feat: Support multiple payload types in push notifications

extras/push-notification-config-store-database-jpa/src/test/java/io/a2a/extras/pushnotificationconfigstore/database/jpa/JpaDatabasePushNotificationConfigStoreIntegrationTest.java

@@ -88,7 +88,7 @@ public void testDirectNotificationTrigger() {
         mockPushNotificationSender.sendNotification(testTask);
 
         // Verify it was captured
-        Queue<Task> captured = mockPushNotificationSender.getCapturedTasks();
+        Queue<Task> captured = mockPushNotificationSender.getCapturedEvents();
         assertEquals(1, captured.size());
         assertEquals("direct-test-task", captured.peek().getId());
     }
@@ -151,7 +151,7 @@ public void testJpaDatabasePushNotificationConfigStoreIntegration() throws Excep
         boolean notificationReceived = false;
 
         while (System.currentTimeMillis() < end) {
-            if (!mockPushNotificationSender.getCapturedTasks().isEmpty()) {
+            if (!mockPushNotificationSender.getCapturedEvents().isEmpty()) {
                 notificationReceived = true;
                 break;
             }
@@ -161,7 +161,7 @@ public void testJpaDatabasePushNotificationConfigStoreIntegration() throws Excep
         assertTrue(notificationReceived, "Timeout waiting for push notification.");
 
         // Step 6: Verify the captured notification
-        Queue<Task> capturedTasks = mockPushNotificationSender.getCapturedTasks();
+        Queue<Task> capturedTasks = mockPushNotificationSender.getCapturedEvents();
 
         // Verify the notification contains the correct task with artifacts
         Task notifiedTaskWithArtifact = capturedTasks.stream()

extras/push-notification-config-store-database-jpa/src/test/java/io/a2a/extras/pushnotificationconfigstore/database/jpa/MockPushNotificationSender.java

@@ -3,12 +3,12 @@
 import java.util.Queue;
 import java.util.concurrent.ConcurrentLinkedQueue;
 
+import io.a2a.spec.StreamingEventKind;
 import jakarta.annotation.Priority;
 import jakarta.enterprise.context.ApplicationScoped;
 import jakarta.enterprise.inject.Alternative;
 
 import io.a2a.server.tasks.PushNotificationSender;
-import io.a2a.spec.Task;
 
 /**
  * Mock implementation of PushNotificationSender for integration testing.
@@ -19,18 +19,18 @@
 @Priority(100)
 public class MockPushNotificationSender implements PushNotificationSender {
 
-    private final Queue<Task> capturedTasks = new ConcurrentLinkedQueue<>();
+    private final Queue<StreamingEventKind> capturedEvents = new ConcurrentLinkedQueue<>();
 
     @Override
-    public void sendNotification(Task task) {
-        capturedTasks.add(task);
+    public void sendNotification(StreamingEventKind kind) {
+        capturedEvents.add(kind);
     }
 
-    public Queue<Task> getCapturedTasks() {
-        return capturedTasks;
+    public Queue<StreamingEventKind> getCapturedEvents() {
+        return capturedEvents;
     }
 
     public void clear() {
-        capturedTasks.clear();
+        capturedEvents.clear();
     }
 }

server-common/src/main/java/io/a2a/server/tasks/BasePushNotificationSender.java

@@ -3,6 +3,15 @@
 import static io.a2a.client.http.A2AHttpClient.APPLICATION_JSON;
 import static io.a2a.client.http.A2AHttpClient.CONTENT_TYPE;
 import static io.a2a.common.A2AHeaders.X_A2A_NOTIFICATION_TOKEN;
+import static io.a2a.spec.Message.MESSAGE;
+import static io.a2a.spec.Task.TASK;
+import static io.a2a.spec.TaskArtifactUpdateEvent.ARTIFACT_UPDATE;
+import static io.a2a.spec.TaskStatusUpdateEvent.STATUS_UPDATE;
+
+import io.a2a.spec.Message;
+import io.a2a.spec.StreamingEventKind;
+import io.a2a.spec.TaskArtifactUpdateEvent;
+import io.a2a.spec.TaskStatusUpdateEvent;
 import jakarta.enterprise.context.ApplicationScoped;
 import jakarta.inject.Inject;
 
@@ -42,34 +51,45 @@ public BasePushNotificationSender(PushNotificationConfigStore configStore, A2AHt
     }
 
     @Override
-    public void sendNotification(Task task) {
-        List<PushNotificationConfig> pushConfigs = configStore.getInfo(task.getId());
+    public void sendNotification(StreamingEventKind kind) {
+        String taskId = switch (kind.getKind()) {
+            case TASK -> ((Task) kind).getId();
+            case MESSAGE -> ((Message)kind).getTaskId();
+            case STATUS_UPDATE -> ((TaskStatusUpdateEvent)kind).getTaskId();
+            case ARTIFACT_UPDATE -> ((TaskArtifactUpdateEvent)kind).getTaskId();
+            default -> null;
+        };
+        if (taskId == null) {
+           return;
+        }
+
+        List<PushNotificationConfig> pushConfigs = configStore.getInfo(taskId);
         if (pushConfigs == null || pushConfigs.isEmpty()) {
             return;
         }
 
