Chapter 76. HL7
The HL7 component is used for working with the HL7 MLLP protocol and HL7 v2 messages using the HAPI library.
This component supports the following:
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>{CamelSBVersion}</version> <!-- use the same version as your Camel core version --> </dependency>
76.1. HL7 MLLP protocol
HL7 is often used with the HL7 MLLP protocol, which is a text based TCP socket based protocol. This component ships with a Mina and Netty Codec that conforms to the MLLP protocol so you can easily expose an HL7 listener accepting HL7 requests over the TCP transport layer. To expose a HL7 listener service, the camel-mina or link:camel-netty component is used with the HL7MLLPCodec (mina) or HL7MLLPNettyDecoder/HL7MLLPNettyEncoder (Netty).
HL7 MLLP codec can be configured as follows:
Name | Default Value | Description |
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| The start byte spanning the HL7 payload. |
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| The first end byte spanning the HL7 payload. |
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| The 2nd end byte spanning the HL7 payload. |
| JVM Default | The encoding (a charset name) to use for the codec. If not provided, Camel will use the JVM default Charset. |
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| If true, the codec creates a string using the defined charset. If false, the codec sends a plain byte array into the route, so that the HL7 Data Format can determine the actual charset from the HL7 message content. |
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Will convert |
76.1.1. Exposing an HL7 listener using Mina
In the Spring XML file, we configure a mina endpoint to listen for HL7 requests using TCP on port 8888
:
<endpoint id="hl7MinaListener" uri="mina:tcp://localhost:8888?sync=true&codec=#hl7codec"/>
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:
<bean id="hl7codec" class="org.apache.camel.component.hl7.HL7MLLPCodec"> <property name="charset" value="iso-8859-1"/> </bean>
The endpoint hl7MinaLlistener can then be used in a route as a consumer, as this Java DSL example illustrates:
from("hl7MinaListener") .bean("patientLookupService");
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:
<bean id="patientLookupService" class="com.mycompany.healthcare.service.PatientLookupService"/>
The business logic can be implemented in POJO classes that do not depend on 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 }
76.1.2. Exposing an HL7 listener using Netty (available from Camel 2.15 onwards)
In the Spring XML file, we configure a netty endpoint to listen for HL7 requests using TCP on port 8888
:
<endpoint id="hl7NettyListener" uri="netty:tcp://localhost:8888?sync=true&encoders=#hl7encoder&decoders=#hl7decoder"/>
sync=true indicates that this listener is synchronous and therefore will return a HL7 response to the caller. The HL7 codec is setup with encoders=#hl7encoder*and*decoders=#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:
<bean id="hl7decoder" class="org.apache.camel.component.hl7.HL7MLLPNettyDecoderFactory"/> <bean id="hl7encoder" class="org.apache.camel.component.hl7.HL7MLLPNettyEncoderFactory"/>
The endpoint hl7NettyListener can then be used in a route as a consumer, as this Java DSL example illustrates:
from("hl7NettyListener") .bean("patientLookupService");
76.2. 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.
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.
76.3. HL7v2 Model using HAPI
The HL7v2 model uses Java objects from the HAPI library. Using this library, you can encode and decode from the EDI format (ER7) that is mostly used with HL7v2.
The sample below is a request to lookup a patient with the patient ID 0101701234
.
MSH|^~\\&|MYSENDER|MYRECEIVER|MYAPPLICATION||200612211200||QRY^A19|1234|P|2.4 QRD|200612211200|R|I|GetPatient|||1^RD|0101701234|DEM||
Using the HL7 model you can work with a ca.uhn.hl7v2.model.Message
object, e.g. to retrieve a patient ID:
Message msg = exchange.getIn().getBody(Message.class); QRD qrd = (QRD)msg.get("QRD"); String patientId = qrd.getWhoSubjectFilter(0).getIDNumber().getValue(); // 0101701234
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:
QRY_A19 msg = exchange.getIn().getBody(QRY_A19.class); String patientId = msg.getQRD().getWhoSubjectFilter(0).getIDNumber().getValue();
76.4. HL7 DataFormat
The camel-hl7
JAR ships with a HL7 data format that can be used to marshal or unmarshal HL7 model objects.
The HL7 dataformat supports 1 options, which are listed below.
Name | Default | Java Type | Description |
---|---|---|---|
validate |
| Whether to validate the HL7 message Is by default true. |
-
marshal
= from Message to byte stream (can be used when responding using the HL7 MLLP codec) -
unmarshal
= from byte stream to Message (can be used when receiving streamed data from the HL7 MLLP
To use the data format, simply instantiate an instance and invoke the marshal or unmarshal operation in the route builder:
DataFormat hl7 = new HL7DataFormat(); from("direct:hl7in") .marshal(hl7) .to("jms:queue:hl7out");
In the sample above, the HL7 is marshalled from a HAPI Message object to a byte stream and put on a JMS queue.
The next example is the opposite:
DataFormat hl7 = new HL7DataFormat(); from("jms:queue:hl7out") .unmarshal(hl7) .to("patientLookupService");
Here we unmarshal the byte stream into a HAPI Message object that is passed to our patient lookup service.
76.4.1. Segment separators
Unmarshalling does not automatically fix segment separators anymore by converting \n
to \r
. If you
need this conversion, org.apache.camel.component.hl7.HL7#convertLFToCR
provides a handy Expression
for this purpose.
76.4.2. Charset
Both marshal and unmarshal
evaluate the charset provided in the field MSH-18
. If this field is empty, by default the charset contained in the corresponding Camel charset property/header is assumed. You can even change this default behavior by overriding the guessCharsetName
method when inheriting from the HL7DataFormat
class.
There is a shorthand syntax in Camel for well-known data formats that are commonly used. Then you don’t need to create an instance of the HL7DataFormat
object:
from("direct:hl7in") .marshal().hl7() .to("jms:queue:hl7out"); from("jms:queue:hl7out") .unmarshal().hl7() .to("patientLookupService");
76.5. Message Headers
The unmarshal operation adds these fields from the MSH segment as headers on the Camel message:
Key | MSH field | Example |
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All headers except CamelHL7Context
are String
types. If a header value is missing, its value is null
.
76.6. 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:
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:
<dependency> <groupId>ca.uhn.hapi</groupId> <artifactId>hapi-structures-v24</artifactId> <version>2.2</version> <!-- use the same version as your hapi-base version --> </dependency> <dependency> <groupId>ca.uhn.hapi</groupId> <artifactId>hapi-structures-v25</artifactId> <version>2.2</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>2.2</version> </dependency>
76.7. Spring Boot Auto-Configuration
When using hl7 with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:
<dependency> <groupId>org.apache.camel.springboot</groupId> <artifactId>camel-hl7-starter</artifactId> </dependency>
The component supports 4 options, which are listed below.
Name | Description | Default | Type |
---|---|---|---|
camel.dataformat.hl7.enabled | Whether to enable auto configuration of the hl7 data format. This is enabled by default. | Boolean | |
camel.dataformat.hl7.validate | Whether to validate the HL7 message Is by default true. | true | Boolean |
camel.language.hl7terser.enabled | Whether to enable auto configuration of the hl7terser language. This is enabled by default. | Boolean | |
camel.language.hl7terser.trim | Whether to trim the value to remove leading and trailing whitespaces and line breaks. | true | Boolean |