software reusability tutorialspoint

Another type of these requirements deals with automatic diagnostic checks applied by the maintenance technicians to detect the causes of software failures. The length of the program can be measured by counting the lines of code. They determine the maximum allowed failure rate of the software system, and can refer to the entire system or to one or more of its separate functions. This class of components deal with several goals, such as the control of development and maintenance activities, and the introduction of early managerial support actions that mainly prevent or minimize schedule and budget failures and their outcomes. Similarly, models consisting of 12 to 15 factors, were suggested by Deutsch and Willis (1988) and by Evans and Marciniak (1987). Tutorial, software reusability on [Boehm et al 1978] B.W. This is an extension of the defect density metric during testing. For example: The total number of failures experienced by a user, the length of time it takes to search the database and retrieve information. There are two cases of data to be considered: normal data and non-normal data. There is a zero element, representing total lack of the attributes. It differs from hardware reliability in that it reflects the design perfection, rather than manufacturing perfection. If the defect backlog is large at the end of the development cycle and a lot of fixes have yet to be integrated into the system, the stability of the system (hence its quality) will be affected. In an industrial product, defects can be detected during the following phases −. In case of software, product production planning and manufacturing phases are not required as the manufacturing of software copies and the printing of software manuals are conducted automatically. Increase return on investment (ROI) 2. It should not be limited by established dimensions of a given process maturity model. All of these entities have internal as well as external entities. Software exits in different forms throughout the software engineering process. Customer satisfaction is often measured by customer survey data through the five-point scale −, Satisfaction with the overall quality of the product and its specific dimensions is usually obtained through various methods of customer surveys. Hence, the data should also be possible to replicate easily. found that a count of objects and methods led to more accurate productivity estimates than those using lines of code. In a software lifetime, type of maintenance may vary based on its nature. It measures any software product that can be modeled as an algorithm. At this level, the inputs and outputs of the process, constraints, and resources are identifiable. This metric can be calculated for the entire development process, for the front-end before code integration and for each phase. The representatives of the site to be appraised complete the standard process maturity questionnaire. Reusability • Software development process called frameworks that promotes reuse. For example, if we want to determine whether a change in the programming language can affect the productivity of the project, then the language will be a state variable. 2. In this case, we have no control over the situation at hand. It identifies the software as a system with many components interacting with each other. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. For validating a measurement system, we need both a formal model that describes entities and a numerical mapping that preserves the attribute that we are measuring. Productivity can be considered as a function of the value and the cost. This scale captures the information about the size of the intervals that separate the classification. FTR − The number of files updated or referenced. Complexity of a problem − It is the amount of resources required for an optimal solution to the problem. Software Quality Management is a process that ensures the required level of software quality is achieved when it reaches the users, so that they are satisfied by its performance. SQA trustees are those members who are primarily involved in the promotion of software quality. Reusability • Software development process called frameworks that promotes reuse. The control flow measures are usually modeled with directed graph, where each node or point corresponds to program statements, and each arc or directed edge indicates the flow of control from one statement to another. [Bassett 1997] Paul G. Bassett: Framing Software Reuse: Lessons From the Real World. If BMI is less than 100, then the backlog increased. The defect arrivals or defects reported during the testing phase by time interval (e.g., week). The organization being assessed must have members on the assessment team. Normally, a software is developed for a contract negotiated with a customer or for an internal order to develop a firmware to be embedded within a hardware product. Product operation factors − Correctness, Reliability, Efficiency, Integrity, Usability. $$DRE = \frac{Defect \: removed \: during \: a \: development\:phase }{Defects\: latent \: in \: the\: product} \times 100\%$$. Reduce overtime 5. Thus, measurement will help us compare an item with another. Hence, the main engineering tasks involve the following −, Testing quality and productivity aspects with respect to new development tools and new versions of currently used development tools, Evaluation of quality and productivity of new development and maintenance methods and method improvements, Development of solutions to difficulties confronted in application of currently used software development tools and methods, Development of methods for measuring software quality and team productivity, Provision of technological support to CAB committees during analysis of software development failures and formulation of proposed solutions, SQA information systems are meant to facilitate and improve the functioning of SQA systems. Even in what appears to be the same organization, the sample of projects selected to represent the organization may affect the scope and outcome. All these models do not differ substantially from McCall’s model. The different external attributes of a process are cost, controllability, effectiveness, quality and stability. If the activity has already occurred, we can perform survey or case study. It places the elements in an ordered classification scheme. The main objectives of this class are utilization of international professional knowledge, improvement