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Data Interchange. The Problems. Codes, numbers and meaning Implied codes and units Within organisations Between organisations Between countries. Codes. Codes only have meaning when both sides agree on the meaning Me - 10=rainfall You - 10=water level Result - Chaos Me - PL=Polyethylene
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The Problems • Codes, numbers and meaning • Implied codes and units • Within organisations • Between organisations • Between countries
Codes • Codes only have meaning when both sides agree on the meaning • Me - 10=rainfall • You - 10=water level • Result - Chaos • Me - PL=Polyethylene • You - PL=Polyproplyene • Result - Chaos
Discrete Codes • Taken from limited possible range • May be possible to map one to another • Rainfall and water level can be coded anything, and always mapped • Quality codes cannot easily map between one organisation and another • Rock types would be nearly impossible
Fuzzy Codes • Codes taken from one or more continuous ranges • SLMS = Sandy limestone with mud streaks • 2=mainly good edited data with occasional gaps of <60 minutes • 16=good enough to use
Fuzzy codes • Need to impose limited discrete codes for mapping purposes • Will lose information during exchange • SLMS = Sandy limestone with mud streaks becomesLMST - Limestone • 2 and 16 become1 - Good
Numbers • Numbers can only be interchanged in the same units • Me - rainfall in mm • You - rainfall in points • Result - chaos
Time • Time datum changes from place to place • 12:15 - Eastern Standard, Central, Greenwich Mean, Pacific Standard? • Hydstra does not record time datum anywhere
Implied Units • Temperature in gaugings • Pipe diameters in groundwater • Every real number in a database should have a unitcode next to it - but it doesn’t!
Database Structures • You might be running HYDSYS 5, and I am running HYDSYS 6. • HYDSYS 6 combines sections into one table • Cannot export sections from 6 to 5
Solutions • If everyone uses the same codes, units, datums, versions, there are no problems • IMPEXP within organisations works quite well
Problems • If different organisations use different codes, you cannot exchange data. • One workaround is to keep separate systems in different directories • Another possible solution is to agree on common codes for interchange and provide translations at each end • HYDSYS 6 is much more strict about invalid codes
Partial Solutions • HYTRAN does some conversions - variables, units, quality codes in TS data • Some rating conversion is supplied • IMPEXP can upgrade HYDSYS 5 exports before import to HYDSYS 6 (ish) • No general solution • No agreed interchange standards
Where To Next? • More problems can be solved, but they will take a lot of work • The organisations with the greatest interest are small - eg MDBC, universities, consultants • It will probably never be possible to exchange heavily coded data like groundwater data
Project? • Is there financial interest in proceeding? • Is Federal funding available? • Do we care? • No more work on interchange will be done without $$$