Streaming GraphSON

console.txt

Type: LinkedHashMap Value: {id=1, label=person, name=[marko], age=[29]}
Type: LinkedHashMap Value: {id=2, label=person, name=[vadas], age=[27]}
Type: LinkedHashMap Value: {id=3, label=software, name=[lop], lang=[java]}
Type: LinkedHashMap Value: {id=4, label=person, name=[josh], age=[32]}
Type: LinkedHashMap Value: {id=5, label=software, name=[ripple], lang=[java]}
Type: LinkedHashMap Value: {id=6, label=person, name=[peter], age=[35]}

query-output.json

[
    {
        "@type": "g:Map",
        "@value": [
            {
                "@type": "g:T",
                "@value": "id"
            },
            {
                "@type": "g:Int32",
                "@value": 1
            },
            {
                "@type": "g:T",
                "@value": "label"
            },
            "person",
            "name",
            {
                "@type": "g:List",
                "@value": [
                    "marko"
                ]
            },
            "age",
            {
                "@type": "g:List",
                "@value": [
                    {
                        "@type": "g:Int32",
                        "@value": 29
                    }
                ]
            }
        ]
    },
    {
        "@type": "g:Map",
        "@value": [
            {
                "@type": "g:T",
                "@value": "id"
            },
            {
                "@type": "g:Int32",
                "@value": 2
            },
            {
                "@type": "g:T",
                "@value": "label"
            },
            "person",
            "name",
            {
                "@type": "g:List",
                "@value": [
                    "vadas"
                ]
            },
            "age",
            {
                "@type": "g:List",
                "@value": [
                    {
                        "@type": "g:Int32",
                        "@value": 27
                    }
                ]
            }
        ]
    },
    {
        "@type": "g:Map",
        "@value": [
            {
                "@type": "g:T",
                "@value": "id"
            },
            {
                "@type": "g:Int32",
                "@value": 3
            },
            {
                "@type": "g:T",
                "@value": "label"
            },
            "software",
            "name",
            {
                "@type": "g:List",
                "@value": [
                    "lop"
                ]
            },
            "lang",
            {
                "@type": "g:List",
                "@value": [
                    "java"
                ]
            }
        ]
    },
    {
        "@type": "g:Map",
        "@value": [
            {
                "@type": "g:T",
                "@value": "id"
            },
            {
                "@type": "g:Int32",
                "@value": 4
            },
            {
                "@type": "g:T",
                "@value": "label"
            },
            "person",
            "name",
            {
                "@type": "g:List",
                "@value": [
                    "josh"
                ]
            },
            "age",
            {
                "@type": "g:List",
                "@value": [
                    {
                        "@type": "g:Int32",
                        "@value": 32
                    }
                ]
            }
        ]
    },
    {
        "@type": "g:Map",
        "@value": [
            {
                "@type": "g:T",
                "@value": "id"
            },
            {
                "@type": "g:Int32",
                "@value": 5
            },
            {
                "@type": "g:T",
                "@value": "label"
            },
            "software",
            "name",
            {
                "@type": "g:List",
                "@value": [
                    "ripple"
                ]
            },
            "lang",
            {
                "@type": "g:List",
                "@value": [
                    "java"
                ]
            }
        ]
    },
    {
        "@type": "g:Map",
        "@value": [
            {
                "@type": "g:T",
                "@value": "id"
            },
            {
                "@type": "g:Int32",
                "@value": 6
            },
            {
                "@type": "g:T",
                "@value": "label"
            },
            "person",
            "name",
            {
                "@type": "g:List",
                "@value": [
                    "peter"
                ]
            },
            "age",
            {
                "@type": "g:List",
                "@value": [
                    {
                        "@type": "g:Int32",
                        "@value": 35
                    }
                ]
            }
        ]
    }
]

stream-results.java

final GraphTraversalSource g = TinkerFactory.createModern().traversal();

// set up streaming to use the GraphSON3 codec 
final JsonFactory jsonFactory = new MappingJsonFactory(GraphSONMapper.build().
        addRegistry(TinkerIoRegistryV3.instance()).version(GraphSONVersion.V3_0).create().createMapper());

// used a local file but could use a S3 OutputStream
final JsonGenerator jsonGenerator = jsonFactory.createGenerator(new FileOutputStream("query-output.json"));
jsonGenerator.writeStartArray();
g.V().valueMap(true).sideEffect(m -> {
    // write out one result at a time to the stream
    try {
        jsonGenerator.writeObject(m.get());
    } catch (IOException ioe) {
        ioe.printStackTrace();
    }
}).iterate();
jsonGenerator.writeEndArray();
jsonGenerator.close();

// stream it back in from the local file, but again could be S3 InputStream
final JsonParser jsonParser = jsonFactory.createParser(new FileInputStream("query-output.json"));
// first token is query result list start so skip that one
jsonParser.nextToken();
while (jsonParser.nextToken() != JsonToken.END_ARRAY) {
    // we wrote maps, so tell the streaming parser to decode maps - see console.txt
    final Object o = jsonParser.readValueAs(Map.class);
    System.out.println(String.format("Type: %s Value: %s", o.getClass().getSimpleName(), o));
}