This example shows how to create and configure custom attribute serialization in Titan. Out of the box, Titan handles a limited set of simple types for serialization. Matthias mentioned that previous versions of Titan allowed serialization for almost anything, but that proved to be a maintenance nightmare, especially for collections that contained arbitrary objects.
This HashMapSerializer uses default Java object serialization for the map and its contents. Keep in mind that the format is not optimized for compactness, like the native Titan data types and associated serializers. I recommend using the native Titan data types as much as possible.
mvn clean package
cp ./target/*.jar $TITAN_HOME/lib/
cp -r ./conf/* $TITAN_HOME/conf/
attributes.custom.attribute1.attribute-class=java.lang.StringBuffer
attributes.custom.attribute1.serializer-class=pluradj.titan.graphdb.database.serialize.attribute.StringBufferSerializer
attributes.custom.attribute2.attribute-class=java.util.HashMap
attributes.custom.attribute2.serializer-class=pluradj.titan.graphdb.database.serialize.attribute.HashMapSerializer
[vagrant@localhost titan-1.0.0-hadoop1]$ rm -rf ./db/
[vagrant@localhost titan-1.0.0-hadoop1]$ ./bin/gremlin.sh
\,,,/
(o o)
-----oOOo-(3)-oOOo-----
plugin activated: aurelius.titan
plugin activated: tinkerpop.server
plugin activated: tinkerpop.utilities
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/tmp/titan-1.0.0-hadoop1/lib/slf4j-log4j12-1.7.5.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/tmp/titan-1.0.0-hadoop1/lib/logback-classic-1.1.2.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]
00:11:35 INFO org.apache.tinkerpop.gremlin.hadoop.structure.HadoopGraph - HADOOP_GREMLIN_LIBS is set to: /tmp/titan-1.0.0-hadoop1/lib
plugin activated: tinkerpop.hadoop
plugin activated: tinkerpop.tinkergraph
gremlin> graph = TitanFactory.open('./conf/attr-titan-berkeleyje.properties')
*** StringBufferSerializer constructor
*** HashMapSerializer constructor
==>standardtitangraph[berkeleyje:/tmp/titan-1.0.0-hadoop1/./conf/../db/berkeley]
gremlin> mgmt = graph.openManagement()
==>com.thinkaurelius.titan.graphdb.database.management.ManagementSystem@78010562
gremlin> hello = mgmt.makePropertyKey('hello').dataType(StringBuffer.class).cardinality(Cardinality.SINGLE).make()
==>hello
gremlin> poi = mgmt.makePropertyKey('poi').dataType(HashMap.class).cardinality(Cardinality.SINGLE).make()
==>poi
gremlin> mgmt.commit()
==>null
gremlin> v = graph.addVertex()
==>v[4240]
gremlin> v.property('hello', new StringBuffer('world'))
==>vp[hello->world]
gremlin> m = [] as HashMap
gremlin> m.name = 'rdu'; m.lat = 35.880; m.lon = -78.788; m.col = java.awt.Color.ORANGE
==>java.awt.Color[r=255,g=200,b=0]
gremlin> v.property('poi', m)
==>vp[poi->{col=java.awt.Color[]
gremlin> graph.tx().commit()
*** StringBufferSerializer write
*** HashMapSerializer write
==>null
gremlin> g = graph.traversal()
==>graphtraversalsource[standardtitangraph[berkeleyje:/tmp/titan-1.0.0-hadoop1/./conf/../db/berkeley], standard]
gremlin> vx = g.V().next()
00:13:27 WARN com.thinkaurelius.titan.graphdb.transaction.StandardTitanTx - Query requires iterating over all vertices [()]. For better performance, use indexes
==>v[4240]
gremlin> sb = vx.values('hello').next()
*** StringBufferSerializer read
==>world
gremlin> sb.getClass()
==>class java.lang.StringBuffer
gremlin> hm = vx.values('poi').next()
*** HashMapSerializer read
==>col=java.awt.Color[r=255,g=200,b=0]
