HL7 Versions
To make it easier to send and receive health-care information, the HL7 organization has defined a standard that specifies what types of HL7 messages can be sent, what segments can be included in these messages, and what fields can be included in their segments. The HL7 standard is constantly evolving. To date, the HL7 committee […]
HL7 Version 2.X
Version 2 of the HL7 standard is the version that is currently in common use. It has been designed to always be backward compatible. For example, version 2.6 of the standard is compatible with version 2.5. This ensures that existing applications that use the standard do not have to be constantly updated to match the […]
HL7 Version 3.0
Since 1997, the HL7 organization has been developing version 3.0 of the protocol. Unlike 2.X versions, HL7 3.0 is based largely on a single formal model called the Reference Information Model, or RIM. The goal of RIM is to reduce the implementation costs of HL7-enabled solutions and further standardize the HL7 communication specifications between healthcare […]
The ACKnowledgment Protocol
An important part of the HL7 standard is the ACKnowledgment protocol. Every time an application accepts a message and consumes the message data, it is expected to send an ACKnowledgment message back to the sending application. The sending application is expected to keep on sending a message until it has received an ACK message. If […]
HL7 Protocol Characteristics
HL7 is a structured protocol that is used as a means of communicating between healthcare applications. The following descriptions provide an outline that define the characteristics of the HL7 protocol: Event-Driven 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 […]
Common HL7 Transports
This section describes the most common HL7 transport method used to send HL7 messages, called the Lower Layer Protocol (LLP). A less common HL7 transport called the Hybrid Lower Layer Protocol (HLLP) is also briefly discussed. Although HL7 messages are sent via a variety of TCP/IP transports, including FTP, SOAP and SMTP, LLP is the […]
TCP/IP Basics
In this section, you will learn about the basics of TCP/IP based communication. This section will also discuss the roles of the client and server when implementing an HL7 interface, as well as the limits of TCP/IP. Client or Server When implementing an HL7 interface, your interface will either be acting as a Client or […]
Testing TCP/IP LLP Connections
It can often be useful to test LLP implementations using a low-level tool to view the raw data being transmitted by an interface. An example of such a tool is MSOCS (shown below).
Hybrid Lower Layer Protocol (HLLP)
The Hybrid Lower Layer Protocol (HLLP) is a variation of the more widely used Lower Layer Protocol. Like LLP, HLLP uses TCP/IP as its transport but incorporates error detection and verification via the use of checksums at the end of messages. The checksums are used to verify that no data was corrupted. Checksums are typically […]
