pusher-platform.js

This is the official Pusher Platform client library for web browsers. Use it to build SDKs for services running on Pusher Platform / Elements infrastructure.

Issues, Bugs, and Feature Requests

Feel free to create an issue on GitHub if you find anything wrong. Please use the existing template. If you wish to contribute, please make a pull request. To summon help you can also ping @pusher/sigsdk or @zmarkan.

Installation

We assume you use yarn/npm in your development workflow. You can grab it from the yarn/npm repository:

yarn add 'pusher-platform'

The latest working version will always be published there.

If you like to live dangerously, you can check in the Releases tab on Github for the latest release, or clone a local version and refer to it using a relative path.

Importing

We assume you use Webpack or something similar:

Currently there are two ways to import it - either import the whole thing:

Browser

import PusherPlatform from 'pusher-platform';

let instance = new PusherPlatform.Instance(...);

React Native

import PusherPlatform from 'pusher-platform/react-native';

let instance = new PusherPlatform.Instance(...);

Or import individual components. Currently you can access:

• Instance
• BaseClient
• Subscription

Browser

import { Instance, ... } from 'pusher-platform';

let instance = new Instance(...);

React Native

import { Instance, ... } from 'pusher-platform/react-native';

let instance = new Instance(...);

Usage and Features

Instance

This is the main entry point - represents a single instance of a service running on the Elements infrastructure. Initialise with an InstanceOptions object that MUST contain at least the locator, serviceName, and serviceVersion.

InstanceOptions:

  serviceName: string; //Mandatory
  locator: string; // Mandatory
  serviceVersion: string //Mandatory

  host?: string; // Use in debugging, overrides the cluster setting that is the part of `locator`
  encrypted?: boolean; // Defaults to true

  client?: BaseClient; // You can provide custom implementation - this will probably be deprecated in the future
  logger?: Logger; // You can provide custom implementation. Defaults to ConsoleLogger(2) - logging anything non-verbose (level debug and above)

It has 3 methods of interest:

• request(options: RequestOptions): Promise<any>

For regular HTTP requests. Relays to BaseClient.

RequestOptions:

export interface RequestOptions {
  method: string;
  path: string;
  jwt?: string;
  headers?: ElementsHeaders;
  body?: any;
  logger?: Logger;
  tokenProvider?: TokenProvider;
}

request(options: RequestOptions, tokenParams?: any): Promise

• subscribeNonResuming(options: SubscribeOptions)

A subscription to events. Creates a SUBSCRIBE call using the base client. Returns Subscription

• subscribeResuming(options: ResumableSubscribeOptions)

Like a subscription, but allows you to specify a initialEventId that will return you all items from this ID. Example - Feeds. Returns Subscription.

BaseClient

This makes all the requests and executes them. They are standard XHR objects.

It also creates XHRs that are used to create instances of Subscription.

Subscription

SubscribeOptions:

export interface SubscribeOptions {
  path: string;
  headers?: ElementsHeaders;
  listeners: SubscriptionListeners;
  retryStrategyOptions?: RetryStrategyOptions;
  tokenProvider?: TokenProvider;
}

export interface SubscriptionListeners {
  onOpen?: (headers: ElementsHeaders) => void;
  onSubscribe?: () => void;
  onRetrying?:() => void;
  onEvent?: (event: SubscriptionEvent) => void;
  onError?: (error: any) => void;
  onEnd?: (error: any) => void;
}

There are standard callbacks for different subscription events onOpen, onEvent, onEnd, and onError. There are also helper callbacks onRetrying and onSubscribe that can be used to inform developers when a subscription has been lost or re-established.

Use unsubscribe() to close this subscription.

Subscription and Resumable Subscription

Options:

export interface SubscribeOptions {
  path: string;
  headers?: ElementsHeaders;
  listeners: SubscriptionListeners;
  retryStrategyOptions?: RetryStrategyOptions;
  tokenProvider?: TokenProvider;
}

export interface ResumableSubscribeOptions extends SubscribeOptions {
  initialEventId?: string;
}

Listeners:

export interface SubscriptionListeners {
  onOpen?: (headers: ElementsHeaders) => void; // Triggered once per subscription
  onSubscribe?: () => void; // Triggered each time a subscription is established
  onRetrying?:() => void; // Triggered each time we are retrying to connect
  onEvent?: (event: SubscriptionEvent) => void; // Triggered for each event
  onError?: (error: any) => void; // Triggered once. Ends session
  onEnd?: (error: any) => void; // Triggered once.
}

Token Provider:

export interface TokenProvider {
  fetchToken(tokenParams?: any): Promise<string>;
  clearToken(token?: string): void;
}

• tokenParams can be anything, and is optional. Some services might require it.
• clearToken allows you to "forget" an expired token in the current token provider

Retry Strategy:

export interface RetryStrategyOptions {
  initialTimeoutMillis?:  number, //Defaults to 1000
  maxTimeoutMillis?: number, //Defaults to 5000
  limit?: number, //Defaults to -1 (unlimited). Set to 0 to disable retrying.
  increaseTimeout?: (currentTimeout: number) => number; //Defaults to currentTimeout*2 or maxTimeoutMillis
}

Logger

It logs things. Interface:

export interface Logger {
  verbose(message: string, error?: Error): void;
  debug(message: string, error?: Error): void;
  info(message: string, error?: Error): void;
  warn(message: string, error?: Error): void;
  error(message: string, error?: Error): void;
}

You can pass it to the Instance object at startup. The default implementation is the ConsoleLogger. You initiate it with a threshold for the log level (defaults to LogLevel.DEBUG). It will log everything at or above this log level.

The default log levels are:

export enum LogLevel {
  VERBOSE = 1,
  DEBUG = 2,
  INFO = 3,
  WARNING = 4,
  ERROR = 5
}

TokenProvider

This is up to the service implementer to implement.

export interface TokenProvider {
  fetchToken(tokenParams?: any): Promise<string>;
  clearToken(token?: string): void;
}

Building

yarn install
yarn build  # builds both web and react-native versions in dist/

This will create dist/web/pusher-platform.js as the main library.

Testing

We have 2 types of tests - unit and integration.

yarn test-jest for unit tests

Integration testing is trickier as it requires a testing service to be running. Currently it runs locally on your machine but this will eventually be deployed behind the Elements bridge.

The repository for it is here, and it requires a working Go installation. Then hopefully just run from the main directory of that test library:

glide install
./scripts/build
./scripts/run

Then run tests (from this dir): yarn test-integration. This will run tests and watch the src/ and test/ dirs to rebuild every time a file is changed. Good for development.

Once we have some sort of CI setup we'll be able to run just yarn test to get everything going and run just once.

Formatting and linting

Prettier and TSLint are used to keep the code formatted and linted nicely.

To format your code using Prettier, run:

yarn format

To lint your code using TSLint, run:

yarn lint

Please ensure that your code is formatted and linted before merging it into master.

License

pusher-platform-js is released under the MIT license. See LICENSE for details.