## 3 Smart and Secure HIE Systems: SSHES
### Architecture of HIE Systems  
The structure and design of a Health Information Exchange (HIE) system encompass the framework enabling the secure transmission of health information among diverse healthcare entities (Figure 3). Indeed, HIE systems are pivotal for enhancing healthcare provision, coordination, and patient results by fostering smooth data sharing among  
Figure 1: Publication selection in terms of years.  
Figure 2: Publication selection in terms of publishers.  
different healthcare providers. The architecture of any HIE system typically consists of several key components [13; 14; 15; 16]:  
* Data Sources: they indicate entities responsible for generating and storing health-related data, such as EHRs, laboratory entities, radiology departments, pharmacies, and other healthcare applications. They may be centralized within a single healthcare organization or dispersed across multiple entities [13].
* Health Information Exchange Infrastructure: it constitutes the backbone of the HIE system, comprising essential hardware, software, and network components to facilitate data exchange. This infrastructure usually encompasses servers, databases, communication protocols, security measures, and interfaces designed for data integration and interoperability [13; 14].
* Master Patient Index (MPI): it identifies and correlates patient records across diverse healthcare entities. It also preserves a distinct identifier for each patient and connects their records from multiple origins to construct a unified perspective of their health data [15; 16].
* Data Integration and Transformation: it undertakes the task of gathering data from various origins, standardizing it into a uniform format (such as HL7 or FHIR) and converting it into a shared data model for seamless exchange between systems [13; 14; 16].
* Data Exchange Standards: HIE systems depend on recognized interoperability norms to guarantee smooth communication among various healthcare software. Commonly used standards encompass Health Level Seven (HL7) messaging standards, Consolidated Clinical Document Architecture (CCDA), Fast Healthcare Interoperability Resources (FHIR), and Clinical Document Architecture (CDA).
* Data Security and Privacy: because of their sensitivity, HIE systems utilize multiple security procedures including cryptography, access controls, authentication, and audit trails, to maintain data confidentiality, integrity, and availability [15; 16].
* Enterprise Master Patient Index (EMPI): in large HIE systems covering multiple regions or states, an Enterprise Master Patient Index (EMPI) might be employed to centralize patient records from various Master Patient Indexes (MPIs). The EMPI aids  
Figure 3: General architecture of HIE systems.  
in reconciling duplicate or conflicting patient records by managing a central index of distinct patient identifiers and associating them with their corresponding MPIs.
* Health Information Services: they include patient matching algorithms, record locator services, clinical decision support systems, analytics, and population health management tools [17; 18].
* Participant Directory: it acts as a centralized repository of information about healthcare organizations participating in the network. It includes their contact information, supported data types, available services, and technical specifications. This directory streamlines the process of discovering and incorporating new participants into the HIE network.
* Governance and Policy Framework: an effective governance structure is crucial for the smooth operation of an HIE system. This encompasses well-established policies and procedures regarding data sharing agreements, consent management, data stewardship, dispute resolution mechanisms, and adherence to legal and regulatory requirements [14; 16].