Update Aug 29th 2019: Hyperledger Composer has been deprecated. Please see the README for more information.

Integrating Existing Systems

Integrating existing systems

Hyperledger Composer can be integrated with existing systems by using a Loopback API. Integrating existing systems allows you to pull data from existing business systems and convert it to assets or participants in a Composer business network.

Generating a REST API

Hyperledger Composer includes a standalone Node.js process that exposes a business network as a REST API. The LoopBack framework is used to generate an Open API, described by a Swagger document.

Publishing events from the REST server

The REST server can be configured to subscribe to events emitted from a deployed business network, and publish those events to client applications.

Enabling authentication for the REST server

The REST server can be configured to authenticate clients. When this option is enabled, clients must authenticate to the REST server before they are permitted to call the REST API.

Enabling multiple user mode for the REST server

The REST server can be configured to multiple user mode. Multiple user mode permits clients of the REST server to provide their own Blockchain identities for digitally signing transactions. This enables the business network to differentiate between different clients of the REST server.

Securing the REST server using HTTPS and TLS

When deploying Hyperledger Composer REST server in a production environment, the REST server should be configured to be secured with HTTPS and TLS (Transport Layer Security). Once the REST server has been configured with HTTPS and TLS, all data transferred between the REST server and all of the REST clients is encrypted.

Deploying the REST server for a business network

By deploying a REST server for a business network, you can integrate existing systems and data with your Hyperledger Composer business network, allowing you to create, update, or delete assets and participants, as well as get and submit transactions.

Customizing the REST server for a business network

By customizing a REST server for a business network, you can add your own code to implement new custom REST APIs for your business applications or additional authentication mechanisms that are not supported by the standard REST server,

Integrating with Node-RED

Node-RED includes a number of Hyperledger Composer nodes allowing you to submit transactions, read, update and delete assets and participants, and subscribe to events.

Calling external HTTP or REST services

Transaction processor functions can be used to call external REST services. This allows you to move complex computation off the blockchain.

For instructions on setting up a Loopback API, see Generating a REST API.