Most of the blockchain platforms have scalability issues that lead to slowing down of the network in case of too many transactions. It was clearly seen on the ethereum network when cryptokitties caused network congestion. As of now, Ethereum supports 15 txs/sec which is not fast enough. IOTA solves this issue by supporting 1000txs/sec which is needless to say much more than currently provided by ethereum. Now, IOTA is mainly focused on IOT and it’s use cases. Not only that, severe cryptographic vulnerabilities have been found in it.
ZILLIQA-
“ZILLIQA is a high-throughput public blockchain platform designed to scale to thousands of transactions per second”, as stated on their website and it is backed by its test on its private test net reached 1,218 transactions per second with only 1,800 full nodes. If you double the nodes to 3,600 the throughput scales as well to 2,488 transactions per second.
Source- zilliqa.com
Zilliqa’s Solution
Scalability:
Zilliqa is attacking the scalability issue with their own solution that allows more transactions to be processed as more nodes enter the network. It basically rebuilds the blockchain architecture from scratch. The model they’re using has a hybrid consensus protocol that will increase throughput with every additional 600 nodes in the network.
Zilliqa’s blockchain works by dividing the work done on the network, with throughput increasing for every 600 new nodes. This is in theory. In practice, they are finding problems with broadcast once the network scales to more than 1 million nodes. However, we are currently nowhere near this level on any existing blockchain. Ethereum, which has the largest network of nodes, currently has roughly 25,000 full nodes. The Ethereum network, with its 25,000 full nodes, is only capable of processing 15 transactions per second.
This technique of dividing the network is known as network sharding. Ethereum is also moving towards sharding but it’s different from zilliqa’s sharding, ethereum will use state sharding.
Less energy intensive to mine
Another major plus that comes with Zilliqa is the reduction in the overall energy footprint when mining the cryptocurrency. The capability is a consequence of the implementation of a Proof-of-Work system. PoW defends against Sybil attacks and is also used to perform network sharding. Unlike other PoW-based blockchains, ZILLIQA does not use PoW for consensus. PoW is performed only at larger intervals, not by every miner on every block. Thus, ZILLIQA has a much smaller energy footprint.
Instead of PoW, ZILLIQA uses an optimized practical Byzantine Fault Tolerant (pBFT) protocol for consensus.
There are several advantages of using pBFT as a consensus protocol:
- It is not computationally intensive and hence less energy-consuming than PoW.
- It can leverage a small consensus group for efficiency.
- It gives finality to transactions. In other words, unlike PoW-based consensus, where usually 6 confirmations are required, pBFT guarantees that no temporary fork will happen due to the consensus protocol and hence, no confirmation is required.
The potential in these results is astounding, but how does Zilliqa do it?
They are using a solution called Sharding which with Zillqa works by dividing the network into groups of 600 nodes, with each group known as a shard.
For example, when Zilliqa ran the above-mentioned test on their testnet with 1,800 nodes these were divided into 3 shards. When increased to 3,600 nodes there are 6 shards. Each new group of 600 nodes creates a new shard in the network.
The shards divide the work being done on the network, with each shard responsible for just a portion of the network transactions. So, if you get 10 shards, each shard is only concerned with processing 10% of the network transactions. And as the network grows, more shards become available, dividing the load further and keeping computing demands for each shard fairly stable.
Each shard creates a microblock with the transactions it processes. All of the shards process these transactions in parallel, and at the end of the parallel processing period, called the DS Epoch by the Zilliqa team, the microblocks are combined to form a full block. That full block is then added to the blockchain.
Each DS Epoch has a DS Committee as well. This is a small group of several randomly selected nodes which act to manage all the other shards. The DS Committee decides which transactions get assigned to which shards.
And once the microblocks are created, the DS Committee is responsible for creating the full block and committing it to the blockchain.
In a blog post, it is estimated that only 12 hours of operation at full capacity will be required of GPU cards monthly, allowing them to run idly for the remainder of the time. It is expected to lead to electricity costs of almost a tenth of those associated with Ethereum mining.
Zilliqa smart contract language (Silica)
To accomplish their goal of standardized and secure functional programming, Zilliqa developed the Scilla programming language. The concept behind the style is to separate the state and the function to distinguish the different communication aspects of a smart contract.
It’s fairly straightforward to shard transactions on a blockchain. Transaction verifications are easily assigned to different shards, and each verification stands on its own. Shards have little need to communicate between themselves thanks to the DS Committee.
However, this can’t be said for smart contracts and Dapps run on a sharded blockchain. A smart contract often relies on external sources of data, functions, and other variables. To do this on a sharded blockchain would require potentially massive amounts of communication between the shards. The bandwidth and processing power consumed by this communication would make the benefits of sharding null.
Because of these limitations, the contracts in Zilliqa are focused on functional programming and data flow — at least for the time being. But the team is working on a way to allow for state changes, storage, and data checking.
The current state of blockchain technology has led to a widespread opinion that state sharding can’t be made efficient and secure. If contracts were executing separately in sharded states it would leave the network open to all types of potential attacks, as well as cross-shard contamination, and possible challenges for the reconciliation of transactions.
That said, Ethereum’s sharding solution is a state sharding solution, although ethereum has not announced yet that when it might be ready for deployment.
Scilla focuses on making functional programming more secure and standardized, and it does this by separating state and function. In other words, it is a programming language that can differentiate between the actual computational work of a contract and the communication aspects of the contract.
One downside to the Scilla language is that it is not Turing complete, and can’t be used to create applications that require conditional statements and certain types of loops. It does remain subject to formal logical proofs, and this is key to security. It allows users to verify a contract is safe before using it, which is one of the keys to widespread adoption.
More specifically, Scilla is capable of solving security and development problems in the smart contract ecosystem. Furthermore, this new language will allow for developers to build smart contract-based applications on any blockchain, regardless of whether it’s public or private. This means that Scilla will essentially be competing against Solidity for Ethereum, but that may not necessarily be a bad thing.
As of right now, a smart contract can be written in a wide variety of programming languages, of which Solidity is the most popular despite being rather complicated. Scilla, on the other hand, is more forgiving for newcomers and coding veterans alike. It is even possible to “convert” code written in Solidity to Scilla. With the new language providing multiple layers of separation for communication and operational aspects, it is certainly worth looking into. Compartmentalizing various components of smart contract coding will hopefully help thwart any attacks made against smart contracts in the future.
Zillica Team
The Zilliqa team is comprised primarily of PhDs in computer science with an academic background. In fact, Zilliqa was born from an R&D project of the National University of Singapore and more than two years of work had a functioning blockchain before the Zilliqa ICO.
The CEO of the project is Xinshu Dong, who completed his Ph.D. at the National University of Singapore. Since then he has been a leading cybersecurity expert, working on a number of security projects for the Singaporean government.
Conclusion
Scalability will remain an issue for blockchain technologies for the foreseeable future. While existing blockchain projects are looking for a workaround that likely won’t provide more than a short-term solution, the team at Zilliqa is taking a different approach and tackling the issue head-on, with a unique and innovative approach.
While Zilliqa may not have the ultimate solution yet, it is sure to be an important step in blockchain technology, and there’s good chance its development of sharding technology will come into play in numerous future blockchain projects.
