如何监听Fabric链码的事件 | 学习软件编程

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//deleteKajmak method definition
func (s *SmartContract) deleteKajmak(APIstub shim.ChaincodeStubInterface, args []string) sc.Response {
     if len(args) != 8 {
          return shim.Error("Incorrect number of arguments.       Expecting 8")
     }
     err := APIstub.DelState(args[0])
     if (err != nil) {
          return shim.Error(fmt.Sprintf("Failed to delete kajmak: %s", args[0]))
     }
     fmt.Printf("- deleteKajmak:\n%s\n", args[0])
     return shim.Success(nil);
}

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SetEvent(name string, payload []byte) error

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eventPayload := "Kajmak with ID " + args[0] + " whose owner is " + args[2] + " was deleted because it has expired on date " + args[7]
payloadAsBytes := []byte(eventPayload)

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eventErr := APIstub.SetEvent("deleteEvent",payloadAsBytes)
if (eventErr != nil) {
     return shim.Error(fmt.Sprintf("Failed to emit event"))
}

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//deleteKajmak method definition
func (s *SmartContract) deleteKajmak(APIstub shim.ChaincodeStubInterface, args []string) sc.Response {
     if len(args) != 8 {
          return shim.Error("Incorrect number of arguments. Expecting 8")
     }
     err := APIstub.DelState(args[0])
     if (err != nil) {
          return shim.Error(fmt.Sprintf("Failed to delete kajmak: %s", args[0]))
     }
     eventPayload := "Kajmak with ID " + args[0] + " whose owner is " + args[2] + " was deleted because it has expired on date " + args[7]
     payloadAsBytes := []byte(eventPayload)
     eventErr := APIstub.SetEvent("deleteEvent",payloadAsBytes)
     if (eventErr != nil) {
          return shim.Error(fmt.Sprintf("Failed to emit event"))
     }
     fmt.Printf("- deleteKajmak:\n%s\n", args[0])
     return shim.Success(nil);
}

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var deleteKajmak = async function(username,userOrg,kajmakData) {
     var error_message = null;
     try {
          var array = kajmakData.split("-");
          console.log(array);
          var key = array[0]
          var name = array[1]
          var owner = array[2]
          var animal = array[3]
          var location = array[4]
          var quantity = array[5]
          var productionDate = array[6]
          var expirationDate = array[7]
          var client = await getClientForOrg(userOrg,username);
          logger.debug('Successfully got the fabric client for the  organization "%s"', userOrg);
          var channel = client.getChannel('mychannel');
          if(!channel) {
               let message = util.format('Channel %s was not defined in the connection profile', channelName);
               logger.error(message);
               throw new Error(message);
          }
          var targets = null;
          if(userOrg == "Org1") {
               targets = ['peer0.org1.example.com'];
          } else if(userOrg == "Org2") {
               targets = ['peer0.org2.example.com'];
          }
          var tx_id = client.newTransactionID();
          console.log("Assigning transaction_id: ", tx_id._transaction_id);
          var tx_id_string = tx_id.getTransactionID();
          var request = {
               targets: targets,
               chaincodeId: 'kajmak-app',
               fcn: 'deleteKajmak',
               args: [key, name, owner, animal, location, quantity, productionDate, expirationDate],
               chainId: channel,
               txId: tx_id
          };
          let results = await channel.sendTransactionProposal(request);
          var proposalResponses = results[0];
          var proposal = results[1];
          let isProposalGood = false;
          if (proposalResponses && proposalResponses[0].response && proposalResponses[0].response.status === 200) {
               isProposalGood = true;
               console.log('Transaction proposal was good');
          } else {
               console.error('Transaction proposal was bad');
          }
          if (isProposalGood) {
               console.log(util.format('Successfully sent Proposal and received ProposalResponse: Status - %s, message - "%s"', proposalResponses[0].response.status, proposalResponses[0].response.message));
               var promises = [];
               var requestMain = {
                    txId: tx_id,
                    proposalResponses: proposalResponses,
                    proposal: proposal
               };
               var sendPromise = channel.sendTransaction(requestMain);
               promises.push(sendPromise);
               let results = await Promise.all(promises);
logger.debug(util.format('------->>> R E S P O N S E : %j', results));
               let response = results.pop(); //  orderer results are last in the results
               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 delete kajmak with error: %s', error.toString());
     }
};

