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Databridges JavaScript Dedicated Worker Wrapper for browsers

Databridges JavaScript Dedicated Worker Wrapper allows you to run dataBridges library instance in the background without affecting the performance of the web page application.

Download source

GitHub-Mark-32px Source is available in https://github.com/databridges-io/boilerplate.js.webworkers

Usage Overview

The following topics are covered:

Supported platforms

Safari Firefox Chrome Edge Opera Firefox Android Chrome Android Opera Android
4+ 3.5+ 4+ 12+ 10.6+ 4+ 18+ 11+

Initialization

Just start the dataBridges Dedicated Worker JavaScript file into your JavaScript code as shown below. 

dbWebWorker = new Worker("dbridgesDedicatedWorker.js");

You need to replace appkey and auth_url with the actual URL and Application Key in the dbridgesDedicatedWorker.js file in below section.

// Replace your dataBrdiges Application Key and Authentication URL below.
const dbApplnKey = 'appkey';
const dbAuthURL = 'auth_url';
Properties Description
auth_url (string) Authentication url from dataBridges dashboard.
appkey (string) Application Key from dataBridges dashboard.

How to Use

To make the coding readable we will be using below structure. This will be used for defining both sending and receiving messages from and to Web Workers. Each event types will have different sets of parameters along with the event types.

NOTE : You can enhance dbridgesDedicatedWorker.js this file depending on your requirement. This file helps you get started with basic functionality of dataBridges network library.

const workerEvents = {
    subscribe: 1,
    publish: 2,
    unsubscribe: 3,
    channelList: 4,
    dbStatus: 11,
    dbLog: 12,  
    event: 16,
}
Define event handling for Web Worker, This is the code which receives events from dbridgesDedicatedWorker.js. 

dbWebWorker.onmessage = function (e) {
    const recdData = e.data;
    switch (recdData.cmd) {
        case workerEvents.dbStatus:
            // Databridge connection status.
            // recdData.msg will have dataBridges Offline/Online status whenever they are changed
            console.log('dataBridges Connection Status :',recdData.msg);
            break;
        case workerEvents.dbLog:
            // Log messages recieved from WebWorker
            // Logs on dataBridges Events and other errors if any as and when generated.
            console.log(recdData.msg, recdData.err != '' ? 'Error : ' + recdData.err:'');
            break;
        case workerEvents.channelList:
            // Client List received from WebWorker
            // List of channels subscirbed by current browser connect. The result is comma seperated.
            console.log('Channels Subscribed :',recdData.msg);
            break;
        case workerEvents.event:
            // Data Event received from dataBridges Event listner.
            // Pubished events with data received by dataBridges on the Subscribed channel by this browser connect.
            console.log('Event Received :', recdData.eventname,'Payload', recdData.payload,'MetaData :',JSON.stringify(recdData.metadata));
            break;
        default:
            break;
    }
};

Subscribing to Channel

To subscribe to a channel and listen to an event send a message to dbWebWorker with below parameters. Replace Channel_Name and Event_Name with your Channel Name and Event Name 

dbWebWorker.postMessage({
    cmd: workerEvents.subscribe,
    data: {
        channel: 'Channel_Name',
        event: 'Event_Name'
    }
})

Unsubscribe from channel

To Unsubscribe from a channel send a message to dbWebWorker with below parameters. Replace Channel_Name with your Channel Name.

dbWebWorker.postMessage({
    cmd: workerEvents.unsubscribe,
    data: {
        channel: 'Channel_Name'
    }
})

Subscribed channel list

To get list of all subscribed channels send a message to dbWebWorker with below parameters. 

dbWebWorker.postMessage({
    cmd: workerEvents.channelList
})

Publish events to channel

To publish an event to a channel send a message to dbWebWorker with below parameters. Replace Channel_Name ,Event_Name and Payloadwith your Channel Name , Event Name and Payload 

dbWebWorker.postMessage({
    cmd: workerEvents.publish,
    data: {
        channel: 'Channel_Name',
        event: 'Event_Name',
        payload: 'Payload'
    }
})

Trust Tokens Implementation

While working with Private,Presence or System channel, you need to implement Trust Tokens. There is a function defined in dbridgesDedicatedWorker.js which you can modify to get your own trust token implementation. If you want to use the same functionality, you need to expose /token route in your server and expose the trust token creation functionality.

// Get access token when channel is private,presence  or system.
const getAccessToken = (payloadJson, res) => {
    fetch('/token', {
        method: 'POST',
        headers: {
            Accept: 'application.json',
            'Content-Type': 'application/json'
        },
        body: JSON.stringify(payloadJson)
    }).then(response => {
        if (!response.ok) {
            throw new Error('Network response was not OK');
        }
        return response.json();
    }).then(data => {
        res.end(data);
    }).catch(err => {
        postMessage({
            cmd: workerEvents.dbLog,
            msg: 'dataBridges getAccessToken exception..',
            err: err.source + ',' + err.code + ',' + err.message
        });
        res.end({
            statuscode: 1,
            error_message: error.message,
            accesskey: ''
        });
    });
}