A Comprehensive Guide to Creating Your First CorDapp

19 June 2020
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Corda is an open-source Blockchain platform that allows us to design and develop the applications in an open environment. The main purpose of the CorDapp is to allow nodes to reach common agreement on the updates to the distributed ledger.

Blockchain is a distributed ledger technology that is initially created for direct, valuable transactions without the need for an intermediary. When coupled with Blockchain technology and smart contracts, Corda can help cut down the record-keeping cost while streamlining the business operations.

Why Corda?

The traditional Blockchain platforms have a drawback of lacking privacy and decisiveness. The Corda platform was developed to address the shortcomings, enabling private transactions with instant finality. Corda is compatible with any JVM language, and it is written in Kotlin.

Here are a few benefits of Corda that would help you understand the benefits of using Corda for App development:

1. Privacy

In comparison to permission-less Blockchain networks, the transaction data between different parties on Corda is private. This also gives you a single shared ledger, as when one transaction is validated, the record becomes permanent and secure.

2. Flexible and Agile

Corda is a flexible, agile platform that scales to meet the required business needs. You can easily transfer between Corda to Corda enterprise and grow as your business requirements evolve.

3. Interoperability

Interoperability is an important part of the business that allows you to transact directly, seamlessly and securely. Due to this added benefit of Corda, all of the versions of Corda are free and commercial and can also interoperate with each other on the Corda network.

4. Open design

Openness is one of the major benefits of Corda as it is an open-source platform. This advantage is rooted in the R3’s heritage and benefits a collaborative group of firms that work together to deliver Blockchain.

5. Open development

Corda is backed-up by a robust community of the developers that work together for the enhancements, functionality, and many other added features.

Developing Apps using Corda- Use Case

In a world full of permission-less Blockchain platforms, where data is available to all the parties, Corda’s strict privacy model allows businesses to transact securely and seamlessly.

Here are a few CorDapp components that would help you to better understand this platform:

CorDapp Components

CorDapp takes the form of a set of JAR files containing class definitions that are written in Java and/or Kotlin.

These class definitions commonly include the following elements:

1. Flows- Defining a routine for the nodes to run is an important task, and is usually used to update the ledger. Flows also contain a sub-class that is FlowLogic.

2. States- States help to define facts over which the agreement is reached, and they also implement the C0ntractState Interface.

3. Contracts- Contracts are an indispensable component of the CorDapp and they also define what constitutes a valid ledger update. Contracts implement the Contract interface in a CorDapp.

4. Services- Services provide the long-lived utilities in the node, and they have a Sub-class Singleton Serialization Token.

5. Serialization- Serialization whitelists and restricts the type of node that will receive off the wire, and implement the Serialization Whitelist interface.

Use Case

Before any code is started, it is important to understand the background and the requirement of the code. Here is one of the most common and popular use cases for this application. The example is the “IOU” process, wherein some-one requests to borrow some money.

Here is the sequence diagram of the IOU process:

As we can understand from the sequence, the borrower asks for some money, and if the lender agrees, then both of them remember the amount that is loaned. Overseeing the time and the way of this lending process, we focus simply on the intent of the borrowing and lending money.

Altering this sequence in Corda, we get a system in which determination of the amount that is to be borrowed becomes the creation of the transaction of this information. All the communication, the act of the borrowing is now replaced with the transaction in the process.

Finally, the following sequence is created:

1. States

Onto the coding sections, states have passed around the network between the nodes and eventually find themselves, stored on the ledger. In terms of the transaction, a state can be input or an output and many of them can also exist on a single transaction.

Below is the IOU State that will be passed around the application:

[Source: Corda]

2. Contracts

Contracts help you decide the valid input and output states for a command by all the parties involved in the transaction. Contracts are quite nice to write due to their expressiveness, and we can write conditions in the contracts that must be met for a transaction to be valid.

[Source: Corda]

3. Commands

The commands are used to verify the intention of the transaction, and they are put into connection to the contract as they determine what conditions can be validated. You can put these commands anywhere you want, such as in your file or outside of the contract class.

4. Flows

In Corda, flows are a central point where we can tie all the previous sections. States, contracts, and commands are written together to write a code that proposes a new transaction. These transactions are then sent to all the counterparties to sign and commit it to the ledger.

Below is the code as a whole:

[Source: Corda]

Building the transaction

Structure of the transaction

[Source: Corda]

  1. Transaction items

  • The output IOUState on the right represents the state that would be added to the ledger. In this example, there are no inputs, and therefore, we are not assuming any ledger states in the creation of IOU.

  • The Action command lists the IOU’s lender as a signer.

  1. Creating a transaction builder

To build the actual transaction, we need to add a TransactionBuilder, which is a mutable transaction class to which we can add inputs, outputs, commands, and other items of the transaction.

Once we have our TransactionBuilder, we add the following components:

  • The command is added using TransactionBuilder.addCommand.

  • The output is added using TransactionBuilder.addOutputState.

Signing and Finalizing the transaction

We sign the transaction using ServiceHub.signInitialTransaction, which returns a SignedTransaction. A SignedTransaction is an object that pairs a transaction with a list of signatures over that transaction.

Now, when we have a valid signed transaction, we just have to get to the notary to get it signed, and sent to relevant stakeholders.


Long story short, CorDapp is a distributed ledger technology that allows next-gen transparency, security and efficiency in your business. Only Corda allows you to build interoperable Blockchain network that transacts in pure privacy. The features included in the CorDapp are tremendous and fascinating.

Want to learn more about building awesome Blockchain application on Corda? Be sure to visit us at, or drop us a line at

Debut Infotech is an enterprise working on Mobile, web and Blockchain App development and have a global ecosystem of working across multiple industries.

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Debut Infotech A Top-Rated Web, Mobile, & Blockchain App Development Company

Debut Infotech is a global mobile app and digital product development company that leverages Blockchain, IoT, AI, and other cutting-edge technologies to help SMEs, startups, and global enterprises harness the incredible power of modern digital products to drive their online businesses to unwavering new heights. 

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