chore: 553: Addressed PR comments from Pull request 564. Changes related to PushNotificationConfig pagination feature

Author: Sathyvs

extras/push-notification-config-store-database-jpa/src/main/java/io/a2a/extras/pushnotificationconfigstore/database/jpa/JpaDatabasePushNotificationConfigStore.java

@@ -1,5 +1,8 @@
 package io.a2a.extras.pushnotificationconfigstore.database.jpa;
 
+import io.a2a.server.config.A2AConfigProvider;
+import jakarta.annotation.PostConstruct;
+import jakarta.inject.Inject;
 import jakarta.persistence.TypedQuery;
 import java.time.Instant;
 import java.util.List;
@@ -29,18 +32,42 @@ public class JpaDatabasePushNotificationConfigStore implements PushNotificationC
     private static final Logger LOGGER = LoggerFactory.getLogger(JpaDatabasePushNotificationConfigStore.class);
 
     private static final Instant NULL_TIMESTAMP_SENTINEL = Instant.EPOCH;
+    private static final String A2A_PUSH_NOTIFICATION_MAX_PAGE_SIZE_CONFIG = "a2a.push-notification-config.max-page-size";
+    private static final int A2A_PUSH_NOTIFICATION_DEFAULT_MAX_PAGE_SIZE = 100;
 
     @PersistenceContext(unitName = "a2a-java")
     EntityManager em;
 
+    @Inject
+    A2AConfigProvider configProvider;
+
+    /**
+     * Maximum page size when listing push notification configurations for a task.
+     * Requested page sizes exceeding this value will be capped to this limit.
+     * <p>
+     * Property: {@code a2a.push-notification-config.max-page-size}<br>
+     * Default: 100<br>
+     * Note: Property override requires a configurable {@link A2AConfigProvider} on the classpath.
+     */
+    int maxPageSize;
+
+    @PostConstruct
+    void initConfig() {
+      try {
+        maxPageSize = Integer.parseInt(configProvider.getValue(A2A_PUSH_NOTIFICATION_MAX_PAGE_SIZE_CONFIG));
+      } catch (Exception e) {
+        LOGGER.warn("Failed to read '{}' configuration, falling back to default page size of {}.",
+            A2A_PUSH_NOTIFICATION_MAX_PAGE_SIZE_CONFIG, A2A_PUSH_NOTIFICATION_DEFAULT_MAX_PAGE_SIZE, e);
+        maxPageSize = A2A_PUSH_NOTIFICATION_DEFAULT_MAX_PAGE_SIZE;
+      }
+    }
+
     @Transactional
     @Override
     public PushNotificationConfig setInfo(String taskId, PushNotificationConfig notificationConfig) {
         // Ensure config has an ID - default to taskId if not provided (mirroring InMemoryPushNotificationConfigStore behavior)
         PushNotificationConfig.Builder builder = PushNotificationConfig.builder(notificationConfig);
         if (notificationConfig.id() == null || notificationConfig.id().isEmpty()) {
-            // This means the taskId and configId are same. This will not allow having multiple configs for a single Task.
-            // The configId is a required field in the spec and should not be empty
             builder.id(taskId);
         }
         notificationConfig = builder.build();
@@ -80,44 +107,48 @@ public ListTaskPushNotificationConfigResult getInfo(ListTaskPushNotificationConf
         LOGGER.debug("Retrieving PushNotificationConfigs for Task '{}' with params: pageSize={}, pageToken={}",
             taskId, params.pageSize(), params.pageToken());
         try {
-            StringBuilder queryBuilder = new StringBuilder("SELECT c FROM JpaPushNotificationConfig c WHERE c.id.taskId = :taskId");
+            // Parse pageToken once upfront
+            Instant tokenTimestamp = null;
+            String tokenId = null;
 
