Hi, the 501 is not an error - this feature is available only for CML product line and is not in CDSW. In fact, there has never been an API to use Experiments in CDSW, which is why there is no documentation here.
However, anything that the UI does can be done on the terminal or in scripts if you reverse engineer the API calls. You can do this using for instance the Network tab in the Developer Tools of your browser. If you navigate around to the Experiments page, you will see that it is making the following request: http://cdsw-domain.com/api/altus-ds-1/ds/listruns
IF you copy the request as cURL, it will be huge and contain a bunch of random headers, but I was able to basically follow the same steps as described in the Jobs API v1 documentation page: https://docs.cloudera.com/cdsw/1.10.2/jobs-pipelines/topics/cdsw-starting-a-job-run-using-the-api.ht...
By adding your legacy API key to the cURL request, you can get a list of all of the expirements with a cURL like this:
curl --user "<Legacy API Key>:" -H "Content-Type: application/json" -X POST <http:// CDSW SERVER>.com/api/altus-ds-1/ds/listruns
You can parse through this list for experiments.
By following a similar procedure you can probably execute experiments... I'm not sure, I didn't really try that. This method is not supported by Cloudera, and the official response would be to upgrade to CML to use API v2. If you try this and have problems, we can't really help on a support ticket, but you can respond here and I might be able to help.
Cheers!