Software Maintainance

Summary

This lecture explores the essential aspects of software maintenance, emphasizing the importance of modifying programs post-deployment. It covers the different types of maintenance, including fault repairs, environmental adaptations, and functionality additions. The lecture highlights the higher costs of maintenance compared to development, challenges in modifying legacy systems, and the need for maintenance prediction. It also discusses software re-engineering and refactoring as crucial processes for enhancing system maintainability. The role of complexity in maintenance, alongside re-engineering to reduce risk and cost, is also examined in detail.

Takeaways

• 😀 Software maintenance refers to modifying a program after it has been deployed to fix bugs, adapt to new environments, or add new features.
• 🛠️ The maintenance phase starts after the software is released and is operational, either in the market or for a client.
• 🔄 There are two main types of software: custom software, developed for specific clients, and generic software, which evolves to serve a broad user base.
• ⚙️ Software maintenance can be categorized into three main types: fault repairs (bug fixes), environmental adaptation (system compatibility), and functionality additions (new features).
• 💸 Maintenance costs are typically much higher than development costs, often ranging from 2 to 100 times more, depending on the application and its complexity.
• ⏳ As software ages, maintenance becomes more costly due to factors like outdated technology, system degradation, and lack of documentation.
• 📉 The majority of maintenance work is spent adding new features (58-60%) and fixing faults (20-24%), with environmental adaptation making up the smallest portion (19%).
• 🔍 Maintenance prediction involves analyzing which parts of the system are most likely to need changes and estimating their future costs.
• 🔄 Re-engineering is used to restructure or rewrite parts of an old system without changing its functionality, reducing risk and often being more cost-effective than building new software.
• 🔧 Refactoring improves the internal structure of existing code to make it more efficient and easier to maintain, serving as a form of preventative maintenance.
• 📝 A tight coupling of system components can make changes more difficult, while loosely coupled components are easier to maintain and modify.

Q & A

What is software maintenance?

Software maintenance refers to the modification of a program after it has been put into use, which typically starts after the software has been deployed or released. It involves updates, bug fixes, and adapting the software to changing environments or requirements.

What are the two main categories of software?

The two main categories of software are generic software and customized software. Generic software is designed for broad user bases, while customized software is developed specifically to meet the needs of a particular client or user.

What are the three main types of software maintenance?

The three main types of software maintenance are fault repairs, environmental adaptation, and functionality addition/modification. Fault repairs fix bugs or deficiencies, environmental adaptation ensures the software runs in different environments, and functionality addition involves adding new features to meet new requirements.

How does maintenance cost compare to development cost?

Maintenance costs are typically higher than development costs, often ranging from two to a hundred times more, depending on the application. This is due to the need to analyze and modify existing systems, which is more complex than initial development.

Why is maintaining aging software more expensive?

Aging software becomes more difficult and expensive to maintain because its architecture may degrade over time, documentation may be incomplete or lost, and the code may no longer be compatible with newer technologies or environments.

What is the relationship between maintenance and the complexity of the system?

The complexity of a system directly impacts its maintenance. Highly complex systems with tightly coupled components or numerous interfaces require more effort for maintenance, especially when changes are made to the environment or business requirements.

What is software re-engineering, and why is it important in maintenance?

Software re-engineering involves restructuring or rewriting part or all of a legacy system to improve its maintainability without changing its functionality. It helps reduce risks, costs, and improves long-term maintainability, especially for systems with frequent updates.

What is refactoring in software maintenance?

Refactoring is the process of improving a program's structure, reducing its complexity, and making it easier to understand without adding new functionality. It is considered preventative maintenance to prevent future issues and improve code quality over time.

What are some common 'bad smells' in program code that can be improved through refactoring?

Common 'bad smells' include duplicate code, long methods, switch-case statements, data clumps, and speculative generality. These issues can be addressed through refactoring techniques such as removing duplicate code, breaking down long methods, and encapsulating data into objects.

How do business process changes affect software maintenance?

Changes in business processes, such as changes in policies or requirements, often lead to the need for software modifications. This can increase the number of maintenance requests, especially in systems like ERP where business processes are deeply integrated with the software.