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Bachelor's Degree Final Work

Disclaimer ⚠️

10/2019 🚧 - I wrote this code in 2016, before ECMAScript 2016 and even ES6 wasn't fully implanted. This, and the fact that I was a student with little experience outside the academic world... resulted in low quality code. I am leaving the repository for documental reasons, but the code should not be considered in high regard (or any regard 😿). I do not intend to update the code.

These are some of the key modifications, among the thousands it needs, that I think the code needs to be up to date:

  • Transition from js entities to js classes.
  • Proper documentation.
  • Update to new ES standards (e.g: use of let, const etc.)
  • Update some of the callbacks to promises.

What is this?

A repository where I will upload the code of my BDFW (Bachelor's Degree Final Work). My BDFW is about updating distributed services based on passive model replication, also known as the primary-backup approach.

As part of my work I am developing a demo to show my updating algorithm in action. It's a simple one with basic client/server interaction. Some premises are supossed to facilitate the development of the distributed system. The reason is that the goal of my BDFW is not to develop a completely real primary-backup service. My goal is to develop an effective way to update those systems without interrupting the service.

The service emulates a simple distributed shop which accepts client's requests.

Files

  • auxfunctions.js: Auxiliar functions library.

  • domainName.js: Acts like a a DNS for the service. Any client should request domainName.js for the primary's address. It is assumed the DNs is replicated in case of failure.

  • updateManager.js: It has the control of how many copies are launched and it handles failures if the occur. (It does what a distributed system shoul do in a centralized way, as mentioned above developing a complete distributed system is not the aim of this project).

  • client.js: Simple client to interact with servers. It makes a random request (buy, return, get getAll).

  • administrator.js: Special client to to add/remove items from the shop.

  • server.js: The real thing. The back-ups. The primary answer client's requests and propagates the changes to all the back-ups. This version has a little error created on purpose. It is just a functionality error.

  • server2.js: A new version server.js but solves the error. It solves the previous error.

  • server3.js: A newer version of server.js, it solves the previously mentioned error and updates its own state proving backwards compatibility.

  • failover.js: Simple piece of code to start the simulation of primary's failover.

  • initiateUpdate.js: Special client to start the update process.

  • launcher.sh: Script to launch the demo.

  • primaryFails.sh: Script to test the updating algorithm under certain conditons.