Health information technology (HIT) systems including electronic health records (EHRs) have a market saturation nearing 92% at individual institutions but are still unsuited for cross-institutional collaboration of stakeholders (e.g., medical providers such as physicians, hospitals, clinics, labs, etc.) in support of health information exchange (HIE) of different HIT systems in geographically separate locations. In the computer science field, software architectures such as service-oriented architecture, grid computing, publish/subscribe paradigm, and data warehousing are well-established approaches for interoperation. However, the application of these software architectures to support HIE has not been significantly explored. To address this issue, this paper proposes an architectural solution for HIE that leverages established software architectural styles in conjunction with the emergent HL7 standard Fast Healthcare Interoperability Resources (FHIR). FHIR models healthcare data with XML or JSON schemas using a set of 93 resources to track a patient's clinical findings, problems, allergies, adverse events, history, suggested physician orders, care planning, etc. For each resource, a FHIR CRUD RESTful Application Program Interface (API) is defined to share data in a common format for each of the HITs that can then be easily accessible by mobile applications. This paper details an architectural solution for HIE using software architectural styles in conjunction with FHIR to allow HIT systems of stakeholders to be integrated to facilitate collaboration among medical providers. To demonstrate the feasibility and utility of HHIEA, a realistic regional healthcare scenario is introduced that illustrates the interactions of stakeholders across an integrated collection of HIT systems.