IoTeX Mainnet Preview (Photon) Release
Posted by Lori a month ago

Hello IoTeX community! Since our last code release in August, the IoTeX team has made great strides in research, proofs of concept, and community growth. Most importantly, we have made incredible progress on technical development and are one step closer to our goal of building the most secure, usable, and performant blockchain platform in the entire industry. Today, we are proud to launch our fourth code release – Mainnet Preview “Photon” – which includes exciting new features that preview our full-feature Mainnet Alpha launch in Q1 2019:


  • Sub-chain provisioning: support of two independent blockchains (root chain, sub-chain), running on separate databases in the IoTeX network
  • Cross-chain communication: ability to transfer value from root chain to sub-chain, with IoTeX Wallet support across both chains
  • Consensus enhancements: performance enhancements to Roll-DPoS (1,000+ TPS & 100+ node tests), and new security improvements
  • IoTeX Explorer v2.0: separate IoTeX Explorer pages to visualize both root chain and sub-chain activities
  • And much more!

You can see the open source code on our Github now. Detailed instructions for running the Photon code are provided in this README file, and a detailed demo video can also be found here: https://youtu.be/Ql4kCX282U4 .


Why “Photon”? — Kenneth Lane Thompson

Photon is named after Kenneth Thompson (Photon is composed of letters from “Thompson”), following the trend of naming IoTeX’s code releases after pioneers of computer science. Earlier this month, we gave our community the chance to propose and vote for the Mainnet Preview codename. We received over 12,600 submissions and out of five finalists, Photon was the unanimous winner with 27% of total votes. Thanks to all who participated! We will announce the full winner lists soon!



Kenneth Thompson is an American computer science pioneer. He is best known for inventing several programming languages (e.g., Go, B) and operating systems (e.g., Unix) and received the Turing Award in 1983. As you may know, the IoTeX blockchain is coded in Go (co-invented by Thompson) – naming this release “Photon” is a tribute to Thompson’s work, which provides the building blocks for IoTeX to innovate today.


Photon Overview & Features

In Photon, we preview some new technological concepts that will be fully deployed in our Mainnet Alpha release in Q1 2019. IoTeX’s goal is to create a blockchain that can support all types of Internet of Things (IoT) use cases – smart cities, supply chain, wearables, autonomous vehicles, and more. Although they share common requirements (i.e., scalability, privacy, IoT device support), each use case is unique and requires a tailored approach to optimize performance and security. To accommodate this diversity, IoTeX’s utilizes a root chain / sub-chains architecture that will allow developers to create custom sub-chains using the design that best suits their DApps. Applications will seamlessly exchange value / data with other applications via cross-chain communication. This is our vision for the future of IoT – a vibrant ecosystem of fit-for-purpose and interoperable sub-chains powered by IoTeX.

Over the past two months, we have developed several in-house innovations which bring us closer to our vision for the future of IoT. The core features of Photon, which we detail in the following sections, include sub-chain provisioning, cross-chain communication, consensus (Roll-DPoS) enhancements, and IoTeX Explorer v2.0. Through exhaustive code reviews / “quality weeks”, we have greatly enhanced the stability of our smart contracts, wallet, and existing code base. Finally, we have rigorously tested the IoTeX Testnet and have achieved 1,000+ TPS (with instant finality) and successfully deployed 100+ nodes using Kubernetes. The full list of Photon features and enhancements is shown below:


Sub-chain Provisioning and Management

The root chain / sub-chain architecture is a core part of IoTeX’s blockchain design, allowing any user to create their own sub-chains with the architecture, programming language, and even consensus mechanism that best suits its purpose. For example, a privacy-focused sub-chain would benefit from a Mimblewimble architecture, while a sub-chain requiring higher throughput may utilize bigger blocks. Not only do sub-chains add flexibility for developers, but they also add scalability. You can think of sub-chains as separate blockchains running in parallel, where activity on one sub-chain does not affect throughput on other sub-chains. Their states (i.e., history of transactions) are periodically synced to the root chain, which records the state of the entire IoTeX network. With the ability to add unlimited sub-chains, the IoTeX network is practically infinitely scalable.

