Basics: model, layers, endpoints

Every model belongs to one of three levels. The level decides which database holds the data and whether a person only sees their own rows.

At runtime a model exists as an entity (database), a DTO (response), a payload (input) and metadata (description). This page explains when each shape is in play and how data is mapped between them.

CDMS sets fields such as id, _createdOn, _userId, _MODELTYPE and _version itself. This page explains when each field is set and which of them the client may send.

Filter chain, REST layer, system layer, persistence, commit: what each station checks, what it decides and which error it stops with. Separately for reads and writes.

The fixed set of operations per model (create, read, update, delete, query, history, rollback, file) and how the endpoint list on the model switches individual operations on and off.

Some models exist only once per scope, for example the settings of a user. This page explains how the paths without an ID work and what happens on a second create or when the object is missing.

A general concept with several concrete types, such as “customer” with private and business customers. This page explains how the hub API forwards requests to the right subtype and when the client has to send @type.

Every response has the same envelope. This page explains what is in data and meta for a single object, a list, the history and errors.