I hope that by DS you mean data source. You can look up the mbeans created for the datasource. One of the mbeans created is named "jboss.jca:name=XXX,service=DataSourceBinding" where XXX is the datasource name. So looking up the mbeans whose names fit this pattern will return one mbean for each data source. You can then query the mbean name to get the datsource name.
This will get you started with mbean lookup:
http://community.jboss.org/wiki/HowDoIGetRemoteAccessToMyMBean
http://community.jboss.org/thread/52375
http://community.jboss.org/message/251586