In order to create an Todo List app that is backed by Blockchain on Mac OSX, you need to install certain prerequisites for Hyperledger Composer.
On any system, before proceeding any further, make sure that you have the following dependencies installed:
- OSX Only -- Install Xcode
- Docker version 17.03 or later
- Docker-compose version 1.11.2 or later
- Node.js version 8.9 or higher
- npm v5.x
- Python 2.7.x
- Hyperledger Composer version 0.16.0 or later
- Yeoman Generator version 2.0 or later
Once you have Docker and Docker-compose installed, you can download and and start Hyperledger Fabric v1.0.4 as shown below:
$ cd ~/Workdir
$ git clone https://github.com/sanjay-saxena/subrogation-network
$ cd ~/Workdir/subrogation-network
$ npm install
$ ./fabric-tools/downloadFabric.sh
$ ./fabric-tools/startFabric.sh
$ ./fabric-tools/createPeerAdminCard.sh
Hyperledger Composer provides higher-level abstractions to hide the complexity of the blockchain technologies that are implemented as part of Hyperledger Fabric. A Blockchain app that is built by Hyperledger Composer relies on a Business Network as an abstraction that helps orchestrate the transfer of assets. A Business Network comprises of Business Model, Business Logic, and Access Control Lists.
The following sections provide the steps for creating the Insurance Subrogation app backed by Blockchain. The Business Network is extremely simple and does not have support for authentication or authorization and so it will only contain the Business Model and Business Logic and there is no Access Control Lists defined in the network. The repo includes some scripts for creating a Business Network Archive(.bna), deploying the archive to Hyperledger Fabric, etc. for convenience.
Business Model consists of Participants, Assets, Transactions, and Events. It is expressed using a Domain Specific Language called Concerto. A very simple business model for Subrogation is defined in models/subrogation.cto.
Hyperledger Composer allows Business Logic to be implemented using Javascript and provides a rich set of APIs to update and query the world state.
The business logic for the Subrogation Business Network is implemented in lib/logic.js. For each of the transaction types that are defined in the model, there is a corresponding transaction processor function that implements the business logic for that transaction.
For example, when the Bootstrap transaction is submitted, Hyperledger Composer runtime will eventually invoke the following onBootstrap() function:
/**
* Bootstrap the world state for convenience.
* @param {org.example.subrogation.Bootstrap} txn -- Bootstrap transaction
* @transaction
*/
function onBootstrap(txn) {
....
var factory = getFactory();
// Insurance Agents
var mr_incredible = factory.newResource(ROOT_NAMESPACE,
'Agent',
'mr.incredible@example.com');
mr_incredible.firstName = "Bob";
mr_incredible.lastName = "Parr";
mr_incredible.password = "family-man-of-steel";
mr_incredible.title = "Principal Insurance Agent";
mr_incredible.company = 'ACME_CORP';
agents.push(mr_incredible);
....
// Policy Holders
var batman = factory.newResource(ROOT_NAMESPACE,
'PolicyHolder',
'batman@example.com');
batman.firstName = "Bruce";
batman.lastName = "Wayne";
batman.password = "holy blockchain, robin!"
batman.policies = [];
policyHolders.push(batman);
....
return getParticipantRegistry('org.example.subrogation.Agents')
.then(function(agentRegistry) {
return agentRegistry.addAll(agents);
})
.then(function() {
return getAssetRegistry('org.example.subrogation.Claim');
})
.then(function(claimRegistry) {
return claimRegistry.addAll(claims);
})
.catch(function (error) {
console.log(error);
throw error;
})
;
}
which implements the business logic for Bootstrap transaction. Similarly, the business logic for other transactions is implemented in their corresponding transaction-processor functions which eventually update the world state.
Once the Business Model and Business Logic is ready, they can be packaged up in a Business Network Archive(.bna) as shown below:
$ cd ~/Workdir/subrogation-network
$ ./scripts/createArchive.sh
This will result in the creation of subrogation-network@1.0.0.bna.
Assuming that Hyperleder Fabric is running, here is the step to deploy subrogation-network@1.0.0.bna to it:
$ cd ~/Workdir/subrogation-network
$ ./scripts/installPeerAdminCard.sh
$ ./scripts/startNetwork.sh
$ ./scripts/importNetworkAdminCard.sh
In order to populate the world state for convenience, the Bootstrap transaction can be submitted as shown below:
$ cd ~/Workdir/subrogation-network
$ ./scripts/bootstrapTransaction.sh
You can use ./scripts/list.sh to look at the assets that were created by the Bootstrap transaction.
First, install the generator as shown below:
$ npm install -g generator-hyperledger-composer
$ npm install -g yo
Here is the step to generate the Angular2 app for Subrogation using Yeoman:
$ cd ~/Workdir/subrogation-network
$ yo hyperledger-composer:angular
Welcome to the Hyperledger Composer Angular2 skeleton app generator
? Do you want to connect to a running Business Network? Yes
? What is the name of the application you wish to generate?: angular-app
? Description of the application: Skeleton Hyperledger Composer Angular project
? Author name: xxxx xxxxx
? Author email: foo@example.com
? License: Apache-2.0
? Name of the Business Network card: admin@subrogation-network
? Do you want to generate a new REST API or connect to an existing REST API? Generate a new REST API
? REST server port: 3000
? Should namespaces be used in the generated REST API? Never use namespaces
Created application!
Completed generation process
....
This will result in the generation of Subrogation app in the angular-app sub-folder.
You can run the app as shown below:
$ cd ~/Workdir/subrogation-network
$ cd angular-app
$ npm start
The app will be compiled and you can eventually interact with it by pointing your browser to http://localhost:4200. Also, you can look and play with the generated REST APIs or endpoints by
pointing your browser to the Loopback Explorer at http://localhost:3000/explorer. You can
also exercise the REST API to retrieve all the Tasks that were created by the
Bootstrap transaction by pointing your browser to http://localhost:3000/api/Task to
receive JSON response containing all the tasks in the world state.