Research Progress of Heterogeneous Blockchain Data Migration

Technology

Yutong Xie

1,2,* a

, Shuai Chen

1,2 b

and Xinnan Wang

2,3 c

State Grid Digital Technology Holding Co., Ltd., Beijing China

State Grid Blockchain Technology (Beijing) Co., Ltd, Beijing, China

Blockchain Technology Laboratory of State Grid Corporation of China, Beijing, 100053, China

Keywords: Blockchain, Blockchain Data Migration, Heterogeneous Blockchain.

Abstract: In recent years, with the rapid development of blockchain technology, blockchain underlying architecture,

algorithm and other technologies are constantly upgraded. The upgrade of technology drives the innovation

of business. The old blockchain cannot meet the demand of new business, so it is necessary to carry out

application update and blockchain data migration. However, due to the immutability and other characteristics

of blockchain technology, it is very difficult to migrate data on the blockchain. At present, due to the lack of

effective migration mechanism, there are a series of problems in the process of blockchain data migration,

such as inconsistent structure of heterogeneous blockchain blocks and transaction data, modified proof of

existence of data, and difficult migration of smart contracts. Therefore, the research of heterogeneous

blockchain data migration technology is very important. This paper analyzes the current domestic and foreign

researches on the unified abstraction of heterogeneous blockchain data structure, transformation of smart

contract, proof of the existence of data and other technologies, and focuses on the basic problems such as

cryptography algorithm, smart contract and blockchain data structure, and puts forward the technology of

transferring heterogeneous blockchain block and transaction data, smart contract code and status data, so as

to provides ideas for solving the problem of heterogeneous blockchain data migration and promote the further

development of blockchain technology.

1 INTRODUCTION

In the development process of blockchain, due to the

continuous emergence of new technologies, and there

is no standard way to implement blockchain, both the

public chain and the alliance chain have appeared the

phenomenon of contention. With the evolution and

replacement of technology, it is inevitable to upgrade,

replace and migrate the original blockchain system.

In this process, the data of the original blockchain

application needs to be secure and available.

However, due to the characteristics of blockchain

technology, data migration on the blockchain is very

difficult. Heterogeneous blockchain data migration

has seriously threatened the sustainable and healthy

development of blockchain technology. At present,

https://orcid.org/0000-0002-8003-4176

https://orcid.org/0000-0003-2377-4000

https://orcid.org/0000-0002-9246-4819

due to the lack of effective migration mechanism, The

following problems exist during data migration.

 Heterogeneous blockchain block, transaction

and other data structure is inconsistent, the data

structure is difficult to convert.

 The existence proof of the original data is

modified and the authority of the data is destroyed.

 Heterogeneous blockchain smart contract

migration is difficult and it is difficult to verify the

function consistency of smart contract.

 Heterogeneous blockchains provide

incompatible interfaces.

With the practice and development of blockchain

technology, State Grid Corporation of China has put

forward higher requirements for the promotion and

application of blockchain prospective technology,

further deepening the research on blockchain

548

Xie, Y., Chen, S. and Wang, X.

Research Progress of Heterogeneous Blockchain Data Migration Technology.

DOI: 10.5220/0012036600003620

In Proceedings of the 4th International Conference on Economic Management and Model Engineering (ICEMME 2022), pages 548-554

ISBN: 978-989-758-636-1

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

technology, improving the independent mastery of

core technology, and strengthening the application in

more businesses of State Grid Corporation of China,

such as energy trading (Zhang, Hou 2021), energy

metering, etc.

On the basis of investigation and research, this

paper puts forward the independent controllable

heterogeneous blockchain data migration technology,

which combined with proof mechanism of

cryptography and data migration technology, solving

the data migration problems that may occur in the

process of heterogeneous blockchain upgrade and

replacement, realizing the high availability of data in

the process of blockchain upgrade, replacement and

data migration, and improving the compatibility and

collaboration between blockchain systems.

