Protokollis

Protokollis is a formalism used for describing and analyzing communication protocols. It provides a compact framework to model who communicates, what messages are exchanged, and under which conditions. The approach emphasizes modularity, enabling the specification of individual agents, message schemas, and communication channels, as well as the sequencing and coordination between components.

In Protokollis, core concepts include agents (or roles), states, events, and transitions. Messages carry typed payloads and may be constrained by envelopes, types, or schemas. Transitions are labeled with events and may include guards and actions that execute when a transition occurs. The language supports both synchronous and asynchronous communication, various channel reliability assumptions, and optional timing constraints. It also accommodates fault models and recovery paths, allowing the specification to express error handling and resilience strategies.

Semantics in Protokollis are typically given through labeled transition systems or trace-based interpretations. This enables formal analysis such as verification of safety properties (nothing bad happens), liveness properties (something good eventually happens), and deadlock freedom. Refinement relations permit the substitution of more detailed components for abstract ones, while preserving overall protocol behavior. Tooling in academic contexts often includes model checkers, simulators, and reference implementations used for teaching and research rather than as industry standards.

Applications of Protokollis include modeling classic handshake mechanisms, retransmission schemes, multi-party agreements, and fault-tolerant coordination patterns. By providing a readable yet expressive notation, it supports reasoning about interaction patterns, composing smaller protocols into larger systems, and comparing design choices. While primarily used in educational and research settings, Protokollis illustrates principles of protocol specification, verification, and formal reasoning.