You want to use WLST to v ew metrics for a running domain.

Similar to the configuration information, WebLogic Server runtime MBeans are arranged in a hierarchical data structure. When connected to an Administration Server, you access the runtime MBean hierarchy by entering the serverRuntime or the domainRuntime command. The serverRuntime command places WLST at the root of the server runtime management objects, ServerRuntimeMBean; the domainRuntime command, at the root of the domain-wide runtime management objects, DomainRuntimeMBean.