CBDH BTA Certified Blockchain Developer – Hyperledger Questions and Answers

Gossip Protocol The gossip data dissemination protocol performs three functions Manages peer discovery and channel membership Disseminates ledger data across all peers on the channel Syncs ledger state across all peers on the channel.

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Chaincode Interface is required and supports Go, Node.js or Java.

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The Infrastructure Module includes the following four modules: Technical, Legal, Marketing, and Organizational.

Rootcert, tcert and ecert. As The CA (Fabric CA by default) issues a root certificate (rootCert) to each member (organization or individual) that is authorized to join the network. The CA also issues an enrollment certificate (eCert) to each member component, server-side applications and occasionally end users. Each enrolled user is granted an allocation of transaction certificates (tCerts). Each tCert authorizes one network transaction.

There are two parts: 1. Business Network Archive which essentially captures the core data in a business network, including the business model, transaction logic, and access controls, the Business Network Archive packages these elements up and deploys them to a runtime. Business Network Archive files are stored as “.bna” files. AND 2. Composer Playground which is web-based tool allows developers to learn Hyperledger Composer, model out their business network (domain), test that network, and deploy that network to a live instance of a blockchain network. The playground keeps the development model in browser storage, allowing them to be easily uploaded or downloaded.

Hyperledger business blockchain frameworks reach consensus by performing two separate activities: 1. Ordering of transactions 2. Validating transactions by logically separating these activities, we ensure that any Hyperledger framework can work with any Hyperledger consensus module.

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This web-based tool allows developers to learn Hyperledger Composer, model out their business network (domain), test that network, and deploy that network to a live instance of a blockchain network. The playground keeps the development model in browser storage, allowing them to be easily uploaded or downloaded. The playground also allows for CRUD (create, read, update, delete) operations to be performed on asset transactions which are created and logged. Composer playground offers a repository of sample business networks that can provide a base for building your own business network.

There is a new open-source application development framework, which simplifies the creation of Hyperledger Fabric blockchain applications, thus reducing the time and complexity of development. The tool aims at helping users to create blockchain applications based on Hyperledger Fabric without needing to know the low-level (Go Programming) details involved in blockchain networks.

State Based y default, endorsement policies are specified for a channel’s chaincode at instantiation or upgrade time (that is, one endorsement policy covers all of the state associated with a chaincode). However, there are cases where it may be necessary for a particular state (a particular key-value pair, in other words) to have a different endorsement policy. This state-based endorsement allows the default chaincode-level endorsement policies to be overridden by a different policy for the specified keys.

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Hyperledger Fabric is an enterprise permissioned blockchain. It does not have a cryptocurrency nor token. It could be a use case to develop chaincode to create an off chain channel to a cryptocurrency exchange but this would not be efficient.

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Chaincode may be deployed on multiple channels, each instance is isolated within its channel. Each channel maintains their own chaincode and ledger.

Cryptography is used in Blockchain to address the issues and concerns of privacy. Cryptography is the study of how to send information back and forth securely in the presence of adversaries. A cryptographic function is a function for encoding or encrypting data to protect the contents from others. The following components are the basis of a cryptographic function: The Secret: The data which we are trying to protect The Key: A piece of data used for encrypting and decrypting the secret The Function: The process or function used to encrypt the secret The Cipher: The encrypted secret data, output of the function The Secret and the Key are passed into the Function to create a Cipher.

This web-based tool allows developers to learn Hyperledger Composer, model out their business network (domain), test that network, and deploy that network to a live instance of a blockchain network. The playground keeps the development model in browser storage, allowing them to be easily uploaded or downloaded. The playground also allows for CRUD (create, read, update, delete) operations to be performed on asset transactions which are created and logged. Composer playground offers a repository of sample business networks that can provide a base for building your own business network.

