appenduto

Appenduto is a term used in computer science to describe an append-only data ledger format and its runtime. It is designed to store records in a strictly append-only fashion, enabling efficient writes and tamper-evident reads. The data model treats each entry as an immutable event with a monotonically increasing sequence number, a timestamp, a payload, and a cryptographic hash of the previous entry to form a hash chain.

Architecture and data model: Appenduto files are organized as a sequence of blocks. Each block contains a header with version, block size, and a link to the previous block, followed by a set of records. Records are encoded with type and length fields, allowing flexible payloads. The runtime provides streaming APIs for tailing, slicing by timestamp or sequence, and checkpointing for fast recovery. Integrity is ensured by per-block checksums and an optional hash chain across blocks.

Applications and use cases: The format is intended for audit trails, immutable logs, event sourcing in microservices, and tamper-evident archival storage. It supports compression and chunked I/O and is designed to be portable across platforms. Implementations exist as reference libraries in several languages and may integrate with existing data pipelines or archival systems. Typical advantages include strong historical guarantees, deterministic replay, and straightforward verification of data lineage.

History and status: Appenduto originated in theoretical discussions of append-only storage in the mid-2020s and has since appeared in experimental projects and proposal documents. It is not part of any formal standard and is not widely deployed; its use remains niche and subject to interoperability considerations.

See also: event log, append-only file, hash chain, cryptographic integrity, log-structured storage.