pusher

README

Pusher HTTP Go Library

The Golang library for interacting with the Pusher HTTP API.

This package lets you trigger events to your client and query the state of your Pusher channels. When used with a server, you can validate Pusher webhooks and authenticate private- or presence-channels.

In order to use this library, you need to have a free account on http://pusher.com. After registering, you will need the application credentials for your app.

###Table of Contents

• Installation
• Getting Started
• Configuration
  • Additional options
  • Google App Engine
• Usage
  • Triggering events
  • Excluding event recipients
  • Authenticating Channels
  • Application state
  • Webhook validation
• Feature Support
• Developing the Library
  • Running the tests
• License

Installation

$ go get github.com/pusher/pusher-http-go

Getting Started

package main

import "github.com/pusher/pusher-http-go"

func main(){

	// instantiate a client
	client := pusher.Client{
	  AppId: "your_app_id",
	  Key: "your_app_key",
	  Secret: "your_app_secret",
	}

	data := map[string]string{"message": "hello world"}

	// trigger an event on a channel, along with a data payload
	client.Trigger("test_channel", "my_event", data)

}

Configuration

The easiest way to configure the library is by creating a new Pusher instance:

client := pusher.Client{
  AppId: "your_app_id",
  Key: "your_app_key",
  Secret: "your_app_secret",
}

Additional options

Instantiation From URL

client := pusher.ClientFromURL("http://key:secret@api.pusherapp.com/apps/app_id")

Instantiation From Environment Variable

client := pusher.ClientFromEnv("PUSHER_URL")

This is particularly relevant if you are using Pusher as a Heroku add-on, which stores credentials in a "PUSHER_URL" environment variable.

HTTPS

To ensure requests occur over HTTPS, set the Secure property of a pusher.Client to true.

client.Secure = true

This is false by default.

Request Timeouts

If you wish to set a time-limit for each HTTP request, create a http.Client instance with your specified Timeout field and set it as the Pusher instance's Client:

httpClient := &http.Client{Timeout: time.Second * 3}

pusherClient.HttpClient = httpClient

If you do not specifically set a HTTP client, a default one is created with a timeout of 5 seconds.

Changing Host

Changing the pusher.Client's Host property will make sure requests are sent to your specified host.

client.Host = "foo.bar.com"

By default, this is "api.pusherapp.com".

Changing the Cluster

Setting the pusher.Client's Cluster property will make sure requests are sent to the cluster where you created your app.

*NOTE! Host option has precendece over the Cluster, ie. if Host is set then Cluster will be ignored.

client.Cluster = "eu" // in this case requests will be made to api-eu.pusher.com.

Google App Engine

As of version 1.0.0, this library is compatible with Google App Engine's urlfetch library. Simply pass in the HTTP client returned by urlfetch.Client to your Pusher initialization struct.

package helloworldapp

import (
	"appengine"
	"appengine/urlfetch"
	"fmt"
	"github.com/pusher/pusher-http-go"
	"net/http"
)

func init() {
	http.HandleFunc("/", handler)
}

func handler(w http.ResponseWriter, r *http.Request) {

	c := appengine.NewContext(r)
	urlfetchClient := urlfetch.Client(c)

	client := pusher.Client{
		AppId:  "app_id",
		Key:    "key",
		Secret: "secret",
		HttpClient: urlfetchClient,
	}

	client.Trigger("test_channel", "my_event", map[string]string{"message": "hello world"})

	fmt.Fprint(w, "Hello, world!")
}

Usage

Triggering events

It is possible to trigger an event on one or more channels. Channel names can contain only characters which are alphanumeric, _ or `-`` and have to be at most 200 characters long. Event name can be at most 200 characters long too.

Single channel

#####func (c *Client) Trigger

Argument	Description
channel string	The name of the channel you wish to trigger on.
event string	The name of the event you wish to trigger
data interface{}	The payload you wish to send. Must be marshallable into JSON.

data := map[string]string{"hello": "world"}
client.Trigger("greeting_channel", "say_hello", data)

Multiple channels

#####func (c. *Client) TriggerMulti

Argument	Description
channels []string	A slice of channel names you wish to send an event on. The maximum length is 10.
event string	As above.
data interface{}	As above.

