Niels Wang, product development director of the NULS core technical team
*The NULS cross-chain and multi-chain parallel mechanisms have aroused heated discussions in the blockchain technology circles throughout Asia. In the wake of the discussion,*[*Weilaicaijing.com*](https://www.weilaicaijing.com/) *extended a special invitation to Niels Wang for an interview.*
*Niels Wang, product development director of the NULS core technical team, has 10 years of experience in programming and a long history of experience in application research and development. Niels is proficient in blockchain and big data systems as well as large concurrent system architecture. He has participated in e-commerce, IoT and other large-scale projects such as smart environmental protection industry solutions.*
Interview Contents from [WeiLaiCaiJing](https://www.weilaicaijing.com/topicArticle/24863)
**1. We have noticed the recent release of NULS 2.0-Alpha, specifically the NULS cross-chain solution. Why did NULS consider cross-chain functionality in the design and why is cross-chain essential for blockchain?**
**Niels:** Back when the NULS project was initialed, cross-chain and multi-chain parallelism were included in the white paper. Blockchain technology has evolved from the singular design blockchains, like Bitcoin, into the current sea of diverse projects pushing the boundaries of technical innovation. Obviously, there will be more innovation and more blockchains to come and each will carry their own different value and business solutions. Unfortunately, this means that many blockchains will be islands unto themselves.
The development of traditional software industry tells us that no platform or company can cover all business scenarios, and no chain can solve all problems in all industries. So what is the way to truly implement a blockchain application to make a difference in people’s work and life with blockchain development? For the traditional industry, we know that it is the combination and collaboration of applications. While in the blockchain industry, the counterpart is the chain itself that needs to combine and collaborate. To achieve this, value and business should be circulated between the chains.
So cross-chain is the way to get it done. Technically, blockchain is subject to limitations brought about by design. It is highly difficult to achieve the hundreds of millions of transactions per second in traditional distributed software. So, a better design is to put independent business operations on a separate chain and then link the information, transactions and communication. Cross chain can handle all of these and only in this way can we make ten million transactions per second a possibility.
This is why NULS set out to construct a cross-chain ecosystem from the very beginning. Before most projects considered it a priority, we knew it would become the future.
**2. So will the cross-chain function be available in the first NULS 2.0-Alpha?**
**Niels:** The current released version is the first version of NULS 2.0, which is being tested by partners and some active users in the community, and includes incomplete cross-chain functions. As the first alpha release, the testing focuses on “chain-building “ and aims to answer the following questions:
Is the blockchain basic module based on micro-services applicable to chain-building?
Is there any room for optimization?
Is the module completely split?
Is the communication method correct?
Are the system operating parameters appropriate and what adjustments need to be made?
Out of consideration of these purposes, we have not yet provided full cross-chain functions in the first version. But cross-chain code has been included in the next version, and its development and testing are also underway.
The beta release is expected to feature the full cross-chain functionality this May, and at that time we will mobilize the community for more extensive and full testing.
**3. In what way are the cross-chain functions in NULS 2.0 realized?**
**Niels:** The NULS cross-chain structure is a decentralized, high-performance and highly reliable system combining the original POC consensus mechanism with the Byzantine fault-tolerant mechanism.
It uses the NULS 2.0 main network as the core, where all the chains in the NULS cross-chain ecosystem only need to communicate with the NULS main network, leading to less complexity of the cross-chain network and higher security. The cross-chain communication uses the same relay format that the NULS main network uses for relay and verifies the transactions.
NULS defines the basic cross-chain protocols, so any chains following these protocols are capable of accessing features of the NULS cross-chain ecosystem. Blockchains built through Chain Factory, NULS underlying modules, or NULS source code only need to download and run the cross-chain modules to complete the integration with the protocols, which greatly reduces the cross-chain costs, and this handy automation is very friendly to developers responsible for maintenance of the blockchain.
