Ably

Ably is the platform that powers synchronized digital experiences in realtime. Whether attending an event in a virtual venue, receiving realtime financial information, or monitoring live car performance data – consumers simply expect realtime digital experiences as standard. Ably provides a suite of APIs to build, extend, and deliver powerful digital experiences in realtime for more than 250 million devices across 80 countries each month. Organizations like Bloomberg, HubSpot, Verizon, and Hopin depend on Ably’s platform to offload the growing complexity of business-critical realtime data synchronization at global scale. For more information, see the Ably documentation.

This is a Ruby client library for Ably. The library currently targets the Ably 2.0.0 client library specification. You can see the complete list of features this client library supports in our client library SDKs feature support matrix.

Supported platforms

This SDK supports Ruby 2.7 and 3.x. For eventmachine and Ruby 3.x note please visit Ruby 3.0 support section.

As of v1.1.5 this library requires libcurl as a system dependency. On most systems this is already installed but in rare cases where it isn't (for example debian-slim Docker images such as ruby-slim) you will need to install it yourself. On debian you can install it with the command sudo apt-get install libcurl4.

We regression-test the SDK against a selection of Ruby versions (which we update over time, but usually consists of mainstream and widely used versions). Please refer to .github/workflows/check.yml for the set of versions that currently undergo CI testing.

If you find any compatibility issues, please do raise an issue in this repository or contact Ably customer support for advice.

Documentation

Visit https://ably.com/documentation for a complete API reference and code examples.

Installation

The client library is available as a gem from RubyGems.org.

Add this line to your application's Gemfile:

gem 'ably'

And then install this Bundler dependency:

$ bundle

Or install it yourself as:

$ gem install ably

Using with Rails or Sinatra

This ably gem provides both a Realtime and REST version of the Ably library. Realtime depends on EventMachine to provide an asynchronous evented framework to run the library in, whereas the REST library depends only on synchronous libraries such as Faraday.

If you are using Ably within your Rails or Sinatra apps, more often than not, you probably want to use the REST only version of the library that has no dependency on EventMachine and provides a synchronous API that you will be used to using within Rails and Sinatra. See the REST only Ruby version of the Ably library.

Using the Realtime API

Introduction

All examples must be run within an EventMachine reactor as follows:

EventMachine.run do
  # ...
end

All examples assume a client has been created using one of the following:

# basic auth with an API key
client = Ably::Realtime.new(key: 'xxxxx')

# using token auth
client = Ably::Realtime.new(token: 'xxxxx')

If you do not have an API key, sign up for a free API key now

Connection

Successful connection:

client.connection.connect do
  # successful connection
end

Failed connection:

connection_result = client.connection.connect
connection_result.errback = Proc.new do
  # failed connection
end

Subscribing to connection state changes:

client.connection.on do |state_change|
  state_change.current #=> :connected
  state_change.previous #=> :connecting
end

Retrieve connection id, state etc

connection_id = client.connection.id
state = client.connection.state
recovery_key = client.connection.create_recovery_key # https://ably.com/docs/connect/states?q=recovery#connection-state-recover-options

Subscribing to a channel

Given a channel is created as follows:

channel = client.channels.get('test')

Subscribe to all events:

channel.subscribe do |message|
  message.name #=> "greeting"
  message.data #=> "Hello World!"
end

Only certain events:

channel.subscribe('myEvent') do |message|
  message.name #=> "myEvent"
  message.data #=> "myData"
end

Publishing a message to a channel

channel.publish('greeting', 'Hello World!')

Querying the History

channel.history do |messages_page|
  messages_page #=> #<Ably::Models::PaginatedResult ...>
  messages_page.items.first # #<Ably::Models::Message ...>
  messages_page.items.first.data # payload for the message
  messages_page.items.length # number of messages in the current page of history
  messages_page.next do |next_page|
    next_page #=> the next page => #<Ably::Models::PaginatedResult ...>
  end
  messages_page.has_next? # false, there are more pages
end

Presence on a channel

channel.presence.enter(data: 'metadata') do |presence|
  presence.get do |members|
    members #=> [Array of members present]
  end
end

Subscribing to presence events

channel.presence.subscribe do |member|
  member #=> { action: :enter, client_id: 'bob' }
end

Querying the Presence History

channel.presence.history do |presence_page|
  presence_page.items.first.action # Any of :enter, :update or :leave
  presence_page.items.first.client_id # client ID of member
  presence_page.items.first.data # optional data payload of member
  presence_page.next do |next_page|
    next_page #=> the next page => #<Ably::Models::PaginatedResult ...>
  end
  presence_page.has_next? # false, there are more pages
end

Symmetric end-to-end encrypted payloads on a channel

When a 128 bit or 256 bit key is provided to the library, all payloads are encrypted and decrypted automatically using that key on the channel. The secret key is never transmitted to Ably and thus it is the developer's responsibility to distribute a secret key to both publishers and subscribers.

secret_key = Ably::Util::Crypto.generate_random_key
channel = client.channels.get('test', cipher: { key: secret_key })
channel.subscribe do |message|
  message.data #=> "sensitive data (encrypted before being published)"
end
channel.publish "name (not encrypted)", "sensitive data (encrypted before being published)"

Using the REST API

Introduction

Unlike the Realtime API, all calls are synchronous and are not run within EventMachine.

