- Introduction to HTTP 1:22
- Building a Case for HTTP 2:41
- Intro to HTTP 2 questions
- HTTP Requests Using Telnet 7:08
- HTTP Request Format 3:01
- HTTP Headers 1 question
- HTTP Response Format 3:42
- HTTP Response Format 1 question
- Sending Data with a GET Request 4:11
- Sending Data with a GET Request 1 question
- Sending Data with a POST Request 5:57
- Sending Data with a POST Request 1 question
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HTTP Requests Using Telnet
7:08In this video, we'll get a firsthand, unobscured look at HTTP requests and responses using a command-line tool called Telnet.
So that we can get the most basic,
no frills to look at HTTP,
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we'll use some text-based interactions.
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HTTP is a plain text protocol,
which means that messages sent using HTTP
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are directly readable,
kinda like a text file on your computer.
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A great piece of software to use for
this purpose is called Telnet.
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Telnet is a little piece of software
that's designed for connecting to and
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communicating with a remote device.
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With Telnet, you aren't limited
to communicating using HTTP, but
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that's what we're gonna focus on here.
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Let's get started.
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You can install Telnet on your
local machine if you like.
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And there's plenty of instruction
out there to get you going.
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Check the teacher's notes for more.
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Fortunately, you also have Telnet
available to you in workspaces.
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So, even though I'll be demonstrating the
work in my terminal, you'll be able to do
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the same using the console on
the workspace that's linked to this video.
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We'll be connecting with a web
server at httpbin.org using Telnet,
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httpbin.org is a service
specifically designed for
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testing HTTP requests and
seeing the resulting responses.
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To connect with this server using Telnet,
I'll start by issuing the Telnet command.
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Followed by the name of the host
that we wanna connect to httbin.org,
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followed by the port number.
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This 80 is for port 80, and indicates
a specific type of communication that will
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happened with the device
we're connecting to.
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In our case, the type of communication
that will be happening is HTTP messaging.
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Think about this way, the host or
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domain name of httpbin.org
reside at some address.
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Which is the address of a specific
device or server, think of this server
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is a house and it's address is called
the internet protocol or IP address.
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Now, once we've arrive at the house,
let's say that there's several
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people living there and
each one speaks a different language.
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We only speak one language, HTTP that is.
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So we'll knock on the web server's door,
which is door or port 80 by default.
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As long as there's somebody in port 80,
that is,
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there's a web server at this address,
we know that the person who opens the door
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also speaks our language,
which again is HTTP.
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Great, so I'll hit enter to connect and
then I'll send a request to get the root
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using HTTP protocol version 1.1,
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and follow it quickly with the host again.
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And I'll hit enter twice.
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A couple thing here, I have to specify
the host again because it turns out that
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at this address of where we connected,
there might be several host.
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For example, GoDaddy is a web host
that will put many domains or
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host onto a single IP.
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Listing the host again
in the httprequest.sent
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allows the server to route it to
the proper place with in the server.
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Another thing, I said you'll have
to quickly follow-up with the host.
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I say quickly, because while using telnet,
your may timeout.
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There's nothing about HTTP that requires
quickness, that's just part of Telnet.
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Now, let me scroll up to where I made
this request and explain what I did.
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I made a request to get or
fetch the content that is at the root.
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That's why I'm using
this single slash here.
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And the protocol version I'm
using of HTTP is version 1.1.
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This entire line here is
called the request line.
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Which we'll discuss more in just a bit.
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Making this whole request is like
navigating to httpbin.org in your browser.
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The response I got here is
HTML as you see down below.
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And the only difference is
that when a browser sees HTML,
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it's rendered by what's called
the browser's layout engine.
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But here in terminal,
there's no layout engine.
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In other words, the browser knows how to
read HTML and make it look presentable on
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the terminal, well, the terminal is text
base so it just spits out the raw HTML.
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Let's scroll down and
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make another request to this server,
this time requesting a different resource.
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So, to reconnect to the server,
I will telnet again to httpbin.org at 80.
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And this time I will request
the resource at /xml,
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again using HTTP version 1.1.
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And I'll list again the host.
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Press enter twice, and
there's our response.
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Let's go back to this request line here.
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I'm requesting the resource at /xml.
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You may have used this slash notation
to refer to directories in the past.
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And this sometimes the case when
communicating with web servers,
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but a slash doesn't always
refer to a directory.
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So be careful here.
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For now, simply think of it a resource at
the address /xml on the host httpbin.org.
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This resource identifier has a name,
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it's called quite intuitively a uniform
resource identifier, abbreviated URI.
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It's not quite the same thing as a URL,
which is a uniform resource locator.
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We'll return to the similarities and
differences later on.
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Now in this case, the response that
came back is XML which stands for
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extensible markup language.
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Instead of the response we got
previously which was HTML or
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hypertext markup language.
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Httpbin.org has several different
resources that it exposes for
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you to test different things.
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And this is one of them.
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We can test HTML responses, and
we can test XML responses among others.
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Now, we can't just make any request to
the server and expect a great response.
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Let's scroll down and try another.
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Let me clear the console here
to give myself a clean screen.
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Let's again telnet to
httpbin.org at port 80,
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and let's get the resource
at /treehouse using
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HTTP version 1.1 and
again specifying the host.
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I'm gonna hit enter twice.
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And it doesn't take much scanning through
the response to see that the server's
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telling us that there is no resource
that has the identifier/treehouse.
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And you've probably seen this
404_NOT_FOUND message before.
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Before we bring this video to a close,
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let me quickly show you how
to do this in workspaces.
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If you open the linked workspace,
you'll see a completely empty project.
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You won't need to add any
files to the project but
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you will need to use the console here.
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If you don't see the console,
simply choose View, Show Console.
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When the console is hidden, this option
right here will say, Show Console.
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Click it and
it will come right up for you.
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Now you're ready to start using Telnet.
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So, just as before,
you could start by connecting with Telnet.
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Telnet httpbin.org port 80.
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And we could get the root
using HTTP version
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1.1 at the host httpbin.org.
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And there it is.
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For any other work I do in the terminal,
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you'll be able to do
the same in workspaces.
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So the choice is yours.
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