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Bytom Dapp 开发笔记(二):开发流程

比原链Bytom超级版主发布在 技术文档
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简介

这章的内容详细分析一下涉及智能合约Dapp的整个开发流程,注意是涉及只能合约,如果你只要一些基本转BTM功能没有太大意义,本内容补充一下官方提供的 比原链DAPP开发流程,详细实践过好踩到的一些坑,还有一些真正具体的技巧还有经验,个人认为非常有用,起码让开发者可以更快速地去操作。

资料说的储蓄分红合约太复杂了,简单说说逻辑,银行发了一笔股份资产,用合约锁定,用户去触发这个合约的方法,付出了钱兑换了对应份额的股份资产,当达到一定的高度,就可以通过用股份资产兑换回本金与分红(钱+利息)。 里面包含了两个合约~~

整体流程

开发流程分为,1)编写智能合约;2)发合约交易;3)测试解锁合约方法;4)基于插件钱包开发Dapp前端;5)开发后端;

流程貌似非常简单,本人在1,2,3 步浪费了很多时间。其中有些坑踩过接下来介绍一下;

1)编写智能合约,上面提供的 比原链DAPP开发流程,写得很清楚,使用的是equity非常简单,直接下载最新版 用命令 【./equity TradeOffer --instance 】 就能得到一串编译后的合约程序代码,简称智能合约程序。

E:\GoWorks\src\github.com\equity\equity>equity.exe jiedai_6.txt --instance ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff 260374 260474 260574 260674 260774 260874 260874 00141ccef16d2ac1ab22baa8acfa1633fdc32df
d55aa b1f38553d95177c53755996baf523da006da977008f069792bb6a2c3b6a253fb
======= PartLoanCollateral ======= Instantiated program:
20b1f38553d95177c53755996baf523da006da977008f069792bb6a2c3b6a253fb1600141ccef16d2ac1ab22baa8acfa1633fdc32dfd55aa030afb03030afb0303a6fa030342fa0303def903037af9030316f90320ffffffffffffffffffffffffffffffffffffffffffffffffffffffffff ffffff4d2b015b7a76529c641d010000640c0100005c7900a0695c790500f2052a01947600a0695379cd9f5579cda09a916164380000005a95639a00000054798ccd9f5679cda09a916164500000005895639a00000055798ccd9f5779cda09a916164680000005695639a00000056798ccd 9f5879cda09a916164800000005495639a00000057798ccd9f5979cda09a916164980000005295639a0000005195c3787ca169c3787c9f916164f5000000005e795479515e79c1695178c2516079c16952c3527994c251006079895f79895e79895d79895c79895b79895a79895979895879 895779895679890274787e008901c07ec1696307010000005e795479515e79c16951c3c2516079c169632b010000587acd9f6900c3c2515c7ac1632b010000755b7aaa5b7a8800c3c2515d7ac1747800c0

2)发合约交易, 先解释一下合约的逻辑,储蓄分红合约太复杂,所以我们用币币交易合约去举例子,

contract TradeOffer(assetRequested: Asset,
amountRequested: Amount,
seller: Program,
cancelKey: PublicKey) locks valueAmount of valueAsset {
clause trade() {
lock amountRequested of assetRequested with seller
unlock valueAmount of valueAsset
}
clause cancel(sellerSig: Signature) {
verify checkTxSig(cancelKey, sellerSig)
unlock valueAmount of valueAsset
}
}

看看智能合约的交易图,方便小白理解:

所以储蓄分红合约一开始肯定要锁定一部分资产,所以必须部署合约交易。那么如何触发呢?