When a cross-chain transaction is initialed by a chain, the chain will verify and package it according to its normal process. The cross-chain module will discover this transaction and convert the original protocol to the NULS cross-chain protocol. Then the cross-chain protocol will be sent to the NULS main network for verification of the transaction. When more than 80% of the POC consensus nodes sign and confirm the transaction, it is deemed to be valid. Then it will be packaged into the main network, and later the transaction receiving chain will be notified for processing and confirmation in a similar way.
For the external chain to have access to the NULS ecosystem, it needs to implement a protocol conversion layer to convert the original protocol to NULS cross-chain protocol. The form of the protocol conversion layer is free of limitation. For example, to connect the Bitcoin network to the NULS cross-chain ecosystem, we can design an intermediary group to verify and confirm the transaction, so as to realize the communication and docking between the Bitcoin network and the NULS network. What’s more, we can design a smart contract to implement the protocol conversion for Ethereum and any others quite easily.
**4. How to initiate a cross-chain transaction on NULS?**
**Niels:** For cross-chain transactions, we hope to offer user-friendly experience on the client-side. For an ordinary transfer transaction, user should just fill in a receiver’s address as well as the amount, and then simply confirm to send. In the same way, the NULS wallet will provide interface invocation, with command line and operation interface to realize cross-chain transactions to make it as easy as ordinary transfer operations without complications. It’s as easy as any other standard transaction. This helps to avoid any additional user threshold. It also means cross-chain transactions can be conducted from basically any wallet or hardware devices, such as Ledger and Trezor.
**5. Compared with other public chain projects, what do you think is the biggest feature or competitive advantage of the NULS cross-chain function?**
**Niels:** The characteristics of the NULS cross-chain can be summarized in the following:
- **Decentralization**: the centralization scheme is never an option for the NULS cross-chain. The network is deeply involved in the verification of the transactions which should always be confirmed by the distributed nodes. It is strongly opposed that several nodes or one group can represent a chain.
- **Easy to implement:** any chain inside the NULS ecosystem only needs to download and run a cross-chain module to achieve all the functions required by the cross-chain, and the external chain only needs to design and implement a protocol conversion layer depending on its own situation. For chains that run on Chain Factory, the download is completely automated and runs instantly.
- **Security:** POC consensus mechanism and Byzantine fault-tolerant algorithm jointly ensure the validity of the cross-chain transaction confirmation, so a confirmed transaction is never lost. Each chain will record the amount of other chain assets held in the main network. So, even if the whole chain decides to be a bad actor, it will not affect the other chain thus ensuring risk isolation.
- **High efficiency**: cross-chain settlements can be confirmed in less 5 minutes and as more chains become part of the ecosystem, this time is reduced even further.
- **Ecosystem**: asset circulation, business circulation, asset exchange, and support for various extended business scenarios.
**6. Since the implementation of cross-chain functions is very complicated, do you encounter any difficulties in this process and how did you overcome them?**
**Niels**: Cross-chain is a mechanism of great complexity, and the difficulties in the design and development mainly are as follows:
- Decentralized verification of cross-chain transactions; how to ensure that the assets transferred out of the blockchain will not be double spent, how to keep fees charged for cross-chain transactions to a minimal, and how to realize cross-chain for chains outside the NULS ecosystem, etc.
- NULS’s decentralized verification is to connect as many nodes as possible in each chain, and realize the confirmation of the cross-chain protocol through distributed verification.
- For double-spending issues, the NULS ecosystem adds a protocol with two bytes length to all addresses to identify which chain they belong to. When an asset is transferred from chain A to chain B, the corresponding rights are also taken over by B. At this point, A will destroy the asset to ensure that double spending is impossible.
- Transaction fees are divided into three parts: the initiating chain, NULS, and the receiving chain. In our design, the initiating chain can freely determine the type of fees charged. For the NULS and receiving chain, only NULS is charged as a handling fee for the purpose of unified use. And the two distribute the fee provided by the transaction initiator proportionally.
