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Set up and initialize the channel, install and instantiate chaincode, and perform invoke and query on your blockchain network

Blockchain is a shared, immutable ledger for recording the history of transactions. The Linux Foundation’s Hyperledger Fabric, the software implementation of blockchain IBM is committed to, is a permissioned network. Hyperledger Fabric is a platform for distributed ledger solutions underpinned by a modular architecture delivering high degrees of confidentiality, resiliency, flexibility and scalability.

In a Blockchain solution, the Blockchain network works as a back-end with an application front-end to communicate with the network using a SDK. To set up the communication between front-end and back-end, Hyperledger Fabric community offers a number of SDKs for a wide variety of programming languages like the NodeJS SDK and Java SDK. This code pattern explains the methodology to create, deploy and test the blockchain network using Hyperledger Fabric SDK Java.

It would be helpful for the Java developers, who started to look into Hyperledger Fabric platform and would like to use Fabric SDK Java for their projects. The SDK helps facilitate Java applications to manage the lifecycle of Hyperledger channels and user chaincode. The SDK also provides a means to execute user chaincode, query blocks and transactions on the channel, and monitor events on the channel. This code pattern will help to get the process started to build a Hyperledger Fabric v1.4.1 Java application.

When the reader has completed this pattern, they will understand how to create, deploy and test a blockchain network using Hyperledger Fabric SDK Java. This pattern will provision a Hyperledger Fabric 1.4.1 network consisting of two organizations, each maintaining two peer node, two certificate authorities (ca) for each organization and a solo ordering service. The following aspects will be demonstrated in this code pattern:

• Create and initialize channel
• Install and instantiate chain code
• Register and enroll the users
• Perform invoke and query on the blockchain network.

Note: This code pattern builds a Hyperledger Fabric 1.4.1 network and uses Hyperledger Fabric SDK java 1.4.1 .

1. Generate the artifacts using cryptogen and configtx for peers and channel in network. Currently these are already generated and provided in the code repository to use as-is.
2. Build the network using docker-compose and the generated artifacts.
3. Use Hyperledger Fabric Java SDK APIs to work with and manage the network.
   • Create and initialize the channel
   • Install and instantiate the chaincode
   • Register and enroll the users
   • Perform invoke and query to test the network

• Hyperledger Fabric: Hyperledger Fabric is a platform for distributed ledger solutions underpinned by a modular architecture delivering high degrees of confidentiality, resiliency, flexibility and scalability.

• Docker: Docker is an open platform for developers and sysadmins to build, ship, and run distributed applications.

• Hyperledger Fabric Java SDK

• Blockchain: A blockchain is a digitized, decentralized, public ledger of all transactions in a network.

• Java: Java is a general-purpose computer-programming language that is concurrent, class-based and object-oriented.

]

• Docker
• Docker Compose
• Git Client - needed for clone commands
• Maven - needed to build the client. Maven is a build automation tool used primarily for Java projects. Maven addresses two aspects of building software: first, it describes how software is built, and second, it describes its dependencies.

Follow these steps to setup and run this code pattern.

1. Setup the Blockchain Network
2. Build the client based on Fabric Java SDK
3. Create and Initialize the channel
4. Deploy and Instantiate the chaincode
5. Register and enroll users
6. Perform Invoke and Query on network

Clone this repo using the following command.

$ git clone https://github.com/IBM/blockchain-application-using-fabric-java-sdk

To build the blockchain network, the first step is to generate artifacts for peers and channels using cryptogen and configtx. The utilities used and steps to generate artifacts are explainedhere. In this pattern all required artifacts for the peers and channel of the network are already generated and provided to use as-is. Artifacts can be located at:

network_resources/crypto-confignetwork_resources/config

The automated scripts to build the network are provided undernetwork directory. Thenetwork/docker-compose.yaml file defines the blockchain network topology. This pattern provisions a Hyperledger Fabric 1.4.1 network consisting of two organizations, each maintaining two peer node, two certificate authorities for each organization and a solo ordering service. Need to run the script as follows to build the network.

Note: Please clean up the old docker images (if any) from your environment otherwise you may get errors while setting up network.

cd networkchmod +x build.sh./build.sh

To stop the running network, run the following script.

cd networkchmod +x stop.sh./stop.sh

To delete the network completely, following script need to execute.

cd networkchmod +x teardown.sh./teardown.sh

The previous step creates all required docker images with the appropriate configuration.

