Scenario-based architecture assessment

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The scenario-based architecture evaluation represents an approach to the evaluation of software architectures.

Viewing level

Scenario-based architecture evaluation methods approach the task of evaluating a software architecture , usually on a coarser level than architecture metrics. In contrast to software architecture metrics , which examine a software architecture on a fine-grained level, scenario-based approaches to architecture evaluation tend to work on a medium level of detail.

Action

Scenario-based architecture evaluation methods are often understood as a procedural model that leads to an architecture evaluation. The scenario-based methods provide more than just a calculation method or measurement instructions, they describe more or less detailed steps that lead to an architecture assessment. The most important steps in a scenario-based architecture assessment can be found in many of the different procedures:

  • Collection and prioritization of scenarios
  • Creation and description of the architecture (or the architectures to be compared, if this is the aim of the assessment)
  • Evaluation of the software architecture from the point of view of the most important scenarios surveyed
  • Present the results, prepare a report

Use of scenarios

In addition to these steps, the procedural models for scenario-based architecture assessment also have some techniques and concepts in common. The most important concept is the scenario.

In this context, a scenario is a brief description of a single interaction between a person affected or an interest group (e.g. customers, nursing staff, etc.) with an application.

A basic classification, which is used in the SAAM procedure, for example , divides the scenarios into:

  • Direct scenarios (scenarios that the system can execute with the current architecture without changes.)
  • Indirect scenarios (scenarios that the system can only execute after changes to the architecture. This category also includes the scenarios that serve to operationalize an uncertain future.)

Operationalization of quality features through scenarios

Scenario-based architecture assessment procedures use scenarios to specify exactly what the project participants consider quality characteristics such as B. Understand " changeability ". This approach makes it possible to operationalize quality attributes that are often only vaguely specified in requirements documents and can be interpreted in different ways. According to this, scenarios can be assigned to the various quality characteristics that they specify. The scenarios can also be understood as test cases for the architecture evaluation. Just as the quality of a software test depends on the test plan, the quality of the evaluation result achieved with such a method depends crucially on the quality of the scenarios surveyed. The scenarios must map the current and future requirements of the application as comprehensively as possible. No important and probable scenario should be missing. Therefore, the choice of people who will take part in the assessment is important. The views of important project participants must be represented accordingly.

Evaluation of the scenarios

The techniques used to evaluate each scenario depend on the type of scenario and the objective of the evaluation. Often with direct scenarios the object of consideration is how the architecture executes a scenario. In the case of indirect scenarios, the focus is more on the changes that have to be made to the architecture in order to execute the scenarios. The question of the extent to which a software architecture to be evaluated fulfills certain quality requirements or involves risks with regard to these quality requirements can be addressed by a scenario-based method through a qualitative (e.g. description of risk points in the architecture) or quantitative (e.g. estimation of the effort for future changes in person days) answer the investigation.

Additional benefit from the evaluation

In addition to the scenario assessments mentioned above, a scenario-based architecture assessment also produces a more precise description of the qualitative requirements for the system under consideration via the scenarios. The architecture description can also be further improved within the scope of such an evaluation method. Another benefit of a scenario-based architecture assessment is:

  • in the meetings that are part of many scenario-based procedures; these promote communication between those involved in the project;
  • in an improved understanding of software architecture;
  • in one way to improve the architecture development process

Procedure

Several methods use this approach:

  • SAAM software architecture analysis method
  • ATAM Architecture tradeoff analysis method:
  • ACDM Architecture-centric design method

See also

literature

  • Rick Kazman 1996: Scenario-Based Analysis of Software Architecture
  • Rick Kazman: Toward a Discipline of Scenario-based Architectural Engineering
  • Paulo Merson 2009: Data Model as an Architectural View

Individual evidence

  1. ^ Architecture Tradeoff Analysis Method . Carnegie Mellon Software Engineering Institute. Retrieved January 14, 2013.
  2. Lattanze, Anthony J. (2009). Architecting Software Intensive Systems: A Practitioners Guide. Software engineering. CRC Press. ISBN 978-1-4200-4569-7 .