==>name=rdu
==>lon=-78.788
==>lat=35.880
gremlin> hm.getClass()
==>class java.util.HashMap
gremlin> col = hm.col
==>java.awt.Color[r=255,g=200,b=0]
gremlin> col.getClass()
==>class java.awt.Color
gremlin> :q
[vagrant@localhost titan-1.0.0-hadoop1]$ ./bin/gremlin-server.sh ./conf/gremlin-server/attr-gremlin-server.yaml
+ '[' ./conf/gremlin-server/attr-gremlin-server.yaml = -i ']'
+ ARGS=./conf/gremlin-server/attr-gremlin-server.yaml
+ '[' 1 = 0 ']'
+ exec /opt/jdk1.8.0_60/bin/java -server -Dtitan.logdir=/tmp/titan-1.0.0-hadoop1/bin/../log -Dlog4j.configuration=conf/gremlin-server/log4j-server.properties -Xms32m -Xmx512m -javaagent:/tmp/titan-1.0.0-hadoop1/lib/jamm-0.3.0.jar -cp <classpath> org.apache.tinkerpop.gremlin.server.GremlinServer ./conf/gremlin-server/attr-gremlin-server.yaml
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/tmp/titan-1.0.0-hadoop1/lib/slf4j-log4j12-1.7.5.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/tmp/titan-1.0.0-hadoop1/lib/logback-classic-1.1.2.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]
0 [main] INFO org.apache.tinkerpop.gremlin.server.GremlinServer -
\,,,/
(o o)
-----oOOo-(3)-oOOo-----
125 [main] INFO org.apache.tinkerpop.gremlin.server.GremlinServer - Configuring Gremlin Server from ./conf/gremlin-server/attr-gremlin-server.yaml
217 [main] INFO org.apache.tinkerpop.gremlin.server.util.MetricManager - Configured Metrics ConsoleReporter configured with report interval=180000ms
219 [main] INFO org.apache.tinkerpop.gremlin.server.util.MetricManager - Configured Metrics CsvReporter configured with report interval=180000ms to fileName=/tmp/gremlin-server-metrics.csv
402 [main] INFO org.apache.tinkerpop.gremlin.server.util.MetricManager - Configured Metrics JmxReporter configured with domain= and agentId=
404 [main] INFO org.apache.tinkerpop.gremlin.server.util.MetricManager - Configured Metrics Slf4jReporter configured with interval=180000ms and loggerName=org.apache.tinkerpop.gremlin.server.Settings$Slf4jReporterMetrics
1094 [main] INFO com.thinkaurelius.titan.graphdb.configuration.GraphDatabaseConfiguration - Generated unique-instance-id=7f0000017043-localhost-localdomain1
1126 [main] INFO com.thinkaurelius.titan.diskstorage.Backend - Initiated backend operations thread pool of size 16
*** StringBufferSerializer constructor
*** HashMapSerializer constructor
1277 [main] INFO com.thinkaurelius.titan.diskstorage.log.kcvs.KCVSLog - Loaded unidentified ReadMarker start time 2015-11-13T05:15:10.557Z into com.thinkaurelius.titan.diskstorage.log.kcvs.KCVSLog$MessagePuller@492691d7
1277 [main] INFO org.apache.tinkerpop.gremlin.server.GremlinServer - Graph [graph] was successfully configured via [./conf/gremlin-server/attr-titan-berkeleyje-server.properties].
1277 [main] INFO org.apache.tinkerpop.gremlin.server.util.ServerGremlinExecutor - Initialized Gremlin thread pool. Threads in pool named with pattern gremlin-*
1706 [main] INFO org.apache.tinkerpop.gremlin.groovy.engine.ScriptEngines - Loaded nashorn ScriptEngine
2184 [main] INFO org.apache.tinkerpop.gremlin.groovy.engine.ScriptEngines - Loaded gremlin-groovy ScriptEngine
2697 [main] INFO org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor - Initialized gremlin-groovy ScriptEngine with scripts/empty-sample.groovy
2697 [main] INFO org.apache.tinkerpop.gremlin.server.util.ServerGremlinExecutor - Initialized GremlinExecutor and configured ScriptEngines.
