Architecture Without an End State

`Architecture Without an End State` is a concept introduced by M. Nygard. It describes architecture as a mix of past decisions, the current state, and future vision. This means transitioning a system from one architecture to another isn't possible; instead, iterative steps must be taken toward current business goals. But business goals and requirements may change over time, and this series of changes is endless.

Nygard suggests 8 rules for designing systems that adapt to change:

✏️Embrace Plurality: Avoid creating a single source of truth. Each system should have its own entity model with its own related data. Different representations are connected through a system of global identifiers (URNs and URIs). Assume an open world that can be extended anytime: new entities will be added, new integrations will appear, and new consumers will start using the system.
✏️Contextualize Downstream: Upstream changes can affect all downstream systems. Minimize the impact by localizing the context (since business rules have different interpretations and requirements across business units) and reducing the number of entities that all systems need to know about.
✏️Beware Grandiosity: Avoid enterprise modeling attempts and global object model creation, as they are often too complex to be practical. Instead, narrow the scope and build a model for a particular problem or area. Start small and make incremental changes based on feedback.
✏️Decentralize: This allows to make local optimization of resources and budgets.
✏️Isolate Failure Domains: Use modularity to define proper system boundaries and isolate failures. Resilient architecture admits componentwise changes
✏️Data Outlives Applications: Data lives longer than technology and specific applications. Use a hexagonal architecture (ports & adapters) to separate business logic from data storage.
✏️Applications Outlive Integrations: Integrations with other systems will change over time. Build a hexagonal architecture so that all systems are connected via explicit boundaries, making communication a boundary problem rather than a domain layer problem.
✏️Increase Discoverability of Information: Poor information flow within an organization leads to duplicate system functions and reinventing the wheel between different teams. Improving information discovery reduces costs of development (fewer duplicates). Some ideas include internal blogs, open code repositories, and modern search engines.

The only true end state for a system is when the company shuts down and all services are turned off. Main recommendation from the author is to stop chasing the end state; it's not achievable. Continuous adaptation is the most effective way to build a system, and these rules can help guide that process.

#architecture #systemdesign