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In this chapter, you looked at implementing the interface tier of an application. You implemented the user interface through a traditional Windows Forms-based application front end. Along the way, you took a closer look at the classes and namespaces of the .NET Framework used to implement rich Windows Forms-based user interfaces. In the next chapter, you will revisit implementing the UI tier of a .NET application. Instead of implementing the GUI using Windows Forms, you will implement the GUI as an ASP.NET application using Web Forms. Along the way, you will take a closer look at the namespaces available for creating Web-based GUI applications and the techniques involved in implementing the classes contained in these namespaces.

In this chapter, you looked at implementing the interface tier of an application using a Web Form-based frontend. Along the way you took a closer look at the classes and namespaces of the .NET Framework that are used to implement Web Forms-based user interfaces. You were also exposed to data binding Web server controls, in particular, the GridView control. In the next chapter, we will look at web services. Web services enable developers to expose the services implemented by their applications using open standards. Using web services, heterogeneous applications can communicate through XML-based messaging via open protocols such as HTML.

In this chapter, you looked at creating and consuming web services. Web services provide a programmatic interface to your application. Using web services, applications based on disparate technologies can easily exchange data using a standard set of messaging and transport protocols. Web services also allow businesses to easily exchange data and provide services for partners. Although you did not add a web service to the case study, you can easily see how an office supply retailer could offer valuable services to business customers. For example, they could build an ordering service that allows the placement of orders. They could also provide a web service that tracks the processing of an order. Web services are becoming an integral technology for enterprise-level application development and business-to-business data exchange. For the latest information on web services, visit the World Wide Web Consortium (W3C) web site at www.w3c.org.

While a SQL query is at the center of every data operation—SELECT, INSERT, UPDATE, or DELETE—you have many ways to get that SQL query defined and executed, and its results examined. You can do almost anything you like as long as you form the SQL correctly and obey the rules of the database you’ve defined.

You shouldn’t regard the examples in these chapters as the dogmatic way to do any one particular task. Their purpose is to present various techniques that you may or may not choose to use in your own pages. Whether you use any one block of code is up to you, but you do at least now know where some code works and where other code doesn’t work.

In the next chapter, we’ll move away from writing code to modify the database and see that the GridView (and its siblings the DetailsView and FormView) allows you to write pages that will automatically propagate the changes to the database, provided that you specify the correct INSERT, UDPATE, and DELETE queries.