5 levels of software development

There are five levels of clutch, namely –

Content binding. When the module can directly turn to the content of another module, change it or refer to it, this is called the binding of content.

General connection – when several modules have access for reading and writing to some global data, this is called a common or global connection.

Managing communication. Two modules are called managers if one of them solves the function of another module or changes the course of execution.

Stamping communication – when several modules have a common data structure and work with another part of it, this is called stamp.

Data connection. Data connection is when two modules interact with each other through data transmission (as a parameter). If the module transmits the structure of data as a parameter, then the acceptor of the module should be used by all its components.

Ideally, no coupling is considered the best.

Design check

The result of the software development process is design documentation, pseudo -codes, detailed logical schemes, process diagrams and a detailed description of all functional or non -functional requirements.

The next stage – the implementation of software – depends on all the results mentioned above.

Then it becomes necessary to check the weekend before moving on to the next stage. The sooner any error is detected, the better it may or cannot be detected before testing the product. If the output data of the design stage is presented in the formal form of the recording, the appropriate tools for verification should be used, otherwise for verification and confirmation, you can use a thorough analysis of the project.

Thanks to the structured inspection approach, reviewers can detect defects that can be caused by the passage of some conditions. A good design review is important for good software design, accuracy and quality.

Tools for the analysis and design of software

Software analysis and design includes all actions that help transform the specification of requirements into implementation. Specifications of requirements determine all functional and non -functional expectations from software. These specifications of the requirements are presented in the form of readable and understandable documents, to which the computer has nothing to do.

Analysis and design of software is an intermediate stage that helps to transform the requirements understandable to a person into real code.

Let’s look at several tools and design tools used by software developers:

Data flow diagram

Data flow diagram is a graphic presentation of data flow in the information system. It is able to display an incoming data flow, an outgoing data flow and saved data. DFD does not say anything about how the data pass through the system.

There is a noticeable difference between DFD and block diagrams. The block diagram depicts the control flow in software modules. DFD display a data flow in the system at different levels. DFD does not contain control or branching elements.

Types of DFD

Data flow charts are either logical or physical.

Logic DFD – this type of DFD is concentrated on the system process and data flow in the system. For example, in the banking system of software, as data moves between different objects.

Physical DFD – this type of DFD shows how the data stream is actually implemented in the system. This is more specifically and close to implementation.

DFD components

DFD can represent a source, destination, storage and data flow using the following set of components:

DFD components

Objects – objects are the source and place of purpose of information. Entities are represented by rectangles with appropriate names.

The process – actions and actions taken with data are represented by rectangles with round or round edges.

Data storage. There are two options for storing data: it can be presented in the form of a rectangle with the absence of both smaller sides or in the form of a rectangle with an open side with the absent one by only one side.

The flow of data – data movement is shown by arrows. The data movement is indicated from the base of the arrow as a source to the direction of the arrow as a destination.

DFD levels

Level 0 – DFD of the highest level of abstraction is known as DFD level 0, which depicts the entire information system in the form of one diagram that hides all basic parts. Level 0 DFD are also known as DFD levels of level.

Level 0

Level 1 – DFD level 0 is divided into a more specific DFD level 1. Level 1 DFD displays the main modules in the system and the flow of data between different modules. Level 1 DFD also mentions the main processes and sources of information.

1st level

Level 2 – at this level, DFD shows how the data is transmitted inside the modules mentioned at 1.

A higher level DFD can be transformed into more specific DFD lower levels with a deeper level of understanding if the desired level of specification is not achieved.

Level 2 – at this level, DFD shows how the data is transmitted inside the modules mentioned at 1.

A higher level DFD can be transformed into more specific DFD lower levels with a deeper level of understanding if the desired level of specification is not achieved.

Structural diagrams

A structural diagram is a diagram obtained from the data flow diagram. It represents the system in more detail than DFD. It breaks the entire system into lower functional modules, describes the functions and subunctions of each system module in more detail than DFD.

The structural scheme is a hierarchical structure of modules. A certain task is performed on each layer.

Here are the symbols used in the construction of structural schemes –

Module – represents the process, subprogram or task. The control module is branched into several windows. Library modules can be used again and call from any module. SC modules

Condition – it is represented by a small diamond at the base of the module. He shows that the control module can choose any subprogram on the basis of a certain condition. SC condition

Jumping – an arrow shows inside the module showing that the control element will jump in the middle of the submodule. SC Module Jump

Loop – a curved arrow represents a loop in the module. All the windows covered by the cycle repeat the module. SC loop

The data flow – a directed arrow with an empty circle at the end represents a stream of data. SC Dataflow

A control flow – a directed arrow with a filled circle at the end represents a control flow. SC Controlflow

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