of coordination of the organizational quality systems with other organizations, and assessment of the achievements of quality systems according to a common scale. The tasks involved include −, Development of SQA information systems for software development and maintenance units for, processing of, for example, periodic reports, lists, exception reports and queries, Development of SQA information systems facilitating the SQA unit’s processing of information delivered by software development and maintenance units including estimates of software quality metrics and software quality costs, Development and maintenance of the organization’s SQA Internet /Intranet site. Cost and effort estimation models have been proposed to predict the project cost during early phases in the software life cycle. Was the application developed to meet one or many user’s needs? Software reliability testing a testing technique that relates to testing a software's ability to function given environmental conditions consistently that helps uncover issues in the software design and functionality. These plans include additional details and needed revisions based on prior plans that provided the basis for the current proposal and contract. Validating a software measurement system is the process of ensuring that the measure is a proper numerical characterization of the claimed attribute by showing that the representation condition is satisfied. Usability Testing Process: Previous Page Print Page. Work on software reusability, which can be regarded as encompassing automatic programming, strives to devise methods, architectures and tools to allow knowledge about one software system to be reused to build a different software system. These are measurements that can be measured in terms of any other entity or attribute. Component Reusability Watch more Videos at Lecture By: Mr. Arnab Chakraborty, Tutorials Point … Are they correct? The requirements specification, the architectural design, and the source code are all software in different formats.Software reusability includes the reuse of any software artifacts in various formats. It ensures that what is built is what is delivered. Was the application designed for end-user efficiency? Software reliability is a term to be avoided, though it is used widely and there are suggestions that the term reliable software could be used instead. The results of an experiment are usually more generalizable than case study or survey. This model classifies all software requirements into 11 software quality factors. When the assessment target is the organization, the results of a process assessment may differ, even on successive applications of the same method. Another measure for non-normal data is the Kendall robust correlation coefficient, which investigates the relationship among pairs of data points and can identify a partial correlation. • Systematic software reuse is still the most promising strategy for increasing productivity and improving quality in the software industry. Tutorial, software reusability The upper branches hold important high level quality factors such as reliability and usability. Software is rarely built completely from scratch. − Precision deals with the number of decimal places needed to express the data. The metric of percent defective fixes is the percentage of all fixes in a time interval that is defective. Specifically, contract review activities include −, Clarification of the customer’s requirements, Review of the project’s schedule and resource requirement estimates, Evaluation of the professional staff’s capacity to carry out the proposed project, Evaluation of the customer’s capacity to fulfil his obligations. SOFTWARE REUSE • Software reuse is the use of existing software or software knowledge to build new software for an individual or an organization. Assuring with an acceptable level of confidence that the software maintenance activities will conform to the functional technical requirements. Software reliability is a term to be avoided, though it is used widely and there are suggestions that the term reliable software could be used instead. Examples include the number of software developers, the staffing pattern over the life cycle of the software, cost, schedule, and productivity. At the same time, the complexity of analysis can influence the design chosen. SQA incorporates and implements software testing methodologies to test the software. Some stochastic prediction systems are more stochastic than others. For the unary relation ‘is tall’, we might have the numerical relation. of mental comparisons needed to write a program of length N, is. Software metrics is a standard of measure that contains many activities, which involves some degree of measurement. We can record a situation and compare it with a similar one. A second-party assessment is performed by an external assessment team or the organization is assessed by a customer. Complexity of a solution − It is the resources needed to implement a particular solution. After signing the software development contract with an organization or an internal department of the same organization, a development plan of the project and its integrated quality assurance activities are prepared. In this chapter, we will discuss the roles and responsibilities of each sub-unit. We'll also discuss another category of design pattern: J2EE design patterns. For example −. from the viewpoint of the developer, manager, customer, etc. The numbers represent ranking only. This factor deals with the software system security, that is, to prevent access to unauthorized persons, also to distinguish between the group of people to be given read as well as write permit. It is applicable for those applications where data is batched, and each subsystem reads related input fil… The GQM approach provides a framework involving the following three steps −, Listing the major goals of the development or maintenance project, Deriving the questions from each goal that must be answered to determine if the goals are being met, Decide what must be measured in order to be able to answer the questions adequately. Prediction systems are used to predict some attribute of a future entity involving a mathematical model with associated prediction procedures. Hence, assuring of all these operational possibilities correctly is a major challenge to the software industry. Yourdon Press Computing Series, ISBN 0-13-327859-X, Prentice Hall, 1997. This factor’s requirements also support perfective