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Tuscany SCA案例分析(二)(连载中...)

2008-01-08 12:04 218 查看
今天给大家讲的是calculator的分布式版本,在这个案例中,我们先来看看其设计图,如下:



从图中可以明显地看出有3个节点nodeA,nodeB,nodeC,而nodeA上有三个组件,nodeB和nodeC上分别有一个组件。这3个节点在同一个domain中。服务引用的关系在这里就不多说了。
那么我们下面进入开发过程了。
先建立一个普通的java project,项目名叫"MyDistributedCalculator",默认设置



在书写主要的业务逻辑单元代码之前,先象案例一一样,加入MyTuscany用户库,好,现在集中精力书写逻辑代码,因为这里对案例一有一个承接关系,所以建议看案例二之前先看明白案例一。我们这里将案例一项目中的calculator包下的除CalculatorClient.java文件外的java文件都copy到myDistributedCalculator项目的calculator包下。如下图:



这里绝大部分代码和案例一都一样,只是因为分布式的原因,所以就要修改几个接口部分的代码,因为AddServiceComponent和SubtractServiceComponent都在另外的机子上,所以在他们相应的服务接口上要声明为@Remotable,以便让nodeA上的CalculatorServiceComponent远程引用,这和案例一是不一样的地方。这里给出他们修改后的代码:




/**//*文件AddService.java*/




package calculator;




import org.osoa.sca.annotations.Remotable;






/** *//**


* The Add service interface


*/


@Remotable




public interface AddService ...{




double add(double n1, double n2);




}






/**//*文件SubtractService.java*/


package calculator;




import org.osoa.sca.annotations.Remotable;






/** *//**


* The interface for the multiply service


*/


@Remotable




public interface SubtractService ...{




double subtract(double n1, double n2);




}

接下来要做的就是要写一个domain manager类和node启动类,我们先建立node包,然后建立相应的文件,其中用于启动domain manager类的文件名为DomainNode.java,用于启动node的类文件名为CalculatorNode.java
他们分别的内容为:




/**//*CalculatorNode.java文件内容如下*/






package node;




import java.io.IOException;




import javax.xml.namespace.QName;




import org.apache.tuscany.sca.domain.SCADomain;


import org.apache.tuscany.sca.node.SCANode;


import org.apache.tuscany.sca.node.SCANodeFactory;




import calculator.CalculatorService;






/** *//**


* This client program shows how to run a distributed SCA node. In this case a


* calculator node has been constructed specifically for running the calculator


* composite. Internally it creates a representation of a node and associates a


* distributed domain with the node. This separation is made different implementations


* of the distributed domain can be provided.


*/




public class CalculatorNode ...{








public static void main(String[] args) throws Exception ...{




// Check that the correct arguments have been provided




if (null == args || args.length < 2) ...{


System.err.println("Useage: java CalculatorNode domainname nodename");


System.exit(1);


}






try ...{


String domainName = args[0];


String nodeName = args[1];




ClassLoader cl = CalculatorNode.class.getClassLoader();




SCANodeFactory nodeFactory = SCANodeFactory.newInstance();


SCANode node = nodeFactory.createSCANode(nodeName, domainName);


node.addContribution(nodeName, cl.getResource(nodeName + "/"));


//System.out.println(cl.getResource(nodeName + "/").toString());


node.deployComposite(new QName("http://sample", "Calculator"));


node.start();




// nodeA is the head node and runs some tests while all other nodes


// simply listen for incoming messages




if ( nodeName.equals("nodeA") ) ...{


// do some application stuff


CalculatorService calculatorService =


node.getDomain().getService(CalculatorService.class, "CalculatorServiceComponentA");




// Calculate


System.out.println("3 + 2=" + calculatorService.add(3, 2));


System.out.println("3 - 2=" + calculatorService.subtract(3, 2));


System.out.println("3 * 2=" + calculatorService.multiply(3, 2));


System.out.println("3 / 2=" + calculatorService.divide(3, 2));




// a little hidden loop test to put some load on the nodes




if (args.length > 2)...{




for (int i=0; i < 1000; i++)...{


// Calculate


System.out.println("3 + 2=" + calculatorService.add(3, 2));


System.out.println("3 - 2=" + calculatorService.subtract(3, 2));


System.out.println("3 * 2=" + calculatorService.multiply(3, 2));


System.out.println("3 / 2=" + calculatorService.divide(3, 2));


}


}




} else ...{


// start up and wait for messages




try ...{


System.out.println("Node started (press enter to shutdown)");


System.in.read();




} catch (IOException e) ...{


e.printStackTrace();


}


}




// stop the node and all the domains in it


node.stop();






} catch(Exception ex) ...{


System.err.println("Exception in node - " + ex.getMessage());


ex.printStackTrace(System.err);


}


}


}






/**//*DomainNode.java 文件内容如下*/




package node;




import org.apache.tuscany.sca.domain.SCADomain;


import org.apache.tuscany.sca.domain.SCADomainFactory;








/** *//**


* This server program that loads a composite to provide simple registry function.


