# A Hyperledger Fabric-Based System Framework for Healthcare Data Management
## 5 Discussion
The proposed solution does not need to deploy a separate consensus mechanism, instead it uses the pluggable Raft consensus provided by Hyperledger Fabric. Decentralized applications that are based on blockchain technology need to process, store, or update the same ledger at each node, which consumes a large amount of space. The healthcare data storage cycle can be as long as several decades so that the demand for storage space is even higher. The proposed system introduces cloud storage and stores the hash value of the original data in the blockchain, eliminating the need for nodes to have massive storage space. Centralized cloud computing uses traditional and mature data security strategies to ensure that healthcare data can be stored stably and reliably. The blockchain network ensures that data in the system can be traced and cannot be tampered with. In the patient-driven access control model, all requests for access to healthcare data will be reviewed by the patient and a decision will be made as to whether to authorize access. Although this type of model can protect patient privacy to the utmost extent and prevent unauthorized access requests, the patient does not have enough professional knowledge to determine which data or information should be authorized to improve healthcare service quality; this will cause many negative effects. First, doctors and patients may not be able to reach a consensus on whether to authorize access to certain information, leading to increasing the cost of communication between doctors and patients. Secondly, reviewing and authorizing information one by one will increase data management costs and reduce efficiency and patients may also avoid trouble or be misled to allow all access requests. Moreover, research institutions or government health departments also need to use healthcare data to assist research or policy formulation and patients should not have the right to refuse such reasonable high-privilege access requests. Therefore, the access control model that is based on human decision-making has many shortcomings. It is hoped that access control strategies can be implemented through automated procedures, thereby improving efficiency and reducing costs. The hierarchical access control smart contract that was designed in this paper assigns a security level to each record when information is uploaded to the blockchain network and is linked with the original data through the hash algorithm. Different access requests can be automatically processed, and the system will show them the corresponding security level information according to the audit results. Automated hierarchical access control contracts can reduce the communication costs between patients and information users, avoid false authorizations, and improve the efficiency of access control for all parties. The feasibility of the proposed healthcare data management solution is embodied not only in the ability to upgrade and reform through existing data sharing schemes but also to benefit the participants. The smart contract for hierarchical access control can automatically grant corresponding access permissions according to the purpose of access to avoid disputes about privacy issues for all participants. For patients, the system can save healthcare records to their client and provide patients with healthcare data usage logs to monitor the purpose of data access. For healthcare service providers, the system has not changed the habit of recording and archiving healthcare services, as well as providing a more convenient and secure way to access and share data with alternative medical professionals. The usage of healthcare data is saved through the blockchain network, enabling direct supervision of government health departments. Since the proposed solution is based on the Hyperledger Fabric, more data interfaces can be introduced easily to connect more organizations such as research institutions, insurance, pharmaceutical companies, and international medical tourism.