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The hl7 component is used for working with the HL7 MLLP protocol and the HL7 model using the HAPI library.

This component supports the following:

  • HL7 MLLP codec for Mina.

  • Agnostic data format using either plain String objects or HAPI HL7 model objects.

  • Type Converter from/to HAPI and String.

  • HL7 DataFormat using HAPI library.

  • Even more easy-of-use as it is integrated well with the camel-mina component.

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-hl7</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

HL7 is often used with the HL7 MLLP protocol that is a text based TCP socket based protocol. This component ships with a Mina Codec that conforms to the MLLP protocol so you can easily expose a HL7 listener that accepts HL7 requests over the TCP transport.

To expose a HL7 listener service we reuse the existing camel-mina component where we just use the HL7MLLPCodec as codec.

The HL7 MLLP codec has the following options:

Name Default Value Description
startByte 0x0b The start byte spanning the HL7 payload. Is the HL7 default value of 0x0b (11 decimal).
endByte1 0x1c The first end byte spanning the HL7 payload. Is the HL7 default value of 0x1c (28 decimal).
endByte2 0x0d The 2nd end byte spanning the HL7 payload. Is the HL7 default value of 0x0d (13 decimal).
charset JVM Default The encoding (is a charset name) to use for the codec. If not provided, Fuse Mediation Router will use the JVM default Charset.
convertLFtoCR true Will convert \n to \r (0x0d, 13 decimal) as HL7 usually uses \r as segment terminators. The HAPI library requires the use of \r.
validate true Fuse Mediation Router 2.0: Whether HAPI Parser should validate or not.

In our Spring XML file, we configure an endpoint to listen for HL7 requests using TCP:

        <endpoint id="hl7listener" uri="mina:tcp://localhost:8888?sync=true&codec=#hl7codec"/>

Notice we configure it to use camel-mina with TCP on the localhost on port 8888. We use sync=true to indicate that this listener is synchronous and therefore will return a HL7 response to the caller. Then we set up mina to use our HL7 codec with codec=#hl7codec. Notice that hl7codec is just a Spring bean ID, so we could have named it mygreatcodecforhl7 or whatever. The codec can also be set up in the Spring XML file:

    <bean id="hl7codec" class="org.apache.camel.component.hl7.HL7MLLPCodec">
        <property name="charset" value="iso-8859-1"/>
    </bean>

And here we configure the charset encoding to use, and iso-8859-1 is commonly used.

The endpoint hl7listener can then be used in a route as a consumer, as this java DSL example illustrates:

    from("hl7listener").to("patientLookupService");

This is a very simple route that will listen for HL7 and route it to a service named patientLookupService that is also a Spring bean ID we have configured in the Spring XML as:

    <bean id="patientLookupService" class="com.mycompany.healtcare.service.PatientLookupService"/>

And another powerful feature of Fuse Mediation Router is that we can have our busines logic in POJO classes that are not at all tied to Fuse Mediation Router as shown here:

public class PatientLookupService {
    public Message lookupPatient(Message input) throws HL7Exception {
        QRD qrd = (QRD)input.get("QRD");
        String patientId = qrd.getWhoSubjectFilter(0).getIDNumber().getValue();

        // find patient data based on the patient id and create a HL7 model object with the response
        Message response = ... create and set response data
        return response
    }

Notice that this class is just using imports from the HAPI library and none from Fuse Mediation Router.

Key MSH field Example
hl7.msh.sendingApplication MSH-3 MYSERVER
hl7.msh.sendingFacility MSH-4 MYSERVERAPP
hl7.msh.receivingApplication MSH-5 MYCLIENT
hl7.msh.receivingFacility MSH-6 MYCLIENTAPP
hl7.msh.timestamp MSH-7 20071231235900
hl7.msh.security MSH-8 null
hl7.msh.messageType MSH-9-1 ADT
hl7.msh.triggerEvent MSH-9-2 A01
hl7.msh.messageControl MSH-10 1234
hl7.msh.processingId MSH-11 P
hl7.msh.versionId MSH-12 2.4

Key MSH field Example
CamelHL7SendingApplication MSH-3 MYSERVER
CamelHL7SendingFacility MSH-4 MYSERVERAPP
CamelHL7ReceivingApplication MSH-5 MYCLIENT
CamelHL7ReceivingFacility MSH-6 MYCLIENTAPP
CamelHL7Timestamp MSH-7 20071231235900
CamelHL7Security MSH-8 null
CamelHL7MessageType MSH-9-1 ADT
CamelHL7TriggerEvent MSH-9-2 A01
CamelHL7MessageControl MSH-10 1234
CamelHL7ProcessingId MSH-11 P
CamelHL7VersionId MSH-12 2.4

All headers are String types. If a header value is missing, its value is null.

