Software Engineering | Structure Charts

Structure Chart represent hierarchical structure of modules. It breaks down the entire system into lowest functional modules, describe functions and sub-functions of each module of a system to a greater detail. Structure Chart partitions the system into black boxes (functionality of the system is known to the users but inner details are unknown). Inputs are given to the black boxes and appropriate outputs are generated.

Modules at top level called modules at low level. Components are read from top to bottom and left to right. When a module calls another, it views the called module as black box, passing required parameters and receiving results.

Symbols used in construction of structured chart

1. Module
   It represents the process or task of the system. It is of three types.
   • Control Module
     A control module branches to more than one sub module.
   • Sub Module
     Sub Module is a module which is the part (Child) of another module.
   • Library Module
     Library Module are reusable and invokable from any module.

   

2. Conditional Call
   It represents that control module can select any of the sub module on the basis of some condition.

   
3. Loop (Repetitive call of module)
   It represents the repetitive execution of module by the sub module.
   A curved arrow represents loop in the module.

   

   All the sub modules cover by the loop repeat execution of module.

4. Data Flow
   It represents the flow of data between the modules. It is represented by directed arrow with empty circle at the end.

   

5. Control Flow
   It represents the flow of control between the modules. It is represented by directed arrow with filled circle at the end.

   
6. Physical Storage
   Physical Storage is that where all the information are to be stored.

   

Example : Structure chart for an Email server

Types of Structure Chart:

1. Transform Centered Structure:
   These type of structure chart are designed for the systems that receives an input which is transformed by a sequence of operations being carried out by one module.
2. Transaction Centered Structure:
   These structure describes a system that processes a number of different types of transaction.