Overview

1. Project Repository

Github Url: https://github.com/tronprotocol java-tron is the source code of the MainNet. protocol is the definition of the api and data structure. wallet-cli is the official command line wallet.

MainNet Configuration: https://github.com/tronprotocol/TronDeployment/blob/master/main_net_config.conf TestNet Configuration: https://github.com/tronprotocol/TronDeployment/blob/master/test_net_config.conf

2. SRs and Committee

2.1 How to Become a Super Representative

In TRON network, any account can apply to become a super representative candidate. Every account can vote for super representative candidates. The top 27 candidates with the most votes are the super representatives. Super representatives can produce blocks. The votes will be counted every 6 hours, so super representatives may also change every 6 hours.

To prevent vicious attack, TRON network burns 9999 TRX from the account that applies to become a super representative candidate.

2.2 Super Representatives Election

To vote, you need to have TRON Power(TP). To get TRON Power, you need to freeze TRX. Every 1 frozen TRX accounts for one TRON Power(TP). Every account in TRON network has the right to vote for a super representative candidate. After you unfreeze your frozen TRX, you will lose the responding TRON Power(TP), so your previous vote will be invalid.

Note: Only your latest vote will be counted in TRON network which means your previous vote will be over written by your latest vote.

Example (Using wallet-cli):

freezebalance 10,000,000 3 // Freeze 10 TRX to get 10 TRON Power(TP)
votewitness witness1 4 witness2 6 // Vote 4 votes for witness1, 6 votes for witness2
votewitness witness1 3 witness2 7 // Vote 3 votes for witness1, 7 votes for witness2

The final output above is: Vote 3 votes for witness1, 7 votes for witness2

2.3 Reward for Super Representatives

Votes Reward: Every 6 hours, the top 127 super representative candidates with the most votes will share a total amount of 115,200 TRX according to their votes percentage. The annual votes reward is 168,192,000 TRX in total.

Block Producing Reward: Every time after a super representative produces a block, it will be reward 32 TRX. The 27 super representatives take turns to produce blocks every 3 seconds. The annual block producing reward is 336,384,000 TRX in total.

Every time after a super representative produces a block, the 32 TRX block producing reward will be sent to it's sub-account. The sub-account is a read-only account, it allows a withdraw action from sub-account to super representative account every 24 hours.

2.4 Committee

2.4.1 What is Committee

Committee can modify the TRON network parameters, like transaction fees, block producing reward amount, etc. Committee is composed of the current 27 super representatives. Every super representative has the right to start a proposal. The proposal will be passed after it gets more than 19 approves from the super representatives and will become valid in the next maintenance period.

2.4.2 Create a Proposal

Only the account of a super representative can create a proposal. The network parameters can be modified([min,max]):

  • 0: MAINTENANCE_TIME_INTERVAL, [3 * 27* 1000, 24 * 3600 * 1000] //super representative votes count time interval, currently 6 * 3600 * 1000 ms
  • 1: ACCOUNT_UPGRADE_COST, [0, 100 000 000 000 000 000] //the fee to apply to become a super representative candidate, currently 9999_000_000 SUN
  • 2: CREATE_ACCOUNT_FEE, [0, 100 000 000 000 000 000] //the fee to create an account, currently 100_000 SUN
  • 3: TRANSACTION_FEE, [0, 100 000 000 000 000 000] //the fee for bandwidth, currently 10 SUN/byte
  • 4: ASSET_ISSUE_FEE, [0, 100 000 000 000 000 000] //the fee to issue an asset, currently 1024_000_000 SUN
  • 5: WITNESS_PAY_PER_BLOCK, [0, 100 000 000 000 000 000] //the block producing reward, currently 32_000_000 SUN
  • 6: WITNESS_STANDBY_ALLOWANCE, [0, 100 000 000 000 000 000] //the votes reward for top 127 super representative candidates, currently 115_200_000_000 SUN
  • 7: CREATE_NEW_ACCOUNT_FEE_IN_SYSTEM_CONTRACT, //the fee to create an account in system, currently 0 SUN
  • 8: CREATE_NEW_ACCOUNT_BANDWIDTH_RATE, //the consumption of bandwidth or TRX while creating an account, using together with #7
  • 9: ALLOW_CREATION_OF_CONTRACTS, //to enable the VM
  • 10: REMOVE_THE_POWER_OF_THE_GR, //to clear the votes of GR
  • 11: ENERGY_FEE, [0,100 000 000 000 000 000] //SUN
  • 12: EXCHANGE_CREATE_FEE, [0, 100 000 000 000 000 000] //SUN
  • 13: MAX_CPU_TIME_OF_ONE_TX, [0, 1000] //ms
  • 14: ALLOW_UPDATE_ACCOUNT_NAME, //to allow users to change account name and allow account duplicate name, currently 0, means false
  • 15: ALLOW_SAME_TOKEN_NAME, //to allow create a token with duplicate name, currently 1, means true
  • 16: ALLOW_DELEGATE_RESOURCE, //to enable the resource delegation
  • 17: TOTAL_ENERGY_LIMIT, //to modify the energy limit
  • 18: ALLOW_TVM_TRANSFER_TRC10, //to allow smart contract to transfer TRC-10 token, currently 0, means false

Example (Using wallet-cli):

createproposal id value
id: the serial number (0 ~ 18)
value: the parameter value

Note: In TRON network, 1 TRX = 1000_000 SUN

2.4.3 Vote for a Proposal

Proposal only support YES vote. Since the creation time of the proposal, the proposal is valid within 3 days. If the proposal does not receive enough YES votes within the period of validity, the proposal will be invalid beyond the period of validity. Yes vote can be cancelled.

Example (Using wallet-cli):

approveProposal id is_or_not_add_approval
id: proposal id
is_or_not_add_approval: YES vote or cancel YES vote

2.4.4 Cancel Proposal

Proposal creator can cancel the proposal before it is passed.

Example (Using wallet-cli):

deleteProposal id
id: proposal id

2.4.5 Query Proposal

  • Query all the proposals list (ListProposals)
  • Query all the proposals list by pagination (GetPaginatedProposalList)
  • Query a proposal by proposal id (GetProposalById)

For more api detail, please refer to Tron HTTP API

3. Account Model

3.1 Introduction

TRON uses account model. An account's identity is address, it needs private key signature to operate an account. An account has many attributes, like TRX balance, tokens balance, bandwidth, etc. TRX and tokens can be transferred from account to account and it costs bandwidth. An account can also issue a smart contract, apply to become a super representative candidate, vote, etc. All TRON's activities are based on account.

