00:01Hello and welcome to the second video of the NN beginner course

00:03Today, we will be talking about APIs and webhooks, two very important notions that you need to understand before building your first end-to-end workflows

00:13In this video, we will be covering what an API is, as well as a definition and an explanation of its main components

00:24And we will be talking about webhooks, sometimes called reverse APIs

00:31So, first of all, what is an API? I'd like to start by explaining an analogy that is going to be very useful for understanding not only what an API is, but also the different parts and names associated with them

00:45So, imagine you're sitting at a restaurant, and you go and you sit at a table

00:51How do you get food? Well, you ask a waiter, and the waiter is going to to to take your order and bring it to the kitchen

01:01Once the kitchen is done preparing your food, the waiter will bring back your food to the table

01:09This is very, very similar to how an API works

01:13Um, we're going to be using, uh, this analogy to explain the different parts of an API

01:21Um, so keep this in mind while we go through this video

01:27A technical definition of an API

01:30So, an API is an application programming interface

01:35It exposes a service, and developers write programs to consume it

01:42So, if we go back and we think of the actions or the apps in the past video, we might take the example of Google Sheets

01:51So, Google Sheets has an API, and in the API, we have different services

01:55So, one of these services might be, get all of the data in a specific sheet, and so the Google Sheets API exposes the service that allows you to read data in the sheet

02:09Developers write programs to consume it

02:12So, using n8n, we're going to be able to consume the Google Sheets API using the different services, for example, updating rows or getting data in a sheet

02:27Using this metaphor, we can see that the waiter is what's going to be called the interface, and the application is going to be the kitchen

02:36So, in this case, the application might be Google Sheets, and then we're going to be using the interface to interact with the application

02:52Why do we need this interface to interact with the application? Well, it allows us to abstract the complexity

03:00Imagine if every time you went to a restaurant, instead of just sitting down and ordering food, you had to go to the kitchen and explain your order, wait for it to be done, and then take your food back to your table

03:13This would be much more complicated than just asking the waiter for your food

03:18The same thing goes for applications

03:21If every time you wanted to read data in a Google sheet, you had to go to Google servers, find your specific sheet, and then read the data from it, that would be much more complicated than just using the API, which gives you a very abstract but easy way to access the data from the application

03:46So, how does an API work? It uses what's called documentation

03:50So, documentation explains how the application programming interface, or API, works

04:00And using the restaurant, um, analogy, it in In this case, it would be the menu

04:07So, a little bit of terminology, we send a request through the interface to the application, and the application uses the interface to send a response

04:13We also have the client-server notions

04:20In this case, you would be the client, and the application and the interface would be the server

04:27So, keep these in mind when you see these terms

04:34When using APIs, we have, as mentioned earlier, requests and responses

04:41So, we're going to break down the different components of a request and the different components of a response, starting with a request

04:47There are four main components to an HTTP request, and in these videos, we're only going to be talking about HTTP requests

04:55There are different frameworks to make API requests

05:00such as GraphQL, but most of the APIs that you're going to use are going to use the HTTP framework

05:08Everything that we're going to talk about today is mirrored in the HTTP request node

05:13The HTTP request node allows you to make HTTP requests in n8n and receive the responses

05:21This is going to be very useful when building automations that need to use specific APIs

05:30There are four components to an HTTP request: there is the URL, the method, the header, and the body

05:36Let's look at each one of them

05:38The URL is the unique location for a resource on the web

05:41This can be a page, an image, a PDF, or some data

05:47Here we have an example of a URL

05:51You can see a scheme, a host, a port, a path, and some query parameters

05:57The scheme, the host, and the path are going to be mandatory, and the port and query parameters are going to be optional

06:06Something that is important to note, query parameters are always preceded by a question mark

06:10Then we have the method

06:14The method describes the action that we want to perform at the given URL

06:18There are two main methods that we're going to be using for HTTP requests, there is the GET and the POST method

06:28GET, most of the time, allows us to receive information

06:34So if you're reading data in a Google Sheet, you're using the GET method

06:40And POST is going to allow us to send information

06:43So if we want to send information from a form submission, we're going to be using the POST HTTP method

06:52The other methods are a little bit more rare, we have for example, DELETE, PUT, and patch that are less common but can be used

07:03What's very interesting with the method is there are all the time verbs, which means that they describe very clearly what we're trying to do

07:11So when wondering which method you need to use, think of which verb would be most appropriate to the action you're trying to accomplish

07:17Then we have the header

07:24The header gives us a little bit more detail or context for a given request

07:30So, for example, common information that you will find in a header is going to be your location, or your language preference, or your device type

