What is an API?

What is an API?

Technically, API stands for Application Programming Interface. At some point or another, most large companies have built APIs for their customers, or for internal use.

But how do you explain API in plain English? And is there a broader meaning than the one used in development and business? First, let’s pull back and look at how the web itself works.

WWW and remote servers

When I think about the Web, I imagine a large network of connected servers.

Every page on the internet is stored somewhere on a remote server. A remote server is not so mystical after all — it’s just a part of a remotely located computer that is optimized to process requests.

To put things in perspective, you can spin up a server on your laptop capable of serving an entire website to the Web (in fact, a local server is what engineers use to develop websites before releasing them to the public).

When you type www.facebook.com into your browser, a request goes out to Facebook’s remote server. Once your browser receives the response, it interprets the code and displays the page.

To the browser, also known as the client, Facebook’s server is an API. This means that every time you visit a page on the Web, you interact with some remote server’s API.

An API isn’t the same as the remote server — rather it is the part of the server that receives requests and sends responses.


APIs as a way to serve your customers

You’ve probably heard of companies packaging APIs as products. For example, Weather Underground sells access to its weather data API.

Example scenario: Your small business’s website has a form used to sign clients up for appointments. You want to give your clients the ability to automatically create a Google calendar event with the details for that appointment.

API use: The idea is to have your website’s server talk directly to Google’s server with a request to create an event with the given details. Your server would then receive Google’s response, process it, and send back relevant information to the browser, such as a confirmation message to the user.

Alternatively, your browser can often send an API request directly to Google’s server bypassing your server.

How is this Google Calendar’s API different from the API of any other remote server out there?

In technical terms, the difference is the format of the request and the response.

To render the whole web page, your browser expects a response in HTML, which contains presentational code, while Google Calendar’s API call would just return the data — likely in a format like JSON.

If your website’s server is making the API request, then your website’s server is the client (similar to your browser being the client when you use it to navigate to a website).

From your users perspective, APIs allow them to complete the action without leaving your website.

Most modern websites consume at least some third-party APIs.

Many problems already have a third-party solution, be it in the form of a library or service. It’s often just easier and more reliable to use an existing solution.

It’s not uncommon for development teams to break up their application into multiple servers that talk to each other via APIs. The servers that perform helper functions for the main application server are commonly referred to as microservices.

To summarize, when a company offers an API to their customers, it just means that they’ve built a set of dedicated URLs that return pure data responses — meaning the responses won’t contain the kind of presentational overhead that you would expect in a graphical user interface like a website.

Can you make these requests with your browser? Often, yes. Since the actual HTTP transmission happens in text, your browser will always do the best it can to display the response.

For example, you can access GitHub’s API directly with your browser without even needing an access token. Here’s the JSON response you get when you visit a GitHub user’s API route in your browser (https://api.github.com/users/petrgazarov):

{
  "login": "petrgazarov",
  "id": 5581195,
  "avatar_url": "https://avatars.githubusercontent.com/u/5581195?v=3",
  "gravatar_id": "",
  "url": "https://api.github.com/users/petrgazarov",
  "html_url": "https://github.com/petrgazarov",
  "followers_url": "https://api.github.com/users/petrgazarov/followers",
  "following_url": "https://api.github.com/users/petrgazarov/following{/other_user}",
  "gists_url": "https://api.github.com/users/petrgazarov/gists{/gist_id}",
  "starred_url": "https://api.github.com/users/petrgazarov/starred{/owner}{/repo}",
  "subscriptions_url": "https://api.github.com/users/petrgazarov/subscriptions",
  "organizations_url": "https://api.github.com/users/petrgazarov/orgs",
  "repos_url": "https://api.github.com/users/petrgazarov/repos",
  "events_url": "https://api.github.com/users/petrgazarov/events{/privacy}",
  "received_events_url": "https://api.github.com/users/petrgazarov/received_events",
  "type": "User",
  "site_admin": false,
  "name": "Petr Gazarov",
  "company": "PolicyGenius",
  "blog": "http://petrgazarov.com/",
  "location": "NYC",
  "email": "[email protected]",
  "hireable": null,
  "bio": null,
  "public_repos": 23,
  "public_gists": 0,
  "followers": 7,
  "following": 14,
  "created_at": "2013-10-01T00:33:23Z",
  "updated_at": "2016-08-02T05:44:01Z"
}

The browser seems to have done just fine displaying a JSON response. A JSON response like this is ready for use in your code. It‘s easy to extract data from this text. Then you can do whatever you want with the data.

