Hyperleger Composer Architecure Deep Dive

Hyperledger ComposerArchitecture Deep Dive

Dan Selman

2017-07-25 (v0.10.0)

A day in the life of a Composer transaction…

ComposerClient

FabricClient

Composer Chaincode

(Go)

Composer Runtime (JS)

End-UserUserCode(JS)

FabricShim(Go)

Duktape JS VM

Peer

ComposerREST

Server

Events

Business Network Definition(Programming Model)

Connect and Deploy

• Load the BusinessNetworkDefinition• BusinessNetworkDefinition.fromArchive or fromDirectory

• Deploy a business network• AdminConnection.connect(connectionProfileName)

• Connection profiles are loaded from disk. They are JSON documents that include all the information required to connect to a channel on a Fabric (or other runtimes)

• AdminConnection.deploy(businessNetworkDefinition, options)• Options can include the endorsement policy• Deployment is currently an install followed by an instantiate. We are breaking these

steps apart.• Install Composer chaincode (Go), instantiate Composer chaincode (Go), send a HLF

transaction with the business network archive payload to the chaincode.• BusinessNetworkDefinition archive is stored in the world-state on the blockchain

Submit Transaction

• Create a BusinessNetworkClient connection• BusinessNetworkClient.connect(connectionProfileName)

• BusinessNetworkClient.submitTransaction(tx)• TX is validated against the model

• TX is serialized to JSON

• Use Node-SDK to submit the JSON payload to the Composer system chaincode

Handle Transaction (on peer)

• Validate the JSON for the transaction against the model

• Attempt to resolve the relationships in the transaction

• Call the Access Control Engine to determine whether the current participant has permission to execute this transaction

• Find all Transaction Processor functions that are subscribed to the type of the transaction

• For each:• Invoke the function

• All access to assets, participants and transactions are filtered through the declarative Access Control Engine

Composer “Current Participant”

• Fabric access is authenticated using the standard certificate based authentication mechanism

• Composer system chaincode maps the fingerprint for certificate used to submit the transaction to a Composer participant. A Participant is a modelled entity in a business network, which could represent a user/org/system, with arbitrarily complex metadata and relationships

• Composer includes APIs and CLIs to manage the mapping from a certificate to a Participant instance.• Issue identity, revoke, bind

• A single participant could have multiple identities (certificates)

Composer REST Server

• Based on Open Source LoopBack technology• Connect to a Business Network• Introspect the model (assets, participants, transaction, queries)• System types: identities, ping etc

• Automatically generate strongly-typed REST routes based on the model for the business network definition

• Uses the Open Source passport.js framework for authentication• Supports 100+ authentication provides, Twitter, GitHub, LDAP, OAuth,IBM ID etc.

• Wallet REST APIs map from an external ID (e.g. GitHub) to a PKI certificate

• Wallet persistence is delegated to LoopBack (so supports 20+ relational and non-relational back-ends