3.2 How to Create an Account

1. Use a wallet to generate the address and private key. To activate the account, you need to transfer TRX or transfer token to the new created account. generate an account

2. Use an account already existed in TRON network to create an account

3.3 Key-pair Generation Algorithm

Tron signature algorithm is ECDSA, curve used is SECP256K1. Private key is a random bumber, public key is a point in the elliptic curve. The process is: first generate a random number d to be the private key, then calculate P = d * G as the public key, G is the elliptic curve base point.

3.4 Address Format

Use the public key P as the input, by SHA3 get the result H. The length of the public key is 64 bytes, SHA3 uses Keccak256. Use the last 20 bytes of H, and add a byte of 0x41 in front of it, then the address comes out. Do basecheck to address, here is the final address. All addresses start with 'T'.

basecheck process: first do sha256 calculation to address to get h1, then do sha256 to h1 to get h2, use the first 4 bytes as check to add it to the end of the address to get address||check, do base58 encode to address||check to get the final result.

Character map: ALPHABET = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"

3.5 Signature

Signature introduction, please refer to: https://github.com/tronprotocol/Documentation/blob/fix_http/%E4%B8%AD%E6%96%87%E6%96%87%E6%A1%A3/%E4%BA%A4%E6%98%93%E7%AD%BE%E5%90%8D%E6%B5%81%E7%A8%8B.md

4. Network Node

4.1 SuperNode

4.1.1 SuperNode Introduction

Super Representative(abbr: SR) is the block producer in TRON network, there are 27 SR. They verify the transactions and write the transactions into the blocks, they take turns to produce blocks. The super Representatives' information is public to everyone in TRON network. The best way to browse is using tronscan.

4.1.2 SuperNode Deployment

SuperNode Deployment

4.1.3 Recommended Hardware Configuration

minimum requirement: CPU: 16 cores, RAM: 32G, Bandwidth: 100M, Disk: 1T Recommended requirement: CPU: > 64 cores RAM: > 64G, Bandwidth: > 500M, Disk: > 20T

4.2 FullNode

4.2.1 FullNode Introduction

FullNode has the complete block chain data, can update data in real time. It can broadcast the transactions and provide api service.

4.2.2 FullNode Deployment

please refer to TRON-Deployment

4.2.3 Recommended Hardware Configuration

Minimum requirement: CPU: 16 cores, RAM: 32G, Bandwidth: 100M, Disk: 1T Recommended requirement: CPU: > 64 cores RAM: > 64G, Bandwidth: > 500M, Disk: > 20T

4.3 SolidityNode

4.3.1 SolidityNode Introduction

SolidityNode only synchronize solidified blocks data from the fullNode it specifies, It also provie api service.

4.3.2 SolidityNode Deployment

Please refer to TRON-Deployment

4.3.3 Recommended Hardware Configuration

Minimum requirement: CPU: 16 cores, RAM: 32G, Bandwidth: 100M, Disk: 1T Recommended requirement: CPU: > 64 cores RAM: > 64G, Bandwidth: > 500M, Disk: > 20T

4.4 TRON Network Instructure

TRON network uses Peer-to-Peer(P2P) network instructure, all nodes status equal. There are three types of node: SuperNode, FullNode, SolidityNode. SuperNode produces blocks, FullNode synchronizes blocks and broadcasts transactions, SolidityNode synchronizes solidified blocks. Any device that deploy the java-tron code can join TRON network as a node. image

4.5 FullNode and SolidityNode Fast Deployment

Download fast deployment script, run the script according to different types of node. please refer to Node Fast Deployment

4.6 MainNet, TestNet, PrivateNet

MainNet, TestNet, PrivateNet all use the same code, only the node start configuration varies.

4.6.1 MainNet

MainNet configuration

4.6.2 TestNet

TestNet configuration

4.6.3 PrivateNet

4.6.3.1 Preconditions

  • at least two accounts generate an account
  • at least deploy one SuperNode to produce blocks
  • deploy serval FullNodes to synchronize blocks and broadcast transactions
  • SuperNode and FullNode comprise the private network
4.6.3.2 Deployment
4.6.3.2.1 Step 1: SuperNode Deployment

1. download private_net_config.conf

wget https://github.com/tronprotocol/tron-deployment/blob/master/private_net_config.conf
2. add your private key in localwitness 3. set genesis.block.witnesses as the private key's corresponding address 4. set p2p.version, any positive integer but 11111 5. set the first SR needSyncCheck = false, others can be set true 6. set node.discovery.enable = true 7. run the script

nohup java -Xmx6g -XX:+HeapDumpOnOutOfMemoryError -jar FullNode.jar  --witness  -c private_net_config.conf

command line parameters introduction:
--witness: start witness function, i.e.: --witness
--log-config: specify the log configuration file path, i.e.: --log-config logback.xml
-c: specify the configuration file path, i.e.: -c config.conf

The usage of the log file: You can change the level of the module to control the log output. The default level of each module is INFO, for example: only print the message with the level higher than warn: The parameters in configuration file that need to modify: localwitness: image witnesses: image version: image enable: image

4.6.3.2.2 Step 2: FullNode Deployment

1. Download private_net_config.conf

wget https://github.com/tronprotocol/tron-deployment/blob/master/private_net_config.conf
2. set seed.node ip.list with SR's ip and port 3. set p2p.version the same as SuperNode's p2p.version 4. set genesis.block the same as genesis.block 5. set needSyncCheck true 6. set node.discovery.enable true 7. run the script

 nohup java -Xmx6g -XX:+HeapDumpOnOutOfMemoryError -jar FullNode.jar  --witness  -c private_net_config.conf

 command lines parameters
 --witness: start witness function,i.e.: --witness
 --log-config: specify the log configuration file path, i.e.: --log-config logback.xml
 -c: specify the configuration file path, i.e.: -c config.conf

The usage of the log file: You can change the level of the module to control the log output. The default level of each module is INFO, for example: only print the message with the level higher than warn: The parameters in configuration file that need to modify: ip.list: image p2p.version: image genesis.block: image needSyncCheck: image node.discovery.enable: image

4.7 DB Engine

4.7.1 Rocksdb

4.7.1.1 Configuration

Use rocksdb as the data storage engine, need to set db.engine to "ROCKSDB" image Note: rocksdb only support db.version=2, do not support db.version=1

The optimization parameters rocksdb support: image

4.7.1.2 Use rocksdb's data backup function

Choose rocksdb to be the data storage engine, you can use it's data backup function while running image Note: FullNode can use data backup function. In order not to affect SuperNode's block producing performance, SuperNode does not support backup service, but SuperNode's backup service node can use this function.

