Code Gen Workshop

About

Bee Travels is a travel booking application that is composed of several mircoservices. These microservices include:

Hotel Microservice
Car Rental Microservice
Flight Microservice
Currency Exchange Microservice
UI Front End
UI Back End

Each mircoservice can be run independently, or together to form the full service. Bee Travels can be used to search and book hotels, flights and car rentals for various destinations across the world.

Overview

In this workshop we will be using the Node.js code generation service template to seemlesly create microservices in Node.js. We will be creating our own budgeting microservice using the Bee Travels Node hotel and car rental microservices to build a microservice that gives a list of hotel and car rental combinations for a location that fit into a given maximum budget.

Let's get started!

Prerequisites

Install Docker
Install Yarn
Install Node Version 12.0.0 : nvm install v12.0.0

Getting Started with Code Generation Node Template

Step 1

Make a directory with any name and cd into it. Once you are in the directory run : npx bee-bootstrap node

Name the following :

Service name (destination-basic): budget
Service route (destinations): budget
Service port (9000):9000 

Step 2

At this point you should see a folder in your directory with the service name you just created. In our case this folder is called budget. If you cd into that folder you will see a src folder, a dockerfile , a package.json, and a README.md file :

cd into budget and run yarn

Make sure you are using Node version 12.0.0 if not you can install with nvm install v12.0.0

You should see :

yarn install v1.22.5
info No lockfile found.
[1/4] 🔍  Resolving packages...
[2/4] 🚚  Fetching packages...
[3/4] 🔗  Linking dependencies...
[4/4] 🔨  Building fresh packages...
success Saved lockfile.
✨  Done in 9.64s.

Step 3

Run yarn start and you should see :

yarn run v1.22.5
$ nodemon -r esm ./src/bin/www.js
[nodemon] 2.0.6
[nodemon] to restart at any time, enter `rs`
[nodemon] watching path(s): *.*
[nodemon] watching extensions: js,mjs,json
[nodemon] starting `node -r esm ./src/bin/www.js`

✨ You've saved 6 lines of extra YAML (▼ 24.0%)

Listening on port 9000

Now go to http://localhost:9000/api-docs/

You should see the service up and running

Congrats you have the Node Service template up and running! Lets get started with building the budget microservice.

Building a Budget Microservice

Step 1

Our budget service api will be taking in data such as :

city
country
date from (arriving date)
date to (departing date)
max cost

We need to create a GET request api endpoint that requires this information

In budget > src > routes you will see a file called budget.js This is the file where we will be creating our GET request api.

The api endpoint of this file will be /api/v1/budget/{country}/{city}

You can replace all the code in this file with this budget.js code

The GET request is the main aspect of this code that is created to set up the data that will be required by this API

/**
 * GET /api/v1/budget/{country}/{city}
 * @tag Budget
 * @summary Get list of hotels and car rentals that fit a budget
 * @description Gets data for hotel and cars associated with a specific city and budget.
 * @pathParam {string} country - Country of the hotel using slug casing.
 * @pathParam {string} city - City of the hotel using slug casing.
 * @queryParam {string} dateFrom - Date From
 * @queryParam {string} dateTo - Date To
 * @queryParam {number} maxcost - Max Cost.
 * @response 200 - OK
 * @response 500 - Internal Server Error
 */
router.get("/:country/:city", async (req, res, next) => {
  // const context = new Jaeger("city", req, res);
  const { country, city } = req.params;
  
  const {
    maxcost,
    dateFrom,
    dateTo,
  } = req.query;
  req.log.info(`getting budget data for -> /${country}/${city}`);
 
  try {
    const data = await breaker.fire(
      country,
      city,
      {
        maxCost: parseInt(maxcost, 10) || undefined,
        dateFrom: dateFrom || undefined,
        dateTo: dateTo|| undefined,
      },
      context
    );
    res.json(data);
  } catch (e) {
    console.log(e)
    next(e);
  }
});

Step 2

The budget service is dependent on the hotel microservice and the car rental microservice. We will be creating a budget service that gives us both hotel and car data based on our max budget.

The first thing we need to do before we build our microservice is get both the hotel microservice and car microservice up and running

Run Hotel Service

Make sure you have docker installed and in a seperate terminal window run the following commands :

docker pull beetravels/hotel-v1:node-540d5182fe943a3ad87c559dd7fcce025cec9833
docker run -p 9101:9101 beetravels/hotel-v1:node-540d5182fe943a3ad87c559dd7fcce025cec9833

You should see :

✨ You've saved 53 lines of extra YAML (▼ 54.6%)
Listening on port 9101

If you go to http://localhost:9101/api-docs/ in your browser you should see your hotel service up and running.

Run Car Service

Run the following commands in another terminal window to run the car service :

docker pull beetravels/carrental-v1:node-540d5182fe943a3ad87c559dd7fcce025cec9833
docker run -p 9102:9102 beetravels/carrental-v1:node-540d5182fe943a3ad87c559dd7fcce025cec9833

You should see :

✨ You've saved 57 lines of extra YAML (▼ 54.8%)

Listening on port 9102

If you go to http://localhost:9102/api-docs/ in your browser you should see your car service up and running.

