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In this video.

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Let's talk about how many were works.

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So here we go.

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Let's take it that we have this client who is using our application, and the application is about a

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block application.

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So we are going to implement some layers or some security.

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First is you need to log in before you can use our application.

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So now let's say that this is our server.

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Now we have the user here and our server there is express server.

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And before a user can create a post, the person needs to log in so the user make a first request and

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then before the request gets into the server, it needs to go through some paths or some steps.

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And this what you call the middleware steps, because what we want is that you want to check one if

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the user is logging, and two, if the user account is verified, and three, if the user is an admin.

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Before we can allow you to use our server, these are our lists of business logic.

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So let's say that this user has entered his or her login credentials and then before the request or

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this one will get into the server.

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We have implement a middleware to check if this user login credentials are correct.

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So after checking using this middleware for log in, if the user logging credential is wrong, we are

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going to throw an error, meaning that the requests have not even go to the server, but because of

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the middleware we can end the request here and through error to the user that invalid log in credentials.

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But let's say that this user has provided the right login credentials.

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In that way, we need to move to the next middleware.

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So we are going to call what is called next.

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So this means that this particular user has provided the right login credentials, meaning the user

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has passed the first middle word.

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So in that case, we are going to call next move to the next media world.

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And moving to the next middleware, we can throw an error or we can proceed to the next middleware.

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So let's say that this user has provided the right logging credentials.

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Let's see the flow next is we have also implemented a middleware to check if this user account is verified.

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If this user account is verified, then we can connect to move to the next middleware.

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But if the user account is not verified, we can through error and give it notice.

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And the next we display this error says that not allowed verify your account.

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So let's say that the user has to verify his or her account.

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Then you are going to call next to move to the next middleware.

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Now we have also this middleware in the pipeline.

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You can see how we are changing.

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Couple of many words before even get to the server.

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So many were like like a security or layers where we can use to implement any logic before a user get

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to the server.

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And let's say that this time around the user is an admin indeed.

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Then we are going to call next to move to the next media world.

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Finally, the user has been able to get into our server and the server returned the response back to

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the user.

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So we see how important middleware is, so we can implement millions of millions of middleware in the

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chain.

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The next video let's see how we can implement middleware.