= HL7 DataFormat
:doctitle: HL7
:shortname: hl7
:artifactid: camel-hl7
:description: Marshal and unmarshal HL7 (Health Care) model objects using the HL7 MLLP codec.
:since: 2.0
:supportlevel: Stable
:tabs-sync-option:
//Manually maintained attributes
:camel-spring-boot-name: hl7

*Since Camel {since}*

The HL7 component is used for working with the HL7 MLLP protocol and
http://www.hl7.org/implement/standards/product_brief.cfm?product_id=185[HL7
v2 messages] using the https://hapifhir.github.io/hapi-hl7v2/[HAPI library].

This component supports the following:

* HL7 MLLP codec for xref:ROOT:mina-component.adoc[Mina]
* HL7 MLLP codec for xref:ROOT:netty-component.adoc[Netty]
* Type Converter from/to HAPI and String
* HL7 DataFormat using the HAPI library

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

[source,xml]
----
<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 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 xref:ROOT:mina-component.adoc[camel-mina] or
xref:ROOT:netty-component.adoc[camel-netty] component is used with the
`HL7MLLPCodec` (mina) or `HL7MLLPNettyDecoder/HL7MLLPNettyEncoder`
(Netty).

HL7 MLLP codec can be configured as follows:

[width="100%",cols="10%,10%,80%",options="header",]
|===
|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 (a
http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html[charset
name]) to use for the codec. If not provided, Camel will use the
http://docs.oracle.com/javase/6/docs/api/java/nio/charset/Charset.html#defaultCharset()[JVM
default Charset].

|`produceString` |`true` |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.

|`convertLFtoCR` |`false` |Will convert `\n` to `\r` (`0x0d`, 13 decimal) as HL7 stipulates `\r` as
segment terminators. The HAPI library requires the use of `\r`.
|===

=== 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`:

[source,xml]
----
<endpoint id="hl7MinaListener" uri="mina:tcp://localhost:8888?sync=true&amp;codec=#hl7codec"/>
----

*sync=true* indicates that this listener is synchronous and therefore
will return a HL7 response to the caller. The HL7 codec is set up 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:

[source,xml]
----
<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:

[source,java]
----
from("hl7MinaListener")
  .bean("patientLookupService");
----

This is a basic 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:

[source,xml]
----
<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:

[source,java]
----
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
    }
----

=== 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`:

[source,xml]
----
<endpoint id="hl7NettyListener" uri="netty:tcp://localhost:8888?sync=true&amp;encoders=#hl7encoder&amp;decoders=#hl7decoder"/>
----

*sync=true* indicates that this listener is synchronous and therefore
will return a HL7 response to the caller. The HL7 codec is set up 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:

[source,xml]
----
<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:

[source,java]
----
from("hl7NettyListener")
  .bean("patientLookupService");
----

== 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.

== 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 look up a patient with the patient ID
`0101701234`.

[source,text]
----
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:

[source,java]
----
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:

[source,java]
----
QRY_A19 msg = exchange.getIn().getBody(QRY_A19.class);
String patientId = msg.getQRD().getWhoSubjectFilter(0).getIDNumber().getValue();
----

== HL7 DataFormat

The `camel-hl7` JAR ships with a HL7 data format that can
be used to marshal or unmarshal HL7 model objects.

// dataformat options: START
include::partial$dataformat-options.adoc[]
// dataformat options: END


* `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:

[source,java]
----
  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:

[source,java]
----
  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.

=== 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.


=== 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:

[source,java]
----
  from("direct:hl7in")
    .marshal().hl7()
    .to("jms:queue:hl7out");

  from("jms:queue:hl7out")
    .unmarshal().hl7()
    .to("patientLookupService");
----

== Message Headers

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

[width="100%",cols="40%,20%,40%",options="header",]
|===
|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`

|`CamelHL7Context` | |`contains the
https://hapifhir.github.io/hapi-hl7v2/base/apidocs/ca/uhn/hl7v2/HapiContext.html[HapiContext]
that was used to parse the message`

|`CamelHL7Charset` |`MSH-18` |`UNICODE UTF-8`
|===

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

== 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
https://repo1.maven.org/maven2/ca/uhn/hapi/hapi-base[base library] and
several structure libraries, one for each HL7v2 message version:

* https://repo1.maven.org/maven2/ca/uhn/hapi/hapi-structures-v21[v2.1
structures library]
* https://repo1.maven.org/maven2/ca/uhn/hapi/hapi-structures-v22[v2.2
structures library]
* https://repo1.maven.org/maven2/ca/uhn/hapi/hapi-structures-v23[v2.3
structures library]
* https://repo1.maven.org/maven2/ca/uhn/hapi/hapi-structures-v231[v2.3.1
structures library]
* https://repo1.maven.org/maven2/ca/uhn/hapi/hapi-structures-v24[v2.4
structures library]
* https://repo1.maven.org/maven2/ca/uhn/hapi/hapi-structures-v25[v2.5
structures library]
* https://repo1.maven.org/maven2/ca/uhn/hapi/hapi-structures-v251[v2.5.1
structures library]
* https://repo1.maven.org/maven2/ca/uhn/hapi/hapi-structures-v26[v2.6
structures library]

By default `camel-hl7` only references the HAPI
https://repo1.maven.org/maven2/ca/uhn/hapi/hapi-base[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:

[source,xml]
----
<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>
----


include::spring-boot:partial$starter.adoc[]
