Alien City Using AppSail

Introduction

This tutorial will help you build a Node.js Express web application called Alien City, and host it using Catalyst’s serverless offering, AppSail. AppSail is a highly scalable PaaS component that allows you to code your application in any programming framework of your choice, independent of any Catalyst-specific coding structures, and host it on Catalyst with ease.

Alien City is a fun application that allows you to search for and report alien encounters in a city.

The web application will appear as follows:

The Alien City application utilizes components from the following Catalyst Services:

1. Catalyst Serverless:

   • AppSail: To host the independent Node.js Express application. We will be building the front-end of the app as well as the backend logic, and bundling them together to deploy on AppSail.

2. Catalyst Cloud Scale:

   • Data Store: To store the database of the cities where alien encounters have been reported.
   • ZCQL: To fetch data from the Data Store through querying.

You will use the Catalyst web console and the Catalyst Command Line Interface (CLI) to build this application.

You will be given the code for the files to be included in the application in this tutorial. You will just need to copy the code and paste it into the appropriate files as directed.

Application Architecture

The Alien City application’s functioning can be described as follows:

• Reporting an alien encounter
  A user enters the name of a city where they experienced an alien encounter. If the city had already been reported previously, the app displays a message notifying the user of it. If the city has never been reported, the data will be added to a table in the Data Store identifying the city.

• Checking for an alien encounter
  A user checks for a record of an alien encounter in a particular city by providing its name. If a record of that city exists in the Data Store, the app will display a positive response. Otherwise, it will display a negative response.