Pair programming also means both participants won't be distracted by Facebook or e-mail, and can learn handy hints and tips off each other to improve their skills! Answering the following questions will help you judge the maintainability of your software: Now ask the questions again but, this time, adopt the perspective of someone else in your team and someone who is completely new to your software. Website accessibility. You may be developing open-source software with the intent that it will live on after your project completes. This has to be supported by analytical investigations (Chaps. These actions all incur technical debt and - just like financial debt - it's a debt that gathers interest over time. Maintainability testing shall use a model of the maintainability requirements of the software/system. By thinking ahead and investing now you reduce the impact of changes in the future. 3. Code reviews and pair programming, whilst valuable, require a great deal of concentration and rigour. The maintainability testing shall be specified in terms of the effort required to effect a change under each of the following four categories: Corrective maintenance – Correcting problems. Proposed Maintainability Model for Software Development: Design Issues ... IEEE standards glossary of software engineering as “the case with which a software system or a component can be modify to correct faults, improve performances or other attributes or adopt to changed environment”. Can I make a change with only a low risk of breaking existing features? These measures make possible the quantitative assessment of product maintainability. Developing design guidelines demands practical experience and engineering feeling. Are the number and magnitude of such knock-on changes small? 3 0 obj It is embodied in the design of the product. ©2010 - 2020 The University of Edinburgh on Is it easy for me to determine what I need to change as a consequence? What if you need to get a new developer up to speed with your software? R. Malhotra and A. Chug, Software maintainability prediction using machine learning algorithms, Softw. Is it easy to change the code? One measure of maintainability is Time to Repair (TTR, also known as ‘turn-around time’). Maintainable software is software that is easy to understand. 4. But what if those costs could be alleviated - and performance optimized - by encouraging facility professionals to provide input during the design phase of the project? Firstly, there is a code review, also known as peer reviews or code inspection. In engineering, maintainability is the ease with which a product can be maintained in order to: correct defects or their cause, repair or replace faulty or worn-out components without having to replace still working parts, prevent unexpected working conditions, maximize a product's useful life, maximize efficiency, reliability, and safety, meet new requirements, make future maintenance easier, or cope with … Engineering Maintainability How to Design for Reliability and Easy Maintenance. In this way, it can be done as part of the normal development process. Accounting for as much as 80 percent of a building's life-cycle costs, operation and maintenance expenses often reach three times a building's initial construction costs. Because of this it's been found, at least for code reviews, that the first hour of the first code review matter most [2]. << /Length 8 0 R /Type /XObject /Subtype /Form /FormType 1 /BBox [0 0 612 792] So if the software product provides easy maintainability then we can say software quality is up to mark. Software Quality and Maintainability. Minimize spare parts inventory is just one benefit. Book description. Software quality and code quality can make a world of difference for software maintenance. �%>�HE" ߼�E�߉ehK|/zmU~�����c�̫Ƞ�e$��Ab��3�YcN�hM�"��BF'��&. 23 Non-Commercial 2.5 License, Fix a bug, without introducing a new bug as you do so, Add new features, without introducing bugs as you do so, Make a fix that prevents a bug from occurring in future, Make changes to support new environments, operating systems or tools, Bring new developers on board your project, Design for maintainability from the outset, Iterative development and regular reviews help to improve quality - see the section below, Readable code is easy to understand ("write programs for people"), Refactor code to improve its understandability, Relevant documentation helps developers understand the software, Automated build make the code easy to compile, Automated tests make it easy to validate changes, Continuous integration makes the code easier to build and test, Version control helps keep code, tests and documentation up to date and synchronised, Change the way you work to make maintainability a key goal. This book discusses these properties and presents 10 guidelines to help you write source code that is easy to modify. It can make your software more attractive to potential users if they have the confidence that they can fix bugs that arise or add new features they need, if they can be assured that the evolution of the software is not dependant upon the lifetime of your project. The purpose of Reliability and Maintainability (R&M) engineering (Maintainability includes Built-In-Test (BIT)) is to influence system design in order to increase mission capability and availability and decrease logistics burden and cost over a system’s life cycle. %PDF-1.3 Maybe a few months from now you'll realise you need it after all, or you'll have a colleague say "I wish I had a..." and realise you've already made one. It could be important to you that your software is adopted and used by other projects as this may help you get future funding. If I do break something, is it quick and easy to detect and diagnose the problem. << /ProcSet [ /PDF ] /XObject << /Fm1 5 0 R >> >> x�+TT(c}�\C�|�@ 1�� As software guru Martin Fowler said in Refactoring: Improving the Design of Existing Code, 1999, "Good programmers write code that humans can understand.". Attribution Select from the smallest set of parts (one screw instead of 10 different types of screws) with as much compatibility as possible. Today, you have the skills and knowledge to understand and make changes to your software, but what about next week, or six months from now? Can I understand the code? We also use analytics & advertising services. Adaptive maintenance includes the environmental changes where your software is living. This isn't fun, and it wastes valuable time that could be better spent actually improving your software! 