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Transactions (tx.ts)

Note

  • These builders are for direct transaction construction (e.g., with the Standards Agent Kit or custom pipelines).
  • For most applications, prefer the higher‑level sdk.ts (Node) or browser.ts (wallet) clients.

All HCS‑18 transactions and payloads are constructed via builders in tx.ts. Clients do not hand‑assemble JSON.

Sources

Topic Memo​

import { buildHcs18DiscoveryMemo } from '@hashgraphonline/standards-sdk';

buildHcs18DiscoveryMemo();          // 'hcs-18:0'
buildHcs18DiscoveryMemo(300);       // 'hcs-18:0:300'
buildHcs18DiscoveryMemo(undefined, 'custom'); // 'custom'

Parameters

  • ttlSeconds? number: Optional freshness hint encoded in the topic memo.
  • memoOverride? string: Use a custom memo string (bypasses the standard memo format). Prefer for legacy topics or migrations.

Create Discovery Topic​

import { buildHcs18CreateDiscoveryTopicTx } from '@hashgraphonline/standards-sdk';

const tx = buildHcs18CreateDiscoveryTopicTx({
  ttlSeconds: 300,
  adminKey,         // optional, boolean | Key
  submitKey,        // optional, boolean | Key
  operatorPublicKey // optional, used for defaults
});

Parameters

  • ttlSeconds? number: Encoded into the memo as hcs-18:0:<ttl>.
  • adminKey? MaybeKey: Allows setting topic admin; if true, uses operator key; or pass a specific key.
  • submitKey? MaybeKey: Restricts submissions; if true, uses operator key; or pass a specific key.
  • operatorPublicKey? PublicKey: Helpful for defaulting admin/submit when passing boolean flags.
  • memoOverride? string: Full memo override.

Returns

  • TopicCreateTransaction ready to sign and execute.

Usage

  • Node: await tx.execute(client).then(r => r.getReceipt(client))
  • Browser: await (await tx.freezeWithSigner(signer)).executeWithSigner(signer) then getReceiptWithSigner (advanced).

Submit Message​

import { buildHcs18SubmitDiscoveryMessageTx } from '@hashgraphonline/standards-sdk';

const tx = buildHcs18SubmitDiscoveryMessageTx({
  topicId: '0.0.x',
  message: { p: 'hcs-18', op: 'announce', data: { account: '0.0.123', petal: { name: 'A', priority: 700 }, capabilities: { protocols: ['hcs-16','hcs-18'] } } },
  transactionMemo: 'optional',
});

Parameters

  • topicId string: Discovery topic ID.
  • message DiscoveryMessage: One of the typed HCS‑18 envelopes (see below).
  • transactionMemo? string: Optional Hedera transaction memo.

Returns

  • TopicMessageSubmitTransaction ready to sign and execute.

Announce — buildHcs18AnnounceMessage​

Signature

buildHcs18AnnounceMessage(data: AnnounceData): DiscoveryMessage

Example

import { buildHcs18AnnounceMessage } from '@hashgraphonline/standards-sdk';

const msg = buildHcs18AnnounceMessage({
  account: '0.0.123',
  petal: { name: 'A', priority: 700 },
  capabilities: { protocols: ['hcs-16','hcs-18'] },
  valid_for: 300,
});

AnnounceData​

type AnnounceData = {
  account: string; // Hedera account ID of the Petal
  petal: { name: string; priority: number };
  capabilities: {
    protocols: string[];
    resources?: { compute?: 'high'|'medium'|'low'; storage?: 'high'|'medium'|'low'; bandwidth?: 'high'|'medium'|'low' };
    group_preferences?: { sizes?: number[]; threshold_ratios?: number[] };
  };
  valid_for?: number; // Optional time window hint for availability
};

Propose — buildHcs18ProposeMessage​

Signature

buildHcs18ProposeMessage(data: ProposeData): DiscoveryMessage

Example

import { buildHcs18ProposeMessage } from '@hashgraphonline/standards-sdk';

const msg = buildHcs18ProposeMessage({
  proposer: '0.0.1',
  members: [{ account: '0.0.2', priority: 500 }],
  config: { name: 'Demo Flora', threshold: 2 },
});

ProposeData​

type ProposeData = {
  proposer: string; // Hedera account of proposer
  members: Array<{ account: string; announce_seq?: number; priority: number }>;
  config: { name: string; threshold: number; purpose?: string; reason?: string };
  existing_flora?: string; // For replacement flows
};

Respond — buildHcs18RespondMessage​

Signature

buildHcs18RespondMessage(data: RespondData): DiscoveryMessage

Example

import { buildHcs18RespondMessage } from '@hashgraphonline/standards-sdk';

const msg = buildHcs18RespondMessage({
  responder: '0.0.2',
  proposal_seq: 10,
  decision: 'accept',
});

RespondData​

type RespondData = {
  responder: string; // Hedera account of the responding Petal
  proposal_seq: number; // Sequence number of the proposal message
  decision: 'accept' | 'reject';
  reason?: string;
  accepted_seq?: number;
};

Complete — buildHcs18CompleteMessage​

Signature

buildHcs18CompleteMessage(data: CompleteData): DiscoveryMessage

Example

import { buildHcs18CompleteMessage } from '@hashgraphonline/standards-sdk';

const msg = buildHcs18CompleteMessage({
  proposer: '0.0.1',
  proposal_seq: 10,
  flora_account: '0.0.500',
  topics: { communication: '0.0.600', transaction: '0.0.601', state: '0.0.602' },
});

CompleteData​

type CompleteData = {
  proposer: string;
  proposal_seq: number;
  flora_account: string;
  topics: { communication: string; transaction: string; state: string };
};

Withdraw — buildHcs18WithdrawMessage​

Signature

buildHcs18WithdrawMessage(data: WithdrawData): DiscoveryMessage

Example

import { buildHcs18WithdrawMessage } from '@hashgraphonline/standards-sdk';

const msg = buildHcs18WithdrawMessage({
  account: '0.0.2',
  announce_seq: 42,
  reason: 'going offline',
});

WithdrawData​

type WithdrawData = {
  account: string;
  announce_seq: number;
  reason?: string;
};

Notes

  • Use the builders to ensure the p: 'hcs-18' and op fields are correct.
  • Builders return plain JSON; pair with buildHcs18SubmitDiscoveryMessageTx to create a signed transaction.