4.7.1.3 Convert leveldb data to rocksdb data

The data storage structure of leveldb and rocksdb is not compatible, please make sure the node use the same type of data engine all the time. We provide data conversion script which can convert leveldb data to rocksdb data.

Usage:

 cd to the source code root directory
 ./gradlew build   #build the source code
 java -jar build/libs/DBConvert.jar  #run data conversion command
Note: If the node's data storage directory is self-defined, before run DBConvert.jar, you need to add the following parameters:

src_db_path: specify LevelDB source directory, default output-directory/database dst_db_path: specify RocksDb source directory, default output-directory-dst/database

Example, if you run the script like this:

 nohup java -jar FullNode.jar -d your_database_dir &
Then, you should run DBConvert.jar this way:
 java -jar build/libs/DBConvert.jar  your_database_dir/database  output-directory-dst/database
Note: You have to stop the running of the node, and then to run the data conversion script.

If you do not want to stop the running of the node for too long, after node is shut down, you can copy leveldb's output-directory to the new directory, and then restart the node. Run DBConvert.jar in the previous directory of the new directory, and specify the parameters: src_db_pathdst_db_path.

Example:

 cp -rf output-directory /tmp/output-directory
 cd /tmp
 java -jar DBConvert.jar output-directory/database  output-directory-dst/database
All the whole data conversion process may take 10 hours.

4.7.1.4 rocksdb vs leveldb

You can refer to: rocksdb vs leveldb ROCKSDB vs LEVELDB

5. Smart Contract

5.1 TRON Smart Contract Introduction

Smart contract is a computerized transaction protocol that automatically implements its terms. Smart contract is the same as common contract, they all define the terms and rules related to the participants. Once the contract is started, it can run in the way it is designed.

TRON smart contract support Solidity language in (Ethereum). Currently recommend Solidity language version is 0.4.24 ~ 0.4.25. Write a smart contract, then build the smart contract and deploy it to TRON network. When the smart contract is triggered, the corresponding function will be executed automatically.

5.2 TRON Smart Contract Features

TRON virtual machine is based on Ethereum solidity language, it also has TRON's own features.

5.2.1 Smart Contract

TRON VM is compatible with Ethereum's smart contract, using protobuf to define the content of the contract:

message SmartContract {
  message ABI {
    message Entry {
      enum EntryType {
        UnknownEntryType = 0;
        Constructor = 1;
        Function = 2;
        Event = 3;
        Fallback = 4;
      }
      message Param {
        bool indexed = 1;
        string name = 2;
        string type = 3;
        // SolidityType type = 3;
      }
      enum StateMutabilityType {
        UnknownMutabilityType = 0;
        Pure = 1;
        View = 2;
        Nonpayable = 3;
        Payable = 4;
      }

      bool anonymous = 1;
      bool constant = 2;
      string name = 3;
      repeated Param inputs = 4;
      repeated Param outputs = 5;
      EntryType type = 6;
      bool payable = 7;
      StateMutabilityType stateMutability = 8;
    }
    repeated Entry entrys = 1;
  }
  bytes origin_address = 1;
  bytes contract_address = 2;
  ABI abi = 3;
  bytes bytecode = 4;
  int64 call_value = 5;
  int64 consume_user_resource_percent = 6;
  string name = 7
  int64 origin_energy_limit = 8;
}

origin_address: smart contract creator address contract_address: smart contract address abi: the api information of the all the function of the smart contract bytecode: smart contract byte code call_value: TRX transferred into smart contract while call the contract consume_user_resource_percent: resource consumption percentage set by the developer name: smart contract name origin_energy_limit: energy consumption of the developer limit in one call, must greater than 0. For the old contracts, if this parameter is not set, it will be set 0, developer can use updateEnergyLimit api to update this parameter (must greater than 0)

Through other two grpc message types CreateSmartContract and TriggerSmartContract to create and use smart contracts.

5.2.2 The Usage of the Function of Smart Contract

1. constant function and inconstant function

There are two types of function according to whether any change will be made to the properties on the chain: constant function and inconstant function Constant function uses view/pure/constant to decorate, will return the result on the node it is called and not be broadcasted in the form of a transaction Inconstant function will be broadcasted in the form of a transaction while being called, the function will change the data on the chain, such as transfer, changing the value of the internal variables of contracts, etc.

Note: If you use create command inside a contract (CREATE instruction), even use view/pure/constant to decorate the dynamically created contract function, this function will still be treated as inconstant function, be dealt in the form of transaction.

2. message calls

Message calls can call the functions of other contracts, also can transfer TRX to the accounts of contract and none-contract. Like the common TRON triggercontract, Message calls have initiator, recipient, data, transfer amount, fees and return attributes. Every message call can generate a new one recursively. Contract can define the distribution of the remaining energy in the internal message call. If it comes with OutOfEnergyException in the internal message call, it will return false, but not error. In the meanwhile, only the gas sent with the internal message call will be consumed, if energy is not specified in call.value(energy), all the remaining energy will be used.

3. delegate call/call code/libary

There is a special type of message call, delegate call. The difference with common message call is the code of the target address will be run in the context of the contract that initiates the call, msg.sender and msg.value remain unchanged. This means a contract can dynamically load code from another address while running. Storage, current address and balance all point to the contract that initiates the call, only the code is get from the address being called. This gives Solidity the ability to achieve the 'lib' function: the reusable code lib can be put in the storage of a contract to implement complex data structure library.

4. CREATE command

This command will create a new contract with a new address. The only difference with Ethereum is the newly generated TRON address used the smart contract creation transaction id and the hash of nonce called combined. Different from Ethereum, the definition of nonce is the comtract sequence number of the creation of the root call. Even there are many CREATE commands calls, contract number in sequence from 1. Refer to the source code for more detail. Note: Different from creating a contract by grpc's deploycontract, contract created by CREATE command does not store contract abi.

5. built-in function and built-in function attribute (Since Odyssey-v3.1.1, TVM built-in function is not supported temporarily)

1)TVM is compatible with solidity language's transfer format, including: - accompany with constructor to call transfer - accompany with internal function to call transfer - use transfer/send/call/callcode/delegatecall to call transfer

Note: TRON's smart contract is different from TRON's system contract, if the transfer to address does not exist it can not create an account by smart contract transfer.

