Software maintenance is not about fixing wear and tear. One of these two systems is fast and user-friendly, and its source code is easy to modify. The change is nicely isolated, and tests confirm that it works as intended. Different languages implement comments in different ways. But no matter the domain, the characteristics defined in ISO 25010 still apply. Having irrelevant artifacts such as TODOs and dead code in your codebase makes it more difficult for new team members to become productive. And that is just the difference between above-average and below-average maintainability. However, it turns out it is full of bugs!”. This allows the programmer to easily see which code falls within the selection or iteration, and where it ends. Sync all your devices and never lose your place. Consequently, a system may have above-average maintainability and still suffer from problems regarding functional suitability, performance, reliability, and more. The Jenkins codebase is not perfect. But what is “easy to maintain” and what is “hard to maintain”? Being a software developer can also be a painstaking job. The purpose of maintainability. Join the O'Reilly online learning platform. These systems had such a low degree of modification efficiency and effectiveness that the system owner could not afford to maintain it. Collectively, they affect both the utility and the life-cycle costs of a product or system. 1. Read the first chapter from Building Maintainable Software, Java Edition, to learn exactly what maintainability means and how it has an impact on business. programming language, organization, type of system, type of project; the skill and knowledge of the people involved must also be considered then drawing conclusions.Many researchers have tried to quantify maintainability in different types of measures[1,2,10,23,24,36] , of which the most noticeable probably is the Maintainability Index, MI Maintenance efforts are reduced when issue resolution and enhancements can be performed quickly and easily. Our principle is the very opposite: maintainability requires following simple guidelines that are not sophisticated at all. We take a different approach. Above-average maintainability means nothing more than that the modifications needed to reduce the number of bugs can be made at a high degree of efficiency and effectiveness. SIG divides the systems in the benchmark by star rating, ranging from 1 star (hardest to maintain) to 5 stars (easiest to maintain). To demonstrate the maintainability improvement, we refactored a COTS-based system known as OpenBravoPOS using AspectJ and compared its maintainability … Programmers should choose a variable name that reflects the purpose of the variable and the. Depending on performance, portability, and maintainability needs, different code generation techniques may be used [Wang 1987]. “My team repeatedly has been able to fix bugs in this system. The average maintainability of all Java systems in our benchmark is itself average, and the same holds for C#. The time it takes to resolve issues and make an enhancement is on the order of days or weeks. In practice, resolving all violations is neither necessary nor profitable. Aspect-oriented programming (AOP) is a relatively new approach that emphasizes dealing with crosscutting concerns. Remember that you are writing code not just for yourself, but also for less-experienced developers that come after you. Modules (classes) that are loosely coupled are easier to modify and lead to a more modular system. In the following chapters, each guideline is presented and discussed. - better choice. More often than not, such systems are written off before they ever see a 1.0 release. can be part of the same development process. Maintainability In the preceding sections, we have seen a number of features that C++ offers, and the viability of using them on a resource-limited platform. Of course, there are differences between these domains. Maintainability is not an afterthought, but should be addressed from the very beginning of a development project. Sometimes, you can quickly identify the lines of code to change. The other system is slow and difficult to use, and its source code is nearly impossible to understand, let alone modify. Units (methods and constructors) with fewer parameters are easier to test and reuse. Maintainability: | In |engineering|, |maintainability| is the ease with which a product can be maintain... World Heritage Encyclopedia, the aggregation of the largest online encyclopedias available, and the most definitive collection ever assembled. We believe that the guidelines presented in this book are applicable to all forms of software development: embedded software, games, scientific software, software components such as compilers and database engines, and administrative software. Therefore, it is at least as maintainable as any other system.”