A is for “Application”

To close off, let’s throw in a couple more examples of APIs.

“Application” can refer to many things. Here are some of them in the context of API:

  1. A piece of software with a distinct function.
  2. The whole server, the whole app, or just a small part of an app.

Basically any piece of software that can be distinctively separated from its environment, can be an “A” in API, and will probably also have some sort of API.

Let’s say you’re using a third-party library in your code. Once incorporated into your code, a library becomes part of your overall app. Being a distinct piece of software, the library would likely have an API which allows it to interact with the rest of your code.

Here’s another example: In Object Oriented Design, code is organized into objects. Your application may have hundreds of objects defined that can interact with one another.

Each object has an API — a set of public methods and properties that it uses to interact with other objects in your application.

An object may also have inner logic that is private, meaning that it’s hidden from the outside scope (and not an API).

From what we have covered, I hope you take away the broader meaning of API as well as the more common uses of the term today.

Interesting Resources (stuff that I left out but is still very cool):

A great youtube video on DNS (Domain Name System)

HTTP protocol basics

An Awesome Khan Academy video on Object Oriented Design Principles

Thanks for reading

If you liked this post, share it with all of your programming buddies!

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Further reading

The Web Developer Bootcamp

Angular 8 (formerly Angular 2) - The Complete Guide

The Complete JavaScript Course 2019: Build Real Projects!

Modern React with Redux [2019 Update]

Vue JS 2 - The Complete Guide (incl. Vue Router & Vuex)

Build Responsive Real World Websites with HTML5 and CSS3

Build a REST API with ASP.NET Core 2.2

APIs With Node.js and Express: Automatically Validate API Requests Using an OpenAPI 3 Specification

Build a Rest API with Spring Boot using MySQL and JPA

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JavaScript developers should you be using Web Workers?

JavaScript developers should you be using Web Workers?

Do you think JavaScript developers should be making more use of Web Workers to shift execution off of the main thread?

Originally published by David Gilbertson at https://medium.com

So, Web Workers. Those wonderful little critters that allow us to execute JavaScript off the main thread.

Also known as “no, you’re thinking of Service Workers”.

Photo by Caleb Jones on Unsplash

Before I get into the meat of the article, please sit for a lesson in how computers work:

Understood? Good.

For the red/green colourblind, let me explain. While a CPU is doing one thing, it can’t be doing another thing, which means you can’t sort a big array while a user scrolls the screen.

This is bad, if you have a big array and users with fingers.

Enter, Web Workers. These split open the atomic concept of a ‘CPU’ and allow us to think in terms of threads. We can use one thread to handle user-facing work like touch events and rendering the UI, and different threads to carry out all other work.

Check that out, the main thread is green the whole way through, ready to receive and respond to the gentle caress of a user.

You’re excited (I can tell), if we only have UI code on the main thread and all other code can go in a worker, things are going to be amazing (said the way Oprah would say it).

But cool your jets for just a moment, because websites are mostly about the UI — it’s why we have screens. And a lot of a user’s interactions with your site will be tapping on the screen, waiting for a response, reading, tapping, looking, reading, and so on.

So we can’t just say “here’s some JS that takes 20ms to run, chuck it on a thread”, we must think about where that execution time exists in the user’s world of tap, read, look, read, tap…

I like to boil this down to one specific question:

Is the user waiting anyway?

Imagine we have created some sort of git-repository-hosting website that shows all sorts of things about a repository. We have a cool feature called ‘issues’. A user can even click an ‘issues’ tab in our website to see a list of all issues relating to the repository. Groundbreaking!

When our users click this issues tab, the site is going to fetch the issue data, process it in some way — perhaps sort, or format dates, or work out which icon to show — then render the UI.

Inside the user’s computer, that’ll look exactly like this.

Look at that processing stage, locking up the main thread even though it has nothing to do with the UI! That’s terrible, in theory.

But think about what the human is actually doing at this point. They’re waiting for the common trio of network/process/render; just sittin’ around with less to do than the Bolivian Navy.

Because we care about our users, we show a loading indicator to let them know we’ve received their request and are working on it — putting the human in a ‘waiting’ state. Let’s add that to the diagram.

Now that we have a human in the picture, we can mix in a Web Worker and think about the impact it will have on their life:

Hmmm.

First thing to note is that we’re not doing anything in parallel. We need the data from the network before we process it, and we need to process the data before we can render the UI. The elapsed time doesn’t change.

(BTW, the time involved in moving data to a Web Worker and back is negligible: 1ms per 100 KB is a decent rule of thumb.)

