Glossary

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Glossary / Evaluation and implementation guide

Event Contract

An event contract is a data contract applied to one specific event type, such as "lead.qualified" or "order.created". It defines that event's payload schema, required fields, value semantics, versioning rules, and delivery expectations.

It is narrower than a general data contract, which may cover tables, files, or API responses as well as events.

A practical example

Example: the "lead.qualified" contract specifies that the payload must include lead_id, qualified_at in UTC, and a source enum with three allowed values, and that renaming any field requires a new major version.

What to evaluate before investing

  • Check whether the tooling validates event payloads against the contract at send time.
  • Ask how a single event's version relates to the overall schema registry, if one exists.
  • Confirm the contract documents field semantics, not just structure, so consumers interpret values the same way.

Limitations and tradeoffs

Tradeoff: per-event contracts multiply documentation and governance work as event types grow, so teams often start with contracts only for critical events.

Plan your next step with MeshLine

Connect this decision to your automation, organic marketing and customer lifecycle management. In a MeshLine demo, discuss your existing tools, the scope you need and how to measure the result.