# Special Equipment Safety Supervision System Architecture Based on Blockchain Technology
## 4 Blockchain System Architecture for Safety Supervision of Special Equipment
### System Design  
When we establish a safety supervision system of special equipment based on the Hyperledger Fabric blockchain, it means that the \"transaction\" in the blockchain will be regarded as the update of supervision information, which is completed by the smart contract (smart contracts in Hyperledger Fabric are written in chaincode), and each participant will be regarded as a \"peer\". As shown in Figure 3, there are many users of this system in the blockchain network, who can invoke the smart contract by mobile APP or computer programs to complete their work. It must be mentioned that Hyperledger Fabric provides us with the ability to create a \"channel\", which allows a group of users to establish a separate ledger of safety supervision work. This means that we can set up a \"channel\" for every enterprise using special equipment, and let the users who entered the supervision system with permission be divided into different \"channels\", so as to realize the independent supervision of every enterprise using special equipment. A channel has one, and only one, ledger; each peer in the channel maintains the same ledger, and they can copy this ledger, which is also the advantage of distributed ledger. According to the number of participants in each channel we set, there will only be 6-8 copies of each ledger. \begin{table}
\begin{tabular}{l l} \hline \hline
**Features of Hyperledger Fabric** & \
\begin{tabular}{l} **Corresponding Requirements and Technical Features of** \\ **Safety Supervision of Special Equipment** \\ \end{tabular} \\ \hline Permissioned and modular architecture &
\begin{tabular}{l} Authorization for participants in supervision work, integrating \\ more functions into the safety supervision system \\ \end{tabular} \\ \hline Querable data—supporting multiple query methods, and event hooks to integrate data into your preferred database or analytics engine. & Efficient accident responsibility tracing \\ \hline Lower latency of confirmation & More efficient supervision and data sharing \\ \hline Supporting rolling upgrades and asymmetric version & Expansibility, new requirements in the future \\ \hline Open smart contract model—flexibility to support various solution and & \\ data models (account model, UTKO model, structured data, & Supporting diversified supervision information records \\ unstructured data, etc.) & \\ \hline Data privacy—complete transaction isolation using “channels”, or share & Keeping data safe, supporting the independent supervision of \\ private data on a need-to-know basis using private data “collections” & each equipment and the classified supervision \\ \hline Multi-language smart contract support: Go, Java, Javascript & More suitable developers, lower development threshold \\ \hline Governance and versioning of smart contracts & Flexible and efficient supervision information records \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The suitability between Hyperledger Fabric and safety supervision system of special equipment. As can be seen in Figure 3, this is the workflow of performing ledger updates by smart contracts: At the beginning, the SDK-based application will submit the endorsement verification to the specific peer involved in the work (maybe the equipment users, inspection agencies, primary supervisors, or supervisory agencies in this project), and then the peer will return the result. After enough endorsements are collected, the SDK-based application broadcasts the update application to the orderer for ordering, packaging, and sending it to the peer, and then the update will be completed after the peer verifies the update information. In addition, it needs to be explained that the ordering service is used to provide an atomic broadcast ordering service for consumption by the peers.