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• Supportability: This involves designing the system to ensure that changes such as reconfiguring tables of values and adding new software features can be implemented easily over time. The former is called maintainability and the latter is called tutensibiliry. The degree to which this is necessary depends on where the system fits in the overall set of applications in an organization (which is called the application portfolio). For example, consider a system that will be used for into the future and that will likely need significant investments to extend its capabilities over time. Supportability requirements would be high for such a system. On the other hand, consider a system that will be used
by only a small number of users for another year, after which it will be replaced by another system. This system would have low supportability requirements.
Supportability
The degree to which a system needs to be easily reconfigured (maintainability) and easily updated with new features (supportability).
• Criticality: This general concept points to the cost of things going wrong—things like system downtime or security breaches. As the costs of failure rise, the value of BDUF to prevent failures increases. Several key subfactors include: o Mission criticality: If the organization can’t operate its core business without the application mining, then the application is mission critical. Examples could include an airline’s reservation system, a health insurer’s claims processing system, or a manufacturer’s logistics and supply chain management system. o Protecting sensitive/confidential data: Customer and financial data are common examples of this kind of data. Even more critical examples can be found, for example, in patient-identifiable health care data. o ” Facing the public Internet: The prior point is magnified when the application can be accessed via the internet (as opposed to only being accessible by employees within the firm’s secure intranet environment). o ” Having impacts on human safety: This is a major concern for systems that tend to fall outside the range of administrative and reporting systems we focus on in this book—for example, an airplane autopilot system, an autonomous driving system for a car, a power plant control system, or systems that control health care devices used to treat people (e.g., X-rays or anesthesia). However, some of the administrative systems that we discuss here may impact human safety, including systems that control building security sensors and systems that allocate health care supplies and drugs in clinics and hospitals (as is the case with the 12C2 pharmacy application). o ” Being subject to regulation or audit: Certain types of systems—for example, banking systems, some systems used in government, and so forth—must comply with formal risk and legal audit requirements. This can compel the software team to utilize BDUF and/or BRUF, simply because laws and regulations require it.
Criticality
The degree to which a system faces high costs for poor reliability, security, safety, or auditability.
• Integration: This refers to the need to integrate or interface our system with other application systems. As the number of other systems increases, so does the need to plan for that interaction via BDUF. Compounding that would be the need to support new kinds of technical interfaces. For example, an older system may not natively support modern methods of system interaction, such as web services. This may require BDUF to determine how to retrofit or upgrade the system to do so.