Differences Between LDM 5 and LDM 6

Unidata Program CenterUniversity Corporation for Atmospheric

Research

Presentation Assumptions & Goals

• Assume: you generally understand how the LDM works

• Goals:– Understand specific behavior of LDM

5 & LDM 6– Understand differences in behavior

and how they affect performance

LDM Goals

• RELIABLY deliver data products via the Internet in a timely manner

• Support multiple sources of data products

• Support user-customizable actions on received data products

Data-Feed Topology

Source LDM

LDM LDM

LDMLDM LDM

Upstream LDM 5 Behavior

get nextproduct

sendCOMINGSOON

size > 16 KBdone

send HEREIS

size <= 16 KB

sendNULLPRO

C> 5 m

OKOK

DON’TSEND

OK

send 16 KBBLKDATA

SEND

RECLASSadjust selection

criteria

RECLASS

Downstream LDM 5 Behavior

get nextmessage

what is it?

COMINGSOON

save &reply OK

BLKDATA

BLKDATA

done

replyDON’TSEND

duplicate

replySENDnew

HEREIS

what is it?

save &reply OK

new

replyRECLASS

too old

reply OK

NULLPROC

too old

reconnect

> 12 m

Upstream LDM 6 Behavior

get nextproduct

sendCOMINGSOON

size > max send 1BLKDATA

SEND

sendNULLPRO

C> 30 sec

OK

send HEREISsize <= max

DON’TSEND

adjust selectioncriteria RECLASS

Downstream LDM 6 Behavior

get nextmessage

HEREISsave

whatis it?

COMINGSOON

save

BLKDATA

BLKDATA

done

replyDON’TSEND

duplicate

replySENDnew

replyRECLASS too old

reply OK

NULLPROC

YES

send ISALIVE

> 1 m

reconnectNO

Performance Improvement:

IDS|DDPLUS Feed

Performance Improvement:CONDUIT Feed

Improved Performance Permits Volume Increase

Odd Load-Average Behavior on Thelma