Contracts

📄️ Introduction to Contracts

Blue contracts are the foundation of dynamic, event-driven behavior in Blue documents. While the Blue language itself provides structure and content addressing, contracts bring documents to life by defining how they respond to events and interact with the world.

📄️ Processing Checkpoints

Blue documents evolve as they process events, changing their state—and therefore their BlueId—while maintaining their fundamental identity. Processing checkpoints capture this temporal dimension, serving as formal markers in a document's ongoing journey.

📄️ Events from Multiple Sources

Blue documents often receive events from multiple channels. While each channel maintains its own ordering, a key challenge arises: how should events from different channels be sequenced relative to each other? This page explains how Blue handles this challenge through channel coordination contracts.

📄️ Source Binding

Blue documents can interact with events from the external world - from cryptocurrency transactions to weather conditions. This creates a powerful connection between digital documents and physical reality, but introduces an important question: how do we establish a shared understanding of external events?

📄️ Sequential Workflows

Sequential Workflows are the processing engines of Blue documents, defining how documents respond to events with a series of ordered steps. These workflows enable deterministic business logic that transforms static documents into dynamic, responsive entities.

📄️ Embedded Documents

Blue documents can embed other documents that have their own contracts and behaviors. This creates compositional structures where both parent and embedded documents process events independently while maintaining a consistent state. This page explains how to use these embedded documents and ensure they're properly processed.

📄️ Events

Events are the foundation of Blue document interactions—they flow into documents through channels, trigger workflows, and can be emitted by documents during processing. This page explains how events function within the Blue ecosystem and how documents can both react to and generate events.