12.3.1.1 General Maintainability Design Requirements {A} General requirements to be followed when designing for maintainability are presented below. In changing circumstances adaptive maintenance is required to keep your software fresh or to increase the lifetime of the software. Technical debt is paid off in the cost of maintenance. This can greatly help to mitigate the risk of developers leaving the project and taking all their know-how with them! For this reason, many applications are replaced simply because the overhead to modify them becomes prohibitive. Don’t stop learning now. By table of contents. The software maintenance is an expensive and challenging task. This resource page presents a methodology that links operations and maintenance goals to the design process, and how it can be applied to any organization. 2, 4, 6) as well as by design guidelines and tests (Chaps. Developing maintainable software helps reduce technical debt. Even with the best intentions of everyone involved and regardless of their efforts, the design of a system at some point can IEEE Standard Glossary of Software Engineering Terminology, Refactoring: Improving the Design of Existing Code, A Scientist's Nightmare: Software Problem Leads to Five Retractions, Creating a Maintainable Software Ecosystem, Using Pair Programming Practices in Code Inspections, Design and Code inspections to reduce errors in program development, Creative Commons Bad code requires a larger effort and costs more to adapt to new requirements. Maintainability are the relative costs of fixing, updating, extending, operating and servicing an entity over its lifetime. Reliability, maintainability, and availability (RAM) are three system attributes that are of great interest to systems engineers, logisticians, and users. Can I quickly verify a change (preferably in isolation)? Reliability was first practiced in the early start-up days for the National Aeronautics and Space Administration (NASA) when Robert Lusser, working with Dr. Wernher von Braun's rocketry program, developed what is known as \"Lusser's Law\" . An entity with relatively low costs in these areas is considered maintainable whereas an entity with high costs may be considered unmaintainable or "high maintenance." 9.6 DESIGN FOR RELIABILITY IN SOFTWARE; 9.7 CURRENT BEST PRACTICES IN RELIABILITY ENGINEERING FOR SOFTWARE; 9.8 CHAPTER SUMMARY; 9.9 EXERCISES; REFERENCES; Part II: Maintainability Engineering. Except where otherwise noted, content on this site is licensed under a Creative Commons What if a developer leaves your team (or they fall ill), and you need to take over their code? Maintainable software is software that is easy to understand. endobj Alternatively, it can be done in a more lightweight, informal manner which, if done properly, can be just as effective. Help is at hand! %��������� << /Length 4 0 R /Filter /FlateDecode >> The maintainability of a software system is determined by properties of its source code. Abstract. Software testability is the degree to which a software artifact (i.e. After that, we discuss why maintainability is important. Your guide to asset life cycle design for maintainability and operability. Privacy policy The discipline’s first concerns were electronic and mechanical components (Ebeling, 2010). A good approach to get the most benefit is to employ them for critical portions of critical code, which may be relatively complex and prone to error, and where errors have the highest impact on successful function. You can save time, in the short term, by not commenting code, not refactoring to make it more readable, not addressing compiler warnings, leaving aside tests, skipping documentation and not recording why something was implemented in a specific way. 10 Maintainability Requirements. But can you be sure you'll never want to use it again? 5 0 obj 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. The plan often is to complete these tasks when time permits, and time rarely permits! Save. ). behalf of the Software Sustainability Institute. [0 0 612 792] >> Non-Commercial 2.5 License. Book • 1999 Browse book content. We can advise you on the design and development of maintainable software that will benefit both you and your users. It is code that can be understood by someone new - or someone that hasn't seen it in a while - with a minimum of effort. x��}]s$���{��|\E�����b���Cޕƚ=x��&�͒�*?�M�zW�IV�u� f,=L�T}yO^�~�����1�V��Wʥ�%;�W&��ǻ����f��?��x~?���ޟ���Z��Ov������� bV�G�v��J���f�/?��?���?ߌ��_e�F��~~^��{�q��S��=�p�=�bG��=c��u�al��t���!