. programming has been widely acclaimed as the technology that will support the creation of reusable software, particularly because of the "inheritance” facility. While a program will run with such names, it makes understanding the purpose of the variable much more difficult. Software Maintainability: What it Means to Build Maintainable Software. After the next section, which discusses common misunderstandings about maintainability, we explain how quality profiles are used to measure the maintainability of a system. The star ratings serve as a predictor for actual system maintainability. However, the guidelines described in this book are not specific to Java. for count = 1 to 10 Our dataset contains Java systems that are among the most maintainable, but also, that are among the least maintainable. © 2020, O’Reilly Media, Inc. All trademarks and registered trademarks appearing on oreilly.com are the property of their respective owners. The value to be inputted will be a number. This book discusses these properties and presents 10 guidelines to help you write source code that is easy to modify. A programmer may decide to return to a program they wrote some time before in order to add an extra feature. In the current chapter, we introduce the principles behind these guidelines: Maintainability benefits most from adhering to simple guidelines. Software is not physical, and therefore it does not degrade by itself the way physical things do. Programming and debugging. Duplication is also a source of regression bugs. This includes using: Comments are lines in programs that provide information about what the different parts of the program do. Object Oriented Programming (OOP) is a Programming Paradigm which is based on the concept of … Programming languages should allow programs to be easily modifiable. For example, highly maintainable code is more stable than unmaintainable code: changes in a highly maintainable system have fewer unexpected side effects than changes in an entangled system that is hard to analyze and test. “You said the system has above-average maintainability. Software maintainability requires more developer effort than any other phase of the development life cycle. Ability to readily maintain Performance and scalability in the event of changes. The three approaches are interpreted code, high-level programming language source code, and native machine code. Maintainability is an enabler for other quality characteristics. This book presents 10 guidelines that, if followed, lead to code that is highly maintainable. Some violations are worse than others. “Our system uses a state-of-the-art programming language. It has severe unit size violations: 6% of the codebase is in very long units (more than 60 lines of code). It signifies different degrees of being able to maintain a system. In the interpreted … This distinction is important. After that, we discuss why maintainability is important. The maintainability of software depends on a few different factors. Maintainability. Being a software developer is great. Finally, the third chart in Figure 1-1 shows the unit size cutoff points for 4 stars. OBJECT-ORIENTED SYSTEM . What if a fragment of source code violates one or more of these guidelines? In a sidebar at the end of each guideline chapter, we present the quality profile categories for that guideline as we use them at SIG to rate maintainability. again = input("Enter y to go again") A programming team will perform four types of maintenance on new deployments or enhancements: corrective, adaptive, perfective, and preventative. Yet, in R, it is a good idea to keep units short and simple. So whenever a compromise has to be made between performance and maintainability, the former wins over the latter. The international standard ISO/IEC 25010:2011 (which we simply call ISO 25010 in this book1) breaks down software quality into eight characteristics: maintainability, functional suitability, performance efficiency, compatibility, usability, reliability, security, and portability. Programs must run correctly or they are of little value. Even though both systems have the same functionality, their quality clearly differs. Read the first chapter from Building Maintainable Software, Java Edition, to learn exactly what maintainability means and how it has an impact on business. That is why all developers must be disciplined and follow the guidelines to achieve a system that is maintainable overall. The ease or difficulty with which a software system can be modified is known as its maintainability. At some point, the additional gains in maintainability become smaller and smaller, while the costs become higher and higher. Therefore, it makes maintenance less efficient. This maintenance acts as medicine to prevent the problems. Four types of software maintenance can be distinguished: Bugs are discovered and have to be fixed (this is called corrective maintenance). Some programming languages, such as Scala and Perl, aim to be as expressive as possible, giving you maximum flexibility in how you write your code. The data we have at SIG does not indicate that the technology (programming language) chosen for a system is the dominant determining factor of maintainability. Embedded software has to operate in an environment where performance predictability is essential and resources are constrained. Request a Live Demo. Some programming languages, such as Python, indent such code automatically. Every individual contribution counts. If maintainability is so important, how can you improve maintainability of the code that you write? Restructuring the data and code of the software are implemented in preventive maintenance. Difficult-to-maintain source code is a big problem in software development today, leading to costly delays and defects. Even though ISO 25010 does not describe how to measure software quality, that does not mean you cannot measure it. All modifications require finding a specific piece of source code and analyzing it, understanding its inner logic and its position in the business process that the system facilitates, analyzing dependencies between different pieces of code and testing