asaadsaad / MWA-homework03-nodejs02

MWA Homework 03 - NodeJS 02

MWA Homework - NodeJS Core Modules

Exercise 01

Given a file located at the same folder data.json which contains the following JSON structure:

[{"id": 1, "name": "Asaad Saad"}, {"id": 2, "name": "Mike Saad"}, {"id": 3, "name": "Mada Saad"}]

• Create a class Names, once instantiated, it reads the JSON file synchronously, and assigns its content to an instance property.
• Add a method getNames() to emits an event names_all with all name details .
• Add a method getNameById(id) to emits an event names_single with the details about the given id.
• Add a method removeNameById(id) to emit an event names_deleted with a boolean and remove the details about the given id.
• Add a method persist() to write back the instance property of the names into the data.json file, and emit an event names_saved with a boolean to confirm that the file is written successfully.

Test your code:

• create an instance of Names class
• listen to all emitted events
• call all the methods and print appropriate messages.

Exercise 02

Create an asynchronous Node function checkSystem() that returns a Promise object and checks if the system memory size is at least 8 GB and the processor has at least 4 cores (use os core module).

• When you call the function, the console shows a message Checking your system…
• If the system doesn't have enough memory we should reject with a message: This app needs at least 4 GB of RAM
• If the system doesn't have at least 4 cores, reject with this message: Processor is not supported
• If the system has enough specs, resolve with the following message System is checked successfully.

Note: use async/await when calling the function.

Exercise 03

Create a web server that's going to send a response of big file (bigger than 500MB) to any client that sends a request to your specified server:port.
Solve this question in three different ways and inspect the loading time in the browser, try to send many requests at the same time to observe performance differences, and write down your observations.

• Use readFileSync
• Use readFile
• Use streams API