             if (params.pageToken() != null && !params.pageToken().isEmpty()) {
-              String[] tokenParts = params.pageToken().split(":", 2);
-              if (tokenParts.length == 2) {
-                // Keyset pagination: get tasks where timestamp < tokenTimestamp OR (timestamp = tokenTimestamp AND id > tokenId)
-                // All tasks have timestamps (TaskStatus canonical constructor ensures this)
+                String[] tokenParts = params.pageToken().split(":", 2);
+                if (tokenParts.length != 2) {
+                    throw new io.a2a.spec.InvalidParamsError(null,
+                        "Invalid pageToken format: pageToken must be in 'timestamp_millis:configId' format", null);
+                }
+
+                try {
+                    long timestampMillis = Long.parseLong(tokenParts[0]);
+                    tokenTimestamp = Instant.ofEpochMilli(timestampMillis);
+                    tokenId = tokenParts[1];
+                } catch (NumberFormatException e) {
+                    throw new io.a2a.spec.InvalidParamsError(null,
+                        "Invalid pageToken format: timestamp must be numeric milliseconds", null);
+                }
+            }
+
+            // Build query using the parsed values
+            StringBuilder queryBuilder = new StringBuilder("SELECT c FROM JpaPushNotificationConfig c WHERE c.id.taskId = :taskId");
+
+            if (tokenTimestamp != null) {
+                // Keyset pagination: get notifications where timestamp < tokenTimestamp OR (timestamp = tokenTimestamp AND id > tokenId)
                 queryBuilder.append(" AND (COALESCE(c.createdAt, :nullSentinel) < :tokenTimestamp OR (COALESCE(c.createdAt, :nullSentinel) = :tokenTimestamp AND c.id.configId > :tokenId))");
-              } else {
-                // Based on the comments in the test case, if the pageToken is invalid start from the beginning.
-              }
             }
 
             queryBuilder.append(" ORDER BY  COALESCE(c.createdAt, :nullSentinel) DESC, c.id.configId ASC");
 
+            // Create query and set parameters
             TypedQuery<JpaPushNotificationConfig> query = em.createQuery(queryBuilder.toString(), JpaPushNotificationConfig.class);
             query.setParameter("taskId", taskId);
             query.setParameter("nullSentinel", NULL_TIMESTAMP_SENTINEL);
 
-            if (params.pageToken() != null && !params.pageToken().isEmpty()) {
-              String[] tokenParts = params.pageToken().split(":", 2);
-              if (tokenParts.length == 2) {
-                try {
-                  long timestampMillis = Long.parseLong(tokenParts[0]);
-                  String tokenId = tokenParts[1];
-
-                  Instant tokenTimestamp = Instant.ofEpochMilli(timestampMillis);
-                  query.setParameter("tokenTimestamp", tokenTimestamp);
-                  query.setParameter("tokenId", tokenId);
-                } catch (NumberFormatException e) {
-                  // Malformed timestamp in pageToken
-                  throw new io.a2a.spec.InvalidParamsError(null,
-                      "Invalid pageToken format: timestamp must be numeric milliseconds", null);
-                }
-              }
+            if (tokenTimestamp != null) {
+                query.setParameter("tokenTimestamp", tokenTimestamp);
+                query.setParameter("tokenId", tokenId);
             }
 
-            int pageSize = params.getEffectivePageSize();
+            int pageSize = params.getEffectivePageSize(maxPageSize);
             query.setMaxResults(pageSize + 1);
             List<JpaPushNotificationConfig> jpaConfigsPage = query.getResultList();
 

extras/push-notification-config-store-database-jpa/src/main/resources/META-INF/a2a-defaults.properties

@@ -0,0 +1,7 @@
+# A2A JPA Database Push Notification Config Store Default Configuration
+
+# Maximum page size when listing push notification configurations for a task
+# Requested page sizes exceeding this value will be capped to this limit
+# Used as default when pageSize parameter is not specified or is invalid
+a2a.push-notification-config.max-page-size=100
+

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

@@ -7,6 +7,7 @@
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import io.a2a.spec.InvalidParamsError;
 import java.util.List;
 import java.util.Queue;
 import java.util.concurrent.CountDownLatch;
@@ -293,7 +294,7 @@ public void testPaginationWithZeroPageSize() {
         ListTaskPushNotificationConfigResult result = pushNotificationConfigStore.getInfo(params);
 
         assertNotNull(result);
-        assertEquals(5, result.configs().size(), "Should return all 5 configs when pageSize=0");
+        assertEquals(5, result.configs().size(), "Should return all default capped 5 configs when pageSize=0");
         assertNull(result.nextPageToken(), "Should not have nextPageToken when returning all");
     }
 
