Introduction to the SDMX-JSON Data Message

JSON (JavaScript Object Notation) is a lightweight data-interchange format.

• Text based
• Supports Unicode
• Documented www.json.org
• Standardized RFC4627 ECMA-404
• Language independent (over 30 from ASP to VB)
• Supported by tools (browsers have built-in support)
• Used in production (Google, Facebook, Twitter etc.)

Developers will be able to write software that requests responses in JSON from SDMX RESTful API and processes the data and metadata in the JSON response in order to produce useful data visualizations on the Web.

• Must-have
  • Conforms to the JSON standard ECMA-404.
  • Supports the SDMX 2.1 information model.
  • Supports the full functionality in the SDMX 2.1 RESTful API for data.
  • Supports many different types of visualisations.
  • Streamable on the server.
• Linear (the more/less, the better)
  • Easy: minimal amount of client code required.
  • Fast: few roundtrips, small messages, and fast parsing.

{
  “header”: { ... },
  “errors”: { ... },
  “structure”: { ... },
  “dataSets”: [ ... ]
}

• Header is for technical information: prepared, sender, ...
• Errors is for error messages.
• Structure contains metadata: dimensions and attributes.
• DataSets contains the actual data.
• Examples: flat grouped

• Data message combines structure (e.g. dimensions and attributes) and data (observation and attribute values) in the same message.
• Server will join and merge information from different parts of the SDMX IM (e.g. names for codes) into one response message.
• This avoids multiple requests from the client which saves time and simplifies client code.
• Client does not need to process different parts of the SDMX IM and their relationships.

• Because dimensions and attributes typically take on a limited number of different values we can store them as integers in the dataset and keep the actual values as part of the structure.
• This includes both coded and uncoded attributes.
• The integers map directly to the array indices in the values fields.
• Statistical package R uses a similar method for storing factor (or categorical) variables.

• Supports both flat data sets and data sets with series grouping. Also supports optional grouping of common dimension and attribute values.
• Supports multiple data sets with different actions (update, append, delete, informational).
• Supports hyperlinks to other parts of the IM (e.g. data flows).
• Supports optional annotations.
• Includes human readable names and descriptions for data sets, dimension, attributes etc.
• Supports roles for dimensions/attributes (time etc.)

• Public Review Announcement
• Github Repository
  • SDMX-JSON Draft Documentation
  • SDMX-JSON Sample Files
  • SDMX 2.1 RESTful API tutorial
• Discussion Group
  • SDMX-JSON Google Group

All comments are welcome!
twg@sdmx.org

Data Set

Harmonised Index of Consumer Prices (HICP) for the euro area.

Server

European Central Bank SDMX 2.1 RESTful Web Service