title: Janus Graph example-remotegraph Error: Unknown external index backend: jgex
body: <p>I work with JanusGraph0.5.3 for some test on windows. I want to use Java client to connect the gremlin-server.
  I launch the server</p>
  <pre><code>gremlin-server.bat
  </code></pre>
  <p>It seems to be successful</p>
  <pre><code>SLF4J: Class path contains multiple SLF4J bindings.
  SLF4J: Found binding in [jar:file:/D:/Users/Lenovo/Downloads/janusgraph-0.5.3/lib/slf4j-log4j12-1.7.12.jar!/org/slf4j/impl/StaticLoggerBinder.class]
  SLF4J: Found binding in [jar:file:/D:/Users/Lenovo/Downloads/janusgraph-0.5.3/lib/logback-classic-1.1.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
  SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
  SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory]
  log4j: Using URL [file:/D:/Users/Lenovo/Downloads/janusgraph-0.5.3/conf/gremlin-server/log4j-server.properties] for automatic log4j configuration.
  log4j: Reading configuration from URL file:/D:/Users/Lenovo/Downloads/janusgraph-0.5.3/conf/gremlin-server/log4j-server.properties
  log4j: Parsing for [root] with value=[INFO, A1, A2].
  log4j: Level token is [INFO].
  log4j: Category root set to INFO
  log4j: Parsing appender named &quot;A1&quot;.
  log4j: Parsing layout options for &quot;A1&quot;.
  log4j: Setting property [conversionPattern] to [%-4r [%t] %-5p %c %x - %m%n].
  log4j: End of parsing for &quot;A1&quot;.
  log4j: Setting property [file] to [D:\Users\Lenovo\Downloads\janusgraph-0.5.3\logs/gremlin-server.log].
  log4j: Setting property [threshold] to [INFO].
  log4j: setFile called: D:\Users\Lenovo\Downloads\janusgraph-0.5.3\logs/gremlin-server.log, true
  log4j: setFile ended
  log4j: Parsed &quot;A1&quot; options.
  log4j: Parsing appender named &quot;A2&quot;.
  log4j: Parsing layout options for &quot;A2&quot;.
  log4j: Setting property [conversionPattern] to [%-4r [%t] %-5p %c %x - %m%n].
  log4j: End of parsing for &quot;A2&quot;.
  log4j: Setting property [threshold] to [INFO].
  log4j: Parsed &quot;A2&quot; options.
  log4j: Finished configuring.
  0    [main] INFO  com.jcabi.manifests.Manifests  - 113 attributes loaded from 263 stream(s) in 98ms, 113 saved, 3649 ignored: [&quot;Agent-Class&quot;, &quot;Ant-Version&quot;, &quot;Archiver-Version&quot;, &quot;Automatic-Module-Name&quot;, &quot;Bnd-LastModified&quot;, &quot;Boot-Class-Path&quot;, &quot;Branch&quot;, &quot;Build-Date&quot;, &quot;Build-Host&quot;, &quot;Build-Id&quot;, &quot;Build-Java-Version&quot;, &quot;Build-Jdk&quot;, &quot;Build-Jdk-Spec&quot;, &quot;Build-Job&quot;, &quot;Build-Number&quot;, &quot;Build-Timestamp&quot;, &quot;Build-Version&quot;, &quot;Built-At&quot;, &quot;Built-By&quot;, &quot;Built-Date&quot;, &quot;Built-OS&quot;, &quot;Built-On&quot;, &quot;Built-Status&quot;, &quot;Bundle-ActivationPolicy&quot;, &quot;Bundle-Activator&quot;, &quot;Bundle-BuddyPolicy&quot;, &quot;Bundle-Category&quot;, &quot;Bundle-ClassPath&quot;, &quot;Bundle-ContactAddress&quot;, &quot;Bundle-Description&quot;, &quot;Bundle-DocURL&quot;, &quot;Bundle-License&quot;, &quot;Bundle-ManifestVersion&quot;, &quot;Bundle-Name&quot;, &quot;Bundle-NativeCode&quot;, &quot;Bundle-RequiredExecutionEnvironment&quot;, &quot;Bundle-SymbolicName&quot;, &quot;Bundle-Vendor&quot;, &quot;Bundle-Version&quot;, &quot;Can-Redefine-Classes&quot;, &quot;Change&quot;, &quot;Class-Path&quot;, &quot;Copyright&quot;, &quot;Created-By&quot;, &quot;DSTAMP&quot;, &quot;DynamicImport-Package&quot;, &quot;Eclipse-BuddyPolicy&quot;, &quot;Eclipse-ExtensibleAPI&quot;, &quot;Embed-Dependency&quot;, &quot;Embed-Transitive&quot;, &quot;Export-Package&quot;, &quot;Extension-Name&quot;, &quot;Extension-name&quot;, &quot;Fragment-Host&quot;, &quot;Gradle-Version&quot;, &quot;Gremlin-Lib-Paths&quot;, &quot;Gremlin-Plugin-Dependencies&quot;, &quot;Gremlin-Plugin-Paths&quot;, &quot;Ignore-Package&quot;, &quot;Implementation-Build&quot;, &quot;Implementation-Build-Date&quot;, &quot;Implementation-Title&quot;, &quot;Implementation-URL&quot;, &quot;Implementation-Vendor&quot;, &quot;Implementation-Vendor-Id&quot;, &quot;Implementation-Version&quot;, &quot;Import-Package&quot;, &quot;Include-Resource&quot;, &quot;JCabi-Build&quot;, &quot;JCabi-Date&quot;, &quot;JCabi-Version&quot;, &quot;Java-Vendor&quot;, &quot;Java-Version&quot;, &quot;Main-Class&quot;, &quot;Manifest-Version&quot;, &quot;Maven-Version&quot;, &quot;Module-Email&quot;, &quot;Module-Origin&quot;, &quot;Module-Owner&quot;, &quot;Module-Source&quot;, &quot;Multi-Release&quot;, &quot;Originally-Created-By&quot;, &quot;Os-Arch&quot;, &quot;Os-Name&quot;, &quot;Os-Version&quot;, &quot;Package&quot;, &quot;Premain-Class&quot;, &quot;Private-Package&quot;, &quot;Provide-Capability&quot;, &quot;Require-Bundle&quot;, &quot;Require-Capability&quot;, &quot;Scm-Connection&quot;, &quot;Scm-Revision&quot;, &quot;Scm-Url&quot;, &quot;Specification-Title&quot;, &quot;Specification-Vendor&quot;, &quot;Specification-Version&quot;, &quot;TODAY&quot;, &quot;TSTAMP&quot;, &quot;Time-Zone-Database-Version&quot;, &quot;Tool&quot;, &quot;X-Compile-Elasticsearch-Snapshot&quot;, &quot;X-Compile-Elasticsearch-Version&quot;, &quot;X-Compile-Lucene-Version&quot;, &quot;X-Compile-Source-JDK&quot;, &quot;X-Compile-Target-JDK&quot;, &quot;hash&quot;, &quot;implementation-version&quot;, &quot;mode&quot;, &quot;package&quot;, &quot;service&quot;, &quot;url&quot;, &quot;version&quot;]
  1    [main] INFO  org.apache.tinkerpop.gremlin.server.GremlinServer  - 3.4.6
           \,,,/
           (o o)
  -----oOOo-(3)-oOOo-----
  
  81   [main] INFO  org.apache.tinkerpop.gremlin.server.GremlinServer  - Configuring Gremlin Server from D:\Users\Lenovo\Downloads\janusgraph-0.5.3\conf\gremlin-server\gremlin-server.yaml
  122  [main] INFO  org.apache.tinkerpop.gremlin.server.util.MetricManager  - Configured Metrics ConsoleReporter configured with report interval=180000ms
  123  [main] INFO  org.apache.tinkerpop.gremlin.server.util.MetricManager  - Configured Metrics CsvReporter configured with report interval=180000ms to fileName=/tmp/gremlin-server-metrics.csv
  160  [main] INFO  org.apache.tinkerpop.gremlin.server.util.MetricManager  - Configured Metrics JmxReporter configured with domain= and agentId=
  161  [main] INFO  org.apache.tinkerpop.gremlin.server.util.MetricManager  - Configured Metrics Slf4jReporter configured with interval=180000ms and loggerName=org.apache.tinkerpop.gremlin.server.Settings$Slf4jReporterMetrics
  610  [main] INFO  org.janusgraph.diskstorage.configuration.builder.ReadConfigurationBuilder  - Set default timestamp provider MICRO
  618  [main] INFO  org.janusgraph.graphdb.idmanagement.UniqueInstanceIdRetriever  - Generated unique-instance-id=c0a8110121912-DESKTOP-P5265PE1
  627  [main] INFO  org.janusgraph.diskstorage.Backend  - Initiated backend operations thread pool of size 32
  678  [main] INFO  org.janusgraph.diskstorage.log.kcvs.KCVSLog  - Loaded unidentified ReadMarker start time 2021-01-25T01:28:22.797Z into org.janusgraph.diskstorage.log.kcvs.KCVSLog$MessagePuller@4e70a728
  679  [main] INFO  org.apache.tinkerpop.gremlin.server.GremlinServer  - Graph [graph] was successfully configured via [conf/janusgraph-inmemory.properties].
