Temporal JSON Schema Versioning in the τJSchema Framework

τJSchema is a framework for the management of temporal documents stored in JSON format in a NoSQL database, similar to the τXSchema framework proposed for XML. In this work, we extend τJSchema to temporal schema versioning support. The proposed approach provides a systematic solution to the challenging task of evolving a JSON schema while maintaining all schema versions with their corresponding instances and, thus, guarantees the bookkeeping of a full history of both data and schemas. All components of a temporal JSON schema (i.e., conventional schema, temporal logical and physical characteristics) are allowed to vary over time to reflect changes in the real world and, thus, in application requirements. To this end, four sets of primitives for changing JSON schema components and their related JSON instance documents are introduced. The feasibility of our approach and the usage of the proposed primitives have been shown through a detailed and illustrative example.