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MESG Engine

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MESG is a platform for the creation of efficient and easy-to-maintain applications that connect any and all technologies.

MESG Engine is a communication and connection layer which manages the interaction of all connected services and applications so they can remain lightweight, yet feature packed.

To build an application, follow the Quick Start Guide

If you'd like to build Services and share them with the community, go to the Services section.

To help us build and maintain MESG Engine, refer to the Contribute section below.

Contents

• Quick Start Guide
• Services
• Architecture
• Marketplace
• Roadmap
• Community
• Contribute

Quick Start Guide

This guide will show you step-by-step how to create an application that sends a Discord invitation email when a webhook is called.

1. Installation

Run the following command in a console to install MESG Engine:

bash <(curl -fsSL https://mesg.com/install)

You can also install it manually by following this guide.

2. Run MESG Engine

MESG Engine runs as a daemon. To start it, execute:

mesg-core start

3. Deploy the services

You need to deploy every service your application is using.

In this guide, the application is using 2 services.

Start by deploying the webhook service:

mesg-core service deploy https://github.com/mesg-foundation/service-webhook

Deploy the invite discord service:

mesg-core service deploy https://github.com/mesg-foundation/service-discord-invitation

Once the service is deployed, the console displays its id. This id is a unique way for the application to connect to the right service through MESG Engine. You'll need to use them inside the application.

4. Create the application

Now when the services are up and running, let's create the application.

The application is using NodeJS and NPM.

Let's init the app and install the MESG JS library.

Create and move your terminal to a folder that will contain the application. Then run:

npm init && npm install --save mesg-js

Now, create an index.js file and with the following code:

const mesg = require('mesg-js').application()

const email = '__YOUR_EMAIL_HERE__' // To replace by your email
const sendgridAPIKey = '__SENDGRID_API_KEY__' // To replace by your SendGrid API key. See https://app.sendgrid.com/settings/api_keys

mesg.listenEvent({
  serviceID: 'webhook',
  eventFilter: 'request'
})
  .on('data', async (event) => {
    console.log('webhook event received')
    try {
      const result = await mesg.executeTaskAndWaitResult({
        serviceID: 'discord-invitation',
        taskKey: 'send',
        inputData: JSON.stringify({ email, sendgridAPIKey })
      })
      if (result.outputKey !== 'success') {
        const message = JSON.parse(result.outputData).message
        console.error('an error occurred while sending the invitation: ', message)
        return
      }
      console.log('discord invitation send to:', email)
    } catch (error) {
      console.error('an error occurred while executing the send task:', error.message)
    }
  })
  .on('error', (error) => {
    console.error('an error occurred while listening the request events:', error.message)
  })

console.log('application is running and listening for events')

Don't forget to replace the values __YOUR_EMAIL_HERE__ and __SENDGRID_API_KEY__.

5. Start the services

Start the webhook service:

mesg-core service start webhook

Start discord invitation service:

mesg-core service start discord-invitation

6. Start the application

Start your application like any node application:

node index.js

7. Test the application

Now let's give this super simple application a try.

Trigger the webhook with the following command:

curl -XPOST http://localhost:3000/webhook

🎉 You should have received an email in your inbox with your invitation to our Discord. Come join our community.

Services

Services are build and shared by the community. They are small and reusable pieces of code that, when grouped together, allow developers to build incredible applications with ease.

You can develop a service for absolutely anything you want, as long as it can run inside Docker. Check the documentation to create your own services.

Services implement two types of communication: executing tasks and submitting events.

Executing Tasks

Tasks have multiple input parameters and multiple outputs with varying data. A task is like a function with inputs and outputs.

Let's take an example of a task that sends an email:

The task accepts as inputs: receiver, subject and body.

The task could return 2 different outputs.

The first possible output is success with an empty object {} as data, meaning that the email has been sent with success

The second possible output is error with for eg, { "reason": "email invalid" } as data.

This way, the application can easily check the type of output and react appropriately.

Check out the documentation for more information on how to create tasks.

Submitting Events

Services can also submit events to MESG Engine. They allow two-way communication with MESG Engine and Applications.

Let's say the service is an HTTP web server. An event could be submitted when the web server receives a request with the request's payload as the event's data. The service could also submit a specific event for every route of your HTTP API.

For more info on how to create your events, visit the Emit an Event page.

Architecture

Marketplace

We have a common place to post all community-developed Services and Applications. Check out the curated list of Awesome Services and Applications to participate.

Alternatively, you can also check out the https://github.com/mesg-foundation/awesome#readme.

Community

You can find us and other MESG users on the forum. Feel free to check existing posts and help other users of MESG.

Also, be sure to check out the blog to stay up-to-date with our articles.

Contribute

Contributions are more than welcome. For more details on how to contribute, please check out the contribution guide.

If you have any questions, please reach out to us directly on Discord.