EAP6 documentation contain a topic dedicated to management APIs usage
- http://documentation-devel.engineering.redhat.com/site/documentation/en-US/JBoss_Enterprise_Application_Platform/6.4/html-single/Administration_and_Configuration_Guide/index.html#Management_Application_Programming_Interfaces_APIs

Only CLI and Web console are currently mentioned in EAP 7 Configuration guide.

HTTP API
EAP6 documentation - http://documentation-devel.engineering.redhat.com/site/documentation/en-US/JBoss_Enterprise_Application_Platform/6.4/html-single/Administration_and_Configuration_Guide/index.html#Management_Application_Programming_Interfaces_APIs
Upstream documentation - https://docs.jboss.org/author/display/WFLY10/The+HTTP+management+API
Other references - http://www.mastertheboss.com/jboss-server/jboss-script/managing-jboss-wildfly-using-httpjson-api

Native API
EAP6 documentation - http://documentation-devel.engineering.redhat.com/site/documentation/en-US/JBoss_Enterprise_Application_Platform/6.4/html-single/Administration_and_Configuration_Guide/index.html#Management_Application_Programming_Interfaces_APIs
Upstream documentation - https://docs.jboss.org/author/display/WFLY10/The+native+management+API

JMX
JMX beans can be accessed remotely by monitoring tools like JConsole ($JBOSS_HOME/bin/jconsole.* - see JBEAP-3319) or programmatically (upstream documentation bellow)
Upstream documentation - https://docs.jboss.org/author/display/WFLY10/JMX+subsystem+configuration
Using JConsole to monitor a remote server (and access MBeans) - http://www.mastertheboss.com/jboss-server/jboss-monitoring/using-jconsole-to-monitor-a-remote-wildfly-server ('remote+http' protocol should be used to get rid of warning logs)