Tag Archives: ASP session objects
In this post you will learn what is session object in ASP and how it is used?
The session object is used to store the information of a user session and to change its settings.
Session is usually when a user opens a particular application on a system, do some alterations on it and then close it. The system that you are using recognizes you and knows when you open and close the application. But, if we look for same recognition of user over internet, then there is a problem, because the web server does not recognize the user and has no information about its activities. This is because the HTTP address cannot maintain state.
So, the solution to this issue is provided by the ASP. It creates a unique cookie for every user and is sent to the system user is using. This cookie contains the information which actually provides the identification of the user. The session object is basically this interface.
In other words, session object is used to store user information and change the settings for the user session. The variables which are stored in a session object contains the information about single user and it can be accessed by every page in a particular application. The information which are usually stored on session variables are name, id and the user preferences. The server will always create a new session object for every user which is automatically destroyed when the session is finished.
The session for any user starts at three occasions; when a user has requested the ASP file and the Session_OnStart procedure is included in Global.asa file, when any value is stored in a session variable, when the uses has requested an ASP file, and the <object> tag is used to instantiate an object with session by a Global.asa file.
Any user session will end if he / she has not refreshed the web page in the application for a given time. This time is usually 20 minutes by default. But for some reason you want to change this wait or timeout interval to short or long period than you have to use the property known as Timeout property.
For example, consider a following example, in which we have set the timeout interval of 25 minutes:
The example below sets a timeout interval of 5 minutes:
But what if you want to end the session suddenly, then you will have to use the method known as Abandon. Consider the following example:
But we do not know when the user is going to end his / her session. The session ending time is unpredictable from the user side i.e. we do not know that the last request of the user was the final request or not. Thus, you do not know how long you need to keep the session alive. If you wait too long for the user to continue the session then it will use more of your resources which is not practical. On the other hand, if the session is stopped too soon than the user might have to start gain because when we stopped the session the server deleted all of the information of user session. Therefore, determining and setting a right timeout interval is a challenge. Therefore, we recommend to only store small amounts of data in the session variables.
In the next post, you will learn how to retrieve, store and remove the session variables. You will also learn how to loop through the content and static object collections.
The object which stores information or change settings of a user session is known as Session Object.
A session is the duration in which user opens an application, performs some changes in it and then closes it. During this session your computer knows everything about the opening of an application, changes you made in it and the closing of an application. But the server does not know anything about the session of an application because HTTP does not keep the information of this sort.
ASP solves this problem by using the interface of Session object. ASP basically creates a special cookie and sends it to the user computer to identify the user. This is known as Session Object.
Session Objects comprises of different variables which store information about the single user. But this information is available to every page of an application. Few common type of information stored in session objects are name, id and the user preferences. But the server destroys the session object after creating a new session object.
You must be wondering when a session starts? The session starts when
- any user requests an ASP file and there is a Session_On Procedure in the Global_asa file.
- There is any value stored in the session variable.
- any user requests an ASP file and there is a <Object>Tag in the Global_asa file to instantiate the session object.
The next question which comes in mind after this is When a session ends? So, the answer is that if the user is not using an application for a default period of time than the session will expire. By default this time is 20 minutes. This time can be changed by using the “Timeout” Property of the session. Following is an example where you can change the default time to 40 minutes:
But if ending the session immediately is needed then you can use “Abandon“ property of session. Following is the property that shows the syntax to end the session immediately:
Now the issue is when to end the session. For example you are using an application for past 20 minutes. Then you stop using it for like an hour. In the meantime this application is using loads of resources on the server for no use. So to reduce the resources, if the server shuts the session like after the 5 minutes( you have not been using the application). Then you would have to start again if by any chance you come back sooner than an hour. Therefore to find the right time to end the session is quite difficult and unpredictable. So, to avoid this issue we can store few variables in the session object.
The next post will explain about Storing, Removing and Retrieval of session variables. Also it will explain the procedure to loop the content collection and the Static Object collection.
For more visit next posts in this category.To go back to Contents of this tutorial: ASP Active Server Side Scripting Contents