Blockchain CBSA Practice Test - Questions Answers, Page 12

The CA (Fabric CA by default) issues a root certificate (rootCert) to each member (organization or individual) that is authorized to join the 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

Chaincode is a decentralized transactional program, running on the validating nodes. As with every chaincode, it implements the Chaincode interface in particular, Init and Invoke functions. Init is called during Instantiate transaction after the chaincode container has been established for the first time, allowing the chaincode to initialize its internal data. Invoke is called to update or query the ledger in a proposal transaction. Updated state variables are not committed to the ledger until the transaction is committed.

hyperledger is an open source collaborative effort created to advance cross-industry blockchain technologies. It is a global collaboration, hosted by The Linux Foundation, including leaders in finance, banking, Internet of Things, supply chains, manufacturing and Technology.

The ledger system in Hyperledger fabric uses levelDB. By definition, LevelDB allows concurrent writers to safely insert data into the database by providing internal synchronization. LevelDB uses very coarse-grained synchronization which forces all writes to proceed in an ordered, first-come-first-served basis, effectively reduces throughput to a single thread. State database options include LevelDB and CouchDB. LevelDB is the default key-value state database embedded in the peer process. CouchDB is an optional alternative external state database. Like the LevelDB key-value store, CouchDB can store any binary data that is modeled in chaincode (CouchDB attachment functionality is used internally for nonJSON binary data). But as a JSON document store, CouchDB additionally enables rich query against the chaincode data, when chaincode values (e.g. assets) are modeled as JSON data.

Hyperledger Composer has following main components:

1) Business Network Archive: Capturing 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.

2) Composer Playground: 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. Theplayground 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

Endorsing Peers (Endorsers) 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.

Difficulty and Timestamp block also contains two very important parameters: a difficulty and a timestamp. The difficulty regulates how hard it is to find a block by the miner. The mining time is set to be between 10 and 20 seconds. If it's beyond 20 seconds, the difficulty is too high and will be automatically lowered going forward. If the mining happens below 10 seconds, then the difficulty increases. The timestamp is the time when a miner found the block. It is not automatically derived, rather it is set by the miner itself and can thus be influenced to a certain degree. The timestamp does not depend on the time zone, as it's the standard Unix timestamp.