######Example

client.TriggerMulti([]string{"a_channel", "another_channel"}, "event", data)

Excluding event recipients

func (c *Client) TriggerExclusive and func (c *Client) TriggerMultiExclusive follow the patterns above, except a socket_id is given as the last parameter.

These methods allow you to exclude a recipient whose connection has that socket_id from receiving the event. You can read more here.

######Examples

On one channel:

client.TriggerExclusive("a_channel", "event", data, "123.12")

On multiple channels:

client.TriggerMultiExclusive([]string{"a_channel", "another_channel"}, "event", data, "123.12")

Batches

#####func (c. *Client) TriggerBatch

Argument	Description
batch []Event	A list of events to publish

Example

client.TriggerBatch([]pusher.Event{
  { Channel: "a_channel", Name: "event", Data: "hello world", nil },
  { Channel: "a_channel", Name: "event", Data: "hi my name is bob", nil },
})

Authenticating Channels

Application security is very important so Pusher provides a mechanism for authenticating a user’s access to a channel at the point of subscription.

This can be used both to restrict access to private channels, and in the case of presence channels notify subscribers of who else is also subscribed via presence events.

This library provides a mechanism for generating an authentication signature to send back to the client and authorize them.

For more information see our docs.

Private channels

func (c *Client) AuthenticatePrivateChannel

Argument	Description
params []byte	The request body sent by the client

Return Value	Description
response []byte	The response to send back to the client, carrying an authentication signature
err error	Any errors generated

Example

func pusherAuth(res http.ResponseWriter, req *http.Request) {

	params, _ := ioutil.ReadAll(req.Body)
	response, err := client.AuthenticatePrivateChannel(params)

	if err != nil {
		panic(err)
	}

	fmt.Fprintf(res, string(response))
}

func main() {
	http.HandleFunc("/pusher/auth", pusherAuth)
	http.ListenAndServe(":5000", nil)
}

Example (JSONP)

func pusherJsonpAuth(res http.ResponseWriter, req *http.Request) {
	var (
		callback, params string
	)

	{
		q := r.URL.Query()
		callback = q.Get("callback")
		if callback == "" {
			panic("callback missing")
		}
		q.Del("callback")
		params = []byte(q.Encode())
	}

	response, err := client.AuthenticatePrivateChannel(params)
	if err != nil {
		panic(err)
	}

	res.Header().Set("Content-Type", "application/javascript; charset=utf-8")
	fmt.Fprintf(res, "%s(%s);", callback, string(response))
}

func main() {
	http.HandleFunc("/pusher/auth", pusherJsonpAuth)
	http.ListenAndServe(":5000", nil)
}

Authenticating presence channels

Using presence channels is similar to private channels, but in order to identify a user, clients are sent a user_id and, optionally, custom data.

func (c *Client) AuthenticatePresenceChannel

Argument	Description
params []byte	The request body sent by the client
member pusher.MemberData	A struct representing what to assign to a channel member, consisting of a UserId and any custom UserInfo. See below

Custom Types

pusher.MemberData

type MemberData struct {
    UserId   string
    UserInfo map[string]string
}

Example

params, _ := ioutil.ReadAll(req.Body)

presenceData := pusher.MemberData{
	UserId: "1",
	UserInfo: map[string]string{
		"twitter": "jamiepatel",
	},
}

response, err := client.AuthenticatePresenceChannel(params, presenceData)

if err != nil {
	panic(err)
}

fmt.Fprintf(res, response)

Application state

This library allows you to query our API to retrieve information about your application's channels, their individual properties, and, for presence-channels, the users currently subscribed to them.

Get the list of channels in an application

func (c *Client) Channels

Argument	Description
additionalQueries map[string]string	A map with query options. A key with "filter_by_prefix" will filter the returned channels. To get number of users subscribed to a presence-channel, specify an "info" key with value "user_count". Pass in nil if you do not wish to specify any query attributes.

