acknowledgementmessage. The MLLP V2 acknowledgement protocol is synchronous: the
sourcesystem will not send new HL7 content until an acknowledgement for the previous HL7
contenthas been received.
Ifthe HL7 content (a query in the example below) triggers the sending of HL7 content (a
response)by the destination system, then this HL7 content is framed in a block and sent. MLLP
hasno knowledge of the HL7 content, nor does it base any part of its behavior on HL7 content.
Withthe TCP/IP HL7 Adapter, a database is used to persist the message.
Ininbound mode, once the message is received by the HL7 Adapter, it is persisted into the
databaseand a commit acknowledgement is sent to the sender before the HL7 message is passed
tothe Collaboration level. If the persistence fails, a negative acknowledgement is sent to the
senderand the Collaboration receives null as its message. Inside the Collaboration, the message
receivedis null and the Collaboration returns without proceeding.
Ifthe message received is a duplicate message and if an ACK/NAK is already available in the
persistencedatabase, the same is retrieved from the database and sent to the sender. The
Collaborationreceives null as the received message.
Source/Destination
HL7 Content: Query()
HL7 Content: Query()
Commit Acknowledgement()
Commit Acknowledgement()
Destination/Source
HL7 Query/Response
FIGURE23 InteractionDiagram
MLLPV2and the Sample Projects
SunAdapterfor TCP/IP HL7 User's Guide 145