So we can move work off the main thread and have a page that is responsive during that time, but to what end? If our user is sitting there looking at a spinner for 600ms, have we enriched their experience by having a responsive screen for the middle third?

No.

I’ve fudged these diagrams a little bit to make them the gorgeous specimens of graphic design that they are, but they’re not really to scale.

When responding to a user request, you’ll find that the network and DOM-manipulating part of any given task take much, much longer than the pure-JS data processing part.

I saw an article recently making the case that updating a Redux store was a good candidate for Web Workers because it’s not UI work (and non-UI work doesn’t belong on the main thread).

Chucking the data processing over to a worker thread sounds sensible, but the idea struck me as a little, umm, academic.

First, let’s split instances of ‘updating a store’ into two categories:

  1. Updating a store in response to a user interaction, then updating the UI in response to the data change
  2. Not that first one

If the first scenario, a user taps a button on the screen — perhaps to change the sort order of a list. The store updates, and this results in a re-rendering of the DOM (since that’s the point of a store).

Let me just delete one thing from the previous diagram:

In my experience, it is rare that the store-updating step goes beyond a few dozen milliseconds, and is generally followed by ten times that in DOM updating, layout, and paint. If I’ve got a site that’s taking longer than this, I’d be asking questions about why I have so much data in the browser and so much DOM, rather than on which thread I should do my processing.

So the question we’re faced with is the same one from above: the user tapped something on the screen, we’re going to work on that request for hopefully less than a second, why would we want to make the screen responsive during that time?

OK what about the second scenario, where a store update isn’t in response to a user interaction? Performing an auto-save, for example — there’s nothing more annoying than an app becoming unresponsive doing something you didn’t ask it to do.

Actually there’s heaps of things more annoying than that. Teens, for example.

Anyhoo, if you’re doing an auto-save and taking 100ms to process data client-side before sending it off to a server, then you should absolutely use a Web Worker.

In fact, any ‘background’ task that the user hasn’t asked for, or isn’t waiting for, is a good candidate for moving to a Web Worker.

The matter of value

Complexity is expensive, and implementing Web Workers ain’t cheap.

If you’re using a bundler — and you are — you’ll have a lot of reading to do, and probably npm packages to install. If you’ve got a create-react-app app, prepare to eject (and put aside two days twice a year to update 30 different packages when the next version of Babel/Redux/React/ESLint comes out).

Also, if you want to share anything fancier than plain data between a worker and the main thread you’ve got some more reading to do (comlink is your friend).

What I’m getting at is this: if the benefit is real, but minimal, then you’ve gotta ask if there’s something else you could spend a day or two on with a greater benefit to your users.

This thinking is true of everything, of course, but I’ve found that Web Workers have a particularly poor benefit-to-effort ratio.

Hey David, why you hate Web Workers so bad?

Good question.

This is a doweling jig:

I own a doweling jig. I love my doweling jig. If I need to drill a hole into the end of a piece of wood and ensure that it’s perfectly perpendicular to the surface, I use my doweling jig.

But I don’t use it to eat breakfast. For that I use a spoon.

Four years ago I was working on some fancy animations. They looked slick on a fast device, but janky on a slow one. So I wrote fireball-js, which executes a rudimentary performance benchmark on the user’s device and returns a score, allowing me to run my animations only on devices that would render them smoothly.

Where’s the best spot to run some CPU intensive code that the user didn’t request? On a different thread, of course. A Web Worker was the correct tool for the job.

Fast forward to 2019 and you’ll find me writing a routing algorithm for a mapping application. This requires parsing a big fat GeoJSON map into a collection of nodes and edges, to be used when a user asks for directions. The processing isn’t in response to a user request and the user isn’t waiting on it. And so, a Web Worker is the correct tool for the job.

It was only when doing this that it dawned on me: in the intervening quartet of years, I have seen exactly zero other instances where Web Workers would have improved the user experience.

Contrast this with a recent resurgence in Web Worker wonderment, and combine that contrast with the fact that I couldn’t think of anything else to write about, then concatenate that combined contrast with my contrarian character and you’ve got yourself a blog post telling you that maybe Web Workers are a teeny-tiny bit overhyped.

Thanks for reading

If you liked this post, share it with all of your programming buddies!

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Further reading

An Introduction to Web Workers

JavaScript Web Workers: A Beginner’s Guide

Using Web Workers to Real-time Processing

How to use Web Workers in Angular app

Using Web Workers with Angular CLI