In Photon, we introduce our FIRST root chain / sub-chain pair, which are separate, homogeneous blockchains running on separate databases. They share some P2P networks but are otherwise independent, meaning transactions on the root chain and sub-chain are logged on separate ledgers and each will produce blocks in parallel. While sub-chains are flexible and customizable, the root chain is more rigid and performs specific roles. In the IoTeX network, one of the roles of the root chain is to record the state of each sub-chain at various points in time (blocks), which is detailed in the following diagram.

Every block of a sub-chain contains various types of transactions, including token / data transfers and smart contract executions. As with every blockchain, a block is produced and verified (“mined”) after the max block gas limit is reached. In addition, the digest of transactions  of the sub-chain is recorded on the root chain for every new block created. This is accomplished by reporting a hash root (aka Hash ID in the diagram above) of the Merkle tree of transactions every time a sub-chain block is mined; put simply, a Merkle tree is a hierarchical representation of the history of a blockchain’s transactions at a certain point in time. Every new block will have a unique Merkle tree and therefore a unique Hash ID, which is sent to the root chain as a proof of what happened on the sub-chain since the last block.

Root chain transactions consist of votes for delegates, cross-chain transfers of value / data (described in the next section), and Hash IDs of various sub-chain blocks, which represent snapshots of transaction history of all sub-chains in the IoTeX network. As shown in the figure above, Block 3 of the root chain contains several cross-chain transactions (i.e., Hash ID (cross-chain)) as well as the Hash IDs of several sub-chain blocks (i.e., A, B, C, X-2, X-3). “X-2” is the state of sub-chain X-2 after its second block, “X-3” is the state of the sub-chain after its third block, and the state of sub-chains A, B, and C are also recorded. Depending on the amount of transactions generated on a sub-chain (i.e., the rate at which it produces new blocks), multiple Hash IDs of sub-chain blocks can be stored in the same root chain block.

The end result is massive scalability. With a normal blockchain architecture, all of sub-chain X’s transactions would be stored individually on the root chain. With IoTeX’s architecture, we can effectively store an entire sub-chain block as a single transaction on the root chain, enabling “100-to-1” scalability. With the ability to add unlimited number of parallel processing sub-chains, the IoTeX network will be able to support billions of IoT devices in the future.


Cross-chain Communication (CCC)

Cross-chain communication, which enables interoperability across blockchains, is a widely researched topic in the blockchain industry. Projects such as Polkadot, Cosmos, and Aion have varying approaches to building an interoperable network of blockchains. This concept of interoperable blockchains (i.e., IoTeX sub-chains) is a core component of our vision for the future of IoT. Today, IoT devices and companies operating on various cloud-based platforms (e.g., AWS, Google, Azure) cannot exchange data, which greatly restricts the value and capabilities of IoT. Enabling interoperability between unique and complex IoT industries is a core focus of IoTeX, which is why our upfront design decisions are centered around support of heterogeneous sub-chains and cross-chain communication.

In Photon, we preview cross-chain communication capabilities between the root chain and sub-chain, which are independent blockchains. Over the past months, we have researched and developed building blocks to enable two-way transfers of data and value (i.e., tokens) between root chain / sub-chains – we plan to release research papers in the coming weeks and fully deploy cross-chain communication in our Mainnet Alpha launch. For our Photon release, we preview some of these building blocks:

  • Token deposits from root chain to sub-chain: transfer EIOTX tokens between independent blockchains (i.e., root chain and sub-chain) via an Explorer API call
  • Upgraded IoTeX Wallet: utilize a single wallet for both root chain and sub-chain (i.e., different account addresses, same private key), with separate token balances



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