The four different types of software maintenance are each performed for different reasons and purposes. A given piece of software may have to undergo one, two, or all types of maintenance throughout its lifespan. Corrective software maintenance is the typical, classic form of maintenance for software and anything else for that matter. Corrective software maintenance is necessary when something goes wrong in a piece of software including faults and errors.
These can have a widespread impact on the functionality of the software in general and therefore must be addressed as quickly as possible. Many times, software vendors can address issues that require corrective maintenance due to bug reports that users send in. If a company can recognize and take care of faults before users discover them, this is an added advantage that will make your company seem more reputable and reliable no one likes an error message after all.
Preventative software maintenance is looking into the future so that your software can keep working as desired for as long as possible. This includes making necessary changes, upgrades, adaptations and more. Preventative software maintenance may address small issues which at the given time may lack significance but may turn into larger problems in the future.
As with any product on the market, once the software is released to the public, new issues and ideas come to the surface. Users may see the need for new features or requirements that they would like to see in the software to make it the best tool available for their needs. This is when perfective software maintenance comes into play. Perfective software maintenance aims to adjust software by adding new features as necessary and removing features that are irrelevant or not effective in the given software.
This process keeps software relevant as the market, and user needs, change. Adaptive software maintenance has to do with the changing technologies as well as policies and rules regarding your software. These include operating system changes, cloud storage, hardware, etc. When these changes are performed, your software must adapt in order to properly meet new requirements and continue to run well.
The software maintenance process involves various software maintenance techniques that can change according to the type of maintenance and the software maintenance plan in place. This can be user-generated or identified by the software developer itself depending on the situation and specific fault.
Analysis — The process of analyzing the suggested modification including understanding the potential effects of such a change. This step typically includes cost analysis to understand if the change is financially worthwhile. Design — Designing the new changes using requirement specifications 4. Implementation — The process of implementing the new modules by programmers. System Testing — Before being launched, the software and system must be tested.
It also groups together the corrective and preventive maintenance categories into a correction category, as shown in Table 5. A number of key issues must be dealt with to ensure the effective maintenance of software.
Software maintenance provides unique technical and management challenges for software engineers—for example, trying to find a fault in software containing a large number of lines of code that another software engineer developed. Similarly, competing with software developers for resources is a constant battle. Planning for a future release, which often includes coding the next release while sending out emergency patches for the current release, also creates a challenge.
The following section presents some of the technical and management issues related to software maintenance. They have been grouped under the following topic headings:. Limited understanding refers to how quickly a software engineer can understand where to make a change or correction in software that he or she did not develop.
Research indicates that about half of the total maintenance effort is devoted to understanding the software to be modified. Thus, the topic of software comprehension is of great interest to software engineers. Thus, software engineers may initially have a limited understanding of the software; much has to be done to remedy this. The cost of repeating full testing on a major piece of software is significant in terms of time and money.
In order to ensure that the requested problem reports are valid, the maintainer should replicate or verify problems by running the appropriate tests.
Regression testing the selective retesting of software or a component to verify that the modifications have not caused unintended effects is an important testing concept in maintenance. Additionally, finding time to test is often difficult. Coordinating tests when different members of the maintenance team are working on different problems at the same time remains a challenge.
When software performs critical functions, it may be difficult to bring it offline to test. Tests cannot be executed in the most meaningful place—the production system. The Software Testing KA provides additional information and references on this matter in its subtopic on regression testing. Impact analysis describes how to conduct, costeffectively, a complete analysis of the impact of a change in existing software. They use that knowledge to perform impact analysis, which identifies all systems and software products affected by a software change request and develops an estimate of the resources needed to accomplish the change.
Additionally, the risk of making the change is determined. The change request, sometimes called a modification request MR and often called a problem report PR , must first be analyzed and translated into software terms. Impact analysis is performed after a change request enters the software configuration management process. IEEE states the impact analysis tasks:. The severity of a problem is often used to decide how and when it will be fixed.
The software engineer then identifies the affected components. Several potential solutions are provided, followed by a recommendation as to the best course of action. Software designed with maintainability in mind greatly facilitates impact analysis.
Modifications may include corrections, improvements, or adaptation of the software to changes in environment as well as changes in requirements and functional specifications. As a primary software quality characteristic, maintainability should be specified, reviewed, and controlled during software development activities in order to reduce maintenance costs.
Maintainability is often difficult to achieve because the subcharacteristics are often not an important focus during the process of software development.
This in turn can, and often does, result in a lack of software documentation and test environments, which is a leading cause of difficulties in program comprehension and subsequent impact analysis. The presence of systematic and mature processes, techniques, and tools helps to enhance the maintainability of software. Organizational objectives describe how to demonstrate the return on investment of software maintenance activities. Initial software development is usually project-based, with a defined time scale and budget.
The main emphasis is to deliver a product that meets user needs on time and within budget. In contrast, software maintenance often has the objective of extending the life of software for as long as possible. In addition, it may be driven by the need to meet user demand for software updates and enhancements. In both cases, the return on investment is much less clear, so that the view at the senior management level is often that of a major activity consuming significant resources with no clear quantifiable benefit for the organization.
Staffing refers to how to attract and keep software maintenance staff. Maintenance is not often viewed as glamorous work. The software life cycle process is a set of activities, methods, practices, and transformations that people use to develop and maintain software and its associated products. At the process level, software maintenance activities share much in common with software development for example, software configuration management is a crucial activity in both.
Maintenance also requires several activities that are not found in software development see section 3. These activities present challenges to management. The team that develops the software is not necessarily assigned to maintain the software once it is operational. In deciding where the software maintenance function will be located, software engineering organizations may, for example, stay with the original developer or go to a permanent maintenance- specific team or maintainer.
Having a permanent maintenance team has many benefits:. Since there are many pros and cons to each option, the decision should be made on a case-bycase basis. Outsourcing and offshoring software maintenance has become a major industry. Organizations are outsourcing entire portfolios of software, including software maintenance.
More often, the outsourcing option is selected for less mission-critical software, as organizations are unwilling to lose control of the software used in their core business.
One of the major challenges for outsourcers is to determine the scope of the maintenance services required, the terms of a service- level agreement, and the contractual details. Outsourcers will need to invest in a maintenance infrastructure, and the help desk at the remote site should be staffed with native-language speakers.
Outsourcing requires a significant initial investment and the setup of a maintenance process that will require automation. Software engineers must understand the different categories of software maintenance, discussed above, in order to address the question of estimating the cost of software maintenance. For planning purposes, cost estimation is an important aspect of planning for software maintenance. Section 2. Maintenance cost estimates are affected by many technical and nontechnical factors.
A combination of these two can also be used. Parametric cost modeling mathematical models has been applied to software maintenance. Of significance is that historical data from past maintenance are needed in order to use and calibrate the mathematical models. Cost driver attributes affect the estimates. Experience, in the form of expert judgment, is often used to estimate maintenance effort.
Clearly, the best approach to maintenance estimation is to combine historical data and experience. The cost to conduct a modification in terms of number of people and amount of time is then derived. Maintenance estimation historical data should be provided as a result of a measurement program. There are several software measures that can be derived from the attributes of the software, the maintenance process, and personnel, including size, complexity, quality, understandability, maintainability, and effort.
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