Most of the hospitals, medical centers and outpatient clinics in Jordan have made major investments in transferring their manual health records to electronic health records (EHRs). However, heterogeneity and lack of appropriated middleware made these EHRs inaccessible on the national level despite the availability of advanced telecom infrastructure in the country. This paper presents a new central middleware architecture that enables seamless and secure exchange of data and services between the local EHRs and a remote national EHR database system. The proposed middleware tackles a standing interoperability problem between these distributed healthcare entities and thus enables the caregivers to access EHRs of their patients on the national level without restrictions of time or geographical location. This is achieved by developing a structured form of interoperability between distributed clients and servers and the central EHR database server that simplifies the integration process and shifts the complexity towards the central middleware system. The developed pilot middleware prototype has demonstrated seamless and secure exchange of data and services.