[ECO-5458][LiveObjects] Implement object subscriptions #1130

sacOO7 · 2025-07-21T12:11:37Z

Summary by CodeRabbit

New Features
- Introduced real-time subscription and notification capabilities for LiveMap and LiveCounter objects, allowing users to receive updates when values or entries change.
- Added explicit update event types for LiveMap (UPDATED, REMOVED) and LiveCounter (increment/decrement amounts).
- Provided methods to subscribe, unsubscribe, and manage listeners for live object updates.
Bug Fixes
- Improved handling of no-op updates and tombstoned objects for more accurate event propagation.
Tests
- Added integration tests verifying subscription, update delivery, and unsubscription for LiveMap and LiveCounter objects.
- Updated unit tests to validate new update event structures and types.
Documentation
- Enhanced in-code documentation and comments, including specification references and detailed KDoc for helper functions.
Refactor
- Refined update handling from generic maps to strongly-typed update objects for better clarity and consistency.
- Modularized and documented fixture and helper code for improved maintainability.
Style
- Improved code formatting and import organization for readability.

coderabbitai · 2025-07-21T12:11:43Z

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📥 Commits

Reviewing files that changed from the base of the PR and between ae81bbc and 86c08f6.

📒 Files selected for processing (2)

live-objects/src/main/kotlin/io/ably/lib/objects/type/livecounter/LiveCounterChangeCoordinator.kt (1 hunks)
live-objects/src/main/kotlin/io/ably/lib/objects/type/livemap/LiveMapChangeCoordinator.kt (1 hunks)

Walkthrough

This change introduces a comprehensive data subscription mechanism for live objects, particularly LiveMap and LiveCounter, across Java and Kotlin codebases. It adds new update abstractions, subscription interfaces, event coordinators, and modifies object state handling to use strongly-typed update classes. Integration and unit tests are updated and extended to verify the new subscription and notification flows.

Changes

Cohort / File(s)	Change Summary
Java API: Subscription & Update Abstractions `lib/src/main/java/io/ably/lib/objects/type/LiveObjectUpdate.java`, `lib/src/main/java/io/ably/lib/objects/type/counter/LiveCounterChange.java`, `lib/src/main/java/io/ably/lib/objects/type/counter/LiveCounterUpdate.java`, `lib/src/main/java/io/ably/lib/objects/type/map/LiveMapChange.java`, `lib/src/main/java/io/ably/lib/objects/type/map/LiveMapUpdate.java`, `lib/src/main/java/io/ably/lib/objects/ObjectsSubscription.java`	Introduces update abstraction (`LiveObjectUpdate`), strongly-typed update classes (`LiveCounterUpdate`, `LiveMapUpdate`), and subscription interfaces (`LiveCounterChange`, `LiveMapChange`). Adds specification comments to `ObjectsSubscription`.
Java API: Type & Interface Relocation `lib/src/main/java/io/ably/lib/objects/type/counter/LiveCounter.java`, `lib/src/main/java/io/ably/lib/objects/type/map/LiveMap.java`, `lib/src/main/java/io/ably/lib/objects/LiveObjects.java`	Moves `LiveCounter` and `LiveMap` interfaces to type-specific packages and updates them to extend their respective change interfaces. Adds relevant imports.
Kotlin Core: Base Object and Manager Refactor `live-objects/src/main/kotlin/io/ably/lib/objects/type/BaseLiveObject.kt`, `live-objects/src/main/kotlin/io/ably/lib/objects/ObjectsManager.kt`, `live-objects/src/main/kotlin/io/ably/lib/objects/DefaultLiveObjects.kt`, `live-objects/src/main/kotlin/io/ably/lib/objects/Helpers.kt`, `live-objects/src/main/kotlin/io/ably/lib/objects/ObjectsPool.kt`	Refactors base object methods to use `LiveObjectUpdate` instead of generic maps, enforces typed notification, and adds spec comments. Refines internal update handling and imports.
Kotlin: LiveCounter Implementation `live-objects/src/main/kotlin/io/ably/lib/objects/type/livecounter/DefaultLiveCounter.kt`, `live-objects/src/main/kotlin/io/ably/lib/objects/type/livecounter/LiveCounterManager.kt`, `live-objects/src/main/kotlin/io/ably/lib/objects/type/livecounter/LiveCounterChangeCoordinator.kt`	Adds subscription management and notification for `LiveCounter`. Refactors state and operation methods to use `LiveCounterUpdate`. Implements event coordination and emission for counter updates.
Kotlin: LiveMap Implementation `live-objects/src/main/kotlin/io/ably/lib/objects/type/livemap/DefaultLiveMap.kt`, `live-objects/src/main/kotlin/io/ably/lib/objects/type/livemap/LiveMapManager.kt`, `live-objects/src/main/kotlin/io/ably/lib/objects/type/livemap/LiveMapChangeCoordinator.kt`	Adds subscription management and notification for `LiveMap`. Refactors state and operation methods to use `LiveMapUpdate`. Implements event coordination and emission for map updates.
Integration Tests: Subscription Coverage `live-objects/src/test/kotlin/io/ably/lib/objects/integration/DefaultLiveCounterTest.kt`, `live-objects/src/test/kotlin/io/ably/lib/objects/integration/DefaultLiveMapTest.kt`, `live-objects/src/test/kotlin/io/ably/lib/objects/integration/DefaultLiveObjectsTest.kt`, `live-objects/src/test/kotlin/io/ably/lib/objects/integration/setup/IntegrationTest.kt`	Adds new integration tests for live counter and map subscriptions, updates imports, and increases test timeout.
Test Helpers & Fixtures `live-objects/src/test/kotlin/io/ably/lib/objects/integration/helpers/RestObjects.kt`, `live-objects/src/test/kotlin/io/ably/lib/objects/integration/helpers/Utils.kt`, `live-objects/src/test/kotlin/io/ably/lib/objects/integration/helpers/fixtures/CounterFixtures.kt`, `live-objects/src/test/kotlin/io/ably/lib/objects/integration/helpers/fixtures/MapFixtures.kt`	Refactors map/counter fixture creation into helper functions with documentation. Updates imports and data creation logic.
Unit Tests: Update Type Adaptation `live-objects/src/test/kotlin/io/ably/lib/objects/unit/type/livecounter/LiveCounterManagerTest.kt`, `live-objects/src/test/kotlin/io/ably/lib/objects/unit/type/livemap/LiveMapManagerTest.kt`	Updates assertions and test logic to expect new strongly-typed update objects and enums.