- For the chain outside the NULS ecosystem, NULS uses a protocol conversion layer to realize the conversion of different protocols and NULS cross-chain protocols, which solves the problem of how to connect the NULS ecosystem with Bitcoin, Ethereum and others. There are still a number of problems in cross-chain design and development. Although many projects in the industry claim to support cross-chain, only a few have actually built the cross-chain network. NULS upholds the spirit of innovation and pioneering, and we never give up until we reach the goal.
**7. In the publicity, you mentioned that “the era of cross-chain value circulation has come”. What do you think of it? And what role does NULS play in this process?**
**Niels:** Since the emergence of the blockchain concept behind Bitcoin, numerous blockchains have been created. Each of them focuses on their own use-case functionality, and the value is only circulated within their own business operations and application. But now, almost every blockchain intends to achieve cross chain functionality. Only the value circulation can enhance this growth which needs more recognition and application scenarios. NULS in this trend has made early advancements to implement the value circulation, all the while lowering the chain-building threshold, and also reducing the cost of value circulation. This is significant acceleration offered by NULS to fast track the development of the blockchain industry. **NULS positions itself as a participant and facilitator and will certainly challenge the leading projects of the future. This cannot be emphasized enough — microservices design facilitates the ability to add innovation and adaptation in record time, with ease. In open-source software development this is an extreme advantage.**
**8. What kind of enterprises/institutions do you think need cross-chain functions? What can NULS offer them? Or why would they definitely choose NULS?**
**Niels**: I think blockchains and cross-chain scenarios are common requirements for all enterprises and institutions, but it depends on their specific needs and determinations, which is hard to define clearly. NULS can provide services as long as you want to use blockchain to solve the problems of trust, value circulation and business circulation in your business.
NULS has been dedicated to promoting the implementation of blockchain enterprise solutions since its establishment. It can provide users with appropriate solutions in terms of building the underlying blockchain network, extending business functions and cross-chain circulation of value and business operations. The module repository of NULS includes a lot of basic modules applicable to various scenarios of different sizes and types of businesses. Users can get the customized services that meet their own needs in a simple, efficient and low-cost way. So if you are an enterprise, why wouldn’t you choose NULS?
**9. Has any enterprise docked with NULS yet?**
Niels: Currently NULS cross-chain solution is still in the internal testing, so we have not started to dock with the other blockchain projects. However, many domestic and foreign enterprises have signed cooperation agreements with us, including partners such as Prism, SuperLinks and Hena. These enterprises have also participated in the NULS 2.0 test, and provided important and valuable feedback. We have also optimized the underlying implementation based on these to improve the whole NULS ecosystem and make full preparations for future docking.
**10. What do you think about the future cross-chain ecosystem of NULS?**
Niels: NULS plans the cross-chain ecosystem with pretty forward-thinking ideas. It brings more imagination to the development and application of the blockchain industry. Around these functions of chain-building, smart contract and cross-chain, it can build a blockchain interconnected ecosystem of value, business and trust, and provides strong support for application implementation to enable people to enjoy the security, transparency and convenience brought by blockchain more quickly. NULS and blockchain will help push our society into a new era.
*Learning from the interview of Niels Wang, product development director of the NULS core technical team, it is easy to find that from the original intention to the ideals of the whole team, NULS is very proactive and ground-breaking. The team will not be satisfied to stop at the current advancements in technological development of blockchain and will continue to be a force of innovation, which is very rare amid the current industry. NULS leads and does not follow.*
*Finally, I thank the NULS core team for their professional answers. We hope that NULS can continually accelerate technological output and make more leaps in cross-chain collaboration. We are looking forward to what else NULS can offer to further empower the industry and other blockchains, as well as providing more efficient, safer and more convenient comprehensive business services for the public and enterprises based on cross-chain technology.*
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