Unit 4: Hyperledger Fabric

• Hyperledger is an enterprise-grade, open-source distributed ledger framework launched by the Linux Foundation in December 2016.
• Fabric is a highly-modular, decentralized ledger technology (DLT) platform that was designed by IBM for industrial enterprise use.
• Because Hyperledger Fabric is private and requires permission to access, businesses can segregate information (like prices), plus transactions can be speed up because the number of nodes on the network is reduced.Fabric 2.0 was released in January 2020. The main features of this version are faster transactions, updated smart contract technology, and streamlined data sharing.

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• The Linux Foundation (the same corporation behind the Linux Operating System) launched the Hyperledger blockchain initiative in December 2015. This project was established as a core for both the collaborative production of fully accessible blockchain technology and distributed ledgers.

The Architecture of Hyperledger Fabric System-�

• The design of the Hyperledger Fabric System.
• Assets-
• Assets can vary from the physical (property investment and equipment) to the immaterial (software and trade secrets). By using the chain code transaction process, Hyperledger Fabric allows users to alter assets. 
• In the Hyperledger Fabric system, assets are portrayed as a series of key-value pairs, with state changes registered as exchanges on a ledger path. Binary and JSON representations are available for assets.
• Chaincode-
• Chaincode is the commercial concept software that defines one or multiple assets and the transaction methods for managing the purchase (s). The criteria for accessing or changing key-value pairs or any other dynamic database entries are enforced by Chaincode. Chaincode operations are started with a transaction idea and run against the ledger’s existing state information. The implementation of Chaincode generates a collection of key-value writes that can be sent to the system and implemented to the ledgers of all users.
• Ledger-
• All value changes in the fabric are recorded in a sequential, damage-resistant ledger. Chaincode abstractions (‘transactions’) supplied by interacting parties cause state shifts. Every transaction generates a collection of asset key-value pairs that have been created, updated, or deleted in the ledger. 
• A blockchain is used to store permanent, sequential records in blocks, and a database file is used to keep track of the present fabric state. Each channel has only one ledger, which performs an error handling check is conducted before adding a block to guarantee that the conditions of assets that were fetched have not altered since chain code processing time.

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• Security- 
• Hyperledger Fabric is the foundation of a transactional system in which all members are acknowledged. Cryptographic licenses are related to businesses, networking equipment, and application developers or client apps via Public Key Infrastructure. As an outcome, data access management on the system and channel stages can be regulated and managed. In this way, it makes it secure. 
• Consensus-
• Consensus has gradually been associated with a specific method within a particular target in distributed ledger architecture.  On the other hand, consensus entails more than just responding on transaction execution, and this distinction is underscored in Hyperledger Fabric by its central position in the whole transaction pipeline, from request and approval to ordering, verification, and pledge. In a word, the consensus is the total authentication of the accuracy of a group of transactions that make up a block.
• Confidentiality-
• Hyperledger Fabric uses an unchangeable ledger and a chain code that may edit and alter the present state of objects. A ledger can operate within the range of a channel — it could be broadcast throughout the existing system or privately run to include precisely a limited number of users. 

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How Hyperledger Fabric Works

• Traditional blockchain networks can’t support private transactions and confidential contracts that are of utmost importance for businesses. Hyperledger Fabric was designed in response to this as a modular, scalable and secure foundation for offering industrial blockchain solutions.
• Hyperledger Fabric is the open-source engine for blockchain and takes care of the most important features for evaluating and using blockchain for business use cases.
• Hyperledger Fabric supports memberships based on permission; all network participants must have known identities. Many business sectors, such as healthcare and finance, are bound by data protection regulations that mandate maintaining data about the various participants and their respective access to various data points. Fabric supports such permission-based membership

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Modular Architecture

• The modular architecture of Hyperledger Fabric separates the transaction processing workflow into three different stages: smart contracts called chaincode that comprise the distributed logic processing and agreement of the system, transaction ordering, and transaction validation and commitment. This segregation offers multiple benefits:
• A reduced number of trust levels and verification that keeps the network and processing clutter-free
• Improved network scalability
• Better overall performance
• Additionally, Hyperledger Fabric’s support for plug-and-play of various components allows for easy reuse of existing features and ready-made integration of various modules. For instance, if a function already exists that verifies the participant’s identity, an enterprise-level network simply needs to plug and reuse this existing module instead of building the same function from scratch.
• The participants on the network have three distinct roles:
• Endorser
• Committer
• Consenter

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Since only confirming instructions—such as signatures and read/write set—are sent across the network, the scalability and performance of the network is enhanced. Only endorsers and committers have access to the transaction, and security is improved with a fewer number of participants having access to key data points.

Example of Hyperledger Fabric

• Suppose there's a manufacturer that wants to ship chocolates to a specific retailer or market of retailers (i.e., all US retailers) at a specific price but does not want to reveal that price in other markets (i.e., Chinese retailers).
• Since the movement of the product may involve other parties, like customs, a shipping company, and a financing bank, the private price may be revealed to all involved parties if a basic version of blockchain technology is used to support this transaction.
• Hyperledger Fabric addresses this issue by keeping private transactions private on the network; only participants who need to know are aware of the necessary details. Data partitioning on the blockchain allows specific data points to be accessible only to the parties who need to know.

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Hyperledger Composer

• Hyperledger Composer is an extensive, open development toolset and framework to make developing blockchain applications easier. Our primary goal is to accelerate time to value, and make it easier to integrate your blockchain applications with the existing business systems. You can use Composer to rapidly develop use cases and deploy a blockchain solution in weeks rather than months. Composer allows you to model your business network and integrate existing systems and data with your blockchain applications.
• Hyperledger Composer supports the existing Hyperledger Fabric blockchain infrastructure and runtime, which supports pluggable blockchain consensus protocols to ensure that transactions are validated according to policy by the designated business network participants.

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How does Hyperledger Composer work in practice?

• For an example of a business network in action; a realtor can quickly model their business network as such:
• Assets: houses and listings
• Participants: buyers and homeowners
• Transactions: buying or selling houses, and creating and closing listings
• Participants can have their access to transactions restricted based on their role as either a buyer, seller, or realtor. The realtor can then create an application to present buyers and sellers with a simple user interface for viewing open listings and making offers. This business network could also be integrated with existing inventory system, adding new houses as assets and removing sold properties. Relevant other parties can be registered as participants, for example a land registry might interact with a buyer to transfer ownership of the land.

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