The Ethereum blockchain faces a major scalability issue, hindering its adoption on a global scale due to limitations in speed and capacity. In August 2017, Ethereum co-founder Vitalik Buterin and Joseph Poon proposed the Ethereum Plasma as a solution to this issue. The Plasma concept is a scaling technique for the Ethereum blockchain, similar to the Lightning Network proposed for Bitcoin in 2015 by Joseph Poon and Thaddeus Dryja. However, each has its own mechanisms and particularities. Keep in mind that Plasma is not a project, but an off-chain scaling technique or framework for building scalable applications. Different research groups or companies can implement it in various ways.
How Does Plasma Work?
A framework of secondary chains is the core concept behind the Ethereum Plasma. The aim is to limit the interaction between the secondary chains and the main Ethereum chain as much as possible. To achieve this, the Plasma framework will be set up as a blockchain tree, with smaller chains built on top of the main one, known as Plasma chains or child chains. It is important to note that Plasma chains are different from sidechains.
Smart contracts and Merkle trees are used to construct the Plasma structure, making it possible to create an infinite number of child chains. Each child chain is a miniature version of the Ethereum blockchain. Multiple chains can be built on top of each child chain, creating a tree-like structure.
In essence, every Plasma child chain is a customizable smart contract that operates independently, tailored to different requirements. This implies that the chains can coexist and serve unique purposes. Ultimately, Plasma will enable businesses and organizations to implement various scalable solutions based on their context and needs.
If Plasma is successfully integrated into the Ethereum network, the main chain will be less prone to congestion since each child chain is tailored to work towards specific goals, which may not be linked to the main chain's objectives. Consequently, child chains will relieve the main chain's workload.
Fraud Proofs
The root chain is responsible for securing the communication between the child chains and itself by employing fraud proofs to punish any malicious actors. Each child chain operates independently with its own mechanisms for validating blocks and a particular fraud-proof implementation. These fraud-proof implementations can be built on top of different consensus algorithms such as Proof of Work, Proof of Stake, and Proof of Authority.
The purpose of fraud proofs is to allow users to report dishonest nodes in the event of malicious activity. Users can then protect their funds and exit the transaction, which involves interaction with the main chain. In essence, fraud proofs serve as a mechanism for a Plasma child chain to file a complaint with its parent chain or the root chain in case of any fraudulent behavior.
MapReduce
One interesting application presented in the Plasma whitepaper is the use of MapReduce computations. These computations are a set of functions that are useful in computing and organizing data across multiple databases. In the case of Plasma, these databases are blockchains, and the tree-like structure of the chains allows for the application of MapReduce. This enables the verification of data within the tree of chains and greatly increases the network's efficiency.
Mass Exit Problem
The possibility of a Mass Exit problem is one of the main concerns associated with the implementation of Plasma. This problem occurs when many users simultaneously attempt to exit their Plasma chain, causing congestion on the root chain. There are various reasons why such a situation could occur, ranging from fraudulent activity to network attacks or other critical failures that may arise in a single Plasma child chain or group of chains.
Conclusion
Plasma is a solution that aims to enhance the performance of Ethereum by creating a tree-like structure of smaller chains. This would reduce the load on the main chain, enabling it to handle more transactions per second. Many research groups are currently testing this hierarchical model of linked blockchains. With proper development, Plasma could improve the efficiency of Ethereum and provide a better framework for decentralized applications. Additionally, this idea may be implemented by other cryptocurrencies to avoid scalability problems.