Note– The TCP/IP HL7 Adapter includes internal counters that keep track of all error
conditions.
GeneralFunctionality
Thissection explains the Adapter’sgeneral functions and features. It includes the following
topics:
■“Non-blockingI/O” on page 20
■“HL7Sequence Numbering Protocol” on page 20
■“FailedMessage Handling” on page 21
■“RecourseActions” on page 21

Non-blockingI/O

Thenon-blocking I/O feature prevents the Adapter from locking up when attempting to read or
writedata blocks, allowing the Adapter to continue its operation in case of any communication
errors.If the read attempt fails for a congurable number of times, the Adapter exits or resets its
connectionto the external system, depending on its conguration. In the event of a failed write,
theAdapter can resume its write operation to pick up where it previously left o until the entire
messageis successfully sent.
Withoutthis feature, the Adapter might lock up when a read or write failure occurs and be
unresponsiveto all external messages, including requests from the user or the Enterprise
Monitor(for status).

HL7Sequence Numbering Protocol

TheAdapter can be congured to use HL7 sequence numbering. The negotiation and
incrementationof this number is automatically performed by the Adapter. For more details on
HL7sequence numbering, refer to Appendix C (Lower Layer Protocols) of the HL7 Standard
forthe HL7 version you are using.
Whenthe Adapter is congured for HL7 sequence numbering, the sequence number le opens
whenthe Adapter starts up. If the sequence number le does not exist, one is created and
populatedwith a zero sequence number. The sequence number le is updated on the inbound
Adapterwhen the Adapter generates the HL7 ACK (this process is transparent to the user), and
whenthe outbound Adapter receives the HL7 ACK from the external system.
Ifyou want to change the sequence number at runtime, you need to suspend the Adapter, edit
andsave the sequence number le, and reactivate the Adapter. To force the Adapter to
resynchronizeits sequence number with the external system, you need to suspend the Adapter,
editthe le so it contains a “-1”, and then reactivate the Adapter.
SunAdapterfor TCP/IP HL7 Overview
SunAdapterfor TCP/IP HL7 User's Guide • Oc tober 200920