koios-faucet

Intro

Koios-faucet is a back-end service for the Koios platform. It is primarily used as a middleware for handling certain functions that should be done off-chain.

Architecture

The architecture currently follows a Service-Based Software Architecture. Modules can talk down but not up. For example, a service should not be able to call a controller and a controller should not be able to call a router. But within a Service-Based Architecture we do allow services to call each other, only if needed. This is because each service has its own domain. Think of Service-Based as Domain Driven Design.

Folder structure

• Routes, the different API endpoints the client is able to call. The requests get routed to their corresponding controler.
• Controllers, this is where the API requests get handled through the different endpoints.
• Services, controllers call their corresponding service, in the service business logic gets handled.
• Repositores, when a service needs to make a call to a database it will be handled within its corresponding repository component (not created yet not needed)
• Interfaces, folder for all the interfaces that are being used.
• Json, folder for static .json data.

Adding a new endpoint

For adding a new endpoint a few things need to be created, let's call the new endpoint: NFT. We want to get NFTs from a certain address.

Creating the routes

In the routes folder create a new: NFTRouter.ts

import express from "express";

//Don't worry about the controller yet
import * as NFTController from "../controllers/NFTController";
export const NFTRouter = express.Router();

NFTRouter.route("/:address").get(NFTController.get);

Creating the Controller

In the controller folder create a new: NFTController.ts

import { NextFunction, Request, Response } from "express";

//Don't worry about the service in this step yet
import { fetchNFTs } from "../services/NFTService";

export const get = async (req: Request, res: Response, next: NextFunction) => {
  const NFTs = await fetchNFTs(req.params.address);
  if (NFTs) {
    return res.send(NFTs);
  }
};

Creating the Service

In the services folder create a new: NFTService.ts

export const fetchNFTs = async (address: string) => {
const fetchedNFTs = //fetch NFTs implementation;
 return NFTs
};

Using this pattern may cost some more time in the beginning, but it makes everything much more expandable and manageable.