Abstract: A dynamic schema service (DSS) stores and vends data schema for use by one or more client services. Each schema includes one or more data fields that describe related entities. The DSS also stores meta-schema, which defines limits for field definitions in the schema and other constraints. Using the DSS, a service owner defines fields and constraints unique to its business application and can revise those fields and constraints over time. When the client service requires a schema, the client service sends a request to the DSS, and the DSS responds with the current version of the schema for use by the client service. Service owners are able to edit their schemas in DSS, and the changes are immediately implemented in the corresponding services by virtue of the schema request to DSS. In some embodiments, the DSS employs a hierarchical graph structure to determine the requested schema.