protokollpar

Protokollpar, or protocol pair, is a term used in computer science to refer to the two interacting protocols on opposite ends of a communication channel. It typically denotes a pair of components, often written as (P_A, P_B), where each component describes the permissible messages, states, and actions of one communicating party. The concept focuses on how the two sides coordinate to achieve correct interaction.

In formal modelling, a protokollpar can be represented by two finite-state machines or labeled transition systems that synchronize on shared messages. This allows analysis of compatibility, correctness, and interaction properties such as deadlock freedom, safety, and liveness when the two sides operate together. The notion supports both synchronous and asynchronous communication, and it highlights sequencing constraints, error handling, and recovery procedures.

Applications of the protokollpar concept include protocol design, negotiation, and verification. In security and formal methods, examining a protokollpar helps determine whether the sequence of messages preserves intended security properties, such as authenticity and integrity, under the assumptions of each party’s specification.

Examples often cited include client-server handshakes, where the client’s protocol defines requests and state transitions and the server’s protocol defines corresponding responses and state transitions. More complex scenarios may extend to multi-party interactions, where a single two-party protokollpar is insufficient and higher-order models are required.

Remark: The term is more common in German-language literature; in English, authors may refer to it as a protocol pair or describe the two sides as the components of a two-party protocol specification.