2 BLOCKCHAIN OVERVIEW

Blockchain originates from Bitcoin (Satoshi

Nakamoto 2008) and is the underlying technology of

Bitcoin. Bitcoin is the earliest application of

blockchain technology. Blockchain is a distributed

ledger that uses cryptography to append blocks

confirmed by consensus in sequence. As the name

implies, in terms of data structure, blockchain is a

blockchain structure that uses hash Pointers instead of

traditional Pointers. Each block contains a block

header and a block body, the block header contains

the version number, the hash value of the previous

block, the root hash of the Merkle tree of the block,

the timestamp of the generated block, the difficulty

value, and the random number. The block body

contains the transactions recorded in the block.

Blockchain relies heavily on encryption algorithms,

peer-to-peer communication technologies, and

innovates the smart contracts (Vitalik Buterin 2013)

implemention. The organic combination of various

technologies gives blockchain features such as

decentralization, immutability and traceability.

Blockchain is divided into public chain, alliance

chain and private chain, with the degree of openness

decreasing successively. At present, alliance chain

has a wide range of landing scenarios in China.

As a brand-new information storage,

dissemination and management mechanism,

blockchain technology has attracted great attention in

various fields. In recent years, with its potential value

and favorable policies, the blockchain industry has

ushered in the best opportunity for industrial

development, and the blockchain technology has also

ushered in continuous development and innovation.

By May 2019, more than 30 provinces and regions in

China have issued policy guidance documents and

carried out the layout of blockchain industrial chain,

combining blockchain technology with local

characteristics, which playing a positive role in

serving economic and social development.

Blockchain, as an emerging technology, has come

into public view and become the focus of social

attention.

With the development and in-depth application of

smart contract technology, blockchain, as a ledger,

has a strong programmable ability, which has

broadened the original simple transaction function,

and started to realize more complex functions such as

complex conditional payment, business logic,

automatic execution of scripts, multi-party

agreements that conform to legal relations.

In China, enterprise application is the main

battlefield of blockchain, and alliance chain are

widely used. In the coming period of time, blockchain

applications will be used to reduce costs, improve

collaboration efficiency, and stimulate real economic

growth. Different from the public chain, in enterprise

applications, people pay more attention to the control,

regulatory compliance, performance, security and

other factors of blockchain.

3 RESEARCH STATUS OF

HETEROGENEOUS

BLOCKCHAIN DATA

MIGRATION

At present, there are three kinds of technologies in the

field of heterogeneous link data migration. First, how

to unify and abstract the data structure of blockchain.

It is necessary to study the differences in data

structures of different blockchains, and conduct

unified abstraction of data structures to build a unified

data interface layer for the convenience of

management of the business layer, so as to solve the

compatibility problem of business layer caused by

different data structures of heterogeneous

blockchains in the process of data migration. Second,

how to complete the migration of heterogeneous

blockchain smart contract. It is necessary to study the

current smart contract technology of heterogeneous

blockchain, and explore how to achieve smart

contract migration. The third is the difference of

existence proof of different heterogeneous

blockchain data.

Research Progress of Heterogeneous Blockchain Data Migration Technology

549

3.1 Unified Abstraction Approach for

Heterogeneous Blockchain Data

Structures

In terms of the unified abstraction of heterogeneous

blockchain data structure, there are many cross-chain

protocols. Cross-chain protocol (Li, Qiu, Xu, Song,

Liu 2021) is usually a trusted source oriented

interoperation protocol, aiming to build a set of

flexible, unified, reliable interoperation protocol, to

achieve convenient access and reliable operation to

different trusted sources. Trusted sources refer to

software, hardware, or other types of entities that can

provide trusted data. Trusted sources can be

distributed or centralized. Common trusted sources

include blockchain, oracle machine and so on.

The unified abstraction protocol in cross-chain

protocol includes four protocols that define the

unified abstraction among trusted sources, account

services, cross-chain routes, and applications. As

shown in figure 1.

 Unified Account Protocol: A unified

abstraction of various trusted sources accounts,

enabling the operation of different trusted sources

with a unified account.

 Unified Addressing protocol: A unified

abstraction of various trusted sources smart contracts

(chain codes) and other operable objects to achieve

unified addressing with the concept of "resources".

 Unified Invocation Protocol: A unified

abstraction of the various trusted sources invocation

protocols to invoke resources with a unified interface

and parameters.

 Unified Access Protocol: An abstraction of

various trusted source access protocols to implement

unified access adaptation of different trusted sources.

