Java chaincode

Note: This guide generally assumes you have followed the Chaincode development environment setup tutorial here.

To get started developing Java chaincode

  1. Ensure you have gradle
  2. Download the binary distribution from http://gradle.org/gradle-download/
  3. Unpack, move to the desired location, and add gradle’s bin directory to your system path
  4. Ensure gradle -v works from the command-line, and shows version 2.12 or greater
  5. Optionally, enable the gradle daemon for faster builds
  6. Ensure you have the Java 1.8 JDK installed. Also ensure Java’s directory is on your path with java -version
  7. Additionally, you will need to have the JAVA HOME variable set to your JDK installation in your system path

  8. From your command line terminal, move to the devenv subdirectory of your workspace environment. Log into a Vagrant terminal by executing the following command:

    vagrant ssh

  9. Build and run the peer process.

    cd $GOPATH/src/github.com/hyperledger/fabric make peer peer node start

  10. The following steps is for deploying chaincode in non-dev mode.

    • Deploy the chaincode,
    peer chaincode deploy -l java -p /opt/gopath/src/github.com/hyperledger/fabric/examples/chaincode/java/SimpleSample -c '{"Args": ["init", "a","100", "b", "200"]}'

6d9a704d95284593fe802a5de89f84e86fb975f00830bc6488713f9441b835cf32d9cd07b087b90e5cb57a88360f90a4de39521a5595545ad689cd64791679e9

    * This command will give the 'name' for this chaincode, and use this value in all the further commands with the -n (name) parameter


    * PS. This may take a few minutes depending on the environment as it deploys the chaincode in the container,
  • Invoke a transfer transaction,
    peer chaincode invoke -l java \
    -n 6d9a704d95284593fe802a5de89f84e86fb975f00830bc6488713f9441b835cf32d9cd07b087b90e5cb57a88360f90a4de39521a5595545ad689cd64791679e9 \
    -c '{"Args": ["transfer", "a", "b", "10"]}'

c7dde1d7-fae5-4b68-9ab1-928d61d1e346

  • Query the values of a and b after the transfer
    peer chaincode query -l java \
    -n 6d9a704d95284593fe802a5de89f84e86fb975f00830bc6488713f9441b835cf32d9cd07b087b90e5cb57a88360f90a4de39521a5595545ad689cd64791679e9 \
    -c '{ "Args": ["query", "a"]}'
    {"Name":"a","Amount":"80"}


    peer chaincode query -l java \
    -n 6d9a704d95284593fe802a5de89f84e86fb975f00830bc6488713f9441b835cf32d9cd07b087b90e5cb57a88360f90a4de39521a5595545ad689cd64791679e9 \
    -c '{ "Args": ["query", "b"]}'
    {"Name":"b","Amount":"220"}

Java chaincode deployment in DEV Mode

  1. Follow the step 1 to 3 as above,
  2. Build and run the peer process
    cd $GOPATH/src/github.com/hyperledger/fabric
    make peer
    peer node start --peer-chaincodedev
  1. Open the second Vagrant terminal and build the Java shim layer and publish it to Local Maven Repo
cd $GOPATH/src/github.com/hyperledger/fabric/core/chaincode/shim/java
gradle -b build.gradle clean
gradle -b build.gradle build
  1. Change to examples folder to build and run,
    cd $GOPATH/src/github.com/hyperledger/fabric/examples/chaincode/java/SimpleSample
    gradle -b build.gradle build

  1. Run the SimpleSample chaincode using the gradle -b build.gradle run

  2. Open the third Vagrant terminal to run init and invoke on the chaincode

    peer chaincode deploy -l java -n SimpleSample -c ‘{“Args”: [“init”, “a”,”100”, “b”, “200”]}’

2016/06/28 19:10:15 Load docker HostConfig: %+v &{[] [] []  [] false map[] [] false [] [] [] [] host    { 0} [] { map[]} false []  0 0 0 false 0    0 0 0 []}
19:10:15.461 [crypto] main -> INFO 002 Log level recognized 'info', set to INFO
SimpleSample

peer chaincode invoke -l java -n SimpleSample -c '{"Args": ["transfer", "a", "b", "10"]}'

2016/06/28 19:11:13 Load docker HostConfig: %+v &{[] [] []  [] false map[] [] false [] [] [] [] host    { 0} [] { map[]} false []  0 0 0 false 0    0 0 0 []}
19:11:13.553 [crypto] main -> INFO 002 Log level recognized 'info', set to INFO
978ff89e-e4ef-43da-a9f8-625f2f6f04e5

peer chaincode query -l java -n SimpleSample -c '{ "Args": ["query", "a"]}'

2016/06/28 19:12:19 Load docker HostConfig: %+v &{[] [] []  [] false map[] [] false [] [] [] [] host    { 0} [] { map[]} false []  0 0 0 false 0    0 0 0 []}
19:12:19.289 [crypto] main -> INFO 002 Log level recognized 'info', set to INFO
{"Name":"a","Amount":"90"}

peer chaincode query -l java -n SimpleSample -c '{"Args": ["query", "b"]}'

2016/06/28 19:12:25 Load docker HostConfig: %+v &{[] [] []  [] false map[] [] false [] [] [] [] host    { 0} [] { map[]} false []  0 0 0 false 0    0 0 0 []}
19:12:25.667 [crypto] main -> INFO 002 Log level recognized 'info', set to INFO
{"Name":"b","Amount":"210"}

Developing new JAVA chaincode

  1. Create a new Java project structure.
  2. Use existing build.grade from any example JAVA Chaincode project like examples/chaincode/java/SimpleSample.
  3. Make your main class extend ChaincodeBase class and implement the following methods from base class.
  4. public String run(ChaincodeStub stub, String function, String[] args)
  5. public String query(ChaincodeStub stub, String function, String[] args)
  6. public String getChaincodeID()
  7. Modify the mainClassName in build.gradle to point to your new class.
  8. Build this project using gradle -b build.gradle build
  9. Run this chaincode after starting a peer in dev-mode as above using gradle -b build.gradle run