Module health.hl7v26

ballerinax/health.hl7v26 Ballerina library


Module for HL7 v2.6 specification.

HL7 v2.6 Module

Module Overview

This Module holds the messages, segments and data types for the HL7 version 2.6.


To add the HL7 v2.6 dependency the project simply import the package as below,

import ballerinax/health.hl7v26

Sample: Simple HL7 Server implementation compatible for HL7 v2.6 which accept any message HL7 message available in this package. This server binds to port 3000

Tip: Use Hapi TestPanel or any HL7 v2.6 compatible client to invoke this server.

import ballerina/io;
import ballerina/tcp;
import ballerina/uuid;
import ballerinax/health.hl7v2;
import ballerinax/health.hl7v26;

service on new tcp:Listener(3000) {
    remote function onConnect(tcp:Caller caller) returns tcp:ConnectionService {
        io:println("Client connected to HL7 server: ", caller.remotePort.toString());
        return new HL7ServiceConnectionService();

service class HL7ServiceConnectionService {
    remote function onBytes(tcp:Caller caller, readonly & byte[] data) returns tcp:Error? {
        string|error fromBytes = string:fromBytes(data);
        if fromBytes is string {
            io:println("Received HL7 Message: ", fromBytes);

        // Parse the received message.
        hl7v2:Message|error parsedMsg = hl7v2:parse(data);
        if parsedMsg is error {
            return error(string `Error occurred while parsing the received message: ${parsedMsg.message()}`,
        io:println(string `Parsed HL7 message: ${parsedMsg.toJsonString()}`);

        // Extract Message header (MSH).
        hl7v26:MSH? msh = ();
        if parsedMsg is hl7v2:Message && parsedMsg.hasKey("msh") {
            anydata mshEntry = parsedMsg["msh"];
            hl7v26:MSH|error tempMSH = mshEntry.ensureType();
            if tempMSH is error {
                return error("Error occurred while casting MSH", tempMSH);
            msh = tempMSH;
        if msh is () {
            return error("Failed to extract MSH from HL7 message");

        // Create Acknowledgement message.
        hl7v26:ACK ack = {
            msh: {
                msh2: "^~\\&",
                msh3: {hd1: "TESTSERVER"},
                msh4: {hd1: "WSO2OH"},
                msh5: {hd1: msh.msh3.hd1},
                msh6: {hd1: msh.msh4.hd1},
                msh9: {"cm_msg1": hl7v26:ACK_MESSAGE_TYPE},
                msh10: uuid:createType1AsString().substring(0, 8),
                msh11: {pt1: "P"},
                msh12: {vid1: "2.6"}
            msa: {
                msa1: "AA",
                msa2: msh.msh10
        // Encode message to wire format.
        byte[]|hl7v2:HL7Error encodedMsg = hl7v2:encode(hl7v26:VERSION, ack);
        if encodedMsg is hl7v2:HL7Error {
            return error("Error occurred while encoding acknowledgement", encodedMsg);

        string|error resp = string:fromBytes(encodedMsg);
        if resp is string {
            io:println(string `Encoded HL7 ACK Response Message: ${resp}`);

        // Echoes back the data to the client from which the data is received.
        check caller->writeBytes(encodedMsg);

    remote function onError(tcp:Error err) {
        io:println(string `An error occurred while receiving HL7 message: ${err.message()}. Stack trace: `,

    remote function onClose() {
        io:println("Client left.");