them, and pushing them through the development pipeline. Therefore, your individual contribution is of great importance to the whole. But with Java 8 it was the big change in paradigm for Java developers. print("Hey!") A factor of two is a significant quantity in the practice of enterprise systems. In Python, for example, a comment begins with a hash symbol, and is coloured red: #ensures the input is restricted to a y or an n. Many programmers choose meaningless variable names such as x or y. More generally speaking, optimizing a software system requires modifications to its source code, whether for performance, functional suitability, security, or any other of the seven nonmaintainability characteristics defined by ISO 25010. A very simple and short difference between Agility and Maintainability in programming practices can be as below : . Read about our approach to external linking. The origins of contemporary reliability engineering can be traced to World War II. A very simple and short difference between Agility and Maintainability in programming practices can be as below : . Following the guidelines in this book not only results in more maintainable code, but also sets the right example for your fellow developers. Additionally, another programmer may wish to modify the program in order to improve it or debug an error. Manual tests do not scale. Posts about Maintainability written by Suresh Peram. Take O’Reilly online learning with you and learn anywhere, anytime on your phone and tablet. So why is maintainability so important that it warrants its own, dedicated book? While the scientists are hopefully working on that one, there is also something we can do today. Preventive maintenance helps the software to become more scalable, stable, understandable, maintainable. III. Code within selections or iterations should be indented. At SIG we have seen newly built systems for which the maintainability was so low that it was no longer possible to effectively modify them—even before the systems went into production. Gone are the days when knowing a programming language such as C, C++, C# or Java defined what a programmer’s capabilities were. In general, it must be easy to understand the software ... Secondly, there is pair programming, where instead of reviewing the code after it's developed, the code is reviewed by a second developer as it is written. should be indented. Performance (how slow or fast a system produces its output) is another. Automated tests (that is, tests that can be executed without manual intervention) enable near-instantaneous feedback on the effectiveness of modifications. To keep the metrics simple but also practical, we determine the quality of a complete codebase not by the code’s number of violations but by its quality profiles. Clearly, a complex system is easier to maintain by an expert than by a less experienced developer. In any case, in a more maintainable system, these modifications are easier to make, allowing you to implement quality optimizations faster and more effectively. Maintainability (how easily a system can be modified) is one characteristic of software quality. Perfective maintenance maximizes the maintainabilityor understanding of the software system. We are fully aware that in practice, almost always there will be exceptions to the guideline. In the following chapters, we will present the guidelines one by one, but here we list all 10 guidelines together to give you a quick overview. Verify if the data processing split up into subtransactions? Sometimes they involve more invasive restructuring. The hidden assumption is that all violations should be resolved. It is not the difference between fixing 5 bugs or 10 in an hour; it is the difference between being the first one to the market with a new product, or seeing your competitor months ahead of you. Get a free trial today and find answers on the fly, or master something new and useful. For consistency, we are using Java code snippets throughout the book. We know now that maintainability is a quality characteristic on a scale. maintainability. There are two angles to this question: Maintainability, or lack thereof, has significant business impact. Design for Maintainability Basic Principles Maintainability is the degree to which a product allows safe, quick and easy replacement of its component parts. These are challenging and rewarding endeavors. The quality profile tells us that the Jenkins codebase has 64% of its code in methods that are no longer than 15 lines of code (compliant with the guideline). Imagine two different software systems that have exactly the same functionality. The benchmark is recalibrated yearly. Ability to readily maintain Performance and scalability in the event of changes. Both angles are discussed in the next two sections. If software metrics for a system score below average, it is harder than average to maintain. “Maintain-Ability” is literally the ability to maintain. 