本人通过PC钱包的接口方式去部署合约,具体很多例子可以在智能合约学习文档看到。

PC钱包方式,所有交易都必须三部,build-transaction,sign-transaction,submit-transaction,三个接口。

踩过的坑

  1. 调试智能合约很慢,要等到交易确认才能知道是否成功,而且报错不明显,不知道哪里出问题;

    解决方案:

? 本地PC钱包solonet模式调试,更改源码,快速出块 difficulty/difficulty.go

func CheckProofOfWork(hash, seed *bc.Hash, bits uint64) bool { 
    compareHash := tensority.AIHash.Hash(hash, seed)   
    return HashToBig(compareHash).Cmp(CompactToBig(bits)) <= 0
}         

? 里面那句添加 ||true 如下

return HashToBig(compareHash).Cmp(CompactToBig(bits)) <= 0 || true

一开始没想到这样做,以为很快调试好,搞了三天晚上10点才调试完。

2.智能合约对于除法的支持很不友好,尽量不要用除法,一开始写了一个很复杂的合约,不知道错误,智能逐步改代码快速调试去定位,最后发现 A/B,如果A=B没问题,否则就直接报错,问过官方没有得到合适的回答,我尝试过是存证这种问题,非常坑。

3.程序必须计算好对应结果utxo 流转action的 input、ouput ;如下

{
"base_transaction": null, "actions": [ { "output_id": "13fbd1e5df196a1488e85e3b5983e51444c49ef3695df789c9473abb636e0f5c", "arguments": [ { "type": "integer", "raw_data": { "value": 5500000000 } }, { "type": "data", "raw_data": { "value": "00141ccef16d2ac1ab22baa8acfa1633fdc32dfd55aa" } }, { "type": "integer", "raw_data": { "value": 0 } } ], "type": "spend_account_unspent_output" }, { "amount": 5500000000, "asset_id": "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", "control_program": "0014d470cdd1970**b32c52ecc9e71d795b02c79a65", "type": "control_program" }, { "amount": 5000000000, "asset_id": "80013f81a66cb99977879e31639bb4fe4b12b4c7050fe518585d3f7f159d26a9", "control_program": "00141ccef16d2ac1ab22baa8acfa1633fdc32dfd55aa", "type": "control_program" }, { "amount": 9999995000000000, "asset_id": "80013f81a66cb99977879e31639bb4fe4b12b4c7050fe518585d3f7f159d26a9", "control_program": "20b1f38553d95177c53755996baf523da006da977008f069792bb6a2c3b6a253fb160014d470cdd1970**b32c52ecc9e71d795b02c79a6503e1830403e1830403e256040322350403a21e0403e20e040307fb0320ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff4d2b015b7a76529c641d010000640c0100005c7900a0695c790500f2052a01947600a0695379cd9f5579cda09a916164380000005a95639a00000054798ccd9f5679cda09a916164500000005895639a00000055798ccd9f5779cda09a916164680000005695639a00000056798ccd9f5879cda09a916164800000005495639a00000057798ccd9f5979cda09a916164980000005295639a0000005195c3787ca169c3787c9f916164f5000000005e795479515e79c1695178c2516079c16952c3527994c251006079895f79895e79895d79895c79895b79895a79895979895879895779895679890274787e008901c07ec1696307010000005e795479515e79c16951c3c2516079c169632b010000587acd9f6900c3c2515c7ac1632b010000755b7aaa5b7a8800c3c2515d7ac1747800c0", "type": "control_program" }, { "account_id": "0U374V0300A02", "amount": 5500000000, "asset_id": "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", "type": "spend_account" }, { "account_id": "0U374V0300A02", "amount": 20000000, "asset_id": "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", "type": "spend_account" } ], "ttl": 10000 }

一个解锁合约交易要包含action类型有,

spend_account_unspent_output (合约的参数),

spend_account (输入的资产描述),

control_program或者control_address (接收者资产描述),

可以理解成质量守恒

如上面例子

spend_account_unspent_output 的action里面有个output_id =13fbd1e5df196a1488e85e3b5983e51444c49ef3695df789c9473abb636e0f5c,这个资产的小数位为8(这里没有体现),代表我要解锁这个utxo,他的值为 100000000.00000000 就是1亿。

