Guide to the ASP Application Object

This guide is a aimed at being a quick overview to the Active Server Pages Application Object, its properties and its methods.

What is the Application Object

We all know what a computer application is. It's a program that accomplishes a specific task. In terms of web development, an application is no different with the exception of that a web application may (or may not), consist of a number of server scripted web pages. In the case of Active Server Pages, an ASP application is a set of ASP files that work together to perform a number of tasks.

The ASP Application object is used to tie these files together, and allow every ASP page in the application access to a set of global variables. It works in pretty much the same way as the ASP Session Object does, with the exception of that a variable within the Application object is not just accessible to any ASP web page in the application, but it is also shared by every user/session connected to the application. With Session variables on the other hand, all ASP pages have access to them but they are only valid for the user/session that created them.

The ASP Application Object should be used wisely, and used to hold information that will be common to a number of pages, such as database connection strings and urls of items such as shopping cart pages etc. This is beneficial because it means you only have to reference the appropriate variables on any page you need them, and when you change the contents of the variable it effects every page in the application, and in ever session automatically.

The ASP Application Objects Collections

The ASP Application object only has two collections to speak of, and those are as follows:

Contents
The contents collection is the same as that used in ASP Session Objects. It is used to access the application objects variables that have been added to the application via scripting methods.
StaticObjects
This static objects collection holds a list of static HTML objects that have been assigned to the application object with the html <object> tag.

The ASP Application Objects Methods

There are relatively few methods for the ASP application object, all of which are listed below:

Contents.Remote(index | reference)
This method is used to remove an item from the Contents collection. You can specify either an index number or a string reference as a parameter. The referenced item will be removed from the collection.
Contents.RemoveAll
This method is used to clear out the Contents collection.
Lock
This function is used to lock the application object so that no other users/sessions can modify its contents. You will need to call this function before modifying the values of any Application variable so that other users/sessions can modify it at the same time.
Unlock
This function is used to unlock the Application so that other users and sessions can once again start modifying variables. Call this function after you have previously called the Lock function.

The ASP Application Objects Events

The ASP Application object has two events associated with it. Information about these events can be found in the ASP tutorial for using the Global.asa file.