  679  [main] INFO  org.apache.tinkerpop.gremlin.server.util.ServerGremlinExecutor  - Initialized Gremlin thread pool.  Threads in pool named with pattern gremlin-*
  712  [main] INFO  org.apache.tinkerpop.gremlin.server.util.ServerGremlinExecutor  - Initialized GremlinExecutor and preparing GremlinScriptEngines instances.
  2658 [main] INFO  org.apache.tinkerpop.gremlin.server.util.ServerGremlinExecutor  - Initialized gremlin-groovy GremlinScriptEngine and registered metrics
  2660 [main] INFO  org.apache.tinkerpop.gremlin.server.util.ServerGremlinExecutor  - A GraphTraversalSource is now bound to [g] with graphtraversalsource[standardjanusgraph[inmemory:[127.0.0.1]], standard]
  2672 [main] INFO  org.apache.tinkerpop.gremlin.server.op.OpLoader  - Adding the standard OpProcessor.
  2674 [main] INFO  org.apache.tinkerpop.gremlin.server.op.OpLoader  - Adding the session OpProcessor.
  2729 [main] INFO  org.apache.tinkerpop.gremlin.server.op.OpLoader  - Adding the traversal OpProcessor.
  2735 [main] INFO  org.apache.tinkerpop.gremlin.server.op.traversal.TraversalOpProcessor  - Initialized cache for TraversalOpProcessor with size 1000 and expiration time of 600000 ms
  2809 [main] INFO  org.apache.tinkerpop.gremlin.server.GremlinServer  - Executing start up LifeCycleHook
  2818 [main] INFO  org.apache.tinkerpop.gremlin.server.GremlinServer  - Executed once at startup of Gremlin Server.
  2822 [main] INFO  org.apache.tinkerpop.gremlin.server.GremlinServer  - idleConnectionTimeout was set to 0 which resolves to 0 seconds when configuring this value - this feature will be disabled
  2823 [main] INFO  org.apache.tinkerpop.gremlin.server.GremlinServer  - keepAliveInterval was set to 0 which resolves to 0 seconds when configuring this value - this feature will be disabled
  2825 [main] WARN  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - The org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0 serialization class is deprecated.
  2861 [main] INFO  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - Configured application/vnd.gremlin-v3.0+gryo with org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0
  2862 [main] WARN  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - The org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0 serialization class is deprecated.
  2864 [main] INFO  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - Configured application/vnd.gremlin-v3.0+gryo-stringd with org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0
  2880 [main] INFO  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - Configured application/vnd.gremlin-v3.0+json with org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV3d0
  2880 [main] INFO  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - Configured application/json with org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV3d0
  2882 [main] WARN  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - The org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0 serialization class is deprecated.
  2882 [main] INFO  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - Configured application/vnd.gremlin-v1.0+gryo with org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0
  2883 [main] WARN  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - The org.apache.tinkerpop.gremlin.driver.ser.GryoLiteMessageSerializerV1d0 serialization class is deprecated.
  2884 [main] INFO  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - Configured application/vnd.gremlin-v1.0+gryo-lite with org.apache.tinkerpop.gremlin.driver.ser.GryoLiteMessageSerializerV1d0
  2884 [main] WARN  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - The org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0 serialization class is deprecated.
