HL7 v2 Reference Guide
HL7 v2 is the backbone of clinical data exchange — ADT events, lab orders, results, documents, and pharmacy messages that move between HIS, EHR, LIS, RIS, and billing systems across every major hospital.
HL7 Message Guides
112 guides covering common message types and integration patterns.
HL7 Segments
173 segments — the named field groupings that make up every HL7 v2 message.
HL7 Data Types
69 data types — the field-level building blocks used across every segment.
HL7 Code Tables
79 code tables — the standardized value sets referenced by HL7 v2 fields.
Transport Methods
How HL7 v2 messages move between systems — MLLP, HTTPS, and the rest.
HL7 Transport: Minimal Lower Layer Protocol
MLLP is the de-facto standard for HL7 v2 message transport, using TCP-based persistent connections with byte-framing.
Read lesson →HL7 Transport: Raw TCP/IP
Unframed TCP/IP transport for HL7 messages without MLLP framing; requires application-level message boundary handling.
Read lesson →HL7 Transport: SFTP Batch Files
Asynchronous batch HL7 message transport via SSH File Transfer Protocol with file-based polling and atomic write patterns.
Read lesson →HL7 Transport: Shared Folder / File-Drop
Legacy file-sharing transport for exchanging HL7 v2 messages via SMB/CIFS or NFS shares with polling and batch envelope segments.
Read lesson →HL7 Transport: HL7 over HTTPS/REST
HTTP POST and REST APIs for transporting HL7 v2 and FHIR messages using TLS-secured endpoints.
Read lesson →HL7 Transport: SOAP Web Services
SOAP envelopes carrying HL7 v2 messages over HTTP/HTTPS with WSDL service definitions and WS-Security.
Read lesson →