder sb = new StringBuilder();
-                if (task.getArtifacts() != null) {
-                    for (Artifact a : task.getArtifacts()) {
-                        for (Part<?> part : a.parts()) {
-                            if (part instanceof TextPart textPart) {
-                                sb.append(textPart.getText());
-                            }
-                        }
+                for (Part<?> part : msg.getParts()) {
+                    if (part instanceof TextPart textPart) {
+                        sb.append(textPart.getText());
                     }
                 }
                 response.complete(sb.toString());

examples/simple/server/src/main/java/org/wildfly/extras/a2a/examples/simple/SimpleExampleAgentExecutorProducer.java

@@ -2,17 +2,15 @@
 
 import java.util.Collections;
 import java.util.List;
-import java.util.stream.Collectors;
 
 import jakarta.enterprise.context.ApplicationScoped;
 import jakarta.enterprise.inject.Produces;
 
 import io.a2a.server.agentexecution.AgentExecutor;
 import io.a2a.server.agentexecution.RequestContext;
 import io.a2a.server.events.EventQueue;
-import io.a2a.server.tasks.TaskUpdater;
-import io.a2a.spec.Artifact;
 import io.a2a.spec.JSONRPCError;
+import io.a2a.spec.Message;
 import io.a2a.spec.Part;
 import io.a2a.spec.TaskNotCancelableError;
 import io.a2a.spec.TextPart;
@@ -28,11 +26,6 @@ public AgentExecutor mockExecutor() {
     private static class SimpleExampleAgentExecutor implements AgentExecutor {
         @Override
         public void execute(RequestContext context, EventQueue eventQueue) throws JSONRPCError {
-            TaskUpdater updater = new TaskUpdater(context, eventQueue);
-
-            // Signal we've started working
-            updater.startWork();
-
             // Get the name sent in the user's message
             List<Part<?>> partsList = context.getMessage().getParts();
             List<TextPart> textParts = partsList.stream()
@@ -44,10 +37,13 @@ public void execute(RequestContext context, EventQueue eventQueue) throws JSONRP
             // Simulate doing work with the LLM, and adding that as an artifact.
             // In this case we just add "Hello <name>" to the list of aritfacts
             String response = "Hello " + name;
-            updater.addArtifact(Collections.singletonList(new TextPart(response)), null, "response", null);
-
-            // We have completed our simple example Task
-            updater.complete();
+            Message message = new Message.Builder()
+                    .role(Message.Role.AGENT)
+                    .parts(Collections.singletonList(new TextPart(response)))
+                    .taskId(context.getMessage().getTaskId())
+                    .contextId(context.getMessage().getContextId())
+                    .build();
+            eventQueue.enqueueEvent(message);
         }
 
         @Override