Docker provides a secured, lightweight method to sandbox chaincode execution that is " locked down " Chaincode Services uses Docker to host (deploy) the chaincode without relying on any virtual machine or computer language. Docker provides a secured, lightweight method to sandbox chaincode execution. The environment is a " locked down " and secured container, along with a set of signed base images containing secure OS and chaincode language, runtime and SDK images for Golang Additional programming languages can be enabled

A tokenless ledger refers to a distributed ledger that doesn’t require a native currency to operate. Generally, in a private blockchain tokens are not needed due to resources controlled by one party.

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REST (Representational State Transfer) Server is often used to proxy requests to Hyperledger chaincode. This provides a well-defined process for accessing blockchain services.

Proposal is A transaction request sent from a client or admin user to one or more peers in a network; examples include deploy, invoke, query, or configuration request.

https://fabrictestdocs.readthedocs.io/en/latest/glossary.html

To create a network according to an organization ' s structure, and to bootstrap a channel, we will need to generate the following artifacts: A genesis block, containing organization-specific certificates that serve to initialize the Fabric blockchain. Channel configuration information. Anchor peer configurations for each organization. An anchor peer serves as a fulcrum within an organization, for cross-organization ledger syncing using the Fabric gossip protocol.

It has a modular subsystem design so that different implementations can be plugged in and implemented over time. Modular and extensible means modularity in all components of all frameworks, including: Consensus layer Smart contract layer Communication Layer Data Store Identity services (root of trust, to identify the participants).

Blockchain services manages the distributed ledger through a peer to peer protocol that is built on HTTP/2. The optimized data structure provides efficient schemes for maintaining the world state (the state of all transactions on the Blockchain) replicated at many participants.

bna is also know as a " banana " file in the hyperledger world. Before a business network definition can be deployed it must be packaged into a Business Network Archive (.bna) file. The composer archive create command is used to create a business network archive file from a business network definition folder on disk.

REST API support and integration capabilities: A LoopBack connector for business networks has been developed that exposes a running network as a REST API which can easily be consumed by client applications and integrate non-blockchain applications. This allows for easier front end application development without having to know the network internal application structure.

A REST (Representational State Transfer) Server is often used to proxy requests to Hyperledger chaincode. This provides a well defined process for accessing blockchain services.

Chaincode has an endorsement policy which specifies the set of peers on a channel that must execute chaincode and endorse the execution results in order for the transaction to be considered valid.

Chaincode Services uses Docker to host (deploy) the chaincode without relying on any virtual machine or computer language. Docker provides a secured, lightweight method to sandbox chaincode execution. The environment is a " locked down " and secured container, along with a set of signed base images containing secure OS and chaincode language, runtime and SDK images for Golang. Additional programming languages can be enabled, if required.

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Hyperledger Composer is an open-source application development framework which simplifies the creation of Hyperledger Fabric blockchain applications, thus reducing the time and complexity of development. The tool aims at helping users to create blockchain applications based on Hyperledger Fabric without needing to know the low-level (Go Programming) details involved in blockchain networks.

Hyperledger explorer: Hyperledger explorer, which was originally contributed by IBM, Intel, and DTCC, can view, invoke, deploy or query blocks, transactions and associated data, network information (name, status, list of nodes), chain codes and transaction families, as well as other relevant information stored in the ledger.

Endorsing Peer Endorser peer Peers can be marked as Endorser peer (i.e. Endorsing peer). Upon receiving the “transaction invocation request” from the Client application the Endorser peer Validates the transaction. Check certificate details and roles of the requester. Executes the Chaincode (Smart Contract) and simulates the outcome of the transaction. But it does not update the ledger. At the end of the above two tasks the Endorser may approve to disapprove the transaction. As only the Endorser node executes the Chaincode (Smart Contract) so there is no necessity to install Chaincode in each and every node of the network which increases the scalability of the network.

An endorser executes and endorses transactions. The endorsing peers take the role of endorsing transactions before they are ordered and committed as per the policy defined in Chaincode.

Kafka is the Hyperledger Fabric ordering mechanism that is recommended for production use. This ordering mechanism utilizes Apache Kafka, an open source stream processing platform that provides a unified, high-throughput, low-latency platform for handling real-time data feeds.