GraphSON Reader and Writer Library
<dependency>
<groupId>com.tinkerpop.blueprints</groupId>
<artifactId>blueprints-core</artifactId>
<version>??</version>
</dependency>The JSON reader and writer package allows an entire graph to be streamed to and from the standard JSON format utilized across the TinkerPop stack called GraphSON. The format comes in two flavors: one that uses explicit data typing within the JSON and one that does not. For most scenarios, standard JSON without data typing should generally be acceptable. Using the more verbose outputting of explicit data types only provides the added value of ensuring that numeric values are converted properly (ie. float versus double).
The following example shows the format without explicit data types:
{
"graph": {
"vertices": [
{
"name": "lop",
"lang": "java",
"_id": "3",
"_type": "vertex"
},
{
"name": "vadas",
"age": 27,
"_id": "2",
"_type": "vertex"
},
{
"name": "marko",
"age": 29,
"_id": "1",
"_type": "vertex"
},
{
"name": "peter",
"age": 35,
"_id": "6",
"_type": "vertex"
},
{
"name": "ripple",
"lang": "java",
"_id": "5",
"_type": "vertex"
},
{
"name": "josh",
"age": 32,
"_id": "4",
"_type": "vertex"
}
],
"edges": [
{
"weight": 1,
"_id": "10",
"_type": "edge",
"_outV": "4",
"_inV": "5",
"_label": "created"
},
{
"weight": 0.5,
"_id": "7",
"_type": "edge",
"_outV": "1",
"_inV": "2",
"_label": "knows"
},
{
"weight": 0.4000000059604645,
"_id": "9",
"_type": "edge",
"_outV": "1",
"_inV": "3",
"_label": "created"
},
{
"weight": 1,
"_id": "8",
"_type": "edge",
"_outV": "1",
"_inV": "4",
"_label": "knows"
},
{
"weight": 0.4000000059604645,
"_id": "11",
"_type": "edge",
"_outV": "4",
"_inV": "3",
"_label": "created"
},
{
"weight": 0.20000000298023224,
"_id": "12",
"_type": "edge",
"_outV": "6",
"_inV": "3",
"_label": "created"
}
]
}
}The following example shows the format with explicit data types:
{
"embeddedTypes":true,
"vertices": [
{
"name": {
"type": "string",
"value": "lop"
},
"lang": {
"type": "string",
"value": "java"
},
"_id": "3",
"_type": "vertex"
},
{
"name": {
"type": "string",
"value": "vadas"
},
"age": {
"type": "integer",
"value": 27
},
"_id": "2",
"_type": "vertex"
},
{
"name": {
"type": "string",
"value": "marko"
},
"age": {
"type": "integer",
"value": 29
},
"_id": "1",
"_type": "vertex"
},
{
"name": {
"type": "string",
"value": "peter"
},
"age": {
"type": "integer",
"value": 35
},
"_id": "6",
"_type": "vertex"
},
{
"name": {
"type": "string",
"value": "ripple"
},
"lang": {
"type": "string",
"value": "java"
},
"_id": "5",
"_type": "vertex"
},
{
"name": {
"type": "string",
"value": "josh"
},
"age": {
"type": "integer",
"value": 32
},
"_id": "4",
"_type": "vertex"
}
],
"edges": [
{
"weight": {
"type": "float",
"value": 1
},
"_id": "10",
"_type": "edge",
"_outV": "4",
"_inV": "5",
"_label": "created"
},
{
"weight": {
"type": "float",
"value": 0.5
},
"_id": "7",
"_type": "edge",
"_outV": "1",
"_inV": "2",
"_label": "knows"
},
{
"weight": {
"type": "float",
"value": 0.4000000059604645
},
"_id": "9",
"_type": "edge",
"_outV": "1",
"_inV": "3",
"_label": "created"
},
{
"weight": {
"type": "float",
"value": 1
},
"_id": "8",
"_type": "edge",
"_outV": "1",
"_inV": "4",
"_label": "knows"
},
{
"weight": {
"type": "float",
"value": 0.4000000059604645
},
"_id": "11",
"_type": "edge",
"_outV": "4",
"_inV": "3",
"_label": "created"
},
{
"weight": {
"type": "float",
"value": 0.20000000298023224
},
"_id": "12",
"_type": "edge",
"_outV": "6",
"_inV": "3",
"_label": "created"
}
]
}There are a few differences between the formats. If types are embedded, the JSON must start with an embeddedTypes key with a value of true. This key acts as a hint to the reader that it must extract property values in a different manner. If the key is omitted, that setting is assumed to be false.
All values of keys, short of the values for reserved keys that start with an underscore, must contain an object that has two keys: type and value. The type must be one of the following: boolean, string, integer, long, float, double, list, or map.
If the type is a map or a list, then each component object that make up that key must use that same format. For example:
"someMap": {
"name": {"type":"string", "value":"william"},
"age": {"type":"int", "value":76}
},
"someList" [{"type":"int", "value":1},{"type":"int", "value":2},{"type":"int", "value":3}]Please note that complex objects stored as properties will be converted to strings by way of the object’s toString method.
To output a graph in JSON format, pass the graph into the GraphJSONWriter constructor, then call outputGraph:
Graph graph = ...
OutputStream out = ...
GraphSONWriter writer = new GraphSONWriter(graph);
writer.outputGraph(out);The GraphSONReader works in a similar format. Simply pass what would likely be an empty graph into the constructor, then call inputGraph:
Graph graph = ...
InputStream in = ...
GraphSONReader reader = new GraphSONReader(graph);
reader.inputGraph(in);There are a number of static method overloads that offer more options and control.