# Privacy-Aware Cloud Architecture for Collaborative Use of Patients' Health Information
## 2 Related Work
The authors draw attention to a critical problem that results from the incompatibility of data models, such as the use of proprietary terminology, data structures, data formats, and semantics by different software systems. Data must be shared between software systems, and frequently, challenging data conversions or transformations are necessary. Process modelling is also difficult due to the complexity of healthcare information systems and requirements, which accounts for the slow adoption of process modelling standards [46]. Enterprise Service Bus (ESB) [47] is another approach that serves as a platform for integrating different applications and services within an enterprise. EBS is an architectural pattern whereby a centralized software component performs integrations between applications. In a service-oriented architecture (SOA) [48], EBS implements a communication mechanism between software programs that interact with one another by acting as a central hub or mediator, enabling communication and information exchange between different systems and services. In [49], the authors conducted a study to understand and provide ongoing research topics, challenges, and future directions concerning ESB applications. While ESB is seen as a powerful approach for enterprise integration and data exchange, its adoption in the healthcare domain requires meeting difficult requirements related to accessibility in light of the fragmentation of patients' information in heterogeneous proprietary systems. Blockchain is another approach that is widely used in healthcare information systems due to its decentralization and security features [50]. The adoption of blockchain technology is becoming a widespread trend in distributed computing. Many researchers considered the use of it for sharing information across healthcare information systems [51]. In [52], the authors discuss the development and user experience of a personal health record (PHR) application that incorporates blockchain technology. By leveraging blockchain's decentralized and immutable nature, the application ensures secure storage and management of health-related information, granting users control over their data. The study highlights positive user feedback regarding the application's usability and effectiveness in managing health records. It also addresses challenges such as scalability and regulatory compliance. An example of a suggested blockchain-based application is found in [53]. The author proposed a distributed, smart, and secure healthcare system using blockchain and edge computing for sharing medical information across different institutions. The proposed system shares data by separating medical data processing, access control, and data sharing into local and blockchain networks. The work also presents a data-sharing security algorithm based on the value of the shared data. The proposed system has significant drawbacks related to quality of service and information privacy. In terms of quality of service, it is difficult to guarantee consistent service quality because various validation times depend on the security level, while the move of data through edge nodes in the local network may lead to centralization and privacy concerns especially because data may not be encrypted. Another blockchain-based work for sharing healthcare information is presented in [54]. The authors presented an attribute-based encryption system for authorization and dynamic authentication of medical on-demand services in remote medical systems. Blockchain technology in the system was exploited along with distributed database technologies to protect the integrity of information. However, the approach suffered from limitations related to centralization and security. The authors in [55] conducted a review of blockchain-based secure sharing of healthcare data. The review included an evaluation of the development of blockchain in healthcare from various perspectives. It also analyzed the approaches to blockchain in different application scenarios.