What is HTTP?

• HTTP Protocol Definition

  HTTP Protocol Definition

  HTTP is an application-layer protocol used to transfer information between networked devices. It runs on top of other layers of the network protocol stack.
• What are HTTP functions?

  What are HTTP functions?

  HTTP, also known as the hypertext transfer protocol, offers a standard and reliable method for users to send and receive data over the internet. As a client-server protocol, users must send data requests to the server through a user agent, typically a web browser. A connection request forwarded from the user agent to the server is called the HTTP request. After receiving the connection request, the server analyzes it and sends a reply message to the client containing details regarding the request status, known as the HTTP response. This stateless protocol has two different versions: HTTP/1.0 and HTTP/1.1. The former is an older protocol and requires a new connection setup for every data exchange, whereas the latter can support multiple data exchanges in a signal connection. The stateless nature of this protocol restricts both client and server from holding any web information after connection termination.

  Outlined below are some critical functions of this connectionless protocol:

  • Caching: The HTTP server supports the caching option to enhance the website performance and user experience. The responses sent by the server against different GET requests of clients can be cached only. The server also decides the duration for which a client browser can cache a particular response. Support for the private and shared cache is also available in this stateless protocol.
  • Client authentication: This connectionless protocol also supports basic authentication to secure confidential documents on the server. The server includes the “WWW-Authenticate” header in its response message as part of this security mechanism. This header contains information regarding the authentication scheme, allowing the client to connect to the server by providing relevant user credentials. However, the basic authentication scheme in the HTTP protocol isn’t secure. It doesn’t encrypt user credentials; therefore, combining it with Trusted Content Services (TCS) is recommended for improved security.
  • Traffic management: The HTTP proxy server filters the malicious network traffic directed towards the primary server. As an intermediary server, it sits between the user agent and the primary server to block suspicious connection attempts. It also supports load balancing and content caching for enhanced website performance.
  • Session management: HTTP cookies allow the server to uniquely determine a client who makes multiple connection requests to the server. Since HTTP considers every data request independent, cookies provide a powerful way to keep track of user preferences and behavior during multiple related requests. The HTTP server utilizes the “set-cookie” header field to direct the client browser to deposit cookies while navigating a website. The “set-cookie” header has additional attributes, such as domain, path, and expires, helping the client browser understand the scope of cookies. For instance, the domain parameter helps identify the websites for which the cookie is valid.
• What are the HTTP methods?

  What are the HTTP methods?

  GET and POST are the two popular HTTP methods helping retrieve and send data to the server, respectively. The GET method is preferred when the data requested from the server contains textual information only. The information requested from the server is also available as a query string in the URL.

  Outlined below is an example of a URL containing GET information:
  http://www.dummywesbite.com/action.php?name=XYZ&weight=70

  The text following the question mark in the given URL denotes the HTML form data sent to the server using the GET method. The amount of data you can forward to the server using the GET method depends on the maximum URL length supported by your web browser. Though GET is the standard HTTP method, it isn’t suitable for handling sensitive information as the data is displayed in the URL and can be bookmarked easily.

  In contrast, POST is a secure method for forwarding sensitive information to the server. Instead of URL parameters, it embeds the confidential data in the body of the HTTP request for improved security. Additionally, it doesn’t support bookmarking, making it a comparatively safer option for sensitive data transfers. Unlike GET, it doesn’t restrict the amount of data you can forward to the server. Web admins generally choose the POST method when large data files need to be uploaded to the server.
• What’s in an HTTP request?

  What’s in an HTTP request?

  An HTTP request is a message forwarded by the client to execute a particular operation on the server, such as data modification and retrieval. Request line, request headers, and request body are the three core constituents of an HTTP request.

  • Request line: contains methods, such as GET and POST, which specify the operations needing to be performed on the server. For instance, the POST method explains that a user wants to upload a particular file on the server (data modification). The request line also specifies the HTTP version and the URL of the request.
    
    Outlined below is an example of a request line:
    GET /dummy/images HTTP/1.1
    In this example, the GET method indicates the user wants to fetch a particular resource from the server, which is available at the “/dummy/images” location.

