储蓄分红DAPP
储蓄分红合约简介
储蓄分红合约指的是项目方发起了一个锁仓计划（即储蓄合约和取现合约），用户可以在准备期自由选择锁仓金额参与该计划，等到锁仓到期之后还可以自动获取锁仓的利润。用户可以在准备期内（dueBlockHeight）参与储蓄，按照合约规定可以 1：1 获取同等数量的储蓄票据资产，同时用户锁仓的资产（deposit）将放到取现合约中，并且项目方是无法动用的，等到锁仓期限（expireBlockHeight）一到，用户便可以调用取现合约将自己储蓄的资产连本待息一同取出来。其示意图如下:
从上图中可以看出，项目方发布了一个利润为20%的锁仓项目，其中储蓄合约FixedLimitCollect锁定了1000个票据资产（bill），同时项目方将200个储蓄资产（deposit）锁定到利息合约中。待项目方发布完合约之后，所有用户便可以参与了。例如上图中user1调用合约储蓄了500，这500个储蓄资产将被锁定在取现合约FixedLimitProfit中，同时user1获得了500个票据资产，剩余找零的资产将继续锁定在储蓄合约FixedLimitCollect中，以此类推，user2和user3也是相同的流程，直到储蓄合约没有资产为止。取现合约FixedLimitProfit跟储蓄合约的模型大致相同，只是取现合约是由多个UTXO组成的，用户在取现的时候可以并行操作。但是如果合约中的面值不能支持用户一次性取现的话，需要分多次提取。例如user1拥有500个票据资产，而可以获得的本息总额为600，但是取现的UTXO面值为500,那么user1一次最多只能取500,剩下的100需要再构造一笔交易来提现。
合约源代码
// 储蓄合约
import "./FixedLimitProfit"
contract FixedLimitCollect(assetDeposited: Asset,
totalAmountBill: Amount,
totalAmountCapital: Amount,
dueBlockHeight: Integer,
expireBlockHeight: Integer,
additionalBlockHeight: Integer,
banker: Program,
bankerKey: PublicKey) locks billAmount of billAsset {
clause collect(amountDeposited: Amount, saver: Program) {
verify below(dueBlockHeight)
verify amountDeposited <= billAmount && totalAmountBill <= totalAmountCapital
define sAmountDeposited: Integer = amountDeposited/100000000
define sTotalAmountBill: Integer = totalAmountBill/100000000
verify sAmountDeposited > 0 && sTotalAmountBill > 0
if amountDeposited < billAmount {
lock amountDeposited of assetDeposited with FixedLimitProfit(billAsset, totalAmountBill, totalAmountCapital, expireBlockHeight, additionalBlockHeight, banker, bankerKey)
lock amountDeposited of billAsset with saver
lock billAmount-amountDeposited of billAsset with FixedLimitCollect(assetDeposited, totalAmountBill, totalAmountCapital, dueBlockHeight, expireBlockHeight, additionalBlockHeight, banker, bankerKey)
} else {
lock amountDeposited of assetDeposited with FixedLimitProfit(billAsset, totalAmountBill, totalAmountCapital, expireBlockHeight, additionalBlockHeight, banker, bankerKey)
lock billAmount of billAsset with saver
}
}
clause cancel(bankerSig: Signature) {
verify above(dueBlockHeight)
verify checkTxSig(bankerKey, bankerSig)
unlock billAmount of billAsset
}
}
// 取现合约(本金加利息)
contract FixedLimitProfit(assetBill: Asset,
totalAmountBill: Amount,
totalAmountCapital: Amount,
expireBlockHeight: Integer,
additionalBlockHeight: Integer,
banker: Program,
bankerKey: PublicKey) locks capitalAmount of capitalAsset {
clause profit(amountBill: Amount, saver: Program) {
verify above(expireBlockHeight)
define sAmountBill: Integer = amountBill/100000000
define sTotalAmountBill: Integer = totalAmountBill/100000000
verify sAmountBill > 0 && sTotalAmountBill > 0 && amountBill < totalAmountBill
define gain: Integer = totalAmountCapital*sAmountBill/sTotalAmountBill
verify gain > 0 && gain <= capitalAmount
if gain < capitalAmount {
lock amountBill of assetBill with banker
lock gain of capitalAsset with saver
lock capitalAmount - gain of capitalAsset with FixedLimitProfit(assetBill, totalAmountBill, totalAmountCapital, expireBlockHeight, additionalBlockHeight, banker, bankerKey)
} else {
lock amountBill of assetBill with banker
lock capitalAmount of capitalAsset with saver
}
}
clause cancel(bankerSig: Signature) {
verify above(additionalBlockHeight)
verify checkTxSig(bankerKey, bankerSig)
unlock capitalAmount of capitalAsset
}
}
合约的源代码说明可以具体参考Equity合约介绍.
