有了分布式網(wǎng)格，一個(gè)很樸素的想法就是能將自己的應(yīng)用部署到網(wǎng)格中運(yùn)行，并且網(wǎng)格可以保證HA和failover。 Ignite可以非常便利的實(shí)現(xiàn)這一點(diǎn)，廢話不多說(shuō)，直接開(kāi)干。

需求

一個(gè)定時(shí)任務(wù)，可以根據(jù)指定的時(shí)間周期向client節(jié)點(diǎn)發(fā)出信息

實(shí)現(xiàn)

• 作業(yè)調(diào)度

需求中需要服務(wù)可以周期性執(zhí)行，顯然需要有簡(jiǎn)單的作業(yè)調(diào)度功能。Ignite中有scheule模塊，只不過(guò)由于是LGPL的license，因此build-in的模塊中沒(méi)有，需要手動(dòng)build

1. 下載Ignite源碼包，如 apache-ignite-2.2.0-src.zip

2. 解壓并進(jìn)入apache-ignite-2.2.0-src\modules\schedule目錄

3. 執(zhí)行命令 mvn clean package -DskipTests -Prelease,lgpl

4. 進(jìn)入target目錄，將ignite-schedule-2.2.0.jar和libs\cron4j-2.2.5.jarcopy至IGNITE_HOME\libs目錄下

這樣，Ignite就可以調(diào)度作業(yè)了

• 實(shí)現(xiàn)service

Ignite的Servcie Grid服務(wù)需要實(shí)現(xiàn)IgniteServices接口， 而Ignite可以保證服務(wù)可以以Node Singleton或者Cluster Singleton模式運(yùn)行并實(shí)現(xiàn)負(fù)載均衡

public class MyServiceImpl implements Service {

    @IgniteInstanceResource
    private Ignite ignite;
    private String svcName;

    @Override
    public void init(ServiceContext ctx) {
        svcName = ctx.name();
        System.out.println("Service was initialized: " + svcName);
        IgniteMessaging rmtMsg = ignite.message(ignite.cluster().forClients());
        rmtMsg.remoteListen("MyOrderedTopic", (nodeId, msg) -> {
        System.out.println("Received ordered message [msg=" + msg + ", from=" + nodeId + ']');
        return true; // Return true to continue listening.
         });

        ignite.scheduler().scheduleLocal(
                new Runnable() {
                    @Override
                    public void run() {
                        rmtMsg.send("MyOrderedTopic", "hello");
                        System.out.println("Send message");
                    }
                }, "* * * * *" //send msg every mintue
        );
    }

    @Override
    public void cancel(ServiceContext ctx) {
        System.out.println("Service was cancelled: " + svcName);
    }

    @Override
    public void execute(ServiceContext ctx) {
        // Since our service is simply demo, there is nothing we need
        // to do in order to start it up.
        System.out.println("Executing distributed service: " + svcName);
    }
}

• build service jar 包

通過(guò)maven將此代碼build成jar包后放置到IGNITE_HOME\libs目錄下， 由于Ignite現(xiàn)不支持service的Zero Deployment， 因此此jar包需要放置到所有需要運(yùn)行此服務(wù)的所有節(jié)點(diǎn)中

• 配置service服務(wù)

打開(kāi)配置文件，編輯如下內(nèi)容

<bean id="grid.cfg" class="org.apache.ignite.configuration.IgniteConfiguration">
        <property name="serviceConfiguration">
            <list>
                <bean class="org.apache.ignite.services.ServiceConfiguration">
                    <property name="name" value="MyClusterSingletonSvc"/>
                    <property name="maxPerNodeCount" value="1"/>
                    <property name="totalCount" value="1"/>
                    <property name="service">
                    <ref bean="myServiceImpl"/>
                    </property>
                </bean>
            </list>
        </property>
    </bean>
    <bean id="myServiceImpl" class="com.abc.igniteservicedemo.MyServiceImpl"/>
</bean>

這里我們?cè)O(shè)定此服務(wù)為Cluster Singleton模式，如需要設(shè)置Node Singleton模式，去掉

<property name="totalCount" value="1"/>

即可

• 啟動(dòng)Ignite后會(huì)看到如下輸出

[18:10:55] Security status [authentication=off, tls/ssl=off]
Service was initialized: MyClusterSingletonSvc
Executing distributed service: MyClusterSingletonSvc
[18:10:59] Performance suggestions for grid (fix if possible)
... ...
[18:10:59] Topology snapshot [ver=1, servers=1, clients=0, CPUs=4, heap=1.0GB]
Send message
Send message

至此，我們實(shí)現(xiàn)了一個(gè)簡(jiǎn)單的service grid服務(wù)