Java Client

• The java client sources are present in the folderjava of the repo.
• Check your environment before executing the next step. Make sure, you are able to runmvn commands properly.

  Ifmvn commands fails, please refer toPre-requisites to install maven.

To work with the deployed network using Hyperledger Fabric SDK java 1.4.1, perform the following steps.

• Open a command terminal and navigate to thejava directory in the repo. Run the commandmvn install.

  cd ../javamvn install

• A jar fileblockchain-java-sdk-0.0.1-SNAPSHOT-jar-with-dependencies.jar is built and can be found under thetarget folder. This jar can be renamed toblockchain-client.jar to keep the name short.

  cd targetcp blockchain-java-sdk-0.0.1-SNAPSHOT-jar-with-dependencies.jar blockchain-client.jar

• Copy this built jar intonetwork_resources directory. This is required as the java code can access required artifacts during execution.

  cp blockchain-client.jar ../../network_resources

In this code pattern, we create one channelmychannel which is joined by all four peers. The java source code can be seen atsrc/main/java/org/example/network/CreateChannel.java. To create and initialize the channel, run the following command.

cd ../../network_resourcesjava -cp blockchain-client.jar org.example.network.CreateChannel

Output:

   INFO: Deleting - users   Apr 20, 2018 5:11:45 PM org.example.network.CreateChannel main   INFO: Channel created mychannel   Apr 20, 2018 5:11:45 PM org.example.network.CreateChannel main   INFO: peer0.org1.example.com at grpc://localhost:7051   Apr 20, 2018 5:11:45 PM org.example.network.CreateChannel main   INFO: peer1.org1.example.com at grpc://localhost:7056   Apr 20, 2018 5:11:45 PM org.example.network.CreateChannel main   INFO: peer0.org2.example.com at grpc://localhost:8051   Apr 20, 2018 5:11:45 PM org.example.network.CreateChannel main   INFO: peer1.org2.example.com at grpc://localhost:8056

This code pattern uses a sample chaincodefabcar to demo the usage of Hyperledger Fabric SDK Java APIs. To deploy and instantiate the chaincode, execute the following command.

java -cp blockchain-client.jar org.example.network.DeployInstantiateChaincode

Output:

   INFO: Deploying chaincode fabcar using Fabric client Org1MSP admin   Apr 23, 2018 10:25:22 AM org.example.network.DeployInstantiateChaincode main   INFO: fabcar- Chain code deployment SUCCESS   Apr 23, 2018 10:25:22 AM org.example.network.DeployInstantiateChaincode main   INFO: fabcar- Chain code deployment SUCCESS   Apr 23, 2018 10:25:22 AM org.example.client.FabricClient deployChainCode   INFO: Deploying chaincode fabcar using Fabric client Org2MSP admin   Apr 23, 2018 10:25:22 AM org.example.network.DeployInstantiateChaincode main   INFO: fabcar- Chain code deployment SUCCESS   Apr 23, 2018 10:25:22 AM org.example.network.DeployInstantiateChaincode main   INFO: fabcar- Chain code deployment SUCCESS   Apr 23, 2018 10:25:22 AM org.example.client.ChannelClient instantiateChainCode   INFO: Instantiate proposal request fabcar on channel mychannel with Fabric client Org2MSP admin   Apr 23, 2018 10:25:22 AM org.example.client.ChannelClient instantiateChainCode   INFO: Instantiating Chaincode ID fabcar on channel mychannel   Apr 23, 2018 10:25:25 AM org.example.client.ChannelClient instantiateChainCode   INFO: Chaincode fabcar on channel mychannel instantiation java.util.concurrent.CompletableFuture@723ca036[Not completed]   Apr 23, 2018 10:25:25 AM org.example.network.DeployInstantiateChaincode main   INFO: fabcar- Chain code instantiation SUCCESS   Apr 23, 2018 10:25:25 AM org.example.network.DeployInstantiateChaincode main   INFO: fabcar- Chain code instantiation SUCCESS   Apr 23, 2018 10:25:25 AM org.example.network.DeployInstantiateChaincode main   INFO: fabcar- Chain code instantiation SUCCESS   Apr 23, 2018 10:25:25 AM org.example.network.DeployInstantiateChaincode main   INFO: fabcar- Chain code instantiation SUCCESS

Note: The chaincode fabcar.go was taken from the fabric samples available at -https://github.com/hyperledger/fabric-samples/tree/release-1.4/chaincode/fabcar/go.

