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With old component container managed by ComponentLocator class, we don't distinguish framework components and regular components that implement varios CloudStack business logic, we started to separate framework components and business logic components in Spring, as the result, there are separated context configuration file, these two files are applicationContext.xml.in and componentContext.xml.in, following is some sample content from Javelin

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<beans xmlns="http://www.springframework.org/schema/beans"

  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 

  xmlns:context="http://www.springframework.org/schema/context"

  xmlns:tx="http://www.springframework.org/schema/tx" 

  xmlns:aop="http://www.springframework.org/schema/aop"

  xsi:schemaLocation="http://www.springframework.org/schema/beans

                      http://www.springframework.org/schema/beans/spring-beans-3.0.xsd

                      http://www.springframework.org/schema/tx&nbsp;

                      http://www.springframework.org/schema/tx/spring-tx-3.0.xsd

                      http://www.springframework.org/schema/aop

                      http://www.springframework.org/schema/aop/spring-aop-3.0.xsd

                      http://www.springframework.org/schema/context

                      http://www.springframework.org/schema/context/spring-context-3.0.xsd">                     

  <!--

      Compose a CloudStack deployment with selected components here

  -->

  <bean id="databaseUpgradeChecker" />

  <bean id="management-server" class ="com.cloud.server.ManagementServerExtImpl" />

  <bean id="configuration-server" />

  <bean id="clusterManagerImpl" />

  <bean id="clusteredAgentManagerImpl" />

  <bean id="clusteredVirtualMachineManagerImpl" />

  <bean id="highAvailabilityManagerExtImpl" />

  <!-- bean id="bareMetalVmManagerImpl" / -->

  <bean id="userVmManagerImpl" />

  <bean id="consoleProxyManagerImpl" />

  <bean id="securityGroupManagerImpl2" />

  <bean id="premiumSecondaryStorageManagerImpl" />

  <bean id="randomlyIncreasingVMInstanceDaoImpl" /> 

  <!--

      Network Elements

  -->

  <bean id="Ovs">

    <property name="name" value="Ovs"/>

  </bean>

  <bean id="ExternalDhcpServer">

    <property name="name" value="ExternalDhcpServer"/>

  </bean>

  <bean id="BareMetal">

    <property name="name" value="BareMetal"/>

  </bean>

  <bean id="SecurityGroupProvider">

    <property name="name" value="SecurityGroupProvider"/>

  </bean>

  <bean id="VirtualRouter">

    <property name="name" value="VirtualRouter"/>

  </bean>

  <bean id="VpcVirtualRouter">

    <property name="name" value="VpcVirtualRouter"/>

  </bean>

  <bean id="NiciraNvp">

    <property name="name" value="NiciraNvp"/>

  </bean>

  

  

</beans> 

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Following is an example of such hacking way, inside BaseCmd class, developer tried to resolve all the references for every used components into static variables at  BaseCmd. It also means that, when you add a new Command class to the system, you will have to remember to do something about your new service at BaseCmd class

public

abstract

class BaseCmd&nbsp;{ &nbsp; &nbsp; static public&nbsp;NetworkACLService \_networkACLService; }

class BaseCmd{   static public NetworkACLService _networkACLService; 
 }

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With Spring, developer can now always use @Inject annotation to declare such reference. One of the top two reasons for us to try Spring experiments in Javelin, since with more complete dependency injection, it gives us a cleaner component coding practice. (the other top reason is that we have broader integration supports from many other third-party vendors, i.e., JUnit)

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@Component

public class ConfigurationDaoImpl extends GenericDaoBase<ConfigurationVO, String> implements ConfigurationDao {

&nbsp; &nbsp;@PostConstruct

&nbsp; &nbsp; void initComponent() &nbsp;{

&nbsp; &nbsp; }

}

4.4 Be aware of Spring proxy mode

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