Hyperledger Fabric REST Integration

Description:-

This artifact provides a mechanism to invoke and query fabric chaincode using a REST-based API interface.
Additionally, it can also invoke chaincode using a asynchronous method and can publish chaincode events to Kafka/Event-Hub topics.

Key Feature:-

1. Invoke Chaincode with REST.
   
2. Query Chaincode with REST.
   
3. Invoke Chaincode with Kafka/Event-Hub.
   
4. Publish chaincode events from multiple channels to Kafka/Event-Hub.
   

Prerequisites:-

1. Fabric 2.x network.
   
2. Connection Profile YAML file.
   
3. Wallet (.id) file.
   
4. Java and Maven is installed.
5. (Optional) Kafka/Event-Hub configuration for invoking chaincode asynchronously.
   
6. (Optional) Kafka/Event-Hub configuration for publishing chaincode events.
   

Running Locally:-

1. Download/Clone the repository and build the project using mvn clean install
2. Create a folder wallet in the root directory of the project.
   
3. If using fabric-getting-started script, note the path to CA Pem file for Org1.
   Usually located in fabric-getting-started/test-network/organizations/peerOrganizations/org1.example.com/ca folder.
4. Open EnrollAdmin.java and set the pemFilePath variable with value noted above and run. This will create admin.id in the wallet folder.
5. Open RegisterUser and set the pemFilePath variable with value noted above and run. This will create clientUser.id in the wallet folder.
6. Add the connection-org1.yaml file, located at fabric-getting-started/test-network/organizations/peerOrganizations/org1.example.com to the wallet folder.
   
7. Make sure the Peer URL and CA URL in connection-org1.yaml are reachable.
   If using fabric-getting-started, change the peer URL in connection-org1.yaml to peer0.org1.example.com:7051 and CA URL to ca-org1:7054.
8. Run, hlf.java.rest.client.FabricClientBootstrap java file or jar file.
9. You can also run as container using docker-compose up.
   If the fabric network is running local, make sure the docker-compose.yml file is configured to use the correct network.
   

networks:
  default:
    external:
      name: <fabric's network>

Event-driven Design

Asynchronous Integration to invoke chaincode

This component supports event-based architecture by consuming transactions through Kafka & Azure EventHub. To configure it, use the below configuration in the application.yml file.

kafka:
  integration-points:
  -
    brokerHost: <Hostname1 with Port>
    groupId: <Group ID>
    topic: <Topic Name>
  -
    brokerHost: <Hostname2 with Port>
    groupId: <Group ID>
    topic: <Topic Name>
    # For Azure EventHub
    jaasConfig: org.apache.kafka.common.security.plain.PlainLoginModule required username="$ConnectionString" password="Endpoint=sb://<Hostname>/;SharedAccessKeyName=<key-name>;SharedAccessKey=<key-value>";
    # For SOX compliant Kafka Clusters
    ssl-enabled: true
    security-protocol: SSL
    ssl-keystore-location: <YOUR_SSL_KEYSTORE_PATH>
    ssl-keystore-password: <YOUR_SSL_PASSWORDH>
    ssl-truststore-location: <YOUR_SSL_TRUSTSTORE_PATH>
    ssl-truststore-password: <YOUR_SSL_TRUSTSTORE_PASSWORD>
    ssl-key-password: <YOUR_SSL_KEY_PASSWORD>

The component accepts JSON payload and 3 headers to invoke the chaincode. Please find below the keys for the headers:-

1. channel_name
2. function_name
3. chaincode_name

Capture Chaincode events:-

This component supports capturing chaincode events and publish it to Kafka or Azure EventHub. This can be useful for integrating with offchain DB. To configure it, use the below configuration in the application.yml file.

fabric:
  events:
    enabled: true
    chaincode: mychannel1,mychannel2  #Comma-separated list for listening to events from multiple channels 
kafka:
  event-listener:
    brokerHost: <Hostname with Port>
    topic: <Topic Name>
    # For Azure EventHub
    jaasConfig: org.apache.kafka.common.security.plain.PlainLoginModule required username="$ConnectionString" password="Endpoint=sb://<Hostname>/;SharedAccessKeyName=<key-name>;SharedAccessKey=<key-value>";
    # For SOX compliant Kafka Clusters
    ssl-enabled: true
    security-protocol: SSL
    ssl-keystore-location: <YOUR_SSL_KEYSTORE_PATH>
    ssl-keystore-password: <YOUR_SSL_PASSWORDH>
    ssl-truststore-location: <YOUR_SSL_TRUSTSTORE_PATH>
    ssl-truststore-password: <YOUR_SSL_TRUSTSTORE_PASSWORD>
    ssl-key-password: <YOUR_SSL_KEY_PASSWORD>

The component will send the same JSON payload sent by the chaincode and add the following headers.

1. fabric_tx_id
2. event_name
3. channel_name
4. event_type (value: chaincode_event)

Capture Block events:-

This component supports capturing block events and publish it to Kafka or Azure EventHub. This can be useful for integrating with offchain DB where adding events to chaincode is not possible (for ex - Food-Trust anchor channel). To configure it, use the below configuration in the application.yml file.

fabric:
  events:
    enabled: true
    block: mychannel1,mychannel2  #Comma-separated list for listening to events from multiple channels 
kafka:
  event-listener:
    brokerHost: <Hostname with Port>
    topic: <Topic Name>
    # For Azure EventHub
    jaasConfig: org.apache.kafka.common.security.plain.PlainLoginModule required username="$ConnectionString" password="Endpoint=sb://<Hostname>/;SharedAccessKeyName=<key-name>;SharedAccessKey=<key-value>";
    # For SOX compliant Kafka Clusters
    ssl-enabled: true
    security-protocol: SSL
    ssl-keystore-location: <YOUR_SSL_KEYSTORE_PATH>
    ssl-keystore-password: <YOUR_SSL_PASSWORDH>
    ssl-truststore-location: <YOUR_SSL_TRUSTSTORE_PATH>
    ssl-truststore-password: <YOUR_SSL_TRUSTSTORE_PASSWORD>
    ssl-key-password: <YOUR_SSL_KEY_PASSWORD>

The component will send the same JSON payload sent by the chaincode and add the following headers.

1. fabric_tx_id
2. channel_name
3. chaincode name
4. function_name
5. event_type (value: block_event)