What to write in a architecture detail document?

You organization might have Technology Strategy, Technology Guidelines, Product standards, Product strategy. Each product or set of products might have architecture guidelines. You must ensure that your architecture is in line with those strategies and guidelines.

Architecture Concept Document(ACD)

According to the guidelines you prepare a document that represents all the concepts, the problem, the available solutions, the trade-offs and risks, the design of each solution, the execution plan etc. You can name it as Architecture Concept Document. It's a living document and should capture the current status of the software architecture.

Software Specification Document(SSD)

After you have taken the decision and defined the detail architecture, you create a Software Specification Document(SSD). And according to the SSD the development can start.

Constant Upgradation is needed

During development you will come across issues that will result in adapting and refining the Architecture Concept Document. Thus, the Architecture is only final before you release your product. Even after that, during the maintenance period you might do major changes or add functionality. This should result in a change in architecture. You need to capture this in the architecture, otherwise your architecture becomes obsolete over time. You could maintain the document with versions. The versions before release, the final release version and the versions after release. You can prepare a short document that describes only the architecture of the finalized version for the product in another document as a bluebook.

Preparing an ACD or SSD is not the end of work for an architect, he needs to help forming teams who will implement the architecture according to the work package. He needs to outline the dependencies between the work packages or teams. He can also help provide an effort estimate and identify the skills needed for implementation. He often needs to lead various Proof of Concepts(PoCs) needs to be done.

What information should you write in that document?

It should have an Executive Summary, a Preface section, an Overview section, an Introduction section, a Decision section. A section that addresses which components are being reused. How the software can be integrated with other software? How Security is ensured? How to Deploy, Migrate and Operation ? A Summary, few references and a Glossary.

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