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--- fimex:todo:parameterfunction [2014-04-23 13:12:11]
heikok created
+++ fimex:todo:parameterfunction [2022-05-31 09:29:32]
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-====== Project-Plan: easy function-based / parameter selection ======
-===== Problem =====
-Meteo. input data does not allways contain all parameters since gridded data usually is huge, while it is relatively easy to calculate them from other parameters, e.g. relative humidity <-> specific humidity. An end user just want to have 'his' parameter, independently if this is stored on disk or calculated on demand. Fimex currently does not support an easily configurable interface to support calculated parameters.
-[[http://diana.met.no|Diana]] supports on demand parameters in the FieldCompute setup. But FieldCompute can only be used from within diana and is as such restricted by Graphical Users, i.e. ~2s for display of data. And independent approach would avoid duplication and improve reliability if such on demand parameters could be added to all applications reading data via the fimex.
-===== Hard Requirements =====
-  * The on demand parameters shall be usable from all programs which can read data via the libfimex interface, independently if it is C/C++, Fortran2003, R, the command-line or any future language.
-  * Users shall be able to change the order of functions, or the selected parameter for the on-demand function. (e.g. setup-files or strings in an input form)
-  * It shall be possible to have common on-demand rules, while it also must be possible to overrule or extend these common rules.
-  * On demand parameters must be recurse, i.e. one on demand parameter shall be able to rely on another on demand parameter.
-  * Users shall be able to switch on and off  on demand parameters.
-  * It shall be possilbe to create an on-demand parameter from multiple CDMReader sources (as long as the data has the same grid)
-  * The system must work with both variable-names and CF standard_names and automatically select the first / best.
-===== Soft Requirements =====
-  * The on demand parameters should be callable in the standard fimex way, i.e. extend a CDMReader, show an overview of all parameters, both real and on-demand and fetch the data by 'getDataSlice'.
-  * The software should have a clear separation from other fimex functionality, e.g. it should create a lib of its own, and it should reside in an own (sub-)catalog. It might be useful to integrate it into the fimex infrastruction, e.g. build / test infrastruction and even the same 'tar'-file (as long as the lib is a //configure// flag.)