Structured design

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Structured Design ( SD ) is a design pattern in software technology according to Edward Yourdon and Larry Constantine, which supports modular design in order to describe the interactions of higher-level modules in addition to the pure functional hierarchy . SD is used with Structured Analysis (SA) in software engineering.

approach

The structured design builds a bridge between the technology-neutral analysis and the actual implementation . In the structured design, technical boundary conditions are introduced and the rough structure of the system is determined from a technical point of view. It thus represents the content-related planning of the implementation.

The methodology uses structure diagrams to display functional modules hierarchically and thus shows the individual call hierarchies of the modules among each other. A functional module consists of one or more functional abstractions. This in turn represents one of the first abstraction mechanisms and groups several associated program commands into units (functions). An example would be computing the square root sqrt (x). The user does not need to know any details about the implementation, just applies the function. To do this, he needs a corresponding interface description, which is just as much a part of the structured design as the creation of the module hierarchy. A functional module has no internal memory , i.e. it does not contain any data (private data) that are only visible in the module. It can only store information in global data (for example when calculating a random number). Later methods based on this, such as modular design (MD) , introduce abstract data types and data objects.

use

Object-oriented analysis and design have displaced structured methods in many areas. In banks, insurance companies and in the embedded sector , many system developments are still taking place with structured methods. In particular in the field of mobile business , computer systems are often used which have limited resources for which an object-oriented implementation with its overhead is too expensive. Furthermore, within the framework of the integration of existing applications within the framework of EAI , subsystems often have to be implemented that cannot be implemented with object-oriented languages. Therefore, object-oriented analysis and design, which are otherwise very widespread worldwide, would constitute incorrect implementation preparations.

Function-oriented method

Tasks are broken down into sub- tasks top-down and then mapped onto the modules (principle of modularization).

Descriptive means are structure diagrams in which the modules and the connections between modules are shown.

example

The Customer Management menu is divided into the Customer form and the Customer report .

Customer form is again subdivided into update and sales discount , customer report in print preview and print .