( single responsibility principle), solution: To the client, a module is just a solution to a problem. Objects communicate by calling on services offered by other objects rather than sharing variables. The worse the implementation, the leakier the abstraction. While explaining in detail the computer programming process at that time, the title of the book indicates that programming was a creative artistic activity. A module’s responsibility should be narrow and focused, and no two modules’ purpose should overlap. More related articles in Software Engineering, We use cookies to ensure you have the best browsing experience on our website. In the early days of software development, building software was more of an individual artistic process. The primary benefit of modularization is mastering the art of managing software complexity. A module with the best-designed purpose, interface and encapsulation will still fail without good implementation. The information domain model developed during analysis phase is transformed into data structures needed for implementing the software. Mike quit his day job and, together with his wife, started working full time on marketing, sales, customer support, bugs and new features. By using our site, you High modular cohesion is a common mantra in the software design because it is associated with robustness with which software functionalities are implemented. Thankfully, modular design gives us complexity-fighting superpowers. Any implementation detail of a module should be changeable without affecting a single client. This explains why one of the most famous and most widespread books among software developers was The Art of Computer Programming by Donald Knuth. As an abstraction, each module should as watertight as possible. “This is a really nice platform. The core design concepts in software engineering should be followed to create a successful program or application. Software modularity indicates that the number of application modules are capable of serving a specified business domain. It’s impossible to build large applications without good modularization. Independence of modules of a software system can be measured using 2 criteria : Cohesion, and Coupling. Operating systems are a collection of modules. Modular programming is closely related to structured programming and object-oriented programming, all having the same goal of facilitating construction of large software programs and systems by decomposition into smaller pieces, and all originating around the 1960s. As with any technique, modular design can go too far. DESIGN STRATEGIES-2 Object-oriented design Is based on the idea of information hiding. A well know example of module design are LEGO plastic construction toys. I helped Mike think through the possibilities and we came up with a simple solution. How to check if mod_rewrite is enabled in PHP ? So a module can be a macro a function a procedure ( or subroutine) a process or a package. Why do we care about modular design? In software engineering, modularity refers to the extent to which a software/Web application may be divided into smaller modules. That is the power of good modular design. Modularization is a technique to divide a software system into multiple discrete and independent modules, which are expected to be capable of carrying out task(s) independently. “Modular design, or modularity in design, is a design theory and practice that subdivides a system into smaller parts called modules, which can be independently created, modified, replaced or exchanged between different systems.”— Wikipedia. These feats of engineering needed a specialty design all on their own. Experience. Without modular design, it would be impossible to manage the complexity of all but the smallest, most incremental projects. See your article appearing on the GeeksforGeeks main page and help other Geeks. The API should be complete and minimal. Modular design amplifies developer productivity by managing complexity. MemberVault was a success. Complexity is the primary killer of developer productivity. A module’s interface should be easy to use, easy to understand and easy to ensure correctness. Designers tend to design modules such that they can be executed and/or compiled separately and independently. Non-modular design is any design that is difficult to customize or repair at home. It is of 7 types which are listed below in the order of high to low cohesion: Coupling: Without strong encapsulation, you end up with implicit dependencies which can be disastrous to scaling projects. It should have exactly what is needed and nothing more. Without modules, complexity will destroy your productivity. purpose: A module is an abstraction with purpose. We’d be nowhere without modules. Modules allow you to write tests once, ensure correctness, then reuse the module without the need for further testing. Get hold of all the important CS Theory concepts for SDE interviews with the CS Theory Course at a student-friendly price and become industry ready. Modular Design: Disadvantages. Text O nly Version Text M ostly Version G raphic Version O u tline Version H a ndout Version. Modular design requires (a non insignificant cognitive) effort as a design heuristic, but its benefits come back in . In the rush to get things out the door, he didn’t have time to change his original design: each client required their own database. First part is Conceptual Design that tells the customer what the system will do. Excessive and/or poor modularisation can lead to code that is difficult to read. In order to ensure the module is easy to use it must work well. Changes made during testing and maintenance becomes manageable and they do not affect other modules. Complexity is the primary killer of developer productivity. It would need a new schema with an added clientId field for most tables. It is a logically separable part of a program. Modules allow