2)Different accounts vote for SuperNode (Since Odyssey-v3.1.1, TVM built-in function is not supported temporarily) 3)SuperNode gets all the reward (Since Odyssey-v3.1.1, TVM built-in function is not supported temporarily) 4)SuperNode approves or disapproves the proposal (Since Odyssey-v3.1.1, TVM built-in function is not supported temporarily) 5)SuperNode proposes a proposal (Since Odyssey-v3.1.1, TVM built-in function is not supported temporarily) 6)SuperNode deletes a proposal (Since Odyssey-v3.1.1, TVM built-in function is not supported temporarily) 7)TRON byte address converts to solidity address (Since Odyssey-v3.1.1, TVM built-in function is not supported temporarily) 8)TRON string address converts to solidity address (Since Odyssey-v3.1.1, TVM built-in function is not supported temporarily) 9)Send token to target address (Since Odyssey-v3.1.1, TVM built-in function is not supported temporarily) 10)Query token amount of target address (Since Odyssey-v3.1.1, TVM built-in function is not supported temporarily) 11)Compatible with all the built-in functions of Ethereum

Note: Ethereum's RIPEMD160 function is not recommended, because the return of TRON is a hash result based on TRON's sha256, not an accurate Ethereum RIPEMD160.

5.2.3 Contract Address Using in Solidity Language

Ethereum VM address is 20 bytes, but TRON's VM address is 21 bytes.

1. address conversion

Need to convert TRON's address while using in solidity (recommended):

/**
     *  @dev    convert uint256 (HexString add 0x at beginning) tron address to solidity address type
     *  @param  tronAddress uint256 tronAddress, begin with 0x, followed by HexString
     *  @return Solidity address type
*/

function convertFromTronInt(uint256 tronAddress) public view returns(address){
        return address(tronAddress);
}
This is similar with the grammar of the conversion from other types converted to address type in Ethereum.

2. address judgement

Solidity has address constant judgement, if using 21 bytes address the compiler will throw out an error, so you should use 20 bytes address, like:

function compareAddress(address tronAddress) public view returns (uint256){
        // if (tronAddress == 0x41ca35b7d915458ef540ade6068dfe2f44e8fa733c) { // compile error
        if (tronAddress == 0xca35b7d915458ef540ade6068dfe2f44e8fa733c) { // right
            return 1;
        } else {
            return 0;
        }
}
But if you are using wallet-cli, you can use 21 bytes address, like 0000000000000000000041ca35b7d915458ef540ade6068dfe2f44e8fa733c

3. variable assignment

Solidity has address constant assignment, if using 21 bytes address the compiler will throw out an error, so you should use 20 bytes address, like:

function assignAddress() public view {
        // address newAddress = 0x41ca35b7d915458ef540ade6068dfe2f44e8fa733c; // compile error
        address newAddress = 0xca35b7d915458ef540ade6068dfe2f44e8fa733c;
        // do something
}
If you want to use TRON address of string type (TLLM21wteSPs4hKjbxgmH1L6poyMjeTbHm) please refer to (2-4-7,2-4-8).

5.2.4 The Special Constants Differ from Ethereum

Currency

Like solidity supports ETH, TRON VM supports trx and sun, 1 trx = 1000000 sun, case sensitive, only support lower case. tron-studio supports trx and sun, remix does not support trx and sun. We recommend to use tron-studio instead of remix to build TRON smart contract.

Block

  • block.blockhash (uint blockNumber) returns (bytes32): specified block hash, can only apply to the latest 256 blocks and current block excluded
  • block.coinbase (address): SuperNode address that produced the current block
  • block.difficulty (uint): current block difficulty, not recommended, set 0
  • block.gaslimit (uint): current block gas limit, not supported, set 0
  • block.number (uint): current block number
  • block.timestamp (uint): current block timestamp
  • gasleft() returns (uint256): remaining gas
  • msg.data (bytes): complete call data
  • msg.gas (uint): remaining gas - since 0.4.21, not recommended, replaced by gesleft()
  • msg.sender (address): message sender (current call)
  • msg.sig (bytes4): first 4 bytes of call data (function identifier)
  • msg.value (uint): the amount of SUN send with message
  • now (uint): current block timestamp (block.timestamp)
  • tx.gasprice (uint): the gas price of transaction, not recommended, set 0
  • tx.origin (address): transaction initiator

5.3 Energy Introduction

Each command of smart contract consume system resource while running, we use 'Energy' as the unit of the consumption of the resource.

5.3.1 How to Get Energy

Freeze TRX to get energy.

Example (Using wallet-cli):

freezeBalance frozen_balance frozen_duration [ResourceCode:0 BANDWIDTH,1 ENERGY]

Freeze TRX to get energy, energy obtained = user's TRX frozen amount / total amount of frozen TRX in TRON * 50_000_000_000.

Example:

If there are only two users, A freezes 2 TRX, B freezes 2 TRX
the energy they can get is:
A: 25_000_000_000 and energy_limit is 25_000_000_000
B: 25_000_000_000 and energy_limit is 25_000_000_000

when C freezes 1 TRX:
the energy they can get is:
A: 20_000_000_000 and energy_limit is 20_000_000_000
B: 20_000_000_000 and energy_limit is 20_000_000_000
B: 10_000_000_000 and energy_limit is 10_000_000_000

Energy Recovery

The energy consumed will reduce to 0 smoothly within 24 hours.

Example:

at one moment, A has used 72_000_000 Energy
if there is no continuous consumption or TRX freeze
one hour later, the energy consumption amount will be 72_000_000 - (72_000_000 * (60*60/60*60*24)) Energy = 69_000_000 Energy
24 hours later, the energy consumption amount will be 0 Energy

5.3.2 How to Set Fee Limit (Caller Must Read)


Within the scope of this section, the smart contract developer will be called "developer", the users or other contracts which call the smart contract will be called "caller"

The amount of energy consumed while call the contract can be converted to TRX or SUN, so within the scope of this section, when refer to the consumption of the resource, there's no strict difference between Energy, TRX and SUN, unless they are used as a number unit.


Set a rational fee limit can guarantee the smart contract execution. And if the execution of the contract cost great energy, it will not consume too much energy from the caller. Before you set fee limit, you need to know several conception:

1. The legal fee limit is a integer between 0 - 10^9, unit is SUN.

2. Different smart contracts consume different amount of energy due to their complexity. The same trigger in the same contract almost consumes the same amount fo energy[1]. When the contract is triggered, the commands will be executed one by one and consume energy. If it reaches the fee limit, commands will fail to be executed, and energy is not refundable.

3. Currently fee limit only refers to the energy converted to SUN that will be consumed from the caller[2]. The energy consumed by triggering contract also includes developer's share.