maintenance activities, such as changes and additions to the software in order to improve its service and to adapt it to changes in the firm’s technical or commercial environment. Together they provide a context for measurement. Multiple groups use F-statistics rather than Student’s T-test with two groups. These factors are as follows −. $$BMI = \frac{Number \: of \: problems \: closed \: during \:the \:month }{Number \: of \: problems \: arrived \: during \:the \:month} \times 100\%$$. For example, to compare height, we use the terms ‘taller than’, higher than’. It includes processing capabilities (given in MHz), its storage capacity (given in MB or GB) and the data communication capability (given in MBPS or GBPS). The process will act as sensors and monitors, and we can change the process significantly in response to warning signs. The 11 factors are grouped into three categories – product operation, product revision, and product transition factors. TickIT, now managed and maintained by the DISC Department of BSI (the British Standards Institute), is accredited for the certification of IT organizations in the UK and Sweden. Reduce costsThese goals ca… It is also based on the CBA IPI. Corrective Maintenance - This includes modifications and updations done in order to correct or fix problems, which are either di… These factors are as follows −. Safety-critical software is called reliable software. $$\small Programmer\:Productivity = \frac{LOC \: produced }{Person \:months \:of \:effort}$$, $\small Module\:Defect\:Density = \frac{Number \:of\:defects}{Module \:size}$, $$\small Defect\:Detection\:Efficiency = \frac{Number \:of\:defects\:detected}{Total \:number \:of\:defects}$$, $\small Requirement\:Stability = \frac{Number \:of\:initial\:requirements}{Total \:number \:of\:requirements}$, $\small Test\:Effectiveness\:Ratio = \frac{Number \:of\:items\:covered}{Total \:number \:of \:items}$, $\small System\:spoilage = \frac{Effort \:spent\:for\:fixing\:faults}{Total \:project \:effort}$. Architectural Design - The architectural design is the highest abstract version of the system. There are three major items to consider for choosing the analysis technique. Example: To characterize the product in order to learn it. It is of two types −. Reusability is the degree to which a thing can be reused. Usability requirements deal with the staff resources needed to train a new employee and to operate the software system. Using it in the format of a trend chart, this metric can provide meaningful information for managing the maintenance process. For an organization to function effectively, it has to determine and manage numerous linked activities. At this level, the inputs are ill- defined, while the outputs are expected. Example − ISO 9000-3 and the Capability Maturity Model (CMM), These focus on the methodologies for implementing the software development and maintenance projects. It ensures that developed software meets and complies with the defined or standardized quality specifications. How many communication facilities are there to aid in the transfer or exchange of information with the application or system? A scatter plot represents the relationship between two variables. Registered lead auditors are required to have a demonstrated experience in conducting and directing TickIT audits. Reuse Practiced by Software Engineers 1. It should maintain the balance for both novice and expert user. The measurement is made by counting the number of elements in the entity set. Activities during this process: Configuration auditing is conducted by auditors by checking that defined processes are being followed and ensuring that the SCM goals are satisfied. For example, the in-process quality metrics of a project are both process metrics and project metrics. The quality goal for the maintenance process, of course, is zero defective fixes without delinquency. They are −. Recommended for you Example: Examine the defects from the viewpoint of the customer. Software Reliability is the probability of failure-free software operation for a specified period of time in a specified environment. If the data is non-normal, then the data can be analyzed using Kruskal-Wallis test by ranking it. Was the application specifically designed, developed, and supported to be installed at multiple sites for multiple organizations? Dr. Edward Lavieri. This metric is mostly used with safety critical systems such as the airline traffic control systems, avionics, and weapons. In a shop, the price acts as a measure of the value of an item. Software Structural Quality − It deals with the handling of non-functional requirements that support the delivery of the functional requirements, such as robustness or maintainability, and the degree to which the software was produced correctly. Measurement is the action of measuring something. Measurement tells us the rules laying the ground work for developing and reasoning about all kinds of measurement. The SQA components used during the operation–maintenance phase include specialized maintenance components as well as development life cycle components, which are applied mainly for functionality to improve the maintenance tasks. Identify areas of improvement 3. This assures that the project commitments have been clearly defined considering the resources required, the schedule and budget; and the development and quality plans have been correctly determined. Manage workloads 4. These include adapting the current software to additional circumstances and customers without changing the software. A distinct final formula is used for each count type: Application, Development Project, or Enhancement Project. The problems metric is usually expressed in terms of Problems per User-Month (PUM). The SQA organizational base includes managers, testing personnel, the SQA unit and the persons interested in software quality such as SQA trustees, SQA committee members, and SQA forum members. Assuring an acceptable level of confidence that the software will conform to managerial scheduling and budgetary requirements. At this level, intermediate activities are defined, and their inputs and outputs are known and understood. With regard to the metrics for the design and coding phases, in addition to defect rates, many development organizations use metrics such as inspection coverage and inspection effort for in-process quality management. Hence, addition, subtraction, and other arithmetic operations have no meaning. The team must consist of between four to ten