What are the basic components of dialog program ? | ABAP Module Programming

• Screens (Dynpros)
Each dialog in an SAP system is controlled by dynpros. A Dynpro consists of a screen and its flow logic and controls exactly one dialog step.
• ABAP/4 module pool
Each dynpro refers to exactly one ABAP/4 dialog program. Such a dialog program is also called a module pool, since it consists of interactive modules.
What is a dynpro ? What are its components ?
• A dynpro (DYnamic PROgram) consists of a screen and its flow logic and controls exactly
one dialog step.
- The different components of the dynpro are:
Flow logic: Calls of the ABAP/4 modules for a screen
Screen layout: Positions of the texts, fields, pushbuttons, and so on for a screen
Screen attributes: Number of the screen, number of the subsequent screen, and others
Field attributes: Definition of the attributes of the individual fields on a screen.