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var deleteKajmak = async function(username,userOrg,kajmakData) {
     var error_message = null;
     try {
          var array = kajmakData.split("-");
          console.log(array);
          var key = array[0]
          var name = array[1]
          var owner = array[2]
          var animal = array[3]
          var location = array[4]
          var quantity = array[5]
          var productionDate = array[6]
          var expirationDate = array[7]
          var client = await getClientForOrg(userOrg,username);
          logger.debug('Successfully got the fabric client for the organization "%s"', userOrg);
          var channel = client.getChannel('mychannel');
          if(!channel) {
               let message = util.format('Channel %s was not defined in the connection profile', channelName);
               logger.error(message);
               throw new Error(message);
          }
          var targets = null;
          if(userOrg == "Org1") {
               targets = ['peer0.org1.example.com'];
          } else if(userOrg == "Org2") {
               targets = ['peer0.org2.example.com'];
          }
          var tx_id = client.newTransactionID();
          console.log("Assigning transaction_id: ", tx_id._transaction_id);
          var tx_id_string = tx_id.getTransactionID();
          var request = {
               targets: targets,
               chaincodeId: 'kajmak-app',
               fcn: 'deleteKajmak',
               args: [key, name, owner, animal, location, quantity, productionDate, expirationDate],
               chainId: channel,
               txId: tx_id
          };
          let results = await channel.sendTransactionProposal(request);
          var proposalResponses = results[0];
          var proposal = results[1];
          let isProposalGood = false;
          if (proposalResponses && proposalResponses[0].response && proposalResponses[0].response.status === 200) {
               isProposalGood = true;
               console.log('Transaction proposal was good');
          } else {
               console.error('Transaction proposal was bad');
          }
          if (isProposalGood) {
               console.log(util.format('Successfully sent Proposal and received ProposalResponse: Status - %s, message - "%s"', proposalResponses[0].response.status, proposalResponses[0].response.message));
               var promises = [];
               let event_hubs = channel.getChannelEventHubsForOrg();
               event_hubs.forEach((eh) => {
               logger.debug('invokeDeleteKajmakEventPromise - setting up event');
               console.log(eh);
               let invokeEventPromise = new Promise((resolve, reject) => {
                    let regid = null;
                    let event_timeout = setTimeout(() => {
                    if(regid) {
                    let message = 'REQUEST_TIMEOUT:' + eh.getPeerAddr();
                    logger.error(message);
                    eh.unregisterChaincodeEvent(regid);
                    eh.disconnect();
                    }
                    reject();
                    }, 20000);
               regid = eh.registerChaincodeEvent('kajmak-app', 'deleteEvent',(event, block_num, txnid, status) => {
               console.log('Successfully got a chaincode event with transid:'+ txnid + ' with status:'+status);
               let event_payload = event.payload.toString();
               console.log(event_payload);
               if(event_payload.indexOf(array[0]) > -1) {
                    clearTimeout(event_timeout);
                    //Chaincode event listeners are meant to run continuously
                    //Therefore the default to automatically unregister is false
                    //So in this case we want to shutdown the event listener once
                    // we see the event with the correct payload
                    eh.unregisterChaincodeEvent(regid);
                    console.log('Successfully received the chaincode event on block number '+ block_num);
                    resolve(event_payload);
               } else {
                    console.log('Successfully got chaincode event ... just not the one we are looking for on block number '+ block_num);
               }
               }, (err) => {
               clearTimeout(event_timeout);
               logger.error(err);
               reject(err);
               }
               //no options specified
               //startBlock will default to latest
               //endBlock will default to MAX
               //unregister will default to false
               //disconnect will default to false
               );
               eh.connect(true);
          });
          promises.push(invokeEventPromise);
          console.log(eh.isconnected());
          });
     
          var requestMain = {
               txId: tx_id,
               proposalResponses: proposalResponses,
               proposal: proposal
          };
          var sendPromise = channel.sendTransaction(requestMain);
          promises.push(sendPromise);
          let results = await Promise.all(promises);
          logger.debug(util.format('------->>> R E S P O N S E : %j', results));
          let response = results.pop(); //  orderer results are last in the results
          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);
          }
     
          // now see what each of the event hubs reported
          for(let i in results) {
               let event_hub_result = results[i];
               let event_hub = event_hubs[i];
               logger.debug('Event results for event hub :%s',event_hub.getPeerAddr());
               if(typeof event_hub_result === 'string') {
                    logger.debug(event_hub_result);
                    var rezultat = {event_payload : event_hub_result};
                    return rezultat;
               } else {
                    if(!error_message) error_message = event_hub_result.toString();
                    logger.debug(event_hub_result.toString());
               }
          }
     } else {
          error_message = util.format('Failed to send Proposal and receive all good ProposalResponse');
          logger.debug(error_message);
     }
} catch(error) {
     logger.error('Failed to delete kajmak with error: %s', error.toString());
}
};

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