As we introduced briefly in the previous chapter, Hyperledger Composer is built on top of the Hyperledger Fabric blockchain. It provides a set of tools to help developers rapidly develop use cases and deploy a blockchain solution quickly. Hyperledger Composer is built with JavaScript, leveraging modern tools including Node.js and NPM. It involves a business-centric, driven development process and helps developers to digitize and model business networks.

Hyperledger Composer is a toolbox of helpful tools that includes the following:

• A modeling language called CTO
• Composer Playground, which is a web interface for the rapid building and testing of a business network
• Command-line interface (CLI) tools for integrating modeled business networks (created using Hyperledger Composer) in a running instance of the Hyperledger Fabric network

We introduced the Composer Playground in the previous chapter. In this chapter, we will discover the CTO and CLI tools.