  • Request headers: are available below the request line in the request message. These headers provide supplemental information related to the request, allowing the server to understand the client’s communication preferences. For instance, with a header like “accept-language,” the server can determine the language in which a client or user wants to read a requested document. The list of standard headers and their usage methods are available in the HTTP specifications.
  • Request body: The last part of the request involves the entity-body. It’s optional but helpful when transmitting ancillary information to the server. For example, when using the POST method, the body of the request typically contains the data transmitted to the server. In contrast, the GET method doesn’t require an entity-body as its main aim involves fetching a specific resource from the server.
• What are HTTP request headers?

  What are HTTP request headers?

  The HTTP request header acts as a request modifier as it highlights the client’s specific requirements while accessing a particular resource from the server. The structure of a request header is straightforward: it contains the header name and corresponding value. A colon is used as a separator between the two parameters.
  

  Outlined below is an example of a request header:
  If-Unmodified-Since: Wed, 8 Dec 2021 11:40:12 GMT
  

  It indicates the client will access a particular resource from the server only if it’s unaltered since the last date and time highlighted in the header field. A client can specify multiple headers in the request for enforcing various conditions while requesting a particular resource from the server. General header, request header, and representation header are the three headers commonly available in a request. A general header can serve as a request or response header depending on the requirements. On the other hand, the request header can alter the client request by specifying additional requirements. The representation header highlights the content type and encoding status of the data available in the entity-body.
• What’s in an HTTP response?

  What’s in an HTTP response?

  Once a request message arrives, the server performs the expected operations and sends an acknowledgment message back to the client. This reply message is known as the HTTP response. The response message sent by the server has a standard structure so a client can easily interpret it. Status line, response header, and response body are three main vital aspects of a response message.

  Outlined below is a detailed explanation of these core elements:

  • Status line: The protocol version, HTTP status code, and status text are the main constituents forming the status line. The version denotes the HTTP specification the server is complying with while sending the reply message to the client application. A status code is a numeric value containing three integers offering clarity on whether the request is successful or not. On the other hand, the status text is a short, informational summary helping decode the status code’s meaning.
    Outlined below is an example of the status line:
    HTTP/1.1 404 Not Found
    The server uses the HTTP/1.1 version while communicating with the client application in this example. The presence of status code “404” means the server can’t locate the resource requested by the client. The server uses different status codes to notify the clients about the current position of their requests, such as informational and client error responses.
  • Response header: contains the supplemental data the server forwards to the client while sending the reply message. A server typically uses multiple response header fields such as content-type and content-length. These headers are placed between the response line and the response body and are similar to other HTTP headers. Response headers are also helpful in suggesting the recommended actions to a client for quick request approval after a connection error.
  • Response body: is available underneath the response headers and contains the files or data requested by the client while making a connection request to the server. However, some of the responses from the server don’t have a message body as their status codes are satisfactory to respond to client requests. For instance, the status code “204” highlights a server has already acted upon the client request, and there’s no need for any ancillary data in the request body. In case of an unsuccessful request, the response body also helps the client identify the reasons for the error and the recommended actions for successful request approval.
• What’s the difference between HTTP and HTTPS?

  What’s the difference between HTTP and HTTPS?

  Both HTTP and HTTPS (the “S” stands for Secure) are reliable network protocols enabling the client application and the server to establish a connection link for information exchange. With the HTTP protocol, the communication line between the client and the server isn’t ciphered, making it less secure for sensitive information transfer. Additionally, the data exchanged between both parties is available as plain text, making it easier for attackers to steal it.

  In contrast, HTTPS offers a more secure, reliable, and trusted method of information exchange between the user agent and the server by enabling Secure Socket Layer (SSL) or Transport Layer Security (TLS) encryption. By enabling HTTPS protection, a website can prevent attackers from viewing the sensitive data exchanged between the web application and the server. However, HTTPS is slower than its counterpart as it requires more time and computational resources to encrypt the communication link between the client and the server.