1Full title: International Standard ISO/IEC 25010. These differing perspectives on maintainability have always been a cause of immense grief to IT projects. Object-oriented systems are Trapidly replacing procedure- oriented systems as the latter are less maintainable and non- reusable. Top-level components of a system that are more loosely coupled are easier to modify and lead to a more modular system. Additionally, another programmer may wish to modify the program in order to improve it or, . This sets the stage to introduce the main topic of this book: how to build software that is maintainable from the start. These guidelines guarantee sufficient maintainability, not perfect maintainability (whatever that may be). In this section, we discuss some misunderstandings about maintainability that are encountered in practice. At other times, the only solution is to use a hack that creates more problems than it solves. A well-balanced architecture, with not too many and not too few components, of uniform size, is the most modular and enables easy modification through separation of concerns. This is what software maintenance is about. This shows us that it is possible to make very maintainable systems in Java (and in C#), but using either of these languages does not guarantee a system’s maintainability. People may think that maintainability requires a “silver bullet”: one technology or principle that solves maintainability once and for all, automagically. The maintainability index is calculated with certain formulae from lines-of-code measures, McCabe measures and Halstead complexity measures. Ways are identified to increase quality or prevent future bugs from occurring (this is called preventive maintenance). Development took so long that the business environment (and therefore, user requirements) had already changed. The efficiency and effectiveness with which issues can be resolved and enhancements can be realized is therefore important for stakeholders. symfony2,svn,shared,maintainability,bundles. Software is not static. Jackson Structured Programming) were driven by required functionality and the flow of data through the system, but the current insight is that the architecture of a software system is more closely related to its quality attributes such as fault-tolerance, backward compatibility, extensibility, reliability, maintainability, availability, security, usability, and other such –ilities Specifically, for each guideline, we present the cutoff points and the maximum percentage of code in each category for a rating of 4 stars or higher (top 35% of the benchmark). Fast enhancements mean shorter time-to-market of new products and services supported by the system. You can tell that Jenkins complies to the unit size guideline for 4 stars (although not for 5 stars), since the percentages of code in each category are lower than the 4-star cutoffs. Therefore, it has been proven that it is maintainable.”. Units with fewer decision points are easier to analyze and test. A lack of maintainability will be evident as high product maintenance costs, long out-of service times, and possible until again !="y", Translators and facilities of languages - OCR, Computational thinking, algorithms and programming, Home Economics: Food and Nutrition (CCEA). When someone gives you a problem and requirements, you are able to come up with a solution and translate that solution into a language that a computer understands. Given the ISO 25010 definition of maintainability, one could say that a software system is never perfectly maintainable nor perfectly unmaintainable. Figure 1-1 shows three examples of unit size quality profiles (print readers can view full-color figures for this and the other quality profiles that follow in our repository for this book). During most of this time, there is a continuous stream of issues that need to be resolved (corrective and adaptive maintenance) and enhancement requests that have to be met (perfective maintenance). exibility, and maintainability of a large class of programs. First Edition, 2011-03-01. Agility: Ability to quickly respond to changing business needs, and. SIG has collected empirical evidence that issue resolution and enhancements are twice as fast in systems with 4 stars than in systems with 2 stars. A programmer may decide to return to a program they wrote some time before in order to add an extra feature. Apparently, there are other factors that determine maintainability. Programmers should choose a variable name that reflects the purpose of the variable and the data it is intended to hold: height - better choice. The profile also shows that 18% of all the code in the codebase is in methods between 16 and 30 lines of code, and 12% is in methods between 31 and 60 lines of code. When a system has high maintainability, it is easier to make improvements in the other quality areas, such as fixing a security bug. Duplication of source code should be avoided at all times, since changes will need to be made in each copy. Users of the system (and/or other stakeholders) have new or changed requirements (this is called perfective maintenance). KEYWORDS: Object Oriented programming Language, Inheritance, Control, Reusability and Maintainability Introduction. As you have learned, maintainability is only one of the eight characteristics of software product quality identified in ISO 25010. The second chart in Figure 1-1 shows the quality profile of a 2-star system. To a developer, maintainable code simply means “code that is easy to modify or extend”. Functional Programming is nothing new to the JVM. This all-or-nothing view on violations may lead developers to ignore the violations altogether. Yet most software systems are modified all the time after they have been delivered. Maintainability Testing Checklist: Verifying the development standards such as structured programming, standards for database approach, recognizable nomenclature and standards for the user interfaces. Careful planning and testing of a program are essential, as is writing maintainable code. Many types of tooling for software quality