About the SDMX-JSON Format
SDMX-JSON is a specific JSON-based format defined under the SDMX standard, which is used to describe and transmit statistical data. In SDMX the measurement of a phenomenon (e.g. a population count) is known as an “observation”. Observations are described and uniquely identified by a combination of “dimension” values (e.g. a country and a year). “Attributes” allow further adding useful information but do not help identifying statistical data (e.g. observation status). Observations of a same kind – identifiable by the same dimensions – are grouped into a “dataset”. The format also allows for an optional intermediate grouping of the observations for all values of one of the dimensions, called “series”. Specifically, the grouping of the observations for all available time periods is a so-called “time series” (e.g. the population counts for all years for a specific country). Similarly, groups can be made with any dimension. Alternatively, no grouping results in a flat list of all observations in the dataset. Descriptive information on the dataset, dimensions and attributes is called “structural metadata” and is returned within the “structure” part of the message.
The structural metadata for all and only the actually returned observations are included in the SDMX-JSON response message. If possible, in order to minimise repetition, each dimension/attribute is specified at the highest possible grouping level. Dimensions and attributes specified on dataset and series level have the same values for all observations throughout the dataset or series respectively.
To uniquely identify observations in the SDMX-JSON message, the indexes of the corresponding dimension values as defined in the “structure” part of the message at series and observation level are concatenated into the series’ or observation’s property name. Here, the indexes are ordered in the pre-defined order of dimensions as defined in the “structure” part of the message and separated between each other by a colon character.
The concrete values of attributes at series and observation level are also returned through their index as defined in the “structure” part of the message.
The following documents describe the SDMX-JSON standard in more detail:
It is important to note that both the draft specification and the API implementation are continuously being improved; there are likely to be changes in the future to ensure the API is aligned to the standard.