Programming Languages and REST APIs

Transcript of the free preview lesson. Remaining lessons unlock with the full course.

Hello, my name is Josh Gardino. And in these lessons I will show you how to build simple APIs, using popular, and common frameworks. Let's begin with an exploration of node.js. Node.js server software, based on the JavaScript language. Let's take a look at the Department of Motor Vehicle's API, in its Open API documentation we have endpoints for drivers, registrations, and vehicles, for a variety of HTTP methods, including example values, sets of allowable values, such as those for vehicle makes, as well as the various status codes, that each endpoint might return. Here I am working in JetBrains WebStorm, which is a popular IDE, or integrated development environment, for JavaScript, and other web technologies. WebStorm is not free software, but JetBrains does offer a 30-day free trial. Here in WebStorm, I have a project called "Express-OpenAPI-Starter." Let's take a look at some of the files within this application. App.js starts the API, and leverages several libraries, imported from the public NPM repository, such as Express Open API, and Swagger UI Express. The code here that starts the application, provides a URL for the open API documentation, and the directory and the application, under which all of the information for the various paths will be stored. Now, let's open the API directory, which has three sub-directories. The first one that we will look at is data. To keep this example simple, I do not have the application reading data from a database, but as JSON objects stored in .js files. For example, drivers.json contains all of the driver information. This would certainly not be the way that a production system should operate, but for our purposes here, it should work just fine. There's also a file for registrations, and for vehicles. Now let's look in the paths directory. There is a V1 subdirectory, and then drivers registrations, and vehicles. So this directory structure directly reflects the API's URL, and path pattern. Index.js files are considered root files for each directory, and will contain all of the code for each supported method. Let's look at API/paths/V1/drivers index.js. This file contains code for each of the supported endpoints, such as get, which, on line seven, simply reads all of the drivers from the drivers.json file, and returns them. The post, put, patch, and delete methods, will change the driver information stored in memory, so that subsequent get requests will reflect these changes, although they are not stored back to the JSON files. This means that each time that the server is started. the data in the .json files is reset. And underneath the code that handles the different HTTP methods, is information about the Open API documentation. This refers back to a file called APIdoc.js. And here is where I designate the title, and the version, that are shown on the Open API documentation webpage, as well as definitions for the different types of objects, such as drivers and vehicles. To create fake values for the examples, I'm using a library called Faker, which simply creates fake names, addresses, and dates. The file shown in the directory structure, that have curly braces around ID, are those that support the methods, with IDs of drivers of vehicles, in the URLs. The index.js files also define the response code information. And all of this ties back directly to the Open API webpage documentation. Node.js by itself, does not possess the capabilities to run a web API, so let's use the most common web library for node.js, which is called Express JS. It's very easy to get up and running with a REST API, using node.js in Express. But of course, a real implementation of a production grade REST API would involve significantly more code. Thanks for watching. Stay tuned for the next lesson, where I will show you how to build a simple API using Python.