microchain-client

Client-side tooling for committing rows from an on-premises SQL database into a remote SkipLedger microchain hosted by a microchain-webservices instance.

How it works

A microchain records the tamper-evident history of a SQL table (or view). Rather than sending raw data to the server, the client computes a SHA-256 hash of each row locally and submits only those hashes. The server appends them to a SkipLedger, a hash-pointer data structure that lets any third party verify the chain's integrity with a logarithmic-sized proof.

The commit workflow:

1. Fetch chain metadata from the server (/info, /salts, /sql-config).
2. Open a local SqlLedger with the returned JDBC queries and salt config.
3. Query /state to find the current committed row count.
4. Hash the next batch of rows locally via SqlLedger.
5. POST the hashes to /commit; receive the updated row count.

Modules

Module	Artifact	Purpose
microchain-api	io.crums:microchain-api	REST contract — DTOs and JSON parsers shared with the server
microchain-http	io.crums:microchain-http	java.net.http client implementing SkipLedger over the REST API
microchain-cli	io.crums:microchain-cli	picocli command-line tool that drives the commit workflow

REST API surface

All endpoints are namespaced under /{user}/{chain}/:

Verb	Path	Description
GET	/info	Chain metadata: ledger type, title, salt scheme
GET	/salts	Salt seeds (secret, requires access token)
GET	/sql-config	JDBC queries and optional connection URL
GET	/state	Current skip-ledger state (PathPack JSON) — public
POST	/commit	Append row hashes — requires Bearer access token

Dependencies

• skipledger-base (io.crums.sldg.base) — SkipLedger, PathPack, SaltScheme, TableSalt
• sql-ledger (io.crums.sldg.src.sql) — SqlLedger (local row hashing over JDBC)
• jsonimple (io.crums.jsonimple) — lightweight JSON library used for all parsing (except in the Quarkus server)
• picocli 4.7.5 — CLI framework (cli module only)

Build

mvn package

Java 22+, Maven 3.9+.