4. For a vicious contract, if it encounters execution timeout or bug crash, all it's energy will be consumed.

5. Developer may undertake a proportion of energy consumption(like 90%). But if the developer's energy is not enough for consumption, the rest of the energy consumption will be undertaken by caller completely. Within the fee limit range, if the caller does not have enough energy, then it will burn equivalent amount of TRX [2].

To encourage caller to trigger the contract, usually developer has enough energy.

Example

How to estimate the fee limit:

Assume contract C's last execution consumes 18000 Energy, so estimate the energy consumption limit to be 20000 Energy[3]

According to the frozen TRX amount and energy conversion, assume 1 TRX = 400 energy.

When to burn TRX, 1 TRX = 10000 energy[4]

Assume developer undertake 90% energy consumption, and developer has enough energy.

Then the way to estimate the fee limit is:

1). A = 20000 energy * (1 TRX / 400 energy) = 50 TRX = 50_000_000 SUN, 2). B = 20000 energy * (1 TRX / 10000 energy) = 2 TRX = 2_000_000 SUN, 3). Take the greater number of A and B, which is 50_000_000 SUN, 4). Developer undertakes 90% energy consumption, caller undertakes 10% energy consumption,

So, the caller is suggested to set fee limit to 50_000_000 SUN * 10% = 5_000_000 SUN

Note:

[1] The energy consumption of each execution may fluctuate slightly due to the situation of all the nodes. [2] TRON may change this policy. [3] The estimated energy consumption limit for the next execution should be greater than the last one. [4] 1 TRX = 10^4 energy is a fixed number for burning TRX to get energy, TRON may change it in future.

5.3.3 Energy Calculation (Developer Must Read)

1. In order to punish the vicious developer, for the abnormal contract, if the execution times out (more than 50ms) or quits due to bug (revert not included), the maximum available energy will be deducted. If the contract runs normally or revert, only the energy needed for the execution of the commands will be deducted.

2. Developer can set the proportion of the energy consumption it undertakes during the execution, this proportion cna be changed later. If the developer's energy is not enough, it will consume the caller's energy.

3. Currently, the total energy available when trigger a contract is composed of caller fee limit and developer's share

Note: - If the developer is not sure about whether the contract is normal, do not set caller's energy consumption proportion to 0%, in case all developer's energy will be deducted due to vicious execution[1]. - We recommend to set caller's energy consumption proportion to 10% ~ 100%[2].

Example 1

A has an account with a balance of 90 TRX(90000000 SUN) and 10 TRX frozen for 100000 energy.

Smart contract C set the caller energy consumption proportion to 100% which means the caller will pay for the energy consumption completely.

A triggers C, the fee limit set is 30000000 (unit SUN, 30 TRX)

So during this trigger the energy A can use is from two parts: - A's energy by freezing TRX; - The energy converted from the amount of TRX burning according to a fixed rate;

If fee limit is greater than the energy obtained from freezing TRX, then it will burn TRX to get energy. The fixed rate is: 1 Energy = 100 SUN, fee limit still has (30 - 10) TRX = 20 TRX available, so the energy it can keep consuming is 20 TRX / 100 SUN = 200000 energy.

Finally, in this call, the energy A can use is (100000 + 200000) = 300000 energy.

If contract executes successfully without any exception, the energy needed for the execution will be deducted. Generally, it is far more less than the amount of energy this trigger can use.

If Assert-style error come out, it will consume the whole number of energy set for fee limit.

Assert-style error introduction, refer to https://github.com/tronprotocol/Documentation/blob/master/%E4%B8%AD%E6%96%87%E6%96%87%E6%A1%A3/%E8%99%9A%E6%8B%9F%E6%9C%BA/%E5%BC%82%E5%B8%B8%E5%A4%84%E7%90%86.md

Example 2

A has an account with a balance of 90 TRX(90000000 SUN) and 10 TRX frozen for 100000 energy.

Smart contract C set the caller energy consumption proportion to 40% which means the developer will pay for the rest 60% energy consumption.

Developer D freezes 50 TRX to get 500000 energy.

A triggers C, the fee limit set is 200000000 (unit SUN, 200 TRX).

So during this trigger the energy A can use is from three parts: - A's energy by freezing TRX -- X; - The energy converted from the amount of TRX bruning according to a fixed rate -- Y; If fee limit is greater than the energy obtained from freezing TRX, then it will burn TRX to get energy. The fixed rate is: 1 Energy = 100 SUN, fee limit still has (200 - 10) TRX = 190 TRX available, but A only has 90 TRX left, so the energy it can keep consuming is 90 TRX / 100 SUN = 900000 energy; - D's energy by freezing TRX -- Z;

There are two situation: if (X + Y) / 40% >= Z / 60%, the energy A can use is X + Y + Z if (X + Y) / 40% < Z / 60%, the energy A can use is (X + Y) / 40%

If contract executes successfully without any exception, the energy needed for the execution will be deducted. Generally, it is far more less than the amount of energy this trigger can use.

If Assert-style error comes out, it will consume the whole number of energy set for fee limit. Assert-style error introduction, refer to (https://github.com/tronprotocol/Documentation/blob/master/%E4%B8%AD%E6%96%87%E6%96%87%E6%A1%A3/%E8%99%9A%E6%8B%9F%E6%9C%BA/%E5%BC%82%E5%B8%B8%E5%A4%84%E7%90%86.md)

Note: when developer create a contract, do not set consume_user_resource_percent to 0, which means developer will undertake all the energy consumption. If Assert-style error comes out, it will consume all energy from the developer itsef.

Assert-style error introduction, refer to https://github.com/tronprotocol/Documentation/blob/master/%E4%B8%AD%E6%96%87%E6%96%87%E6%A1%A3/%E8%99%9A%E6%8B%9F%E6%9C%BA/%E5%BC%82%E5%B8%B8%E5%A4%84%E7%90%86.md

To avoid unnecessary lost, 10 - 100 is recommended for consume_user_resource_percent.

5.4 Smart Contract Development Tool

5.4.1 TronStudio

Support the build, debug, run, etc. for solidity language written smart contract. https://developers.tron.network/docs/tron-studio-intro

5.4.2 TronBox

Support the build, deploy, transplant, etc. for solidity language written smart contract. https://developers.tron.network/docs/tron-box-user-guide

5.4.3 TronWeb

Provide http api service for the usage of smart contract. https://developers.tron.network/docs/tron-web-intro

5.4.4 TronGrid

Provide smart contract event query service. https://developers.tron.network/docs/tron-grid-intro

5.5 Using Command Lines Tool to Develop Smart Contract

First you can use TronStudio to write, build and debug the smart contract. After you finish the development of the contract, you can copy it to SimpleWebCompiler to compile to get ABI and ByteCode. We provide a simple data read/write smart contract code example to demonstrate:

pragma solidity ^0.4.0;
contract DataStore {

    mapping(uint256 => uint256) data;

    function set(uint256 key, uint256 value) public {
        data[key] = value;
    }

    function get(uint256 key) view public returns (uint256 value) {
        value = data[key];
    }
}

Start a Private Net

Make sure the fullnode code has been deployed locally, you can check if 'Produce block successfully' log appears in FullNode/logs/tron.log

Develop a Smart Contract

Copy the code example above to remix to debug.

