The global Call for Code is well underway, we want to share some visual recognition models which could help you. These AI models can operate on the edge, which could be particularly useful for this years’ theme: disaster preparedness. How could visual recognition help in relief work? From satellite and drone imagery analysis, to classifying...
Congrats! You’ve made it to the third in a series of code patterns that show you how to get started creating a blockchain application. In this pattern, you’ll learn how to emit events from the blockchain network so that external applications can subscribe to them and take action. As you’ve seen, blockchain’s trusted and immutable shared ledger is the foundation for innovative business solutions. Applications and external systems often need to know when something happens to the shared ledger. This pattern will show you how to programmatically generate and receive those notifications from the blockchain network.
Updated to support Hyperledger Fabric V1.1 and Hyperledger Composer V0.19
Imagine that you’ve listed a car for sale in the product auction network and you’re dreading the effort of tracking the auction process for the car. Hyperledger Composer provides a novel approach to automate the manual task of tracking the auction process by emitting event notifications. Transactions within Composer can be written to emulate CRUD operations on your assets to emit events when required. In the car auction case, you could listen to the “OfferEvent” event to get notified about the offers for the car, and have a printer listen to the “PrintBillOfSale” event to print details of the sale.
This pattern is an extension of the pattern to create a smart contract among a set of participants in a product auction network. In this pattern, you’ll learn how to emit events from a blockchain network and subscribe to them from external web applications.
- Start the Hyperledger Fabric network
- Generate and deploy the Business Network Archive
- Start and connect the Hyperledger Composer rest server to the deployed business network, and start the web application
Find the detailed steps for this pattern in the README. Those steps will show you how to:
- Generate the Business Network Archive (BNA).
- Deploy the Business Network Archive on Hyperledger Composer running locally.
- Start the web UI.
- Perform the transactions, and emit and handle events.
To complete this pattern, you should be familiar with the previous pattern to create a smart contract among a set of participants in a product auction network.