@@ -355,12 +356,10 @@ public void testPaginationWithInvalidToken() {
         // Request with invalid pageToken - JPA implementation behavior is to start from beginning
         ListTaskPushNotificationConfigParams params = new ListTaskPushNotificationConfigParams(
                 taskId, 2, "invalid_token_that_does_not_exist", "");
-        ListTaskPushNotificationConfigResult result = pushNotificationConfigStore.getInfo(params);
 
-        assertNotNull(result);
-        // When token is not found, implementation starts from beginning
-        assertEquals(2, result.configs().size(), "Should return first page when token is not found");
-        assertNotNull(result.nextPageToken(), "Should have nextPageToken since more items exist");
+        assertThrows(InvalidParamsError.class, () ->
+          pushNotificationConfigStore.getInfo(params),
+            "Invalid pageToken format: pageToken must be in 'timestamp_millis:configId' format");
     }
 
     @Test
@@ -428,12 +427,10 @@ public void testPageTokenWithMissingColon() {
 
       ListTaskPushNotificationConfigParams params =
           new ListTaskPushNotificationConfigParams(taskId, 2, "123456789cfg1", "");
-      ListTaskPushNotificationConfigResult result = pushNotificationConfigStore.getInfo(params);
 
-      assertNotNull(result);
-      assertEquals(2, result.configs().size(),
-          "Should return first page when pageToken format is invalid (missing colon)");
-      assertNotNull(result.nextPageToken(), "Should have nextPageToken since more items exist");
+      assertThrows(InvalidParamsError.class, () ->
+              pushNotificationConfigStore.getInfo(params),
+          "Invalid pageToken format: pageToken must be in 'timestamp_millis:configId' format");
     }
 
     @Test
@@ -552,6 +549,47 @@ public void testPaginationOrderingConsistency() {
       assertEquals("cfg0", allConfigIds.get(14),
           "Last config should be oldest created");
     }
+
+    @Test
+    @Transactional
+    public void testPageSizeExceedingConfiguredMaxLimit() {
+      String taskId = "task_max_page_size_" + System.currentTimeMillis();
+      // Create 5 configs (more than test max page size of 5)
+      createSamples(taskId, 7);
+
+      // Request with pageSize=7 (exceeds configured max of 5 in test application.properties)
+      // Should be capped to maxPageSize (5) from config
+      ListTaskPushNotificationConfigParams params =
+          new ListTaskPushNotificationConfigParams(taskId, 7, "", "");
+      ListTaskPushNotificationConfigResult result = pushNotificationConfigStore.getInfo(params);
+
+      assertNotNull(result);
+      // Should return 5 configs (capped to maxPageSize from test config), not 7
+      assertEquals(5, result.configs().size(),
+          "Page size should be capped to configured maxPageSize (5 in tests) when requested size exceeds limit");
+      assertNotNull(result.nextPageToken(),
+          "Should have nextPageToken since more configs remain");
+
+      // Verify we can iterate through all pages and get all 7 configs
+      List<String> allConfigIds = new java.util.ArrayList<>();
+      result.configs().forEach(c -> allConfigIds.add(c.pushNotificationConfig().id()));
+
+      String nextToken = result.nextPageToken();
+      while (nextToken != null) {
+        ListTaskPushNotificationConfigParams nextParams =
+            new ListTaskPushNotificationConfigParams(taskId, 7, nextToken, "");
+        ListTaskPushNotificationConfigResult nextResult = pushNotificationConfigStore.getInfo(nextParams);
+
+        nextResult.configs().forEach(c -> allConfigIds.add(c.pushNotificationConfig().id()));
+        nextToken = nextResult.nextPageToken();
+      }
+
+      assertEquals(7, allConfigIds.size(),
+          "Should retrieve all 7 configs across multiple pages");
+      assertEquals(7, new java.util.HashSet<>(allConfigIds).size(),
+          "All config IDs should be unique - no duplicates");
+    }
+
   private void createSamples(String taskId, int size) {
         // Create configs with slight delays to ensure unique timestamps for deterministic ordering
         for (int i = 0; i < size; i++) {

extras/push-notification-config-store-database-jpa/src/test/resources/META-INF/a2a-test-defaults.properties

