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Software Architecture Guide

Installability

Explanation

Section titled “Explanation”

Installability is a quality attribute. It asks: can people put this product into a given environment, and take it out again, successfully?

The standard defines it as the degree of effectiveness and efficiency of installing and/or uninstalling a product in a specified environment. Two words matter here:

  • Effectiveness: the install or uninstall actually works.
  • Efficiency: it works without wasting effort.

The phrase “specified environment” matters too. Installability is always judged for a stated target, such as a particular kind of machine or setup.

Where it sits in the quality model

In the 2023 wording shown on iso25000.com, installability is a sub-characteristic of Flexibility. Flexibility means the degree to which a product can adapt to changes in its requirements, contexts of use or system environment. (See the articles Flexibility and ISO/IEC 25010:2023 Product Quality Model Revision.)

Its siblings under Flexibility

  • Adaptability: adapting or transferring a product to different hardware or environments.
  • Scalability: handling growing or shrinking workloads by adapting capacity.
  • Replaceability: one product replacing another for the same purpose in the same environment.

Installability differs from these. It covers getting the product into place, and out again.

Example

Section titled “Example”

A team builds an internal reporting tool. The stated environment is “a standard office laptop.” The team writes down that installing and removing the tool must both succeed in that environment. Testers then try both on such a laptop and record whether each worked.

Trade-offs

Section titled “Trade-offs”

Qualities related to installability are not free. arc42 makes this point about replaceability: it reduces lock-in risk, but it is not free and rarely worth maximizing. The same view helps with installability. Decide how much is needed for the stated environment, and do not push it as far as possible.

Checks

Section titled “Checks”
  • The document names the specific environment in which installation and uninstallation must succeed.
  • Installability goals cover both installing and uninstalling, not installing alone.
  • Installability is placed under Flexibility, with the model version stated, and is kept distinct from adaptability, scalability and replaceability.
  • The document explains how much installability is needed and why, rather than aiming for the maximum.
Section titled “Related”

Sources

Section titled “Sources”