i have modified the java gateway to check jboss7 via JMX (only changed the connection string in JMXItemChecker.java and added libraries).
it works fine, but if 1 jboss (out of many) is unresponsive, i´m getting following alert (after some time):
2013-06-05 07:53:38.156 [pool-1-thread-29] WARN com.zabbix.gateway.SocketProcessor - error processing request
com.zabbix.gateway.ZabbixException: java.net.MalformedURLException: Unsupported protocol: remoting-jmx
at com.zabbix.gateway.JMXItemChecker.getValues(JMXItemChecker.java:100) ~[zabbix-java-gateway-2.0.3.jar:na]
at com.zabbix.gateway.SocketProcessor.run(SocketProcessor.java:63) ~[zabbix-java-gateway-2.0.3.jar:na]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) [na:1.7.0_05]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) [na:1.7.0_05]
at java.lang.Thread.run(Thread.java:722) [na:1.7.0_05]
Caused by: java.net.MalformedURLException: Unsupported protocol: remoting-jmx
at javax.management.remote.JMXConnectorFactory.newJMXConnector(JMXConnectorFactory.java:356) ~[na:1.7.0_05]
at javax.management.remote.JMXConnectorFactory.connect(JMXConnectorFactory.java:266) ~[na:1.7.0_05]
at com.zabbix.gateway.JMXItemChecker.getValues(JMXItemChecker.java:92) ~[zabbix-java-gateway-2.0.3.jar:na]
... 4 common frames omitted
Caused by: java.io.IOException: Too many open files
at sun.nio.ch.IOUtil.makePipe(Native Method) ~[na:1.7.0_05]
at sun.nio.ch.EPollSelectorImpl.<init>(EPollSelectorImpl.java:65) ~[na:1.7.0_05]
at sun.nio.ch.EPollSelectorProvider.openSelector(EPollSelectorProvider.java:36) ~[na:1.7.0_05]
at java.nio.channels.Selector.open(Selector.java:227) ~[na:1.7.0_05]
at org.xnio.nio.NioXnioWorker.<init>(NioXnioWorker.java:112) ~[xnio-nio-3.0.3.GA.jar:3.0.3.GA]
at org.xnio.nio.NioXnio.createWorker(NioXnio.java:126) ~[xnio-nio-3.0.3.GA.jar:3.0.3.GA]
at org.jboss.remoting3.EndpointImpl.construct(EndpointImpl.java:137) ~[jboss-remoting-3.2.3.GA.jar:3.2.3.GA]
at org.jboss.remoting3.Remoting.createEndpoint(Remoting.java:60) ~[jboss-remoting-3.2.3.GA.jar:3.2.3.GA]
at org.jboss.remotingjmx.RemotingConnector.<init>(RemotingConnector.java:89) ~[remoting-jmx-1.0.2.Final.jar:1.0.2.Final]
at org.jboss.remotingjmx.RemotingConnectorProvider.newJMXConnector(RemotingConnectorProvider.java:48) ~[remoting-jmx-1.0.2.Final.jar:1.0.2.Final]
at javax.management.remote.JMXConnectorFactory.getConnectorAsService(JMXConnectorFactory.java:455) ~[na:1.7.0_05]
at javax.management.remote.JMXConnectorFactory.newJMXConnector(JMXConnectorFactory.java:340) ~[na:1.7.0_05]
... 6 common frames omitted

to make it working i have added following libraries to the "lib" directory:
jboss-logging-3.1.0.GA.jar
jboss-marshalling-1.3.11.GA.jar
jboss-marshalling-river-1.3.11.GA.jar
jboss-remoting-3.2.3.GA.jar
jboss-sasl-1.0.0.Final.jar
remoting-jmx-1.0.2.Final.jar
xnio-api-3.0.3.GA.jar
xnio-nio-3.0.3.GA.jar

my workaround is to restart the gateway every 30 mins.

if i have the same situation with the original gateway (1 host down), i´m getting a connection refused error, but that´s all.