DataFlex Web Framework Symposium – Part 7.5 Web Framework Modal Objects

2. DataFlex Web Framework Symposium – Part 7.5Web Framework Modal Objects John Tuohy Development Team www.dataaccess.com

3. Modal Objects • The web framework supports Modal objects • Supports: • Message Boxes • Modal Dialogs • We provide the classes and interface to make this all work • There are special web considerations

4. Handling Events • The client/server event cycle • The client • Generates an event. If a server event it sends a request to the server • The server • Attaches process and synchronizes • Sends the event to the corresponding DataFlex object • Which, might change web property values and queue client actions • Generates a response and detaches from the process • The client • Handles the response by synchronizing web properties and executing required client actions

5. Modal Objects // Create a Hello World Button Object oButton is a cWebButton Set psCaption to “Save" Procedure OnClick Send ShowInfoBox of oWebApp "Hello world!" End_Procedure End_Object 5

6. Modal Objects Modality using a windows-like approach Object oButton is a cWebButton Procedure OnClick Integer eConfirmMode // invoke modal dialog which asks question Get ShowYesNo of oWebApp "Are you sure?" "Confirmation" to eConfirmMode // handle the response If (eConfirmMode =MBR_Yes) Begin Send DoAction End End_Procedure End_Object This will not work, can you see why?

7. Handling Events

8. Modal Objects • With web modal dialogs you are going to need an extra client-server round trip • OnClick request is sent to server • Server tells client to display the modal dialog and disconnects • Upon completion client must send a message back to the server with the results • The Server processes the results and disconnects Q: How does the client know what message and object to callback in step 3? A: A callback object and message must be passed in step 2.

9. Modal Objects Modality using the web approach – this works Object oButton is a cWebButton Procedure ConfirmResponse Integer eConfirmMode If (eConfirmMode = cmYes) Begin Send DoAction End End_Procedure // Publish the response method WebPublishProcedure ConfirmResponse Procedure OnClick Integer eAnswer Send ShowYesNo of oWebApp (Self) (RefProc(ConfirmResponse) "Are you sure?" "Confirmation" End_Procedure End_Object

10. Modal Objects • Message Boxes • ShowInfoBox • Used to show an information box • Single Ok button, no callback • ShowYes • Used to show a Yes/No dialog • You pass the callback object and callback message • ShowMessageBox • Used or custom multi-button message boxes • You pass the callback object and callback message

11. Modal Objects • Modal Dialogs • Based on cWebModalDialog class • Is invoked by sending Popup passing the callback object • Upon completion the client sends a server requests which sends OnCloseModalDialog to the callback object Procedure OnCloseModalDialog Handle hoModalDialog String sAnswer Get GetAnswerName of hoModalDialog to sAnswer Send ShowInfoBox ("Your name is " + sAnswer) End_Procedure Procedure OnClick Send InitializeDialog of oDemoQuestionDialog "Question" "What is your name?" Send Popup of oDemoQuestionDialog Self End_Procedure

12. Modal Dialogs The Invoking Object Object oAskQuestion is a cWebButton Set psCaption to "Ask Name" Procedure OnCloseModalDialog Handle hoModalDialog String sAnswer Get GetAnswers of hoModalDialog to sAnswer Send ShowInfoBox ("Your name =" + sAnswer) End_Procedure Procedure OnClick Send InitializeDialog of oDemoQuestionDialog "What is your name?" Send Popup of oDemoQuestionDialog Self End_Procedure The Modal Dialog Object oDemoQuestionDialog is a cWebModalDialog // user inteface goes here Function GetAnswers Returns String String sReponse WebGet psValue of oResponseFrm to sResponse Function_Return sReponse End_Function Procedure InitializeDialog String sQuestion WebSet psCaption of oQuestionLbl to sQuestion WebSet psValue of oResponseFrm to "" End_Procedure End_Object

13. Modal Objects • To summarize • The web framework support modal popup objects by using callbacks • Supports: • Message Boxes • Modal Dialogs • An extra request/response cycle is required • A callback mechanism is required to make this work • Special interfaces are provided to make the callback mechanism easy to use and secure

14. The End