assume that each and every violation is bad. We understand that it is hard to see whether an individual “violation” of the guidelines in this book influences the overall maintainability of the system. do Load bundles from a separate SVN repository. The purpose of maintainability is to ensure that, over time, a program can be easily maintained. Source code that complies with these guidelines can still be made more maintainable. Learn how switching from imperative to… Maintainability needs to be addressed from the very start of a development project. When the number of developers stays the same, with efficient maintenance they have more time for other tasks, such as building new functionality. Sign in, choose your GCSE subjects and see content that's tailored for you. For both issue resolution and enhancements, it holds that if they are slow and troublesome, deadlines may not be met or the system may become unusable. In both situations, the understanding of the program, how it works and the purpose of the code will be made easier if the program is written in a maintainable style. This book focuses exclusively on maintainability. In these systems, there are still violations to the guidelines, but much fewer than in systems rated below. ... Maintainability - it is easier to fix bugs and flaws because the code is easier for others to read and understand. 1 Introduction A traditional argument against abstraction-based programming has been loss of performance. According to the ISO 25010 definitions, a system can be highly maintainable and still be lacking in other quality characteristics. In this paper, we explore the importance of reusability and maintainability in object oriented language. Compare this chart to the first one. In not available, we present how we measure software quality at the Software Improvement Group (SIG) in accordance with ISO 25010. This allows the programmer to easily see which code falls within the selection or iteration, and where it ends. It is meant to address the difficulties with procedural programming with its aim to try and increase the flexibility and maintainability of programs. Thus, in the benchmark the systems that are among the top 5% are rated 5 stars. We will discuss these techniques in the following few pages, using a worked example to demonstrate. The more a software system complies with the guidelines, the more maintainable it is. Designing and coding for maintainability will stop exponential growth. A big advantage of using C++ is the reduction in code size you can accomplish through the use of templates, along with the organization and modularization of a code base using classes, namespaces, and the like. I can’t work like this!! Verify if the input, the processing and the output have been implemented separately The software engineering literature proposes many models and metrics to predict the maintainability of a software project statically. Language expressiveness versus code maintainability. Who wrote this piece of code?? There are several standard techniques to help with maintainability that every programmer should follow, regardless of which programming language they use to write their code. A Software Maintainability Attributes Model - Free download as PDF File (.pdf), Text File (.txt) or read online for free. For instance, in not available, we tell you to never write methods that have more than 15 lines of code. By using quality profiles, we can distinguish moderate violations (for example, a method with 20 lines of code) from severe violations (for example, a method with 200 lines of code). A large system is difficult to maintain, because more code needs to be analyzed, changed, and tested. Also, maintenance productivity per line of code is lower in a large system than in a small system. ASSESSING MAINTAINABILITY IN SOFTWARE ARCHITECTURES THE ELUSIVE SOCIO-TECHNICAL DIMENSIONS OF MAINTAINABILITY Tese de doutoramento do Programa de Doutoramento em Ciências e Tecnologias da Informação orientada pelo Professor Doutor Mário Alberto da Costa Zenha-Rela e apresentada ao Departamento de Engenharia Informática It can be defined as the ease with which a software system or component can be modified to be corrected, improved, or adapted to its environment. The system has to be adapted to changes in the environment in which it operates—for example, upgrades of the operating system or technologies (this is called adaptive maintenance). Languages and Maintainability. If you regularly have to change source code written by others (or even by yourself), you know that it can be either really easy or really difficult. They serve no other purpose, and are not executed when the program is run - the program simply ignores them and moves on to the next line of code. Maintainability refers to the capability of the equipment of product to retain or restore relevant functions after being maintained as per specified processes or methods under given conditions and in a given time. The value to be inputted will be a number. More modifications were needed, which introduced yet more bugs. We advise you to read this book starting with not available and work your way through sequentially. The maintainability of a software system is determined by properties of its source code. According to its definition in ISO 25010, source code maintainability is not a binary quantity. The distribution of these star ratings among systems from 1 to 5 stars is 5%-30%-30%-30%-5%. This avoids the “broken windows effect” in which other developers temporarily