A hospital needs a number of heterogeneous software applications to efficiently and accurately manage daily functions. A dedicated application system is available to cater to the needs of individual functional entity, such as Patient Registration, Billing, Nursing and Bed Management, Order Management, Pharmacy, Laboratory, and so on. These systems are provided by different vendors and are typically built using different technologies. HL7 plays the vital role of providing mechanism for interconnecting these disjoint systems. Although, each individual application entity has the capability of exchanging information using HL7 messages, they often maintain the same information in different forms and use different codes to represent common values. This calls for use of an integration engine that has HL7 capabilities and also provides support for transforming and mapping information being exchanged as per the agreement between two independent application systems.

The following diagram illustrates a typical integration scenario. Data is exchanged over different interfaces to ensure a connected and functional application system environment.

Different configurations employ different modes of communication for information exchange between heterogeneous systems internally and externally within an organization. Two widely used modes are:

• MLLP (Minimal Lower Layer Protocol) mode. For near real-time patient data exchange (billing, pharmacy, laboratory, and so on).
• Batch mode. For daily and weekly processing and backup of patient data (laboratory orders and results communicated daily).

Based on the communication workflow in effect, listener and preparser used for creating the Inlet are configured. The following combinations are recommended for the two communication modes discussed in the diagram above.

• Live Data Exchange

  HL7 MLLP listener is capable of data exchange using MLLP protocol and parsing the received HL7 messages before passing them on for further processing. HL7 MLLP listener also provides for generation of ACK/NACK acknowledgement based on the validation and verification of the received HL7 message.

• Batch Data Exchange

  File listener can be used to read the HL7 messages from the batches stored in files. These messages are then parsed and converted into XML format using a preparser configured for HL7 messages. If acknowledgement needs to be generated for these messages, then HL7 acknowledgement services should be used in the route.