Sequence Diagram(s)

sequenceDiagram
    participant Client
    participant LiveMap/LiveCounter
    participant Manager/Coordinator
    participant Listener

    Client->>LiveMap/LiveCounter: subscribe(listener)
    LiveMap/LiveCounter->>Manager/Coordinator: register listener
    Manager/Coordinator-->>Client: ObjectsSubscription

    Note over LiveMap/LiveCounter,Manager/Coordinator: State change occurs (e.g., set, inc)
    LiveMap/LiveCounter->>Manager/Coordinator: notifyUpdated(LiveObjectUpdate)
    Manager/Coordinator->>Listener: onUpdated(LiveMapUpdate/LiveCounterUpdate)

    Client->>LiveMap/LiveCounter: unsubscribe(listener)
    LiveMap/LiveCounter->>Manager/Coordinator: remove listener

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Assessment against linked issues

Objective	Addressed	Explanation
Implement BaseLiveObject#data-subscriptions for LiveMap and LiveCounter, including subscription APIs, update notification, and listener management (#1123, ECO-5458)	✅
Use strongly-typed update abstractions and event-driven notification for live object changes (#1123, ECO-5458)	✅
Add and update integration/unit tests to verify subscription and notification flows (#1123, ECO-5458)	✅

Assessment against linked issues: Out-of-scope changes

Code Change	Explanation
Refactoring fixture creation to helper functions with documentation (`live-objects/src/test/kotlin/io/ably/lib/objects/integration/helpers/fixtures/CounterFixtures.kt`, `MapFixtures.kt`)	While helpful for test clarity, modularizing fixture creation is not strictly required for implementing data subscriptions.
Increasing test timeout (`live-objects/src/test/kotlin/io/ably/lib/objects/integration/setup/IntegrationTest.kt`)	Raising the integration test timeout is not directly related to the core subscription feature objectives.

Possibly related PRs

Setup : LiveObject plugin #1085: Introduces foundational LiveObjects plugin interfaces and integration, which are extended and built upon in this PR for subscription and update mechanisms.

