OSGi/蓝图中的服务参考不能正常工作

Question

我目前有两个 OSGi 包（bundle1 和 bundle2）都通过 EBA 中的蓝图公开服务。在bundle2 的blueprint.xml 中，我想从bundle1 引用一个服务并将其注入 到BuildService（下面的代码）中，因为BuildService 将用于调用TicketService。然而，这会导致超时异常（也在下面）。似乎 BuildService 永远不会在 OSGi 中注册。我该如何做这样的事情？

blueprint.xml 为bundle1：

<?xml version="1.0" encoding="UTF-8"?>
<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0" xmlns:bptx="http://aries.apache.org/xmlns/transactions/v1.0.0">

    <bean id="TicketServiceBean" class="com.example.b2.impl.TicketServiceImpl">
        <bptx:transaction value="Required" method="*" />
    </bean>

        <service ranking="0" id="TicketService" interface="com.example.b2.service.TicketService" ref="TicketServiceBean">
        <service-properties>
            <entry key="service.exported.interfaces" value="*" />
        </service-properties>
    </service>  

</blueprint>

blueprint.xml 为bundle2

<?xml version="1.0" encoding="UTF-8"?>
<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0">

    <bean 
        id="BuildServiceImplBean"
        class="com.example.b1.impl.BuildServiceImpl" 
        activation="eager" >
        <property name="ticketService" ref="TicketServiceRef" />
    </bean>  


    <service    
        id="BuildService" 
        ref="BuildServiceImplBean"
        interface="com.example.b1.service.BuildService"
        activation="eager"> 

        <service-properties>
            <entry key="service.exported.interfaces" value="*" />
        </service-properties>

    </service>



    <reference 
        id="TicketServiceRef" 
        interface="com.example.b2.service.TicketService" 
        availability="mandatory"
        activation="eager" />


</blueprint>

BuildService 的实现：

public class BuildServiceImpl implements BuildService {

    private TicketService ticketService;

    @Override
    public TicketBuildResponse ticketBuild(TicketBuildRequest ticketBuildRequest) throws BuildServiceException {

        //do stuff here
    }



    public TicketService getTicketService() {
        return ticketService;
    }

    public void setTicketService(TicketService ticketService) {
        this.ticketService = ticketService;
    }


}

启动应用程序服务器（Websphere）时出现以下异常：

  BlueprintCont E org.apache.aries.blueprint.container.BlueprintContainerImpl$1 run Unable to start blueprint container for bundle com.example.b1.module due to unresolved dependencies [(objectClass=com.example.b2.service.TicketService)]
                                     java.util.concurrent.TimeoutException
        at org.apache.aries.blueprint.container.BlueprintContainerImpl$1.run(BlueprintContainerImpl.java:273)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:453)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:315)
        at java.util.concurrent.FutureTask.run(FutureTask.java:150)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:98)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:207)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at java.lang.Thread.run(Thread.java:736)

Answer 1

这里是解决方案：OSGi 应用程序运行时处理远程服务与本地服务不同，因为不同的默认调用语义（本地传递引用与远程传递值）。为了防止应用程序意外调用仅为按值传递调用设计的导出服务，它对本地查找隐藏。

解决方案是导出同一个 bean 两次，一次用于远程调用，第二次用于本地调用。换句话说，您将添加另一个具有相同配置但没有service.exported.interfaces 属性的<service /> 元素。

<service ranking="0" id="TicketServiceExport" interface="com.example.b2.service.TicketService" ref="TicketServiceBean">
    <service-properties>
        <entry key="service.exported.interfaces" value="*" />
    </service-properties>
</service>  

<service ranking="0" id="TicketService" interface="com.example.b2.service.TicketService" ref="TicketServiceBean"/>

websphere 中其实也有一个 osgi 控制台，可以在[local websphere installation]/profiles/[profileName]/bin/osgiApplicationConsole.bat 下找到。启动后，help() 会为您提供命令列表。要查看从 SCA 导入的服务，您首先连接到您的应用程序（例如 connect(2)，其中应用程序的编号在 list() 命令的结果中给出）。然后，您可以通过 services("(service.imported=true)") 查看 SCA 添加的服务代理。命令services() 将列出应用程序中的所有服务。