拆分成两个action,一个 50.00000000,一个 99999950.00000000

只有btm = ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff 需要用来等手续费,所以允许不守恒,最后由旷工挖矿拿到手续费。

总结:那么程序相当于要把合约里面的逻辑整合进去,才能计算好真正的input、output~~我理解是交易确认的时候,解锁合约的程序验证现在的input、ouput是否跟合约一样。

3)测试解锁合约方法,2)里面采坑已经说清楚这个问题了,补充一下就是最好一下子不要写太复杂的合约,从简单来开发调试。一定要注意质量守恒定律,只要懂了这个原理其实非常简单。

4)基于插件钱包开发Dapp前端, 这块具体可以看插件钱包API储蓄分红合约前端源代码,里面说的非常清楚, 涉及到的接口,暂时他们API文档还没有整理出来,来自上一章说的blockcenter的接口

url地址 :testnet: ‘http://app.bycoin.io:3020/’, mainnet: ‘https://api.bycoin.im:8000/’

核心用到的接口有:

根据合约与资产ID查询UTXO接口

/api/v1/btm/q/list-utxos

参数:
{    
    "filter": {                    "script":"20b1f38553d95177c53755996baf523da006da977008f069792bb6a2c3b6a253fb160014d470cdd1970**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", 
        "asset":"80013f81a66cb99977879e31639bb4fe4b12b4c7058585d3f7f159d26a9" ,
        "unconfirmed":false
    },    
    "sort":  {
        "by":"amount", 
        "order":"desc" 
        }
}

unconfirmed ,代表是否确认的,这个对后期的并发问题非常有用,第三章我会详细说明。

结果
{
    "code": 200,
    "msg": "",
    "result": {
        "_links": {},
        "data": [
            {
                "hash": "16749b694a9f1bc6a7759cf66baefed4c864b65985e7488e8721184ecc4d6965",
                "asset": "80013f81a66cb99977879e31639bb4fe4b12b4c7058585d3f7f159d26a9",
                "amount": 3000000000
            },
            {
                "hash": "e5f75036b6f662ff705378b55dd29dc1a43acb23d701dd44a068cdab2c43ad0c",
                "asset": "80013f81a66cb99977879e31639bb4fe4b12b4c7058585d3f7f159d26a9",
                "amount": 15000000000
            }
        ],
        "limit": 10,
        "start": 0
    }
}

(自己准备参数调用一下,以上是例子而已)

查询用户地址信息与余额接口

/api/v1/btm/account/list-addresses

参数

{"guid":"b414005b-**1-4a0e-8b0f-e1cd762272f4"}

结果

{
"code": 200,
"msg": "",
"result": {
"_links": {},
"data": [{
"guid": "b414005b-**1-4a0e-8b0f-e1cd762272f4",
"address": "bm1qp4t6thlyktt6sh02scs8dqcpnk3ufk9e9pmq9s",
"label": "",
"balances": [{
"asset": "80013f81a66cb99977879e31639bb4fe4b12b4c7050fe518585d3f7f159d26a9",
"balance": "68900000000",
"total_received": "69000000000",
"total_sent": "100000000",
"decimals": 8,
"alias": "",
"in_usd": "0.00",
"in_cny": "0.00",
"in_btc": "0.000000"
}, {
"asset": "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
"balance": "1329551000",
"total_received": "53790000000",
"total_sent": "52460449000",
"decimals": 8,
"alias": "btm",
"in_usd": "1.45",
"in_cny": "10.10",
"in_btc": "0.000142"
}]
}],
"limit": 10,
"start": 0
}
}

ps:

