Scripts can be sent as URL-encoded In this example, the graph has been autoindexed by Neo4j, so we can look up the name property on nodes.

Raw script source

g.idx('node_auto_index')[[name:'I']]._().out()

Figure 18.44. Final Graph

Example request

script=g.idx%28%27node_auto_index%27%29%5B%5Bname%3A%27I%27%5D%5D._%28%29.out%28%29

Example response

[ {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/1/relationships/out",
  "data" : {
    "name" : "you"
  },
  "traverse" : "http://localhost:7474/db/data/node/1/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/1/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/1/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/1",
  "properties" : "http://localhost:7474/db/data/node/1/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/1/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/1/relationships/in",
  "extensions" : {
  },
  "create_relationship" : "http://localhost:7474/db/data/node/1/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/1/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/1/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/1/relationships/in/{-list|&|types}"
} ]

Import a graph form a GraphML file can be achieved through the Gremlin GraphMLReader. The following script imports a small GraphML file from an URL into Neo4j, resulting in the depicted graph. It then returns a list of all nodes in the graph.

Raw script source

g.loadGraphML('https://raw.github.com/neo4j/gremlin-plugin/master/src/data/graphml1.xml')
g.V

Figure 18.45. Final Graph

Example request

{"script": "g.loadGraphML('https://raw.github.com/neo4j/gremlin-plugin/master/src/data/graphml1.xml');g.V;","params": {}},

Example response

[ {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/5/relationships/out",
  "data" : {
    "name" : "I"
  },
  "traverse" : "http://localhost:7474/db/data/node/5/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/5/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/5/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/5",
  "properties" : "http://localhost:7474/db/data/node/5/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/5/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/5/relationships/in",
  "extensions" : {
  },
  "create_relationship" : "http://localhost:7474/db/data/node/5/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/5/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/5/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/5/relationships/in/{-list|&|types}"
}, {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/6/relationships/out",
  "data" : {
    "name" : "you"
  },
  "traverse" : "http://localhost:7474/db/data/node/6/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/6/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/6/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/6",
  "properties" : "http://localhost:7474/db/data/node/6/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/6/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/6/relationships/in",
  "extensions" : {
  },
  "create_relationship" : "http://localhost:7474/db/data/node/6/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/6/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/6/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/6/relationships/in/{-list|&|types}"
}, {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/7/relationships/out",
  "data" : {
    "name" : "him"
  },
  "traverse" : "http://localhost:7474/db/data/node/7/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/7/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/7/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/7",
  "properties" : "http://localhost:7474/db/data/node/7/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/7/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/7/relationships/in",
  "extensions" : {
  },
  "create_relationship" : "http://localhost:7474/db/data/node/7/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/7/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/7/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/7/relationships/in/{-list|&|types}"
} ]

The following script returns a sorted list of all nodes connected via outgoing relationships to node 1, sorted by their name-property.

Raw script source

g.idx('node_auto_index').get('name','I').toList()._().out().sort{it.name}.toList()

Figure 18.46. Final Graph

Example request

{"script": "g.idx('node_auto_index').get('name','I').toList()._().out().sort{it.name}.toList()","params": {}},

Example response

[ {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/12/relationships/out",
  "data" : {
    "name" : "him"
  },
  "traverse" : "http://localhost:7474/db/data/node/12/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/12/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/12/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/12",
  "properties" : "http://localhost:7474/db/data/node/12/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/12/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/12/relationships/in",
  "extensions" : {
  },
  "create_relationship" : "http://localhost:7474/db/data/node/12/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/12/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/12/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/12/relationships/in/{-list|&|types}"
}, {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/11/relationships/out",
  "data" : {
    "name" : "you"
  },
  "traverse" : "http://localhost:7474/db/data/node/11/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/11/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/11/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/11",
  "properties" : "http://localhost:7474/db/data/node/11/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/11/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/11/relationships/in",
  "extensions" : {
  },
  "create_relationship" : "http://localhost:7474/db/data/node/11/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/11/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/11/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/11/relationships/in/{-list|&|types}"
} ]

To send a Script JSON encoded, set the payload Content-Type Header. In this example, find all the things that my friends like, and return a table listing my friends by their name, and the names of the things they like in a table with two columns, ignoring the third named step variable I. Remember that everything in Gremlin is an iterator - in order to populate the result table t, iterate through the pipes with >> -1.

Raw script source

i = g.v(%I%)
t= new Table()
i.as('I').out('know').as('friend').out('like').as('likes').table(t,['friend','likes']){it.name}{it.name} >> -1
t

Figure 18.47. Final Graph

Example request

{"script": "i = g.v(19);t= new Table();i.as('I').out('know').as('friend').out('like').as('likes').table(t,['friend','likes']){it.name}{it.name} >> -1;t;","params": {}},

Example response

{
  "data" : [ [ "Joe", "cats" ], [ "Joe", "dogs" ] ],
  "columns" : [ "friend", "likes" ]
}

To set variables in the bindings for the Gremlin Script Engine on the server, you can include a params parameter with a String representing a JSON map of variables to set to initial values. These can then be accessed as normal variables within the script.

