Summary
In my previous blog post on the blockchain, I briefly introduced the architecture of the blockchain, link: Blockchain Learning - Blockchain Architecture . So in this article, I will continue to briefly introduce the classification of blockchain.
According to the network range
According to the network scope, blockchain can be divided into public chain, private chain, and alliance chain.
1. Public chain
The so-called public ownership means that it is completely open to the outside world, and anyone can use it at will, with no restrictions on permissions and no identity authentication. Bitcoin is a public chain network system. When you use the Bitcoin system, you only need to download the corresponding software client, create wallet addresses, transfer transactions, and mine operations. These functions can be used freely. Since the public chain system has no third-party management at all, it relies on a set of predetermined rules to ensure that each participant can initiate reliable transactions in an untrusted network. Generally speaking, any system that requires public participation and the maximum guarantee of openness and transparency of data is suitable for public chains, such as digital currency systems, crowdfunding systems, financial transaction systems, etc.
It should be noted here that in the environment of the public chain, the number of nodes is not fixed, the online or not of the nodes is also uncontrollable, and even some nodes may be malicious nodes. When I introduced the blockchain workflow, I mentioned a question. In this case, how do you know that the data is confirmed by the majority of nodes? In fact, in the public chain environment, this problem has not been solved very well. At present, the most appropriate method is to continuously synchronize with each other. Finally, the chain formed by the consistent block data of most nodes in the network is recognized. main chain, which is also known as eventual consistency.
2. Private chain
The private chain is a concept opposite to the public chain. The so-called private refers to the system that is not open to the outside world and is only used within the organization, such as enterprise bill management, financial auditing, supply chain management, etc., or some government management systems. In the process of using the private chain, there are usually registration requirements, that is, identity authentication needs to be submitted, and there is a set of rights management system. Some friends may ask, although Bitcoin, Ethereum and other systems are public chain systems, if these systems are built in a local area network that is not connected to the external network, won’t this become a private chain? From the perspective of network propagation, it can be calculated, but because the system used does not have any identity authentication and permission settings, from a technical point of view, this situation can only be regarded as a private system built by clients using the public chain system. Test the network. Of course it also applies to enterprise applications.
In the private chain environment, the number of nodes and the status of the nodes are usually controllable. Therefore, in the private chain environment, it is generally not necessary to screen the packagers of block data through competition. PoS (Proof of Authority), DPoS (Delegated Proof of Stake), PBFT (using Byzantine Fault Tolerance Algorithm), etc. mentioned in the introduction of the above consensus mechanism.
3. Alliance Chain
The network-wide balance of the alliance chain between the public chain and the private chain is usually used in the environment of multiple member roles, such as payment settlement between banks, logistics between enterprises, etc. In these scenarios, different permissions are often used. Like the private chain, the alliance chain system generally has identity authentication and permission settings, and the number of nodes is often determined, which is suitable for transaction processing between enterprises or institutions. The alliance chain does not have to be fully controlled. For example, in the financial system, some data can be partially released from the external labor card.
Since consortium chains are generally used between definite institutions, like private chains, the number and status of nodes are also controllable, and a more energy-efficient and environmentally friendly consensus mechanism is usually used.
According to the deployment environment
1. Main chain
The so-called main chain is the real blockchain system deployed in the production environment. The software will go through a lot of internal test versions before the official release to find some possible bugs and use it for internal demonstrations to view the results. , and finally the official version will be officially released. The main chain can also be said to be the blockchain network composed of the official version of the client. Only the main chain will be really popularized and used, and the design of each function is relatively complete. In addition, sometimes, the blockchain system will be forked due to various reasons, such as small forks temporarily generated during mining, etc., so the longest original chain becomes the main chain
2. Test chain
This is also very understandable, that is, developers can learn to use the blockchain systems provided for testing purposes, such as the Bitcoin test chain, the Ethereum test chain, etc. Of course, it is not that the tree has to be a blockchain developer. A test chain is provided, and users can also build a test network by themselves. There can be some differences between the functional design in the test chain and the main chain in the production environment. For example, the main chain uses the proof-of-work algorithm for mining, and the test chain can be replaced with other algorithms for testing.
According to docking type
1. Single chain
A blockchain system that can run alone can be a "single chain", such as the Bitcoin main chain, the test chain, the Ethereum main chain and the test chain; the consortium chain built by Fabric in the Hyperledger, etc. These blockchain systems have A perfect component module, a system of its own. Everyone should pay attention that for some software systems, such as the crowdfunding system or financial guarantee system based on Ethereum, this writing can only be regarded as a smart contract application, not an independent blockchain system. The operation of the application requires an independent The support of the blockchain system.
2. Sidechain
Sidechain is a cross-chain technology of blockchain system. This concept is mainly initiated by Bitcoin sidechain. With the development of technology, in addition to Bitcoin, more and more blockchain systems have emerged. Each system has its own advantages and characteristics. How to combine different chains to open up information islands and complement each other? Sidechains are one such technology.
In the case of Bitcoin, the Bitcoin system is mainly designed to implement digital encryption, and the business logic has been solidified. Therefore, it is not suitable for other functions, such as financial contracts, small-value fast payments, etc. However, Bitcoin is currently the largest public blockchain system with advantages in reliability, decentralization, etc. So how to use the advantages of the Bitcoin network to run other blockchain systems? Consider building a new blockchain system on top of the existing Bitcoin blockchain. The new system can have many functions that Bitcoin does not have, such as private transactions, fast payment, etc., and can be compatible with Bitcoin the main chain to communicate with each other. Simply put, a sidechain is a new type of blockchain that anchors Bitcoin. The sidechains anchored to Bitcoin currently include ConsenSys' BTCRelay, Rootstock and BlockStream's element chains.
The blockchain system and the side chain system are both independent chain systems, and they can interact with data according to certain protocols. In this way, the side chain can play a role in extending the functions of the main chain. Functions that are inconvenient to implement in the main chain can be implemented in the side chain, and the side chain can enhance its reliability by interacting with the main chain data.
3. Interconnection chain
Nowadays, our life can be said to be inseparable from the Internet. The energy brought by just being interconnected is already so huge. The same is true of the blockchain. At present, various blockchain systems are emerging, some only implement digital currency, some implement smart contracts, some implement financial trading platforms, some are shared chains, some are consortium chains, and so on. There are so many chains with different functions, constantly refreshing newer application methods, so what chemical reactions will occur if these chain systems can be interconnected between batches? Different from traditional software, blockchain applications have unique properties, such as data immutability, completeness proof, automatic network consensus, smart contracts, etc., from the initial digital currency to the possible future blockchain programmable society. These not only change the way of life and service, but also promote the reform of social governance. If each chain is a nerve, once interconnected, it is like a nervous system, which will bring a new level of intelligence to our social development.
In addition, from a technical point of view, the interconnection in the blockchain system can complement each other. Each type of system has its strengths and weaknesses. It complements each other in function and can verify each other in batches, which can greatly enhance the system’s performance. reliability and performance.