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HL7 Component

The hl7 HL7 component is used for working with the HL7 MLLP protocol and HL7 v2 messages using the HAPI library.

This component supports the following:

• HL7 MLLP codec for MinaAgnostic
• data format using either plain String objects or HAPI HL7 model objects.HL7 MLLP codec for Netty4 from Camel 2.15 onwards
• Type Converter from/to HAPI and String
• HL7 DataFormat using the HAPI library
• Even more ease-of-use as it's integrated well with the camel-
mina (Camel 2.11: camel-
• mina2
)
• component.

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

...

...

HL7 MLLP protocol

HL7 is often used with the HL7 MLLP protocol that , which is a text based TCP socket based protocol. This component ships with a Mina and Netty4 Codec that conforms to the MLLP protocol so you can easily expose a an HL7 listener that accepts accepting HL7 requests over the TCP transport layer. To expose a HL7 listener service we reuse the existing mina/mina2 component where we just use the HL7MLLPCodec as codec.

The HL7 MLLP codec has the following options:

{div:class=confluenceTableSmall}
|| Name || Default Value || Description ||
| {{startByte}} | {{0x0b}} | The start byte spanning the HL7 payload. |
| {{endByte1}} | {{0x1c}} | The first end byte spanning the HL7 payload.|
| {{endByte2}} | {{0x0d}} | The 2nd end byte spanning the HL7 payload. |
| {{charset}} | JVM Default | The encoding (is a [charset name|http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html]) to use for the codec. If not provided, Camel will use the [JVM default Charset|http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html#defaultCharset()]. |
| {{convertLFtoCR}} | {{true}} (*Camel 2.11*:{{false}}) | Will convert {{\n}} to {{\r}} ({{0x0d}}, 13 decimal) as HL7 stipulates {{\r}} as segment terminators. The HAPI library requires the use of {{\r}}. |
| {{validate}} | {{true}} | Whether HAPI Parser should validate or not. |
| {{parser}} | {{ca.uhn.hl7v2.parser.PipeParser}} | *Camel 2.11:* To use a custom parser. Must be of type {{ca.uhn.hl7v2.parser.Parser}}. |
{div}

Exposing a HL7 listener

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&amp;codec=#hl7codec"/>
        <!-- Camel 2.11: uri="mina2:tcp... -->

Notice that we use TCP on 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 setup 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 is also 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>

, the camel-mina2 or camel-netty4 component is used with the HL7MLLPCodec (mina2) or HL7MLLPNettyDecoder/HL7MLLPNettyEncoder (Netty4).

HL7 MLLP codec can be configured as follows:

...

Exposing an HL7 listener using Mina

In the Spring XML file, we configure a mina2 endpoint to listen for HL7 requests using TCP on port 8888:

...

sync=true indicates that this listener is synchronous and therefore will return a HL7 response to the caller. The HL7 codec is setup with codec=#hl7codec. Note that hl7codec is just a Spring bean ID, so it could be named mygreatcodecforhl7 or whatever. The codec is also set up in the Spring XML file:

...

The endpoint hl7MinaLlistener can then be used in a route as a consumer, as this Java DSL example illustrates:

...

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

...

The business logic can be implemented in POJO classes that do not depend on Camel, as shown here:

...

Exposing an HL7 listener using Netty (available from Camel 2.15 onwards)

In the Spring XML file, we configure a netty4 endpoint to listen for HL7 requests using TCP on port 8888:

...

sync=true indicates that this listener is synchronous and therefore will return a HL7 response to the caller. The HL7 codec is setup with encoder=#hl7encoder and decoder=#hl7decoder. Note that hl7encoder and hl7decoder are just bean IDs, so they could be named differently. The beans can be set in the Spring XML file:

...

The endpoint hl7NettyListener can then be used in a route as a consumer, as this Java DSL example illustrates:

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HL7 Model using java.lang.String or byte[]

The HL7 MLLP codec uses plain String as its data format. Camel uses its Type Converter to convert to/from strings to the HAPI HL7 model objects, but you can use the plain String objects if you prefer, for instance if you wish to parse the data yourself.

