9. What is missing to do it for real
The demo shows the mechanism. Using it for real with a company needs choices that no contract can make on its own.
Who checks that the actors are who they say
In the demo each actor is a fictional user with a wallet held by the backend ("simple custody"). In the real world you need verified identities of companies and people (for example through a business register or a certification body), and a safe way to grant and remove roles.
The first link
The chain guarantees data does not change after being written, not that it was true when written. That is why physical checks and inspections are needed: an accredited laboratory, seals, spot checks.
Consortia and standards
A register is truly useful if the whole supply chain uses the same one. Protection consortia and associations can define the data format and who may write.
European rules
Regulation (EU) 2024/1781 on ecodesign (ESPR) introduces the digital product passport: product data available through a code. Food and feed, however, are among the products excluded from the scope of the ESPR (Article 1; the official text is on EUR-Lex), so olive oil is not covered by this passport. It will apply to the product groups the Commission selects in later acts: the 2025-2030 working plan lists, for example, textiles among the priorities, and for batteries the passport comes from Regulation (EU) 2023/1542, due by 18 February 2027. For olive oil the food rules remain (traceability, lot, label). The passport is useful here only as an example of direction, not as an obligation.
Costs
Every write on the chain has a cost. Recording one document fingerprint per lot, not per bottle, keeps the bill low. On the test network coins are worthless; on a real network they must be budgeted.
Privacy
Whatever is written on the chain can be read forever. So only data that may be public goes there: no names of individuals, no personal data, and documents stay outside with only their fingerprint.
What we built
PietreDiVita.solon Polygon Amoy (Chain ID 80002):0x158a5026eD83888a443f2bA921Faf07C2D04bE0E
The backend keeps the documents and computes the hashes (chapter 7); the public page is the one in chapter 8. These are test-network contracts: tokens and coins have no value.
Source code. The full source code is available on request.
Try it yourself
Pick a product you know (wine, honey, cheese) and write three questions a system like this cannot solve on its own, like those in the paragraphs above.
What you learned
- Verified identities and physical checks are needed, not just technology.
- The chain makes data immutable, not true.
- Costs and privacy are handled by writing little: fingerprints, not documents.