You are using Oracle Goldengate 21.3, the classical one (not the microservices architecture based one), and you want to monitor the activities of Goldengate?
You installed an Oracle Enterprise Manager, deployed the Goldengate Plugin, installed Jagent / Monitoring Agent 12.2.1.2 into the targets and configured them.
You saw PMSRVR and JAGENT processes in GGSCI outputs, you started them, and they were in RUNNING status, and you told yourself: okay, so far so good.
Then, you used Oracle Enterprise Manager's auto discovery for discovering thee monitoring agents by the using relevant information like the port , host and etc..
Oracle Enterprise Manager didn't get any errors and discovery completed successfully, but! nothing changed? Couldn't Goldengate Monitoring agents be discovered?
Then you jumped into the servers where you installed those agents and checked the listen port by using netstat and everything seemed fine.
However; when you checked the log of those agents, you saw something like the following.
Could not get WSInstance Information , [[com.goldengate.monitor.model.AgentCommunicationException: Failed to get Registry.
at com.goldengate.monitor.jagent.comm.ws.ManagerWSApi.getInstanceInfo(ManagerWSApi.java:239)
at com.goldengate.monitor.jagent.comm.ws.ManagerWSAdapter.getInstanceInfoNative(ManagerWSAdapter.java:105)
at com.goldengate.monitor.jagent.comm.impl.ManagerFacadeImpl.fillInstanceMap(ManagerFacadeImpl.java:259)
at com.goldengate.monitor.jagent.comm.impl.ManagerFacadeImpl.getInstances(ManagerFacadeImpl.java:253)
at com.goldengate.monitor.jagent.jmx.MBeansContainerImpl.createMBeans(MBeansContainerImpl.java:344)
at com.goldengate.monitor.jagent.jmx.MBeansContainerImpl$1.run(MBeansContainerImpl.java:836)
at java.lang.Thread.run(Thread.java:750)
Caused by: java.lang.IllegalArgumentException: source parameter must not be null
at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:119)
at com.sun.xml.internal.ws.message.AbstractMessageImpl.readPayloadAsJAXB(AbstractMessageImpl.java:135)
at com.sun.xml.internal.ws.api.message.MessageWrapper.readPayloadAsJAXB(MessageWrapper.java:171)
at com.sun.xml.internal.ws.client.dispatch.JAXBDispatch.toReturnValue(JAXBDispatch.java:88)
at com.sun.xml.internal.ws.client.dispatch.DispatchImpl.doInvoke(DispatchImpl.java:274)
at com.sun.xml.internal.ws.client.dispatch.DispatchImpl.invoke(DispatchImpl.java:289)
at com.goldengate.monitor.jagent.comm.ws.ManagerService.getRegistry(ManagerService.java:267)
at com.goldengate.monitor.jagent.comm.ws.ManagerWSApi.getInstanceInfo(ManagerWSApi.java:230)
Then you thought deleting and creating datastore commands would help, but you got invalid command errors in GGSCI ( cause those commands were already deprecated in the OGG version that you were using)..
