SDK修改账本机制
async saveUser (ctx) {const body = ctx.request.body; //获取请求内容console.log(`request`,body.k1) //打印请求k1内容var fabric_client = new Fabric_Client(); //新建一个客户端实例// setup the fabric network//发送消息到order来构建一个新的channel，命名为mychannel，返回一个空对象var channel = fabric_client.newChannel('mychannel');var peer = fabric_client.newPeer('grpc://localhost:7051');//创建一个背书节点channel.addPeer(peer); //将背书节点添加到通道var order = fabric_client.newOrderer('grpc://localhost:7050') //创建一个排序节点channel.addOrderer(order); //将排序节点添加到通道var member_user = null; //设置成员变量为空var store_path = path.join(os.homedir(), '.hfc-key-store'); //设置文件存储路径console.log('Store path:'+store_path); //打印文件存储路径var tx_id = null; //设置空的交易ID// create the key value store as defined in the fabric-client/config/default.json 'key-value-store' settinglet result = await Fabric_Client.newDefaultKeyValueStore({ path: store_path}).then((state_store) => {// assign the store to the fabric clientfabric_client.setStateStore(state_store);var crypto_suite = Fabric_Client.newCryptoSuite();// use the same location for the state store (where the users' certificate are kept)// and the crypto store (where the users' keys are kept)var crypto_store = Fabric_Client.newCryptoKeyStore({path: store_path});crypto_suite.setCryptoKeyStore(crypto_store);fabric_client.setCryptoSuite(crypto_suite);// get the enrolled user from persistence, this user will sign all requestsreturn fabric_client.getUserContext('user1', true);}).then((user_from_store) => {if (user_from_store && user_from_store.isEnrolled()) {console.log('Successfully loaded user1 from persistence');member_user = user_from_store;} else {throw new Error('Failed to get user1.... run registerUser.js');}//获取交易id：基于client对象上分配的用户身份// get a transaction id object based on the current user assigned to fabric clienttx_id = fabric_client.newTransactionID();console.log("Assigning transaction_id: ", tx_id._transaction_id);//构建请求// recordTuna - requires 5 args, ID, vessel, location, timestamp,holder - ex: args: ['10', 'Hound', '-12.021, 28.012', '1504054225', 'Hansel'],// send proposal to endorserconst request = {//targets : --- letting this default to the peers assigned to the channelchaincodeId: 'dateContract10',fcn: 'writeContract',args: [body.k0,body.k1,body.k2,body.k3,body.k4,body.k5,body.k6,body.k7,body.k8],chainId: 'mychannel',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// send the transaction proposal to the peersreturn channel.sendTransactionProposal(request);}).then((results) => { //返回的交易提案和提案响应var proposalResponses = results[0];var proposal = results[1];let isProposalGood = false; // 检查提案响应是否正确if (proposalResponses && proposalResponses[0].response &&proposalResponses[0].response.status === 200) { 如果提案响应、内容、响应代码存在isProposalGood = true; //提案响应正确console.log('Transaction proposal was good');} else {console.error('Transaction proposal was bad');}if (isProposalGood) { //如果响应正确，则打印响应成功代码和信息console.log(util.format('Successfully sent Proposal and received ProposalResponse: Status - %s, message - "%s"',proposalResponses[0].response.status, proposalResponses[0].response.message));//通过交易响应和提案，构建发送到排序服务的请求// build up the request for the orderer to have the transaction committedvar request = {proposalResponses: proposalResponses,proposal: proposal};// set the transaction listener and set a timeout of 30 sec// if the transaction did not get committed within the timeout period,// report a TIMEOUT status//获取事件处理所使用的事务ID字符串 var transaction_id_string = tx_id.getTransactionID(); //Get the transaction ID string to be used by the event processingvar promises = []; //构建promises数组//将交易请求发送给orderer节点，内部调用sendBroadcast(envelope)var sendPromise = channel.sendTransaction(request);//将获得的请求结果添加到数组中 promises.push(sendPromise); //we want the send transaction first, so that we know where to check status// 一旦fabric客户端分配了用户，就得到Evestub。