The CorDapp Template

When writing a new CorDapp, you’ll generally want to base it on the standard templates:

The Cordapp templates provide the required boilerplate for developing a CorDapp, and allow you to quickly deploy your CorDapp onto a local test network of dummy nodes to test its functionality.

CorDapps can be written in both Java and Kotlin, and will be providing the code in both languages in this tutorial.

Note that there’s no need to download and install Corda itself. Corda V1.0’s required libraries will be downloaded automatically from an online Maven repository.

Downloading the template

To download the template, open a terminal window in the directory where you want to download the CorDapp template, and run the following command:

git clone https://github.com/corda/cordapp-template-java.git ; cd cordapp-template-java

*or*

git clone https://github.com/corda/cordapp-template-kotlin.git ; cd cordapp-template-kotlin

Opening the template in IntelliJ

Once the template is download, open it in IntelliJ by following the instructions here: https://docs.corda.net/tutorial-cordapp.html#opening-the-example-cordapp-in-intellij.

Template structure

The template has a number of files, but we can ignore most of them. To implement our IOU CorDapp in Java, we’ll only need to modify two files. For Kotlin, we’ll simply be modifying the App.kt file:

// 1. The state
src/main/java/com/template/TemplateState.java

// 2. The flow
src/main/java/com/template/TemplateFlow.java

src/main/kotlin/com/template/App.kt

Clean up

To prevent build errors later on, we should delete the following files before we begin:

  • Java:
    • src/main/java/com/template/TemplateClient.java
    • src/test/java/com/template/FlowTests.java
  • Kotlin:
    • src/main/kotlin/com/template/TemplateClient.kt
    • src/test/kotlin/com/template/FlowTests.kt

Progress so far

We now have a template that we can build upon to define our IOU CorDapp. Let’s start by defining the IOUState.