Dagelement

Dagelement is a primitive unit used in directed acyclic graph (DAG) based dataflow and reactive programming to represent a single data value as it traverses a computation. It is designed to carry not only the value itself but also essential metadata that supports traceability and reproducibility of processing.

A dagelement typically includes an identifier, the stored value, data type or schema information, a timestamp, and provenance data describing its origin and the operation that produced it. It may also contain references to predecessor dagelements, forming a lightweight dependency graph that helps reconstruct the computation that led to the current element.

Key properties of a dagelement include immutability after creation, ease of serialization for storage or transmission, and often a compact, memory-efficient representation. In many implementations dagelements are hashable and versioned, enabling reliable deduplication and historical replay of data pipelines.

In practice, dagelements serve as the fundamental payloads that flow through DAG nodes. Each node consumes one or more dagelements, performs a transformation, and emits new dagelements to downstream nodes. This design supports data lineage, incremental computation, and fault tolerance, since the history of each data item is captured in its metadata.

Implementation notes are architecture dependent; dagelements may be stored in memory for fast processing or serialized to on-disk formats for persistence. They are commonly found in data processing frameworks, stream processors, and reactive systems that require deterministic, traceable pipelines.

See also: directed acyclic graph, data lineage, provenance, data element, data pipeline.