deltav1

Deltav1 is a delta encoding format and patch protocol used to represent incremental changes to binary data and text files. A deltav1 patch encodes the difference between a source version and a target version as a compact sequence of operations, enabling patch application without transmitting entire files. It is designed for efficiency in networks and storage, facilitating faster synchronization and reduced bandwidth compared to sending full copies.

Origin and scope: The name deltav1 is used by multiple projects to denote the first formal version of their delta encoding scheme. There is no single universal specification; implementations vary in header layout, command encoding, and compression strategy. Common goals include deterministic patch application, streaming support, and optional integrity checks.

Format basics: A deltav1 patch starts with a small header including a version field, lengths of source and target data, and a patch checksum. The patch body comprises a sequence of commands, typically including add commands that insert new bytes and copy commands that copy data from the source or from previously emitted patch data. Patches may be combined with compression, such as zlib or LZ4, to further reduce size.

Applications and usage: Deltav1 is used in file synchronization, software update delivery, database replication, and content delivery networks where small changes need to be propagated efficiently. It supports streaming application, where patches are consumed as they arrive, enabling near real-time updates.

Security and integrity: Patch validity is critical; patches should be authenticated and validated before application to prevent tampering or corruption. Recommended practices include cryptographic signatures, integrity hashes, and strict version checks during patch application.