dataobjects

DataObjects is a term used in software engineering to refer to objects whose primary purpose is to hold structured data. They encapsulate values for transport or storage and typically expose accessors rather than business logic.

DataObjects are used across layers: data access, service boundaries, and API payloads. In many languages they are implemented as simple containers such as POJOs (Plain Old Java Objects) or POCOs (Plain Old CLR Objects), commonly called data transfer objects (DTOs).

Key characteristics include a focus on data representation, potential serialization capability, and often a shallow equality model. They can be mutable or immutable depending on design; immutability improves thread safety and reliability.

Common design considerations include choosing between mutable DTOs and immutable data objects, ensuring validation at seams, versioning for schema evolution, and avoiding leakage of persistence concerns into business logic (anemic domain model).

DataObjects differ from domain entities, which carry identity and behavior, and from Value Objects, which emphasize value semantics and immutability. In practice, DataObjects may be used for mapping database rows to in-memory structures, inter-service messaging, or API responses.

Example: a simple person data object includes fields for firstName, lastName, and email. It can be serialized to JSON and mapped from a database row via an ORM.