�p�r We wrote this guide to give an overview of a subject that we think is important to software sustainability. There are a number of principles, approaches and techniques that can help you develop maintainable software. Attribution R. Malhotra and A. Chug, Metric suite for predicting software maintainability in data intensive applications, in Transactions on Engineering Technologies (Springer, 2014), pp. Define the maintainability requirements quantitatively. With an observer as their 'safety net', the driver can focus on the tactical aspects of coding. In this context, maintainability is a function of engineering design. As software guru Martin Fowler said in Refactoring: Improving the Design of Existing Code, 1999, "Good programmers write code that humans can understand." The maintainability of software depends on a few different factors. Once you're finished, leave your spot as you would like to find it yourself, or leave it in a better state than you found it! endobj stream In this chapter, we explain what we mean when we speak about maintainability. If they contribute these back to you, or make them freely available, this can be viewed as free effort for your project. Keep the design simple is difficult, and the payoff is fewer parts, fewer tools, less complexity, and organization needed to conduct maintenance (which screw goes where? It is code that can be understood by someone new - or someone that hasn't seen it in a while - with a minimum of effort. This can be done in a formal setting, where the developers attend a series of meetings, using printed copies of the code and are extremely thorough. Maintainable software is easy to extend and fix, which encourages the software's uptake and use. By these modifications to the environment, changes can occur in the other parts of the software. Growth and Update - Facilities, equipment, and software design shall allow reconfiguration and growth during the mission. 161–175. stream One of the pair acts as a driver who writes the code while the other acts as an observer or navigator who reviews each line of code as it's typed in, and the two switch roles frequently. Maintainability is the degree to which a product allows safe, quick and easy replacement of its component parts. Maintainability – Each software product requires maintenance and up gradation. Every Friday we send out a digest of the week's news and blog posts. 10.1 WHAT TO EXPECT FROM THIS CHAPTER; 10.2 MAINTAINABILITY FOR SYSTEMS ENGINEERS About the book. Maintainability metrics include time requires to adapt to a new features/functionality, Mean Time to Change (MTTC), performance in … The following are illustrative examples. … 5, 3, 7, 8). Software always needs new features or bug fixes. Search in this book. Maintainability is a design characteristic that affects accuracy, ease, and time requirements of maintenance actions. endstream DHILLON. A small investment in the maintainability of your code makes it easier to pick it up after a break, and can provide you with an insurance policy should your disposable software turn out to be more useful than you originally thought. It may be measured by combining factors such as frequency of maintenance, maintenance costs, elapsed maintenance or repair times, and labor hours. Changes to the hardware, operating system, software dependencies, and organizational business rules and policies are handled in adaptive maintenance. Independence - Systems and subsystems shall be as functionally, mechanically, electrically, and electronically independent as practical to facilitate maintenance. Can I explain the rationale behind it to someone else? SAGE Automation , 16 March 2018 (13 min read) Industry continues to face increasing pressure in the management of capital assets: shrinking budgets, increased performance expectations, and evermore regulatory oversight. Measuring maintainability early in the software development life cycle mainly at design phase is a landmark of crucial significance to software designers, developers and quality controllers. Most software engineers would think of some combination of testability, understandability and modifiability of code, as measures of maintainability. The origins of contemporary reliability engineering can be traced to World War II. Reliability is the wellspring for the other RAM system attributes of availability and maintainability. In general, it must be easy to understand the software (how it works, what it does, and why it does it the way it does), easy to find what needs to be change, easy to make changes and easy to check that the changes have not introduced any bugs. /Resources 6 0 R /Filter /FlateDecode >> Software design is an iterative process through which requirements are translated into the blueprint for building the software. endobj So when should you use either of these techniques? Many of these are generally applicable to writing good software: There are a couple of very useful preventative techniques you can consider which can greatly reduce the cost of maintenance. 4 0 obj Design for Reliability and Maintainability Focus on design for reliability and provide a model-based solution that combines capabilities for reliability allocation, reliability block diagrams, and reliability /availability analysis with multiple failure distribution methodologies. Google Scholar; 113. Initial Measurement of object oriented software maintainability, absolutely at design phase supports designers to increase their designs before the coding starts. a software system, software module, requirements- or design document) supports testing in a given test context. Developing maintainable software is like picnicking. [2] "Best Kept Secrets of Peer Code Review", smartbearsoftware.com, ISBN 1599160676 (2006). Maintainable software allows you to quickly and easily: More formally, the IEEE Standard Glossary of Software Engineering Terminology defines maintainability as: "The ease with which a software system or component can be modified to correct faults, improve performance or other attributes, or adapt to a changed environment.". To opt-out click for more information. endobj Here is a list of human factors related, design for maintainability considerations: Consider maintenance from ‘cradle to grave’. A lack of maintainability will be evident as high product maintenance costs, long out-of service times, and possible injuries to maintenance engineers. What if you have to suspend your project whilst you get more funding, and then need to recall all the information about the software a year later?