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Cookies

We can read and write cookies directly from our application by using the Cookies collections of the Response and Request objects. We can control the existence of the cookies we write by setting the Expires property. This means that, unlike the Session object, we can keep information alive after the browser has been terminated so that the information can be used the next time the browser is started and our application accessed. Cookies that stay alive like this are stored permanently (until they expire, that is) on the user's hard drive, so even if the user has accepted a cookie, there is no absolute guarantee that it will still be there the next time the browser program is run.

Another mechanism that can be used to transfer data back and forth between the server and browser is to set and query the URLData property of the Web class. This property works by storing extra information with URLs written in pages that are sent out to the browser. If any of these URLs are activated in the browser and initiate a request on the server, the URLData property of the Web class is set to reflect the data that is sent back.

Conclusion

We've investigated many of the features available to Visual Basic developers who want to (or have to) develop Web applications. In the process, we've produced the skeleton of a functioning application-nothing to set the world on fire, but it's a start nonetheless.

This IIS Application template allows Visual Basic developers to use existing skills to create Web applications. However, to really start developing Web applications, developers should have a good knowledge of HTML, even if they don't have to write the code that is displayed in browsers. A knowledge of HTML will help Visual Basic developers get the most of the limited interaction between browser and server. Web developers also need to understand and control the lifetime of their applications and the data they rely on for operation. This definitely needs more careful consideration than for a standard Visual Basic project. Knowledge of ASP will also stand Web developers in good stead, since Web applications created with Visual Basic are based on this technology. The core objects within a Web class (Request and Response) are ASP objects, which is certainly a good reason to learn about ASP.

To produce powerful Web applications, the developers will almost certainly have to move away from a purely server-based application with the thinnest of clients and incorporate client-side scripting, DHTML, ActiveX components, and so forth, in their overall application code. This adds even more to the areas of knowledge that Visual Basic developers must enter.

No doubt that Visual Basic 6, with its IIS Application template, will kick start the development of many Web-based applications.

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