Reading-notes

WRRC and Java

The HTTP Request Lifecycle:

• HTTP 1.1 request,

  not a persistent connection, but it could act as a good jumping-off point for HTTP/2 and persistent connection requests.

some various HTTP methods:

• Local Processing : depending on the application making the request.

• Resolve an IP:

  adding entries in the local hosts file on a computer.

• Establish a TCP Connection:uses a three-way handshake:

  1. SYN: The active open is performed by the client sending a SYN to the server.
  2. SYN-ACK: In response, the server replies with a SYN-ACK.
  3. ACK: Finally, the client sends an ACK back to the server.

• Send an HTTP Request:

  An HTTP client sends an HTTP request to a server in the form of a request message which includes following format:

• A Request-line.

• Zero or more header (General

  Request

  Entity) fields followed by CRLF.

• An empty line.

• Tearing Down and Cleaning Up :

  At this point, your 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.

• Well, that is it, that is the multi-layer lifecycle of a single HTTP request!

steps for example:

1. a way of performing HTTP requests in Java:

   by using the built-in Java class HttpUrlConnection.

2. HttpUrlConnection:

   The HttpUrlConnection class allows us to perform basic HTTP requests without the use of any additional libraries. All the classes that we need are part of the java.net package.

3. Creating a Request:

   We can create an HttpUrlConnection instance using the openConnection() method of the URL class.

4. Adding Request Parameters:

   we have to set the doOutput property to true, then write a String of the form param1=value¶m2=value to the OutputStream of the HttpUrlConnection instanc

5. Setting Request Headers:

   Adding headers to a request can be achieved by using the setRequestProperty() method.

6. Configuring Timeouts:

   HttpUrlConnection class allows setting the connect and read timeouts.

7. Handling Cookies:

   The java.net package contains classes that ease working with cookies such as CookieManager and HttpCookie.

8. Handling Redirects:

   We can enable or disable automatically following redirects for a specific connection by using the setInstanceFollowRedirects() method with true or false parameter.

9. Reading the Response:

   by parsing the InputStream of the HttpUrlConnection instance. To execute the request, we can use the getResponseCode(), connect(), getInputStream() or getOutputStream() methods.

10. Reading the Response on Failed Requests

If the request fails, trying to read the InputStream of the HttpUrlConnection instance won’t work. Instead, we can consume the stream provided by HttpUrlConnection.getErrorStream().

1. 11. Building the Full Response :

   It’s not possible to get the full response representation using the HttpUrlConnection instance. we can build it using some of the methods that the HttpUrlConnection instance offers.