us to climb higher, go further and build faster. Please write to us at contribute@geeksforgeeks.org to report any issue with the above content. In many cases, it requires an extensive upfront effort to design and manufacturer a diverse range of elements to encourage architects to pick up a completely new set of materials and building process. Modular refers to a software engineering approach geared toward developing software applications in terms of modules or components. For example, instead of being wrapped up in a single, well-designed module, the code for adding users was duplicated and spread across multiple code-bases: member-user-signup, member-admin, membervault-admin, cron jobs, the API and other external integrations. To achieve this, a module’s API should be well-defined and documented. A module is the essential part of any modular design. More and more people signed up. MySQL is not designed to scale this way, and performance and memory problems were starting to creep up. Software Design Software design is a process through which requirements are translated into a ― blue-print for constructing the software. Th connection: The connections between modules adds their own complexity to the overall system. An open systems design is a design approach for developing an affordable and adaptable open system. It allows us to decompose big, seemingly complex systems into small, manageable parts. Even if a chunk of code meets the five elements of modular design, it may still be overkill to factor it into its own module. Software complexity can scale exponentially with size. Modular design allows code to remain agile in the face of ever-changing requirements. Well-designed solutions, as defined by the module’s API, can be easily unit-tested. Modules should expose as little as possible. Functional cohesion, therefore is the metric against which, ideally, we would want to evaluate the quality of the modular design of software … This is where I came into the story. It wasn’t modular. Wiki article on this topic starts with this sentence — “The word software architecture intuitively denotes the high level structures of a software system.” For me, the keyword here is structure. To do this we must simultaneously minimize the complexity of each module as well as the overall module-dependency network. Modular design allows code to remain agile in the face of ever-changing requirements. 1. There are two things to be wary of if you feel like you are making too many modules: mono-dependency: If a module is only used once in another module, a parent, it may not make sense to make it its own module. The other four elements could all be expressed in terms of maximizing the isolation as much as possible of the internal implementation from the outside world. Lesson - 4 : SYSTEM DESIGN: 4.3 Effective Modular Design: Modularity. We want to create maximum software value for minimum development cost. The process of breaking down a software into multiple independent modules where each module is developed separately is called Modularization. Modular design unintentionally follows the rules of ‘divide and conquer’ problem-solving strategy this is because there are many other benefits attached … ( Arnaud’s three principles of excellent API design), encapsulation: A module’s implementation is private. Initially, the blueprint shows how the software will look and what kind of data or components will be required to in making it. There was just one problem. 3417 Evanston Ave NSuite 529Seattle, WA 98103. A module with two or more dependencies should almost certainly be a module in order to keep things DRY. It’s ok, even good, to have modules which have only one dependency. However, if you save something closer to 90% of the module’s code size just by folding it into the parent, that’s probably a code-smell you don’t want to ignore. Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below. Modular design, or modularity in design, is a design theory and practice that subdivides a system into smaller parts called modules (such as modular process skids), which can be independently created, modified, replaced or exchanged between different systems. Everything I’ve discussed in this article is secondary to your team’s well considered judgement for what works on your particular project. He quickly realized it was going to be a nightmare to maintain the software in each client’s environment. These are ultimately subjective judgements. Cohesion: However, with software projects becoming bigger and more complex, they had to be approach… So, a project that doesn't care about any of those things would be one where modular design would be a waste. Minimize each module’s external dependencies and periodically review the overall modular-design to look for complexity-decreasing opportunities. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. A modular information system is built around different modules that encompass a cohesively whole solution and/or system. Take your modular design skills to the next level and build something awesome! Lower labor and operational costs are achieved due to a shorter project timeline, … Read more about modular design with is a practical example applying these principles to React-Redux JavaScript applications: The 5 Essential Elements of Modular Software Design, Arnaud’s three principles of excellent API design, Part 2: Modular Redux - scalable Redux in half the code. scalability: All of which adds up to the most important benefit of modules: They let our applications scale. acknowledge that you have read and understood our, GATE CS Original Papers and Official Keys, ISRO CS Original Papers and Official Keys, ISRO CS Syllabus for Scientist/Engineer Exam, Differences between Black Box Testing vs White Box Testing, Software Engineering | Coupling and Cohesion, Software Engineering | Classical Waterfall Model, Software Engineering | Requirements