WEBVTT

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-: In the last section,

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we spoke about some big issues

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that kind of came up as we were going

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through a single container deployment.

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In this section, we're gonna start talking about

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the application that we're gonna make,

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to give you more experience

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on building a multi-container application.

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So, one application that uses many different containers

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or many different services,

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to achieve whatever its goal is.

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Now, to show you what we're gonna build,

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I wanna first give you a very quick overview

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on a side topic.

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So, this right here is a diagram

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of the Fibonacci sequence.

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The Fibonacci sequence is a sort of, computer science topic.

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You'll see this very commonly come up in computer science

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or programming interviews.

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The Fibonacci sequence is a series of numbers.

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So, the sequence goes 1, 1, 2, 3, 5, 8, 13, 21, and so on.

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So, it continues on much further than this.

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Any value, or any index inside the Fibonacci sequence

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can be calculated by taking the previous two values

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and adding them together.

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So, for example, to calculate this value right here,

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we will look at the previous two values of, 1 and 2.

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If you add together 1 and 2, that gives you 3.

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And so, that gives us the next value in the sequence.

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Then to calculate the next value,

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we would do, 2 plus 3,

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add those together and you get 5.

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The next value would be 3 plus 5, that gives you 8.

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5 plus 8 gives you 13, 8 plus 13 gives you 21, and so on.

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In a computer science or a programming interview,

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a very common question that you might get is,

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write a function that calculates the Fibonacci value

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at a particular index.

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So, for example, if I asked you to give me the value

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of the Fibonacci sequence at index 7,

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you would have to calculate the number 21.

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And if I asked you to give me the value at index 5,

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you would need to calculate 8, and so on.

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So, the application that you and I are going to be making

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is essentially going to be a

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fancy Fibonacci sequence calculator.

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And we're going to build this, in a just,

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absolutely over-the-top complicated fashion.

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You could absolutely build a function, like,

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just three or four lines of code

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that will calculate any number in the Fibonacci sequence.

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But again, to give you an example of a

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multi-container deployment,

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we're going to make a crazy, crazy, over-the-top,

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way overcomplicated version of a Fibonacci calculator.

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Just to give you more experience

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with a multi-container deployment.

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All right.

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So, let's take a look at the mock-up for our application.

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All right. So, here's the app right here.

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We're going to present the user

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with a little form at the top, that's gonna ask them

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what index they want us to calculate.

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So, for example,

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a user might enter in right here 7,

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and then they would click on submit.

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When the user clicks on submit,

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we're gonna take that index

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and then we're gonna have some,

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back-end processes or some servers

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that's going to calculate

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the Fibonacci value at index 7.

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And so eventually, our application for index 7,

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will need to calculate out the value 21.

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After the user submits that number right there,

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we would add the number 7 onto this list of indices

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that our application has seen.

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So, I would expect to see 7 added on there,

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and then we should eventually also

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calculate the appropriate value for index 7.

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And so eventually,

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I should see some line entry here of,

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for index 7, I calculated 21, like so.

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All right. So, that's the application,

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essentially a fancy Fibonacci calculator.

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And again, we're gonna make this just,

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over-the-top complicated,

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way more complicated than it needs to be,

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to give you a good example of a multi-container deployment.

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Now, the reason that we're doing a

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Fibonacci calculator here, as opposed to like,

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a blog, or like a Twitter application,

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or something like that,

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is that I didn't want you to have to focus on

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the actual application implementation details.

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I didn't want you to have to worry about

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learning JavaScript, or learning authentication,

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or any of that stuff.

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And I just wanted you to be able to focus

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a hundred percent on the

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docker and deployment side of things.

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And so, that's why we are using a rather, kind of,

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simplistic topic here as a subject of our application.

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Now, let's take a quick pause right here.

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Now that we've got a better idea

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of the application that we're gonna make,

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we'll come back to the next section,

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and we'll start talking about the overall architecture

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of this application.

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So, another quick break,

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and I'll see you in just a moment.