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As usual, let's start with you, abstraction first, so we have this interface called service, which

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has only one method to be implemented, which will download the file that the client application needs.

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So let's go to the implementation.

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So we have this file download service, which has the name of the file as a property, which is set

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at the level of a constructor.

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And also we have the implementation for the download file.

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So for the sake of simplicity, I just stick with the system, this system, our printer and statements

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here so you can see that whenever this method is invoked, the name of the file will be printed as well

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as this this message over here.

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Let's take a look at the proxy.

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So the proxy is using composition it has and as a property, the file download service and also the

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file name.

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So basically, you construct the proxy as you do construct a file download service using the family

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and the download file will do some surprisingly, it will do some checks to see if the client has access

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to this resource and the access is granted, then it will go to check if the file download service is

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no.

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And if it's not, it will proceed to download the file.

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If it's if the file download services null, then it will create another instance of this resource here.

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So let's see the client application.

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So here we have a file, a very simple the text file and the service, as you can see, will take the

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form of a proxy service.

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So this will eventually let's allow the client application to download the needed files.

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So let's see this in action.

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So as you can see, the check is performed to see if the resource can be accessed, if the access is

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granted, then the file is loaded and then the file is being downloaded.

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This is a very, very simple implementation of the proxy pattern where you deal with some of the security

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aspects of the backend system that serves the files.

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Of course, this is this is not covered in this code here.

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There are just a very simple system of print and statements.

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But this is just to give you an insight on how to use the proxy in a real life scenario.

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So that's it.

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This was the last tutorial on the structural design patterns in the next module.

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We are going to discuss about the behavioral design patterns.

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So see you in the next video.