Architectural Decision Records (ADRs)
An Architectural Decision (AD) is a justified software design choice that addresses a functional or non-functional requirement that is architecturally significant. An Architecturally Significant Requirement (ASR) is a requirement that has a measurable effect on a software system’s architecture and quality. An Architectural Decision Record (ADR) captures a single AD and its rationale; the collection of ADRs created and maintained in a project constitute its decision log. All these are within the topic of Architectural Knowledge Management (AKM), but ADR usage can be extended to design and other decisions (“any decision record”).
The aim of the GitHub adr organization is to:
- Motivate the need for and benefits of AD capturing and establish a common vocabulary
- Strengthen the tooling around ADRs, in support of agile practices as well as iterative and incremental software engineering processes
- Provide pointers to public knowledge in the context of AKM and ADRs
The repository for the Website of the ADR organization is https://github.com/adr/adr.github.io.
ADRs in the Media
- Love Unrequited: The Story of Architecture, Agile, and How Architecture Decision Records Brought Them Together, Michael Keeling in the Pragmatic Designer column of IEEE Software Vol. 39 Issue 4 (2022) (PDF)
- Chapter 3 of “Patterns for API Design: Simplifying Integration with Loosely Coupled Message Exchanges” in the Addison Wesley Signature Series at Pearson features six narratives guiding through the conceptual level of API design: 29 recurring decisions with options and criteria. Learn more in this blog post.
- Architectural decision capturing is positioned as one of the essential activities in Design Practice Reference, a LeanPub e-Book.
- (German) Gut dokumentiert: Architecture Decision Records by @obfischer published at heise online.
Lightweight ADRs Should be Adopted
A “lightweight” ADR consists of title, status, context, decision, and consequences (according to @mtnygard). ThoughtWorks listed architectural decision records as “adopt” at their technology radar vol. 18: https://www.thoughtworks.com/en-us/radar/techniques/lightweight-architecture-decision-records.
We think that the considered options with their pros and cons are crucial to understand the reason of a chosen option. MADR — The Markdown Any/Architecture Decision Records (MADR:
[ˈmæɾɚ]) in this ADR organization includes such tradeoff analysis information.
Relation of ADRs, MADR, and Others
Sustainable Architectural Decisions
We base our work on the guidelines and principles in Sustainable Architectural Decisions by Zdun et al., for instance the Y-statement format suggested in that article. However, we are open to other formats of ADRs as shown at @joelparkerhenderson’s repository.
In short, the Y-statement is as follows:
In the context of
<use case/user story u>, facing
<concern c>we decided for
<option o>to achieve
<quality q>, accepting
The long form of it is as follows (extra section “because”):
In the context of
<use case/user story u>, facing
<concern c>we decided for
<option o>and neglected
<other options>, to achieve
<system qualities/desired consequences>, accepting
<downside d/undesired consequences>, because
You can find more explanations and examples on Medium Y-Statements - A Light Template for Architectural Decision Capturing.
A Definition of Done for Architectural Decision Making proposes five criteria and a checklist to decide when it is time to set the status of a single decision to “done”: evidence, criteria and alternatives, agreement, documentation, and realization/review plan. Here, we focus on the ‘D’ in ecADR.
Existing ADR Templates
- Overview: Architectural Decision Records: collection of markdown templates converted to Markdown
- MADR: The Markdown Architecture Decision Records (MADR:
[ˈmæɾɚ]). Lean ADRs to quickly document architectural decisions in code. - Slogan: architectural decisions that matter
- Comparison of seven templates: Architectural Decision Guidance Across Projects - Problem Space Modeling, Decision Backlog Management and Cloud Computing Knowledge. WICSA 2015: 85-94.
- Context, background and examples of good and bad justifications can be found in this blog post.
- DecisionCapture: Templates for agile projects and explanation of the ADR universe, with example.
- cards42 has adopted the Y-statement template in its German ADR card; the English version is similar, but adds state information.
- The template for ISO/IEC/IEEE 42010:2011, the international standard for architecture descriptions of systems and software, suggests nine information items for ADRs its Appendix A. It also identifies areas to consider when identifying key decisions.
Good ADRs (and how to get to them)
- How to create ADRs — and how not to collects good practices and anti patterns
- Architectural Significance Test and Some Core Decisions
- The Markdown ADR (MADR) Template Explained and Distilled
- Proposal for A Definition of Done for Architectural Decision Making
- How to review ADRs — and how not to has good practices, anti patterns, review check list
Decision Capturing Tools
Disclaimer: The following list is rather inclusive. Please find out about the status and the maturity of the list entries for yourself by following the links. We are happy to include more candidate assets here.
- adr-manager: Craft MADR 2.x templates directly in the Web Browser.
- adr-tools - bash scripts to manage ADRs in the Nygard format. example.
- adr-viewer - python application to generate a website from a set of ADRs.
- architectural-decision: PHP library to create ADRs using PHP8 Attributes.
- Embedded Architectural Decision Records, which shows how a distributed AD log can be embedded in Java Code via ADR annotations.
- Log4brains: CLI and web UI to log and publish your ADRs as a static website
- Loqbooq: Web App with Slack integration to record ADR-inspired decision logs
Tooling related to architecture management
- ArchUnit: unit tests for architecture
- docToolchain: docToolchain is an implementation of the docs-as-code approach for software architecture plus some additional automation.
- Structurizr: Structurizr is a collection of tooling to help you visualise, document and explore your software architecture using the C4 model.
Interesting, but unmaintained tooling
- adr-log: Generates a architectural decision log out of MADRs.
- ADMentor Architectural Decision Modeling Add-In for Sparx Enterprise Architect
- eadlsync: Synchronizes embedded architectural decision records with a repository of architectural decisions.
- SE Repo: Software Engineering Repository. A repository for versioning software engineering artifacts, which can be architectural decisions, patterns, and others.
- “An Adoption Model for Architectural Decision Making and Capturing”
- Architectural Decisions — The Making Of - provides some history on architecture decision records.
- Architectural Decision Records (ADR): Open & Transparent Decision History in the Open Practice Library
- An AWS Prescriptive Guidance recommends using architectural decision records to streamline technical decision-making for a software development project.
- Architectural Knowledge Management (AKM) overview at OST
- Documenting Architecture Decisions by Michael Nygard
- Architecture Decision Records in Action by Michael Keeling (IBM Watson Group) and Joe Runde (IBM) - presentation including empirical numbers.
- Documenting Architecture Decisions - Blog entry by Fabian Keller
- From Architectural Decisions to Design Decisions and ADR = Any Decision Record? - two blog posts by Olaf Zimmermann proposing to exted the scope of ADRs.
- Method selection and tailoring in DPR, the Design Practice Repository (DPR) on GitHub and the Design Practice Reference, a corresponding LeanPub e-Book. Architectural decision capturing is positioned as one of the essential activities in DPR.