LowerLayer Protoco l
Thissection describes the two supported envelope types used in the HL7 protocol:
■HLLP(Hybrid Lower Layer Protocol)
■MLLP(Minimal Lower Layer Protocol)
Bothenvelope types use the following conguration parameters. For more information on
theseparameters, see “Lower Layer Protocol — TCP/IP HL7 V2 Inbound Adapter” on page 40
or“Lower Layer Protocol — TCP/IP HL7 V2 Outbound Adapter” on page 55.
■StartBlock Character
■EndData Character
■EndBlock Character

MLLP

TheMLLP envelope consists of a Start of Block component, a Data component, an End of Data
component,and an End of Block component. The size of the HL7 Data eld is determined by
thelength of the data (number of bytes between start and end), with a maximum size of 99999
Bytes.

HLLP

TheHLLP envelope consists of a Start of Block component, a ”D’ (Data) or ”N’ (NAK)
indicator,an HL7 Version component, a Carriage Return, a Data component, a Block Size
component,a Block Checksum component, an End of Data component, and an End of Block
component.The size of the HL7 Data eld is determined by the length of the data (number of
bytesbetween start and end), with a maximum size of 99999 Bytes.
HL7Acknowledgment Level
TheAdapter supports sending and receiving both HL7 acknowledgement types:
■Applicationacknowledgment: This acknowledgement is sent when the message is
successfullyreceived.
■Commit(accept) acknowledgment: This acknowledgement is sent after the message is
successfullyand functionally processed by one receiving system.
Journaling
TheAdapter provides the option to journal successfully received or sent messages and their
correspondingACKs. The messages are sent to a JMS queue or topic, depending on how you
congurethe Adapter, and the ACKs are stored as a JMS property, HL7_ACK, of that message.
SunAdapterfor TCP/IP HL7 Overview
SunAdapterfor TCP/IP HL7 User's Guide 23