HL7 Terser Language

Available as of Camel version 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.

HL7 Terser Language options

The HL7 Terser language supports 1 options, which are listed below.

Name Default Java Type Description

trim

true

Boolean

Whether to trim the value to remove leading and trailing whitespaces and line breaks

Spring Boot Auto-Configuration

When using Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

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

The component supports 2 options, which are listed below.

Name Description Default Type

camel.language.hl7terser.enabled

Enable terser language

true

Boolean

camel.language.hl7terser.trim

Whether to trim the value to remove leading and trailing whitespaces and line breaks

true

Boolean

Samples:

   import static org.apache.camel.component.hl7.HL7.hl7terser;

   // extract patient ID from field QRD-8 in the QRY_A19 message above and put into message header
   from("direct:test1")
      .setHeader("PATIENT_ID", hl7terser("QRD-8(0)-1"))
      .to("mock:test1");

   // continue processing if extracted field equals a message header
   from("direct:test2")
      .filter(hl7terser("QRD-8(0)-1").isEqualTo(header("PATIENT_ID"))
      .to("mock:test2");

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:

import static org.apache.camel.component.hl7.HL7.messageConformsTo;
import ca.uhn.hl7v2.validation.impl.DefaultValidation;

   // Use standard or define your own validation rules
   ValidationContext defaultContext = new DefaultValidation();

   // Throws PredicateValidationException if message does not validate
   from("direct:test1")
      .validate(messageConformsTo(defaultContext))
      .to("mock:test1");

HL7 Validation predicate using the HapiContext

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:

import static org.apache.camel.component.hl7.HL7.messageConformsTo;
import static org.apache.camel.component.hl7.HL7.messageConforms

  HapiContext hapiContext = new DefaultHapiContext();
  hapiContext.getParserConfiguration().setValidating(false); // don't validate during parsing

  // customize HapiContext some more ... e.g. enforce that PID-8 in ADT_A01 messages of version 2.4 is not empty
  ValidationRuleBuilder builder = new ValidationRuleBuilder() {
      @Override
      protected void configure() {
         forVersion(Version.V24)
              .message("ADT", "A01")
              .terser("PID-8", not(empty()));
         }
      };
  hapiContext.setValidationRuleBuilder(builder);

  HL7DataFormat hl7 = new HL7DataFormat();
  hl7.setHapiContext(hapiContext);

  from("direct:test1")
     .unmarshal(hl7)                // uses the GenericParser returned from the HapiContext
     .validate(messageConforms())   // uses the validation rules returned from the HapiContext
                                    // equivalent with .validate(messageConformsTo(hapiContext))
     // route continues from here

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:

import static org.apache.camel.component.hl7.HL7.messageConformsTo;
import static org.apache.camel.component.hl7.HL7.ack;
import ca.uhn.hl7v2.validation.impl.DefaultValidation;

  // Use standard or define your own validation rules
   ValidationContext defaultContext = new DefaultValidation();

   from("direct:test1")
      .onException(Exception.class)
         .handled(true)
         .transform(ack()) // auto-generates negative ack because of exception in Exchange
         .end()
      .validate(messageConformsTo(defaultContext))
      // do something meaningful here

      // acknowledgement
      .transform(ack())