2704 [main] INFO org.apache.tinkerpop.gremlin.server.util.ServerGremlinExecutor - A GraphTraversalSource is now bound to [g] with graphtraversalsource[standardtitangraph[berkeleyje:./db/berkeley], standard]
2823 [main] INFO org.apache.tinkerpop.gremlin.server.AbstractChannelizer - Configured application/vnd.gremlin-v1.0+gryo with org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0
2824 [main] INFO org.apache.tinkerpop.gremlin.server.AbstractChannelizer - Configured application/vnd.gremlin-v1.0+gryo-stringd with org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0
2949 [main] INFO org.apache.tinkerpop.gremlin.server.AbstractChannelizer - Configured application/vnd.gremlin-v1.0+json with org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerGremlinV1d0
2950 [main] INFO org.apache.tinkerpop.gremlin.server.AbstractChannelizer - Configured application/json with org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV1d0
3064 [gremlin-server-boss-1] INFO org.apache.tinkerpop.gremlin.server.GremlinServer - Gremlin Server configured with worker thread pool of 1, gremlin pool of 8 and boss thread pool of 1.
3064 [gremlin-server-boss-1] INFO org.apache.tinkerpop.gremlin.server.GremlinServer - Channel started at port 8182.
[vagrant@localhost titan-1.0.0-hadoop1]$ ./bin/gremlin.sh
\,,,/
(o o)
-----oOOo-(3)-oOOo-----
plugin activated: aurelius.titan
plugin activated: tinkerpop.server
plugin activated: tinkerpop.utilities
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/tmp/titan-1.0.0-hadoop1/lib/slf4j-log4j12-1.7.5.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/tmp/titan-1.0.0-hadoop1/lib/logback-classic-1.1.2.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]
00:18:24 INFO org.apache.tinkerpop.gremlin.hadoop.structure.HadoopGraph - HADOOP_GREMLIN_LIBS is set to: /tmp/titan-1.0.0-hadoop1/lib
plugin activated: tinkerpop.hadoop
plugin activated: tinkerpop.tinkergraph
gremlin> :remote connect tinkerpop.server ./conf/remote.yaml
==>Connected - localhost/127.0.0.1:8182
gremlin> :> g.V().properties()
==>vp[hello->world]
==>vp[poi->{col=java.awt.Color[]
gremlin> :> g.V().values('poi')
==>{col=java.awt.Color[r=255,g=200,b=0], name=rdu, lon=-78.788, lat=35.880}
gremlin> :> g.V().values('poi').next().col.getGreen()
==>200
gremlin> :remote close
==>Removed - Gremlin Server - [localhost/127.0.0.1:8182]
gremlin> :q
204820 [gremlin-server-worker-1] INFO org.apache.tinkerpop.gremlin.server.op.OpLoader - Adding the standard OpProcessor.
204821 [gremlin-server-worker-1] INFO org.apache.tinkerpop.gremlin.server.op.OpLoader - Adding the control OpProcessor.
204824 [gremlin-server-worker-1] INFO org.apache.tinkerpop.gremlin.server.op.OpLoader - Adding the session OpProcessor.
204903 [gremlin-server-exec-1] WARN com.thinkaurelius.titan.graphdb.transaction.StandardTitanTx - Query requires iterating over all vertices [()]. For better performance, use indexes
*** StringBufferSerializer read
*** HashMapSerializer read
211105 [gremlin-server-exec-2] WARN com.thinkaurelius.titan.graphdb.transaction.StandardTitanTx - Query requires iterating over all vertices [()]. For better performance, use indexes
*** HashMapSerializer read
216459 [gremlin-server-exec-3] WARN com.thinkaurelius.titan.graphdb.transaction.StandardTitanTx - Query requires iterating over all vertices [()]. For better performance, use indexes
*** HashMapSerializer read