注意事项：
- 时间期限不是具体的时间，而是通过区块高度来大概估算的（平均区块时间间隔大概为
2.5分钟） - 比原的精度是
8, 即1BTM = 100000000 neu，正常情况下参与计算都是以neu为单位的，然而虚拟机的int64类型的最大值是9223372036854775807，为了避免数值太大导致计算溢出，所以对计算的金额提出了金额限制（即amountBill/100000000） - 另外
clause cancel是项目方的管理方法，如果储蓄或者取现没有满额，项目方也可以回收剩余的资产
编译并实例化合约
编译Equity合约可以参考一下Equity编译器的介绍说明。假如储蓄合约FixedLimitCollect的参数如下：
assetDeposited :c6b12af8326df37b8d77c77bfa2547e083cbacde15cc48da56d4aa4e4235a3ee
totalAmountBill :10000000000
totalAmountCapital :20000000000
dueBlockHeight :1070
expireBlockHeight :1090
additionalBlockHeight :1100
banker :0014dedfd406c591aa221a047a260107f877da92fec5
bankerKey :055539eb36abcaaf127c63ae20e3d049cd28d0f1fe569df84da3aedb018ca1bf
其中bankerKey是管理员的publicKey，可以通过比原链的接口list-pubkeys来获取，注意管理员需要保存一下对应的rootXpub和Path，否则无法正确调用clause cancel。
实例化合约命令如下：
// 储蓄合约
./equity FixedLimitCollect --instance c6b12af8326df37b8d77c77bfa2547e083cbacde15cc48da56d4aa4e4235a3ee 10000000000 20000000000 1070 1090 1100 0014dedfd406c591aa221a047a260107f877da92fec5 055539eb36abcaaf127c63ae20e3d049cd28d0f1fe569df84da3aedb018ca1bf
// 取现合约
./equity FixedLimitProfit --instance c6b12af8326df37b8d77c77bfa2547e083cbacde15cc48da56d4aa4e4235a3ee 10000000000 20000000000 1090 1100 0014dedfd406c591aa221a047a260107f877da92fec5 055539eb36abcaaf127c63ae20e3d049cd28d0f1fe569df84da3aedb018ca1bf
发布合约交易
发布合约交易即将资产锁定到合约中。由于目前无法在比原的dashboard上构造合约交易，所以需要借助外部工具来发送合约交易，比如postman。按照上述示意图所示，项目方需要发布1000个储蓄资产的储蓄合约和200个利息资产取现合约。假设项目方需要发布1000个储蓄资产（假如精度为8,那么1000个在比原链中表示为100000000000）的锁仓合约，那么他需要将对应数量的票据锁定在储蓄合约中，其交易模板如下：
{
"base_transaction": null,
"actions": [
{
"account_id": "0ILGLSTC00A02",
"amount": 20000000,
"asset_id": "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
"type": "spend_account"
},
{
"account_id": "0ILGLSTC00A02",
"amount": 100000000000,
"asset_id": "13016eff73ffb7539a69e122f80f5c1cc94446773ac3f64dec290429f87e73b3",
"type": "spend_account"
},
{
"amount": 100000000000,
"asset_id": "13016eff73ffb7539a69e122f80f5c1cc94446773ac3f64dec290429f87e73b3",
"control_program": "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",
"type": "control_program"
}
],
"ttl": 0,
"time_range": 1521625823
}
合约交易成功后，合约control_program对应的UTXO将会被所有用户查询到，使用比原链的接口list-unspent-outputs即可查询。
此外，开发者需要存储一下合约UTXO的assetID和program，以便在DAPP的前端页面的config配置文件和bufferserver缓冲服务器中调用。如上所示：
// 储蓄合约
assetID：13016eff73ffb7539a69e122f80f5c1cc94446773ac3f64dec290429f87e73b3
