Your first app ledger

Download and extract the JVM distribution, recommended for app ledgers for now. From its extracted directory:

./yano.sh start:devnet,appchain

This activates the bundled appchain profile, including orders-chain, a single-member ordered-log demo. Its deterministic key is for local testing only. It is not a multi-member security demonstration and does not turn on L1 anchoring by itself.

1. Submit an event

curl -fsS -X POST \
  http://localhost:7070/api/v1/app-chain/chains/orders-chain/messages \
  -H 'Content-Type: application/json' \
  -d '{"topic":"order-created","body":"order A-1001"}'

Save the returned messageId. The response is HTTP 202: the event has been accepted, but may not yet be finalized. See submission responses for the 400, 429, and 503 cases.

2. Read the finalized message

Replace <message-id> with the returned value. The message route returns HTTP 404 until the message is finalized, so curl -f fails until then; query again after the proposer has had time to create a block:

curl -fsS   'http://localhost:7070/api/v1/app-chain/chains/orders-chain/messages/<message-id>'
curl -fsS \
  http://localhost:7070/api/v1/app-chain/chains/orders-chain/status

3. Follow the event stream

curl -N   'http://localhost:7070/api/v1/app-chain/chains/orders-chain/stream?fromHeight=0&topic=order-created'

SSE streams finalized messages. Design consumers for reconnects and duplicate delivery using durable application checkpoints.

What the chain guarantees

ordered-log records opaque bytes in a shared finalized order. It does not enforce unique order IDs, a JSON schema, balances, or an order lifecycle. Two submissions of the same payload can produce different message IDs because their envelopes include sender sequence and expiry.

Use a custom state machine when consensus must enforce business rules. See ordered-log in depth and extension development.