Suggested reviewers

ttypic

Poem

In the warren where updates hop and leap,
LiveMaps and Counters now secrets keep.
Subscriptions bloom, listeners awake,
Notified with every change we make.
Typed updates bound with carrot string—
Oh, what joy these new features bring!
🥕✨

✨ Finishing Touches

📝 Generate Docstrings

🧪 Generate unit tests

Create PR with unit tests
Post copyable unit tests in a comment
Commit unit tests in branch feature/object-subscriptions

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…rit LiveObjectUpdate 1. Updated mapManager to return LiveMapUpdate instead of Map 2. Updated counterManager to return LiveCounterUpdate instead of map 3. Updated BaseLiveObject accordingly

- Added toString methods to pretty print update

# Conflicts: # live-objects/src/main/kotlin/io/ably/lib/objects/type/BaseLiveObject.kt # live-objects/src/main/kotlin/io/ably/lib/objects/type/livecounter/DefaultLiveCounter.kt # live-objects/src/main/kotlin/io/ably/lib/objects/type/livecounter/LiveCounterManager.kt # live-objects/src/main/kotlin/io/ably/lib/objects/type/livemap/DefaultLiveMap.kt # live-objects/src/test/kotlin/io/ably/lib/objects/unit/type/livemap/LiveMapManagerTest.kt

coderabbitai

Actionable comments posted: 3

♻️ Duplicate comments (1)

live-objects/src/main/kotlin/io/ably/lib/objects/type/livecounter/LiveCounterChangeCoordinator.kt (1)
43-49: Avoid force unwrapping in listener callback.

Same issue as in LiveMapChangeCoordinator - the force unwrap operation event!! could cause a NullPointerException.
   override fun apply(listener: LiveCounterChange.Listener?, event: LiveCounterUpdate?, vararg args: Any?) {
     try {
-      listener?.onUpdated(event!!)
+      event?.let { listener?.onUpdated(it) }
+        ?: Log.w(tag, "Null event passed to listener callback")
     } catch (t: Throwable) {
       Log.e(tag, "Error occurred while executing listener callback for event: $event", t)
     }
   }

🧹 Nitpick comments (4)

lib/src/main/java/io/ably/lib/objects/type/counter/LiveCounterUpdate.java (1)
59-79: Consider design consistency with LiveMapUpdate's enum approach.

The nested Update class stores a single Double amount, while LiveMapUpdate uses an enum for change types. For a simple value like Double, this might be over-engineered compared to storing the Double directly in the parent class.

Consider simplifying by storing the Double directly:
public LiveCounterUpdate(@NotNull Double amount) {
-    super(new Update(amount));
+    super(amount);
}

@NotNull
public Double getUpdate() {
-    return (Update) update;
+    return (Double) update;
}
This would eliminate the nested class and align better with the simpler data structure needed for counter updates.
live-objects/src/test/kotlin/io/ably/lib/objects/integration/DefaultLiveMapTest.kt (1)
303-306: Improve unsubscription verification logic.

The current approach of waiting for the map size to change doesn't guarantee that enough time has passed to verify that no subscription callbacks were triggered. Consider adding an explicit delay to ensure the callback would have been invoked if the subscription was still active.
     // Wait for a moment to ensure no updates are received
     assertWaiter { userProfile.size() == 4L }
+    // Add explicit delay to ensure callbacks would have been processed
+    delay(500)
 
     assertTrue(userProfileUpdates.isEmpty(), "No updates should be received after unsubscribing")
live-objects/src/main/kotlin/io/ably/lib/objects/type/livecounter/LiveCounterManager.kt (1)
36-36: Consider handling edge cases in counter subtraction.

When calculating the update amount, if the counter was reset or had unexpected changes, the subtraction might not accurately reflect the actual change. Consider adding validation or logging for unusual cases.
-    return LiveCounterUpdate(liveCounter.data.get() - previousData)
+    val changeAmount = liveCounter.data.get() - previousData
+    if (kotlin.math.abs(changeAmount) > 1e9) {
+      Log.w(tag, "Unusually large counter change detected: $changeAmount for objectId=$objectId")
+    }
+    return LiveCounterUpdate(changeAmount)
live-objects/src/main/kotlin/io/ably/lib/objects/type/BaseLiveObject.kt (1)
56-62: Consider using when expression for better readability.

