I want to load GraphOfTheGodsFactory using cassandra & es. 

It is giving me this exception when i try to do  gremlin> graph = JanusGraphFactory.open('conf/janusgraph-cassandra-es.properties')

java.lang.IllegalArgumentException: Could not instantiate implementation: org.janusgraph.diskstorage.es.ElasticSearchIndex

at org.janusgraph.util.system.ConfigurationUtil.instantiate(ConfigurationUtil.java:69)

at org.janusgraph.diskstorage.Backend.getImplementationClass(Backend.java:480)

at org.janusgraph.diskstorage.Backend.getIndexes(Backend.java:467)

at org.janusgraph.diskstorage.Backend.<init>(Backend.java:154)

at org.janusgraph.graphdb.configuration.GraphDatabaseConfiguration.getBackend(GraphDatabaseConfiguration.java:1840)

at org.janusgraph.graphdb.database.StandardJanusGraph.<init>(StandardJanusGraph.java:134)

at org.janusgraph.core.JanusGraphFactory.open(JanusGraphFactory.java:107)

at org.janusgraph.core.JanusGraphFactory.open(JanusGraphFactory.java:75)

at org.janusgraph.core.JanusGraphFactory$open.call(Unknown Source)

at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)

at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)

at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125)

at groovysh_evaluate.run(groovysh_evaluate:3)

at org.codehaus.groovy.vmplugin.v7.IndyInterface.selectMethod(IndyInterface.java:232)

at org.codehaus.groovy.tools.shell.Interpreter.evaluate(Interpreter.groovy:70)

at org.codehaus.groovy.tools.shell.Groovysh.execute(Groovysh.groovy:190)

at org.apache.tinkerpop.gremlin.console.GremlinGroovysh.super$3$execute(GremlinGroovysh.groovy)

at sun.reflect.GeneratedMethodAccessor14.invoke(Unknown Source)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:498)

at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)

at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)

at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1215)

at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuperN(ScriptBytecodeAdapter.java:132)

at org.apache.tinkerpop.gremlin.console.GremlinGroovysh.execute(GremlinGroovysh.groovy:72)

at org.codehaus.groovy.vmplugin.v7.IndyInterface.selectMethod(IndyInterface.java:232)

at org.codehaus.groovy.tools.shell.Shell.leftShift(Shell.groovy:122)

at org.codehaus.groovy.vmplugin.v7.IndyInterface.selectMethod(IndyInterface.java:232)

at org.codehaus.groovy.tools.shell.ShellRunner.work(ShellRunner.groovy:95)

at org.codehaus.groovy.tools.shell.InteractiveShellRunner.super$2$work(InteractiveShellRunner.groovy)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:498)

at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)

at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)

at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1215)

at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuperN(ScriptBytecodeAdapter.java:132)

at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuper0(ScriptBytecodeAdapter.java:152)

at org.codehaus.groovy.tools.shell.InteractiveShellRunner.work(InteractiveShellRunner.groovy:124)

at org.codehaus.groovy.vmplugin.v7.IndyInterface.selectMethod(IndyInterface.java:232)

at org.codehaus.groovy.tools.shell.ShellRunner.run(ShellRunner.groovy:59)

at org.codehaus.groovy.tools.shell.InteractiveShellRunner.super$2$run(InteractiveShellRunner.groovy)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:498)

at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)

at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)

at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1215)

at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuperN(ScriptBytecodeAdapter.java:132)

at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuper0(ScriptBytecodeAdapter.java:152)

at org.codehaus.groovy.tools.shell.InteractiveShellRunner.run(InteractiveShellRunner.groovy:83)

at org.codehaus.groovy.vmplugin.v7.IndyInterface.selectMethod(IndyInterface.java:232)

at org.apache.tinkerpop.gremlin.console.Console.<init>(Console.groovy:152)

at org.codehaus.groovy.vmplugin.v7.IndyInterface.selectMethod(IndyInterface.java:232)

at org.apache.tinkerpop.gremlin.console.Console.main(Console.groovy:455)

Caused by: java.lang.reflect.InvocationTargetException

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.lang.reflect.Constructor.newInstance(Constructor.java:423)

at org.janusgraph.util.system.ConfigurationUtil.instantiate(ConfigurationUtil.java:58)

... 56 more

Caused by: org.elasticsearch.client.transport.NoNodeAvailableException: None of the configured nodes are available: []

at org.elasticsearch.client.transport.TransportClientNodesService.ensureNodesAreAvailable(TransportClientNodesService.java:279)

at org.elasticsearch.client.transport.TransportClientNodesService.execute(TransportClientNodesService.java:198)

at org.elasticsearch.client.transport.support.InternalTransportClusterAdminClient.execute(InternalTransportClusterAdminClient.java:86)

at org.elasticsearch.client.support.AbstractClusterAdminClient.health(AbstractClusterAdminClient.java:127)

at org.elasticsearch.action.admin.cluster.health.ClusterHealthRequestBuilder.doExecute(ClusterHealthRequestBuilder.java:92)

at org.elasticsearch.action.ActionRequestBuilder.execute(ActionRequestBuilder.java:91)

at org.elasticsearch.action.ActionRequestBuilder.execute(ActionRequestBuilder.java:65)

at org.janusgraph.diskstorage.es.ElasticSearchIndex.<init>(ElasticSearchIndex.java:215)

... 61 more

Any thoughts ?