Web3j Open API

Web3j-OpenAPI is a OpenAPI client and server generator from Solidity smart contracts. it provides a way to interact with the Ethereum blockchain via simple and intuitive HTTP requests, abstracting the coding layer. These interactions can be done using :

• Plain HTTP requests
• Via the Swagger-UI, which is generated with every project
• A client application using the webj3-openapi-client implementation

The workflow can be summed in the following steps:

• Writing a Solidity smart contract
• Generating the corresponding OpenAPI project using Web3j-OpenAPI
• Running the generated project as a standalone server
• Sending HTTP requests using Swagger-UI, client application or Curl request.

Getting started with Web3j-OpenAPI

To generate an OpenAPI project using the Web3j-OpenAPI generator, you need to have the Web3j-CLI installed on your machine. It’s easy to do (for Windows instructions head here):

$ curl -L get.web3j.io | sh

Create a Hello World project

To create a base OpenAPI project using a Hello World contract, run the following :

$ web3j openapi new

You can also generate a Web3j-OpenAPI project using the Web3j-OpenAPI-gradle-plugin.

Configure the project

After having the generated project, you can configure your application with the following environment variables:

$ export WEB3J_ENDPOINT=<link_to_your_Ethereum_node>
$ export WEB3J_PRIVATE_KEY=<your_private_key>
$ export WEB3J_OPENAPI_HOST=localhost
$ export WEB3J_OPENAPI_PORT=9090

Run the project

If you aren't using the Web3j-CLI you may run the project using the following Gradle target:

$ cd <project_folder>
$ ./gradlew run

Then, you should be seeing the server logs.

Interact with the project

SwaggerUI

The easiest way to interact with the generated project is via the generated Swagger-UI which can be found on http://<host>:<port>/swagger-ui.

Web3j-OpenAPI client

Also, you can use our client implementation via adding the following dependency to your project:

dependencies {
    implementation "org.web3j.openapi:web3j-openapi-client:4.12.2"
}

Then, within the application:

val service = ClientService("http://localhost:9090")
val app = ClientFactory.create(<AppNameApi>::class.java, service)

// Then you have access to all the API resources
val receipt = app.contracts.contractName.deploy()

println("Deployment receipt: ${receipt.contractAddress}")

// ...

For more information, please refer to the documentation.