Software maintenance

Modification of a software product after delivery
(Learn how and when to remove this template message)
Part of a series on
Software development
Core activities
  • Processes
  • Requirements
  • Design
  • Construction
  • Engineering
  • Testing
  • Debugging
  • Deployment
  • Maintenance
Paradigms and models
  • Software engineering
  • Agile
  • Cleanroom
  • Incremental
  • Prototyping
  • Spiral
  • V model
  • Waterfall
Methodologies and frameworks
  • v
  • t
  • e

Software maintenance in software engineering is the modification of a software product after delivery to correct faults, to improve performance or other attributes.[1][2]

A common perception of maintenance is that it merely involves fixing defects. However, one study indicated that over 80% of maintenance effort is used for non-corrective actions.[3] This perception is perpetuated by users submitting problem reports that in reality are functionality enhancements to the system.[citation needed] More recent studies put the bug-fixing proportion closer to 21%.[4]

History

Software maintenance and evolution of systems was first addressed by Meir M. Lehman in 1969. Over a period of twenty years, his research led to the formulation of Lehman's Laws (Lehman 1997). Key findings of his research conclude that maintenance is really evolutionary development and that maintenance decisions are aided by understanding what happens to systems (and software) over time. Lehman demonstrated that systems continue to evolve over time. As they evolve, they grow more complex unless some action such as code refactoring is taken to reduce the complexity. In the late 1970s, a famous and widely cited survey study by Lientz and Swanson, exposed the very high fraction of life-cycle costs that were being expended on maintenance.

The survey showed that around 75% of the maintenance effort was on the first two types, and error correction consumed about 21%. Many subsequent studies suggest a similar problem magnitude. Studies show that contribution of end users is crucial during the new requirement data gathering and analysis. This is the main cause of any problem during software evolution and maintenance. Software maintenance is important because it consumes a large part of the overall lifecycle costs and also the inability to change software quickly and reliably means that business opportunities are lost. [5] [6] [7]

Importance of software maintenance

The key software maintenance issues are managerial and technical. Management issues include alignment with customer priorities, staffing, assigning responsibilities, and estimating costs. Technical issues include: limited understanding, impact analysis, testing, and maintainability measurement.

Software maintenance is a broad activity that includes error correction, enhancements of capabilities, removal of obsolete capabilities, and optimization. Because change is inevitable, mechanisms must be developed for evaluation, controlling and making modifications.

Any work done on software after it is deployed is considered maintenance. Maintenance preserves software's value over time. Value can be enhanced by expanding the customer base, meeting new and additional requirements, becoming easier to use, more efficient and employing newer technology. Maintenance may span decades, whereas initial development is typically less than 3 years.

Software maintenance planning

An integral part of software is maintenance, which requires an accurate maintenance plan to be constructed during the software development. It should specify how users will request modifications or report problems. The budget should include resource and cost estimates, and a new decision should be addressed for the development of every new system feature and its quality objectives. The software maintenance, which can last for 5+ years (or even decades) after the development process, calls for an effective plan which can address the scope of software maintenance, the tailoring of the post delivery/deployment process, the designation of who will provide maintenance, and an estimate of the life-cycle costs.

Software maintenance processes

This section describes the six software maintenance processes as:

  1. Implementation - software preparation and transition activities, such as the creation of the maintenance plan; the preparation for handling problems identified during development; and the follow-up on product configuration management.
  2. Problem and modification analysis - Requests and problems are confirmed (reproduced), analyzed and investigated. Solutions are proposed and documented. Authorization to apply modifications is obtained.
  3. Modification implementation - software code, data and/or configuration is updated, compiled, and re-deployed.
  4. Modification acceptance - the individual who submitted the request operates/tests the software to confirm that the issue has been resolved.
  5. Migration (platform migration, for example) is exceptional, and is not part of daily maintenance tasks. If the software must be ported to another platform without any change in functionality, this process will be used and a maintenance project team is likely to be assigned to this task.
  6. Retirement of obsolete/replaced software components. This, typically does not occur on a daily basis.

