HTTP

Question 1

What is a client?

Answer 1

Client-server model is a distributed application structure that partitions tasks or workloads between the providers of a resource or service, called servers, and service requesters, called clients.

Often clients and servers communicate over a computer network on separate hardware, but both client and server may reside in the same system. A server host runs one or more server programs, which share their resources with clients.

A client (software) usually does not share any of its resources, but it requests content or service from a server.

Clients, therefore, initiate communication sessions with servers, which await incoming requests. Examples of computer applications that use the client-server model are email, network printing, and the World Wide Web.

Question 2

What is a server?

Answer 2

The server (software) component provides a function or service to one or many clients, which initiate requests for such services. Servers are classified by the services they provide. For example, a web server serves web pages and a file server serves computer files.

A shared resource may be any of the server computer’s software and electronic components, from programs and data to processors and storage devices. The sharing of resources of a server constitutes a service.

Question 3

Which HTTP method does a browser issue to a web server when you visit a URL?

Answer 3

An HTTP method, a verb (like GET, PUT or POST) or a noun (like HEAD or OPTIONS), that describes the action to be performed.

For example, GET indicates that a resource should be fetched or POST means that data is pushed to the server (creating or modifying a resource, or generating a temporary document to send back).

These verbs have no direct connection to any functionality

Question 4

What three things are on the start-line of an HTTP request message?

Answer 4

1. HTTP Method (a verb like GET PUT or POST) or noun (HEAD or OPTIONS) that describes the action to be performed
2. The request target (usually a URL)
3. The HTTP version

Question 5

What three things are on the start-line of an HTTP response message?

Answer 5

1. The protocol version (HTTP/1.1)
2. A status code, indicating success or failure of the request. Common status codes are 200, 404 or 302
3. A status text. A brief, purely informational, textual description of the status code to help a human understand the HTTP message.

Question 6

What are HTTP headers?

Answer 6

HTTP headers let the client and the server pass additional information with an HTTP request or response. An HTTP header consists of its case-insensitive name followed by a colon (:), then by its value. Whitespace before the value is ignored.

Question 7

Where would you go if you wanted to learn more about a specific HTTP Header?

Answer 7

MDN

Question 8

Is a body required for a valid HTTP request or response message?

Answer 8

The final part of the request is its body. Not all requests have one: requests fetching resources, like GET, HEAD, DELETE, or OPTIONS, usually don’t need one. Some requests send data to the server in order to update it: as often the case with POST requests (containing HTML form data).

Bodies can be broadly divided into two categories:

Single-resource bodies, consisting of one single file, defined by the two headers: Content-Type and Content-Length.

Multiple-resource bodies, consisting of a multipart body, each containing a different bit of information. This is typically associated with HTML Forms.