Software maintenance is an important part of the software development activity, but it is also the less discussed. As an example of its relative importance, you could just compare the space occupied by “software maintenance” and “test driven development” in Wikipedia (and I have nothing against TDD). Furthermore, software maintenance is a topic that is mostly discussed by university scholars and no practitioners. Have you ever heard of a software maintenance guru or agile software maintenance?
The main theory is that maintenance is “just” like software development on existing systems and does not need particular approaches or skill. Anyone who has spend time trying to understand an existing program or an architecture that has been twisted during some years knows that this activity is different from new projects.Our last poll wanted to know what percentage of your software development budget was devoted to maintenance. Maintenance is defined as the process of correcting, enhancing and optimising deployed software. Here are the answers:
25% or less of the budget ………..37%
26% to 50% of the budget …………27%
51% to 75% of the budget …………24%
more than 75% of the budget ………12%
Number of participants: 433
The annual maintenance costs in the US are estimated at over $ 70 billion. According to the different studies produced in the last century, maintenance should cost between 66% and 90% of the total life cycle costs. We can see in our survey that the majority of the participants estimate their maintenance budget below the 50% threshold. If we accept that these numbers are representative of a modified situation, many hypothesis can be made to explain it.
The adoption externally developed software (like ERP) for the large enterprise application has replaced the in-house development of the last century. Thus, a large part of the maintenance budget could be displaced to the licence area. This could also push the development teams of participating organisations to work on smaller applications, so there is less maintenance because this type of software is more easily replaced, especially in the Web world. The new technologies (Web, services) could also explain the lower level of maintenance spending. Many organisations are currently redeveloping applications to use these new technologies, freezing in the meantime the evolution and spending on existing software. The rapid evolution of Web technologies reduces the life expectancy of application and therefore the maintenance budget. Even if the backend remains unchanged, there has been a many evolutions / redevelopment from the initial static Web to the current Rich Interface Application trend. Finally, the outsourcing of maintenance activities to lower cost countries reduce proportion of the maintenance part in overall software development costs for organisation that locates new development in the US or Europe, where the majority of the Methods & Tools readers are.
Resources and numbers on maintenance:
Software Maintenance As Part of the Software Life Cycle
A Study in Software Maintenance
Software Maintenance and Evolution: a Roadmap