There are a number of processes, activities, and practices that are unique to maintainers, for example:

Categories of software maintenance

E.B. Swanson initially identified three categories of maintenance: corrective, adaptive, and perfective.[8] The IEEE 1219 standard was superseded in June 2010 by P14764.[9] These have since been updated and ISO/IEC 14764 presents:

There is also a notion of pre-delivery/pre-release maintenance which is all the good things you do to lower the total cost of ownership of the software. Things like compliance with coding standards that includes software maintainability goals. The management of coupling and cohesion of the software. The attainment of software supportability goals (SAE JA1004, JA1005 and JA1006 for example). Some academic institutions[who?] are carrying out research to quantify the cost to ongoing software maintenance due to the lack of resources such as design documents and system/software comprehension training and resources (multiply costs by approx. 1.5-2.0 where there is no design data available).

Maintenance factors

Impact of key adjustment factors on maintenance (sorted in order of maximum positive impact)

Maintenance Factors Plus Range
Maintenance specialists 35%
High staff experience 34%
Table-driven variables and data 33%
Low complexity of base code 32%
Y2K and special search engines 30%
Code restructuring tools 29%
Re-engineering tools 27%
High level programming languages 25%
Reverse engineering tools 23%
Complexity analysis tools 20%
Defect tracking tools 20%
Y2K “mass update” specialists 20%
Automated change control tools 18%
Unpaid overtime 18%
Quality measurements 16%
Formal base code inspections 15%
Regression test libraries 15%
Excellent response time 12%
Annual training of > 10 days 12%
High management experience 12%
HELP desk automation 12%
No error prone modules 10%
On-line defect reporting 10%
Productivity measurements 8%
Excellent ease of use 7%
User satisfaction measurements 5%
High team morale 5%
Sum 503%

Not only are error-prone modules troublesome, but they can degrade performance too. For example, very complex spaghetti code is quite difficult to maintain safely. A very common situation which often degrades performance is lack of suitable maintenance tools, such as defect tracking software, change management software, and test library software. Below describe some of the factors and the range of impact on software maintenance.

Impact of key adjustment factors on maintenance (sorted in order of maximum negative impact)

Maintenance Factors Minus Range
Error prone modules -50%
Embedded variables and data -45%
Staff inexperience -40%
High code complexity -30%
No Y2K of special search engines -28%
Manual change control methods -27%
Low level programming languages -25%
No defect tracking tools -24%
No Y2K “mass update” specialists -22%
Poor ease of use -18%
No quality measurements -18%
No maintenance specialists -18%
Poor response time -16%
No code inspections -15%
No regression test libraries -15%
No help desk automation -15%
No on-line defect reporting -12%
Management inexperience -15%
No code restructuring tools -10%
No annual training -10%
No reengineering tools -10%
No reverse-engineering tools -10%
No complexity analysis tools -10%
No productivity measurements -7%
Poor team morale -6%
No user satisfaction measurements -4%
No unpaid overtime 0%
Sum -500%

[10]

Maintenance debt

In a paper for the 27th International Conference on Software Quality Management in 2019,[11] John Estdale introduced the term “maintenance debt” for maintenance needs generated by an implementation’s dependence on external IT factors such as libraries, platforms and tools, that have become obsolescent.[12] The application continues to run, and the IT department forgets this theoretical liability, focussing on more urgent requirements and problems elsewhere. Such debt accumulates over time, silently eating away at the value of the software asset. Eventually something happens that makes system change unavoidable.

The owner may then discover that the system can no longer be modified – it is literally unmaintainable. Less dramatically, it may take too long, or cost too much, for maintenance to solve the business problem, and an alternative solution must be found. The software has suddenly crashed to £0 value.