team members. What is Software Reusability? The different internal attributes for the resources are age, price, size, speed, memory size, temperature, etc. They also provide SQA certification through independent professional quality audits. If it is yet to occur, then case study or formal experiment may be chosen. The current guide (edition 5.0, TickIT, 2001), which includes references to ISO/IEC 12207 and ISO/IEC 15504, is distributed to all TickIT customers. This factor deals with the capabilities and efforts required to support adaptive maintenance activities of the software. There are two reasons for the different results. These members provide the internal support necessary for successfully implementing SQA components. Software design yields three levels of results: 1. Draft of the International Standards adopted by the technical committees is circulated to the member bodies for voting. Assuring an acceptable level of confidence that the software will conform to functional technical requirements. After collecting relevant data, we have to analyze it in an appropriate way. DOI: 10.1007/978-3-662-03345-6. Their tasks include −, Preparation of project plans and project quality plans, Choice of measures to solve identified software development risks, Choice of measures to solve schedule delays and budget overruns, Choice of SQA metrics and software costs components, Choice of development methodologies and tools that reflect the failure experience data accumulated by the SQA unit, The SQA sub-unit is intimately involved in deciding which SQA standards will be adopted as well as developing and maintaining the organization’s procedures. Following are some types of maintenance based on their characteristics: 1. At this level, the feedback from the early project activities can be used to set priorities for the current activities and later for the project activities. Basically, a three-level structure of management exists in software development organizations −, Following are the responsibilities of the top management in ensuring Software Quality −, Assure the quality of the company’s software products and software maintenance services, Communicate the importance of the product and service quality in addition to customer satisfaction to employees at all levels, Assure satisfactory functioning and full compliance with customer requirements, Ensure that quality objectives are established for the organization’s SQA system and that its objectives are accomplished, Initiate planning and oversee implementation of changes necessary to adapt the SQA system to major internal as well as external changes related to the organization’s clientele, competition, and technology, Intervene directly to support resolution of crisis situations and minimize damages, Ensure the availability of resources required by SQA systems, The following steps can be taken by the top management to fulfill its responsibilities −. Data structure measures can then be defined hierarchically in terms of values for the primes and values associated with the various operations. Software metrics contains many activities which include the following −. For example − This software performs well. [Biggerstaff 1989] T. J. Biggerstaff: Design Recovery for Maintenance and Reuse. The goal and question analysis will be the same, but the metric will vary with maturity. Different code libraries classes should be generic enough to use easily in different application modules. His tasks include professional hands-on and managerial tasks, particularly the following −, Preparation of project and quality plans and their updates, Participation in joint customer–supplier committee, Close follow-up of project team staffing, including attending to recruitment, training and instruction, Project managers address the follow-up issues such as −, Performance of review activities and the consequent corrections, Software development and maintenance unit’s performance, integration and system test activities as well as corrections and regression tests, Software installation in remote customer sites and the execution of the software system by the customer, SQA training and instruction of project team members, Schedules and resources allocated to project activities, Evolving project development risks, application of solutions and control of results. Different possible components of a productivity model can be expressed in the following diagram. 36-49. FP (Function Point) is the most widespread functional type metrics suitable for quantifying a software application. Product metrics describe the characteristics of the product such as size, complexity, design features, performance, and quality level. i.e., it measures code quality per unit. All these functionalities need to be necessarily incorporated into the system as a part of the contract. A self-assessment (first-party assessment) is performed internally by an organization's own personnel. For the Love of Physics - Walter Lewin - May 16, 2011 - Duration: 1:01:26. For example, the firmware of the production machinery and testing equipment interfaces with the production control software. At present, the ISO 9000 Certification Service is the most prominent provider of SQA certification in Europe and other countries. On a more granular level, software development managers are trying to: 1. Function point analysis is a standard method for measuring software development from the user's point of view. The assessment team conducts a site visit to gain an understanding of the software process followed by the site. The various factors, which influence the software, are termed as software factors. It differs from hardware reliability in that it reflects the design … Measurement is a direct quantification whereas calculation is an indirect one where we combine different measurements using some formulae. Then we try to establish empirically predictive theories to support quality assurance, quality control, and quality prediction. He earned a Doctorate of Computer Science from Colorado Technical University, an MS in Management Information Systems (Bowie State University), an MS in Education (Capella University), and an MS in Operations Management (University of Arkansas). In computer science and software engineering, reusability is the use of existing assets in some form within the software product development process; these assets are products and by-products of the software development life cycle and include code, software components, test suites, designs and documentation. The