program：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
// 取现合约
assetID：c6b12af8326df37b8d77c77bfa2547e083cbacde15cc48da56d4aa4e4235a3ee
program：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
储蓄分红DAPP架构模型
比原链的DAPP总体框架模型描述了DAPP的大致结构模型，结合储蓄分红合约案例，其具体流程如下：
DAPP前端
储蓄分红合约前端逻辑处理流程大致如下：
1）调用插件
比原的
chrome插件源码位于Bytom-JS-SDK，开发比原DAPP时调用插件的说明可以参考Dapp Developer Guide2）配置合约参数
该
Dapp demo中需要配置实例化的参数为assetDeposited、totalAmountBill、totalAmountCapital、dueBlockHeight、expireBlockHeight、additionalBlockHeight、banker、bankerKey。其前端配置文件为configure.json.jsvar config = { "solonet": { "depositProgram": "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", "profitProgram": "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", "assetDeposited": "3310d9951697418af3cdbe7a9cdde1dc49bb5439503dacb33828d6c9ef5af5a2", "assetBill": "666f298d34806a6db0528c3b3d081bc00fa58aa393e7c42f90d67eb7db2a524f", "totalAmountBill": 1000000000000, "totalAmountCapital": 2000000000000, "dueBlockHeight": 0, "expireBlockHeight": 0, "banker": "0014c800033d5e94de5f22e23a6d3cbeaed87b55bd64", "gas": 0.4 }, "testnet":{ "depositProgram": "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", "profitProgram": "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", "assetDeposited": "00d38a1c946e8cba1a69493240f281cd925002a43b81f516c4391b5fb2ffdacd", "assetBill": "f855baf98778a892bad0371f5afca845191824dc8584585d566fbbc8ef1f304c", "totalAmountBill": 100000000000000, "totalAmountCapital": 200000000000000, "dueBlockHeight": 140506, "expireBlockHeight": 140506, "banker": "00147211ec12410ce8bd0d71cab0a29be3ea61c71eb1", "gas": 0.4 } }3）前端预计算处理
以储蓄合约
FixedLimitCollect为例，前端需要对该合约进行verify语句的预判断逻辑，以防用户输入参数之后执行失败。此外，合约中billAmount of billAsset表示锁定的资产和数量，而billAmount、billAsset和utxohash都是储存在缓冲服务器的数据表里面，因此前端需要调用list-utxo查找与该资产asset和program相关的所有未花费的utxo。 具体可以参考DAPP DEMO前端案例。4）交易组成
比原的交易是多输入多输出的模板结构，如果合约中包含了多个
lock或unlock语句，那么就需要用户构造多输入多输出的交易模板，同时，构造交易还需要根据lock语句或unlock语句来变换。交易构造具体可以参考储蓄合约交易模型和取现合约交易模型的前端源代码。交易
input结构如下：spendUTXOAction(utxohash)表示花费的合约utxo，其中utxohash表示合约UTXO的hash，而spendWalletAction(amount, Constant.assetDeposited)表示用户输入的储蓄或取现的数量（仅包含中需要资产交换的合约中），而资产类型则由前端固定。export function spendUTXOAction(utxohash){ return { "type": "spend_utxo", "output_id": utxohash } } export function spendWalletAction(amount, asset){ return { "amount": amount, "asset": asset, "type": "spend_wallet" } } const input = [] input.push(spendUTXOAction(utxohash)) input.push(spendWalletAction(amount, Constant.assetDeposited))交易