Return Value	Description
channels *pusher.ChannelsList	A struct representing the list of channels. See below.
err error	Any errors encountered

Custom Types

pusher.ChannelsList

type ChannelsList struct {
    Channels map[string]ChannelListItem
}

pusher.ChannelsListItem

type ChannelListItem struct {
    UserCount int
}

######Example

channelsParams := map[string]string{
    "filter_by_prefix": "presence-",
    "info":             "user_count",
}

channels, err := client.Channels(channelsParams)

//channels=> &{Channels:map[presence-chatroom:{UserCount:4} presence-notifications:{UserCount:31}  ]}

Get the state of a single channel

func (c *Client) Channel

Argument	Description
name string	The name of the channel
additionalQueries map[string]string	A map with query options. An "info" key can have comma-separated vales of "user_count", for presence-channels, and "subscription_count", for all-channels. Note that the subscription count is not allowed by default. Please contact us if you wish to enable this. Pass in nil if you do not wish to specify any query attributes.

Return Value	Description
channel *pusher.Channel	A struct representing a channel. See below.
err error	Any errors encountered

######Custom Types

pusher.Channel

type Channel struct {
    Name              string
    Occupied          bool
    UserCount         int
    SubscriptionCount int
}

Example

channelParams := map[string]string{
	"info": "user_count,subscription_count",
}

channel, err := client.Channel("presence-chatroom", channelParams)

//channel=> &{Name:presence-chatroom Occupied:true UserCount:42 SubscriptionCount:42}

Get a list of users in a presence channel

func (c *Client) GetChannelUsers

Argument	Description
name string	The channel name

Return Value	Description
users *pusher.Users	A struct representing a list of the users subscribed to the presence-channel. See below
err error	Any errors encountered.

Custom Types

pusher.Users

type Users struct {
    List []User
}

pusher.User

type User struct {
    Id string
}

Example

users, err := client.GetChannelUsers("presence-chatroom")

//users=> &{List:[{Id:13} {Id:90}]}

Webhook validation

On your dashboard, you can set up webhooks to POST a payload to your server after certain events. Such events include channels being occupied or vacated, members being added or removed in presence-channels, or after client-originated events. For more information see https://pusher.com/docs/webhooks.

This library provides a mechanism for checking that these POST requests are indeed from Pusher, by checking the token and authentication signature in the header of the request.

func (c *Client) Webhook

Argument	Description
header http.Header	The header of the request to verify
body []byte	The body of the request

Return Value	Description
webhook *pusher.Webhook	If the webhook is valid, this method will return a representation of that webhook that includes its timestamp and associated events. If invalid, this value will be nil.
err error	If the webhook is invalid, an error value will be passed.

Custom Types

pusher.Webhook

type Webhook struct {
    TimeMs int
    Events []WebhookEvent
}

pusher.WebhookEvent

type WebhookEvent struct {
    Name     string
    Channel  string
    Event    string
    Data     string
    SocketId string
}

Example

func pusherWebhook(res http.ResponseWriter, req *http.Request) {

	body, _ := ioutil.ReadAll(req.Body)
	webhook, err := client.Webhook(req.Header, body)
  	if err != nil {
      fmt.Println("Webhook is invalid :(")
  	} else {
      fmt.Printf("%+v\n", webhook.Events)
  	}

}

Feature Support

Feature	Supported
Trigger event on single channel	✔
Trigger event on multiple channels	✔
Trigger events in batches	✔
Excluding recipients from events	✔
Authenticating private channels	✔
Authenticating presence channels	✔
Get the list of channels in an application	✔
Get the state of a single channel	✔
Get a list of users in a presence channel	✔
WebHook validation	✔
Heroku add-on support	✔
Debugging & Logging	✔
Cluster configuration	✔
Timeouts	✔
HTTPS	✔
HTTP Proxy configuration	✘
HTTP KeepAlive	✘

Helper Functionality

These are helpers that have been implemented to to ensure interactions with the HTTP API only occur if they will not be rejected e.g. channel naming conventions.

Helper Functionality	Supported
Channel name validation	✔
Limit to 10 channels per trigger	✔
Limit event name length to 200 chars	✔

Developing the Library

Feel more than free to fork this repo, improve it in any way you'd prefer, and send us a pull request :)

Running the tests

Simply type:

$ go test

License

This code is free to use under the terms of the MIT license.