Compile in SimpleWebCompiler for ABI and ByteCode

Copy the code example above to SimpleWebCompiler to get ABI and ByteCode. Because TRON's compiler is a little different from Ethereum, so you can not get ABI and ByteCode by using Remix. But it will soon be supported.

Using Wallet-cli to Deploy

Download Wallet-Cli and build

shell
# download cource code
git clone https://github.com/tronprotocol/wallet-cli
cd  wallet-cli
# build
./gradlew build
cd  build/libs

Note: You need to change the node ip and port in config.conf

start wallet-cli

java -jar wallet-cli.jar

after started, you can use command lines to operate:

importwallet
<input your password twice for your account>
<input your private key>
login
<input your password you set>
getbalance

deploy contract

Shell
# contract deployment command
DeployContract contractName ABI byteCode constructor params isHex fee_limit consume_user_resource_percent <value> <library:address,library:address,...>

# parameters
contract_name: Contract name
ABI: ABI from SimpleWebCompiler
bytecode: ByteCode from SimpleWebCompiler
constructor: When deploy contract, this will be called. If is needed, write as constructor(uint256,string). If not, just write #
params: The parameters of the constructor, use ',' to split, like  1, "test", if no constructor, just write #
fee_limit: The TRX consumption limit for the deployment, unit is SUN(1 SUN = 10^-6 TRX)
consume_user_resource_percent: Consume user's resource percentage. It should be an integer between [0, 100]. if 0, means it does not consume user's resource until the developer's resource has been used up
value: The amount of TRX transfer to the contract when deploy
library: If the contract contains library, you need to specify the library address

# example
deploycontract DataStore [{"constant":false,"inputs":[{"name":"key","type":"uint256"},{"name":"value","type":"uint256"}],"name":"set","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"key","type":"uint256"}],"name":"get","outputs":[{"name":"value","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"}] 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 # # false 1000000 30 0
If it is deployed successfully, it will return 'Deploy the contract successfully'

get the contract address

Your smart contract address will be: <contract address>

# in this example
Your smart contract address will be: TTWq4vMEYB2yibAbPV7gQ4mrqTyX92fha6

call the contract to store data, query data

Shell
# call contract command
triggercontract <contract_address> <method> <args> <is_hex> <fee_limit> <value>

# parameters
contract_address: Contract address, like TTWq4vMEYB2yibAbPV7gQ4mrqTyX92fha6
method: The method called, like set(uint256,uint256) or fool(), use ',' to split the parameters. Do not leave space between parameters
args: The parameters passed to the method called, use ',' to split the parameters. Do not leave space between parameters
is_hex: whether the input parameters is Hex, false or true
fee_limit: The TRX consumption limit for the trigger, unit is SUN(1 SUN = 10^-6 TRX)
value: The amount of TRX transfer to the contract when trigger

# trigger example
## set mapping 1->1
triggercontract TTWq4vMEYB2yibAbPV7gQ4mrqTyX92fha6 set(uint256,uint256) 1,1 false 1000000  0000000000000000000000000000000000000000000000000000000000000000

## get mapping key = 1
triggercontract TTWq4vMEYB2yibAbPV7gQ4mrqTyX92fha6 get(uint256) 1 false 1000000  0000000000000000000000000000000000000000000000000000000000000000

If the function called is constant or view, wallet-cli will return the result directly. If it contains library, before deploy the contract you need to deploy the library first. After you deploy library, you can get the library address, then fill the address in library:address,library:address,...

# for instance, using remix to get the bytecode of the contract, like:
608060405234801561001057600080fd5b5061013f806100206000396000f300608060405260043610610041576000357c0100000000000000000000000000000000000000000000000000000000900463ffffffff168063f75dac5a14610046575b600080fd5b34801561005257600080fd5b5061005b610071565b6040518082815260200191505060405180910390f35b600073<b>__browser/oneLibrary.sol.Math3__________<\b>634f2be91f6040518163ffffffff167c010000000000000000000000000000000000000000000000000000000002815260040160206040518083038186803b1580156100d357600080fd5b505af41580156100e7573d6000803e3d6000fd5b505050506040513d60208110156100fd57600080fd5b81019080805190602001909291905050509050905600a165627a7a7230582052333e136f236d95e9d0b59c4490a39e25dd3a3dcdc16285820ee0a7508eb8690029

The address of the library deployed before is: TSEJ29gnBkxQZR3oDdLdeQtQQykpVLSk54 When you deploy, you need to use browser/oneLibrary.sol.Math3:TSEJ29gnBkxQZR3oDdLdeQtQQykpVLSk54 as the parameter of deploycontract.

6. Built-in Contracts and API

6.1 Built-in Contracts

Please refer to: https://github.com/tronprotocol/Documentation/blob/master/%E4%B8%AD%E6%96%87%E6%96%87%E6%A1%A3/%E6%B3%A2%E5%9C%BA%E5%8D%8F%E8%AE%AE/%E4%BA%A4%E6%98%93%E6%93%8D%E4%BD%9C%E7%B1%BB%E5%9E%8B%E8%AF%B4%E6%98%8E.md

6.2 GRPC API Introduction

Please refer to: https://github.com/tronprotocol/Documentation/blob/master/%E4%B8%AD%E6%96%87%E6%96%87%E6%A1%A3/%E6%B3%A2%E5%9C%BA%E5%8D%8F%E8%AE%AE/%E6%B3%A2%E5%9C%BA%E9%92%B1%E5%8C%85RPC-API.md

6.3 Http API Introduction

Please refer to: https://github.com/tronprotocol/Documentation/blob/master/TRX_CN/Tron-http.md

7. TRC-10 Token Introduction

TRON network support two types of token, one is TRC-20 token issued by smart contract, the other one is TRC-10 token issued by system contract.