A new user can be registered and enrolled to an MSP. Execute the below command to register a new user and enroll to Org1MSP.

java -cp blockchain-client.jar org.example.user.RegisterEnrollUser

Output:

   INFO: Deleting - users   log4j:WARN No appenders could be found for logger (org.hyperledger.fabric.sdk.helper.Config).   log4j:WARN Please initialize the log4j system properly.   log4j:WARN See https://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.   Apr 23, 2018 10:26:35 AM org.example.client.CAClient enrollAdminUser   INFO: CA -http://localhost:7054 Enrolled Admin.   Apr 23, 2018 10:26:35 AM org.example.client.CAClient registerUser   INFO: CA -http://localhost:7054 Registered User - user1524459395783   Apr 23, 2018 10:26:36 AM org.example.client.CAClient enrollUser   INFO: CA -http://localhost:7054 Enrolled User - user1524459395783

Blockchain network has been setup completely and is ready to use. Now we can test the network by performing invoke and query on the network. Thefabcar chaincode allows us to create a new asset which is a car. For test purpose, invoke operation is performed to create a new asset in the network and query operation is performed to list the asset of the network. Perform the following steps to check the same.

java -cp blockchain-client.jar org.example.chaincode.invocation.InvokeChaincode

Output:

  INFO: CA -http://localhost:7054 Enrolled Admin.  Apr 20, 2018 5:13:04 PM org.example.client.ChannelClient sendTransactionProposal  INFO: Sending transaction proposal on channel mychannel  Apr 20, 2018 5:13:04 PM org.example.client.ChannelClient sendTransactionProposal  INFO: Transaction proposal on channel mychannel OK SUCCESS with transaction  id:a298b9e27bdb0b6ca18b19f9c78a5371fb4d9b8dd199927baf37379537ca0d0f  Apr 20, 2018 5:13:04 PM org.example.client.ChannelClient sendTransactionProposal  INFO:  Apr 20, 2018 5:13:04 PM org.example.client.ChannelClient sendTransactionProposal  INFO: java.util.concurrent.CompletableFuture@22f31dec[Not completed]  Apr 20, 2018 5:13:04 PM org.example.chaincode.invocation.InvokeChaincode main  INFO: Invoked createCar on fabcar. Status - SUCCESS

java -cp blockchain-client.jar org.example.chaincode.invocation.QueryChaincode

Output:

    Apr 20, 2018 5:13:28 PM org.example.client.CAClient enrollAdminUser    INFO: CA -http://localhost:7054 Enrolled Admin.    Apr 20, 2018 5:13:29 PM org.example.chaincode.invocation.QueryChaincode main    INFO:Querying for all cars ...    Apr 20, 2018 5:13:29 PM org.example.client.ChannelClient queryByChainCode    INFO: Querying queryAllCars on channel mychannel    Apr 20, 2018 5:13:29 PM org.example.chaincode.invocation.QueryChaincode main    INFO:[{"Key":"CAR1", "Record":{"make":"Chevy","model":"Volt","colour":"Red","owner":"Nick"}}]    Apr 20, 2018 5:13:39 PM org.example.chaincode.invocation.QueryChaincode main    INFO:Querying for a car - CAR1    Apr 20, 2018 5:13:39 PM org.example.client.ChannelClient queryByChainCode    INFO: Querying queryCar on channel mychannel    Apr 20, 2018 5:13:39 PM org.example.chaincode.invocation.QueryChaincode main    INFO:{"make":"Chevy","model":"Volt","colour":"Red","owner":"Nick"}

See DEBUGGING.md.

This code pattern is licensed under the Apache Software License, Version 2. Separate third party code objects invoked within this code pattern are licensed by their respective providers pursuant to their own separate licenses. Contributions are subject to theDeveloper Certificate of Origin, Version 1.1 (DCO) and theApache Software License, Version 2.

Apache Software License (ASL) FAQ