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Lesson 9: DataFlex Web Applications and conclusion

Next to windows applications, DataFlex can also be used to build web applications. With web applications a lot of technologies come together and it all starts with the DataFlex application server. This is a windows service that runs in the background of your machine on the server, it hooks into the Microsoft internet information server. This is the actual webserver that handles the traffic. Within DataFlex you can do the entire handling of an HTTP-request by using the cWebHttpHandler. You can also build SOAP web services that can be called using JSON and XML. You use the cWebService for that. Classic ASP objects can be used by publishing objects using cWebAspClassicObject.


Web Application Framework

Build rich web application that include: control classes, wizards and the designer. This all works by including a Java Script Engine into your page that communicates with a DataFlex web service. The Java Script Engine contains the implementation of the controls and it supports multiple themes that determine the look of your application. When you use the web application framework, the structure of your application looks pretty similar to a windows application. The structure of objects is also pretty similar. When you write your won code and you work with properties, you usually work with web properties. There a different types of web properties:


Demonstration  

  1. Projects > new > Mobile Web project > OK
  2. The ‘Assign Application Information’ panel comes up. You need to give DataFlex elevated rights to be able to create the application. Because it needs to register the application in the internet information server.
  3. The Web Application Name is the name that identifies the application within the Web Application Framework.
  4. For IIS, leave ‘Website’ to ‘Default Website’ > OK
  5. Now it’s going to copy7 in the Java Script Engine and the CSS into the AppHtml Folder. It also generates the DataFlex code that comes with the web application.
  6. In the code explorer you can see it generated a oWebApp object, inside of this object you will find several panels and menus.
  7. Open up the WebApp Designer panel by pressing F7
  8. Objects selected in the code explorer will be highlighted in the designer panel.
  9. Add a new view to your application.
  10. Create New > Web View > OK
  11. Name the object, in this case: DemoWebView > OK > Yes.
  12. To make a new button: Class palette > click & drag cWebButton onto the designer.
  13. Scale down the button in the designer by grabbing the corner and drag it inwards.
  14. In the properties panel change the psCaption to “Hello World!”
  15. Go to the Events tab and press: OnClick.
  16. Close the designer panel for now.
  17. Add the following line of code to your application (line 28)
Send ShowInfoBox "Hello world!" "Hi there!"

18. Compile (F8)

19. Run (F5)

This will open up the browser window, with a log-in screen. The default username and password is: Guest.

20. Click the dropdown menu > View > DemoWebView.

21. Click the “Hello World!” button, an info box should pop-up.

22. OK to exit.

Debugging in WebApp goes the same as under windows, by placing breakpoints in the code. Working with properties in WebApp is slightly different.

23. F7 to open the WebApp Designer.

24. Drag another cWebButton from the class palette into the WebApp Designer.

25. Change the scale if desired.

26. Go to the properties panel and change psCaption into: Change Value!

27. Go to the events tab and press OnClick.

28. Add the following code to your application.

29. Compile

30. Run (F5)

31. Sing in > Dropdown menu > View > DemoWebView

32. Click the new button ‘Change Value!’

See the changes made behind: Label 1