In the context of software engineering , software quality refers to two related but distinct notions:
59-562: Many aspects of structural quality can be evaluated only statically through the analysis of the software's inner structure, its source code (see Software metrics ), at the unit level, and at the system level (sometimes referred to as end-to-end testing), which is in effect how its architecture adheres to sound principles of software architecture outlined in a paper on the topic by Object Management Group (OMG). Some structural qualities, such as usability , can be assessed only dynamically (users or others acting on their behalf interact with
118-473: A combination of non-compliance with good architectural and coding practices. This non-compliance can be detected by measuring the static quality attributes of an application. Assessing the static attributes underlying an application's reliability provides an estimate of the level of business risk and the likelihood of potential application failures and defects the application will experience when placed in operation. Assessing reliability requires checks of at least
177-535: A given system de facto unsuitable for use regardless of its rating based on aggregated measurements. A well-known example of vulnerability is the Common Weakness Enumeration , a repository of vulnerabilities in the source code that make applications exposed to security breaches. The measurement of critical application characteristics involves measuring structural attributes of the application's architecture, coding, and in-line documentation, as displayed in
236-574: A history of statistical accuracy, and has been used as a common unit of work measurement in numerous application development management (ADM) or outsourcing engagements, serving as the "currency" by which services are delivered and performance is measured. One common limitation to the Function Point methodology is that it is a manual process and therefore it can be labor-intensive and costly in large scale initiatives such as application development or outsourcing engagements. This negative aspect of applying
295-402: A moving target in a competitive market. The word quality has multiple meanings. Two of these meanings dominate the use of the word: 1. Quality consists of those product features which meet the need of customers and thereby provide product satisfaction. 2. Quality consists of freedom from deficiencies. Nevertheless, in a handbook such as this it is convenient to standardize on a short definition of
354-479: A qualitative or a quantitative scoring scheme or a mix of both and then a weighting system reflecting the priorities. This view of software quality being positioned on a linear continuum is supplemented by the analysis of "critical programming errors" that under specific circumstances can lead to catastrophic outages or performance degradations that make a given system unsuitable for use regardless of rating based on aggregated measurements. Such programming errors found at
413-481: A software or system. For example, software maps represent a specialized approach that "can express and combine information about software development, software quality, and system dynamics". Software quality also plays a role in the release phase of a software project. Specifically, the quality and establishment of the release processes (also patch processes ), configuration management are important parts of an overall software engineering process. Software quality
472-433: A software quality management plan)." whereas Software Quality Control (SCQ) means "taking care of applying methods, tools, techniques to ensure satisfaction of the work products toward quality requirements for a software under development or modification." The first definition of quality history remembers is from Shewhart in the beginning of 20th century: "There are two common aspects of quality: one of them has to do with
531-432: A specification on the final result of a program) is undecidable : there is no mechanical method that can always answer truthfully whether an arbitrary program may or may not exhibit runtime errors. This result dates from the works of Church , Gödel and Turing in the 1930s (see: Halting problem and Rice's theorem ). As with many undecidable questions, one can still attempt to give useful approximate solutions. Some of
590-506: A standard, framework, or practice guide, the PMI Lexicon of Project Management Terms offers clear and concise definitions for nearly 200 of the profession's frequently used terms. Definitions in the Lexicon were developed by volunteer experts, and PMI standards committees are chartered to use the Lexicon terms without modification. Version 3.2 contains numerous revised terms based on requests from
649-415: A variety of ways such as taking classes, attending PMI global congresses, contributing to professional research, or writing and publishing papers on the subject. Most credentials must be renewed every three years. These are the certifications and credentials offered by PMI: PMI also provided a Certified OPM3 Professional credential which was officially discontinued on March 1, 2017. PMI no longer allows
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#1733094269387708-480: Is "Quality is value to some person." One of the challenges in defining quality is that "everyone feels they understand it" and other definitions of software quality could be based on extending the various descriptions of the concept of quality used in business. Software quality also often gets mixed-up with Quality Assurance or Problem Resolution Management or Quality Control or DevOps . It does over-lap with before mentioned areas (see also PMI definitions), but
