Software Requirements: The Requirements Set
Chapter Key Topics
The Internet Impact
The Internet opens doors for many new business opportunities. Each business community from one or multiple corporations is involved in producing a successful product through this medium. The implementation of an Internet solution involves capturing requirements from all the business communities. Organization of the requirements assists in identifying gaps and conflicts sooner in the process, when the cost of change is less.
This chapter introduces a requirements set framework that organizes individual requirements into specific categories. The purpose of this organization is to assist in the validation of requirement coverage for the problem domain, in this case, the Internet product. By arranging requirements in an organized fashion, gaps in knowledge and inconsistencies can be identified more readily and corrected earlier in the process. Organizing the requirements set according to the framework increases the speed with which products can be developed because its structure works with the evolutionary process and promotes parallelism.
While discussing the evolution of the requirements, different types of requirements emerged (see Figure 3.1). These are:
Figure 3.1 Requirement Types through Allocation
Initiating requirements: requirements that clarify the concept as it pertains to the business objective. These are typically the requirements identified by the sponsor of the business idea in the business case.
Primary requirements: business requirements that need to be satisfied in order to fulfill the concept. These are the requirements that each business community has identified as its scope in order to satisfy the business objective.
Derived requirements: requirements that need to be satisfied in order to satisfy the primary requirements. Derived requirements come in two types:
Supporting: requirements that have been allocated to a specific category because of their ability to supply essential details.
Association: requirements that have been written to support other requirements in a different category of the requirements set.
All of these types of requirements can be categorized and organized within the requirements set framework. All of them need the same components to create a high-quality requirement: identifier, description, priority, validation criteria, source, and so forth. The requirements set framework does not enforce the individual quality rules; it only categorizes the individual requirements of the requirements set into a specific organization. The category, and not the type of requirement, defines its placement in the requirements set framework.
A requirement category is the subject matter of the requirement. It takes three dimensions to properly categorize each individual requirement. These dimensions clarify the special interest of the subject matter and refer to the type of questions that need to be answered in order to define the specific needs for the category. These questions, when applied to the requirements set framework, create the requirements pattern.
The three dimensions are
- Community: corporate function
- Perspective: level of detail
- Focus: specialized view
A specific requirement is categorized before placing it into the requirements set framework (see Figure 3.2). The figure identifies a fourth category, association. This additional category is required to meld, link, or associate the different subject matter requirements together. To avoid confusion, this fundamental discussion appears later in the chapter. For now, let's review the different dimensions in closer detail.
Figure 3.2 Requirement Categorization
During the requirements process, each requirement is assigned (allocated) to different organizational areas that develop the requirement in order to satisfy the business objective. These different business communities correlate to the allocation process discussed in the previous chapter. The business objective of an Internet product is to develop a B2B product that will have the scope delivered to each of the business organizations. Each organization will identify a list of primary requirements to be incorporated into its own specific deliverables.
The communities are separated into four business areas (see Figure 3.3).
Figure 3.3 Requirement Community Category
Business practice: organizational divisions directly associated with the businesses that relate directly to the business objective. These include business areas such as product development, marketing, and customer service. For e-business, there may be multiple product objectives, one for each business in the B2B connection. In this scenario, a single goal for the product will have specific business objectives that correlate specifically to the company's purpose.
For example (see Figure 3.4), a book retailer has a B2B link with a ship and manage business practice community requirements. And, finally, each of the companies has its own requirements set. The links (association) between the requirements are additional requirements defined by both organizational communities. This will enable them to identify the impact of a change instituted by one corporation on the other.
Figure 3.4 Business-to-Business (B2B) Community Category Relationships
Business support: organizational divisions that support the running of the organization. These include human resources, finance, and legal. Their objective is to support the project by identifying requirements that need satisfying to meet the Internet product objectives. In a B2B scenario, the business support areas support their own company's interest. No cross-company correlation is necessary.
Business organization: divisions that dictate direction and business objectives, including the executive committee and the board of directors. Their objective is to support the Internet project by identifying requirements that need satisfying to meet the product objectives. As with business support, in a B2B scenario, the business organization areas support their own company's interest. They are instrumental in developing the vision for forming the relationship between B2B companies. It may be necessary to correlate these requirements across corporate requirements sets if one company requirement is dependent on the other.
Technology: divisions that relate only to the technological aspects of supporting the business objective. This does not include systems that developed as products to be sold. For example, Microsoft applications are products developed under the community business practice. These are external technology products. The sales-tracking systems, however, fall under the technology community. These are internal technology products. In a B2B situation, they are not only working to connect with different systems within their corporate boundaries but also are responsible for working jointly with other companies to develop the connection to the B2B company. A requirement could be dependent upon another requirement being satisfied by another company. The technology community may also need to develop derived requirements that will support the other company's primary requirements.
Just to make things more complicated, each of the first three communities receives requests to build technology products (external or internal). In fact, so too will the technology area (for example, system software/hardware upgrades). Each request needs to satisfy the needs of one, two, three, or all four of the communities.
Here, then, lies the definition of community. Community segments the types of deliverables according to business organization. Each deliverable is specific to meeting the needs of the business community. The needs (that is, requirements) will continue to evolve and be allocated further into the community (corporate to division to architectural to product levels) to build the deliverable for the business community. The evolutionary state within the business community can be correlated to perspective, discussed next.
Perspective relates to the evolution of the Internet product from idea to the implemented solution. Throughout the evolution of requirements, they will be further refined and specific details will be provided to enable the building of the solution. Through each step, a level of extraction takes place that eventually leads to the specific parts of the whole Internet product. A separate deliverable is produced for each perspective. Each deliverable takes a step toward building the product. Skipping an evolutionary step may provide a solution, but the solution will be flawed due to the missing detail or missing requirement. The solution will probably be delayed due to the need to go back and get the detail or requirement that should have been obtained earlier in the process. The final product is built but on incorrect information.
The idea phase (that is, initiating requirement) identifies the business community that has the primary interest in the product. The idea is then allocated to each community to develop the initial set of primary requirements (scoping and business requirements). Each community has its own perspective. Each perspective evolves the community's requirements through its specific allocation levels, developing essential details to the requirements and developing additional requirements (derived requirements) that are needed to support the idea. Different individuals are responsible for developing the requirements for the community and perspective. Each of these individuals has a specific point of view as to the categories of requirements that need to be captured. This specific point of view relates to the third requirements set category: requirement focus.
Focus looks at each perspective for the community from an abstract view of the product to be developed. For example, with respect to information systems, the focus would be the type of system component: interfaces, data, process, network, timing, rules, and constraints. The role of a specific community is to be responsible for creating an end deliverable. Through the evolution of requirements, the role has a specific, tailored view of the overall business idea. The person responsible for that focus develops a slice of the product that evolves through the same perspectives for the community as any other view.
For data focus,1 the list of entities evolves into an entity relationship. This high-level data model evolves into a fully attributed business model. This model is customized for the technical architecture which, in turn, is transformed into a data language that runs in production.
Relationships between Categories
To recap, community refers to the business unit, perspective relates to the level of abstract detail for the community, and focus pertains to the point of view of the community and perspective. The combination of community, perspective, and focus defines the category. The category is represented by a cell in the framework. Following a requirements process (and subprocess) fills the framework. To assist in filling the framework, the requirements pattern has questions that are tailored to the subject matter for each cell or category.