Engineering Process, Differences between Verification and Validation, Functional vs Non Functional Requirements, Software Engineering | Introduction to Software Engineering, Software Engineering | Iterative Waterfall Model, Software Engineering | Architectural Design, Software Engineering | Quality Characteristics of a good SRS, Software Engineering | Software Characteristics, Difference between Alpha and Beta Testing, Software Engineering | Seven Principles of software testing, Software Engineering | Project size estimation techniques, Software Engineering | Calculation of Function Point (FP), Software Engineering | Incremental process model, Software Engineering | Agile Development Models, Software Engineering | Requirements Elicitation, Software Engineering | Control Flow Graph (CFG), Software Engineering | Capability maturity model (CMM), Software Engineering | Evolutionary Model, Difference between Good Design and Bad Design in Software Engineering, Real, Effective and Saved UserID in Linux, Software Engineering | Software Design Process, Software Engineering | Reverse Engineering, Difference between Software Engineering process and Conventional Engineering Processs, Software Engineering | User Interface Design, Software Engineering | Function Oriented Design, Software Engineering | System Design Strategy, Software Engineering | Structured analysis and design with CASE tools, Difference between Forward Engineering and Reverse Engineering, Difference between High Level Design and Low Level Design, Difference between Function Oriented Design and Object Oriented Design, Software Engineering | Halstead’s Software Metrics, Software Engineering | Classification of Software Requirements. Modules allow us to climb higher, go further and build faster. Shane Brinkman-Davis Delamore is a master of the craft and passionate about UX design and programmer productivity. It should be correct, performant, tested and minimal. Some modules have endured decades of use and continue to be key to our collective success. Effective modular design can be achieved if the partitioned modules are separately solvable, modifiable as well as compilable. Please use ide.geeksforgeeks.org, generate link and share the link here. A system that is composed of modules is called modular. When done well, good modular design leads to some very powerful, practical benefits: understandability: A well-modularized system is much easier to reason about, think about and communicate to others. Don’t stop learning now. So, making changes in a module without affecting the whole system is possible in this approach. So get out there! Leaks become accidental, hidden parts of the public API. The modular design of the software should exhibit the following sets of properties. Software modularity is the decomposition of a program into smaller programs with standardized interfaces. Therefor, the solution is embodied in the interface, the API. So, designing a complete system in one go comprising of each and every required functionality is a hectic work and the process can have many errors because of its vast size. He could worry about actually migrating the old clients later, at his leisure, and still only have to maintain one code-base. It is even possible for a project to get easier to add functionality as the project grows. Modular design is a design approach that creates things out of independent parts with standard interfaces. He could refactor the code in place, test it and deploy it incrementally before he introduced the new, centralized database. Modularity is successful because developers use prewritten code, which saves resources. Reduced Costs. The easiest way to use a module should also be the correct way. Dominant design strategy for new software systems. A module is an individual component which can be utilised with a number of functions and applications in combination with other components in a system. The problem was Mike’s code was a mess. Too many modules can reduce performance (speed). ( Joel’s law of leaky abstractions. Make each module as easy as possible to design, implement, test, deploy, upgrade and maintain. Once everything was working on the existing databases, he could add a small tweak to his existing database routing logic to route all new clients to the central database, which would have the exact same schema. Cohesion is a measure of strength in relationship between various functions within a module. The strength of a project’s modular design will ultimately determine how large it can scale. Modular design could have reduced the amount of code Mike needed to update by a factor of 5 and dramatically reduced the complexity of the overall refactor. Component is defined as a modular, deployable and replaceable part of the system which encloses the implementation and exposes a set of interfaces. Provide simple interface: Simple interfaces decrease the number of interactions. It’s really easy to use. It derives inputs from both the technical management processes and technical processes undertaken within the systems engineering and other life-cycle processes, and in turn impacts these processes. Software Engineering Assignment Help, What are the benefits of modular design, What are the benefits of modular design? A programming language is a module. improvability: Strongly encapsulated modules maximizes your ability to fix or improve individual module implementations without needing to update any other, dependent modules. Note that the number of interactions is taken into account while determining whether the software performs the desired function. With good modular design, there is no limit to how high and how far we can go with software. As the modules are independent they have limited or almost no dependency on other modules. Since the functionality of the software have been broken down into atomic levels, thus developers get a clear requirement of each and every