measurement reflects the characteristics of the overall process and of the interaction among and across major activities. The diagrams in the documents have uniform syntax such as labelled digraphs, data-flow diagrams or Z schemas. • Software reuse is also called as “Code Reuse”. Interoperability requirements focus on creating interfaces with other software systems or with other equipment firmware. The difference between the two dates is the latent period of the defective fix. It is a research technique where you identify the key factors that may affect the outcome of an activity and then document the activity: its inputs, constraints, resources, and outputs. There are many software measures to capture the value of an attribute. Advertisements. This metric is needed because development organizations cannot investigate and fix all the reported problems immediately. One aspect of complexity is efficiency. The main objective of these components, which is applied throughout the entire organization, is to eliminate or at least reduce the rate of errors, based on the organization’s accumulated SQA experience. A model should also specify how these entities are related to the attributes and how the characteristics relate. The most commonly used traditional measure of source code program length is the Lines of code (LOC). For this level of process maturity, baseline measurements are needed to provide a starting point for measuring. This difference is due to the following reasons. According to McCall’s model, three software quality factors are included in the product revision category. For example: Rank the following 5 software modules according to their performance. Thus, these ‘taller than’, higher than’ are empirical relations for height. This tutorial provides a complete overview of Software Quality Management and describes the various steps involved in the process. The improvement in the process or products can be performed only when the project has clearly defined goals for processes and products. These components can be classified into the following six classes −. The responsibilities include −, Review of trends that are expected to affect the organization’s software quality in the near future, Review proposals for SQA adaptations such as preparation of new procedures appropriate to the new tools and SQA standards, Preparation of training programs for veteran software development teams and newly recruited team members, Development of software quality metrics appropriate for evaluating the new tools and standards as well as the success of the training programs, Approval of the final version of the planned SQA development projects, including their schedules and budgets, The executive in-charge is responsible for −, General supervision of the annual activities program, Review of the progress of the SQA adaptation projects, General supervision of the actions taken to realize the quality achievements dictated by the teams’ objectives (based on periodic reports), Review of compliance with SQA procedures and standards based on internal quality audits, General follow-up of compliance to software development project schedules and budgets, General follow-up of provision of quality maintenance services to external and internal customers, In order to promote quality and resolve SQA system difficulties it requires −, Presentation for final approval of the proposed annual activities program and budget, Presentation for final approval of planned SQA adaptation projects together with the corresponding budgets, Initiation and leadership of periodic management review meetings dedicated to the organization’s software quality, Initiation of management-level discussions dedicated to special software quality events, such as severe quality failures, threats to the successful completion of projects due to severe professional staff shortages, managerial crises in the SQA unit, and so on, Middle management’s quality assurance responsibilities include −, Management of the software quality management system (quality system-related tasks), Management of tasks related to the projects and services performed by units or teams under the specific manager’s authority (project-related tasks), These include SQA activities to be performed on the department level −, Preparation of the department’s annual SQA activities program and budget, based on the recommended program prepared by the SQA unit, Preparation of the department’s SQA systems development plans, based on the recommended plan prepared by the SQA unit, Control of performance of the department’s annual SQA activities program and development projects, Presentation of the department’s SQA issues to top management, These vary according to the organization’s procedures and distribution of authority; they usually involve −, Control of compliance to quality assurance procedures in the department’s units, including CAB, SCM and SCCA bodies, Detailed follow-up of contract review results and proposal approvals, Review of unit performance of planned review activities; approval of project documents and project phase completion, Follow-up of software tests and test results; approval of project’s software products, Follow-up of progress of software development project schedules and budget deviations, Advice and support to project managers in resolving schedule, budget and customer relations difficulties, Follow-up of quality of maintenance services provision, Detailed follow-up of the project risks and their solutions, Follow-up of project’s compliance with customer requirements and customer’s satisfaction, Approval of large software change orders and significant deviations from project specifications. Data that is collected for measurement purpose is of two types −. − Data can be considered as consistent, if it doesn’t show a major difference from one measuring device to another. A clear understanding of goals can be used to generate suggested metrics for a given project in the context of a process maturity framework. Effort is expressed as a function of one or more variables such as the size of the program, the capability of the developers and the level of reuse. Ad hoc committees are established on a short-term per-problem basis, with members nominated by the executive responsible for software quality issues, the head of the SQA Unit, the SQA sub-units, permanent SQA committees, or any other body that initiated its formation and has an interest in the work.

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