8.3.5 Render, Submit, Branch, Repeat

At runtime, the model-driven APEX engine breathes life into your page and component definitions using a simple lifecycle: render, submit, branch, and repeat.

• Wizard Example Page Lifecycle
  When a user clicks Onboard New Employee in your app's navigation menu, the APEX engine renders page 43 based on its page definition. As the user enters data and clicks buttons in the page, branches control what page to show next. Optional computations, validations, and processing let you create flows of pages for any business process.
• Computing Values on Render or Submit
  Define computations to set the value of a page item or application item.
• Validating Submitted Data
  Define validations to enforce the correctness of submitted data before saving it. You create them in the Validating execution point of the Processing tab in your page.
• Custom Processing on Render or Submit
  Create page processes for custom behavior in the Pre-Rendering phase of the Rendering tab, or in the After Submit or Processing phases of the Processing tab. The Execute Code process type lets you include custom code to performs any business logic required, while you can use other native process types to handle other common tasks declaratively.
• Best Practice Use of Invoke API
  For easier maintenance and testing of your custom code, Oracle recommends writing most business logic in functions and procedures of a PL/SQL package. You can then engage these packaged program units from one-line statements or expressions in your pages, or invoke them declaratively using an Invoke API page process.
• Making Almost Any Element Conditional
  Add a Server-side Condition to almost any element in your APEX app to control whether APEX renders or runs it.