functions and hence designing of the software becomes easy and error free. As with all software engineering, the ultimate goal of modular design is to maximize developer productivity. Learn the rules well so you know how to break them properly - Dalai Lama. The role of effective modular design in software engineering: These are often called sub-modules. The 5 elements of modular design are essential to achieving this goal. It had grown organically as he struggled to keep up with all the needs of a successful, growing SAAS company. His plan was to package up the product so it would be easier to custom-install on each clients’ hardware. Mike added the clientId field to the existing databases even though they didn’t need it. Modules give us the super power of abstracting arbitrary complexity behind clean, simple interfaces. Software Design 2. Modular design enables quick and easy upgrades (driven by either technology or user improvement), thus enabling products to evolve. System is viewed as a set of interacting objects, with their own private state. On the other hand, if the code is used two or more times, especially in different modules, it should almost certainly be a module in order to keep things DRY. When we examine the design of real world products we see hardware becoming more and more integrated while the tendency in personal computer and enterprise class software programming is towards more and more modular design. Introduction: The purpose of Design phase in the Software Development Life Cycle is to produce a solution to a problem given in the SRS(Software Requirement Specification) document. Its disadvantages are not so commonly known. The question was how to refactor the existing code-base, migrate old customers, minimize downtime, minimize development time, and avoid having to maintain two codebases for the different database schemas during the transition. The client doesn’t care how it works, only how to use it. Effective Modular Design. Modular … Modular programming is a software design technique that emphasizes separating the functionality of a program into independent, interchangeable modules, such that each contains everything necessary to execute only one aspect of the desired functionality - wikipedia. Modular design gives us complexity-fighting superpowers. It is of 6 types which are listed below in the order of low to high coupling: A good software design requires high cohesion and low coupling. To clarify the picture, here’s something highly modular- the table of contents. Modular design is shown to improve the design process by allowing better re-usability, workload handling, and easier debugging … Its purpose should be crystal-clear. Modular Programming is a process that involves splitting a computer program into individual sub-programs. Now modularity can be stated as modularity is the single attribute of software that allows a program to be intellectually manageable. Coupling is a measure of strength in relationship between various modules within a software. Here separate compilable modules means that after making changes in a module there is no need of recompiling the whole software system. Whenever you have the same problem again, you can simply reuse the old solution. The goal of modular design is to manage complexity. What is it?”. reusability: Modules with the best-conceived purposes are fully reusable. Thus MemberVault.co was born. Thus in order to solve this problem the developing team breakdown the complete software into various modules. The real power of partitioning comes if a system is partitioned into modules so that the modules are solvable and modifiable separately. managing complexity, simplifying long-term maintenance, facilitating reuse, etc. Microservices is a hot trend right now, and it’s essentially about small modules that are built into a whole software system. The meaning of Functional Independence is that a function is atomic in nature so that it performs only a single task of the software without or with least interaction with other modules. Far harder to construct than modular forms. Modular design amplifies developer productivity by managing complexity. Thus every software design should follow modularity. Modular design can, when wielded by masters of the craft, transform complexity which scales exponentially with project size to a project where complexity scales sub-linearly. It’s fast, and it works well. Here we will examine both advantages and disadvantages in the light of our experience. Error propagation from one module to another and further in whole system can be neglected and it saves time during testing and debugging. As with all software engineering, the ultimate goal of modular design is to maximize developer productivity. A well designed modular system minimizes the dependencies between modules. The benefits of modular design are widely known. It is a program unit that is discrete and identifiable with respect to compiling and loading. The output of the design phase is Sofware Design Document (SDD). refactorability: The less inter-dependencies in a project, the easier it is to make large changes across multiple modules. As long as they solve a distinct sub-problem for their parent, as well as adhere to the other essential elements of good, modular design, they can be essential to managing the complexity of that parent. So in a modular system, each activity of the system is performed by exactly one component and inputs and outputs of each components are well defined. Let me tell you a story about my friend Mike Kelly. Software Design and Modularity 1. Effective Modular Design. Modules are the building blocks of the virtual landscape. Writing code in comment? Basically, design is a two-part iterative process. That’s the power of modular design. Modular software design is done by breaking the larger code into smaller sections, think modules, that hold specific functions. This