The following error is generated when attempting to connect to the Service Desk REST URL for Mobile APP:
"Error connecting to ServiceDesk Manager REST URL"
With the logging turned up to ALL through the USS Group Control Panel, the following is noted in the USS Liferay Log:
WARN [ExternalSourceData:313] Error occurred while testing of the WADL: SDM Mobile APP URL/caisd-rest/rest_access/?_wadl
javax.net.ssl.SSLException: Received fatal alert: protocol_version
If the "Received fatal alert: protocol_version" error is received in the Liferay log, then this generally refers to a TLS mismatch in the environment.
Running a SSLTest.java from https://wiki.apache.org/tomcat/tools, against the SDM host name will generate a list of TLS protocols which are accepted.
By default USS uses Java 1.7, as per: https://blogs.oracle.com/java-platform-group/diagnosing-tls,-ssl,-and-https, Java 1.7 defaults to TLSv1.
If TLSv1 is not listed as a supported version from the SSLTest.java, adding the supported version such as: "wrapper.java.additional.27=-Dhttps.protocols=TLSv1.1,TLSv1.2" to the USS wrapper.conf file located in the following location: USSROOT\SelfService\OSOP\tomcat-7.0.40\bin should address the issue.
Then recycle USS services and the Mobile APP Data Source should be able to connect.