middleware

Middleware to Expose Trade Channel and Chaincode Capabilities (based on Fabric SDK Node)

To run the trade chaincode on the network created in network, we need to perform a sequence of bootstrapping and configuration operations. Any application that wraps the trade smart contract must have the capabilities to run those operations through an API. Hyperledger Fabric provides an SDK with library functions and an API for all the various primitives necessary to operate a channel and exercise a chaincode on that channel.

The middleware code consists of various wrapper functions that harness the Fabric SDK primitives (in the Node JS language) to run operations specific to our trade network and chaincode, and expose a high-level API that can be used by a standard web application.

Network Bootstrapping and Transaction Pipeline

The sequence of operations that need to be performed are as follows:

• Create a trade channel (or blockchain instance)
• Join peers of all the organizations to this channel
• Install the chaincode on every peer joined to the channel
• Instantiate the chaincode on this channel
• Expose Node JS API to invoke and query the trade chaincode

Pre-requisites to Exercise the Middleware and Run the Test Scripts

• Install node and npm on your system if you don't have them.
  • This code was developed and run with node version 9.8.0 and npm version 5.7.1 respectively.
  • Note: Older and newer versions may also work, but they are not guaranteed to do so.
• Run npm install to install the dependencies.

Configuring the Middleware

• The config.json file contains a specification of the network that will be used to host the trade channel and chaincode.
  • Make sure the parameters (hostnames, ports, etc.) match those in the network folder.
• The constants.js file contains various parameters that dictate how the application will behave, such as the endorsement policy.
  • Make sure that the chaincode paths are accurate (they should be relative to the folder ../chaincode/src/.)
  • Make sure that the channel ID (tradechannel) matches that used to create channel artifacts in the network folder.

Test Run to Create a Trade Instance Using the Smart Contract

Run node createTradeApp.js.
This script runs through the stages from channel creation through to chaincode instantiation.
It then runs a chaincode invocation to create a trade request on behalf of the importer, and then queries the chaincode for the trade status.

Test Run to Complete a Trade Contract Lifecycle after Setup

Run node runTradeScenarioApp.js.
This assumes that the createTradeApp.js script has run successfully.
It continues the trade smart contract lifecycle through to completion, as described in the use case document.
The parameters supplied in the various chaincode invocations match those in the chaincode unit tests.
Note: This script assumes that the initial version of the chaincode is currently deployed on the channel.

Test Run to Add a New Organization to the Network

• The config_upgrade.json contains the specification of the peer in the new organization (exportingentityorg.) Make sure the parameters (hostnames, ports etc.) match those in the network folder.
• Run node run-upgrade-channel.js to update the channel configuration: a new configuration block will be added to the channel blockchain.
  • Note: This script assumes that the crytographic and channel artifacts for the new organization have already been created.
• Run node new-org-join-channel.js to join the peer of the new organization to the tradechannel channel.
  • Note: This script assumes that the new organization's peer and CA have already been launched in docker containers.

Test Run to Upgrade the Chaicode

• Run node upgrade-chaincode.js to install the new version of the chaincode on all 5 peers, and upgrade the chaincode version on the tradechannel channel.
  • The chaincode transaction endorsement policy will also change from Constants.ALL_FOUR_ORG_MEMBERS to Constants.ALL_FIVE_ORG_MEMBERS.
  • Note: This script assumes that the new organization's peer and CA have already been launched in docker containers.
• Run node five-org-trade-scenario.js to run and observe the results of chaincode invocations and queries.
  • Note: This script assumes that the upgraded version of the chaincode is currently deployed on the channel.