@@ -0,0 +1,28 @@
+# A2A SDK Default Configuration Values
+# These values are used when no other configuration source provides them
+
+# DefaultRequestHandler - Blocking call timeouts
+# Timeout for agent execution to complete (seconds)
+# Increase for slow agents: LLM-based, data processing, external APIs
+a2a.blocking.agent.timeout.seconds=30
+
+# Timeout for event consumption/persistence to complete (seconds)
+# Ensures TaskStore is fully updated before returning to client
+a2a.blocking.consumption.timeout.seconds=5
+
+# AsyncExecutorProducer - Thread pool configuration
+# Core pool size for async agent execution
+a2a.executor.core-pool-size=5
+
+# Maximum pool size for async agent execution
+a2a.executor.max-pool-size=50
+
+# Keep-alive time for idle threads (seconds)
+a2a.executor.keep-alive-seconds=60
+
+# A2A JPA Database Push Notification Config Store Default Configuration
+
+# A2A Configuration - Override max page size for testing
+# Set to a lower value (2) to make tests faster and verify capping behavior
+a2a.push-notification-config.max-page-size=5
+

extras/push-notification-config-store-database-jpa/src/test/resources/application.properties

@@ -12,3 +12,4 @@ quarkus.hibernate-orm.log.format-sql=true
 
 # Transaction timeout (set to 30 minutes for debugging - 1800 seconds)
 # quarkus.transaction-manager.default-transaction-timeout=1800s
+a2a.defaults.resource=META-INF/a2a-test-defaults.properties

server-common/pom.xml

@@ -62,7 +62,6 @@
         <dependency>
             <groupId>io.quarkus</groupId>
             <artifactId>quarkus-arc</artifactId>
-            <scope>test</scope>
             <exclusions>
                 <exclusion>
                     <groupId>org.jboss.logging</groupId>

server-common/src/main/java/io/a2a/server/config/DefaultValuesConfigProvider.java

@@ -12,6 +12,7 @@
 import jakarta.annotation.PostConstruct;
 import jakarta.enterprise.context.ApplicationScoped;
 
+import org.eclipse.microprofile.config.inject.ConfigProperty;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -31,6 +32,9 @@ public class DefaultValuesConfigProvider implements A2AConfigProvider {
     private static final Logger LOGGER = LoggerFactory.getLogger(DefaultValuesConfigProvider.class);
     private static final String DEFAULTS_RESOURCE = "META-INF/a2a-defaults.properties";
 
+    @ConfigProperty(name = "a2a.defaults.resource", defaultValue = DEFAULTS_RESOURCE)
+    String defaultsResource = DEFAULTS_RESOURCE;
+
     private final Map<String, String> defaults = new HashMap<>();
 
     @PostConstruct
@@ -42,7 +46,7 @@ private void loadDefaultsFromClasspath() {
         try {
             Enumeration<URL> resources = Thread.currentThread()
                     .getContextClassLoader()
-                    .getResources(DEFAULTS_RESOURCE);
+                    .getResources(defaultsResource);
 
             Map<String, String> sourceTracker = new HashMap<>(); // Track which file each key came from
 

spec/src/main/java/io/a2a/spec/ListTaskPushNotificationConfigParams.java

@@ -39,13 +39,15 @@ public ListTaskPushNotificationConfigParams(String id) {
     }
 
     /**
-     * Validates and returns the effective page size (between 1 and 100, defaults to 100).
+     * Validates and returns the effective page size.
+     * If the requested pageSize is invalid (≤ 0 or > maxPageSize), returns maxPageSize.
      *
-     * @return the effective page size
+     * @param maxPageSize the maximum allowed page size
+     * @return the effective page size (between 1 and maxPageSize)
      */
-    public int getEffectivePageSize() {
-      if (pageSize <= 0 || pageSize > 100) {
-        return 100;
+    public int getEffectivePageSize(int maxPageSize) {
+      if (pageSize <= 0 || pageSize > maxPageSize) {
+        return maxPageSize;
       }
       return pageSize;
     }