HATEOASn

HATEOASn is not a recognized separate concept in mainstream REST literature. It is commonly considered a misspelling or informal variant of HATEOAS, which stands for Hypermedia as the Engine of Application State. In standard usage, the term refers to the architectural constraint that guides client-server interactions in RESTful systems.

HATEOAS is a design principle in which a client interacts with a network application entirely through hypermedia provided by the server. Instead of hardcoding fixed endpoints, the client discovers available actions and next steps by following hyperlinks and related controls returned in responses. This approach aims to decouple the client from server implementation details and to enable dynamic navigation as the API evolves.

In practice, responses expose hypermedia controls such as links with relational identifiers (rels) and, in some media types, embedded state or affordances. Common media formats for hypermedia include HAL, Siren, and JSON:API, each defining how links and actions are represented. The server may provide links for operations like self, next, create, update, or delete, guiding the client through valid state transitions without prior knowledge of the API’s structure.

Benefits of HATEOAS include improved evolvability, reduced need for versioning, and better runtime discoverability. Drawbacks include increased design and documentation effort, potential performance considerations, and the need for clients and servers to implement consistent hypermedia semantics.

See also HATEOAS, REST, hypermedia, HAL, Siren.