events: A JavaScript repository from Seikho

Longshot Event Store API

Carl Winkler

Installation

npm install ls-events --save

Pre-requisites

Redis
This store uses Redis for its pub/sub and event storage.

Usage

All pub, sub and fetch methods return Promises.

Run your app with the --events hostname:port to pass in the Redis location.
If no runtime arguments are provided, 127.0.0.1:6379 are used as default.
This can be overridden with the setHost() function.

var events = require("ls-events");

// Subscribe to a pattern
events.psub("users/create/*", (ch, pt, msg) => {
	console.log("[CHANNEL: %s] Message: %s", ch, msg);
}).then(count => console.log("Successfully listening with %d others", count));

var newUser = {
	username: 'carl',
	email: 'carl@longshot.io',
	// ...
}
var newEvent = {
	event: 'create',
	context: 'users',
	key: 'carl', // Primary key of the object
	data: newUser
};

events.pub("users/create/carl", newEvent)
	.then(() => console.log("Successfully published!"));
// This will publish to the channel 'users/create/carl' (context/event/key)

/*
Console output:
>> Successfully listening with 1 others!
>> Successfully published!
>> [CHANNEL: users/create/carl] Message: { "usersname": "carl", "email": "carl@longshot.io" }
*/

API

Event

{
	event: string, // operation type. E.g. create, read, update, delete, ...
	context: string, // object type. E.g. users, orders, invoices, ...
	key: string|number, // identifier of the object. typically the primary key.
	data: any // a POJO. This will get serialised and deserialsed using JSON.
}

Configuration

Configure the location of Redis.
Defaults to 127.0.0.1 and port 6379

function setHost(hostname: string, port?: number);

Subscribing to a simple channel such as: users/create/carl

function sub(channel: string, callback: (channel: string, message: any) =>  void): Promise<{}>;

Pattern Subscribe

Subscribing to a event that conforms to a pattern, such as:

users/create/*
users/*/*
users/*/carl

// Pattern: The pattern that was subscribed to
// Channel: The fully qualified channel that was published to
// Message: The message received
function psub(channel: string, callback: (pattern: string, channel: string, message: any) =>  void): Promise<{}>;

Publish

Publish an event. See the Event type.
The publish function automatically constructs the channel from the Event object provided.

function pub(event: Event): Promise<{}>;

Fetch

Fetches events from the event store.
context: object type. Such as 'users', 'orders', ... event: type of event. Such as 'create', 'update', 'delete', ... key: the key of the object. Typically the primary key. In the previous example this would be 'carl'.

function fetch(context?: string, event?: string, key?: string): Promise<FetchResult[]>;

interface FetchResult {
    channel: string;
    published: number; // Date.now() when it the event was published
    data: any; // Object
}

Seikho/events