767-439: Is about quantifying to what extent a system or software possesses desirable characteristics. This can be performed through qualitative or quantitative means or a mix of both. In both cases, for each desirable characteristic, there are a set of measurable attributes the existence of which in a piece of software or system tend to be correlated and associated with this characteristic. For example, an attribute associated with portability
826-516: Is closely related to Ward Cunningham's concept of technical debt , which is an expression of the costs resulting of a lack of maintainability. Reasons for why maintainability is low can be classified as reckless vs. prudent and deliberate vs. inadvertent, and often have their origin in developers' inability, lack of time and goals, their carelessness and discrepancies in the creation cost of and benefits from documentation and, in particular, maintainable source code . Measuring software size requires that
885-601: Is distinctive as it does not solely focus on testing but also on processes, management, improvements, assessments, etc. Although the concepts presented in this section are applicable to both structural and functional software quality, measurement of the latter is essentially performed through software testing . Testing is not enough: According to one study, "individual programmers are less than 50% efficient at finding bugs in their own software. And most forms of testing are only 35% efficient. This makes it difficult to determine [software] quality." Software quality measurement
944-516: Is in the verification of properties of software used in safety-critical computer systems and locating potentially vulnerable code. For example, the following industries have identified the use of static code analysis as a means of improving the quality of increasingly sophisticated and complex software: A study in 2012 by VDC Research reported that 28.7% of the embedded software engineers surveyed use static analysis tools and 39.7% expect to use them within 2 years. A study from 2010 found that 60% of
1003-405: Is motivated by at least two main perspectives: Software quality is the "capability of a software product to conform to requirements." while for others it can be synonymous with customer- or value-creation or even defect level. Software quality measurements can be split into three parts: process quality, product quality which includes internal and external properties and lastly, quality in use, which
1062-498: Is possible to design and implement automated remediation techniques. For example, Logozzo and Ball have proposed automated remediations for C# cccheck . Project Management Institute The Project Management Institute ( PMI , legally Project Management Institute, Inc. ) is a U.S.-based not-for-profit professional organization for project management . PMI serves more than five million professionals including over 680,000 members in 217 countries and territories around
1121-416: Is represented in the diagram on the right, where each of the 5 characteristics that matter for the user (right) or owner of the business system depends on measurable attributes (left): Correlations between programming errors and production defects unveil that basic code errors account for 92 percent of the total errors in the source code. These numerous code-level issues eventually count for only 10 percent of
1180-491: Is the analysis of computer programs performed without executing them, in contrast with dynamic program analysis , which is performed on programs during their execution in the integrated environment. The term is usually applied to analysis performed by an automated tool, with human analysis typically being called "program understanding", program comprehension , or code review . In the last of these, software inspection and software walkthroughs are also used. In most cases
1239-448: Is the approach taken in the ISO 9126 and 25000 series standards. These attributes can be measured from the parsed results of a static analysis of the application source code. Even dynamic characteristics of applications such as reliability and performance efficiency have their causal roots in the static structure of the application. Structural quality analysis and measurement is performed through
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#17330942693871298-593: Is the effect of the software. ASQ uses the following definition: Software quality describes the desirable attributes of software products. There are two main approaches exist: defect management and quality attributes. Software Assurance (SA) covers both the property and the process to achieve it: The Project Management Institute 's PMBOK Guide "Software Extension" defines not "Software quality" itself, but Software Quality Assurance (SQA) as "a continuous process that audits other software processes to ensure that those processes are being followed (includes for example
1357-536: Is the number of target-dependent statements in a program. More precisely, using the Quality Function Deployment approach, these measurable attributes are the "hows" that need to be enforced to enable the "whats" in the Software Quality definition above. The structure, classification and terminology of attributes and metrics applicable to software quality management have been derived or extracted from
1416-536: Is the term applied to the analysis of software (and computer hardware ) whose results are obtained purely through the use of rigorous mathematical methods. The mathematical techniques used include denotational semantics , axiomatic semantics , operational semantics , and abstract interpretation . By a straightforward reduction to the halting problem , it is possible to prove that (for any Turing complete language), finding all possible run-time errors in an arbitrary program (or more generally any kind of violation of