output结构如下：根据合约中
if-else判定逻辑，下面便是储蓄分红合约的output的构造模型。export function controlProgramAction(amount, asset, program){ return { "amount": amount, "asset": asset, "control_program": program, "type": "control_program" } } export function controlAddressAction(amount, asset, address){ return { "amount": amount, "asset": asset, "address": address, "type": "control_address" } } const output = [] if(amountDeposited < billAmount){ output.push(controlProgramAction(amountDeposited, Constant.assetDeposited, Constant.profitProgram)) output.push(controlAddressAction(amountDeposited, billAsset, saver)) output.push(controlProgramAction((billAmount-amountDeposited), billAsset, Constant.depositProgram)) }else{ output.push(controlProgramAction(amountDeposited, Constant.assetDeposited, Constant.profitProgram)) output.push(controlAddressAction(billAmount, billAsset, saver)) }
5）启动前端服务
编译前端命令如下：
npm run build启动之前需要先启动
bufferserver缓冲服务器，然后再启动前端服务，其前端启动命令如下：npm start
DAPP缓冲服务器
缓冲服务器主要是为了在管理合约UTXO层面做一些效率方面的处理，包括了对bycoin服务器是如何同步请求的，此外对DAPP的相关交易记录也进行了存储。具体可以参考一下bufferserver源代码。
1）储蓄分红合约的架构说明如下：
缓冲服务器构成，目前设计了
3张数据表：base、utxo和balance表。其中base表用于初始化该DAPP关注的合约program，即在查找utxo集合的时候，仅仅只需过滤出对应的program和资产即可;utxo表是该DAPP合约的utxo集合，其数据是从bycoin服务器中实时同步过来的，主要是为了提高DAPP的并发性;balance表是为了记录用户参与该合约的交易列表。后端服务由
API进程和同步进程组成，其中API服务进程用于管理对外的用户请求，而同步进程包含了两个方面：一个是从bycoin服务器同步utxo，另一个是则是通过区块链浏览器查询交易状态项目管理员调用
update-base接口更新DAPP关注的合约program和asset。而utxo同步进程会根据base表的记录来定时扫描并更新本地的utxo表中的信息，并且根据超时时间定期解锁被锁定的utxo用户在调用储蓄或取现之前需要查询合约的
utxo是否可用，可用的utxo集合中包含了未确认的utxo。用户在前端在点击储蓄或取现按键的时候，会调用utxo最优匹配算法选择最佳的utxo，然后调用update-utxo接口对该utxo进行锁定，最后就用户就可以通过插件钱包调用bycoin服务器的构建交易接口来创建交易、签名交易和提交交易。倘若所有合约utxo都被锁定了，则会缩短第一个utxo的锁定时间为60s，设置该时间间隔是为了保证未确认的交易被成功验证并生成未确认的utxo。如果该时间间隔并没有产生新的utxo，则认为前面一个用户并没有产生交易，则60s后可以再次花费该utxo。用户发送交易成功后会生成两条
balance记录表，默认状态是失败的，其中交易ID用于向区块链浏览器查询交易状态，如果交易成功则会更新balance的交易状态。此外，前端页面的balance列表表只显示交易成功的记录。
2）编译
bufferserver源代码按照
README安装部署服务需要的软件包Mysql和Redis，然后下载源代码并编译：make all编译完成之后，在
target目录下会生成可执行文件api和updater。3）启动服务
使用
root用户创建数据库和数据表，其命令如下：mysql -u root -p < database/dump.sql修改配置文件
config_local.json，字段说明参考README的config配置参数详解。启动
api和updater服务器，其中api是提供JSON RPC请求的服务进程，updater是提供同步blockcenter和区块链浏览器数据请求的服务进程。./target/api config_local.json ./target/updater config_local.json
