How to Use ChemIDplus for Tezos Library

Introduction

ChemIDplus offers a fast, REST‑based lookup of chemical identifiers that you can embed directly into a Tezos smart‑contract library. By fetching a chemical’s CID (Compound ID) and converting it to a Michelson‑compatible type, developers can reference real‑world chemical data on‑chain. This guide shows you how to query the service, map the response to Tezos data structures, and deploy a working example. Follow the steps to integrate accurate chemical data without leaving the Tezos ecosystem.

Key Takeaways

• ChemIDplus REST API returns JSON containing the CID, synonyms, and properties for any chemical.
• Convert the JSON CID to a Tezos string or bytes type for on‑chain storage.
• Use the Tezos SDK (e.g., Taquito) to call a contract entrypoint that accepts the mapped identifier.
• Ensure API rate limits and data freshness are handled in the off‑chain service layer.
• Compare ChemIDplus with PubChem and ChemSpider to pick the right source for your library.

What is ChemIDplus?

ChemIDplus is a free, NIH‑maintained database that aggregates chemical identity information, including IUPAC names, CAS registry numbers, and the unique CID used by PubChem. The service exposes a lightweight HTTP endpoint that accepts a search term and returns a JSON payload with the matching record. You can explore the API documentation on the PubChem site.

Why ChemIDplus Matters for a Tezos Library

Smart contracts often need reference data that cannot be stored efficiently on‑chain. By using ChemIDplus, a Tezos library can retrieve authoritative chemical identifiers on demand, reducing storage costs and keeping the contract logic clean. The CID serves as a compact, stable key that downstream services can dereference to obtain full property sets when needed. This approach aligns with the finance‑editor mindset: deliver reliable, up‑to‑date information without bloating the ledger.

How ChemIDplus Works

The workflow follows a simple request‑response model:

1. Request: GET https://chem.senescence.nl/chemidplus/<search_term> (or the official NIH endpoint) with optional parameters for output format.
2. Response: JSON containing fields such as id, name, cid, synonyms.
3. Mapping: Extract the cid value and convert it to a Tezos string (or bytes for compact storage).
4. On‑chain call: Submit the mapped value to a contract entrypoint that expects a chemical identifier.

Mathematically, the conversion can be expressed as:

tezos_cid = to_string(chemidplus_response.cid)  // string
tezos_bytes = pack(tezos_cid)                     // bytes

The pack operation ensures the identifier fits the Michelson type required by the contract.

Used in Practice

Below is a minimal implementation using JavaScript and the Taquito library:

const axios = require('axios');
const { TezosToolkit } = require('@taquito/taquito');

async function fetchChemId(searchTerm) {
  const url = `https://pubchem.ncbi.nlm.nih.gov/rest/pug/compound/name/${encodeURIComponent(searchTerm)}/property/IUPACName,Title/JSON`;
  const { data } = await axios.get(url);
  return data.PropertyTable.Properties[0];
}

async function pushToTezos(tezos, contractAddress, cidString) {
  const contract = await tezos.contract.at(contractAddress);
  const op = await contract.methodsObject.update_chemical(cidString).send();
  await op.confirmation();
  console.log('Transaction confirmed:', op.hash);
}

(async () => {
  const tezos = new TezosToolkit('https://mainnet.tezos.org');
  const chemical = await fetchChemId('aspirin');
  const cidString = String(chemical.CID);
  await pushToTezos(tezos, 'KT1...', cidString);
})();

This script fetches the CID for aspirin, converts it to a string, and pushes it to a contract named update_chemical. Adjust the entrypoint and contract address to match your library design.

Risks / Limitations

1. API Rate Limits: NIH endpoints cap requests per second; implement caching or batch requests to avoid 429 errors.

2. Data Freshness: Chemical records change; off‑chain services must refresh identifiers periodically.

3. On‑chain Size: Storing large strings inflates gas costs; prefer bytes or a hash of the CID when possible.

4. Legal Compliance: Some jurisdictions restrict on‑chain references to hazardous chemicals; verify compliance before deployment.

ChemIDplus vs. PubChem vs. ChemSpider

ChemIDplus aggregates data from multiple sources, offering a quick CID lookup without the full property set. PubChem provides richer data (3‑D structures, bioactivity) but requires more API calls. ChemSpider emphasizes cheminformatics features and offers a different schema. For a Tezos library that needs a lightweight identifier, ChemIDplus strikes the best balance between speed and reliability.

What to Watch

Monitor the NIH’s API versioning announcements; breaking changes could affect your query parameters. Keep an eye on Tezos protocol upgrades that may introduce new data types or lower gas costs for bytes handling. Additionally, watch for community‑driven caching layers that could improve response times and reduce external dependencies.

FAQ

Can I use ChemIDplus without an API key?

Yes, the NIH provides free, unauthenticated access to basic endpoints, though rate limits apply.

How do I handle missing CID results?

Return a default placeholder (e.g., “UNKNOWN”) and log the failure for manual review.

What Tezos SDK works best for this integration?

Taquito is the most widely used JavaScript SDK, but you can also use the Python or Rust SDKs if you prefer other ecosystems.

Is it safe to store chemical identifiers on‑chain?

Storing the CID itself is safe; the on‑chain value is just a reference. Always verify off‑chain data before using it in contract logic.

How do I convert a CID to bytes in Michelson?

Use the built‑in PACK instruction to serialize the string representation of the CID into bytes before storage.

Can I query multiple chemicals in a single request?

Yes, ChemIDplus supports batch queries via the property parameter and can return results for up to 100 compounds per call.

What happens if the NIH API changes its response schema?

Maintain a thin adapter layer that extracts only the fields you need; update the adapter when the schema changes to keep the contract logic untouched.

Do I need to pay for gas when reading data from ChemIDplus?

No, gas costs apply only when you write to the Tezos blockchain; fetching data from ChemIDplus is an off‑chain operation.