pairedservice

Pairedservice is a software design pattern where two microservices are paired to deliver a single business capability. The pair consists of a primary service and a companion service that cooperate to process requests and maintain domain boundaries.

In a pairedservice architecture, the two services communicate via a defined contract, typically using lightweight synchronous APIs or asynchronous messaging. A coordination channel aligns intent, timing, and data changes, and a correlation ID ties related actions.

Behavior: the primary handles core logic and delegates to the companion for ancillary tasks such as validation, auditing, or updates to external systems. If the companion fails, compensation or rollback mechanisms preserve consistency, often through eventual consistency.

Common patterns include the coordinating pair, where actions run in a short, ordered sequence; and the compensating pair, which undoes effects if a failure occurs. Some designs allow the companion to be hot-swapped for versioned deployments.

Use cases include financial transactions with audits, order processing that requires stock allocation, and user management where authentication and authorization are linked.

Benefits and challenges: clearer ownership and easier testing of components, but added complexity, latency, and the need for robust error handling, observability, and contract governance.

Implementation considerations: contract-first design, idempotent endpoints, correlation IDs, and explicit ownership rules; manage data duplication and data consistency policies; include monitoring and tracing across services.

Alternatives include the saga pattern for distributed transactions, two-phase commit for strong consistency, and API composition to orchestrate services without tight coupling.

In practice, pairedservice describes pairing two services to share responsibility for a business capability, offering modularity with a predictable integration surface.