Build your client to interact with any of the Hedera network nodes. Mainnet, testnet, and previewnet are the three Hedera networks you can submit transactions and queries to.
For a predefined network (preview, testnet, and mainnet), the mirror node client is configured to the corresponding network mirror node. The default mainnet mirror node connection is to the whitelisted mirror node.
To access the public mainnet mirror node, use setMirrorNetwork() and enter mainnet-public.mirrornode.hedera.com:433 for the endpoint. The gRPC API requires TLS. The following SDK versions are compatible with TLS:
Java: v2.3.0+
JavaScript: v2.4.0+
Go: v2.4.0+
// From a pre-configured networkClient client =Client.forTestnet();//For a specified networkMap<String,AccountId> nodes =newHashMap<>();nodes.put("34.94.106.61:50211",AccountId.fromString("0.0.10"));Client.forNetwork(nodes);//v2.0.0
// From a pre-configured networkconstclient=Client.forTestnet();//For a specified networkconstnodes= {"34.94.106.61:50211":newAccountId(10)}constclient=Client.forNetwork(nodes);//v2.0.7
// From a pre-configured networkclient := hedera.ClientForTestnet()//For a specified networknode :=map[string]AccountID{"34.94.106.61:50211": {Account: 10}}client := Client.forNetwork(nodes)//v2.0.0
2. Define the operator account ID and private key
The operator is the account that will, by default, pay the transaction fee for transactions and queries built with this client. The operator account ID is used to generate the default transaction ID for all transactions executed with this client. The operator private key is used to sign all transactions executed by this client.
From an account ID and private key
// Operator account ID and private key from string valueAccountId MY_ACCOUNT_ID =AccountId.fromString("0.0.96928");Ed25519PrivateKey MY_PRIVATE_KEY = PrivateKey.fromString("302e020100300506032b657004220420b9c3ebac81a72aafa5490cc78111643d016d311e60869436fbb91c7330796928");
// Pre-configured client for test network (testnet)Client client =Client.forTestnet()//Set the operator with the account ID and private keyclient.setOperator(MY_ACCOUNT_ID, MY_PRIVATE_KEY);
// Your account ID and private key from string valueconstMY_ACCOUNT_ID=AccountId.fromString("0.0.96928");const MY_PRIVATE_KEY = PrivateKey.fromString("302e020100300506032b657004220420b9c3ebac81a72aafa5490cc78111643d016d311e60869436fbb91c7330796928");
// Pre-configured client for test network (testnet)constclient=Client.forTestnet()//Set the operator with the account ID and private keyclient.setOperator(MY_ACCOUNT_ID,MY_PRIVATE_KEY);
// Operator account ID and private key from string valueoperatorAccountID, err := hedera.AccountIDFromString("0.0.96928")if err !=nil {panic(err)}operatorKey, err := hedera.PrivateKeyFromString("302e020100300506032b65700422042012a4a4add3d885bd61d7ce5cff88c5ef2d510651add00a7f64cb90de33596928")
if err !=nil {panic(err)}// Pre-configured client for test network (testnet)client := hedera.ClientForTestnet()//Set the operator with the operator ID and operator keyclient.SetOperator(operatorAccountID, operatorKey)
From a .env file
The .env file is created in the root directory of the SDK. The .env file stores account ID and the associated private key information to reference throughout your code. You will need to import the relevant dotenv module to your project files. The sample .env file may look something like this:
//Grab the account ID and private key of the operator account from the .env fileAccountId MY_ACCOUNT_ID =AccountId.fromString(Objects.requireNonNull(Dotenv.load().get("OPERATOR_ID")));Ed25519PrivateKey MY_PRIVATE_KEY = Ed25519PrivateKey.fromString(Objects.requireNonNull(Dotenv.load().get("OPERATOR_KEY")));
// Pre-configured client for test network (testnet)Client client =Client.forTestnet()//Set the operator with the account ID and private keyclient.setOperator(MY_ACCOUNT_ID, MY_PRIVATE_KEY);
//Grab the account ID and private key of the operator account from the .env fileconstmyAccountId=process.env.MY_ACCOUNT_ID;constmyPrivateKey=process.env.MY_PRIVATE_KEY;// Pre-configured client for test network (testnet)constclient=Client.forTestnet()//Set the operator with the account ID and private keyclient.setOperator(myAccountId, myPrivateKey);
err := godotenv.Load(".env")if err !=nil {panic(fmt.Errorf("Unable to load environment variables from demo.env file. Error:\n%v\n", err)) }//Get the operator account ID and private key MY_ACCOUNT_ID := os.Getenv("MY_ACCOUNT_ID") MY_PRIVATE_KEY := os.Getenv("MY_PRIVATE_KEY") myAccountID, err := hedera.AccountIDFromString(MY_ACCOUNT_ID)if err !=nil {panic(err) } myPrivateKey, err := hedera.PrivateKeyFromString(MY_PRIVATE_KEY)if err !=nil {panic(err) }
3. Additional client modifications
The max transaction fee and max query payment are both set to 100_000_000 tinybar (1 HBAR). This amount can be modified by using setDefaultMaxTransactionFee()and setDefaultMaxQueryPayment().