1475-487: The Consortium for IT Software Quality (CISQ) has defined five major desirable structural characteristics needed for a piece of software to provide business value : Reliability, Efficiency, Security, Maintainability, and (adequate) Size. Software quality measurement quantifies to what extent a software program or system rates along each of these five dimensions. An aggregated measure of software quality can be computed through
1534-691: The Georgia Institute of Technology in 1969 as a nonprofit organization. It was incorporated in the state of Pennsylvania in the same year. PMI described its objectives in 1975 as to "foster recognition of the need for professionalism in project management; provide a forum for the free exchange of project management problems, solutions, and applications; coordinate industrial and academic research efforts; develop common terminology and techniques to improve communications; provide an interface between users and suppliers of hardware and software systems; and to provide guidelines for instruction and career development in
1593-453: The ISO 9126-3 and the subsequent ISO/IEC 25000:2005 quality model. The main focus is on internal structural quality. Subcategories have been created to handle specific areas like business application architecture and technical characteristics such as data access and manipulation or the notion of transactions. The dependence tree between software quality characteristics and their measurable attributes
1652-775: The ANSI/ISO/IEC 17024 accreditation from the International Organization for Standardization (ISO). As of May 2020 , over one million people held the PMP credential. PMI later introduced other certifications. Credential holders do not have to be members of PMI. To initially obtain a PMI credential, candidates must first document that they have met the required education and experience requirements. They must then pass an examination consisting of multiple-choice questions. To maintain most PMI credentials, holders must earn Professional Development Units (PDUs), which can be earned in
1711-837: The Project Management Body of Knowledge ", which has been recognized by the American National Standards Institute (ANSI). In 2012 ISO adapted the project management processes from the PMBOK Guide 4th edition. In the 1960s project management as such began to be used in the US aerospace, construction, and defense industries. The Project Management Institute was founded by Ned Engman (McDonnell Douglas Automation), James Snyder , Susan Gallagher (SmithKline & French Laboratories), Eric Jenett (Brown & Root), and J Gordon Davis (Georgia Institute of Technology) at
1770-571: The SDL defined by Microsoft and a common practice in software companies. The OMG ( Object Management Group ) published a study regarding the types of software analysis required for software quality measurement and assessment. This document on "How to Deliver Resilient, Secure, Efficient, and Easily Changed IT Systems in Line with CISQ Recommendations" describes three levels of software analysis. A further level of software analysis can be defined. Formal methods
1829-487: The SEI/Computer Emergency Center (CERT) at Carnegie Mellon University. Assessing security requires at least checking the following software engineering best practices and technical attributes: Maintainability includes concepts of modularity, understandability, changeability, testability, reusability, and transferability from one development team to another. These do not take the form of critical issues at
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1888-480: The US federal government directly; several members were federal employees in agencies involved with project management. In the 1980s, efforts were made to standardize project management procedures and approaches. The PMI produced the first Project Management Body of Knowledge (PMBOK) in 1996. In the late 1990s, Virgil R. Carter became president of the PMI. In 2002 Carter was succeeded by Gregory Balestrero , who directed
1947-401: The analysis is performed on some version of a program's source code , and, in other cases, on some form of its object code . The sophistication of the analysis performed by tools varies from those that only consider the behaviour of individual statements and declarations, to those that include the complete source code of a program in their analysis. The uses of the information obtained from
2006-499: The analysis of the source code , the architecture , software framework , database schema in relationship to principles and standards that together define the conceptual and logical architecture of a system. This is distinct from the basic, local, component-level code analysis typically performed by development tools which are mostly concerned with implementation considerations and are crucial during debugging and testing activities. The root causes of poor reliability are found in
2065-537: The analysis vary from highlighting possible coding errors (e.g., the lint tool) to formal methods that mathematically prove properties about a given program (e.g., its behaviour matches that of its specification). Software metrics and reverse engineering can be described as forms of static analysis. Deriving software metrics and static analysis are increasingly deployed together, especially in creation of embedded systems, by defining so-called software quality objectives . A growing commercial use of static analysis
