[ttypic]

The 2.0.0 release makes it clear what to use on a device and what to use on a server. The SDK is now split by where your code runs. Depend on io.ably.pubsub:device for code that runs on an end user's device, such as an Android app or a desktop client, or io.ably.pubsub:server for code that runs on your own infrastructure. Each artifact offers only the clients that make sense on its side. The artifact names are also what coding assistants see in the dependency declaration and the builder call, so they get the choice right too.

v2 also removes the APIs and client options deprecated in v1.

Below is an overview of the major changes in this release.

Please refer to the upgrade guide for the full details, including a list of all breaking changes and instructions on how to address them.

Per-side artifacts

This repository no longer publishes io.ably:ably-java or io.ably:ably-android. Depend on exactly one artifact, for the side of the connection your code runs on:

• io.ably.pubsub:device for code that runs on an end user's device: an Android app or a JVM desktop client. It is a Kotlin Multiplatform artifact; Maven consumers depend on io.ably.pubsub:device-jvm directly.
• io.ably.pubsub:server for code that runs on infrastructure you operate. It offers both a realtime client, PubSubRealtimeClient, and an HTTP client, PubSubHttpClient.

Clients are created through builders instead of constructors: PubSubDevice.clientBuilder() from io.ably.pubsub:device, and PubSubServer.realtimeClientBuilder() and PubSubServer.httpClientBuilder() from io.ably.pubsub:server. build() hands the client a shallow copy of the options, so a builder can be reused without affecting clients already built.

Never depend on io.ably.pubsub:core or io.ably.pubsub:core-android directly. The remaining artifacts change group only and release in lockstep at the same version: liveobjects, network-client-core, network-client-default, network-client-okhttp and pubsub-adapter move from io.ably to io.ably.pubsub.

Client API naming

• Packages move from io.ably.lib.* to io.ably.pubsub.*.
• AblyRealtime is renamed PubSubRealtimeClient and AblyRest is renamed PubSubHttpClient.
• Rest is renamed Http across the public API: io.ably.lib.rest.* moves to io.ably.pubsub.http.*, RestAnnotations is now HttpAnnotations, AblyBase is now PubSubBase and io.ably.lib.http.Http is now HttpRequester.
• Log tags are class names, so they change with the packages.

Server clients and authentication

• Requests identify as ably-pubsub-java/<version> instead of ably-java/<version> in the Ably-Agent header and the realtime agent parameter, with an ably-pubsub-server or ably-pubsub-device entry for the side.
• Clients from PubSubServer declare themselves as servers. Authenticate them with an API key. A realtime connection with token authentication needs a token carrying the signed x-ably-clientType=server claim (today a JWT), otherwise it is rejected with error 40167.
• When Ably asks a connected client to re-authenticate, the client emits UPDATE once renewAuth completes instead of before it has finished.

Push notifications

• The Android push registration token type is persisted by name instead of by enum ordinal. A stored FCM token is migrated; a stored GCM token is discarded and the device registers with FCM again.

Removed APIs

• The environment, restHost, realtimeHost and fallbackHostsUseDefault client options are removed in favour of endpoint. The default host moves to main.realtime.ably.net, so networks that restrict outbound traffic must allow *.realtime.ably.net and *.fallback.ably-realtime.com.
• The AblyRealtime and AblyRest constructors, the CompletionListener publish overloads, Connection.recoveryKey, the ConnectionState-keyed Connection event methods, Channel.sync(), Auth.authorise, Auth.renew, ChannelOptions.fromCipherKey, TokenDetails.fromJSON, TokenRequest.fromJSON and RegistrationToken.Type.GCM are removed.
• Channels.release() throws a checked AblyException (90011) unless the channel is INITIALIZED, DETACHED or FAILED.

Supported platforms changes

• Support for Android API levels lower than 24 has been dropped.

Summary by CodeRabbit

• Documentation
  • Updated the 2.0.0 changelog with its release date, links to the release and full changelog, and a migration overview.
  • The overview summarizes changes to artifacts, clients, builders, package and API names, server identity and authentication, re-authentication events, push-token persistence, removed APIs and options, the default host, and the minimum Android version.

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Walkthrough

The 2.0.0 changelog entry is dated 2026-10-30 and replaces the unreleased migration-guide summary with release notes covering artifacts and clients, API and package changes, authentication, push-token persistence, removed APIs and options, host changes, and the Android API 24 minimum.

Changes

2.0.0 release changelog

Layer / File(s)	Summary
Document 2.0.0 changes CHANGELOG.md	The dated release entry describes artifacts, clients, API changes, authentication, push-token persistence, removed APIs and options, host changes, and the Android API 24 minimum. It links to the release tag and full changelog.

Priority: Normal

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Feature

Possibly related issues

• ably/ably-pubsub-java#1255 The changelog documents the checked Channels.release() exception described in the issue.

Possibly related PRs

• ably/ably-pubsub-java#1256 Both PRs update the 2.0.0 changelog with builder behavior and shallow option copying.
• ably/ably-pubsub-java#1245 This PR introduces the 2.0.0 artifacts, builders, agent identifiers, and constructor deprecations that the changelog describes.
• ably/ably-pubsub-java#1251 This PR implements the Channels.release() checked exception documented in the changelog.

Suggested reviewers: sacoo7

Merge Risk: Minimal · up to 78094

The release-note update has no identified merge-blocking issue and is ready to merge after normal checks.

Pre-merge checks: 5

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title, "Release 2.0.0," accurately identifies the main change: documenting the 2.0.0 release and its breaking changes.
Docstring Coverage		No eligible functions found in the changed files. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentat…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

No eligible functions found in the changed files. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 0 functions across 0 files. (1 skipped: 1 unsupported.)

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