Semantic Web and Web 3.0 · class 11 · demo
From the chain to the graph
The registry contract of the class, running; its events turned into triples by the indexer; one SPARQL query across the chain and the domain; and a verifiable credential — signed RDF, with no chain at all. Everything below is computed live, in this process, from the class examples.
5
blocks on the in-memory chain
3
events the indexer read
21
triples · domain graph
19
triples · chain graph
In this order
1 · The contract
Log.sol, 1412 bytes, deployed at 0x8f7a45ebde…a961ea in block 8412990. 5 transactions, one refused.
2 · The indexer
3 LogCreated events, 19 triples in the chain graph — onto:OnChainRecord, onto:document, onto:block…
3 · The crossing
cross.rq over the domain graph and the chain graph. Acme Lda: anchored · Barros & Filhos, S.A.: revoked · Cerdeira Industrial: not anchored.
4 · The credential
A verifiable credential is signed RDF: 13 triples. Change one field and the signature no longer verifies.
5 · Anchor a document
Type any text: its digest, and whether the chain has it. Try registering it — on a copy that is thrown away.
An in-memory chain (the Ethereum virtual machine, @ethereumjs/evm), in this one process: no test network, no wallet, no keys, no money. Nothing a visitor does is kept.