Different trusted sources develop plug-ins based on

this protocol to achieve adaptation and access.

Figure 1: The unified abstraction protocol.

3.2 Transformation of Heterogeneous

Blockchain Smart Contract

Smart contract can be regarded as a computer

program running on the blockchain with preset rules,

with status and conditional response, which can

encapsulate, verify and execute complex behaviors of

distributed nodes, and realize information exchange,

value transformation and asset management. The core

component of smart contract is smart contract

programming language and its execution engine. The

smart contract of blockchain needs to run in a

completely isolated environment to ensure effective

resource isolation between contracts, and between the

contract and the host system, so as to ensure its

controllable security. Blockchain virtual machines

are one of the ways to execute blockchain smart

contracts. Different smart contracts have different

levels of security and richness of expression.

At present, the research of smart contract code

transformation at home and abroad is still in an early

stage. There are two main reasons: new technologies

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keep emerging, and the original contract language is

also changing. For example, Solidity itself, the

Ethereum smart contracts language, comes out with

new versions and changes every once in a while. Now

the main smart contract transformation is still in two

categories. One is the transformation of Solidity

language into WASM (Yang, Liu, Li, Zheng, Wang,

Chen 2020) intermediate code, such as foreign Yul,

which is an intermediate language only for Ethereum.

Solidity compiler compiles Solidity source code into

an intermediate representation of Yul and then

converts it into EVM instructions. It is finally

converted to bytecode. In addition, RuneEVM makes

the EVM interpreter compatible with the interface of

WASM, so that the EVM contract can be run on

WASM. But both projects are currently inactive. The

other is to compile EVM code into RISC-V

instructions. Currently, some teams using RISC-V

(Waterman, Lee, Patterson 2014) as virtual machines

are doing related research, such as Nervos blockchain

in China, but it is still in an early state.

3.3 Proof of Existence of

Heterogeneous Blockchain Data

At present, the mainstream blockchain mainly proves

the existence of Merkle Trees, but in a few

blockchains, such as Fabric, there may be no relevant

cryptography proof, which requires corresponding

measures during the processing of data migration. In

Fabric, every transaction needs to meet some

predefined endorsement policy. When a transaction is

executed, it will be signed by multiple endorsement

nodes. When the signatures of all parties meet the

endorsement policy, the transaction will be

considered valid. Fabric stores the endorsement node

signature information in the block as part of the

transaction. Multiple transactions make up a list of

transactions within a block. The transaction list

computes a hash value in binary form, which is

recorded in the block header. WeCross cross-chain

protocol of WeBank in China has been studied in this

area. As shown in figure 2.

 Block continuity verification: FISCO BCOS

verifies that this block is the block of the other

bolckchain by comparing the parent block hash in the

block header with the real parent block hash.

 Block consensus verification: By checking the

signature list of the current block, we can judge

whether the number of legitimate signatures meets the

PBFT consensus condition, and confirm that the

current block represents the overall will of the other

blockchain.

 Transaction existence verification: By

verifying that the Merkle Path of the transaction hash

to the transaction root is correct, we can know

whether the transaction already exists on the

blockchain.

 Transaction correctness verification: By

verifying the correspondence among business

expectation, transaction binary, and transaction hash,

we can know whether transaction is the operation

expected by the business.

Figure 2: The verifications of existence.

Research Progress of Heterogeneous Blockchain Data Migration Technology

551

4 APPORACH OF

HETEROGENEOUS

BLOCKCHAIN DATA

MIGRATION

For blockchain, there are mainly two types of data,

block and transaction data, and contract code and

contract status data. The block contains the signature

of the consensus node and the transaction contains the

signature of the user, both of which are the basis of

the blockchain's history. The contract and contract

status are calculated by the node based on the

transaction records.

This section proposes a heterogeneous blockchain

data migration method. The blocks and transactions

of the original blockchain are extracted and loaded

into the traditional database. Each consensus node

stores the full block and transaction data respectively,

and queries and verifies the block and transaction data

through the consensus node of the original

blockchain. After ensuring data consistency, the hash

of the last block of the source blockchain is stored in

the new blockchain genesis block, and the height of

the block is added on the basis of the height of the last

block of the source chain, so as to ensure the

continuity of the block and reach a consensus on the

signature of the Genesis block file. When the height

is less than the height of the Genesis block, search the

target block from the block database.

