Open Integration Equipment Integration Server (openEI_server (EIS)) is a middle-ware server application designed to provide connectivity between multiple equipments and various host applications. Due to the limitation of SECS/GEM standards, only one host application is allowed to be directly connected to an equipment at any one time.

To enable multiple host applications to connect to a piece of equipment concurrently, EIS serves as a middle-ware which connects itself directly to equipments and allow multiple host applications to communicates with equipments via the server.

In addition, openEI_server (EIS) also serves as a message translator. It translates binary SECS/GEM messages from equipment to high-level .NET events and XML messages before sending those messages to receiving host applications. It also translates XML messages received from host application to SECS/GEM messages before sending those messages to the target equipment. This feature effectively shielded host applications from the need to understand SECS/GEM protocols and language.