I’ve had many years of experience working with the NextGen EHR/PM. While I was working with Centra Care, I had the pleasure of writing many PHP applications which supplemented the main electronic health records system. We called them bolt-on application. I’m familiar with the Nextgen database and how to integrate external applications with NextGen; HL7 and the FHIR DSTU2 Standards.
PHP Cerner FHIR DSTU2 API Classes for consuming data from a FHIR DSTU2 server using PHP7 with Symfony 4: