Applies to: BizTalk Server 2006 with
the HL7 1.3 Accelerator
Outline of
the problem
Trailing Delimiters are empty values at
the end of an object in a HL7 ER7 formatted message.
Examples:
Empty
Field
NTE|P|
NTE|P||
Empty component
ORC|1|725^
Empty Subcomponent
ORC|1|||||27&
Empty repeat
OBR|1||||||||027~
Trailing delimiters indicate
the following object exists and is empty, which is quite different
from null, null is an explicit value indicated by a pair of double quotes -> "".
The BizTalk HL7 Accelerator by default does not allow trailing delimiters.
There are three methods to allow trailing delimiters.
NOTE: All Schemas always allow trailing delimiters in
the MSH Segment
Using party identifiers
MSH3.1 – Receive/inbound processing, using this value as a party allows you to configure
the system to allow inbound trailing delimiters.
MSH5.1 – Send/outbound processing, using this value as a party allows you to configure
the system to allow outbound trailing delimiters.
Generally, if you allow inbound trailing delimiters, unless you are willing to programmatically remove all trailing delimiters, then you need to configure
the send to allow trailing delimiters.
Add
the appropriate parties to
the BizTalk Parties list
from these two fields in your message stream.
Open
the BizTalk HL7 Configuration tool and for each party check
the "Allow trailing delimiters (separators)" check box on
the Validation tab.
Disadvantage – Each MSH3.1 and MSH5.1 value must be represented in
the parties list and configured.
Advantage – granular control over system behavior for each inbound/outbound system.
Using instance properties of a pipeline used in a send port or receive location.
Open
the BizTalk Server Administration console
locate
the send port or receive location that contains
the BTAHL72XReceivePipeline or BTAHL72XSendPipeline pipeline.
Open
the properties
To
the right of
the pipeline selected locate
the […] ellipses button
In
the property list, locate
the "TrailingDelimiterAllowed" property and set it to True.
Advantage – All messages through a particular Send Port or Receive Location will allow trailing delimiters.
Disadvantage – Must configure each Send Port or Receive Location. No granular control over which remote parties will send or receive messages with trailing delimiters.
Using a custom pipeline that uses a pre-configured BTA HL7 Pipeline component.
Use Visual Studio to construct a custom receive and send pipeline using
the appropriate assembler or dissasembler.
Set
the component property to "TrailingDelimitersAllowed" to True
Compile and deploy
the custom pipeline
Use
the custom pipeline instead of
the standard pipeline for all HL7 message processing
Advantage – All messages using
the custom pipeline will automatically allow trailing delimiters.
Disadvantage – Requires custom coding and development to create and deploy
the custom pipeline. No granular control over which remote parties will send or receive messages with trailing delimiters.
What does a Trailing Delimiter do to
the XML Schema?
Allowing trailing delimiters does not have
the impact often expected in
the actual XML Schema.
The Schema reproduces
the message with no data loss.Thus,
the message when represented in XML must contain
the extra fields, in order to reproduce
the outbound message.Thus, a trialing delimiter results in an empty XML
field.Trailing Delmiters are not stripped
from the inbound message.
Example:<PID_21>44172</PID_21><PID_21>9257</PID_21> ->
the original maximum number of repeats<PID_21></PID_21> ->
The empty repeated
field
Allowing trailing delimiters not remove
the trailing delimiters
from the message, it simply suppresses
the check that will cause
the message to fail parse with trailing delimiters.
When can you not fix
the problem by enabling trailing delimiters
Each object in a message must have a location in
the target BTAHL7 schema for its content to reside.If you have more objects in
the message than are contained at that location, then enabling trailing delimiters will not resolve
the problem.
The schema must be extended to accommodate
the empty message content.Examples:
Extra
Field
NTE|P||||Only 4 fields in NTE Segment,
the 4th
field exists, but is empty.
Extra component
PID|1|1523|47^^^^^^^Only 5 components in a CX data type,
the 5th component exists, but is empty
Extra subcomponent
ORC|1|||||27&&Only 2 subcomponents in a CQ data type,
the 3rd subcomponent is empty, but exists.
Extra Repeat
PID|1||||||||||||||||||||4419~5217~Only 2 repeats allowed for
the field "Mother's identifier",
the repeat is empty, but exists.
In each of these cases, you must locate
the failing object and extend
the type to allow an additional object of that type.
FieldAdd a
field of ST to
the end of
the segment with a suitable name in
the segments_nnn.xsd
Component
Create a new Custom CX data type (i.e. CX_XtraComp) in
the datatypes_nnn.xsd and add a new component to
the custom CX data type. Update
the field in
the segments_nnn.xsd file to use
the custom data type instead of
the standard datatype.
Subcomponent
Create a new Custom CQ data type that accepts an additional TS value at
the end of
the data type. Create a custom TQ data type that uses
the new custom CQ data type as
the first subcomponent. Modify
the ORC segment to use
the new CQ data type at ORC.7 instead of
the standard CQ data type.
RepeatModify
the Field definition for PID.21 in
the segments_nnn.xsd to allow more repeats in
the field.
