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HTTP Request Anatomy

Course video 7 of 57

The description goes here

This MOOC describes by example how to build cloud services via the use of object-oriented design techniques; Java programming language features; Java Servlets, the Java Spring Framework; and cloud computing platforms, such as Amazon Web Services. Due to the importance of building secure and scalable mobile/cloud platforms, this MOOC will not only show you how to build cloud services, but how to do so securely, scalably, and efficiently. Security and scalability topics will be woven into discussions of cloud service creation so that students learn, from the start, how to create robust cloud services.

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Compétences que vous apprendrez

Hypertext Transfer Protocol (HTTP), Servlets, Cloud Services, Web Application, Java Spring Framework

Enseigné par

Dr. Jules White
Associate Professor of Computer Science
Dr. Douglas C. Schmidt
Professor of Computer Science and Associate Chair of the Computer Science and Engineering Program

Transcription

[MUSIC]

Whenever a client sends a request to a server using

HTTP, that request has to have a very specific format.

I mean, just think about it, if you're that server

receiving all of these requests from all over the place.

You have to absolutely make sure that they all have the same format so

you can interpret them properly and figure out the right thing to do with them.

And that's why HTTP, very strictly specifies what the

format and the rules are for sending that request.

So let's talk about the Parts of a Request.

So we have our HTTP Request.

And, each HTTP Request has a number of critical, some mandatory

and some optional, parts that have to be sent to the server.

One of the first parts that has to be sent to the server is the Request Line.

And the Request Line specifies two really important things.

The first thing is it specifies the Request Method.

And the second thing that it specifies is the Resource.

That we want to take action on, which is typically specified as a Path.

So these are a request part.

Now, this is the key thing.

We're going to say, server, please go and take this action.

On this particular Resource.

But when that server gets that Request there's lots of cases where

it may have multiple options for how it goes and completes that request.

For example, let's say that we have a webpage on the server, and it's the

homepage of that particular web address, so you go to the Equivalent of google.com.

Well, sometimes the server needs help knowing some

information about the client that can help it to

complete that request, things like the language that

the client would like to receive the response in.

So, the next piece of the request is a series of Headers.

And what we can think of these is extra information to help the server.

And these were things like the language that

we would like the response to come back in.

Or the character set that we would like to see the response in, or the content type,

what we're sending back to the client so

it knows how to interpret it and process it.

Or possibly something like the cookies or small pieces

of data that were sent from the server to the

client in a past request that the client's now

providing back to the server to help it figure out.

Where it was or who this person is, and associate them with past requests.

So the Headers are the second key component of a request, and they provide

extra information to help the server figure

out the right way to process the request.

A final piece of information that can be part of an HTTP Request.

Is the Request Body, and the Body is any data

that the client is sending to the server, in order to help it complete the request.

Now, this an optional part of a request, and not a

100% required, but let's distinguish it a little bit from the Headers.

The Headers are meta information, things to help

it know the right way to process the request.

The Body is core data that is being sent to the server to process the request.

Now one way to think about this is in most cases.

If you didn't include the Headers, but you did

include the Body, the server could still process the Request.

It just may not give it back to you in the

format that you expected or exactly the way that you expected it.

But if you didn't include the Body and the server

needed the Body, it wouldn't be able to process the Request.

So the Body is the data the client is sending, that

the server absolutely has to have in order to complete that Request.

The Headers are extra information that the client is

giving the server to help it complete that Request.

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