07:38Every time you open a page on the internet, you're making an API request to a server, and the server is responding with the web page

07:51So if you are browsing the internet, on your computer or on your laptop, you're going to have different information or context in the header of your request

08:06An example of a header would be "Accept: application/json," which tells the server that it would like the response of the HTTP request in the JSON format

08:13Then we have the body

08:19The body is optional and only exists for POST requests

08:26It contains the information we would like to send to the server or application

08:32So, if we take the example of form submission, then the body might contain first name, Maxim, last name, Poon, and then the associated email

08:44So, this is the information that we are sending to the server

08:49Finally, we have credentials

08:55So, the credential wasn't listed as a main part of the HTTP request because it isn't, um, a part on its own

09:00There are many different ways to use credentials

09:03A credential is how we let the application know that we are allowed to make a given request

09:13As you can imagine, if anyone could read your Google Sheets or update your Google Sheets or send messages on Slack, that would be very dangerous

09:21So, we include credentials in our HTTP requests to indicate to the server, I am authorized to make this request

09:34Most APIs require authentication through credentials

09:37However, there are some APIs that do not require authentication

09:43The two most common ways to authenticate to a service are going to be through query parameters, question mark API key equals followed by the API key, or header authentication, for example

09:59authorization: Bearer followed by the API key

10:03Another very common way to authenticate to a service is through OAuth

10:05Every time you click "Sign in with Google" and the little window opens and you sign in with your Google account, this is an OAuth authentication method

10:20Now, we've seen everything that we need to send a request

10:23Now we're going to look at how the application is going to answer with a response

10:30There are three main components to an HTTP response: the status code, the header, and the body

10:39The status code is a three-digit number which will give you information on whether the request was successful or unsuccessful

10:49The most common status codes are going to be 200, which means okay

10:55This is the standard successful response

10:58it means your API request was executed well and the application is telling you, "Congrats, you did a good request." 401, which means unauthorized, this is usually an authentication problem

11:14This is the application telling you, "The request that you sent me does not contain the authentication information necessary to make this request." This means you need to go back and check your credentials and how you sent them, or the access that your credentials have

11:27Another one is 404

11:40You might not remember this from the web, "Not found." Usually, this is a problem with the URL and means that the page or data you are looking for is not on the URL that you indicated

11:53Finally, we have 500, which is "Internal server error," which indicates that the server had an error

11:58Um, this means it was not your fault, but the server's fault

12:02In general, the very easy way to remember and understand these codes

12:08If the status code starts with a two, congrats, it was a successful HTTP request

12:14If it starts with a four, you made some kind of error and you need to modify your request

12:20500 means it was the server's error

12:23Most of the time, it just means try again later

12:31Then, the same way we included a header in the request, the application is going to send a header in the response, giving more context or detail

12:41So, some common response headers are going to be: how long is the content, so how much content is in the response, what type of content is it, or when does this content expire? Um, so when, how long am I going to have access? access to it

13:01For finally, sometimes we're going to have a body

13:04The body is the actual data being returned

13:06It can be in many different formats

13:09It can be HTML if we're browsing the web, it can be JSON, or it can be any other forms of data, for example, binary data

13:21Then let's quickly talk about webhooks

13:24Webhooks are reverse APIs

13:28So imagine you're at home waiting for some friends

13:31You can either go and check the door every few minutes to see if they've arrived, or you can wait for the doorbell to ring

13:39The doorbell in this analogy is a webhook

13:43It is what indicates that something that you are waiting for happened

13:48So let's say you're using Stripe

13:51Uh, Stripe is a developer platform to manage payments, and you need to know every time a new payment is Made in your Stripe account

13:59Well, there are two options

14:02Either we can do what is called polling, so every few minutes, for example, we can make a new request to Stripe, a new API request, saying, "Is there a new payment?" If yes, do some actions

14:16If no, wait and every few minutes, keep asking and keep polling the Stripe application to see if we have a new payment

14:26Or we can set up a webhook, and every time that a new payment is made in Stripe, a webhook is going to be sent to us synchronously, um, giving us the information on the payment

14:39So every time we're waiting for something to happen or we're waiting for information from a specific application or service, sometimes these applications are going to allow us to create webhooks, what we need to set up a A webhook is a URL, which is the location we are sending the information to

15:01And then we can use a tool like n8n and the webhook node to receive and manage and deal with this information, triggering a workflow

15:13That was it for the second video of this beginner course on APIs and webhooks

15:19In the next video, we will be covering end-to-end nodes and everything you need to know to start building your first workflows

15:25See you in the next video.