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Welcome back.

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In this video I want to talk a little bit more about HTP requests and how they work and what they look

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like

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sort of.

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So remember when I go to a u r l and my browser like this one here it doesn't matter what it is.

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And I hit enter the most important thing that happens there's a few steps but the most important step

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is that HTP request is sent to a particular server's IP address and then the server figures out what

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to send me and then it sends a HTP response back to me.

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So if there's one thing you take away from all of this stuff about how the Internet works and HTP it's

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the request response cycle you asked for a web page and you get one back to help us learn a little bit

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more about requests.

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We're going to use a tool called postman.

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It's a free tool and the Web site is get postman dot com and all we need to do is click on get it now

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and then it will take us to a Chrome extension page and then all you need to do is click this button

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to install it.

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And then once you have it installed you can launch the app.

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So this is postman here.

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I'll go ahead and make it full screen.

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The whole point of Postman is that it lets us make HTP requests and viewer responses and it's really

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for developers to understand how things are working possibly to debug something.

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If the data is not coming back the exact way that you're expecting it to.

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We're going to use that really as an educational tool and also use it for some debugging later on.

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Once we start building some more complicated apps.

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So before I actually demonstrated just want to remind you when I go to a web page and I click enter

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I can doing here that it's making an HTP request but that's not the only way to make a request with

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postman.

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We don't actually have a web page and I can still make HTP requests.

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I just want to reiterate that we can make requests from all different places.

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We can make them from a browser like Chrome.

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We can make them from an app like Postman.

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We can make them from our command line from the terminal.

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We can make them from other apps.

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We can make them from the backend or from an iOS app.

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So the idea of HTP requests are independent of browsers.

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Let's go ahead and make our first request.

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So when we make a request the most important part is the URL that we're making the request to which

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is Google dot com in this case we're just trying to replicate.

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When I go to Google dot com in my browser and I hit enter and then there's this choice here get post

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patch put delete all these different what we call each TTP.

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And these refer to different types of requests that we can make.

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We'll be seeing these a lot more and spending more time in particular with get Post put patch and delete

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.

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These are the ones are much much less important.

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I'll give you a very quick version of what they do.

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These just tell the server what we're doing with the request.

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What type of requests we're making if we're just retrieving information like retrieving the Google home

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page.

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That's a get request.

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If I am signing up for a web site or creating a new comment on Facebook or submitting a new reddit post

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or uploading those could be post requests where I'm posting new information to a database somewhere

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I'm sending some data along with my request versus a get request.

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Typically we're not sending much data along.

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We're asking for data to come back and then put in patch are used to update things or to edit them.

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So if I wanted to update the title of a Facebook image that I had uploaded after I had already posted

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it I could use a put a patch request.

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And of course the user doesn't decide on this ever.

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This is what the developer decides on and then we have a delete request which does what it sounds like

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when a server gets a delete request it expects that you're going to delete something.

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But what's most important is that this is all just a protocol.

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Remember that HTP stands for hypertext transfer protocol so it doesn't mean that just by sending a delete

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request something is automatically deleted.

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What it does mean is that it's a protocol.

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So if I say that this is a delete request we should expect that it will delete something.

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So again very high level overview will be going into depth with all of these here.

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These first five verbs and the different types of requests.

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When we actually make a server that handles them.

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But to start I'm just going to make a get request to Google dot com and that's all we need to do.

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And if I clicked send I get a few things back.

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There are three important parts of every response the first one is the body of the response.

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That's like the payload.

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That's what is being sent back.

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So the HD mal the C Ss and the javascript in this case.

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And this is the H.M.S. s and Javascript of the Google homepage.

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This is what we would see if we went to Google and did view page source just like this there we go.

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So our browser just takes that and makes it look nice.

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Then the other thing that we get back is the headers.

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So the headers are like the meta data about the response so they contain a few pieces of information

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.

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The important ones that I'll point out are the content type.

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So this says OK just to warn you I'm sitting back HMO because we can actually send back other types

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which we'll see later on.

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All that we've seen so far though is HMO.

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Also the date and the time when this response happened when it was sent back.

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And then this thing called status which we also get up here.

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So the status code is a third big piece of information and it's just a number.

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You've probably seen them before.

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Most importantly 404 if you've ever seen before or for ever a status code.

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It's just part of the protocol of HTP.

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It's a standardized way of saying that the request that you made is good I'm going to send back status

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code 200 because I found the page you're looking for.

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Who'd you go.