2124-447: The code level. Rather, poor maintainability is typically the result of thousands of minor violations with best practices in documentation, complexity avoidance strategy, and basic programming practices that make the difference between clean and easy-to-read code vs. unorganized and difficult-to-read code. Assessing maintainability requires checking the following software engineering best practices and technical attributes: Maintainability
2183-425: The consideration of the quality of a thing as an objective reality independent of the existence of man. The other has to do with what we think, feel or sense as a result of the objective reality. In other words, there is a subjective side of quality." Kitchenham and Pfleeger, further reporting the teachings of David Garvin, identify five different perspectives on quality: The problem inherent in attempts to define
2242-401: The defects in production. Bad software engineering practices at the architecture levels account for only 8 percent of total defects, but consume over half the effort spent on fixing problems, and lead to 90 percent of the serious reliability, security, and efficiency issues in production. Many of the existing software measures count structural elements of the application that result from parsing
2301-424: The factors being measured]. This view of software quality on a linear continuum has to be supplemented by the identification of discrete Critical Programming Errors . These vulnerabilities may not fail a test case, but they are the result of bad practices that under specific circumstances can lead to catastrophic outages, performance degradations, security breaches, corrupted data, and myriad other problems that make
2360-782: The field of project management." In the 1970s standardization efforts represented 10 to 15 percent of the institute's efforts. The functions were performed through the Professional Liaison Committee which called on and coordinated with the Technology, Research Policy, and Education Committees. The institute participated in national activities through the American National Standards Committee XK 36.3 and internationally, through liaison with an appointed observer to Europe's International Project Management Association, then called INTERNET. PMI did not deal with
2419-534: The following software engineering best practices and technical attributes: Depending on the application architecture and the third-party components used (such as external libraries or frameworks), custom checks should be defined along the lines drawn by the above list of best practices to ensure a better assessment of the reliability of the delivered software. As with Reliability, the causes of performance inefficiency are often found in violations of good architectural and coding practice which can be detected by measuring
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2478-442: The functional size of software and Automated Enhancement Points to measure the size of both functional and non-functional code in one measure. Critical Programming Errors are specific architectural and/or coding bad practices that result in the highest, immediate or long term, business disruption risk. Static testing In computer science , static program analysis (also known as static analysis or static simulation )
2537-510: The implementation techniques of formal static analysis include: Data-driven static analysis leverages extensive codebases to infer coding rules and improve the accuracy of the analysis. For instance, one can use all Java open-source packages available on GitHub to learn good analysis strategies. The rule inference can use machine learning techniques. It is also possible to learn from a large amount of past fixes and warnings. Static analyzers produce warnings. For certain types of warnings, it
2596-497: The institute until his retirement in January 2011. He was succeeded as President and CEO by Mark A. Langley. From March 2019 through December 2021 the president and CEO was Sunil Prashara. Pierre Le Manh was appointed CEO on September 1, 2022. Launched in 1984, PMI's first credential was the PMP . It has since become a de facto standard certification in project management. In 2007 it earned
2655-453: The interviewed developers in European research projects made at least use of their basic IDE built-in static analyzers. However, only about 10% employed an additional other (and perhaps more advanced) analysis tool. In the application security industry the name static application security testing (SAST) is also used. SAST is an important part of Security Development Lifecycles (SDLs) such as
2714-639: The methodology may be what motivated industry IT leaders to form the Consortium for IT Software Quality focused on introducing a computable metrics standard for automating the measuring of software size while the IFPUG keep promoting a manual approach as most of its activity rely on FP counters certifications. CISQ defines Sizing as to estimate the size of software to support cost estimating, progress tracking or other related software project management activities. Two standards are used: Automated Function Points to measure
2773-456: The needs of the consumer have changed, competitors have moved in, etc. Quality is a customer determination, not an engineer's determination, not a marketing determination, nor a general management determination. It is based on the customer's actual experience with the product or service, measured against his or her requirements -- stated or unstated, conscious or merely sensed, technically operational or entirely subjective -- and always representing
