Name: What is an API Gateway?
Uploaded: 2022-05-11T02:22:29.000Z
Duration: 10 min 19 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

API is an acronym for Application Programming  Interface, which is a software intermediary that  

allows two applications to talk to each other.  So every time you use an app like Instagram,  

you send us a message, or check travel prices  for your next vacation, you're using an API.  

APIs can make or break applications and have  to require additional infrastructure to secure,  

scale, and accelerate. And this is the case now  more than ever as organizations are modernizing  

their large legacy monolithic applications  into smaller individual microservices.  

These microservices are loosely coupled  in order to make your apps more scalable,  

highly available, and resource efficient just  to name a few. However, the outcome of using a  

microservice oriented architecture comes with many  more API calls going between your clients and your  

microservices. So, how do you securely manage this  influx of API traffic for a distributed system?  

Well, with an API Gateway! Hell, I even purchased  this nifty medium t-shirt with an API Gateway.  

And the first lucky viewer who answers my API  Gateway question towards the end of this video  

in the comment section will win their own version  of this t-shirt. So now let's take a deeper look  

into how an API Gateway can both improve the user  and developer experience for an online store. So,  

let's start off with an example here let's  say we have a fictitious eCommerce storefront,  

Indie's Custom Threads, and in this store you can  order customized t-shirts, kind of like my nifty  

API Gateway t-shirt here. So let's walk through  the scenario, right. We'd have our users here and  

then they would make the purchase and look at the  t-shirts on the website through these different  

clients, right. So you have your web application  here, which would be a standard web browser.  

We'd have our mobile client as well, it could be  iOS, it could be Android. And then we also have  

a third party API Integration Service, right.  So this could be if you want to integrate your  

website with like say something like facebook, or  in our case we have a Review API that's integrated  

through a third party. So, say you see someone  makes a comment about the t-shirt and they're like  

"man the t-shirt fit comfortable, but the 50  percent polyester really gave me a bad skin  

rash that would all be possible through this  third-party integrated service. So now that  

we've established our users and our clients, now  let's take a look at the actual product detail UI,  

right. So there's a lot of different  functionality, a lot of different tasks  

that we've broken down into these microservices  here. And this originally would be a monolithic  

application like we previously talked about,  but we've broken it apart and segmented it  

into different services. So, as you can see the  first one here is the Product Info Service, this  

would be stuff like you know, look at the t-shirt,  what kind of color is a t-shirt, is it black, red,  

the size of the t-shirt, large, medium, and  so on. And then we have our Pricing Service,  

we have our Order Service if you want to look at  purchase history. You got the Inventory Service  

and the Review Service and so on. And this is  just a handful of different microservices here  

we could have many more. So that's just a very  quick, rudimentary overview of Direct Client to  

Microservice Communication architecture.  So, let's take a look at what an API...

...Gateway architecture might  look like. Let's get rid of these.

Okay, so API Gateway, the topic of the hour.  So, your API Gateway would reside right here  

in the middle between your clients and your  microservices. And there are numerous benefits  

with implementing an API Gateway solution,  but I'm just going to go over just a couple  

main ones right now. So the first main benefit  is client performance. I'm just going to put  

perf for short. So, in our last example we had  our clients making a bunch of API requests to  

each individual microservice. So, in this  instance with our API Gateway, which would  

essentially be like a reverse proxy, or you could  even consider it like an API traffic controller,  

you would take those requests and then route them  to the appropriate microservice. So, this has  

numerous benefits, right, because now instead of  having all those individual requests go into each  

microservice now you can filter it through  your api gateway and this reduces latency.  

So now your product detail UI page will  run much more efficient, much faster,  

and it's a better client experience because  you don't have as many round trips, right.  

Because in our last example say you had a request  come in, it went to the Product Info Service,  

but you're Pricing microservices needs to speak  with the Product one. So you would have to go  

back to the Client, back to Pricing and so on. So  this reduces those round trips here. And on top of  

just being a better, you know client performance,  it also helps the development team as well because  

they don't have to manage and maintain all  those individual API requests. Now they can  

do this all through the api gateway.  So the next main benefit is security.

So, by having this API Gateway right here,  we essentially have a security barrier  

in front of our front-end clients, right. Our  front-end API endpoints. Because otherwise  

we had everything wide open, right. And you're not  as susceptible to like a DoS, Denial of Service  

attack, or any other malicious attack with this  API Gateway. And you could add other services  

within this API Gateway, like authentication,  authorization to add another layer of security.

And this leads me to my next benefit  which is protocol translation.

So if you recall, we had to have the same internet  friendly protocol going from our clients to the  

microservice in order for it to function and  operate. Here we could say we have https.  

The "s" again is secure credential, but we can  change the protocol here we can just go http  

for each API request that's routed. And by  removing the "s" and that secure credential  

you don't have to authenticate this is SSL  termination. Where the SSL stands for secure  

socket layer. And this is a process where  you decrypt and offload the encrypted SSL  

data within the API Gateway instead of going  to our backend microservices. So by doing this,  

this greatly helps performance of our e-Commerce  storefront as you can see. Although I don't know  

why we don't have any more schmediums. You don't  even have to have, you know, internet friendly,  

you can even have server-side protocols like AMQP.  So you have a larger reach, right. You have more  

usability with your e-commerce storefront  because you could have other protocols.

And the last quick benefit  I want to mention is common

So we're offloading these common functionalities  for every microservice that we had to have in  

order for it to operate, right. So, now  we can take some of that business logic  

and put it in this API Gateway. You can just  have your microservices running a little bit  

more efficiently and smoother because we're just  focusing on their tasks that they really need to  

focus on they don't need all that other business  logic. So you could have stuff like rate limiting,  

you could have 10 requests for every 60 seconds  if you want to put a cap on that to help with  

demand. You could also have stuff like API  monitoring and logging if you want to keep  

it on the API health and how everything's working  operational wise. And there's just so much more  

and that's just a few there's a lot more standard  features typically with an API Gateway solution.  

So, this is great and all, but  what if we get an instance where  

say you get a huge spike in traffic and Indie's  Custom Threads is preparing for Black Friday.  

Oh my god, we're going to get so much traffic  what are we going to do? You got users here,  

you got users here. Well we could install  and implement a BFF architecture. And no,  

I'm not saying best friend forever, although I  will be your best friend if you like this video.  

I'm talking about back-end to front-end. And  essentially what this is, is you're adding  

additional API Gateways. So for this one  for instance this would be our dedicated  

Web API Gateway. So here we could have one for our  mobile devices, right, you could have another API  

Gateway. And this would just be dedicated to your,  you know, native iOS and Android devices. And it  

would take all that API traffic coming for those  devices and route them to the right microservices.  

And this is, you know, you could have  this for the third party integration  

service, as well. And there's other clients as  well you can have here, you could have like IoT  

devices with sensors right. So, this is a great  benefit if you're going to have a huge demand and  

spike with traffic, or say you're just adding a  lot more functionality and features to your your  

e-Commerce storefront. So this would be a great  architecture to consider to expand and scale up.  

So this is just a very quick overview of API  Gateway. I hope you found it helpful. Oh,  

and before I forget, I didn't forget the t-shirt.  If you want to get it my question to you is, what  