ably / Ably Go

Ably Go

A Go client library for www.ably.io, the realtime messaging service.

Installation

~ $ go get -u github.com/ably/ably-go/ably

Feature support

This library implements the Ably REST and Realtime client APIs.

REST API

In respect of the Ably REST API, this library targets the Ably 1.1 client library specification, with some omissions as follows (see the client library specification for specification references):

It is intended that this library is upgraded incrementally, with 1.1 feature support expanded in successive minor releases. If there are features that are currently missing that are a high priority for your use-case then please contact Ably customer support. Pull Requests are also welcomed.

Realtime API

In respect of the Realtime API, this is an early experimental implementation that targets the (now superseded) 0.8 library specification. This means that there are significant shortfalls in functionality; the principal issues are:

• there is no channel suspended state; this means that the client will not automatically reattach to channels if a connection becomes suspended and then resumes, and presence members associated with the client will not be automatically re-entered;

• transient realtime publishing is not supported, so a call to publish() on a realtime channel will trigger attachment of the channel;

• inband reauthentication is not supported; expiring tokens will trigger a disconnection and resume of a realtime connection.

As with the REST API, it is intended that this library is upgraded incrementally and brought into line with the 1.1 specification. If there are features that are currently missing that are a high priority for your use-case then please contact Ably customer support. Pull Requests are also welcomed.

Using the Realtime API

Creating a client

client, err := ably.NewRealtimeClient(ably.NewClientOptions("xxx:xxx"))
if err != nil {
	panic(err)
}

channel := client.Channels.Get("test")

Subscribing to a channel for all events

sub, err := channel.Subscribe()
if err != nil {
	panic(err)
}

for msg := range sub.MessageChannel() {
	fmt.Println("Received message:", msg)
}

Subscribing to a channel for EventName1 and EventName2 events

sub, err := channel.Subscribe("EventName1", "EventName2")
if err != nil {
	panic(err)
}

for msg := range sub.MessageChannel() {
	fmt.Println("Received message:", msg)
}

Publishing to a channel

// send request to a server
res, err := channel.Publish("EventName1", "EventData1")
if err != nil {
	panic(err)
}

// await confirmation
if err = res.Wait(); err != nil {
	panic(err)
}

Announcing presence on a channel

// send request to a server
res, err := channel.Presence.Enter("presence data")
if err != nil {
	panic(err)
}

// await confirmation
if err = res.Wait(); err != nil {
	panic(err)
}

Announcing presence on a channel on behalf of other client

// send request to a server
res, err := channel.Presence.EnterClient("clientID", "presence data")
if err != nil {
	panic(err)
}

// await confirmation
if err = res.Wait(); err != nil {
	panic(err)
}

Getting all clients present on a channel

clients, err := channel.Presence.Get(true)
if err != nil {
	panic(err)
}

for _, client := range clients {
	fmt.Println("Present client:", client)
}

Subscribing to all presence messages

sub, err := channel.Presence.Subscribe()
if err != nil {
	panic(err)
}

for msg := range sub.PresenceChannel() {
	fmt.Println("Presence event:", msg)
}

Subscribing to 'Enter' presence messages only

sub, err := channel.Presence.Subscribe(proto.PresenceEnter)
if err != nil {
	panic(err)
}

for msg := range sub.PresenceChannel() {
	fmt.Println("Presence event:", msg)
}

Using the REST API

Introduction

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

client, err := ably.NewRestClient(ably.NewClientOptions("xxx:xxx"))
if err != nil {
	panic(err)
}

channel := client.Channels.Get("test", nil)

Publishing a message to a channel

err = channel.Publish("HelloEvent", "Hello!")
if err != nil {
	panic(err)
}

Querying the History

page, err := channel.History(nil)
for ; err == nil; page, err = page.Next() {
	for _, message := range page.Messages() {
		fmt.Println(message)
	}
}
if err != nil {
	panic(err)
}

Presence on a channel

page, err := channel.Presence.Get(nil)
for ; err == nil; page, err = page.Next() {
	for _, presence := range page.PresenceMessages() {
		fmt.Println(presence)
	}
}
if err != nil {
	panic(err)
}

Querying the Presence History

page, err := channel.Presence.History(nil)
for ; err == nil; page, err = page.Next() {
	for _, presence := range page.PresenceMessages() {
		fmt.Println(presence)
	}
}
if err != nil {
	panic(err)
}

Generate Token and Token Request

client.Auth.RequestToken()
client.Auth.CreateTokenRequest()

Fetching your application's stats

page, err := client.Stats(&ably.PaginateParams{})
for ; err == nil; page, err = page.Next() {
	for _, stat := range page.Stats() {
		fmt.Println(stat)
	}
}
if err != nil {
	panic(err)
}

Known limitations (work in progress)

As the library is actively developed couple of features are not there yet:

• Realtime connection recovery is not implemented
• Realtime connection failure handling is not implemented
• ChannelsOptions and CipherParams are not supported when creating a Channel
• Realtime Ping function is not implemented

Release process

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

• Create a branch for the release, named like release/1.1.6
• Replace all references of the current version number with the new version number and commit the changes
• 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-go --since-tag v1.1.4 --output delta.md
  • 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
  • Commit this change: git add CHANGELOG.md && git commit -m "Update change log."
• Commit CHANGELOG
• Make a PR against main
• Once the PR is approved, merge it into main
• Add a tag to the new main head commit and push to origin such as git tag v1.1.6 && git push origin v1.1.6

Support and feedback

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

You can also view the community reported Github issues.

Contributing

Because this package uses internal packages, all fork development has to happen under $GOPATH/src/github.com/ably/ably-go to prevent use of internal package not allowed errors.

1. Fork github.com/ably/ably-go
2. go to the ably-go directory: cd $GOPATH/src/github.com/ably/ably-go
3. add your fork as a remote: git remote add fork [email protected]:your-username/ably-go
4. create your feature branch: git checkout -b my-new-feature
5. commit your changes (git commit -am 'Add some feature')
6. ensure you have added suitable tests and the test suite is passing for both JSON and MessagePack protocols by running scripts/test.sh.
7. push to the branch: git push fork my-new-feature
8. create a new Pull Request