Using the Object Model as a Road Map

While being able to create a page dynamically is a nice feature, the real power of Active Server Pages comes from its ability to create web-based applications. These applications allow the user to perform tasks that go beyond simply requesting pages. The logic and structure to create these applications are laid out in the object model.

We can use the object model as a road map that lays out:

q     Where information should be stored in our applications

q     How information specific to a single user can be tracked

q     How to set up client pages to send the appropriate information to the server for it to dynamically build a page

q     How to dynamically build a page, using all of the features that ASP provides, and then send that page back to the client

In the next few chapters, we will be walking through this landscape in detail and build up the expertise needed to put together an application using Active Server Pages.

Summary

In this chapter, we have introduced the concept of objects. For our purposes, an object is a programmatic tool that enables us to access a physical item, or a set of associated data. An object is described by its interfaces. These interfaces are broken into three categories:

q     Properties – a property's value holds data that describes an attribute of the object.

q     Methods are used to have the object perform some task for us.

q     Events let the object notify us that something has happened and can also be raised to make something happen and can contain code that we write that can be executed.

In learning how to develop with objects, we have seen how to:

q     Set and retrieve information from the object's properties

q     Call the methods of an object

With the concepts of objects well in hand, we introduced the Active Server Pages object model. These seven objects encapsulate the functionality offered by the ASP server.

q     The Server object provides basic functionality across the web server.

q     The Application and Session objects provide the application functionality that is not present in a basic web server.

q     The Request and Response objects are used to interpret the information sent by the client and then construct the HTML page that will be sent back in response.

q     The ObjectContext object, which is used to control transactions within a web page.

q     The Error object that handles any ASP-generated errors

By understanding the relationships of these objects to one another, we can start to build true applications by using the power of Active Server Pages. The next few chapters will begin to show us how.