Hyperledger Fabric——balance transfer（五）执行交易

链码安装和实例化之后就可以调用chaincode执行交易，下面分析简单的账户转账操作是如何完成的。

源码分析

1.首先看app.js的路由函数

app.post('/channels/:channelName/chaincodes/:chaincodeName', async function(req, res) {

    var peers = req.body.peers;

    var chaincodeName = req.params.chaincodeName;

    var channelName = req.params.channelName;

    var fcn = req.body.fcn;

    var args = req.body.args;

    // 此处省略了参数校验

    let message = await invoke.invokeChaincode(peers, channelName, chaincodeName, fcn, args, req.username, req.orgname);

    res.send(message);

});

2.接下来找到

var invokeChaincode = async function(peerNames, channelName, chaincodeName, fcn, args, username, org_name) {

    var error_message = null;

    var tx_id_string = null;

    try {

        var client = await helper.getClientForOrg(org_name, username);          // 创建client对象

        var channel = client.getChannel(channelName);                           // 创建channel对象

        // 获取交易id：基于client对象上分配的用户身份（_userContext）

        var tx_id = client.newTransactionID();

        tx_id_string = tx_id.getTransactionID();

        // 请求结构

        var request = {

            targets: peerNames,

            chaincodeId: chaincodeName,

            fcn: fcn,

            args: args,

            chainId: channelName,

            txId: tx_id

        };

        // SDK根据request生成proposal，并调用sendPeersProposal()

        // 将提案发送给背书节点，然后将返回的提案响应连同交易提案一起打包返回给client

        let results = await channel.sendTransactionProposal(request);

        // 返回的交易提案和提案响应

        var proposalResponses = results[0];

        var proposal = results[1];

        // 检查提案响应是否正确

        var all_good = true;

        for (var i in proposalResponses) {

            let one_good = false;

            if (proposalResponses && proposalResponses[i].response &&

                proposalResponses[i].response.status === 200) {

                one_good = true;

                logger.info('invoke chaincode proposal was good');

            } else {

                logger.error('invoke chaincode proposal was bad');

            }

            all_good = all_good & one_good;

        }

        if (all_good) {

            var promises = [];

            // 基于channel的事件中心

            let event_hubs = channel.getChannelEventHubsForOrg();

            #event_hubs.forEach((eh) => {

                #let invokeEventPromise = new Promise((resolve, reject) => {

                    #let event_timeout = setTimeout(() => {

                        let message = 'REQUEST_TIMEOUT:' + eh.getPeerAddr();

                        logger.error(message);

                        eh.disconnect();

                    }, 3000);

                    // 注册交易事件监听，当交易被peer提交到账本中时可以得到反馈

                    #eh.registerTxEvent(tx_id_string, (tx, code, block_num) => {

                        clearTimeout(event_timeout);

                    }, (err) => {

                        clearTimeout(event_timeout);

                        logger.error(err);

                        reject(err);

                    },

                        {unregister: true, disconnect: true}

                    );

                    eh.connect();

                });

                promises.push(invokeEventPromise);

            });

            // 将txID，交易提案和提案响应打包成交易请求

            var orderer_request = {

                txId: tx_id,

                proposalResponses: proposalResponses,

                proposal: proposal

            };

            // 将交易请求发送给orderer节点，内部调用sendBroadcast(envelope)

            var sendPromise = channel.sendTransaction(orderer_request);

            promises.push(sendPromise);

            let results = await Promise.all(promises);

            let response = results.pop();

            if (response.status === 'SUCCESS') {

                logger.info('Successfully sent transaction to the orderer.');

            } else {

                error_message = util.format('Failed to order the transaction. Error code: %s',response.status);

                logger.debug(error_message);

            }

        } else {

            error_message = util.format('Failed to send Proposal and receive all good ProposalResponse');

            logger.debug(error_message);

        }

    } catch (error) {

        logger.error('Failed to invoke due to error: ' + error.stack ? error.stack : error);

        error_message = error.toString();

    }

    if (!error_message) {

        // 返回交易id

        return tx_id_string;

    } else {

        let message = util.format('Failed to invoke chaincode. cause:%s',error_message);

        logger.error(message);

        throw new Error(message);

    }

};

3.如果我们进行简单的转账交易 A->B，则需要调用链码中的move方法，代码如下：

func (t *SimpleChaincode) move(stub shim.ChaincodeStubInterface, args []string) pb.Response {

    // 两个账户A，B

    var A, B string

    // 账户的余额数

    var Aval, Bval int

    // 转移的数值

    var X int

    var err error

    if len(args) != 3 {

        return shim.Error("Incorrect number of arguments. Expecting 4, function followed by 2 names and 1 value")

    }

    A = args[0]

    B = args[1]

    // 获取账户A的值

    Avalbytes, err := stub.GetState(A)

    if err != nil {

        return shim.Error("Failed to get state")

    }

    if Avalbytes == nil {

        return shim.Error("Entity not found")

    }

    Aval, _ = strconv.Atoi(string(Avalbytes))

    // 获取账户B的值

    Bvalbytes, err := stub.GetState(B)

    if err != nil {

        return shim.Error("Failed to get state")

    }

    if Bvalbytes == nil {

        return shim.Error("Entity not found")

    }

    Bval, _ = strconv.Atoi(string(Bvalbytes))

    X, err = strconv.Atoi(args[2])

    if err != nil {

        return shim.Error("Invalid transaction amount, expecting a integer value")

    }

    // 余额转移计算

    Aval = Aval - X

    Bval = Bval + X

    logger.Infof("Aval = %d, Bval = %d\n", Aval, Bval)

    // 将改变后的值写入状态数据库中

    err = stub.PutState(A, []byte(strconv.Itoa(Aval)))

    if err != nil {

        return shim.Error(err.Error())

    }

    err = stub.PutState(B, []byte(strconv.Itoa(Bval)))

    if err != nil {

        return shim.Error(err.Error())

    }

        return shim.Success(nil);

}

测试

交易：

curl -s -X POST \

  http://localhost:4000/channels/mychannel/chaincodes/mycc \

  -H "authorization: Bearer <Token>" \

  -H "content-type: application/json" \

  -d '{

    "peers": ["peer0.org1.example.com","peer1.org1.example.com"],

    "fcn":"move",

    "args":["a","b","10"]

}'

结果：

Transacton ID is 970928c6acbae452a43cbc59e1cb9a558a09c4f354cda0025bd51dafcca3ad96

巴特西

Hyperledger Fabric——balance transfer（五）执行交易

源码分析

测试

最新文章

热门文章