A business analyst typically leverages best practice templates, frameworks, and catalogues during this phase. Questions will be asked about each type of non-functional requirement and are done using a questionnaire for NFRs; for example, usability, scalability, performance, availability, stability, extensibility, and so on.
The NFR life cycle processes results in the improvement of a service performance for non-functional requirements. Standards and best practice specifications are a key part of these phases. Standards bodies provide documented best practice artifacts that can be re-used for various phases of the NFR life cycle.
Architecting non-functional requirements consists of the evaluation and selection of a set of architecture building blocks and technology patterns that will implement specific non-functional requirements. This process also includes refining and decomposing (slicing and dicing) non-functional requirements and mapping non-functional requirements to technology building blocks.
Each non-functional requirement will have sub-qualities and metrics associated with each sub-quality. The performance of software quality against the quality targets is monitored and analyzed through the Enterprise Monitoring and Management (EMM) capabilities.
EMM is also known as application performance management (APM) and is discussed later in this book. EMM tools provide support for business monitoring and reporting. Measurable metrics for the service qualities or NFRs are key for non-functional requirements monitoring.
Non-functional requirements may be performance targets for organizational metrics. For example, Mean Time to Restore Service (MTTRS) is a key metric for service availability and recoverability. For example, the percent of time the 30 minutes MTTRS is met or exceeded for e-mail becomes a measurable non-functional requirement metric for e-mail services.
Several organizations treat availability, continuity, and security as the most critical non-functional requirements, and classify them as such. The remaining non-functional requirements dimensions are important but treated as secondary when compared to availability, continuity, and security. The prioritization scheme may vary from one industry to another and one organization to another.
As a case in point, an online brokerage firm competing on the basis of cost and value to its customer can treat service efficiency, especially from a cost structure perspective, as critical to the firm's strategy and competitive advantage. As such, efficiency becomes a key non-functional requirements dimension both for domain architectures and service architectures. In fact, the online brokerage firm's IT department has a dedicated and collaborative process to constantly look for cost-cutting opportunities and to implement them faster than its competition. This enterprise was among the first in the industry to replace several of its high-end UNIX systems with low-end Linux systems in the 1990s. The penetration of low-cost Linux systems in the firm's data centers is also the in the industry. An enterprise's business and IT strategy, business model, and industry and regulatory environments are some of the factors that determine the prioritization scheme.