The HL7 Data Format supports the following options:

Option Default Description
validate true Camel 2.0: Whether the HAPI Parser should validate.

To use HL7 in your camel routes you need to add a dependency on camel-hl7, which implements this data format.

If you use Maven, you could just add the following to your pom.xml, substituting the version number for the latest & greatest release.

<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-hl7</artifactId>
  <version>2.2.0</version>
</dependency>

Since HAPI 0.6, the library has been split into a base library and several structures libraries, one for each HL7v2 message version:

By default camel-hl7 only references the HAPI base library. Applications are responsible for including structures libraries themselves. For example, if a application works with HL7v2 message versions 2.4 and 2.5 then the following dependencies must be added:

<dependency>
    <groupId>ca.uhn.hapi</groupId>
    <artifactId>hapi-structures-v24</artifactId>
    <version>1.0</version>
</dependency>
<dependency>
    <groupId>ca.uhn.hapi</groupId>
    <artifactId>hapi-structures-v25</artifactId>
    <version>1.0</version>
</dependency>

An OSGi bundle containing the base library, all structures libraries and required dependencies (on the bundle classpath) can be downloaded from the HAPI Maven repository as well.

<dependency>
    <groupId>ca.uhn.hapi</groupId>
    <artifactId>hapi-osgi-base</artifactId>
    <version>1.0.1</version>
</dependency>

In the following example we send a HL7 request to a HL7 listener and retrieves a response. We use plain String types in this example:

String line1 = "MSH|^~\\&|MYSENDER|MYRECEIVER|MYAPPLICATION||200612211200||QRY^A19|1234|P|2.4";
String line2 = "QRD|200612211200|R|I|GetPatient|||1^RD|0101701234|DEM||";

StringBuilder in = new StringBuilder();
in.append(line1);
in.append("\n");
in.append(line2);

String out = (String)template.requestBody("mina:tcp://127.0.0.1:8888?sync=true&codec=#hl7codec", in.toString());

In the next sample, we want to route HL7 requests from our HL7 listener to our business logic. We have our business logic in a plain POJO that we have registered in the registry as hl7service = for instance using Spring and letting the bean id = hl7service.

Our business logic is a plain POJO only using the HAPI library so we have these operations defined:

public class MyHL7BusinessLogic {

    // This is a plain POJO that has NO imports whatsoever on Fuse Mediation Router.
    // its a plain POJO only importing the HAPI library so we can much easier work with the HL7 format.

    public Message handleA19(Message msg) throws Exception {
        // here you can have your business logic for A19 messages
        assertTrue(msg instanceof QRY_A19);
        // just return the same dummy response
        return createADR19Message();
    }

    public Message handleA01(Message msg) throws Exception {
        // here you can have your business logic for A01 messages
        assertTrue(msg instanceof ADT_A01);
        // just return the same dummy response
        return createADT01Message();
    }
}

Then we set up the Fuse Mediation Router routes using the RouteBuilder as follows:

DataFormat hl7 = new HL7DataFormat();
// we setup or HL7 listener on port 8888 (using the hl7codec) and in sync mode so we can return a response
from("mina:tcp://127.0.0.1:8888?sync=true&codec=#hl7codec")
    // we use the HL7 data format to unmarshal from HL7 stream to the HAPI Message model
    // this ensures that the camel message has been enriched with hl7 specific headers to
    // make the routing much easier (see below)
    .unmarshal(hl7)
    // using choice as the content base router
    .choice()
        // where we choose that A19 queries invoke the handleA19 method on our hl7service bean
        .when(header("CamelHL7TriggerEvent").isEqualTo("A19"))
            .beanRef("hl7service", "handleA19")
            .to("mock:a19")
        // and A01 should invoke the handleA01 method on our hl7service bean
        .when(header("CamelHL7TriggerEvent").isEqualTo("A01")).to("mock:a01")
            .beanRef("hl7service", "handleA01")
            .to("mock:a19")
        // other types should go to mock:unknown
        .otherwise()
            .to("mock:unknown")
    // end choice block
    .end()
    // marhsal response back
    .marshal(hl7);

Notice that we use the HL7 DataFormat to enrich our Camel Message with the MSH fields preconfigued on the Camel Message. This lets us much more easily define our routes using the fluent builders. If we do not use the HL7 DataFormat, then we do not gains these headers and we must resort to a different technique for computing the MSH trigger event (= what kind of HL7 message it is). This is a big advantage of the HL7 DataFormat over the plain HL7 type converters.

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