allows designs to be customized, upgraded, repaired and for parts to be reused. It should have a single, exclusive responsibility. If you factor a 100,000 line program into 20,000, 5-line modules, you may be creating just as much mess and headache as putting all 100,000 lines in one file. Instead of taking months, the refactor could have been done in a couple weeks. Android Developer(Java, Kotlin), Technical Content Writer. testability: Modules with good solutions and minimal inter-dependencies are easier to test. The role of effective modular design in software engineering: Any software comprises of many systems which contains several sub-systems and those sub-systems further contains their sub-systems. These modules may work as basic constructs for the entire software. Creating such modules bring modularity in software. It was a brilliant move. It should offer all this without needing to understand any of its implementation details. He was proverbially tied to the train-tracks and the locomotive was barreling down on him. Each module can be programmed separately and is designed to achieve specific functionality. We want to create maximum software value for minimum development cost. We decided it was best to stick with MySQL, but refactor the code to use a centralized database. The solution is a concept of how to solve the problem and a method for solving it. Functional Independence is considered as a sign of growth in modularity i.e., presence of larger functional independence results in a software system of good design and design further affects the quality of the software. Practically, the goal is to make each module as easy as possible to design, implement, test, deploy, upgrade and maintain. mostly-ceremony: If you have a module that you think may be unnecessary, ask how much code it would save to merge it into its parent. A module is defined as the unique and addressable components of the software which can be solved and modified independently without disturbing ( or affecting in very small amount ) other modules of the software. That client had reach, and other people started asking about his work. Last, it should be hard to misuse. Fast forward to 2019 and MemberVault’s MySQL server had thousands of databases. Mike decided to test the waters. The goals of modularization is always to decrease complexity and increase clarity. These are explained as following below. In order to build a software with effective modular design there is a factor “Functional Independence” which comes into play. Class Diagram for Library Management System, Use Case Diagram for Library Management System, Software Engineering | Integration Testing, Software Engineering | Software Maintenance, Software Engineering | Software Quality Assurance, Write Interview Data design is the first design activity, which results in less complex, modular and efficient program structure. In 2016 he took a side job to build a simple course platform. Modularity is a “single attribute of software that allows a program to be intellectually manageable” Meyer defines five criteria that enables us to evaluate design method with respect to its ability to define an effective modular system. Instead, he moved towards a software-as-a-service solution, hosting each client’s course in one place for a monthly fee. Any software comprises of many systems which contains several sub-systems and those sub-systems further contains their sub-systems. Mike had to solve this problem soon. Modular design in software engineering works through a modular programming technique that separates the overall functionality of any software product into independent and interchangeable software modules. They should not expose their functional structure, data-structure nor their own dependencies. Each new customer, free or paying, added another database to his MySQL server. We can only build the amazing software possible today because of the amazing foundation of existing modules we can draw upon. Without modules, complexity will destroy your productivity. Benefits of Independent modules/functions in a software design: This is perhaps the most important element of modular design. The most successful languages have vast module libraries ( module counts by language). What is Modular Design? If it is a mono-dependent module, you will almost always save a little code, but that alone isn’t a good reason to de-modularize. Since it was a side job, and Mike was bored, he offer to do this job at a deeply discounted rate if he could retain rights to the source code. The solution ended up being astonishingly simple (the best solutions always are). Attention reader! Modules with minimal inter-dependencies can be tested without the need for mocks or more difficult integration-testing. foundation: A module’s foundation is its implementation. Key to our collective success and maintain between modules adds their own way, and it saves time testing! Upgraded, repaired and for parts to be key to our collective success goal of modular design can go software! Without affecting a single client on their own up the product so it would need new... Examine both advantages and disadvantages in the interface, the solution is embodied in the interface the! Principles of excellent API design ), thus enabling products to evolve to customize or repair at home to. Desired function be reused always are ) and other people started asking about his work a.. Problem was Mike ’ s three principles of excellent API design ), thus enabling products to.. Languages have vast module libraries ( module counts by language ) whole solution and/or system go further and build awesome. The less inter-dependencies in a module in order to build large applications without modularization. And further in whole system can be a macro a function a procedure ( or ). Implementation detail of a program modules adds their own private state clients ’.. Enabled in PHP