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最近开始研究janusgraph图数据库，想通过开源图数据库开发一套变成语言知识平台。之前有研究过janusgraph图计算相关的代码，结果比较失望，目前janusgraph只支持tinkerpop内置的几个图计算算法包括pagerank、最短路径、连通图。参考Tinkerpop图计算。在计算性能上还有待优化。

janusgraph整体来说还是比较难上手的，这也和tinkerpop本身复杂的服务端配置文件相关，并且启动方式较为特殊，实际上是通过grenmlin启动脚本实现，jasusgraph通配置文件已插件的方式嵌入到了GremlinServer中，官网说本质上是一些jar包组成不带main方法的。所以实际上系统中显示的进程是org.apache.tinkerpop.gremlin.server.GremlinServer

说了很多废话，接下来开始学习janusgraph的动态图管理。

在janusgraph中通过修改server.yaml文件中的graphs选项可以创建一张或者多张图

这里我定义了graph0和graph1两张图，使用了不同的图配置文件，这些配置信息将决定图的后端存储类型和索引类型，建议文件名为janusgraph-{storage}-{index}.properties.

问题是如何访问这两个图？

需要在groovy脚本变量中配置图的遍历器(GraphTraversalSoource),修改scripts/empty-sample.groovy文件

// Copyright 2019 JanusGraph Authors

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

// an init script that returns a Map allows explicit setting of global bindings.

def globals = [:]

// defines a sample LifeCycleHook that prints some output to the Gremlin Server console.

// note that the name of the key in the "global" map is unimportant.

globals << [hook : [

onStartUp: { ctx ->

ctx.logger.info("Executed once at startup of Gremlin Server.")

},

onShutDown: { ctx ->

ctx.logger.info("Executed once at shutdown of Gremlin Server.")

}

] as LifeCycleHook]

// define the default TraversalSource to bind queries to - this one will be named "g".

globals << [g : graph0.traversal(),g1 : graph1.traversal()]

globals实际是全局可访问的键值对变量，因为gremlin内部使用groovy脚本引擎执行语句，所以事先声明好g和g1两个变量保证控制台程序能够访问得到。

动态图管理

上述方法在数据库启动前确定图的名称和配置，在数据库运行的过程中无法进行图的扩展。比如有需求添加新的图。ConfiguredGraphFactory能够弥补静态图配置的不足，官网描述如下：

The JanusGraph Server can be configured to use the`ConfiguredGraphFactory`. The`ConfiguredGraphFactory`is an access point to your graphs, similar to the`JanusGraphFactory`. These graph factories provide methods for dynamically managing the graphs hosted on the server.

ConfiguredGraphFactory提供方法动态管理服务器上的图列表。从源码上看静态方法提供了创建、打开、关闭、删除操作，配置模板创建更新、删除等操作。

开启配置步骤：

配置管理

修改图属性配置文件conf/janusgraph-configurationmanagement.properties

gremlin.graph=org.janusgraph.core.ConfiguredGraphFactory

graph.graphname=ConfigurationManagementGraph

#后端使用berkeleyDB

storage.backend=berkeleyje

storage.directory=./db/berkeley

#使用lucene作为索引

index.search.backend=lucene

index.search.directory=./db/searchindex

修改server启动配置文件conf/gremlin-server/gremlin-server-configurationmanagement.yaml,配置graphManager和graphs.graphManger的作用是维护graphname->Graph和graphname->TraversalSource的映射关系

host: 0.0.0.0

port: 8182

scriptEvaluationTimeout: 30000

channelizer: org.apache.tinkerpop.gremlin.server.channel.WebSocketChannelizer

graphManager: org.janusgraph.graphdb.management.JanusGraphManager

graphs: {

ConfigurationManagementGraph: conf/janusgraph-configurationmanagement.properties

}

scriptEngines: {

gremlin-groovy: {

plugins: { org.janusgraph.graphdb.tinkerpop.plugin.JanusGraphGremlinPlugin: {},

org.apache.tinkerpop.gremlin.server.jsr223.GremlinServerGremlinPlugin: {},

org.apache.tinkerpop.gremlin.tinkergraph.jsr223.TinkerGraphGremlinPlugin: {},

org.apache.tinkerpop.gremlin.jsr223.ImportGremlinPlugin: {classImports: [java.lang.Math], methodImports: [java.lang.Math#*]},

org.apache.tinkerpop.gremlin.jsr223.ScriptFileGremlinPlugin: {files: [scripts/empty-configurationmanagement.groovy]}}}}

serializers:

- { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}

- { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0, config: { serializeResultToString: true }}

- { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV3d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}

# Older serialization versions for backwards compatibility:

- { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}

- { className: org.apache.tinkerpop.gremlin.driver.ser.GryoLiteMessageSerializerV1d0, config: {ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}

- { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0, config: { serializeResultToString: true }}

- { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerGremlinV2d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}

- { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerGremlinV1d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistryV1d0] }}

- { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV1d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistryV1d0] }}

processors:

- { className: org.apache.tinkerpop.gremlin.server.op.session.SessionOpProcessor, config: { sessionTimeout: 28800000 }}

- { className: org.apache.tinkerpop.gremlin.server.op.traversal.TraversalOpProcessor, config: { cacheExpirationTime: 600000, cacheMaxSize: 1000 }}

metrics: {

consoleReporter: {enabled: true, interval: 180000},

csvReporter: {enabled: true, interval: 180000, fileName: /tmp/gremlin-server-metrics.csv},

jmxReporter: {enabled: true},

slf4jReporter: {enabled: true, interval: 180000},

gangliaReporter: {enabled: false, interval: 180000, addressingMode: MULTICAST},

graphiteReporter: {enabled: false, interval: 180000}}

maxInitialLineLength: 4096

maxHeaderSize: 8192

maxChunkSize: 8192

maxContentLength: 65536

maxAccumulationBufferComponents: 1024

resultIterationBatchSize: 64

writeBufferLowWaterMark: 32768

writeBufferHighWaterMark: 65536

修改scripts/empty-sample.groovy文件,注释掉全局变量g.

//globals << [g : graph0.traversal(),g1 : graph1.traversal()]

启动janusgraph核心进程(GremlinServer)

#WINDOWS10

.\bin\gremlin-server.bat .\conf\gremlin-server\gremlin-server-configurationmanagement.yaml

启动janusgraph客户端(GremlinConsole)

# WINDOWS10

.\gremlin.bat

gremlin>:remote connect tinkerpop.server conf/remote.yaml session

gremlin>:remote console

尝试获取ConfiguredGraphFactory图管理器，

gremlin> ConfiguredGraphFactory

==>class org.janusgraph.core.ConfiguredGraphFactory

注：如果出现相关的错误，请检查properties文件中的gremlin.graph和graph.graphname是否正确

No such property: ConfiguredGraphFactory for class: Script7

Type ':help' or ':h' for help.

Display stack trace? [yN]

ConfiguredGraphFactory管理API使用

ConfiguredGraphFactory

创建图配置

map=new HashMap();

map.put('storage.backend','berkeleyje');

map.put('storage.directory','../db/berkeley');

map.put('index.search.backend','lucene');

map.put('index.search.directory','../db/lucene');

map.put('graph.graphname','graph0');

config = new MapConfiguration(map);

#创建图graph0

ConfiguredGraphFactory.createConfiguration(config);

#创建图graph1

map.put('graph.graphname','graph1');

config = new MapConfiguration(map);

ConfiguredGraphFactory.createConfiguration(config);

#获取所有图名

ConfiguredGraphFactory.getGraphNames();

==>graph1

==>graph0

实用现代javascript模块化系列

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