Scenarios are the leaves Output: a characterization and prioritization of specific quality attribute requirements. High/Medium/Low importance for the success of the system High/Medium/Low difficulty to achieve (architect’s assessment)

To define a tangible quality attribute, a good starting point is to write a quality attribute scenario. A quality attribute scenario is an unambiguous way to specify a testable quality attribute. A quality attribute scenario is composed of six elements (as the following …

Artifact – what elements of the system are stimulated. 4.4 Quality Attribute Scenarios in Practice. General scenarios provide a framework for generating a large number of generic, system-independent, quality-attribute-specific scenarios. Each is potentially but not necessarily relevant to the system you are concerned with. To make the general scenarios useful for a particular system, you must make them Quality Attribute Scenarios [BCK03] • Stimulus • A condition that affects a system • Source of stimulus • The entity that generates the stimulus • Environment • The condition under which the stimulus occurred • Artifact • The artifact that was stimulated • Response • The activity that must result from the stimulus • Response measure • Quality attribute scenarios 1. Forming Quality attribute scenarios for Business and architectural qualities Scenarios for Business Quality 2. Projected lifetime of the system: Portion of scenario Possible values source End user, organization and developers 3.

It consists of six parts. Source of stimulus. This is some Quality Attribute Scenarios. Source of stimulus; Stimulus; Environment; Artifact; Response; Response measure. (see inside front cover). In the environment, the Concepts alignment. Software Architecture Contexts.

Qualities of the system. 2.

24 Mar 2017 Quality Attributes Scenario. Ø Is a quality-attribute-specific requirement. Ø It consists of six parts: • Source of stimulus. • Stimulus. • Environment.

Quality Attributes. Functionality and quality attributes are orthogonal.

Sadegh Aliakbary Software Architecture Course 13 The Trade-off Within complex systems: Quality attributes can never be achieved in isolation The achievement of any one will have an effect, (positive or negative) on the others E.g., almost every quality attribute negatively affects performance

QA Scenarios. That is, the abstract quality goal of modifiability must be made concrete. System- specific scenarios can be used to more clearly describe the quality attributes that Hence both these modifiability scenarios could be used to test the resulting design for ease of modification.

It is also a Since quality attributes are essential for a product and hence an important cost factor, architects and product management should cooperatively define the quality scenarios, derive the quality tree, and estimate the economic impact as well as the technical complexity of each quality attribute scenario (Bass et al., 2013). Qualities with high economic impact should have higher priorities than those with less economic impact.
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Most of these methods encourage the use of architectural patterns to develop architectures with known characteristics and apply scenarios to evaluate those architectures for desired quality attributes.

The Software Engineering Institute developed several evaluation methodologies, like Architecture Tradeoff Analysis Method (Clements, Kazman and Klein, 2002) that heavily build on scenarios to contrast and compare how the different quality attributes are met by candidate architectures. Quality attribute scenarios serve this purpose. For the same reason that use cases are essential in determining functional requirements, quality attribute scenarios are used to specify quality attribute requirements.
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Achieving Quality Attributes (II) The next step is to ﬁnd a solution to a Quality Attribute Scenario. To this, we have tactics. A tactic can be (but is not limited to) a design pattern, an architecture pattern, or an architectural strategy.

Qualities A quality attribute scenario is an unambiguous way to specify a testable quality attribute. A quality attribute scenario is composed of six elements (as the following Figure illustrates): Source of Stimulus: An entity capable of creating stimulus (internal or external people, a computer system, etc) 4.4 Quality Attribute Scenarios in Practice. General scenarios provide a framework for generating a large number of generic, system-independent, quality-attribute-specific scenarios. Each is potentially but not necessarily relevant to the system you are concerned with. To make the general scenarios useful for a particular system, you must make them system specific.