Documentation

Overview

The Golang library for interacting with the Pusher HTTP API.

This package lets you trigger events to your client and query the state of your Pusher channels. When used with a server, you can validate Pusher webhooks and authenticate private- or presence-channels.

In order to use this library, you need to have a free account on http://pusher.com. After registering, you will need the application credentials for your app.

Getting Started

To create a new client, simply pass in your application credentials to a `pusher.Client` struct:

client := pusher.Client{
  AppId: "your_app_id",
  Key: "your_app_key",
  Secret: "your_app_secret",
}

To start triggering events on a channel, we simply call `client.Trigger`:

data := map[string]string{"message": "hello world"}

// trigger an event on a channel, along with a data payload
client.Trigger("test_channel", "event", data)

Read on to see what more you can do with this library, such as authenticating private- and presence-channels, validating Pusher webhooks, and querying the HTTP API to get information about your channels.

Author: Jamie Patel, Pusher

Index

• type BufferedEvents
• type Channel
• type ChannelListItem
• type ChannelsList
• type Client
  • func ClientFromEnv(key string) (*Client, error)
  • func ClientFromURL(url string) (*Client, error)
  • func (c *Client) AuthenticatePresenceChannel(params []byte, member MemberData) (response []byte, err error)
  • func (c *Client) AuthenticatePrivateChannel(params []byte) (response []byte, err error)
  • func (c *Client) Channel(name string, additionalQueries map[string]string) (*Channel, error)
  • func (c *Client) Channels(additionalQueries map[string]string) (*ChannelsList, error)
  • func (c *Client) GetChannelUsers(name string) (*Users, error)
  • func (c *Client) Trigger(channel string, eventName string, data interface{}) (*BufferedEvents, error)
  • func (c *Client) TriggerBatch(batch []Event) (*BufferedEvents, error)
  • func (c *Client) TriggerExclusive(channel string, eventName string, data interface{}, socketID string) (*BufferedEvents, error)
  • func (c *Client) TriggerMulti(channels []string, eventName string, data interface{}) (*BufferedEvents, error)
  • func (c *Client) TriggerMultiExclusive(channels []string, eventName string, data interface{}, socketID string) (*BufferedEvents, error)
  • func (c *Client) Webhook(header http.Header, body []byte) (*Webhook, error)
• type Event
• type MemberData
• type User
• type Users
• type Webhook
• type WebhookEvent

Types

type BufferedEvents

type BufferedEvents struct {
	EventIds map[string]string `json:"event_ids,omitempty"`
}

type Channel

type Channel struct {
	Name              string
	Occupied          bool `json:"occupied,omitempty"`
	UserCount         int  `json:"user_count,omitempty"`
	SubscriptionCount int  `json:"subscription_count,omitempty"`
}

Represents the information received about a channel from the Pusher API.

type ChannelListItem

type ChannelListItem struct {
	UserCount int `json:"user_count"`
}

An item of ChannelsList

type ChannelsList

type ChannelsList struct {
	Channels map[string]ChannelListItem `json:"channels"`
}

Represents a list of channels received by the Pusher API.

type Client

type Client struct {
	AppId      string
	Key        string
	Secret     string
	Host       string // host or host:port pair
	Secure     bool   // true for HTTPS
	Cluster    string
	HttpClient *http.Client
}

Client to the HTTP API of Pusher.

There easiest way to configure the library is by creating a new `Pusher` instance:

client := pusher.Client{
  AppId: "your_app_id",
  Key: "your_app_key",
  Secret: "your_app_secret",
}

To ensure requests occur over HTTPS, set the `Encrypted` property of a `pusher.Client` to `true`.

client.Secure = true // false by default

If you wish to set a time-limit for each HTTP request, set the `Timeout` property to an instance of `time.Duration`, for example:

client.Timeout = time.Second * 3 // set the timeout to 3 seconds - this is 5 seconds by default

Changing the `pusher.Client`'s `Host` property will make sure requests are sent to your specified host.