The if-else chain could be replaced with a when expression for better readability and compile-time exhaustiveness checking.
     if (isTombstoned) {
       // this object is tombstoned. this is a terminal state which can't be overridden. skip the rest of object state message processing
-      if (objectType == ObjectType.Map) {
-        return noOpMapUpdate
-      }
-      return noOpCounterUpdate
+      return when (objectType) {
+        ObjectType.Map -> noOpMapUpdate
+        ObjectType.Counter -> noOpCounterUpdate
+      }
     }

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📥 Commits

Reviewing files that changed from the base of the PR and between 6d7f0fe and 1847ba8.

📒 Files selected for processing (28)

lib/src/main/java/io/ably/lib/objects/LiveObjects.java (1 hunks)
lib/src/main/java/io/ably/lib/objects/type/LiveObjectUpdate.java (1 hunks)
lib/src/main/java/io/ably/lib/objects/type/counter/LiveCounter.java (2 hunks)
lib/src/main/java/io/ably/lib/objects/type/counter/LiveCounterChange.java (1 hunks)
lib/src/main/java/io/ably/lib/objects/type/counter/LiveCounterUpdate.java (1 hunks)
lib/src/main/java/io/ably/lib/objects/type/map/LiveMap.java (2 hunks)
lib/src/main/java/io/ably/lib/objects/type/map/LiveMapChange.java (1 hunks)
lib/src/main/java/io/ably/lib/objects/type/map/LiveMapUpdate.java (1 hunks)
live-objects/src/main/kotlin/io/ably/lib/objects/DefaultLiveObjects.kt (3 hunks)
live-objects/src/main/kotlin/io/ably/lib/objects/ObjectsManager.kt (3 hunks)
live-objects/src/main/kotlin/io/ably/lib/objects/type/BaseLiveObject.kt (7 hunks)
live-objects/src/main/kotlin/io/ably/lib/objects/type/livecounter/DefaultLiveCounter.kt (2 hunks)
live-objects/src/main/kotlin/io/ably/lib/objects/type/livecounter/LiveCounterChangeCoordinator.kt (1 hunks)
live-objects/src/main/kotlin/io/ably/lib/objects/type/livecounter/LiveCounterManager.kt (6 hunks)
live-objects/src/main/kotlin/io/ably/lib/objects/type/livemap/DefaultLiveMap.kt (2 hunks)
live-objects/src/main/kotlin/io/ably/lib/objects/type/livemap/LiveMapChangeCoordinator.kt (1 hunks)
live-objects/src/main/kotlin/io/ably/lib/objects/type/livemap/LiveMapManager.kt (14 hunks)
live-objects/src/test/kotlin/io/ably/lib/objects/integration/DefaultLiveCounterTest.kt (2 hunks)
live-objects/src/test/kotlin/io/ably/lib/objects/integration/DefaultLiveMapTest.kt (2 hunks)
live-objects/src/test/kotlin/io/ably/lib/objects/integration/DefaultLiveObjectsTest.kt (1 hunks)
live-objects/src/test/kotlin/io/ably/lib/objects/integration/helpers/RestObjects.kt (2 hunks)
live-objects/src/test/kotlin/io/ably/lib/objects/integration/helpers/Utils.kt (1 hunks)
live-objects/src/test/kotlin/io/ably/lib/objects/integration/helpers/fixtures/CounterFixtures.kt (2 hunks)
live-objects/src/test/kotlin/io/ably/lib/objects/integration/helpers/fixtures/MapFixtures.kt (2 hunks)
live-objects/src/test/kotlin/io/ably/lib/objects/integration/setup/IntegrationTest.kt (1 hunks)
live-objects/src/test/kotlin/io/ably/lib/objects/unit/ObjectMessageSizeTest.kt (0 hunks)
live-objects/src/test/kotlin/io/ably/lib/objects/unit/type/livecounter/LiveCounterManagerTest.kt (2 hunks)
live-objects/src/test/kotlin/io/ably/lib/objects/unit/type/livemap/LiveMapManagerTest.kt (12 hunks)

🧠 Learnings (25)

📓 Common learnings

Learnt from: sacOO7
PR: ably/ably-java#1087
File: lib/src/main/java/io/ably/lib/objects/LiveObjectsAdapter.java:32-34
Timestamp: 2025-05-27T12:11:25.084Z
Learning: In LiveObjects implementation (lib/src/main/java/io/ably/lib/objects/LiveObjectsAdapter.java), the send method intentionally hardcodes queueEvents to true rather than respecting ably.options.queueMessages. This is because LiveObjects requires reliable message delivery to ensure proper state synchronization and acknowledgment, unlike other realtime components that may allow configurable queuing behavior.

