IMF url changed

[bertrandmarc]

It seems the url for IMF changed. It is now possible to get data from IMF in SDMX 2.0, 2.1 and JSON.
SDMX XML: http://datahelp.imf.org/knowledgebase/articles/1952905-sdmx-2-0-and-sdmx-2-1-restful-web-service
SDMX JSON: http://datahelp.imf.org/knowledgebase/articles/667681-using-json-restful-web-service

Unfortunately, to get SDMX XML 2.1 data, one needs to add a parameter format=sdmx-2.1 to all requests, and I don't know how to add that in the sources list.

[khaeru]

Great, thanks for the report.

It's interesting: from that page, it looks like the web service API and URL scheme are those of SDMX 2.0. So it's just that query parameter which allows retrieving messages in SDMX-ML 2.1. I haven't seen a hybrid like that before.

The way to handle this is to set the modify_request_args() hook on a source-specific class. For an example see

sdmx/sdmx/source/ilo.py

Lines 7 to 24 in 30d8145

	def modify_request_args(self, kwargs):
	"""Handle two limitations of ILO's REST service.
	1. Service returns SDMX-ML 2.0 by default, whereas :mod:`sdmx` only
	supports SDMX-ML 2.1. Set ``?format=generic_2_1`` query parameter.
	2. The service does not support values 'parents', 'parentsandsiblings'
	(the default), and 'all' for the ``references`` query parameter.
	Override the default with ``?references=none``.
	.. note:: Valid values are: none, parents, parentsandsiblings,
	children, descendants, all, or a specific structure reference
	such as 'codelist'.
	"""
	super().modify_request_args(kwargs)
	kwargs.setdefault("params", {})
	kwargs["params"].setdefault("format", "generic_2_1")
	kwargs["params"].setdefault("references", "none")

[khaeru]

@bertrandmarc on another look, I am not sure if these pages are current.

• The current base URL is: https://sdmxcentral.imf.org/ws/public/sdmxapi/rest/.
• Using this produces working queries for all the metadata endpoints; these run every day as part of the sdmx1 test suite.
• The data endpoint, for example https://sdmxcentral.imf.org/ws/public/sdmxapi/rest/data/CPI/CPI..PCPI_2009_IX., produces a response with an error message (e.g. in this case "Not enough key values in query, expecting 5 got 4"). I have tried a little to construct a working data query to add to the test suite, but haven't been able to.
• The domain sdmxcentral.imf.org contains the usual IM-JS web explorer, e.g. https://sdmxcentral.imf.org/data/overview.html
• This is different from the domain dataservices.imf.org in two pages you link.

It's entirely possible that IMF is operating two services. Maybe one is a legacy one that will eventually be retired, and the other is a modern one. It's also possible the documentation has not been kept up to date (there are no dates mentioned on the pages you linked).

If this is an important data source, would you mind to get in touch with them to ask what the situation is? Better than trying to guess.