For example: To get the signature from the APP, the current thinking is that the front-end signs through Dapp, and after signing the signature, it is processed through the back-end chainService service.

APP interface copywriting:

get_signedTx：

js：

{

	"timestamp":"" //string
	
	"method": "get_signedTx"//string
	
	"data":{
	
		"from":""//string
		
		"message":""//string
		
		"tx":{
		
			"to":""//string
			
			"value":""//string
			
			"data":""//string
			
			"nonce":""//string
			
			"gas":""//string
			
			"gasPrice":""//string
			
			"chainId":""//string
			
			"coin":""//string can be ""
			
			"chainType":""//string "0","1".....
			
			"contract":""//string "true"/"eth"
			
			"contractAddress":""//string is not ""
		
		}
		
	}

}

app：

{

	"timestamp":"" //string
	
	"method": "get_signedTx"//string
	
	"data":{
	
		"ok":true/false//bool
		
		"rawTx":""//string
		
	}

}

In addition, there are several points to note for the use of dapp:

1. First call the TPxxx interface of the chainService service version XX to obtain the chain data, and obtain the corresponding nonce, gasLimit, and gasPrice; call method AG:

Parameters:
{
 address: "Wallet Address",
 chain: "Node chain mark 0: Initial chain 1: Initial chain testnet 2: Ethereum 3: Ethereum testnet 4: Bitcoin",
 ethFunction: {
  inputParameters: [{
   type: "address",
   value: "Coin address"
  }, {
   type: "uint256",
   value: "Receive coins Gwei, example 1000000000000000000"
  }],
  name: "Call ABIname, example transfer",
  outputParameters: [{
   "type": "bool"
  }]
 }
}
 Description:
 The inputParameters and outputParameters depend on the configuration writing method corresponding to ABIname. 

2. JS assembly example:

let gasPrice = new Decimal(divnew Decimal1000000000000000000toFixed// gasLimit is the upper limit of gas available in a transaction, gas is the paid miner fee, gasPrice is how much Gwei is willing to pay for 1 unit of gas and ether
let txParams = to: "Coin address",
value: "0",
data: "The function that returns the result in the first step",
nonce: "The first step returns the nonce of the result",
gas: "The first step returns the limitToken of the result",
gasPrice: gasPricetoString,
chainId: ,
coin:"",
chainType: "Chain node tag", 
contract: "Coin Contract Chain Type", 
contractAddress: