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HCS‑16 API Reference

Sources

Import Paths​

import {
  HCS16Client,
  HCS16BrowserClient,
  FloraTopicType,
  FloraOperation,
  buildHcs16CreateFloraTopicTx,
  buildHcs16FloraCreatedTx,
  buildHcs16TxProposalTx,
  buildHcs16StateUpdateTx,
  buildHcs16FloraCreateRequestTx,
  buildHcs16FloraCreateAcceptedTx,
  buildHcs16FloraJoinRequestTx,
  buildHcs16FloraJoinVoteTx,
  buildHcs16FloraJoinAcceptedTx,
} from '@hashgraphonline/standards-sdk/hcs-16';

Enums​

enum FloraTopicType { COMMUNICATION=0, TRANSACTION=1, STATE=2 }
enum FloraOperation { FLORA_CREATE_REQUEST, FLORA_CREATE_ACCEPTED, FLORA_CREATED, TX_PROPOSAL, STATE_UPDATE, FLORA_JOIN_REQUEST, FLORA_JOIN_VOTE, FLORA_JOIN_ACCEPTED }

Message Schema (canonical)​

All messages share p: 'hcs-16' and an op from FloraOperation with op‑specific fields in data.

{ "p":"hcs-16", "op":"flora_created", "data": { "flora_account":"0.0.x" }, "timestamp":"…", "m":"optional" }

Node Client (HCS16Client)​

constructor(config: { network: 'mainnet'|'testnet'; operatorId: string; operatorKey: string|import('@hashgraph/sdk').PrivateKey; keyType?: 'ed25519'|'ecdsa' })

createFloraTopic(params: { floraAccountId: string; topicType: FloraTopicType; adminKey?: boolean|string|import('@hashgraph/sdk').PublicKey|import('@hashgraph/sdk').KeyList; submitKey?: boolean|string|import('@hashgraph/sdk').PublicKey|import('@hashgraph/sdk').KeyList }): Promise<{ topicId: string }>

getRecentMessages(topicId: string, options?: { limit?: number; order?: 'asc'|'desc'; opFilter?: FloraOperation|string }): Promise<Array<{ message: any; consensus_timestamp?: string; sequence_number: number }>>
getLatestMessage(topicId: string, opFilter?: FloraOperation|string): Promise<(any & { consensus_timestamp?: string; sequence_number: number }) | null>

Browser Client (HCS16BrowserClient)​

Wallet‑signed equivalents for creating topics and sending messages:

sendFloraCreated({ topicId, floraAccountId }): Promise<void>
sendTxProposal({ topicId, scheduledTxId, memo? }): Promise<void>
sendStateUpdate({ topicId, stateHash, epoch, memo? }): Promise<void>

Source

Builders (tx.ts)​

function buildHcs16CreateFloraTopicTx(params: { floraAccountId: string; topicType: FloraTopicType; adminKey?: any; submitKey?: any; operatorPublicKey?: import('@hashgraph/sdk').PublicKey }): import('@hashgraph/sdk').TopicCreateTransaction;
function buildHcs16FloraCreatedTx(params: { topicId: string; floraAccountId: string }): import('@hashgraph/sdk').TopicMessageSubmitTransaction;
function buildHcs16TxProposalTx(params: { topicId: string; scheduledTxId: string; memo?: string }): import('@hashgraph/sdk').TopicMessageSubmitTransaction;
function buildHcs16StateUpdateTx(params: { topicId: string; stateHash: string; epoch: number; memo?: string }): import('@hashgraph/sdk').TopicMessageSubmitTransaction;
function buildHcs16FloraCreateRequestTx(params: { topicId: string; members: string[]; threshold: number; seedHbar?: number }): import('@hashgraph/sdk').TopicMessageSubmitTransaction;
function buildHcs16FloraCreateAcceptedTx(params: { topicId: string; proposalSeq: number }): import('@hashgraph/sdk').TopicMessageSubmitTransaction;
function buildHcs16FloraJoinRequestTx(params: { topicId: string; candidateAccountId: string }): import('@hashgraph/sdk').TopicMessageSubmitTransaction;
function buildHcs16FloraJoinVoteTx(params: { topicId: string; candidateAccountId: string; approve: boolean }): import('@hashgraph/sdk').TopicMessageSubmitTransaction;
function buildHcs16FloraJoinAcceptedTx(params: { topicId: string; members: string[]; epoch: number }): import('@hashgraph/sdk').TopicMessageSubmitTransaction;

Validation​

  • Topic memos use numeric enum encoding: hcs-16:<floraId>:<type> or equivalent per spec section.
  • Messages validate p and op and include op‑specific data payloads.

Example​

const c = new HCS16Client({ network: 'testnet', operatorId, operatorKey });
const cTopic = await c.createFloraTopic({ floraAccountId: '0.0.600', topicType: FloraTopicType.COMMUNICATION });
await (await buildHcs16FloraCreatedTx({ topicId: cTopic.topicId, floraAccountId: '0.0.600' })).execute(c['client']);