Chapter 5: Bridges and Buses
Bridges of Necessity
In the late 1980s and early 1990s, as systems integration became a priority for businesses, we often relied on bridges—short-term solutions designed to connect incompatible systems. These bridges were essential but fragile, held together by the hope that they would be replaced by something more permanent.
I recall working on one such bridge for a banking integration project. The goal was to allow customers from an acquired bank to access their accounts through the parent bank’s systems. The solution was hurried but functional, enabling deposits and withdrawals across both institutions. It was never meant to last more than a year.
Unlike many bridges, this one didn’t linger. Integration into the host ESB happened and didn’t take years. For those integrations that do, the danger is that what was once a tactical solution can eventually become a ghost in the system—often with no owner or technical support.
The Elegance of Buses
The solution to ghost bridges came in the form of service buses. Unlike bridges, which are static and limited, buses are dynamic, designed to connect systems in a scalable, adaptable way. A service bus acts as a highway, facilitating communication between disparate components while allowing them to evolve independently.
The beauty of the service bus lies in its purity. It doesn’t impose logic on the systems it connects; it simply facilitates communication. This distinction is critical: the bus enables evolution without dictating terms.
Service buses are now ubiquitous. They carry millions of APIs connecting micro-services and functional objects to each other and are the neural network transport vehicles that efficiently support the evolution of connected nodes and the growth of network traffic.
Bridges vs. Buses: A Metaphor for Logic
The contrast between bridges and buses mirrors the evolution of logic itself.
- Bridges represent static logic—solutions tied to a specific context and unable to adapt as conditions change.
- Buses embody dynamic logic—frameworks designed to connect, evolve, and adapt over time.
Key Lessons from Bridges and Buses
1. Flexibility is Strength: Static solutions, like bridges, become liabilities over time. Dynamic systems, like buses, thrive because they adapt.
2. Connection Enables Evolution: The role of a bus is to connect evolving systems, not to enforce a single, unchanging framework.
3. Design for the Future: Systems should be built with the understanding that their context will change.
A service bus is a symbol of connection, adaptability, and evolution. Adding business logic would have turned it into yet another bridge, locking it into a specific context and undermining its purpose. A bus is a highway, made for transport at speed…it has no pedestrians.
A Universal Lesson
The story of bridges and buses isn’t just about technology—it’s about how we approach challenges in life. Do we build temporary solutions that solve today’s problems but create tomorrow’s constraints? Or do we design frameworks that allow for growth, change, and evolution?
In many ways, this is the essence of the Simple Theory of Logic over Time. Just as buses enable systems to adapt, so too must our logic. The future belongs to those who build for change.
Reflection
This chapter uses the metaphor of bridges and buses to explore the evolution of logic and systems design. It connects my technical experiences to broader lessons about adaptability and the importance of designing for impermanence.