2832-445: The picture above. Thus, each characteristic is affected by attributes at numerous levels of abstraction in the application and all of which must be included in calculating the characteristic's measure if it is to be a valuable predictor of quality outcomes that affect the business. The layered approach to calculating characteristic measures displayed in the figure above was first proposed by Boehm and his colleagues at TRW (Boehm, 1978) and
2891-400: The quality of a product, almost any product, was stated by the master Walter A. Shewhart. The difficulty in defining quality is to translate the future needs of the user into measurable characteristics, so that a product can be designed and turned out to give satisfaction at a price that the user will pay. This is not easy, and as soon as one feels fairly successful in the endeavor, he finds that
2950-426: The quality related attributes. Functional quality is typically assessed dynamically but it is also possible to use static tests (such as software reviews ). Historically, the structure, classification, and terminology of attributes and metrics applicable to software quality management have been derived or extracted from the ISO 9126 and the subsequent ISO/IEC 25000 standard. Based on these models (see Models),
3009-534: The software development life-cycle and it is not dependent on lines of code like the somewhat inaccurate Backfiring method. The method is technology agnostic and can be used for comparative analysis across organizations and across industries. Since the inception of Function Point Analysis, several variations have evolved and the family of functional sizing techniques has broadened to include such sizing measures as COSMIC, NESMA, Use Case Points, FP Lite, Early and Quick FPs, and most recently Story Points. Function Point has
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#17330942693873068-470: The software or, at least, some prototype or partial implementation; even the interaction with a mock version made in cardboard represents a dynamic test because such version can be considered a prototype). Other aspects, such as reliability, might involve not only the software but also the underlying hardware, therefore, it can be assessed both statically and dynamically ( stress test ). Using automated tests and fitness functions can help to maintain some of
3127-422: The source code for such individual instructions tokens control structures ( Complexity ), and objects. Software quality measurement is about quantifying to what extent a system or software rates along these dimensions. The analysis can be performed using a qualitative or quantitative approach or a mix of both to provide an aggregate view [using for example weighted average(s) that reflect relative importance between
3186-649: The static quality attributes of an application. These static attributes predict potential operational performance bottlenecks and future scalability problems, especially for applications requiring high execution speed for handling complex algorithms or huge volumes of data. Assessing performance efficiency requires checking at least the following software engineering best practices and technical attributes: Software quality includes software security . Many security vulnerabilities result from poor coding and architectural practices such as SQL injection or cross-site scripting. These are well documented in lists maintained by CWE, and
3245-630: The system level represent up to 90 percent of production issues, whilst at the unit-level, even if far more numerous, programming errors account for less than 10 percent of production issues (see also Ninety–ninety rule ). As a consequence, code quality without the context of the whole system, as W. Edwards Deming described it, has limited value. To view, explore, analyze, and communicate software quality measurements, concepts and techniques of information visualization provide visual, interactive means useful, in particular, if several software quality measures have to be related to each other or to components of
3304-508: The use of the credential's designation by individuals who formerly obtained it. OPM3 , even though no longer neither a credential nor a publication, remains a registered mark of PMI. List of PMI Micro-Credentials: The standards PMI develops and publishes fall into three main categories: Here is a list of the current standards or guides in each category: Foundational Standards Practice Standards and Frameworks Practice Guides PMI Lexicon of Project Management Terms While not
3363-507: The whole source code be correctly gathered, including database structure scripts, data manipulation source code, component headers, configuration files etc. There are essentially two types of software sizes to be measured, the technical size (footprint) and the functional size: The function point analysis sizing standard is supported by the International Function Point Users Group ( IFPUG ). It can be applied early in
3422-501: The word quality as "fitness for use". Tom DeMarco has proposed that "a product's quality is a function of how much it changes the world for the better." This can be interpreted as meaning that functional quality and user satisfaction are more important than structural quality in determining software quality. Another definition, coined by Gerald Weinberg in Quality Software Management: Systems Thinking,
3481-402: The world, with 304 chapters and 14,000 volunteers serving local members in over 180 countries. Its services include the development of standards, research, education, publication, networking opportunities in local chapters, hosting conferences and training seminars, and providing accreditation in project management. PMI has recruited volunteers to create industry standards, such as " A Guide to
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