Raw script source

meaning_of_life

Figure 18.48. Final Graph

Example request

{
  "script":"meaning_of_life",
  "params":{
    "meaning_of_life" : 42.0
  }
}

Example response

42.0

Send a Gremlin Script, as JSON payload and additional parameters

Raw script source

g.v(me).out

Figure 18.49. Final Graph

Example request

{"script": "g.v(me).out","params": {"me":"4"}},

Example response

[ {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/3/relationships/out",
  "data" : {
    "name" : "you"
  },
  "traverse" : "http://localhost:7474/db/data/node/3/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/3/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/3/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/3",
  "properties" : "http://localhost:7474/db/data/node/3/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/3/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/3/relationships/in",
  "extensions" : {
  },
  "create_relationship" : "http://localhost:7474/db/data/node/3/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/3/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/3/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/3/relationships/in/{-list|&|types}"
} ]

The following script returns a sorted list of all nodes connected via outgoing relationships to node 1, sorted by their name-property.

Raw script source

g.v(%I%).out.name.paths

Figure 18.50. Final Graph

Example request

{"script": "g.v(16).out.name.paths","params": {}},

Example response

[ "[v[16], v[14], you]", "[v[16], v[15], him]" ]

This example demonstrates that you via the Groovy runtime embedded with the server have full access to all of the servers Java APIs. The below example creates Nodes in the database both via the Blueprints and the Neo4j API indexes the nodes via the native Neo4j Indexing API constructs a custom Lucene sorting and searching returns a Neo4j IndexHits result iterator.

Raw script source

import org.neo4j.graphdb.index.*
import org.neo4j.index.lucene.*
import org.apache.lucene.search.*
neo4j = g.getRawGraph()
tx = neo4j.beginTx()
meVertex = g.addVertex([name:'me'])
meNode = meVertex.getRawVertex()
youNode = neo4j.createNode()
youNode.setProperty('name','you')
idxManager = neo4j.index()
personIndex = idxManager.forNodes('persons')
personIndex.add(meNode,'name',meVertex.name)
personIndex.add(youNode,'name',youNode.getProperty('name'))
tx.success()
tx.finish()
query = new QueryContext( 'name:*' ).sort( new Sort(new SortField( 'name',SortField.STRING, true ) ) )
results = personIndex.query( query )

Figure 18.51. Final Graph

Example request

{"script": "import org.neo4j.graphdb.index.*;import org.neo4j.index.lucene.*;import org.apache.lucene.search.*;neo4j = g.getRawGraph();tx = neo4j.beginTx();meVertex = g.addVertex([name:'me']);meNode = meVertex.getRawVertex();youNode = neo4j.createNode();youNode.setProperty('name','you');idxManager = neo4j.index();personIndex = idxManager.forNodes('persons');personIndex.add(meNode,'name',meVertex.name);personIndex.add(youNode,'name',youNode.getProperty('name'));tx.success();tx.finish();query = new QueryContext( 'name:*' ).sort( new Sort(new SortField( 'name',SortField.STRING, true ) ) );results = personIndex.query( query );","params": {}},

Example response

[ {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/26/relationships/out",
  "data" : {
    "name" : "you"
  },
  "traverse" : "http://localhost:7474/db/data/node/26/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/26/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/26/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/26",
  "properties" : "http://localhost:7474/db/data/node/26/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/26/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/26/relationships/in",
  "extensions" : {
  },
  "create_relationship" : "http://localhost:7474/db/data/node/26/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/26/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/26/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/26/relationships/in/{-list|&|types}"
}, {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/25/relationships/out",
  "data" : {
    "name" : "me"
  },
  "traverse" : "http://localhost:7474/db/data/node/25/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/25/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/25/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/25",
  "properties" : "http://localhost:7474/db/data/node/25/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/25/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/25/relationships/in",
  "extensions" : {
  },
  "create_relationship" : "http://localhost:7474/db/data/node/25/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/25/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/25/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/25/relationships/in/{-list|&|types}"
} ]

Exporting a graph can be done by simple emitting the appropriate String.

