CBDH Questions and Answers

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.

Kafka essentially is a distributed, horizontally-scalable, fault-tolerant, commit log. The other answers are in correct.

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The security module works in conjunction with the membership service module to provide access control service to any data recorded and business logic deployed on a chain network.

Peer nodes commits Transaction & keeps the data in sync across the ledger. They are nodes that maintain the state and copy of a shared ledger. Peers are authenticated by certificates issued by MSP. In Hyperledger Fabric, there are three types of peer nodes depending upon the assigned roles.

Distributed Ledger manages the world state and the transaction log in the blockchain. The world state is defined as the state of all transactions on the Blockchain, where all nodes agree that all blocks on the Blockchain are at the same state. It implements three key attributes. It efficiently calculates the cryptographic hash of the entire dataset of each block. It efficiently transmits a minimal “delta” changes to the dataset, when a peer is out of sync and needs to “catch up”. It minimizes the amount of stored data required for each peer to operate.

Hyperledger is a private validator network protocol. All the entities in a network must register with membership services to obtain an identity with access and transaction authority on the network. Validators determine the level of permissions required to transact. The network setup also defines the network as permissive, allowing the ease of access. It supports for rapid and high adoption for a more controlled and restrictive environment.

Hyperledger makes use of the permissioned voting-based consensus from the pool of other consensus named the lottery-based consensus. (Kafka in Hyperledger Fabric Ordering Service) Voting-based algorithms are advantageous in that they provide low-latency finality. More Nodes = More Time to reach Consensus. Trade off between Scalability and Performance

Assembler languages are not web or html friendly nor high level.

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.

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Code invoking transaction is an REST API call to a chaincode function and is similar to how a URL pattern invokes a servlet in J2EE. ServletServlet can be used to create a default mappings for servlets. For example, to create a default mapping to map all servlets to /myservlet/*, so the servlets can be called using http://host:port/web-app-name/myservlet/com/foo/FooServlet, add the following to your web.xml file. (The web.xml file is located in the WEB-INF directory of your Web application.) ServletServlet weblogic.servlet.ServletServlet ServletServlet /myservlet/*

Hyperledger Cello is a blockchain provision and operation system, which helps manage blockchain networks in an efficient way. Cello is a tool that could be used for example by vendors and VARs to provide a BaaS to their customer base.

Peers are connected to the channel and can receive all the transactions that are broadcasted on that channel. Consensus takes place within a channel by members of the channel only. Channels are membership based.

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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.

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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