IBM SG24-7368-00 manual Viewpoint Expresses Concern

Table 2-2 Core SE RUP viewpoints

Viewpoint	Expresses	Concern
	Roles and responsibilities	Worker activities, human.system
Worker		interaction, human performance
	of system workers
		specification
	Logical decomposition of	￿ Adequate system functionality to realize
	the system as a coherent	use cases
Logical	set of SysML blocks that	￿ System extensibility and maintainability
	collaborate to provide the	￿ Internal reuse
	desired behavior	￿ Good cohesion and connectivity
	Distribution of the	Adequate system physical characteristics to
	physical elements that
Distribution		host functionality and meet supplementary
	can host the logical
		requirements
	services
	Information stored and	Sufficient system capacity to store data;
Information		sufficient system throughput to provide
	processed by the system
		timely data access
	Spatial relationships
Geometric	between physical	Manufacturability, accessibility
	systems
	Threads of control that	Sufficient partitioning of processing to
Process	carry out computational
		support concurrency and reliability needs
	elements

The set of viewpoints is fluid and has grown over time. Most development efforts do not require all of the viewpoints shown in Table 2-2.Further, viewpoints are extensible to address program domain specific needs, such as security or safety. Generally these extended viewpoints can reuse the semantics of the core set of viewpoints.

A particular viewpoint might not be useful at all model levels. For example, hardware developers are a category of (internal) program stakeholders concerned with the allocation of functionality and distribution of hardware within the system. However, at the analysis model level, decisions about where functionality will be implemented (in hardware, software, or workers) have not yet been made. As a result, there is typically no need for a hardware viewpoint at the analysis model level. However, if the system involves actual hardware development, then one certainly does need a hardware viewpoint at the more specific (lower) model levels.

Although different architectures require different sets of viewpoints, almost all require the logical and distribution viewpoints.

Chapter 2. Definitions, design points, and key concepts 27