14 Annex 4 – Data Reader and Data Writer Functions

14.1 Schematic

The schematic below is that shown in Section 5.4.

Figure 43: Schematic of a Data Reader, Data Writer, and Query Reader

14.2 Example Interfaces

Data Reader

Figure 44: Example of some Methods of the Data Reader Interface

Data Writer

Figure 45: Example of some Methods of the Data Writer Interface

As you will see the only “methods” that the database application needs to invoke are based on the constructs in the SDMX Information Model (Group key, Series Key, Observation, Attribute). Each different “implementation” of this interface will enable a database (or, indeed, any other) application to read or write an SDMX data set in a specific type of data set message (e.g. SDMX-ML generic, SDMX-ML DSD-specific, SDMX-EDI). The important, and only, thing to understand from the Interface specification is that the database application never changes, no matter what is the input or output format. The format can even be CSV or mathematical format such as R or even a presentation format, depending on the implementation passed to the database application. The interface is the important asset here, and this is structured using the constructs of the SDMX Information Model: the database application need not be concerned with the actual format of the data.

Data Query Reader

Figure 46: Example of some Methods of the Data Query Reader Interface