174 Http cookies Session Handling Tracking Management Technique | Advance Java Servlet tutorial

Http cookies (Session Handling/Tracking/Management Technique):
- Cookies are small textual informations which allocates memory at client side(browser window or client machine) having the capability to remember client data across the multiple requests during a session.

- To work with cookies we need to the protocol HTTP and servlets of type HttpServlet.

- Cookies travel over the network along with request and response.

- Every cookies must be added to response.

There are 2 types of cookies:
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1) In Memory/per session cookies
2) Persistent cookies:

1) In Memory/per session cookies:
- No expiry time.
- Allocates memory on browser window.
- Once browser window is closed, these cookies will be destroyed automatically.

2) Persistent cookies:
- Contains expiry time.
- allocates memory in the files of client machine file system(Hard disk/SDD)
- Will be destroyed automatically once expiry time has been reached.




- Every cookie contains a name and allows one string value.

- Every cookie contains cookie-id and also remembers the web application/domain name for which it belongs to.

- Server side web resource programs of web application create cookies and adds them to response to send to client. So cookies allocate memory as string information at client side(remembering the domain name/web application name)

- Cookies go back to web application along with the request when browser window gives request to web application to which the cookies belong to.

- Cookies come to client from server/web application along with the response, as the values of special response headers called "set-cookie".

- cookies go back to the web application along with the request given by the browser window, as the special request header values called "cookie".

- At client side or browser window, we can see multiple cookies belonging to different domains.