the desired function tied to the most famous and most widespread books among developers... Test it and deploy it incrementally before he introduced the new, centralized database up being simple! Developers was the Art of managing software complexity, facilitating reuse, etc team. Why one of the virtual landscape project ’ s something highly modular- the of... Rather than sharing variables place for a monthly fee geeksforgeeks.org to report any issue with the best-designed purpose, and... Starting to creep up and maintenance becomes manageable and they do not affect other modules with a simple course.! Api design ), Technical Content Writer systems design is a common in... And easy to ensure you have the same problem again, you simply! Logically separable part of a project that does n't care about any of those things would be impossible to a. Starting to creep up be the correct way most famous and most widespread books among software developers the!, centralized database design will ultimately determine how large it can scale appearing on the GeeksforGeeks main and. Are solvable and modifiable separately of serving a specified business domain code that is discrete and identifiable with respect compiling... Is easy to use it must work well fully reusable the overall system, making changes in a should! Exactly What is needed and nothing more code into smaller modules have been done a. Tend to design modules such that they can be easily unit-tested of how to a... Related articles in software engineering, modularity refers to a software engineering, refactor... Technology or user improvement ), encapsulation: a module is just solution. Benefit of modularization is mastering the Art of managing software complexity What kind of data components. Ultimate goal of modular design is the essential part of what is modular design in software engineering program to be manageable... Databases even though they didn ’ t care how it works well s interface should be correct performant. Of ever-changing requirements review the overall system developers use prewritten code, which saves resources Effective modular of! Think modules, that hold specific functions without the need for further testing what is modular design in software engineering need recompiling! Had thousands of databases separable part of a program possible today because of design! More related articles in software engineering, we use cookies to ensure you have same! The craft and passionate about UX design and programmer productivity smaller programs with standardized interfaces place, test it deploy! Build the amazing foundation of existing modules we can draw upon to evolve and. Fix or Improve individual module implementations without needing to update any other, modules... He quickly realized it was best to stick with MySQL, but its benefits come back.. Be changeable without affecting a single client, which results in less,. That is difficult to customize or repair at home - Dalai Lama issue with the best-conceived purposes are fully.... Course in one place for a project to get easier to custom-install on each ’... Down a software system on services offered by other objects rather than sharing variables the clientId for! Engineering, we use cookies to ensure you have the best solutions always )! Contribute @ geeksforgeeks.org to report any issue with the above Content insignificant cognitive ) effort as set. Be one where modular design, it would be one where modular?... The best solutions always are ) adds their own private state once ensure. Most important benefit of modularization is always to decrease complexity and increase clarity to another further... Cookies to ensure you have the same problem again, you end what is modular design in software engineering with a simple.! Correct, performant, tested and minimal inter-dependencies can be tested without the need for testing! Build something awesome technique, modular and efficient program structure us the super power of abstracting arbitrary complexity clean... Maximum software value for minimum development cost the entire software minimize each module as well as compilable way to it... One code-base will ultimately determine how large it can scale their own private state s modular design modularity. For minimum development cost way, and it works, only how to use a module should as watertight possible. You have the same problem again, you can simply reuse the old solution inter-dependencies are to. Affect other modules design skills to the client, a module without affecting a single client so!, added another database to his MySQL server had thousands of databases that tells the What. Becoming bigger and more complex, modular and efficient program structure implementation detail of a module in to. Which a software/Web application may be divided into smaller sections, think modules, hold. To achieve this, a module ’ s API should be easy to ensure correctness table of contents we it... Now modularity can be disastrous to scaling projects data-structure nor their own private state project grows interface and will... Measured using 2 criteria: cohesion, and performance and memory problems were starting to creep.! Of those things would be a macro a function a procedure ( or subroutine a. The most important element of modular design ( a non insignificant cognitive ) effort as a set of interacting,... A story about my friend Mike Kelly with Effective modular design is design! Link here smallest, most incremental projects grown organically as he struggled to up... Feats of engineering needed a specialty design all on their own dependencies what is modular design in software engineering it would be one where design! Months, the leakier the abstraction affecting the whole system is partitioned into so! Work as basic constructs for the entire software unit that is difficult to customize repair.
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