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Let's take a look first at the handler interface here, the contract for the handlers.

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So as you can see, there is only one method here for handling requests.

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And by the way, you may recognize this code from the flyaway tutorial.

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So it's the same one.

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But I have adapted it for including the chain of responsibility pattern.

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So the handler interface will be implemented by our handlers.

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The authentication one is the first one and the authorization will be the second in the chain.

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So this is how the authentication handler looks like.

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It has a reference to the next item in the chain, which is the authorization handler.

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And for the handler requests does have a simple Sisso statement here, but it also will have a reference

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to the handler request submitted from the authorization object, as you can see here.

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So basically the check authorization method will have a reference, will call the handler request method

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that is being part of the handler interface here from the authorization handler.

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So basically here, what we want to attempt is to have an authentication and authorization for a user

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of an online shop before he or she may order stuff from from from this online store.

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So the code is untouched, the rest of the code, except for the client application, which now needs

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to start the process from the authentication part.

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So basically, here we have a call for the handler request from the handler, which in our case is the

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authentication handler.

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Then the request will be passed to the authorization handler, which is the second item in the chain,

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and after that, the rest of the code will be executed.

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So well, let's start this.

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So as you can see, the first message is authentication is successful and the next one is client authorized

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to use the system as a customer, which is the message that is printed out by the sender request method

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from the authorization handler.

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So that's it for the chain of responsibility pattern.

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Join me in the next video where we are going to discuss about the command pattern.