Learnt from: sacOO7
PR: ably/ably-java#1092
File: live-objects/src/test/kotlin/io/ably/lib/objects/TestUtils.kt:48-61
Timestamp: 2025-06-03T09:15:18.827Z
Learning: User sacOO7 prefers simple test utilities without extensive error handling, believing tests should fail fast if incorrect field/method names are used rather than having defensive programming.

lib/src/main/java/io/ably/lib/objects/LiveObjects.java (7)

Learnt from: sacOO7
PR: #1106
File: live-objects/src/main/kotlin/io/ably/lib/objects/serialization/Serialization.kt:25-29
Timestamp: 2025-06-23T14:18:25.315Z
Learning: In the ably-java codebase, the DefaultLiveObjectSerializer class methods like writeMsgpackArray will have their type signatures updated to be non-nullable since the calling sites ensure objects are never null when passed to these methods.

Learnt from: sacOO7
PR: #1092
File: live-objects/src/test/kotlin/io/ably/lib/objects/TestUtils.kt:21-32
Timestamp: 2025-06-03T09:15:15.338Z
Learning: In test utility code for the Ably Java Live Objects module, the team prefers to keep reflection-based field access utilities simple without additional error handling, allowing tests to fail fast if incorrect field names are used.

Learnt from: sacOO7
PR: #1085
File: lib/src/main/java/io/ably/lib/objects/LiveObjects.java:0-0
Timestamp: 2025-05-20T13:12:19.013Z
Learning: The LiveObjects interface does not currently include public API methods for resource management (dispose) or change listeners, as these features are not yet implemented.

Learnt from: sacOO7
PR: #1087
File: live-objects/src/main/kotlin/io/ably/lib/objects/ObjectMessage.kt:198-198
Timestamp: 2025-05-27T12:12:10.782Z
Learning: In Kotlin/Java codebases, when referencing types (classes, enums, interfaces) that are defined in the same package, no import statement is required as they are automatically accessible due to package-private visibility.

Learnt from: sacOO7
PR: #1087
File: lib/src/main/java/io/ably/lib/objects/LiveObjectsAdapter.java:32-34
Timestamp: 2025-05-27T12:11:25.084Z
Learning: In LiveObjects implementation (lib/src/main/java/io/ably/lib/objects/LiveObjectsAdapter.java), the send method intentionally hardcodes queueEvents to true rather than respecting ably.options.queueMessages. This is because LiveObjects requires reliable message delivery to ensure proper state synchronization and acknowledgment, unlike other realtime components that may allow configurable queuing behavior.

Learnt from: sacOO7
PR: #1106
File: live-objects/src/main/kotlin/io/ably/lib/objects/serialization/Serialization.kt:38-46
Timestamp: 2025-06-23T14:14:17.847Z
Learning: In the ably-java codebase, the DefaultLiveObjectSerializer class uses intentional unsafe casting (objects as Array<ObjectMessage>) without type validation in both writeMsgpackArray and asJsonArray methods. This is a deliberate design decision to keep the dynamically-loaded class simple and let ClassCastException occur naturally for type mismatches.

Learnt from: sacOO7
PR: #1095
File: live-objects/src/test/kotlin/io/ably/lib/objects/integration/setup/IntegrationTest.kt:87-89
Timestamp: 2025-06-06T09:28:12.298Z
Learning: The Sandbox.kt file in ably-java live-objects module already has comprehensive HTTP retry mechanism using HttpRequestRetry with 5 retries, exponential backoff, and automatic retry on non-success responses and timeout exceptions.

live-objects/src/test/kotlin/io/ably/lib/objects/integration/helpers/Utils.kt (7)

Learnt from: sacOO7
PR: #1095
File: live-objects/src/test/kotlin/io/ably/lib/objects/unit/LiveObjectTest.kt:1-6
Timestamp: 2025-06-05T10:24:28.789Z
Learning: In Kotlin, functions, classes, and other declarations within the same package are automatically accessible without explicit import statements. Do not suggest adding imports for functions/classes that are already in the same package.