client.Host = "foo.bar.com" // by default this is "api.pusherapp.com".

func ClientFromEnv

func ClientFromEnv(key string) (*Client, error)

Alternatively, you can instantiate a client from an environment variable. This is particularly relevant if you are using Pusher as a Heroku add-on, which stores credentials in a `"PUSHER_URL"` environment variable. For example:

client := pusher.ClientFromEnv("PUSHER_URL")

func ClientFromURL

func ClientFromURL(url string) (*Client, error)

Clients can be instantiated from a specially-crafted Pusher URL. For example:

client := pusher.ClientFromURL("http://key:secret@api.pusherapp.com/apps/app_id")

func (*Client) AuthenticatePresenceChannel

func (c *Client) AuthenticatePresenceChannel(params []byte, member MemberData) (response []byte, err error)

Using presence channels is similar to private channels, but in order to identify a user, clients are sent a user_id and, optionally, custom data.

In this library, one does this by passing a `pusher.MemberData` instance.

params, _ := ioutil.ReadAll(req.Body)

presenceData := pusher.MemberData{
	UserId: "1",
	UserInfo: map[string]string{
		"twitter": "jamiepatel",
	},
}

response, err := client.AuthenticatePresenceChannel(params, presenceData)

if err != nil {
	panic(err)
}

fmt.Fprintf(res, response)

func (*Client) AuthenticatePrivateChannel

func (c *Client) AuthenticatePrivateChannel(params []byte) (response []byte, err error)

Application security is very important so Pusher provides a mechanism for authenticating a user’s access to a channel at the point of subscription.

This can be used both to restrict access to private channels, and in the case of presence channels notify subscribers of who else is also subscribed via presence events.

This library provides a mechanism for generating an authentication signature to send back to the client and authorize them.

For more information see our docs: http://pusher.com/docs/authenticating_users.

This is an example of authenticating a private-channel, using the built-in Golang HTTP library to start a server.

In order to authorize a client, one must read the response into type `[]byte` and pass it in. This will return a signature in the form of a `[]byte` for you to send back to the client.

func pusherAuth(res http.ResponseWriter, req *http.Request) {

	params, _ := ioutil.ReadAll(req.Body)
	response, err := client.AuthenticatePrivateChannel(params)

	if err != nil {
		panic(err)
	}

	fmt.Fprintf(res, string(response))

}

func main() {
	http.HandleFunc("/pusher/auth", pusherAuth)
	http.ListenAndServe(":5000", nil)
}

func (*Client) Channel

func (c *Client) Channel(name string, additionalQueries map[string]string) (*Channel, error)

Get the state of a single channel.

The parameter `additionalQueries` is a map with query options. An `"info"` key can have comma-separated vales of `"user_count"`, for presence-channels, and `"subscription_count"`, for all-channels. Note that the subscription count is not allowed by default. Please contact us at http://support.pusher.com if you wish to enable this. Pass in `nil` if you do not wish to specify any query attributes.

channelParams := map[string]string{
	"info": "user_count,subscription_count",
}

channel, err := client.Channel("presence-chatroom", channelParams)

//channel=> &{Name:presence-chatroom Occupied:true UserCount:42 SubscriptionCount:42}

func (*Client) Channels

func (c *Client) Channels(additionalQueries map[string]string) (*ChannelsList, error)

One can use this method to get a list of all the channels in an applicaiton.

The parameter `additionalQueries` is a map with query options. A key with `"filter_by_prefix"` will filter the returned channels. To get number of users subscribed to a presence-channel, specify an `"info"` key with value `"user_count"`. Pass in `nil` if you do not wish to specify any query attributes.

channelsParams := map[string]string{
    "filter_by_prefix": "presence-",
    "info":             "user_count",
}

channels, err := client.Channels(channelsParams)

//channels=> &{Channels:map[presence-chatroom:{UserCount:4} presence-notifications:{UserCount:31}  ]}

func (*Client) GetChannelUsers

func (c *Client) GetChannelUsers(name string) (*Users, error)

Get a list of users in a presence-channel by passing to this method the channel name.

users, err := client.GetChannelUsers("presence-chatroom")

//users=> &{List:[{Id:13} {Id:90}]}

func (*Client) Trigger

func (c *Client) Trigger(channel string, eventName string, data interface{}) (*BufferedEvents, error)

It is possible to trigger an event on one or more channels. Channel names can contain only characters which are alphanumeric, `_` or `-“ and have to be at most 200 characters long. Event name can be at most 200 characters long too.