4.1 Migration of Blockchain and

Transaction Data

For block and transaction data, the transaction

contains the signature of the transaction sender, and

the block contains the signature and time stamp of the

consensus node, which determines that the

transaction and block data are the unchangeable basis

of the blockchain. If the data of the original

transaction and block are reconstructed and migrated

to the new blockchain, the invariance characteristics

of the blockchain will be inevitably modified.

Therefore, this block and transaction can be

synchronized to a separate database for storage,

which includs structured database, KV, file database.

At the same time, in the generation process of the

new blockchain genesis block, the hash of the

previous block of genesis block is the hash of the last

consensus block of the original blockchain, and the

height of Genesis block is increased by one on the

basis of the original blockchain height. In this way,

the new blockchain is connected with the old

blockchain, and the old blockchain data is not

falsified.

The historical height of block chain can be read

directly from the database, and the new height can be

obtained from the new block chain. Users can obtain

signatures in blocks, signatures in transactions, and

generate MPT proofs using block and transaction data

to prove that data has not been falsified. At the same

time, the replay of historical transactions can be used

to generate the historical state, and the authenticity of

the historical state can be verified by the state root and

other related fields in the block. As shown in Figure

Figure 3: The technical principles of migration of blockchain and transaction data.

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4.2 Migration of Smart Contract Code

For smart contract code, if the original blockchain and

target blockchain use the same virtual machine, the

smart contract code can be directly written into the

initial file of the genesis block of the new blockchain

and given the contract its original address, so that the

original contract exists in the new blockchain when

the new blockchain is started.

For target blockchain using different virtual

machines, it is necessary to realize the translation of

contract languages, which can be divided into manual

translation and automatic translation. For manual

translation, the implementation personnel need to

manually write code according to the original contract

logic. For automatic translation, it is necessary to use

existing tools. For example, solidity2wasm already

has the related tools. Or users can write automatic

translation tools by themselves, through which the

original contracts on the blockchain can be translated

and initialized into the genesis block. As shown in

Figure 4.

Consistency verification is required for both

manual and automatic translation to ensure that the

contract logic is consistent. It is necessary for the

implementer to write the test case dataset according

to the original contract, and write the test code

according to the original contract and the new

blockchain contract respectively. When the code

coverage of the test case dataset is high enough, the

consistency of the contract can be guaranteed to a

certain extent. At the same time, when the new

blockchain contract does not meet the expectations of

the original contract, the new blockchain provides the

contract update function to ensure that the new

blockchain contract can finally maintain the

consistency with the original blockchain contract.

Figure 4: The technical principles of migration of smart contract code.

4.3 Migration of Smart Contract Status

For the contract status, it is necessary to traverse all

the status data in the contract through the original

blockchain contract interface and other methods, and

write the data into the corresponding contract in the

genesis block file of the new blockchain. When the

new blockchain is started, the contract status can be

written into the new blockchain.

5 CONCLUSIONS

A blockchain is a special database that stores

transaction information on a block's data structure,

while running smart contracts and keeping state

within them. For data migration in the blockchain,

there are usually several types of data: block and

transaction data, smart contract code, and smart

contract status data. Traditional databases can directly

Research Progress of Heterogeneous Blockchain Data Migration Technology

553

extract, translate, load data, and finally perform

consistency verification. However, for heterogeneous

blockchain, data migrantion inevitably involves data

reconstruction and modification, which may make the

blockchain lose the characteristics as an "invariant

historical database".

Heterogeneous blockchain data migration

technology ensures the integrity of historical data

existence proof, the consistency of smart contract

logic, and the compatibility of the interface. The

research on migration technology of transaction and

block content, smart contract logic and smart contract

code data realizes the permanent availability of

historical data. This research can break through the

technical bottleneck that the current heterogeneous

blockchain cannot guarantee the integrity of the

original data and business consistency, the loss of the

proof of the existence of data in the process of data

migration. To form an overall plan for heterogeneous

blockchain data migration, which can support the

technological upgrade of blockchain platforms in

different enterprises and industries, and promote the

healthy development of blockchain technology.

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