Software design encompassed 4 distinct but interrelated activities that are given below: interface  design,  architectural design,   data design and  procedural design.  Each of these design activities has been finished a comprehensive design model exists for the software establishment. Data design translates him data objects described in the analysis model into data structures which reside within the software. The attributes which describe data objects the relationships among data objects and their use within the program all influence the choice of data structures.

Architectural  design  technique  presented  in  this  lecture  use  information  flow  characteristics define in the analysis model to derive program structure.  The Data Flow Design is mapped into a structure which allocates control to input, processing and output along 3 divided factored module hierarchies.Transaction mapping is applied when a single information item causes flow to branch behind one of many paths. The  Data Flow Design  is  mapped into  a  structure which  allocates control to  a  substructure that  evaluates and acquires a transaction. The substructure controls all potential processing actions   based on a transaction