Learnt from: sacOO7
PR: #1087
File: live-objects/src/main/kotlin/io/ably/lib/objects/ObjectMessage.kt:198-198
Timestamp: 2025-05-27T12:12:10.782Z
Learning: In Kotlin/Java codebases, when referencing types (classes, enums, interfaces) that are defined in the same package, no import statement is required as they are automatically accessible due to package-private visibility.

Learnt from: sacOO7
PR: #1092
File: live-objects/src/test/kotlin/io/ably/lib/objects/TestUtils.kt:21-32
Timestamp: 2025-06-03T09:15:15.338Z
Learning: In test utility code for the Ably Java Live Objects module, the team prefers to keep reflection-based field access utilities simple without additional error handling, allowing tests to fail fast if incorrect field names are used.

Learnt from: sacOO7
PR: #1106
File: live-objects/src/main/kotlin/io/ably/lib/objects/serialization/Serialization.kt:25-29
Timestamp: 2025-06-23T14:18:25.315Z
Learning: In the ably-java codebase, the DefaultLiveObjectSerializer class methods like writeMsgpackArray will have their type signatures updated to be non-nullable since the calling sites ensure objects are never null when passed to these methods.

Learnt from: sacOO7
PR: #1085
File: lib/src/main/java/io/ably/lib/objects/LiveObjects.java:0-0
Timestamp: 2025-05-20T13:12:19.013Z
Learning: The LiveObjects interface does not currently include public API methods for resource management (dispose) or change listeners, as these features are not yet implemented.

Learnt from: sacOO7
PR: #1087
File: lib/src/main/java/io/ably/lib/objects/LiveObjectsAdapter.java:32-34
Timestamp: 2025-05-27T12:11:25.084Z
Learning: In LiveObjects implementation (lib/src/main/java/io/ably/lib/objects/LiveObjectsAdapter.java), the send method intentionally hardcodes queueEvents to true rather than respecting ably.options.queueMessages. This is because LiveObjects requires reliable message delivery to ensure proper state synchronization and acknowledgment, unlike other realtime components that may allow configurable queuing behavior.

Learnt from: sacOO7
PR: #1106
File: live-objects/src/main/kotlin/io/ably/lib/objects/serialization/Serialization.kt:38-46
Timestamp: 2025-06-23T14:14:17.847Z
Learning: In the ably-java codebase, the DefaultLiveObjectSerializer class uses intentional unsafe casting (objects as Array<ObjectMessage>) without type validation in both writeMsgpackArray and asJsonArray methods. This is a deliberate design decision to keep the dynamically-loaded class simple and let ClassCastException occur naturally for type mismatches.

live-objects/src/test/kotlin/io/ably/lib/objects/unit/type/livecounter/LiveCounterManagerTest.kt (1)

Learnt from: sacOO7
PR: #1106
File: live-objects/src/main/kotlin/io/ably/lib/objects/serialization/Serialization.kt:25-29
Timestamp: 2025-06-23T14:18:25.315Z
Learning: In the ably-java codebase, the DefaultLiveObjectSerializer class methods like writeMsgpackArray will have their type signatures updated to be non-nullable since the calling sites ensure objects are never null when passed to these methods.

lib/src/main/java/io/ably/lib/objects/type/map/LiveMap.java (3)

Learnt from: sacOO7
PR: #1106
File: live-objects/src/main/kotlin/io/ably/lib/objects/serialization/Serialization.kt:25-29
Timestamp: 2025-06-23T14:18:25.315Z
Learning: In the ably-java codebase, the DefaultLiveObjectSerializer class methods like writeMsgpackArray will have their type signatures updated to be non-nullable since the calling sites ensure objects are never null when passed to these methods.

Learnt from: sacOO7
PR: #1092
File: live-objects/src/test/kotlin/io/ably/lib/objects/TestUtils.kt:21-32
Timestamp: 2025-06-03T09:15:15.338Z
Learning: In test utility code for the Ably Java Live Objects module, the team prefers to keep reflection-based field access utilities simple without additional error handling, allowing tests to fail fast if incorrect field names are used.

