WRRC and Java

The HTTP Request Lifecycle

1. Local Processing :
   • Your browser extracts the: “scheme”/protocol, host, optional port number, resource path, and query strings.
   • Now that the browser has the intended hostname for the request, it needs to resolve an IP address.
   • then the browser look through its own cache of recently requested URLs, the operating system’s cache of recent queries, your router’s cache, and your DNS cache.

2. Resolve an IP -If the cache lookup fails (we will assume it does), your browser fires off a DNS request using UDP.

   -Your request will now have to travel many network devices to reach its target DNS server.

3. Establish a TCP Connection

   • delivery and ordered data transmission. done using a sequence number for every byte sent.

   • TCP connections are opened using what’s known as a three-way handshake.

   • concurrent communication along the connection, which is also known as full duplex communication.

4. Send an HTTP Request

   • Send a request made up of a “request line”, request header, and a body. The header of the request is made up of pairs in the form name:value . Two consecutive pairs indicate the end of the header section.

   • The request follows a similar routing procedure, with the difference being that using TCPs magic sequence number powers.

   • Once the server receives the request, processes it, and finds the resource being requested, it generates an HTTP response.

   • Once the response is generated, the server responds to the request. At the TCP layer, the client receives the first data packet, the first byte of which should contain the HTTP response header.

5. Tearing Down and Cleaning Up

   • The client sends a FIN packet, to which the server responds, and then generally sends a FIN of its own, which the client responds to. The client then waits for a brief timeout, during which it cannot accept new connections, to prevent delayed packets from previous connections arriving during subsequent activities on the port.

   • At this point, the browser begins processing what it has received. If it is an image, data, or other media file that is being consumed by some application inside the browser, a variety of things can happen.

Simple HTTP Request

1. Creating a Request .
2. Adding Request Parameters.
3. Setting Request Headers.
4. Configuring Timeouts.
5. Handling Cookies.
6. Handling Redirects.
7. Reading the Response.
8. Reading the Response on Failed Requests.
9. Building the Full Response.