  2884 [main] INFO  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - Configured application/vnd.gremlin-v1.0+gryo-stringd with org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0
  2887 [main] INFO  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - Configured application/vnd.gremlin-v2.0+json with org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV2d0
  2887 [main] INFO  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - application/json already has org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV3d0 configured - it will not be replaced by org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV2d0, change order of serialization configuration if this is not desired.
  2891 [main] INFO  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - Configured application/vnd.gremlin-v1.0+json with org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerGremlinV1d0
  2892 [main] INFO  org.apache.tinkerpop.gremlin.server.AbstractChannelizer  - application/json already has org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV3d0 configured - it will not be replaced by org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV1d0, change order of serialization configuration if this is not desired.
  3198 [gremlin-server-boss-1] INFO  org.apache.tinkerpop.gremlin.server.GremlinServer  - Gremlin Server configured with worker thread pool of 1, gremlin pool of 16 and boss thread pool of 1.
  3198 [gremlin-server-boss-1] INFO  org.apache.tinkerpop.gremlin.server.GremlinServer  - Channel started at port 8182.
  </code></pre>
  <p>However, when I execute the example-remotegraph</p>
  <pre><code>mvn clean install
  mvn exec:java -pl :example-remotegraph
  </code></pre>
  <p>I got an exception.  <code>Unknown external index backend: jgex</code></p>
  <pre><code>[INFO] Scanning for projects...
  [INFO]
  [INFO] -----------------&lt; org.janusgraph:example-remotegraph &gt;-----------------
  [INFO] Building Example-RemoteGraph: Example with RemoteGraph 0.5.3
  [INFO] --------------------------------[ jar ]---------------------------------
  [INFO]
  [INFO] --- exec-maven-plugin:1.6.0:java (default-cli) @ example-remotegraph ---
  0    [org.janusgraph.example.RemoteGraphApp.main()] INFO  org.janusgraph.example.RemoteGraphApp  - opening graph
  542  [org.janusgraph.example.RemoteGraphApp.main()] INFO  org.janusgraph.example.RemoteGraphApp  - creating schema
  972  [org.janusgraph.example.RemoteGraphApp.main()] INFO  org.apache.tinkerpop.gremlin.driver.Connection  - Created new connection for ws://127.0.0.1:8182/gremlin
  977  [org.janusgraph.example.RemoteGraphApp.main()] INFO  org.apache.tinkerpop.gremlin.driver.Connection  - Created new connection for ws://127.0.0.1:8182/gremlin
  978  [org.janusgraph.example.RemoteGraphApp.main()] INFO  org.apache.tinkerpop.gremlin.driver.ConnectionPool  - Opening connection pool on Host{address=127.0.0.1/127.0.0.1:8182, hostUri=ws://127.0.0.1:8182/gremlin} with core size of 2
  1270 [org.janusgraph.example.RemoteGraphApp.main()] ERROR org.janusgraph.example.GraphApp  - org.apache.tinkerpop.gremlin.driver.exception.ResponseException: Unknown external index backend: jgex
  java.util.concurrent.CompletionException: org.apache.tinkerpop.gremlin.driver.exception.ResponseException: Unknown external index backend: jgex
          at java.util.concurrent.CompletableFuture.reportJoin(CompletableFuture.java:375)
          at java.util.concurrent.CompletableFuture.join(CompletableFuture.java:1947)
          at org.apache.tinkerpop.gremlin.driver.ResultSet.one(ResultSet.java:119)
          at org.apache.tinkerpop.gremlin.driver.ResultSet$1.hasNext(ResultSet.java:171)
          at java.util.Iterator.forEachRemaining(Iterator.java:115)
          at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
          at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:482)
          at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:472)
          at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
          at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
          at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
          at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418)
          at org.janusgraph.example.RemoteGraphApp.createSchema(RemoteGraphApp.java:188)
          at org.janusgraph.example.GraphApp.runApp(GraphApp.java:294)
          at org.janusgraph.example.RemoteGraphApp.main(RemoteGraphApp.java:194)
          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.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:282)
          at java.lang.Thread.run(Thread.java:748)
  </code></pre>
  <p>I think I followed the guide correctly, how to solve it?</p>