Load balancing refers to distributing incoming HTTP requests across Web servers in a server farm, to avoid overloading any one server. It is because load balancing distributes the requests based on the actual load at each server.
EMS Web Site
EMS Web site handles the user interface and client side scripting. It also retrieves the reports from Reporting service and present to user.
EMR Services includes the business object layer, application utilities, Windows Communication Foundation (WCF) service contracts, Services for WCF and a Service Tester that is used to do simple test for service connections.
EMR Reports uses FastReport.NET for the Reporting services.
Rabbitmq or Activemq is message broker. It is intermediary program that translates a message from the formal messaging protocol of the sender to the formal messaging protocol of the receiver in a telecommunication network where programs communicate by exchanging formally-defined messages
EMR Database stores EMR projects and transaction data.