Node SDK (HCS17Client)

The SDK publishes and verifies HCS‑17 state hashes using an operator account. It centralizes topic creation and message submission while delegating all transaction construction to tx.ts / tx.go.

Setup

TypeScript

import { HCS17Client } from '@hashgraphonline/standards-sdk';

const client = new HCS17Client({
  network: 'testnet',
  operatorId: process.env.ACCOUNT_ID!,
  operatorKey: process.env.PRIVATE_KEY!, // string or PrivateKey
  keyType: 'ed25519', // or 'ecdsa' if needed
  logLevel: 'info',
});

Go

import (
	"os"

	"github.com/hashgraph-online/standards-sdk-go/pkg/hcs17"
)

client, err := hcs17.NewClient(hcs17.ClientConfig{
	Network:            "testnet",
	OperatorAccountID:  os.Getenv("HEDERA_ACCOUNT_ID"),
	OperatorPrivateKey: os.Getenv("HEDERA_PRIVATE_KEY"),
})

Create a State Topic

Topics for HCS‑17 messages must use the numeric memo format hcs-17:<type>:<ttl>.

TypeScript

const topicId = await client.createStateTopic({
  ttl: 86400,
  // adminKey/submitKey can be boolean | string | PublicKey | KeyList
});

Go

topicID, err := client.CreateStateTopic(ctx, hcs17.CreateTopicOptions{
	TTLSeconds: 86400,
	// AdminKey / SubmitKey can be configured here
})

The client validates memo structure via parseHCS17Memo and exposes validateHCS17Topic(topicId) if you need to verify existing topics.

Submit a Message

If you already have a computed state hash and topic list, build a valid payload and submit:

TypeScript

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

const message: StateHashMessage = client.createStateHashMessage(
  'abc123…',              // stateHash
  '0.0.1234',             // accountId
  ['0.0.2001','0.0.2002'],// topics
  'optional memo',        // m
);

await client.submitMessage(topicId, message);

Go

message := client.CreateStateHashMessage(
	"abc123…",               // stateHash
	"0.0.1234",              // accountId
	[]string{"0.0.2001", "0.0.2002"}, // topics
	"optional memo",         // m
	nil,                     // epoch
)

receipt, err := client.SubmitMessage(ctx, topicID, message, "transaction memo")

Compute and Publish

The high‑level helper fetches latest running hashes from Mirror Node, computes the HCS‑17 account state hash, and publishes it to a target topic.

TypeScript

const { stateHash, receipt } = await client.computeAndPublish({
  accountId: '0.0.1234',
  accountPublicKey: '302a30…', // or PublicKey
  topics: ['0.0.2001', '0.0.2002'],
  publishTopicId: topicId,
  memo: 'app context',
});

console.log('Published state hash:', stateHash);

Go

result, err := client.ComputeAndPublish(ctx, hcs17.ComputeAndPublishOptions{
	AccountID:        "0.0.1234",
	AccountPublicKey: "302a30…",
	Topics:           []string{"0.0.2001", "0.0.2002"},
	PublishTopicID:   topicID,
	Memo:             "app context",
})

fmt.Println("Published state hash:", result.StateHash)

Read Latest Messages

Mirror‑node helpers return parsed, schema‑validated HCS‑17 envelopes:

TypeScript

const recent = await client.getRecentMessages(topicId, { limit: 25, order: 'desc' });
const latest = await client.getLatestMessage(topicId);

Go

recent, err := client.GetRecentMessages(ctx, topicID, 25, "desc")
latest, err := client.GetLatestMessage(ctx, topicID)

Notes

• No dynamic imports are used; signing occurs with the configured operator.
• All transaction JSON is constructed in tx.ts builders (buildHcs17CreateTopicTx, buildHcs17MessageTx).
• Memos use numeric enums (HCS17TopicType.STATE = 0).