KB232538: "HTTP error encountered while trying to access a REST service” error occurs when trying to connect to a Web Service in XQuery using client certificates.

SUMMARY:
This issue is currently working as designed and there is an enhancement logged with Strategy technology in order to improve the functionality. The impact is limited to connecting to a Web Service that uses SSL and client certificates. A solution/code fix for this issue is not available in current releases but is being reviewed for a future Strategy release.
 
SYMPTOM:
After testing a Web Service that returns the needed data, and filling up the information for the connection to the Web Service using the steps provided in the Advanced Reporting Guide, when trying to finish the setup and connect, the following error shows:

mstr-rest:: post() failed. HTTP error encountered while trying to access a REST service. Error type: XQuery Engine error

1. Set up a Web Service that uses SSL and client certificates.
2. Test the Web Service by accessing it in any browser in order to see if the information is being returned correctly.
3. In the XQuery Editor, fill up the information for the connection to the Web Service using the instructions provided in the Advanced Reporting Guide, pages 647-649
4. When trying to finish the setup and connect to the service in order to retrieve the data, the error above will show. 
    

CAUSE:
This is working as designed. Currently it is not possible to retrieve data from a Web Service that uses SSL and client certificates using XQuery. An enhancement has been logged to allow for this functionality.
 
ACTION:
Strategy will continue to investigate and post updates as soon as they are available.