All examples assume a client and/or channel has been created as follows:

client = Ably::Rest.new(key: 'xxxxx')
channel = client.channel('test')

Publishing a message to a channel

channel.publish('myEvent', 'Hello!') #=> true

Querying the History

messages_page = channel.history #=> #<Ably::Models::PaginatedResult ...>
messages_page.items.first #=> #<Ably::Models::Message ...>
messages_page.items.first.data # payload for the message
messages_page.next # retrieves the next page => #<Ably::Models::PaginatedResult ...>
messages_page.has_next? # false, there are more pages

Current presence members on a channel

members_page = channel.presence.get # => #<Ably::Models::PaginatedResult ...>
members_page.items.first # first member present in this page => #<Ably::Models::PresenceMessage ...>
members_page.items.first.client_id # client ID of first member present
members_page.next # retrieves the next page => #<Ably::Models::PaginatedResult ...>
members_page.has_next? # false, there are more pages

Querying the presence history

presence_page = channel.presence.history #=> #<Ably::Models::PaginatedResult ...>
presence_page.items.first #=> #<Ably::Models::PresenceMessage ...>
presence_page.items.first.client_id # client ID of first member
presence_page.next # retrieves the next page => #<Ably::Models::PaginatedResult ...>

Symmetric end-to-end encrypted payloads on a channel

When a 128 bit or 256 bit key is provided to the library, all payloads are encrypted and decrypted automatically using that key on the channel. The secret key is never transmitted to Ably and thus it is the developer's responsibility to distribute a secret key to both publishers and subscribers.

secret_key = Ably::Util::Crypto.generate_random_key
channel = client.channels.get('test', cipher: { key: secret_key })
channel.publish nil, "sensitive data" # data will be encrypted before publish
messages_page = channel.history
messages_page.items.first.data #=> "sensitive data"

Generate a Token

Tokens are issued by Ably and are readily usable by any client to connect to Ably:

token_details = client.auth.request_token
# => #<Ably::Models::TokenDetails ...>
token_details.token # => "xVLyHw.CLchevH3hF....MDh9ZC_Q"
client = Ably::Rest.new(token: token_details)

Generate a TokenRequest

Token requests are issued by your servers and signed using your private API key. This is the preferred method of authentication as no secrets are ever shared, and the token request can be issued to trusted clients without communicating with Ably.

token_request = client.auth.create_token_request(ttl: 3600, client_id: 'jim')
# => {"id"=>...,
#     "clientId"=>"jim",
#     "ttl"=>3600,
#     "timestamp"=>...,
#     "capability"=>"{\"*\":[\"*\"]}",
#     "nonce"=>...,
#     "mac"=>...}

client = Ably::Rest.new(token: token_request)

Fetching your application's stats

stats_page = client.stats #=> #<Ably::Models::PaginatedResult ...>
stats_page.items.first = #<Ably::Models::Stats ...>
stats_page.next # retrieves the next page => #<Ably::Models::PaginatedResult ...>

Fetching the Ably service time

client.time #=> 2013-12-12 14:23:34 +0000

Ruby 3.0 support

If you cannot install ably realtime gem because of eventmachine openssl problems, please try to set your openssl-dir, i.e.:

gem install eventmachine -- --with-openssl-dir=/usr/local/opt/[email protected]

More about eventmachine and ruby 3.0 support here https://github.com/eventmachine/eventmachine/issues/932

Dependencies

If you only need to use the REST features of this library and do not want EventMachine as a dependency, then you should consider using the Ably Ruby REST gem.

Upgrading from an older version

• Release and upgrade notes for v0.8 -> v1.0

Support, feedback and troubleshooting

Please visit https://ably.com/support for access to our knowledgebase and to ask for any assistance.

You can also view the community reported Github issues.

To see what has changed in recent versions of Bundler, see the CHANGELOG.

Contributing

1. Fork it
2. When pulling to local, make sure to also pull the ably-common repo (git submodule init && git submodule update)
3. Create your feature branch (git checkout -b my-new-feature)
4. Commit your changes (git commit -am 'Add some feature')
5. Ensure you have added suitable tests and the test suite is passing(bundle exec rspec)
6. Push to the branch (git push origin my-new-feature)
7. Create a new Pull Request

Release process

This library uses semantic versioning. For each release, the following needs to be done:

1. Create a branch for the release, named like release/1.2.3 (where 1.2.3 is the new version number)
2. Update the version number in version.rb and commit the change.
3. Run github_changelog_generator to automate the update of the CHANGELOG. This may require some manual intervention, both in terms of how the command is run and how the change log file is modified. Your mileage may vary:
   • The command you will need to run will look something like this: github_changelog_generator -u ably -p ably-ruby --since-tag v1.2.3 --output delta.md --token $GITHUB_TOKEN_WITH_REPO_ACCESS. Generate token here.
   • Using the command above, --output delta.md writes changes made after --since-tag to a new file
   • The contents of that new file (delta.md) then need to be manually inserted at the top of the CHANGELOG.md, changing the "Unreleased" heading and linking with the current version numbers
   • Also ensure that the "Full Changelog" link points to the new version tag instead of the HEAD
4. Commit this change: git add CHANGELOG.md && git commit -m "Update change log."
5. Ideally, run rake doc:spec to generate a new spec file. Then commit these changes.
6. Make a PR against main. Once the PR is approved, merge it into main.
7. Add a tag to the new main head commit and push to origin such as git tag v1.0.3 && git push origin v1.0.3.
8. Visit https://github.com/ably/ably-ruby/tags and Add release notes for the release including links to the changelog entry.
9. Run rake release to publish the gem to Rubygems.
10. Release the REST-only library ably-ruby-rest.
11. Create the entry on the Ably Changelog (via headwayapp).