Sun Microsystems Sun Adapter IP HL 7 - Manual (Page 145)

acknowledgement message. The MLLP V2 acknowledgement protocol is synchronous: the
source system will not send new HL7 content until an acknowledgement for the previous HL7
content has been received.
If the 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
has no knowledge of the HL7 content, nor does it base any part of its behavior on HL7 content.
With the TCP/IP HL7 Adapter, a database is used to persist the message.
In inbound mode, once the message is received by the HL7 Adapter, it is persisted into the
database and a commit acknowledgement is sent to the sender before the HL7 message is passed
to the Collaboration level. If the persistence fails, a negative acknowledgement is sent to the
sender and the Collaboration receives null as its message. Inside the Collaboration, the message
received is null and the Collaboration returns without proceeding.
If the message received is a duplicate message and if an ACK/NAK is already available in the
persistence database, the same is retrieved from the database and sent to the sender. The
Collaboration receives null as the received message.
Source/Destination
HL7 Content: Query()
HL7 Content: Query()
Commit Acknowledgement()
Commit Acknowledgement()
Destination/Source
HL7 Query/Response
FIGURE 23 Interaction Diagram
MLLP V2 and the Sample Projects
Sun Adapter for TCP/IP HL7 User's Guide 145