Understanding the HL7 Protocol

In this section:

Health Level Seven (HL7) is a standard for information exchange between medical applications. It is the seventh OSI layer protocol for exchanging information in healthcare systems. HL7 defines a protocol for data exchange. It also defines the format and the content of the messages that applications must use when exchanging data with one another in various circumstances. The following descriptions provide an outline for the protocol.


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Event Driven Protocol

Real world events, such as the admission of a patient, cause messages to flow between applications. In other words, an application that encounters a real world event sends a message to other applications that need to be aware of this event.


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Application to Application Protocol

It defines a communication between two independent applications, rather than between closely coupled, client-server type applications. The scope of interest for HL7 is the message exchange between the applications, rather than the specific role of each application in the health care delivery process.


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OSI Level 7 Protocol

The scope of HL7 is the format and content of the data exchanged between the applications, not how it is passed between computers or networks. HL7 does not specify how messages will be delivered between the applications. Usually a TCP/IP connection or FTP file transfer is used to deliver a message. However, within local area networks, the standard is the Lower Layer Protocol.


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Exchange Protocol

HL7 specifies the way data exchange between applications will be accomplished. It does not specify how applications store or process this data. In an application, it is recommended that a database structure coincides with HL7 message definitions. However, this is not mandatory.


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Standard Protocol

When a proprietary, non-standard link between two systems is made, a message exchange that satisfies your requirements and fits into the data structure of your application can be created. However, the efforts invested in this link are useless when considering a connection to other third-party systems. When you are using HL7, your initial development effort can be reused.

For more information on the HL7 standard, please visit the following website:

http://www.hl7.org


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