7.1 How to Issue a TRC-10 Token

HTTP API:

wallet/createassetissue
Description: Issue a token
demo: curl -X POST  http://127.0.0.1:8090/wallet/createassetissue -d '{
"owner_address":"41e552f6487585c2b58bc2c9bb4492bc1f17132cd0",
"name":"0x6173736574497373756531353330383934333132313538",
"abbr": "0x6162627231353330383934333132313538",
"total_supply" :4321,
"trx_num":1,
"num":1,
"start_time" : 1530894315158,
"end_time":1533894312158,
"description":"007570646174654e616d6531353330363038383733343633",
"url":"007570646174654e616d6531353330363038383733343633",
"free_asset_net_limit":10000,
"public_free_asset_net_limit":10000,
"frozen_supply":{"frozen_amount":1, "frozen_days":2}
}'
Parameter owner_address: Owner address, default hexString
Parameter name: Token name, default hexString
Parameter abbr: Token name abbreviation, default hexString
Parameter total_supply: Token total supply
Parameter trx_num: Define the price by the ratio of trx_num/num,
Parameter num: Define the price by the ratio of trx_num/num
Parameter start_time: ICO start time
Parameter end_time: ICO end time
Parameter description: Token description, default hexString
Parameter url: Token official website url, default hexString
Parameter free_asset_net_limit: Token free asset net limit
Parameter public_free_asset_net_limit: Token public free asset net limit
Parameter frozen_supply: Token frozen supply
Parameter permission_id: Optional, for multi-signature use
Return: Transaction object
Note: The unit of 'trx_num' is SUN

7.2 Participate TRC-10 Token

HTTP API:

wallet/participateassetissue
Description: Participate a token
demo: curl -X POST http://127.0.0.1:8090/wallet/participateassetissue -d '{
"to_address": "41e552f6487585c2b58bc2c9bb4492bc1f17132cd0",
"owner_address":"41e472f387585c2b58bc2c9bb4492bc1f17342cd1",
"amount":100,
"asset_name":"3230313271756265696a696e67"
}'
Parameter to_address: The issuer address of the token, default hexString
Parameter owner_address: The participant address, default hexString
Parameter amount: Participate token amount
Parameter asset_name: Token id, default hexString
Parameter permission_id: Optional, for multi-signature use
Return: Transaction object
Note: The unit of 'amount' is the smallest unit of the token

7.3 TRC-10 Token Transfer

HTTP API:

wallet/transferasset
Description: Transfer token
demo: curl -X POST  http://127.0.0.1:8090/wallet/transferasset -d '{"owner_address":"41d1e7a6bc354106cb410e65ff8b181c600ff14292", "to_address": "41e552f6487585c2b58bc2c9bb4492bc1f17132cd0", "asset_name": "31303030303031", "amount": 100}'
Parameter owner_address: Owner address, default hexString
Parameter to_address: To address, default hexString
Parameter asset_name: Token id, default hexString
Parameter amount: Token transfer amount
Parameter permission_id: Optional, for multi-signature use
Return: Transaction object
Note: The unit of 'amount' is the smallest unit of the token

8. Resource Model

8.1 Resource Model Introduction

TRON network has 4 types of resources: Bandwidth, CPU, Storage and RAM. Benefit by TRON's exclusive RAM model, TRON's RAM resource is almost infinite.

TRON network imports two resource conceptions: Bandwidth points and Energy. Bandwidth Point represents Bandwidth, Energy represents CPU and Storage.

Note: - Ordinary transaction only consumes Bandwidth points - Smart contract related transaction not only consumes Bandwidth points, but also Energy

8.2 Bandwidth Points

The transaction information is stored and transmitted in the form of byte array, Bandwidth Points consumed = the number of bytes of the transaction * Bandwidth Points rate. Currently Bandwidth Points rate = 1

Such as if the number of bytes of a transaction is 200, so this transaction consumes 200 Bandwidth Points.

Note: Due to the change of the total amount of the frozen TRX in the network and the self-frozen TRX amount, the Bandwidth Points an account possesses is not fixed.

8.2.1 How to Get Bandwidth Points

1. By Freezing TRX to get Bandwidth Points, Bandwidth Points = the amount of TRX self-frozen / the total amount of TRX frozen for Bandwidth Points in the network * 43_200_000_000

2. Every account has a fixed amount of free Bandwidth Points(5000) every day

8.2.2 Bandwidth Points Consumption

Except for query operation, any transaction consumes Bandwidth points.

There's another situation: When you transfer(TRX or token) to an account that does not exist in the network, this operation will first create that account in the network and then do the transfer. It only consumes Bandwidth points for account creation, no extra Bandwidth points consumption for transfer.

Create a new account transaction, Bandwidth points consumption sequence:

1. Bandwidth points from freezing TRX. If transaction initiator does not have enough Bandwidth Points of this type, it will go to step 2; 2. Burn 0.1 TRX;

Token transfer transaction, Bandwidth points consumption sequence:

1. 依次验证 发行Token资产总的免费Bandwidth Points是否足够消耗,转账发起者的Token剩余免费Bandwidth Points是否足够消耗, Token发行者冻结TRX获取Bandwidth Points剩余量是否足够消耗。如果满足则扣除Token发行者的Bandwidth Points,任意一个不满足则进入下一步。 2. Bandwidth points from freezing TRX. If transaction initiator does not have enough Bandwidth Points of this type, it will go to step 3; 3. Free Bandwidth points. If transaction initiator does not have enough Bandwidth Points of this type, it will go to step 4; 4. Bandwidth points from burning TRX, the rate = the number of bytes of the transaction * 10 SUN;

Ordinary transaction, Bandwidth points consumption sequence:

1. Bandwidth points from freezing TRX. If transaction initiator does not have enough Bandwidth Points of this type, it will go to step 2; 2. Free Bandwidth points. If transaction initiator does not have enough Bandwidth Points of this type, it will go to step 3; 3. Bandwidth points from burning TRX, the rate = the number of bytes of the transaction * 10 SUN;

8.2.3 Bandwidth Points Recovery

Every 24 hours, the amount of the usage of Bandwidth points of an account will be reset to 0. For the specific formula: image

Every 24 hours, the amount of the usage of Bandwidth points of an account will be reset to 0.

8.3 Energy

5.3 Energy Introduction

8.4 Resource Delegation

In TRON network, an account can freeze TRX for Bandwidth or Energy for other accounts. The primary account owns the frozen TRX and TRON power, the recipient account owns the Bandwidth or Energy. Like ordinary freezing, resource delegation freezing is also at least 3 days.

