Hedera Enterprise

This project provides Java modules to integrate Hedera network smoothless in a Spring Boot or Microprofile (like Quarkus) application. This module is based on the Hedera Java SDK.

Spring Boot support

To use this module, you need to add the following dependency to your project:

<dependency>
    <groupId>com.open-elements.hedera</groupId>
    <artifactId>hedera-spring</artifactId>
    <version>VERSION</version> 
</dependency>

Configuration

To configure the module, you need to add the following properties to your application.properties file:

spring.hedera.accountId=0.0.53854625
spring.hedera.privateKey=2130020100312346052b8104400304220420c236508c429395a8180b1230f436d389adc5afaa9145456783b57b2045c6cc37
spring.hedera.network=testnet

The account information (accountId, privateKey, publicKey) can all be found at the Hedera portal for a testnet or previewnet account. Today only the "DER Encoded Private Key" of the "ECDSA" key type is supported for the spring.hedera.privateKey property.

The 2 properties spring.hedera.accountId and spring.hedera.privateKey define the so called "operation account". The operational account is used as the account that sends all transactions against the Hedera network.

Usage

To use the module, you need to add the @EnableHedera annotation to your Spring Boot application class.

import com.open.elements.spring.hedera.EnableHedera;

@SpringBootApplication
@EnableHedera
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

Once that is done you can for example autowire the FileClient class and call the methods to interact with the Hedera network.

@Service
public class HederaAccountService {

    @Autowired
    private FileClient fileClient;

    public String readFile(String id) {
        FileId fileId = FileId.of(id);
        byte[] content = fileClient.readFile(fileId);
        return new String(content);
    }
}

All APIs of the client are synchronous and return the result of the operation. For asynchronous operations, you can easily wrap calls by use the @Async annotation of spring.

Hedera Spring Sample

A sample application that uses the Hedera Spring module can be found in the hedera-spring-sample module. The sample application is a simple Spring Boot application that reads has a REST endpoint at localhost:8080/ and shows the hbar balance of the account 0.0.100. To use the application, you need to have created a Hedera testnet account at the Hedera portal. The account information can be added to the application.properties file in the hedera-spring-sample module:

spring.hedera.accountId=0.0.3447271
spring.hedera.privateKey=2130020100312346052b8104400304220420c236508c429395a8180b1230f436d389adc5afaa9145456783b57b2045c6cc37

Alternatively, you can provide the account information as environment variables:

export HEDERA_ACCOUNT_ID=0.0.3447271
export HEDERA_PRIVATE_KEY=2130020100312346052b8104400304220420c236508c429395a8180b1230f436d389adc5afaa9145456783b57b2045c6cc37

Microservice support

The support for Microprofile is still in development and can not be used yet.

Managed services

The module provides a set of managed services that can be used to interact with the Hedera network. The following services are available in spring and microprofile:

• com.openelements.hedera.base.AccountClient: to interact with Hedera accounts
• com.openelements.hedera.base.FileClient: to interact with Hedera files
• com.openelements.hedera.base.SmartContractClient: to interact with Hedera smart contracts
• com.openelements.hedera.base.ContractVerificationClient: to verify smart contracts
• com.openelements.hedera.base.NftClient: to interact with Hedera NFTs
• com.openelements.hedera.base.NftRepository: to query NFTs

Next to that the following low-level services are available:

• com.openelements.hedera.base.protocol.ProtocolLayerClient: to interact with the Hedera protocol layer
• com.openelements.hedera.base.mirrornode.MirrorNodeClient: to query the Hedera mirror node

Built the project

The project is based on Maven. To build the project, you can use the following command:

./mvnw verify

The tests in the project are working against the Hedera testnet. To run the tests, you need to provide the account id and the "DER Encoded Private Key" of the "ECDSA" testnet account. That information can be provided as environemt variables:

export HEDERA_ACCOUNT_ID=0.0.3447271
export HEDERA_PRIVATE_KEY=2130020100312346052b8104400304220420c236508c429395a8180b1230f436d389adc5afaa9145456783b57b2045c6cc37

As an alternative you can define the information in a .env file in each sub-module that contains tests. The file should look like this:

spring.hedera.accountId=0.0.3447271
spring.hedera.privateKey=2130020100312346052b8104400304220420c236508c429395a8180b1230f436d389adc5afaa9145456783b57b2045c6cc37

Create a release

The project is using the JReleaser Maven plugin to create and publish releases. To use the plugin, you need to provide the following environment variables:

JRELEASER_GITHUB_TOKEN=your_secret_github_token
JRELEASER_GPG_SECRET_KEY=your_secret_key
JRELEASER_GPG_PASSPHRASE=your_secret_passphrase
JRELEASER_GPG_PUBLIC_KEY=yout_public_key
JRELEASER_NEXUS2_MAVEN_CENTRAL_USERNAME=your_maven_central_username
JRELEASER_NEXUS2_MAVEN_CENTRAL_TOKEN=your_secret_maven_central_token

How that environment variables are defined can be found in the JReleaser documentation and this blog post.

On a unix based system the environment variables can be defined in the .env file in the root of the project. That file is added to the .gitignore file and can not be committed to the repository. If you have created the .env file, you can simply load the environment variables with the following command:

export $(grep -v '^#' .env | xargs)

To create a release, you can use the following commands:

./mvnw versions:set -DnewVersion=0.1.0
./mvnw clean verify
git commit -am "Version 0.1.0"
git push
./mvnw -Ppublication deploy
./mvnw -Ppublication jreleaser:full-release
./mvnw versions:set -DnewVersion=0.2.0-SNAPSHOT
git commit -am "Version 0.2.0-SNAPSHOT"
git push

This will create a release on GitHub and publish the artifacts to Maven Central.

License

This project is licensed under the Apache License 2.0 - see the LICENSE file for details.