By Kochnev Victor (vakochnev@edu.hse.ru)
The detail design stage plays a key role in software development, because at this stage high-level architectural solutions are transformed into specific technical details that determine the structure and logic of the system. Choosing the appropriate detailed design method can significantly affect the success of a project, ensuring reliability, flexibility and compliance with requirements. Given the variety of approaches, from strict formalized methods to more flexible approaches, developers are faced with the need to take into account many factors: the complexity of the project, deadlines, resources, team characteristics and domain.
The purpose of the work is to consider the existing detailed design methods, their advantages, disadvantages and criteria for choosing the appropriate approach for specific conditions
There are many detailed design methods, and each of them is suitable for solving various tasks. It is important to understand that the choice of approach should be determined by the specifics of the project and its requirements.
Test Driven Development (TDD) is a method where tests are written before writing the main code. This process begins by creating tests that describe the functionality of the system, and then developing code to pass these tests. This approach promotes strict compliance with functional requirements and reduces the number of errors. An important feature of TDD is the iterative process: developers first create tests, then implement the minimum amount of code that satisfies these tests, and finally perform refactoring.
Type Driven Development (TyDD) is based on using the capabilities of the type system of the programming language for the design and implementation of the system. Types act as a tool that helps to formalize and verify the correctness of the relationships and behavior of system components at the compilation stage. This approach is especially effective in systems with high data complexity, where strict typing helps developers avoid mistakes.
Behavior Driven Development (BDD) expands testing ideas, focusing on describing the behavior of the system using scenarios that are understandable to both developers and business analysts. In this approach, scenarios that express the behavior of the system in natural language play a key role. Syntax is often used, for example, “Gherkin”, which allows you to set requirements in a format that is accessible to all team members, regardless of their technical background.
Domain Driven Design (DDD) is focused on modeling complex domains. This method is based on in-depth research of business processes in order to create software systems that reflect the real world and business logic as much as possible. One of the key features of DDD is the concept of “bounded context”, which helps to manage the complexity of the system by dividing the domain model into smaller and independent parts.
Feature Driven Development (FDD) offers an iterative process that focuses on the development and integration of individual functionality. This method is especially effective for large teams, as it allows you to break a project into small, easily manageable parts, which simplifies both coordination and control.
Model Driven Development (MDD) focuses on using models as a central element of design. The models describe the structure and behavior of the system, and then are automatically converted into source code. One of the features of MDD is the ability to reuse the created models, which significantly increases the efficiency of the team.
Each of the methods has its own strengths that make it useful in certain contexts.
TDD provides reliable test coverage and early error detection. It helps to improve the quality of the code and simplifies the maintenance process, since developers initially create a system that meets strict tests. In addition, this method allows you to increase the team's assurance in the stability of the system when making changes. In practice, this is especially important for projects that involve a long development cycle and frequent iterations, where changes in one component can affect the behavior of other parts of the system.
TyDD suggests simulating movements that require projection to determine the use of a strict strategy. This makes the system more predictable and makes it easier to work with complex data. Developers get the opportunity to carry out strict verification of the logic even before the program is launched. This method is especially useful when creating complex software solutions, such as financial systems or big data analysis systems, where errors can have significant consequences.
BDD improves communication between technical specialists and business analysts through scenarios that are understandable to both sides. This speeds up the coordination of requirements and simplifies the control over the implementation of functionality. Transparency of the process helps to avoid many mistakes associated with a misunderstanding of the tasks. Moreover, this method reduces the likelihood of “surprises” in the project, since the teams can agree on the desired behavior of the system in advance.
DDD contributes to the creation of a system that meets the needs of the business, facilitating the work of both developers and business users. The method minimizes the risk of misunderstanding and increases the consistency of the project with real tasks. This method is especially valuable in projects where requirements are complex and may change over time. Using limited contexts allows you to clearly determine the boundaries of responsibility of each module of the system, which simplifies project management.
FDD provides transparency to the development process and makes it easier to manage priorities, as each functionality is clearly defined. This is especially useful for teams working under time constraints. Manageability and predictability of task execution make this method effective for large-scale projects. In addition, the iterative approach of FDD helps to regularly present development results to customers, which increases their involvement in the process.
MDD speeds up the development process through automation, reducing the amount of routine work. Using models makes the code more standardized and makes it easier to check for compliance with architectural requirements. It also reduces the likelihood of human error. Models also provide the opportunity for formal analysis and validation before code generation, which reduces the likelihood of logical errors.
Along with the advantages, the detailed design methods have their drawbacks, which must be taken into account when choosing an approach.
TDD requires significant time to develop tests, especially in the initial stages. This makes the method less suitable for small or fast-growing projects where deadlines are limited. In addition, teams with insufficient experience may face difficulties in implementing TDD. The situation may become especially problematic when developers create tests formally, without proper understanding of their role.
TyDD requires in-depth knowledge of the type system of the programming language used. Limited typing capabilities in some languages may be an barrier to using this method. In addition, even in languages with advanced typing, developers may need additional time to design complex types.
BDD can be time-consuming at the stage of writing behavior scenarios. This process requires additional resources and may not have the expected effect in teams with a low level of interaction. Sometimes it is difficult to achieve a complete understanding of the requirements between all participants, which negates the main advantages of the method.
DDD is difficult to implement due to the need for in-depth study of the domain domain. Small projects or teams without experience with this method may face excessive complexity and costs. The participation of domain experts is often required, as well as careful documentation of limited contexts, which increases project costs.
FDD can lead to fragmentation of the project if the functionality does not integrate well with each other. This method requires careful management of interdependencies. Without proper control and a clear architectural strategy, there is a risk of getting an incomplete system.
MDD requires a highly qualified team and powerful tools. The process of creating models can be a bottleneck, especially in projects with complex requirements. There may also be a problem with the quality of the generated code, which does not always meet the high standards required for industrial solutions.
Detailed design methods are one of those tools that determine the success of a project at all its stages. Their choice requires in-depth analysis, taking into account the specifics of the project and the capabilities of the team. For large projects with high quality requirements, TDD or DDD are often better suited, while BDD and FDD are useful for dynamic and flexible systems. MDD is effective where standardization and automation are important. Successful projects rarely use only one method — combining approaches and adapting them to achieve the best results.