  In Software Engineering, early detection of architectural issues is key. It
helps mitigate the risk of poor performance, and lowers the cost of repairing
these issues. Metrics give a quick overview of the project which helps
designers with the detection of flaws or degradation in their architecture.
Even though studies unveiled architectural metrics more than 25 years ago, they
have not yet been embraced by the industry nor the open source community. In
this study, we aim at conducting a review of existing metrics focused on the
software architecture for evaluating quality, early in the design flow and
throughout the project's lifetime. We also give guidelines of their usage and
study their relevance in different contexts.