As of Camel 2.14.1 you can also let both the Mina and Netty codecs use a plain byte[] as its data format by setting the produceString property to false. The Type Converter is also capable of converting the byte[] to/from HAPI HL7 model objects.

HL7v2 Model using HAPI

The HL7v2 model uses Java objects from the HAPI library. Using this library, you can encode

Above we also configure the charset encoding to use (iso-8859-1).

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.healthcare.service.PatientLookupService"/>

Another powerful feature of Camel is that we can have our business logic in POJO classes that is not tied to Camel as shown here:

...

import ca.uhn.hl7v2.HL7Exception;
import ca.uhn.hl7v2.model.Message;
import ca.uhn.hl7v2.model.v24.segment.QRD;

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 uses just imports from the HAPI library and not from Camel.

HL7 Model using java.lang.String

The HL7MLLP codec uses plain String as its data format. Camel uses its Type Converter to convert to/from strings to the HAPI HL7 model objects. However, you can use plain String objects if you prefer, for instance if you wish to parse the data yourself.

See samples for such an example.

HL7v2 Model using HAPI

The HL7v2 model uses Java objects from the HAPI library. Using this library, we can encode and decode from the EDI format (ER7) that is mostly used with HL7v2. With this model you can code with Java objects instead of the EDI based HL7 format that can be hard for humans to read and understand.

The sample below is a The sample below is a request to lookup a patient with the patient ID 0101701234.

...

Using the HL7 model we you can work with the data as a ca.uhn.hl7v2.model.Message object.
To retrieve the patient ID in the message above, you can do this in Java code:

...

, e.g. to retrieve a patient ID:

...

This is powerful when combined with the HL7 listener, because you don't have to work with byte[], String or any other simple object formats. You can just use the HAPI HL7v2 model objects. If you know the message type in advance, you can be more type-safe:

...

HL7 DataFormat

Message Headers

The unmarshal operation adds these fields from the MSH segment as headers on the Camel message:

...

All headers except CamelHL7Context are String types. If a header value is missing, its value is null.

Options

The HL7 Data Format supports the following options:

...

Dependencies

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

The HAPI library is split into a base library and several structure libraries, one for each HL7v2 message version:

• v2.1 structures library
• v2.2 structures library
• v2.3 structures library
• v2.3.1 structures library
• v2.4 structures library
• v2.5 structures library
• v2.5.1 structures library
• v2.6 structures library

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

...

Alternatively, an OSGi bundle containing the base library, all structures libraries and required dependencies (on the bundle classpath) can be downloaded from the central Maven repository.

...

Terser language

HAPI provides a Terser class that provides access to fields using a commonly used terse location specification syntax. The Terser language allows to use this syntax to extract values from messages and to use them as expressions and predicates for filtering, content-based routing etc.

Sample:

...

Camel has built-in type converters, so when this operation is invoked:

...

Message msg = exchange.getIn().getBody(Message.class);

Camel will convert the received HL7 data from String to Message. This is powerful when combined with the HL7 listener, then you as the end-user don't have to work with byte[], String or any other simple object formats. You can just use the HAPI HL7v2 model objects.

...

Message Headers

The unmarshal operation adds these MSH fields as headers on the Camel message:

{div:class=confluenceTableSmall}
|| 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}} |
{div}

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

Options

The HL7 Data Format supports the following options:

{div:class=confluenceTableSmall}
|| Option || Default || Description ||
| {{validate}} | true | Whether the HAPI Parser should validate using the default validation rules. *Camel 2.11:* better use the {{parser}} option and initialize the parser with the desired HAPI {{ValidationContext}} |
| {{parser}} | {{ca.uhn.hl7v2.parser.GenericParser}} | *Camel 2.11:* To use a custom parser. Must be of type {{ca.uhn.hl7v2.parser.Parser}}. Note that {{GenericParser}} also allows to parse XML-encoded HL7v2 messages. |

{div}

Dependencies

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

The HAPI library since Version 0.6 has been split into a base library and several structure libraries, one for each HL7v2 message version:

• v2.1 structures library
• v2.2 structures library
• v2.3 structures library
• v2.3.1 structures library
• v2.4 structures library
• v2.5 structures library
• v2.5.1 structures library
• v2.6 structures library

By default camel-hl7 only references the HAPI base library. Applications are responsible for including structure 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>1.2</version>
    <!-- use the same version as your hapi-base version -->
</dependency>
<dependency>
    <groupId>ca.uhn.hapi</groupId>
    <artifactId>hapi-structures-v25</artifactId>
    <version>1.2</version>
    <!-- use the same version as your hapi-base version -->
</dependency>

Alternatively, an OSGi bundle containing the base library, all structures libraries and required dependencies (on the bundle classpath) can be downloaded from the central Maven repository.

