Skip to main content

Stage 2: The Graph (Information Flow)

Stage 2

"Before a robot can perceive, it must communicate. We build the nervous system before the eyes."

The Philosophy of Stage II​

In Stage I, we built the Substrate—the ability to execute code (Processes) and define math (Linear Algebra). In Stage II, we solve the Distributed State Problem.

A robot is not a single program. It is a distributed system of independent nodes—sensors, actuators, planners—that must agree on a shared reality in real-time. This agreement is mediated by The Graph.

Learning Objectives​

In this Deep Dive, you will master:

  1. The Distributed Mind: Understanding Nodes as independent cognitive units in a graph.
  2. The Pub/Sub Ontology: The physics of Middleware (DDS), Quality of Service (QoS), and Serialization.
  3. Service & Action Theory: Synchronous vs. Asynchronous patterns for robot behavior invocation.
  4. The Relativity of Space (TF2): Managing the geometric relationship between sensor frames and world frames using the Transform Tree.

Chapter Map​

  • 2.1 The Distributed Mind: Graph Theory & CAP Theorem.
  • 2.2 The Pub/Sub Ontology: Middleware & QoS.
  • 2.3 The Request/Response: Services & Actions.
  • 2.4 The Relativity of Space: TF2 & Transforms.

Prepare to abandon the idea of a "Main Loop". Welcome to the Event-Driven World.