HL7 Transport

The HL7 transport (new in Carbon 4.0) allows you to handle Health Level 7 International (HL7) messages. The following sections describe how to install, enable, and configure the HL7 transport:

Installing the HL7 feature

The HL7 transport is available as a feature in WSO2 Enterprise Service Bus (WSO2 ESB). For instructions on installing the HL7 feature, see Installing the Axis2 Transport HL7 Feature.

Enabling the transport

After you install the HL7 transport, it is configured in the <ESB_HOME>/repository/conf/axis2/axis2.xml file as follows:

<transportReceiver name="hl7" class="org.wso2.carbon.business.messaging.hl7.transport.HL7TransportListener">
    <parameter name="port">9292</parameter>
</transportReceiver>
<transportSender name="hl7" class="org.wso2.carbon.business.messaging.hl7.transport.HL7TransportSender">
    <!--parameter name="non-blocking">true</parameter-->
</transportSender>

Creating an HL7 proxy service

For information on creating a proxy service that uses the HL7 transport, see Creating an HL7 Proxy Service.

Configuring the transport

As of version 4.0.0, you can optionally configure the following behavior of the HL7 transport.

HL7 conformance profile support

Add the parameter "transport.hl7.ConformanceProfilePath" in the proxy service to point to a URL where the conformance profile XML can be found.

HL7 message pre-processing

Add the parameter "transport.hl7.MessagePreprocessorClass" to point to an implementation class of the interface "org.wso2.carbon.business.messaging.hl7.common.HL7MessagePreprocessor" that is used to process raw HL7 messages before parsing them, so that potential errors in the messages can be rectified using the transport.

Capability to enable/disable automatic ACK/NACK

You can enable or disable automatic message acknowledgement and validation. When automatic message acknowledgement is enabled, an ACK is immediately sent back to the client after receiving a message. When it is disabled, the user is given control to send back an ACK/NACK message from an ESB sequence after any message validations or related tasks. Different types of message validations done at the message builder are removed for behavioral consistency of the message builder with the transport.

Following are some example usage scenarios:

1. When using a transport such as HTTP, to create an ACK/NACK message from an HL7 message in the flow, specify an axis2 scope message context property "HL7_GENERATE_ACK", and set its value to true. This ensures that an ACK/NACK message is created automatically when a message is sent out (using the HL7 formatter). By default, an ACK message is created. If a NACK message is required instead, use the message context properties "HL7_RESULT_MODE" and "HL7_NACK_MESSAGE".

2. Add the following parameters to the proxy service:

<proxy>...
   <parameter name="transport.hl7.AutoAck">true|false</parameter> <!-- default is true -->
   <parameter name="transport.hl7.ValidateMessage">true|false</parameter> <!-- default is true -->
</proxy> 

3. When ‘AutoAck’ is false, you can set the following properties inside an ESB sequence.

<property name="HL7_RESULT_MODE" value="ACK|NACK" scope="axis2" /> <!-- notice the properties should be in axis2 scope --> 

4. When the result mode is ‘NACK’, you can use the following property to provide a custom description of the error message.

<property name="HL7_NACK_MESSAGE" value="<ERROR MESSAGE>" scope="axis2" />

5. You can use the property "HL7_RAW_MESSAGE" in the axis2 scope to retrieve the original raw EDI format HL7 message in an ESB sequence. The user doesn't have to convert from XML to EDI again, so this usage may be particularly helpful inside a custom mediator.

6. Set the Java system property "ca.uhn.hl7v2.llp.charset" to control the encoding type of incoming messages.