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But then if we sent a request to a page that doesn't exist the server need to wait to respond back to

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us.

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So there are different status codes and they each mean different things.

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We'll be working with them again later on in the class.

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So we have the body which is the content that's being sent back the headers which contain meta data

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about the response.

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And one of those pieces is the status code and that's just a number that represents the status of this

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whole request slash response cycle.

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So demonstrate this with another Web site like Reddit dot com just like that and we'll also make you

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get request every time I load up my browser and I go to a you or I'll like Reddit dot com.

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That is a get request.

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I cannot make a post request from my browser search bar.

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We can make a post request using a h l form which we mentioned briefly when we talked about forms and

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we will be doing that.

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For now we're just focusing on get requests.

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Earlier I mentioned when we send a request like a get request we're usually asking for information back

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and when we send a post request we're trying to add date data to a database.

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So there's some sort of payload in the request where I'm sending in the information they want to be

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added.

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For instance the information to make and you post on Facebook or on Reddit.

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But we still can send some data with a get request.

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I'll give you a quick example.

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If I go to Reddit outcome which I have opened here and I do a search.

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So let's say I want to search for Corgies and I hit enter.

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Notice what happens up here.

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So it's Reddit dot com slash search question mark.

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Q equals Corgies.

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What type of requests do you think I make when I hit enter right here.

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Well I just told you a few minutes ago that the only type of request we can make is a get request from

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the browser's search bar or the nav bar.

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So this is a get request but we're also sending a little piece of information along with it which is

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our search term and it's still a get request.

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We're not adding Corgies to a database anywhere.

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We're not posting anything new to this application or to the database.

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We're purely retrieving information retrieving posts that have Corgies in their title.

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This is how we can send some data along with a get request.

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It's called the query string.

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So I can add in parameters here as many as I want something like name equals cold and it won't do anything

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but the server will get that and if it was expecting a name if read it was expecting a name parameter

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it would see that name is equal to Colt.

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So I can tag as many of these as I want.

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I can do another one here.

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City equals Assef and I can keep changing these together but they don't mean anything except for q which

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is something that the Reddit server is expecting on the search page.

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Reddit dot com slash search.

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When we make a request it's expecting queue to be equal to the search term.

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One last thing about the query string is that it always starts after a question mark and that we separate

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the key value pairs so q equals a corgi name equals cold.

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They're separated by an ampersand to actually send one of these.

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You can go back here and I can click on programs here and what harams let me do is I can add in your

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parameter key and value.

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So here let's say that I want Q To be equal to cats you can see postman makes this little request for

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me and adds the query string in.

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So now if I hit send here making a get request to read it dot com Q equals cats.

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I'm not going to get back the search results because this is on Reddit dot com slash search not just

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read it dot com.

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So now if I go back and do Reddit dot com slash search Q equals cats.

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This is making a request to the search page and saying we're searching for cats.

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Let's quick send and go to body here.

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We get a bunch of age Chimo and I'll scroll through and it's hard to see because there's so much information

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but we have references to cats in the hd a male and a postman we can actually click on preview and we

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can see that we get information about cats.

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So these are all posts about cats.

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It's not perfect.

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The C Ss isn't showing up but it's at least the HCM mouth that we can view.

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To summarize all of this we kind of covered a lot here.

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First thing was that you can make a request from all sorts of different places.

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It's not only in your browser.

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Next thing is that every request has a verb or a type and we've been making get requests only so far

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but soon we'll see post requests when we actually have a database going and we want to let users sign

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up or submit a new comment or something like that.

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They'll be sending a post request and our server is going to expect to post request and do something

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when it gets supposed request.

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So get requests are for retrieving information searching often just getting a home page or getting any

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page that doesn't involve sending data but we can still send data with the Get request.

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Usually it's when we're sending like a search query or another parameter about how we want the data

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to be sorted or what order it should be in.

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But the key is that we're still not adding anything to the database.

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This doesn't change read it's database.

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It's just asking for things that have cats in the title and all that logic happens on Reddit it's and

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written in Python and Reddit spec and is going to see that we ask for Redditt dot com slash search as

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a get request and then it has some code that will run when they get requests is made to read it dot

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com slash search and in that code it will then look for the variable queue instead of the query string

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.

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Will take the corresponding value cats retrieve all the posts all the comments or whatever it does that

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match cats and then send me back.

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All this HD mail will be returning to postman later on in this course as a way of debugging some of

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our own applications.

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Next up we're going to start talking about node