What is a REST API?
What are the benefits
- and how are they fundamental to your cloud application development?
I'm Nathan Heckman from IBM Cloud,
and I'm going to answer that for you today,
but before i do please hit that subscribe button.
Let's jump in with an example.
Let's say that you work for an ice cream shop
and you're trying to build a web application
to show the flavors of ice cream that are in stock that day
and allow the workers to actually make updates to those flavors.
How do you do this?
Well, with a REST API.
You have your web app or web page communicate with a cloud-based server
via a REST API. Great!
So, let's jump into what exactly a REST API is.
Starting out with: what does "REST" stand for?
So, REST stands for Representational State Transfer.
So it's "REST".
Those words might not mean a whole lot to you
but, basically, it's a standardized software architecture style,
a specific type of API that's industry known and used.
So, the first thing that you should really know about REST APIs
is they're all about communication.
So, client with server and vice versa - that's how they talk,
and also you may have heard the term "restful".
So, "restful web service", right, that's a service that uses REST APIs to communicate.
So, what are some of the benefits of REST APIs?
First of all, they're a simple and standardized approach to communication.
You don't have to worry about how to format your data,
or how to format your request each time -
it's all standardized and industry used.
Second of all, REST APIs are scalable and stateless.
So, as your service grows in complexity you can easily make modifications
and just the fact that they're stateless means you don't have to worry about
what data is in which state and keep track of that across client and server.
It's truly stateless.
Great, and then finally
they have high performance
in large part due to the fact that they support caching.
So, that's all all good stuff - as your service gets more complex
the performance stays very high.
Great! So, let's go back to our example.
So, for the ice cream shop, what would the REST API look like?
So, you have an endpoint which might look something like this:
"icecream.com/api/flavors"
Right? So, let's break that apart a bit.
So, "api" this just signifies that this is the API portion of the endpoint.
Right? So, pretty straightforward there.
"Flavors" is actually what's known as a "resource".
So, this signifies that we're working with the flavors resource in this this REST API.
Great!
So, in our example,
the main building blocks, or parts, of the REST API are:
the "request", that is sent from the client to the server,
and the "response", that is received back from the the server.
So, let's let's break those apart a little bit.
Over here, let's put a big old box for request,
and what are the type of things that you might want to do with a REST API?
What actions or verbs would you want to make when you're working with one?
You may have heard of "CRUD" - what does CRUD stand for?
So, CRUD is "Create, Read, Update, and Delete".
These are some of the main things that you might want to do
when you're communicating with your client and server.
On a REST API, the equivalent of those are are actually HTTP "methods"
or "operations".
So, what's the equivalent of "create" in an HTTP method?
Well, it's "post".
And how about "read"?
So, read is actually called "get".
Update or replace is "put",
... and delete? Guess what it is: "delete".
Not too creative there.
So, how about a request itself?
What are some of the pieces of it?
So, first of all, you might have an operation,
that's kind of what we just talked about here with the HTTP methods,
you might have an endpoint,
which is what we just talked about over here -
this is your REST API endpoint,
and then you might also have parameters or body,
which is some data that you might send in the request,
and we'll see some examples in a moment,
and finally are the headers.
So, this is a special part of an REST API request
which might have things like an API key or some authentication data.
Great - and then, in return, from the server, you'll receive a response, right?
So, we'll put a nice box here for response
and this is typically in the form of JSON data.
Great, so let's jump into our example,
and let's look at a few different scenarios that might happen with your ice cream shop, right?
So, first of all,
let's say that you want to display what's currently in stock, right?
So, we want to get the flavors that are in stock.
So, what does our rest API request look like?
Well, you have a "get" as the operation,
because you're actually wanting to get those flavors,
and then the end point is "/api/flavors",
and, in response, you'll get an array of those flavor resources, right?
So, we see strawberries in stock, as well as mint chocolate ... yummy!
but then, uh oh, mint chocolate is so popular
that it actually runs out for the day,
and the store is scrambling and they want to replace that flavor with another one.
They choose chocolate. Which is a great choice!
So, let's say they want to update the flavors, right?
So, you want to update or replace that mint chocolate with just chocolate.
So, what does our request look like?
It's a "put" operation, so that updates or replaces.
The end point is "/api/flavors/1" to indicate the the ID of "1" you want to replace
and then parameter body you actually specify the flavor of chocolate,
which is going to be the new flavor that's replaced.
And, in response, we see indeed acknowledging that the ID of "1"
is replaced with a flavor of chocolate. Great!
Good news: the store just received a shipment of a brand new experimental flavor
called "restful raspberry",
and you want to actually load this new ice cream up into your website, right?
So, we want to create a new flavor.
How do we do that with the REST API?
Well, in our operation it's a "post" operation,
so that actually will create a new flavor,
the endpoint is once again "/api/flavors",
and we included in the body the flavor that we want to create,
which is "restful raspberry",
and in response we see ... yep, this new ID of "2" was created,
the flavor is restful raspberry.
Great! So, hopefully this clarifies what exactly is a REST API?
What are some of the benefits? What's a real world example look like?
... and how are REST APIs fundamental to your cloud application development?
Thank you.
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