// For test network (testnet)Client client =Client.forTestnet()//Set your account as the client's operatorclient.setOperator(myAccountId, myPrivateKey);//Set the default maximum transaction fee (in Hbar)client.setDefaultMaxTransactionFee(newHbar(10));//Set the maximum payment for queries (in Hbar)client.setDefaultMaxQueryPayment(newHbar(5));//v2.0.0
JavaScript
// For test network (testnet)const client =Client.forTestnet()//Set your account as the client's operatorclient.setOperator(myAccountId, myPrivateKey);//Set the default maximum transaction fee (in Hbar)client.setDefaultMaxTransactionFee(newHbar(10));//Set the maximum payment for queries (in Hbar)client.setDefaultMaxQueryPayment(newHbar(5));//v2.0.0
// For test network (testnet)client := hedera.ClientForTestnet()//Set your account as the client's operatorclient.SetOperator(myAccountId, myPrivateKey)// Set default max transaction feeclient.SetDefaultMaxTransactionFee(hedera.HbarFrom(10, hedera.HbarUnits.Hbar))// Set max query paymentclient.setDefaultMaxQueryPayment(hedera.HbarFrom(5, hedera.HbarUnits.Hbar))//v2.0.0
Constructs a Hedera client pre-configured for Previewnet access
Client.forTestnet()
Constructs a Hedera client pre-configured for Testnet access
Client.forMainnet()
Constructs a Hedera client pre-configured for Mainnet access
Client.forNetwork(<network>)
Map<String, AccountId>
Construct a client given a set of nodes. It is the responsibility of the caller to ensure that all nodes in the map are part of the same Hedera network. Failure to do so will result in undefined behavior.
Configure a client based on a JSON file at the given path.
Client.forName(<name>)
String
Provide the name of the network.
mainnettestnetpreviewnet
Client.<network>.setMirrorNetwork(<network>)
List<String>
Define a specific mirror network node(s) ip:port in string format
Client.<network>.getMirrorNetwork()
List<String>
Return the mirror network node(s) ip:port in string format
Client.setTransportSecurity()
boolean
Set if transport security should be used. If transport security is enabled all connections to nodes will use TLS, and the server's certificate hash will be compared to the hash stored in the node address book for the given network.
Client.setNetworkUpdatePeriod()
Duration
Client automatically updates the network via a mirror node query at regular intervals. You can set the interval at which the address book is updated.
Client.setNetworkFromAddressBook(<addressBook>)
AddressBook
Client can be set from a NodeAddressBook.
Client.setLedgerId(<ledgerId>)
LedgerId
The ID of the network.
LedgerId.MAINNETLedgerId.TESTNETLedgerId.PREVIEWNET
Client.getLedgerId()
LedgerId
Get the ledger ID
Client.setVerifyCertificates()
boolean
Set if server certificates should be verified against an existing address book.
The period of time a transaction or query request will retry from a "busy" network response
Client.<network>.getRequestTimeout()
Duration
Get the period of time a transaction or query request will retry from a "busy" network response
Client.<network>.setMinBackoff(<minBackoff>)
Duration
The minimum amount of time to wait between retries. When retrying, the delay will start at this time and increase exponentially until it reaches the maxBackoff
Client.<network>.getMinBackoff()
Duration
Get the minimum amount of time to wait between retries
Client.<network>.setMaxBackoff(<maxBackoff>)
Duration
The maximum amount of time to wait between retries. Every retry attempt will increase the wait time exponentially until it reaches this time.
Client.<network>.getMaxBackoff()
Duration
Get the maximum amount of time to wait between retries