? guid是专门插件钱包提供的,是唯一的,这个非常有用,第三章我会详细说。

查询交易信息

/api/v1/btm/account/list-transactions

参数

{"address":"bm1qp4t6thlyktt6sh02scs8dqcpnk3ufk9e9pmq9s","start":0,"limit":100}

结果

{
	"code": 200,
	"msg": "",
	"result": {
		"data": [{
			"ID": 111,
			"Hash": "471e5b267f646546be33505773186ee9d8dde2180a515df67a90d1a5f9d17bd2",
			"AssetID": "80013f81a66cb99977879e31639bb4fe4b12b4c7050fe518585d3f7f159d26a9",
			"Amount": 7000000000,
			"Address": "bm1qp4t6thlyktt6sh02scs8dqcpnk3ufk9e9pmq9s",
			"BaseID": 5,
			"Timestamp": "2019-07-08T09:23:12+08:00",
			"Height": 263728,
			"TransactionID": "471e5b267f646546be33505773186ee9d8dde2180a515df67a90d1a5f9d17bd2",
			"InputAmount": 5700000000
		}, {
			"ID": 64,
			"Hash": "e69631a8d6321d738793646399ffe022ac177a5732f562970e706ee76d49de82",
			"AssetID": "80013f81a66cb99977879e31639bb4fe4b12b4c7050fe518585d3f7f159d26a9",
			"Amount": 5000000000,
			"Address": "bm1qp4t6thlyktt6sh02scs8dqcpnk3ufk9e9pmq9s",
			"BaseID": 5,
			"Timestamp": "2019-07-05T16:37:07+08:00",
			"Height": 262170,
			"TransactionID": "e69631a8d6321d738793646399ffe022ac177a5732f562970e706ee76d49de82",
			"InputAmount": 5500000000
		}, {
			"ID": 56,
			"Hash": "cf74906808a1a6bc6a056c148510d542a10d2cbc350a4d830c670aa5ba973873",
			"AssetID": "80013f81a66cb99977879e31639bb4fe4b12b4c7050fe518585d3f7f159d26a9",
			"Amount": 39000000000,
			"Address": "bm1qp4t6thlyktt6sh02scs8dqcpnk3ufk9e9pmq9s",
			"BaseID": 5,
			"Timestamp": "2019-07-03T14:59:22+08:00",
			"Height": 261006,
			"TransactionID": "cf74906808a1a6bc6a056c148510d542a10d2cbc350a4d830c670aa5ba973873",
			"InputAmount": 8900000000
		}, {
			"ID": 54,
			"Hash": "6aedf609d47b3c06de2ce7dc9f2c99895124c80074573cd29407ac3b34ef8d40",
			"AssetID": "80013f81a66cb99977879e31639bb4fe4b12b4c7050fe518585d3f7f159d26a9",
			"Amount": 2000000000,
			"Address": "bm1qp4t6thlyktt6sh02scs8dqcpnk3ufk9e9pmq9s",
			"BaseID": 5,
			"Timestamp": "2019-07-03T12:11:12+08:00",
			"Height": 260936,
			"TransactionID": "6aedf609d47b3c06de2ce7dc9f2c99895124c80074573cd29407ac3b34ef8d40",
			"InputAmount": 5200000000
		}]
	}
}

5)开发后端,相当于bufferserver,第三章详细说明顺便我解析一下bufferserver的源码内容,还有里面踩过的坑。

总结:

这一章内容主要比较繁琐强调是调试合约方面,就是最核心的问题,这里抛出一个问题,就是UTXO问题,调试过程中非常繁琐,本来区块链不是做高并发,但是也存在并发问题,应该如何解决? 有使用过PC钱包的朋友肯定知道,里面PC钱包的UTXO,在交易过程中锁定了,没办法操作下一个,有些很多UTXO还好,如果只有一个,基本上调试跟实用都很麻烦~~~第三章我们基于原有bufferserver基础上根据官方的方案改一下,一定程度解决并发问题,大家期待一下。

参考资料:

比原链DAPP开发流程

储蓄分红合约Demo访问地址

储蓄分红合约后端bufferserver源码

储蓄分红合约前端源代码

储蓄分红合约详细说明

equity

智能合约学习文档

插件钱包API

作者:天才的饭桶

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沙发,很寂寞......
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