  • Example(Using wallet-cli)
    freezeBalance frozen_balance frozen_duration [ResourceCode:0 BANDWIDTH,1 ENERGY] [receiverAddress]
    
    frozen_balance: the amount of TRX to freeze (unit SUN)
    frozen_duration: the freezing period (currently a fixed 3 days)
    ResourceCode: 0 for Bandwidth, 1 for Energy
    receiverAddress: recipient account address
    

8.5 Other Fees

Type Fee
Create a witness 9999 TRX
Issue a token 1024 TRX
Create an account 0.1 TRX
Create an exchange 1024 TRX

9. DEX Introduction

TRON network supports decentralized exchange(DEX) using Bancor protocol. DEX is composed of many exchange pairs.

9.1 What is an Exchange Pair

The term of 'Exchange Pair' describes a trade between one token with another, like A/B, A/TRX.

9.2 Exchange Pair Creation

Any account can create an exchange pair, it burns 1024 TRX.

Please refer to 'wallet/exchangecreate': https://github.com/tronprotocol/documentation/blob/master/TRX/Tron-http.md

9.3 Exchange Pair Transaction

Any account can trade in the DEX. The trade follows Bancor protocol.

Please refer to 'wallet/exchangetransaction': https://github.com/tronprotocol/documentation/blob/master/TRX/Tron-http.md

9.4 Exchange Pair Injection

The exchange pair creator can inject more tokens into the exchange pair. Injection can decrease the range of ratio fluctuation. If one token is injected, the other one will be injected automatically to keep the current ratio of the two tokens unchanged.

Please refer to 'wallet/exchangeinject': https://github.com/tronprotocol/documentation/blob/master/TRX/Tron-http.md

9.5 Exchange Pair Withdrawal

The exchange pair creator can withdraw tokens from the exchange pair. Withdrawal can increase the range of ratio fluctuation. If one token is withdrawn, the other one will be withdrawn automatically to keep the current ratio of the two tokens unchanged.

Please refer to 'wallet/exchangewithdraw': https://github.com/tronprotocol/documentation/blob/master/TRX/Tron-http.md)

9.6 Query

9.6.1 Transaction Query

ListExchanges: Query the list of all the exchange pairs GetPaginatedExchangeList: Query the list of all the exchange pairs by pagination GetExchangeById: Query an exchange pair by exchange pair id

Please refer to: https://github.com/tronprotocol/documentation/blob/master/TRX/Tron-http.md

9.6.2 Price Calculation

The token price is determined by the ratio of the balance of the two tokens.

9.6.3 Calculate the Amount of Token You Can Get

sellTokenQuant is the amount of the first_token you want to sell; buyTokenQuant is the amount of second_token you can get; supply = 1_000_000_000_000_000_000L; supplyQuant = -supply * (1.0 - Math.pow(1.0 + (double) sellTokenQuant/(firstTokenBalance + sellTokenQuant, 0.0005)); buyTokenQuant = (long)balance * (Math.pow(1.0 + (double) supplyQuant / supply, 2000.0) - 1.0);

10. Multi-Signatures

Please refer to: Multi-signatures

11. Shielded Transaction

Please refer to: Shielded Transaction

12. Wallet Introduction

12.1 wallet-cli Introduction

Please refer to: https://github.com/tronprotocol/wallet-cli/blob/master/README.md

12.2 Get Transaction ID

Hash.sha256(transaction.getRawData().toByteArray())

12.3 Get Block ID

private byte[] generateBlockId(long blockNum, byte[] blockHash) {
  byte[] numBytes = Longs.toByteArray(blockNum);
  byte[] hash = blockHash;
  System.arraycopy(numBytes, 0, hash, 0, 8);
  return hash;
 }

12.4 How to Build a Transaction Locally

According to the defination of the transaction, you need to fill up all the fields of the transaction.

You need to set reference block and expiration time information, so you need to connect to the Mainnet. We recommend to use the latest block on fullnode as the value of reference block, use the latest block time plus N minutes as the value of expiration time.

The network judgment condition is if (expiration > latest block time and expiration < latest block time + 24 hours) means the transaction is in period of validity. Otherwise, it will be an overdue transaction, will not be accepted by the Mainnet.

Way to set reference block: set RefBlockHash the bytes from the 8 to 16(not included) of the hash of the latest block, set BlockBytes the bytes from 6 to 8(not included) of the height of the latest block.

public static Transaction setReference(Transaction transaction, Block newestBlock) {
     long blockHeight = newestBlock.getBlockHeader().getRawData().getNumber();
     byte[] blockHash = getBlockHash(newestBlock).getBytes();
     byte[] refBlockNum = ByteArray.fromLong(blockHeight);
     Transaction.raw rawData = transaction.getRawData().toBuilder()
         .setRefBlockHash(ByteString.copyFrom(ByteArray.subArray(blockHash, 8, 16)))
         .setRefBlockBytes(ByteString.copyFrom(ByteArray.subArray(refBlockNum, 6, 8)))
         .build();
     return transaction.toBuilder().setRawData(rawData).build();
   }
Way to set expiration time and transaction timestamp:
public static Transaction createTransaction(byte[] from, byte[] to, long amount) {
     Transaction.Builder transactionBuilder = Transaction.newBuilder();
     Block newestBlock = WalletClient.getBlock(-1);

     Transaction.Contract.Builder contractBuilder = Transaction.Contract.newBuilder();
     Contract.TransferContract.Builder transferContractBuilder = Contract.TransferContract
         .newBuilder();
     transferContractBuilder.setAmount(amount);
     ByteString bsTo = ByteString.copyFrom(to);
     ByteString bsOwner = ByteString.copyFrom(from);
     transferContractBuilder.setToAddress(bsTo);
     transferContractBuilder.setOwnerAddress(bsOwner);
     try {
       Any any = Any.pack(transferContractBuilder.build());
       contractBuilder.setParameter(any);
     } catch (Exception e) {
       return null;
     }
     contractBuilder.setType(Transaction.Contract.ContractType.TransferContract);
     transactionBuilder.getRawDataBuilder().addContract(contractBuilder)
         .setTimestamp(System.currentTimeMillis()) //in the form of millisecond
         .setExpiration(newestBlock.getBlockHeader().getRawData().getTimestamp() + 10 * 60 * 60 * 1000);
     Transaction transaction = transactionBuilder.build();
     Transaction refTransaction = setReference(transaction, newestBlock);
     return refTransaction;
   }

12.5 Related Demo

Build transaction locally, signature demo, please refer to: https://github.com/tronprotocol/wallet-cli/blob/master/src/main/java/org/tron/demo/TransactionSignDemo.java nodejs demo, please refer to: https://github.com/tronprotocol/tron-demo/tree/master/demo/nodejs