         List<CompletableFuture<Boolean>> dispatchResults = pushConfigs
                 .stream()
-                .map(pushConfig -> dispatch(task, pushConfig))
+                .map(pushConfig -> dispatch(kind, pushConfig))
                 .toList();
         CompletableFuture<Void> allFutures = CompletableFuture.allOf(dispatchResults.toArray(new CompletableFuture[0]));
         CompletableFuture<Boolean> dispatchResult = allFutures.thenApply(v -> dispatchResults.stream()
                 .allMatch(CompletableFuture::join));
         try {
             boolean allSent = dispatchResult.get();
-            if (! allSent) {
-                LOGGER.warn("Some push notifications failed to send for taskId: " + task.getId());
+            if (!allSent) {
+                LOGGER.warn("Some push notifications failed to send for taskId: " + taskId);
             }
         } catch (InterruptedException | ExecutionException e) {
-            LOGGER.warn("Some push notifications failed to send for taskId " + task.getId() + ": {}", e.getMessage(), e);
+            LOGGER.warn("Some push notifications failed to send for taskId " + taskId + ": {}", e.getMessage(), e);
         }
     }
 
-    private CompletableFuture<Boolean> dispatch(Task task, PushNotificationConfig pushInfo) {
-        return CompletableFuture.supplyAsync(() -> dispatchNotification(task, pushInfo));
+    private CompletableFuture<Boolean> dispatch(StreamingEventKind kind, PushNotificationConfig pushInfo) {
+        return CompletableFuture.supplyAsync(() -> dispatchNotification(kind, pushInfo));
     }
 
-    private boolean dispatchNotification(Task task, PushNotificationConfig pushInfo) {
+    private boolean dispatchNotification(StreamingEventKind kind, PushNotificationConfig pushInfo) {
         String url = pushInfo.url();
         String token = pushInfo.token();
 
@@ -80,7 +100,7 @@ private boolean dispatchNotification(Task task, PushNotificationConfig pushInfo)
 
         String body;
         try {
-            body = Utils.OBJECT_MAPPER.writeValueAsString(task);
+            body = Utils.OBJECT_MAPPER.writeValueAsString(kind);
         } catch (JsonProcessingException e) {
             LOGGER.debug("Error writing value as string: {}", e.getMessage(), e);
             return false;

server-common/src/main/java/io/a2a/server/tasks/PushNotificationSender.java

@@ -1,15 +1,15 @@
 package io.a2a.server.tasks;
 
-import io.a2a.spec.Task;
+import io.a2a.spec.StreamingEventKind;
 
 /**
  * Interface for sending push notifications for tasks.
  */
 public interface PushNotificationSender {
 
     /**
-     * Sends a push notification containing the latest task state.
-     * @param task the task
+     * Sends a push notification with a payload related to the task.
+     * @param kind the payload to push
      */
-    void sendNotification(Task task);
+    void sendNotification(StreamingEventKind kind);
 }

server-common/src/test/java/io/a2a/server/tasks/PushNotificationSenderTest.java

@@ -16,6 +16,10 @@
 import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;
 
+import io.a2a.spec.Message;
+import io.a2a.spec.Part;
+import io.a2a.spec.StreamingEventKind;
+import io.a2a.spec.TextPart;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -67,6 +71,7 @@ class TestPostBuilder implements A2AHttpClient.PostBuilder {
             @Override
             public PostBuilder body(String body) {
                 this.body = body;
+                System.out.println("body = " + body);
                 return this;
             }
 
@@ -80,6 +85,7 @@ public A2AHttpResponse post() throws IOException, InterruptedException {
                     Task task = Utils.OBJECT_MAPPER.readValue(body, Task.TYPE_REFERENCE);
                     tasks.add(task);
                     urls.add(url);
+                    System.out.println(requestHeaders);
                     headers.add(new java.util.HashMap<>(requestHeaders));
 
                     return new A2AHttpResponse() {
@@ -95,7 +101,7 @@ public boolean success() {
 
                         @Override
                         public String body() {
-                            return "";
+                            return body;
                         }
                     };
                 } finally {
@@ -316,4 +322,45 @@ public void testSendNotificationHttpError() {
         // Verify no tasks were successfully processed due to the error
         assertEquals(0, testHttpClient.tasks.size());
     }
+
+    @Test
+    public void testSendNotificationWithMessage() throws InterruptedException {
+        String taskId = "task_send_notification_with_message";
+        Task taskData = createSampleTask(taskId, TaskState.COMPLETED);
+        PushNotificationConfig config = createSamplePushConfig("http://notify.me/here", "cfg1", "unique_token");
+
+        // Set up the configuration in the store
+        configStore.setInfo(taskId, config);
+
+        // Set up latch to wait for async completion
+        testHttpClient.latch = new CountDownLatch(1);
+
+        Message message = new Message.Builder()
+                .taskId(taskId)
+                .messageId("task_push_notification_message")
+                .parts(Collections.singletonList(new TextPart("Message for task " + taskId)))
+                .role(Message.Role.USER)
+                .build();
+        sender.sendNotification(message);
+
+        // Wait for the async operation to complete
+        assertTrue(testHttpClient.latch.await(5, TimeUnit.SECONDS), "HTTP call should complete within 5 seconds");
+
+        // Verify the task was sent via HTTP
+        assertEquals(1, testHttpClient.tasks.size());
+        Task sentTask = testHttpClient.tasks.get(0);
+        assertEquals(taskData.getId(), sentTask.getId());
+
+        // Verify that the X-A2A-Notification-Token header is sent with the correct token
+        assertEquals(1, testHttpClient.headers.size());
+        Map<String, String> sentHeaders = testHttpClient.headers.get(0);
+        assertEquals(2, sentHeaders.size());
+        assertTrue(sentHeaders.containsKey(A2AHeaders.X_A2A_NOTIFICATION_TOKEN));
+        assertEquals(config.token(), sentHeaders.get(A2AHeaders.X_A2A_NOTIFICATION_TOKEN));
+        // Content-Type header should always be present
+        assertTrue(sentHeaders.containsKey(CONTENT_TYPE));
+        assertEquals(APPLICATION_JSON, sentHeaders.get(CONTENT_TYPE));
+
+    }
+
 }