How to make App with Hyperledger fabric and composer

HyperLedger Fabric + Composer
- How to make Blockchain App -
KUNITO Atsunori

HyperLedger FabricHyperLedger Composer Playground
Client API REST Server
Other Lang
Application
Node.js
Application
Composer CLI
Business Network Archive
Model
Query
Transaction
Acl
Card
Phase.1
Develop & Test BNA
Phase.2
Deploy BNA
Phase.3
Develop Your App
export

What is BNA?
• BNA = Business Network Archive
• Literally , It’s a Archive file. It involve files
described below.
Purpose Similar part of Traditional DB
Model Define assets Create table statement(DDL)
Query Define Query with subset of assets,
sort order, and condition.
View or Select statement.
Transaction Chaincode.(a.k.a smart contract)
Update Assets and execute check or
related process.
Stored Procedure
ACL Access control Grant

Work with Playground.
• https://composer-
playground.mybluemix.net/login
• Develop your BNA.
• Test your BNA.
– Create asset , submit transaction.
– Those action are virtual. It works with browser’s local
storage.
– [TIPS] console.log() is available in transaction. It
outputs to browser console.
• If you done testing, export BNA.

Sample of Model.
/**
* A Task
*/
asset Task identified by taskId {
o String taskId
o String title
o String envId
o DateTime start
o DateTime end
o TaskStatus status
o String commander
o String approver
}
enum TaskStatus {
o REGISTERED
o STARTED
o FINISHED
}
It’s very similar to DDL.
You can define enumration.

Sample of Query.
query getTaskByStatus{
description: "Select all tasks with supplied status parameter"
statement:
SELECT xxxx.cossh.model.Task
WHERE (status == _$statusParam)
ORDER BY [start ASC]
}
It’s very similar to SQL.
Query Parameter.

Sample of Transaction.
function startTask(tx) {
console.log('startTask[' + tx.task + "]");
var targetTask = {};
// get task
return getAssetRegistry(‘xxxx.cossh.model.Task')
.then(function (registry) {
var ret = registry.get(tx.task.taskId);
return ret;
}).then(function (task) {
targetTask = task;
targetTask.status = 'STARTED';
return getAssetRegistry(‘xxxx.cossh.model.Task');
}).then(function (registry) {
return registry.update(targetTask);
}).catch(function(e){
console.log('not found?:' + e);
});
}
You can implement checks ,
Related process.
Update asset.
This function can be called in Transaction only.

Sample of ACL.
permissions.aclrule NetworkAdminUser {
description: "Grant business network administrators full access to user resources"
participant: "org.hyperledger.composer.system.NetworkAdmin"
operation: ALL
resource: "**"
action: ALLOW
}
rule NetworkAdminSystem {
description: "Grant business network administrators full access to system
resources"
participant: "org.hyperledger.composer.system.NetworkAdmin"
operation: ALL
resource: "org.hyperledger.composer.system.**"
action: ALLOW
}
It grants all permissions to NetworkAdmin.
It’s pretty enough while developing.

Deploy BNA.
• Create admin card.
– Card is a another archive file. It contains …
– If you used fabric-dev-server , simply run createPeerAdminCard.sh.
• Install & Start BNA.
– [TIPS] network start command create new card file. Application will connect to Fabric with this new
card. So import new card in this step.
Connection.json Fabric Information that connect to.
certificate Public key.
privateKey Secret key.
composer network install -a cossh-network.bna -c PeerAdmin@hlfv1
composer network start --card PeerAdmin@hlfv1 -n cossh-network -V 0.0.2-deploy.6 --networkAdmin
admin --networkAdminEnrollSecret ******* --file networkadmin.card -l INFO
composer card import --file networkadmin.card

Connect to Fabric from App.
• Option 1. Client API.
– API for Node.js
– If Your App were Node.js , This is a straight forward approach.
– [TIPS] When Your App start up , load card which created by network
start command. You can use AdminConnection.importCard() for this.
– [TIPS] API version is very sensitive because Composer improve day by
day. Then You should carefully choose package version. Basically ,
Client API , Composer CLI , Playground should have same version
number.
• Option 2. Composer REST Server.
– REST Server is a package for Node.js.
– It’s generate REST API for creating assets , submitting transaction ,
running queries.
– It expose those REST API on http://localhost:3000.

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