Interacting with the app

• When using web applications, end-users don’t just type URLs and wait for the result
• It is very common to have other forms of interactions
  • Following links
  • Filling in forms
  • Clicking buttons
    Each time the user navigates to a new page, or submits data do the server, a new request / response cycle starts

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Link Widget

• Links and Buttons have similar behaviors
• Links can enclose other widgets
• Visually more flexible than Buttons

On Click: Either submits a request to call an Action or navigates to a Screen Method property determines how data is submitted to the Server
Destination property can be set to a:

• Screen Action
• Destination

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Button Widget

Navigate Screen Lifecycle

Uses HTTP GET Method

• Requests a specific resource
• Does not submit data to the server
  • Parameters are sent and displayed in the URL
  • Form Input values are not sent in the request
    Browser displays the Destination URL
    Link / Button Destination can be:
• Target Screen
• External URL

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Submit Screen Lifecycle

Uses HTTP POST Method
Submits data to the server in the request

• Upload a file
• Send Form Input fields data

Browser shows URL of the Screen that handles the submit request
Link / Button Destination can be:

• Screen Action (submits to current Screen)
• Target Screen
• External URL

With the Submit Method, the Destination can be a Screen Action
● Runs when the Button / Link is clicked
A Screen Action has a flow of statements that are executed in order
● Has access to all elements in the Screen scope
○ Widgets
○ Preparation elements
○ Screen Variables
● The last node of the Action has impact on the Screen lifecycle

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Finishing the Screen Action

The last widget of a Screen Action flow greatly influences the lifecycle
There are several possibilities
● Stay on the same Screen
○ End, Download (of a file)
● Navigate to a Screen
○ Destination, Current Screen, External URL
● Raise an Exception

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Submit to the current Screen

The application stays in the same Screen in both cases:

• Preparation of the Screen runs
• Entire Screen will be rebuilt
  What’s the difference?
• End Node :: Values of Screen Variables and Widgets are preserved
• Destination (Current Screen) (Chuyển hướng trang 203)
  ○ Values of Screen Variables and Widgets are reset to their default values

Download Widget

Allows the end-user to download a file

• Can be saved
  Download widget properties
• File Content: Expect binary data
• File Name: Text of the file name
• Save to Disk: Or just display the file
  Ends the Action Flow
• There can be no other statements after it
• Preparation does not run again

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HẾT.