Estdale defines "Maintenance Debt"[12] as: the gap between the current implementation state of an application and the ideal, using only functionality of external components that is fully maintained and supported. This debt is often hidden or not recognized. An application’s overall maintainability is dependent on the continuing obtainability of components of all sorts from other suppliers, including:

and of course

The complete disappearance of a component could make the application un-rebuildable, or imminently unmaintainable.

See also

References

[13]

  1. ^ "ISO/IEC 14764:2006 Software Engineering — Software Life Cycle Processes — Maintenance". Iso.org. 2011-12-17. Retrieved 2013-12-02.
  2. ^ Soleimani Neysiani, Behzad; Babamir, Seyed Morteza; Aritsugi, Masayoshi (2020-10-01). "Efficient feature extraction model for validation performance improvement of duplicate bug report detection in software bug triage systems". Information and Software Technology. 126: 106344. doi:10.1016/j.infsof.2020.106344. S2CID 219733047.
  3. ^ Pigoski, Thomas M., 1997: Practical software maintenance: Best practices for managing your software investment. Wiley Computer Pub. (New York)
  4. ^ Eick, S., Graves, T., Karr, A., Marron, J., and Mockus, A. 2001. Does Code Decay? Assessing Evidence from Change Management Data. IEEE Transactions on Software Engineering. 27(1) 1-12.
  5. ^ Lientz B., Swanson E., 1980: Software Maintenance Management. Addison Wesley, Reading, MA
  6. ^ Lehman M. M., 1980: Program, Life-Cycles and the Laws of Software Evolution. In Proceedings of IEEE, 68, 9,1060-1076
  7. ^ Penny Grubb, Armstrong A. Takang, 2003: Software Maintenance: Concepts and Practice. World Scientific Publishing Company
  8. ^ Lientz, B. P.; Swanson, E. B.; Tompkins, G. E. (June 1978). "E. Burt Swanson, The dimensions of maintenance. Proceedings of the 2nd international conference on Software engineering, San Francisco, 1976, pp 492 — 497". Communications of the ACM. Portal.acm.org. 21 (6): 466–471. doi:10.1145/359511.359522. S2CID 14950091. Retrieved 2013-12-02.
  9. ^ Status of 1219-1998 by IEEE Standards
  10. ^ "The Economics Of Software Maintenance In The Twenty First Century" (PDF). Archived from the original (PDF) on 2015-03-19. Retrieved 2013-12-02.
  11. ^ Khan, O; Marchbank, P; Georgiadou, E; Linecar, P; Ross, M; Staples, G (2019). Proc of Software Quality Management XXVII: International Experiences and Initiatives in IT Quality Management. Southampton: Solent University. ISBN 978-1-9996549-2-4.
  12. ^ a b Estdale, John. Delaying Maintenance Can Prove Fatal. in [11]. pp. 95–106.
  13. ^ Pigoski, Thomas. "Chapter 6: Software Maintenance" (PDF). SWEBOK. IEEE. Retrieved 5 November 2012.

Further reading

External links

  • v
  • t
  • e
Note: This template roughly follows the 2012 ACM Computing Classification System.
Hardware
Computer Retro.svg
Computer systems organization
Networks
Software organization
Software notations and tools
Software development
Theory of computation
Algorithms
Mathematics of computing
Information systems
Security
Human–computer interaction
Concurrency
Artificial intelligence
Machine learning
Graphics
Applied computing
  • Category
  • Outline
  • WikiProject
  • Commons
  • v
  • t
  • e
Fields
Concepts
Orientations
Models
Developmental
Other
Languages
Related fields
  • Commons
  • Category
  • v
  • t
  • e
Current
802 series
802.1
802.3
802.11
Proposed
Superseded
See also
IEEE Standards Association
Category:IEEE standards
  • v
  • t
  • e
ISO standards by standard number
1–9999
10000–19999
20000–29999
30000+
  • Category
Authority control: National libraries Edit this at Wikidata
  • France (data)
  • Germany
  • Israel
  • United States