All language subtitles for 012-App Overview-git.ir

Now that we've seen some notes on how we handle communication with micro services it's time to actually

start writing some code.

So in this video we're going to take a look at a mockup of the application we're going to build.

To better understand these asynchronous communication patterns if we look at the mockup just a couple

of quick notes.

First off the goal this application is to really just get a taste of micros services architecture.

We're going to work on a much larger more comprehensive project later on INSIDE THE COURSE.

This first project is really just meant to get your feet wet and healthy just kind of expose you to

some of these critical issues.

We're also gonna have a goal inside this project of building as much as possible from scratch.

So we're going to build out every last service by hand.

We're going to build out the event broker by hand going to build out as much as we can by hand just

to get really good idea of what is going on.

Because of that because we're building this stuff from scratch I would not recommend using this project

as a template for future micros services projects.

The reason for that is that usually we're going to use a lot of packages to implement a lot of this

stuff as opposed to doing it by hand.

So on real projects you're going to want to use some packages as opposed to these kind of manual implementations

that we're going to do.

Again we're going to work on a very large project later on that's going to be a very serious professional

grade project.

So you are going to see how to use those other packages and whatnot.

Ok so enough of that.

What are we going to build.

You're gonna make a very simple little application that's all about making posts like blog posts or

something similar and allowing users to comment on them.

So any user first comes to application we're gonna show a form like this where user can create some

kind of post we're going to say that our posts only have titles there's not going to be any kind of

body or anything like that.

So a user might type inside of your my post and then hit submit once they do so we're then going to

display the post they just created down here at the bottom the screen.

That would be the post that was just created we'll show that title The Post will show the number of

comments so as associate with it and we'll also have a little form right here to add some comments to

that individual post.

So for example I might type inside of here I'm a comment and then click on cement and if I did so I

should see this post counter right here or the comment counter incremented by 1 and I should also see

the comment listed out right underneath the actual title and then of course we can add in as many posts

as you want so we could go back up here to the top put in post number two.

Hit submit and then we should see post number two.

Down here up here.

And of course we show bill to add in comments like I'm a comment to that one as well.

Hit submit and see that comment up here right there.

So in total this application is pretty straightforward but I think that you're going to be kind of surprised

at the level of complexity that we're going to encounter.

Even for this very simple and straightforward application.

All right.

Now we've got an idea of what we're going to build.

Let's start to break this thing down and consider some of the different technical aspects of it.

So the first thing that we need to think about is what services we are going to create for this part

of the course.

And for a little bit going on into the future right now we're going to say that for every different

unique resource that we have inside of application we're going to create a separate service.

So in our application I would say that we have two different types of resources.

We have posts which are these things we're creating down here at the big blue boxes and then we have

comments which are the things right here the bullet points that are tied to individual posts.

So in total we really have two different resources.

So we're going to think about creating two different services.

We're going to have a postal service that is in charge of storing all the different posts we have and

retrieving them giving them back to us.

And we'll have a common service that is going to be in charge of handling comment creation and listing

all the different comments out so we start to think about these different services.

The first thing we want to really do is really picture the different goals or responsibility of each

service.

So like I just said with a post service we probably want the ability to create a post and to a list

all posts and for comments we probably want the ability to create a comment and list all comments.

Now there's already some hidden complexity inside of here.

The Postal Service is going to be pretty straightforward but if you really start to think about this

and really drill down the common service is going to probably be a little bit more challenging than

you might think at first glance.

The reason for that is that the comment service whenever we create a comment we're going to really be

tying a comment to a post.

So there's going to kind of be a dependency of sorts between reading a comment and having some knowledge

of what posts exist.

So we're going to have to apply one of those asynchronous or synchronous communication patterns we just

discussed to make sure that users can only create comments that are tied to a very specific post.

In addition whenever we tried to list out some comments we probably don't want to just get all the comments

that exist in the universe.

Instead we probably want to somehow retrieve just comments that are associated with some very particular

post.

So in other words if we retrieve the top 10 most popular posts inside our application for example we

probably only want to get comments tied to those specific top 10 posts.

So even though I say right here list all comments well once again there's probably gonna be some kind

of dependency inside of here where the comments that we're retrieving need to somehow be tied to the

actual posts that we're retrieving as well if not that makes sense right now.

That's totally fine.

All I mean to say is that this application is going to be a little bit deceptively challenging even

though it looks like it's really simple and straightforward in nature OK.

So now we've got an idea of what we're going to build.

And it's clear that we're going to run into some challenges along the way quick pause right here and

we'll start to write some code in the next video.