...

<dependency>
    <groupId>ca.uhn.hapi</groupId>
    <artifactId>hapi-osgi-base</artifactId>
    <version>1.2</version>
</dependency>

Terser language (Camel 2.11)

HAPI provides a Terser class that provides access to fields using a commonly used terse location specification syntax. The Terser language allows to use this syntax to extract values from messages and to use them as expressions and predicates for filtering, content-based routing etc.

Sample:

...

import static org.apache.camel.component.hl7.HL7.terser;
...

   // extract patient ID from field QRD-8 in the QRY_A19 message above and put into message header
   from("direct:test1")
      .setHeader("PATIENT_ID",terser("QRD-8(0)-1"))
      .to("mock:test1");
   // continue processing if extracted field equals a message header
   from("direct:test2")
      .filter(terser("QRD-8(0)-1")
      .isEqualTo(header("PATIENT_ID"))
      .to("mock:test2");

HL7 Validation predicate (Camel 2.11)

Often it is preferable to parse a HL7v2 message and validate it against a HAPI ValidationContext in a separate step afterwards.

Sample:

...

HL7 Acknowledgement expression (Camel 2.11)

A common task in HL7v2 processing is to generate an acknowledgement message as response to an incoming HL7v2 message, e.g. based on a validation result. The ack expression lets us accomplish this very elegantly:

...

HL7 Validation predicate

Often it is preferable to first parse a HL7v2 message and in a separate step validate it against a HAPI ValidationContext.

Sample:

...

More Samples

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:

{snippet:id=e2|lang=java|url=camel/trunk/components/camel-hl7/src/test/java/org/apache/camel/component/hl7/HL7MLLPCodecTest.java}

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:

{snippet:id=e2|lang=java|url=camel/trunk/components/camel-hl7/src/test/java/org/apache/camel/component/hl7/HL7RouteTest.java}

Then we set up the Camel routes using the RouteBuilder as follows:

{snippet:id=e1|lang=java|url=camel/trunk/components/camel-hl7/src/test/java/org/apache/camel/component/hl7/HL7RouteTest.java}

Notice that we use the HL7 DataFormat to enrich our Camel Message with the MSH fields preconfigured 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.

Sample using plain String objects

In this sample we use plain String objects as the data format, that we send, process and receive. As the sample is part of a unit test, there is some code for assertions, but you should be able to understand what happens. First we send the plain string, Hello World, to the HL7MLLPCodec and receive the response as a plain string, Bye World.

...

HL7 Validation predicate using the HapiContext (Camel 2.14)

The HAPI Context is always configured with a ValidationContext (or a ValidationRuleBuilder), so you can access the validation rules indirectly. Furthermore, when unmarshalling the HL7DataFormat forwards the configured HAPI context in the CamelHL7Context header, and the validation rules of this context can be easily reused:

...

HL7 Acknowledgement expression

A common task in HL7v2 processing is to generate an acknowledgement message as response to an incoming HL7v2 message, e.g. based on a validation result. The ack expression lets us accomplish this very elegantly:

...

More Samples

In the following example, a plain String HL7 request is sent to an HL7 listener that sends back a response:

...

In the next sample, HL7 requests from the HL7 listener are routed to the business logic, which is implemented as plain POJO registered in the registry as hl7service.

...

Here we process the incoming data as plain String and send the response also as plain String:

...

Then the Camel routes using the RouteBuilder may look as follows:

...

Note that by using the HL7 DataFormat the Camel message headers are populated with the fields from the MSH segment. The headers are particularly useful for filtering or content-based routing as shown in the example above.

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