To demonstrate the basic principles of n-tier development, the BackOffice® Developer's Guide (BDG) presents a version of the "Hello World" application commonly used as the first demonstration when learning a new programming language. The application calls a Component Object Model (COM) component built in Microsoft® Visual Basic® to retrieve the phrase "Hello World" from a Microsoft SQL Server™ database in the default language of the client's machine. The database currently contains the phrase in English, French, and German.
As illustrated in the following screen shot, the application first sends the phrase "Hello World" to the client in plain HTML. Next, as a result of executing some JavaScript code on the client, it displays "Hello World FROM JAVASCRIPT." Then, VBScript on the server executes and sends "Hello World FROM ASP to client computer's IP address." Finally, the application finds the client computer's default language and uses it to search for the phrase "Hello World" in that language in a SQL Server table, sending the result back through the business-services tier to the client.
The following topics discuss the architectural design and implementation of the Hello World application:
These topics discuss every line of code in the application. For your convenience, we also include complete source code without any accompanying description. For the Active Server Pages scripts, Visual Basic code, and SQL scripts, see Hello World Code.