What are the different methods of session management in servlets

Question

I am just starting with Advanced Java. Could you please help me with session management techniques

Answer 1

Session is a conversational state between client and server and it can consists of multiple request and response between client and server. Since HTTP and Web Server both are stateless, the only way to maintain a session is when some unique information about the session (session id) is passed between server and client in every request and response.

Some of the common ways of session management in servlets are:

1. User Authentication
2. HTML Hidden Field
3. Cookies
4. URL Rewriting
5. Session Management API

Comments

@frankie can you explain about these?

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Cookie 

A cookie is a small piece of information that is persisted between the multiple client requests.

A cookie has a name, a single value, and optional attributes such as a comment, path and domain qualifiers, a maximum age, and a version number.

URL Rewriting

n URL rewriting, we append a token or identifier to the URL of the next Servlet or the next resource. We can send parameter name/value pairs using the following format:

url?name1=value1&name2=value2&??

A name and a value is separated using an equal = sign, a parameter name/value pair is separated from another parameter using the ampersand(&). When the user clicks the hyperlink, the parameter name/value pairs will be passed to the server. From a Servlet, we can use getParameter() method to obtain a parameter value.

HTML Hidden Field

In case of Hidden Form Field a hidden (invisible) textfield is used for maintaining the state of a user.

In such a case, we store the information in the hidden field and get it from another servlet. This approach is better if we have to submit form in all the pages and we don't want to depend on the browser.

Let's see the code to store value in hidden field.

<input type="hidden" name="uname" value="Edureka">  

Here, uname is the hidden field name and Edureka is the hidden field value.

Session Management API

Session Management API is built on top of the above methods for session tracking. Some of the major disadvantages of all the above methods are:

• Most of the time we don’t want to only track the session, we have to store some data into the session that we can use in future requests. This will require a lot of effort if we try to implement this.
• All the above methods are not complete in themselves, all of them won’t work in a particular scenario. So we need a solution that can utilize these methods of session tracking to provide session management in all cases.

That’s why we need Session Management API and J2EE Servlet technology comes with session management API that we can use.