Κατανεμημένο πληροφοριακό σύστημα υγείας σε περιβάλλον internet

Abstract

In this thesis we designed and implemented a distributed architectural model of Primary Healthcare Information Systems (PHeCISs) for regional healthcare environments. Our model handles patient case management as a distributed workflow, which includes distributed access and updating of Electronic Healthcare Records, patient assessment and care planning. The distribution of information and processes is handled by introducing a Roaming Electronic Healthcare Record and by using local caching and incremental updates of a global index. A Roaming Manager (RM) entity is responsible for the location of information and the update procedures in a region. We discuss efficiency, scalability and security issues and we present a "proof of concept" implementation based on middleware (SOAP/XML, CORBA/IIOP) and web-based technologies. Finally, we present two management alternatives within the framework of integrated system and application management. The first is based on the Simple Network Management Protocol (SNMP) and the second on the Java Management extensions (JMX) architecture. Although SNMP is a widely used network management protocol, its applicability to application and host resources management is rather limited, while JMX is an open, complete, extensible and scalable architecture. JMX enables the development of thin modules and provides a wide scope of APIs for application managers, Web managers, browsers, SNMP agents etc.; thus, it better fits our requirements and Java based distributed architecture. A prototype was implemented to evaluate the performance of the proposed distributed architecture. We adopted a three-tier approach for both system entities (PHeCIS & RM): (1) database tier, (2) business logic tier QavaBeans and Java Servlets) and (3) presentation tier (JSPs & HTML static pages for PHeCISs; the RM interacts with a human administrator only). The implementation was based on the Java environment, which provides platform independence and back-end database portability, while the distributed interaction protocol was based on the Simple Object Access Protocol (SOAP), an open standard that implements interoperability between heterogeneous applications on multiple platforms via Internet type Wide Area Networks (WANs). Security issues were resolved through an "Open PKI — Public Key Infrastructure". The evaluation of the prototype in various scenarios provided very encouraging results: (1) storage requirements are minimal compared to full mirroring of data, (2) the system redundancy provides fault tolerance (data is stored at least in two places — the Roaming Manager and in one or more PHeCIS's), (3) the proposed interaction protocol ensures that the Electronic Healthcare Record follows the patient in any Health Center that he visits in a transparent and efficient fashion, and (4) the adoption of SOAP/XML perfectly fits a WAN platform, without requiring complicated firewall/filter modifications (when compared to other technologies, such as CORBA/IIOP and Java RMI).