Now that you have both these services up and running you can call both hotel and car apis in your budget microservice

Note : If you would like to kill your docker containers run docker ps to locate the running containers and then run docker kill <CONTAINER ID> to kill any running containers

Step 3

With both hotel and car microservices up and running we can now create a hotel.js file and a car.js file that individually calls on these apis to get both hotel and car data

In budget > src > services create a hotel.js file and then create a car.js file

hotel.js file :

Add this code to the hotel.js file to call the hotel microservice

import axios from "axios";

const HOTEL_URL = process.env.HOTEL_URL || "http://localhost:9101";

export async function getHotelData(country,city,dateFrom,dateTo) {
  const data = {
    dateFrom: dateFrom,
    dateTo: dateTo
  };
  const res = await axios.get(HOTEL_URL + `/api/v1/hotels/${country}/${city}`, {params:data});
  return res.data;
}

export async function hotelReadinessCheck() {
  const isReady = await axios.get(HOTEL_URL + "/ready");
  return isReady;
}

Notice that you are calling the hotel api with the country and city end point. You can use the hotel.js code as a reference

car.js file :

Add this code to the car.js file to call the car microservice :

import axios from "axios";

const CAR_URL = process.env.CAR_URL || "http://localhost:9102";

export async function getCarData(country,city,dateFrom,dateTo) {
  const data = {
    dateFrom: dateFrom,
    dateTo: dateTo
  };
  const res = await axios.get(CAR_URL + `/api/v1/cars/${country}/${city}`, {params:data});
  return res.data;
}

export async function carReadinessCheck() {
  const isReady = await axios.get(CAR_URL + "/ready");
  return isReady;
}

You can use the car.js code as a reference

Step 4

Now that we have created both hotel.js and car.js files we are going to be adding some code to the budget > src > services dataHandler.js file

In this file we will be creating a function that does 5 steps

Makes sure date range is valid
Calls the hotel service api end point
Calls the car service api end point
Finds car and hotel based on max price , date range and location
Return a list of hotel and car data combinations based on max price, date range and location

You can replace all the code in the dataHandler.js file with this dataHandler.js code

import IllegalDateError from "../errors/IllegalDateError";

import { getHotelData, hotelReadinessCheck } from "./hotel";
import { getCarData, carReadinessCheck } from "./car";

export async function getData(country, city, filters, context) {
// step 1: Makes sure date range is valid
  const {maxCost} = filters;

  if (parseDate(filters.dateTo) - parseDate(filters.dateFrom) < 0) {
    throw new IllegalDateError("from date can not be greater than to date");
  }

// step 2 : Calls the hotel service api end point 
const hotelData = await getHotelData(
  country,
  city,
  filters.dateFrom,
  filters.dateTo
  );

// step 3 : Calls the car service api end point 
const carData = await getCarData(
  country,
  city,
  filters.dateFrom,
  filters.dateTo
);

// step 4 : Finds car and hotel based on max price , date range and location
let results = [];
let hotelIndex;
let carIndex;
let budgetOutput;


for (hotelIndex = 0; hotelIndex < hotelData.length; hotelIndex ++){
  if(hotelData[hotelIndex].cost <= maxCost){
    
    for(carIndex = 0; carIndex < carData.length; carIndex ++){
      budgetOutput  = hotelData[hotelIndex].cost + carData[carIndex].cost;
      if(budgetOutput <= maxCost){
        results.push({hotel:{id:hotelData[hotelIndex].id,name:hotelData[hotelIndex].name},
        car:{id:carData[carIndex].id,name:carData[carIndex].name},cost:budgetOutput});
      }
    }

  } 
}

// step 5 : Return a list of hotel and car data combinations based on max price, date range and location
 return results
}

function parseDate(date) {
  return Date.parse(date);
}
export async function readinessCheck() {
  return true;
}

Step 5

In the budget > src > errors folder create a file called IllegalDateError.js to flag any errors with incorrect date format.

Add the following code or refer to IllegalDateError.js

class IllegalDateError extends Error {
  constructor(date) {
    super(`Date not legal ${date}`);
    // Ensure the name of this error is the same as the class name
    this.name = this.constructor.name;
    // This clips the constructor invocation from the stack trace.
    // It's not absolutely essential, but it does make the stack trace a little nicer.
    Error.captureStackTrace(this, this.constructor);
  }
}

export default IllegalDateError;

Step 6

Once you have these files set up and you have completed all previous steps you are now ready to run the application

Run yarn start

You should see :

yarn run v1.22.5
$ nodemon -r esm ./src/bin/www.js
[nodemon] 2.0.6
[nodemon] to restart at any time, enter `rs`
[nodemon] watching path(s): *.*
[nodemon] watching extensions: js,mjs,json
[nodemon] starting `node -r esm ./src/bin/www.js`

✨ You've saved 33 lines of extra YAML (▼ 55.9%)

Listening on port 9000

If you go to http://localhost:9000/api-docs/ you should see the /api/v1/budget/{country}/{city} api end point.

Click on the Try it out button to try out the service with the required parameters - for example :

country : united-states
city : new-york
dateFrom : 2020-11-20  (Use this format for a date in the future)
dateTo : 2020-11-30 (Use this format for a date in the future from dateFrom)
maxcost : 1500

Click on the Execute button you should see the following output :

Note : This might take some time to run

Congratulations

Congrats on creating the budget microservice! You can now consider deploying this application.

About#

Overview#

Prerequisites#

Getting Started with Code Generation Node Template#

Step 1#

Step 2#

Step 3#

Building a Budget Microservice#

Step 1#

Step 2#

Step 3#

Step 4#

Step 5#

Step 6#

Congratulations#

About

Overview

Prerequisites

Getting Started with Code Generation Node Template

Step 1

Step 2

Step 3

Building a Budget Microservice

Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

Congratulations