relax their discipline and take shortcuts. SIG has collected empirical evidence that issue resolution and enhancements are twice as fast in systems with above-average maintainability than in systems with below-average maintainability. In fact, SIG has benchmarked systems in over a hundred programming languages based on the guidelines and metrics in this book. Exercise your consumer rights by contacting us at donotsell@oreilly.com. again.lower In this chapter, we explain what we mean when we speak about maintainability. Our tips from experts and exam survivors will help you through. What was the norm in software engineering a few years back, may be subpar now. Modifications introduced more bugs than they solved. Another reason why maintainability is a special aspect of software quality is that it acts as an enabler for other quality characteristics. As the industry learns to code more efficiently (e.g., with the help of new technologies), the average for metrics tends to improve over time. Main features that languages can provide to support modification are shown diagrammatically in fig 6.16, and discussed below one by one. Documentation updating or code optimizing are involved in preventive maintenance. Difficult-to-maintain source code is a big problem in software development today, leading to costly delays and defects. Introduction to Languages and Maintainability. Maintainability is different there.”. If you build a valuable product that works perfectly but is difficult to modify and adapt to new requirements, it … is to ensure that, over time, a program. The guidelines in this book present metric thresholds as an absolute rule. Terms of service • Privacy policy • Editorial independence, Get unlimited access to books, videos, and. The discipline’s first concerns were electronic and mechanical components (Ebeling, 2010). The systems in the benchmark are ranked based on their metric quality profiles. Some programming languages, such as Python, indent such code automatically. This feature implies a degree of difficulty of the maintenance provided to the device or product. Systems and Software Engineering — Systems and software Quality Requirements and Evaluation (SQuaRE) — System and Software Quality Models. By benchmarking, at SIG we let the metrics in the software industry answer this question. Use Composer Put every bundle that needs to be shared between multiple projects in it's own repository, and use Composer to manage your dependencies (which are … Sometimes they are small, local modifications. At the end of this introduction we discuss common misunderstandings about maintainability and introduce the principles behind the 10 guidelines presented in this book. In software development, the maintenance phase of a software system often spans 10 years or more. A quality profile divides metrics into distinct categories, ranging from fully compliant code to severe violations. next count Shorter units (that is, methods and constructors) are easier to analyze, test, and reuse. The first chart in Figure 1-1 is a quality profile for unit size based on the source code of Jenkins version 1.625, a popular open source continuous integration server. Instead, maintainability is the degree to which changes can be made efficiently and effectively. While a program will run with such names, it makes understanding the purpose of the variable much more difficult. In practice, we at SIG have encountered systems that can be considered unmaintainable. For example, scientific software often uses a special-purpose programming language, such as R, for statistical analysis. So the right question to ask is not whether changes (such as bug fixes) have been made, but rather, how much effort did fixing the bug take (efficiency), and was the bug fixed correctly (effectiveness)? The handling of concurrency issues has been collected into a small new library, YAPL. Doing maintenance on this system is a very painstaking job. Agility: Ability to quickly respond to changing business needs, and. can be easily maintained. How different programming languages lead to different software maintenance challenges - 13 August 2018 #code #maintenance Crystal Kwok. The SeaLights Software Metrics Guide for Better and Faster CI/CD. Software maintainability is a crucial property of software projects. The measurement and track of maintainability are intended to help reduce or reverse a system's tendency toward "code entropy" or degraded integrity, and to indicate when it becomes cheaper and/or less risky to rewrite the code than it is to change it. Reliability, maintainability, and availability (RAM) are three system attributes that are of great interest to systems engineers, logisticians, and users. This thought helps you to simplify the solution you are programming. Given the same input, both compute exactly the same output. Notice that over one-third of the codebase is in units that are over 60 lines of code. Even though the 15% change seems to be constant, that doesn’t necessarily mean that every system gets 15% bigger every year. If efficient maintenance leads to less maintenance personnel (developers), it also lowers maintenance costs. “My team makes embedded software for the car industry. Setting the right example is not necessarily about being the most skilled engineer, but more about retaining discipline during development. The benchmark thus reflects the state of the art in software engineering. It is embodied in the design of the product.
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