Pass in the channel's name, the event's name, and a data payload. The data payload must be marshallable into JSON.

data := map[string]string{"hello": "world"}
client.Trigger("greeting_channel", "say_hello", data)

func (*Client) TriggerBatch

func (c *Client) TriggerBatch(batch []Event) (*BufferedEvents, error)

func (*Client) TriggerExclusive

func (c *Client) TriggerExclusive(channel string, eventName string, data interface{}, socketID string) (*BufferedEvents, error)

This method allow you to exclude a recipient whose connection has that `socket_id` from receiving the event. You can read more here: http://pusher.com/docs/duplicates.

client.TriggerExclusive("a_channel", "event", data, "123.12")

func (*Client) TriggerMulti

func (c *Client) TriggerMulti(channels []string, eventName string, data interface{}) (*BufferedEvents, error)

The same as `client.Trigger`, except one passes in a slice of `channels` as the first parameter. The maximum length of channels is 10.

client.TriggerMulti([]string{"a_channel", "another_channel"}, "event", data)

func (*Client) TriggerMultiExclusive

func (c *Client) TriggerMultiExclusive(channels []string, eventName string, data interface{}, socketID string) (*BufferedEvents, error)

Excluding a recipient on a trigger to multiple channels.

client.TriggerMultiExclusive([]string{"a_channel", "another_channel"}, "event", data, "123.12")

func (*Client) Webhook

func (c *Client) Webhook(header http.Header, body []byte) (*Webhook, error)

On your dashboard at http://app.pusher.com, you can set up webhooks to POST a payload to your server after certain events. Such events include channels being occupied or vacated, members being added or removed in presence-channels, or after client-originated events. For more information see https://pusher.com/docs/webhooks.

This library provides a mechanism for checking that these POST requests are indeed from Pusher, by checking the token and authentication signature in the header of the request.

If the webhook is valid, a `*pusher.Webhook* will be returned, and the `err` value will be nil. If it is invalid, the first return value will be nil, and an error will be passed.

func pusherWebhook(res http.ResponseWriter, req *http.Request) {

	body, _ := ioutil.ReadAll(req.Body)
	webhook, err := client.Webhook(req.Header, body)
  	if err != nil {
      fmt.Println("Webhook is invalid :(")
  	} else {
      fmt.Printf("%+v\n", webhook.Events)
  	}

}

type Event

type Event struct {
	Channel  string  `json:"channel"`
	Name     string  `json:"name"`
	Data     string  `json:"data"`
	SocketId *string `json:"socket_id,omitempty"`
}

type MemberData

type MemberData struct {
	UserId   string            `json:"user_id"`
	UserInfo map[string]string `json:"user_info,omitempty"`
}

A struct representing what to assign to a channel member, consisting of a `UserId` and any custom `UserInfo`.

type User

type User struct {
	Id string `json:"id"`
}

Represents a user and contains their ID.

type Users

type Users struct {
	List []User `json:"users"`
}

Represents a list of users in a presence-channel

type Webhook

type Webhook struct {
	TimeMs int            `json:"time_ms"` // the timestamp of the request
	Events []WebhookEvent `json:"events"`  // the events associated with the webhook
}

This is a parsed form of a valid webhook received by the server.

type WebhookEvent

type WebhookEvent struct {
	Name     string `json:"name"`                // the type of the event
	Channel  string `json:"channel"`             // the channel on which it was sent
	Event    string `json:"event,omitempty"`     // the name of the event
	Data     string `json:"data,omitempty"`      // the data associated with the event
	SocketId string `json:"socket_id,omitempty"` // the socket_id of the sending socket
	UserId   string `json:"user_id,omitempty"`   // the user_id of a member who has joined or vacated a presence-channel
}