用户必须签名事件中心登记。// get an eventhub once the fabric client has a user assigned. The user// is required bacause the event registration must be signedlet event_hub = fabric_client.newEventHub(); //实例化一个事件中心event_hub.setPeerAddr('grpc://localhost:7053'); //将事件中心绑定到一个新的节点上//设置promise// using resolve the promise so that result status may be processed// under the then clause rather than having the catch clause process// the statuslet txPromise = new Promise((resolve, reject) => { //设置一个promise实例（异步执行）let handle = setTimeout(() => { //设置超时函数event_hub.disconnect();resolve({event_status : 'TIMEOUT'}); //we could use reject(new Error('Trnasaction did not complete within 30 seconds'));//我们也可以使用reject（newError（“Trnasaction在30秒内没有完成”））；}, 3000);event_hub.connect(); //连接事件中心//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event_hub.registerTxEvent(transaction_id_string, (tx, code) => {// this is the callback for transaction event status//这是交易事件状态的回调。// first some clean up of event listener//首先对事件侦听器进行初始化clearTimeout(handle);//解除事件监听event_hub.unregisterTxEvent(transaction_id_string);event_hub.disconnect(); //断开事件中心连接//设置返回代码和交易ID// now let the application know what happenedvar return_status = {event_status : code, tx_id : transaction_id_string}; //如果代码不是有效的if (code !== 'VALID') {console.error('The transaction was invalid, code = ' + code);resolve(return_status); // we could use reject(new Error('Problem with the tranaction, event status ::'+code)); //同理可以使用reject函数} else { //交易已经提交到账本console.log('The transaction has been committed on peer ' + event_hub._ep._endpoint.addr);resolve(return_status);}}, (err) => {//this is the callback if something goes wrong with the event registration or processing如果事件注册或处理出现问题，则此回调reject(new Error('There was a problem with the eventhub ::'+err));});});promises.push(txPromise);//将监听到的信息添加到promisesreturn Promise.all(promises); //返回promises对象} else {//如果出错，打印未能发送提案或收到有效响应。响应空或状态不是200。退出…console.error('Failed to send Proposal or receive valid response. Response null or status is not 200. exiting...');throw new Error('Failed to send Proposal or receive valid response. Response null or status is not 200. exiting...');}}).then((results) => {//打印发送交易背书和事件监听完成console.log('Send transaction promise and event listener promise have completed'); //检查结果第一个参数交易提案是否在在order服务顺序的背书清单中// check the results in the order the promises were added to the promise all listif (results && results[0] && results[0].status === 'SUCCESS') {console.log('Successfully sent transaction to the orderer.');//res.send(tx_id.getTransactionID());//获取交易IDreturn tx_id.getTransactionID();} else {//打印出没有成功提交到排序服务console.error('Failed to order the transaction. Error code: ' + response.status);}//检查交易响应及其返回代码是否有效if(results && results[1] && results[1].event_status === 'VALID') {console.log('Successfully committed the change to the ledger by the peer');//res.send(tx_id.getTransactionID());//打印出交易IDreturn tx_id.getTransactionID();} else { //交易没有成功添加到账本中console.log('Transaction failed to be committed to the ledger due to ::'+results[1].event_status);}}).catch((err) => { //否则出现任何错误，打印调用账本失败console.error('Failed to invoke successfully :: ' + err);});ctx.body = result //获得交易IDconsole.log('result===>',result) 打印出交易ID}}流程：
与前端交互，获取前端输入内容，然后初始化客户端，注册通道、背书节点、排序节点，空的交易ID、设置文件存储路径，然后设置加密模块以及文件路径，通过SDK构建请求，将其发送到背书节点，获得交易提案和交易提案响应，同时检查提案和响应，之后将提案和响应构建请求，发送到排序服务，构建promises数组，将排序结果添加到promises数组中，注册一个事件监听中心，初始化监听后进行监听，之后监听成功则断开监听，获得监听消息和代码后，加入promises数组，否则检查代码，打印错误是否提交到排序服务和账本。最后获得交易ID，打印出交易ID。