Fibonacci REST API

The Fibonacci REST API has only one single feature:

• Given an index n, the API will reply with the value of the n position of the Fibonacci series. Example: if n=3 response should be 2, if n=6 response should be 8.

Objective

This repository will be used to versioning the code of the solution but also as a journal or notebook about the process followed to implement the solution.

Try it locally

Pre-reqs:

• node.js

Steps:

1. Clone this repo

   git clone https://github.com/rastangineer/fibonacci-rest-api.git
   cd fibonacci-rest-api

2. Install packages

   npm install

3. start server locally

   node app.js

4. Send requests with Postman or a similar

   

Initial challenges

1. I don't consider myself a REST API developer, or even a developer.

   • But I have plenty of experience working with middleware, HTTP, SOAP and REST protocols. I used to be a Java developer long time ago.

2. What programming language to use?

   • From previous personal projects I can say I'm more familiar with node.js and I read that express.js is a web framework for node.js that allows you create to REST APIs quickly. So the winner is node.js + express.js

3. I'm familiar with REST API services, SOAP/HTML Web Services and similar technologies, but should I start with design or just start googling and try?

   • Definitively YES, that would help to identify the modules/functions needed.

     

   sequenceDiagram
   participant C as :Client
   participant S as :Server
   
   C ->>+ S: GET /api/fibonacci_number (index)
   S ->>+ S: Generate Fibonacci series
   S -->>+ C: Response with fibonacci[index] value
   

   Loading

4. How do I start with something basic?

   • I like to start with the very basics, and then gradually add funcionality in a iterative and incremental way. Since I'm new developing REST APIs I would start with the most basic thing, the famous Hello World, for example an API that just replies with the text Hello World.
   • Next step would be passing something like the username using parameters and reply with something like Hello World username.
   • Now that we are able to pass and read parameters, we can start thinking about how to generate the Fibonacci series, from what I remember from college this is a very good use case for recursive programming.

5. Thought process?

6. Technical decisions?

   • What is the maximun index n allowed.
     • In theory, it shouldn't have a limit. So it's important to be able to handle big values for n.
   • Harcoded Fibonacci series? Or Fibonacci series generated on each request.

7. Optimizations

   • After initial tests with recursive programming I have found that this a very time consuming method, the bigger the parameter the longer it takes to generate the fibonacci series.
   • Alternative 1:
     • Using the golden ratio phi ^ n / sqrt(5) where phi = (1+ sqrt(5)) / 2 we might get better performance, but values might not be accurate after n > 77. Reference
   • Alternative 2:
     • Using a while loop, by using the formula f(n) = f(n-1) + f(n-2) where f(0) = 0 and f(1) = 1
   • Alternative 3:
     • How about hard-coding the fibonacci series and store it in an array, then just reply with array[n], no calculations. Just saying I haven't really thought about it.