Raw script source

writer = new GraphMLWriter(g)
out = new java.io.ByteArrayOutputStream()
writer.outputGraph(out)
result = out.toString()

Figure 18.52. Final Graph

Example request

{"script": "writer = new GraphMLWriter(g);out = new java.io.ByteArrayOutputStream();writer.outputGraph(out);result = out.toString();","params": {}},

Example response

"<?xml version=\"1.0\" ?><graphml xmlns=\"http://graphml.graphdrawing.org/xmlns\"><key id=\"name\" for=\"node\" attr.name=\"name\" attr.type=\"string\"></key><graph id=\"G\" edgedefault=\"directed\"><node id=\"8\"><data key=\"name\">you</data></node><node id=\"9\"><data key=\"name\">him</data></node><node id=\"10\"><data key=\"name\">I</data></node><edge id=\"4\" source=\"10\" target=\"8\" label=\"know\"></edge><edge id=\"5\" source=\"10\" target=\"9\" label=\"know\"></edge></graph></graphml>"

Imagine a user being part of different groups. A group can have different roles, and a user can be part of different groups. He also can have different roles in different groups apart from the membership. The association of a User, a Group and a Role can be referred to as a HyperEdge. However, it can be easily modeled in a property graph as a node that captures this n-ary relationship, as depicted below in the U1G2R1 node.

To find out in what roles a user is for a particular groups (here Group2), the following script can traverse this HyperEdge node and provide answers.

Raw script source

g.v(%User1%).out('hasRoleInGroup').as('hyperedge').out('hasGroup').filter{it.name=='Group2'}.back('hyperedge').out('hasRole').name

Figure 18.53. Final Graph

Example request

{"script": "g.v(33).out('hasRoleInGroup').as('hyperedge').out('hasGroup').filter{it.name=='Group2'}.back('hyperedge').out('hasRole').name","params": {}},

Example response

[ "Role1" ]

This example is showing a group count in Germlin, for instance the counting of the different relationship types connected to some the start node. The result is collected into a variable that then is returned.

Raw script source

m = [:]
g.v(%Peter%).bothE().label.groupCount(m) >> -1
m

Figure 18.54. Final Graph

Example request

{"script": "m = [:];g.v(37).bothE().label.groupCount(m) >> -1;m","params": {}},

Example response

"{knows=2, likes=1}"

Multiple traversals can be combined into a single result, using splitting and merging pipes in a lazy fashion.

Raw script source

g.idx('node_auto_index')[['name':'Peter']].copySplit(_().out('knows'), _().in('likes')).fairMerge.name

Figure 18.55. Final Graph

Example request

{"script": "g.idx('node_auto_index')[['name':'Peter']].copySplit(_().out('knows'), _().in('likes')).fairMerge.name","params": {}},

Example response

[ "Ian", "Marie" ]

This example demonstrates basic collaborative filtering - ordering a traversal after occurence counts and substracting objects that are not interesting in the final result.

Here, we are finding Friends-of-Friends that are not Joes friends already. The same can be applied to graphs of users that LIKE things and others.

Raw script source

x=[]
fof=[:]
g.v(%Joe%).out('knows').aggregate(x).out('knows').except(x).groupCount(fof)>>-1
fof.sort{a,b -> b.value <=> a.value}

Figure 18.56. Final Graph

Example request

{"script": "x=[];fof=[:];g.v(53).out('knows').aggregate(x).out('knows').except(x).groupCount(fof)>>-1;fof.sort{a,b -> b.value <=> a.value}","params": {}},

Example response

"{v[51]=2, v[50]=1, v[52]=1}"

Raw script source

 g.v(%George%).outE[[label:'knows']].inV.filter{ it.name == 'Sara'}.drop(0).take(100)._()

Figure 18.57. Final Graph

Example request

{"script": " g.v(47).outE[[label:'knows']].inV.filter{ it.name == 'Sara'}.drop(0).take(100)._()","params": {}},

Example response

[ {
  "outgoing_relationships" : "http://localhost:7474/db/data/node/45/relationships/out",
  "data" : {
    "name" : "Sara"
  },
  "traverse" : "http://localhost:7474/db/data/node/45/traverse/{returnType}",
  "all_typed_relationships" : "http://localhost:7474/db/data/node/45/relationships/all/{-list|&|types}",
  "property" : "http://localhost:7474/db/data/node/45/properties/{key}",
  "self" : "http://localhost:7474/db/data/node/45",
  "properties" : "http://localhost:7474/db/data/node/45/properties",
  "outgoing_typed_relationships" : "http://localhost:7474/db/data/node/45/relationships/out/{-list|&|types}",
  "incoming_relationships" : "http://localhost:7474/db/data/node/45/relationships/in",
  "extensions" : {
  },
  "create_relationship" : "http://localhost:7474/db/data/node/45/relationships",
  "paged_traverse" : "http://localhost:7474/db/data/node/45/paged/traverse/{returnType}{?pageSize,leaseTime}",
  "all_relationships" : "http://localhost:7474/db/data/node/45/relationships/all",
  "incoming_typed_relationships" : "http://localhost:7474/db/data/node/45/relationships/in/{-list|&|types}"
} ]

This example is showing a group count in Germlin, for instance the counting of the different relationship types connected to some the start node. The result is collected into a variable that then is returned.

Raw script source

g.v(%Peter%).bothE()each{g.removeEdge(it)
}

Figure 18.58. Final Graph

Example request

{"script": "g.v(40).bothE()each{g.removeEdge(it);};","params": {}},

Example response

[ ]