How can you minimize the impact of requirements changes on system architecture?

Well, let us start with the precept that there is never a good system architecture, it is usually the "least worst" architecture that you can build that can help with the Time-to-market challenge. I would also recommend that you have an overall vision of what you want to accomplish and keep the strategy flexible. Involve the customer in your vision and strategy discussions early, identify what aspects of your vision and strategy resonate with them and what they deem as value. Keep the pricing discussion out of the equation for the time being because the focus is to understand what is valuable. If you have identified the right set of outcomes, and vision, your system architecture design changes will be incremental not a paradigm change

Requirements changes are certain to happen in software development, but their impact on the system architecture can be significant. Some of the strategies to minimize the impact are - Structured change management process - Modular architecture, well defined interfaces and design for extensibility - Periodic reviews and audits - Documentation - Regular Automated Testing

Use Touché Ross Project Methodology…………… Refer to <Managing the Systems Development Process> book. Authors are Charles Biggs, Evan Birks, William Atkins.

Having that flexible and adoptable architecture framework with strong foundational pieces should help uphold the architecture while supporting ongoing and additional requirements. Key is to ensure that the initial architecture was built such to support such changes which does require some initial rigor on testing out the architecture with some foreseen changes that are yet un-articulated. Another key piece is extendability. Architecture evolves, extends and supports the ongoing needs of Product and its evolution alongside with the evolution of the market the product has to support. Critical stressing of the architecture upfront, experience and laying of the right foundation are all key to supporting ongoing change in requirements.

we can use Agile to minimize the requirement changes. Agile stories should have well defined acceptance criteria which lists all the positive and negative scenarios. If any new requirement comes up which is not in acceptance criteria we should create a new story and track it seperately.

Evaluating risks should be a big part of such reviews and evaluations. Always maintain a perspective on what the system is and not to its end users. There are certainly instances where users have alternate ways to solve their problems despite the solution offered by the product. Ensure product specs and warranties are included as part of system evaluations. Review system warranty policies - are all the components covered by respective warranty obligations? Are there vendors who can pick up the slack on those that are out of warranties Are the specs still relevant- there are cases where the system may be out of warranty but the spec is still relevant- meaning the market alternatives offer marginal improvements.

What I said in section 2 about business logic versus technical logic strikes many programmers as wrong - "it's all technical logic" is a familiar complaint. But the proper definition of a business rule is: "the logic that controls a change of state in persistent data." I.e., each decision that results in a change to data which is persisted is a business rule. Everything else is technical logic. The ideal expression of a business rule is in a non-procedural representation such as a decision table in a rules engine. Business rules expressed in a procedural language such as Java or C# are more likely to contain bugs, especially for extremely complex business rules. Very complex logic becomes impossible to comprehend in procedural code.

Probing and exploration is another way to go when requirements are unclear. Asking questions always opens a Pandora's box and it's good to note down what comes out of that box! Exploring multiple avenues (POCs) provides a wider understanding about how many ways a requirement can be interpreted. Broader and equally deeper understanding can lead to better decision making and in turn accommodating the required agility!

Keep It Stupid Simple A key factor in any design is the KISS principal - keep it simple. Thus modificstions are easier to br embedded. I would suggest get the view of the operational user as early stage of the initiatvr idea as possile as well