Add support for SDMX

[GregorDeCillia]

It would be very useful if {STATcubeR} could support "SDMX archives" which are generated from STATcube. sdmx archives consist of a metadata component called the "structure definition" and a data part which contains the actual cell values. In order to support that, we would need to add parsers for the xml-based data format.

The generated archives are more or less compatible with the CRAN package rsdmx: https://cran.r-project.org/package=rsdmx, which could be used as a starting point to develop parsers.

Possible usuage: parser function sdmx_table() which generates an object of class sc_data (the parent class for OGD and STATcube-API datasets)

x <- STATcubeR::sdmx_table("path/to/sdmx_archive.zip")
class(x)
#> [2] "sdmx_table" "sc_data" "R6"

There are several advantages of the sdmx format compared to the API

• The structure definition contains information about hierarchical classifications, which are not available via the API
• The download option "sdmx archive" is available even if STATcube is used as a "guest user"
• SDMX is used by other SuperSTAR products such as SuperCROSS

The last point is probably the most compelling one since a direct interface to SuperCROSS would be very helpful for the internal workflows of statistics austria

[GregorDeCillia]

Screenshot: SDMX downloads are available for unregistered users on the external STATcube instance