Learnt from: sacOO7
PR: #1106
File: live-objects/src/main/kotlin/io/ably/lib/objects/serialization/Serialization.kt:38-46
Timestamp: 2025-06-23T14:14:17.847Z
Learning: In the ably-java codebase, the DefaultLiveObjectSerializer class uses intentional unsafe casting (objects as Array<ObjectMessage>) without type validation in both writeMsgpackArray and asJsonArray methods. This is a deliberate design decision to keep the dynamically-loaded class simple and let ClassCastException occur naturally for type mismatches.

lib/src/main/java/io/ably/lib/objects/type/counter/LiveCounter.java (1)

Learnt from: sacOO7
PR: #1106
File: live-objects/src/main/kotlin/io/ably/lib/objects/serialization/Serialization.kt:25-29
Timestamp: 2025-06-23T14:18:25.315Z
Learning: In the ably-java codebase, the DefaultLiveObjectSerializer class methods like writeMsgpackArray will have their type signatures updated to be non-nullable since the calling sites ensure objects are never null when passed to these methods.

live-objects/src/test/kotlin/io/ably/lib/objects/integration/setup/IntegrationTest.kt (1)

Learnt from: sacOO7
PR: #1095
File: live-objects/src/test/kotlin/io/ably/lib/objects/integration/setup/IntegrationTest.kt:87-89
Timestamp: 2025-06-06T09:28:12.298Z
Learning: The Sandbox.kt file in ably-java live-objects module already has comprehensive HTTP retry mechanism using HttpRequestRetry with 5 retries, exponential backoff, and automatic retry on non-success responses and timeout exceptions.

lib/src/main/java/io/ably/lib/objects/type/LiveObjectUpdate.java (6)

Learnt from: sacOO7
PR: #1106
File: live-objects/src/main/kotlin/io/ably/lib/objects/serialization/Serialization.kt:25-29
Timestamp: 2025-06-23T14:18:25.315Z
Learning: In the ably-java codebase, the DefaultLiveObjectSerializer class methods like writeMsgpackArray will have their type signatures updated to be non-nullable since the calling sites ensure objects are never null when passed to these methods.

Learnt from: sacOO7
PR: #1092
File: live-objects/src/test/kotlin/io/ably/lib/objects/TestUtils.kt:21-32
Timestamp: 2025-06-03T09:15:15.338Z
Learning: In test utility code for the Ably Java Live Objects module, the team prefers to keep reflection-based field access utilities simple without additional error handling, allowing tests to fail fast if incorrect field names are used.

Learnt from: sacOO7
PR: #1085
File: lib/src/main/java/io/ably/lib/objects/LiveObjects.java:0-0
Timestamp: 2025-05-20T13:12:19.013Z
Learning: The LiveObjects interface does not currently include public API methods for resource management (dispose) or change listeners, as these features are not yet implemented.

Learnt from: sacOO7
PR: #1106
File: live-objects/src/main/kotlin/io/ably/lib/objects/serialization/Serialization.kt:38-46
Timestamp: 2025-06-23T14:14:17.847Z
Learning: In the ably-java codebase, the DefaultLiveObjectSerializer class uses intentional unsafe casting (objects as Array<ObjectMessage>) without type validation in both writeMsgpackArray and asJsonArray methods. This is a deliberate design decision to keep the dynamically-loaded class simple and let ClassCastException occur naturally for type mismatches.

Learnt from: sacOO7
PR: #1087
File: lib/src/main/java/io/ably/lib/objects/LiveObjectsAdapter.java:32-34
Timestamp: 2025-05-27T12:11:25.084Z
Learning: In LiveObjects implementation (lib/src/main/java/io/ably/lib/objects/LiveObjectsAdapter.java), the send method intentionally hardcodes queueEvents to true rather than respecting ably.options.queueMessages. This is because LiveObjects requires reliable message delivery to ensure proper state synchronization and acknowledgment, unlike other realtime components that may allow configurable queuing behavior.

Learnt from: sacOO7
PR: #1106
File: live-objects/src/main/kotlin/io/ably/lib/objects/serialization/MsgpackSerialization.kt:207-211
Timestamp: 2025-06-23T14:28:23.301Z
Learning: In the Ably Java LiveObjects MessagePack deserialization code, the action field in ObjectOperation is guaranteed to always be present in the protocol, so using a default value during deserialization is acceptable and won't mask real protocol errors.

live-objects/src/main/kotlin/io/ably/lib/objects/DefaultLiveObjects.kt (8)