HTTP Requests Using Telnet

So that we can get the most basic, no frills to look at HTTP, 0:00 we'll use some text-based interactions. 0:04 HTTP is a plain text protocol, which means that messages sent using HTTP 0:07 are directly readable, kinda like a text file on your computer. 0:11 A great piece of software to use for this purpose is called Telnet. 0:16 Telnet is a little piece of software that's designed for connecting to and 0:21 communicating with a remote device. 0:25 With Telnet, you aren't limited to communicating using HTTP, but 0:27 that's what we're gonna focus on here. 0:31 Let's get started. 0:34 You can install Telnet on your local machine if you like. 0:36 And there's plenty of instruction out there to get you going. 0:39 Check the teacher's notes for more. 0:41 Fortunately, you also have Telnet available to you in workspaces. 0:43 So, even though I'll be demonstrating the work in my terminal, you'll be able to do 0:46 the same using the console on the workspace that's linked to this video. 0:50 We'll be connecting with a web server at httpbin.org using Telnet, 0:54 httpbin.org is a service specifically designed for 0:59 testing HTTP requests and seeing the resulting responses. 1:03 To connect with this server using Telnet, I'll start by issuing the Telnet command. 1:06 Followed by the name of the host that we wanna connect to httbin.org, 1:11 followed by the port number. 1:16 This 80 is for port 80, and indicates a specific type of communication that will 1:18 happened with the device we're connecting to. 1:23 In our case, the type of communication that will be happening is HTTP messaging. 1:26 Think about this way, the host or 1:30 domain name of httpbin.org reside at some address. 1:33 Which is the address of a specific device or server, think of this server 1:36 is a house and it's address is called the internet protocol or IP address. 1:41 Now, once we've arrive at the house, let's say that there's several 1:45 people living there and each one speaks a different language. 1:49 We only speak one language, HTTP that is. 1:51 So we'll knock on the web server's door, which is door or port 80 by default. 1:55 As long as there's somebody in port 80, that is, 2:00 there's a web server at this address, we know that the person who opens the door 2:03 also speaks our language, which again is HTTP. 2:06 Great, so I'll hit enter to connect and then I'll send a request to get the root 2:10 using HTTP protocol version 1.1, 2:15 and follow it quickly with the host again. 2:20 And I'll hit enter twice. 2:24 A couple thing here, I have to specify the host again because it turns out that 2:26 at this address of where we connected, there might be several host. 2:31 For example, GoDaddy is a web host that will put many domains or 2:35 host onto a single IP. 2:39 Listing the host again in the httprequest.sent 2:41 allows the server to route it to the proper place with in the server. 2:44 Another thing, I said you'll have to quickly follow-up with the host. 2:48 I say quickly, because while using telnet, your may timeout. 2:52 There's nothing about HTTP that requires quickness, that's just part of Telnet. 2:56 Now, let me scroll up to where I made this request and explain what I did. 3:01 I made a request to get or fetch the content that is at the root. 3:06 That's why I'm using this single slash here. 3:11 And the protocol version I'm using of HTTP is version 1.1. 3:14 This entire line here is called the request line. 3:19 Which we'll discuss more in just a bit. 3:22 Making this whole request is like navigating to httpbin.org in your browser. 3:25 The response I got here is HTML as you see down below. 3:29 And the only difference is that when a browser sees HTML, 3:34 it's rendered by what's called the browser's layout engine. 3:37 But here in terminal, there's no layout engine. 3:40 In other words, the browser knows how to read HTML and make it look presentable on 3:43 the terminal, well, the terminal is text base so it just spits out the raw HTML. 3:46 Let's scroll down and 3:51 make another request to this server, this time requesting a different resource. 3:52 So, to reconnect to the server, I will telnet again to httpbin.org at 80. 3:56 And this time I will request the resource at /xml, 4:02 again using HTTP version 1.1. 4:07 And I'll list again the host. 4:11 Press enter twice, and there's our response. 4:14 Let's go back to this request line here. 4:19 I'm requesting the resource at /xml. 4:21 You may have used this slash notation to refer to directories in the past. 4:25 And this sometimes the case when communicating with web servers, 4:29 but a slash doesn't always refer to a directory. 4:32 So be careful here. 4:35 For now, simply think of it a resource at the address /xml on the host httpbin.org. 4:36 This resource identifier has a name, 4:45 it's called quite intuitively a uniform resource identifier, abbreviated URI. 4:47 It's not quite the same thing as a URL, which is a uniform resource locator. 4:53 We'll return to the similarities and differences later on. 4:58 Now in this case, the response that came back is XML which stands for 5:01 extensible markup language. 5:06 Instead of the response we got previously which was HTML or 5:09 hypertext markup language. 5:12 Httpbin.org has several different resources that it exposes for 5:15 you to test different things. 5:18 And this is one of them. 5:21 We can test HTML responses, and we can test XML responses among others. 5:22 Now, we can't just make any request to the server and expect a great response. 5:27 Let's scroll down and try another. 5:31 Let me clear the console here to give myself a clean screen. 5:34 Let's again telnet to httpbin.org at port 80, 5:39 and let's get the resource at /treehouse using 5:43 HTTP version 1.1 and again specifying the host. 5:48 I'm gonna hit enter twice. 5:56 And it doesn't take much scanning through the response to see that the server's 5:57 telling us that there is no resource that has the identifier/treehouse. 6:02 And you've probably seen this 404_NOT_FOUND message before. 6:06 Before we bring this video to a close, 6:12 let me quickly show you how to do this in workspaces. 6:13 If you open the linked workspace, you'll see a completely empty project. 6:16 You won't need to add any files to the project but 6:21 you will need to use the console here. 6:24 If you don't see the console, simply choose View, Show Console. 6:28 When the console is hidden, this option right here will say, Show Console. 6:33 Click it and it will come right up for you. 6:36 Now you're ready to start using Telnet. 6:41 So, just as before, you could start by connecting with Telnet. 6:42 Telnet httpbin.org port 80. 6:46 And we could get the root using HTTP version 6:50 1.1 at the host httpbin.org. 6:55 And there it is. 7:00 For any other work I do in the terminal, 7:02 you'll be able to do the same in workspaces. 7:04 So the choice is yours. 7:06