* This server can be replaced with any registry that is appropriate but the components


* in each node that talk to the registry should be replaced also.


*/




public class DomainNode ...{




private static String DEFAULT_DOMAIN_URI = "http://localhost:8877";






public static void main(String[] args) ...{






try ...{


SCADomainFactory domainFactory = SCADomainFactory.newInstance();


SCADomain domain = domainFactory.createSCADomain(DEFAULT_DOMAIN_URI);


domain.start();




System.out.println("Domain started (press enter to shutdown)");


System.in.read();




domain.stop();




} catch (Exception e) ...{


e.printStackTrace();


}




System.out.println("Domain stopped");


}




}



这里将我自己的理解和对代码的分析写下来:
先从DomainNode.java开始分析,里面用到了两个类,SCADomainFactory 和SCADomain。代码比较简单,就是用SCADomainFactory 本身的newInstance()生成自己的实例,然后通过createSCADomain()函数生成SCADomain的实例,然后用domain.start();启动domain。这里要特别注意的是,虽然代码很简单,但其实它完成的工作可不少,首先createSCADomain()会去实例化一个实现了SCADomain接口的类,这里是SCADomainImpl类,通过查看分析tuscany的源代码,发现该类初始化函数调用了init()函数



而在init()函数中完成了一些关键的工作,其中里面有一个就是初始化一些domain manager的服务组件,那么根据什么来初始化这些组件呢,就是根据domain.composite文件,该文件的位置是在tuscany-sca-all-1.0.1-incubating.jar文件内部,如图:



该文件的内容如下:


<composite xmlns="http://www.osoa.org/xmlns/sca/1.0"


targetNamespace="http://sample"


xmlns:sample="http://sample"


xmlns:tuscany="http://tuscany.apache.org/xmlns/sca/1.0"


name="Domain">




<component name="domain">


<tuscany:implementation.resource location="webroot"/>


<service name="Resource">


<tuscany:binding.http uri="http://localhost:8877/domain"/>


</service>


</component>




<component name="DomainManagerComponent">


<implementation.java class="org.apache.tuscany.sca.domain.impl.DomainManagerServiceImpl"/>


<service name="DomainManagerInitService">


<interface.java interface="org.apache.tuscany.sca.domain.DomainManagerInitService"/>


<binding.sca/>


</service>


<service name="DomainManagerNodeEventService">


<interface.java interface="org.apache.tuscany.sca.domain.DomainManagerNodeEventService"/>


<binding.ws uri="http://localhost:8877/DomainManagerComponent/DomainManagerNodeEventService"/>


</service>


<service name="DomainManagementService">


<interface.java interface="org.apache.tuscany.sca.domain.management.DomainManagementService"/>


<tuscany:binding.jsonrpc uri="http://localhost:8877/DomainManagerComponent/DomainManagementService"/>


</service>


</component>




</composite>

注意到上面的<tuscany:binding.http uri="http://localhost:8877/domain"/>,这里是这些组件注册为相应的servlet时的uri地址,这也就要求DomainNode.java中的private static String DEFAULT_DOMAIN_URI = "http://localhost:8877";必须是domain manager的根地址,必须和tuscany:binding的uri保持一致。到目前为止,我们就解释完DomainNode的内容了,下面我们看看复杂些的CalculatorNode.java的内容。其实他的内容仔细看也不复杂,主干部分的代码功能主要是从命令行中接受两个参数,一个是domainname,一个是nodename,然后根据这些信息来启动node,这里跟前面的DomainNode有点类似,也是先用SCANodeFactory的newInstance()实例化自身,再用createSCANode实例化出一个实现了SCANode接口的类,这里是SCANodeImpl类,该类的初始化函数中也执行了其相应的init()函数,而init()函数则完成了对node管理组件的初始化,是根据tuscany-sca-all-1.0.1-incubating.jar文件内部的node.composite文件,下面将其文件内容列出如下:


<composite xmlns="http://www.osoa.org/xmlns/sca/1.0"


targetNamespace="http://management"


xmlns:sample="http://management"


xmlns:tuscany="http://tuscany.apache.org/xmlns/sca/1.0"


name="Management">




<component name="DomainManagerComponent">


<implementation.java class="org.apache.tuscany.sca.node.impl.DomainManagerServiceImpl"/>


<reference name="domainManager">


<interface.java interface="org.apache.tuscany.sca.domain.DomainManagerNodeEventService"/>


<binding.ws uri="http://localhost:8878/DomainManagerComponent/DomainManagerNodeEventService"/>


</reference>


</component>




<component name="NodeManagerComponent">


<implementation.java class="org.apache.tuscany.sca.node.impl.NodeManagerServiceImpl"/>


<service name="NodeManagerInitService">


<interface.java interface="org.apache.tuscany.sca.node.NodeManagerInitService"/>


<binding.sca/>


</service>


<service name="NodeManagerService">


<interface.java interface="org.apache.tuscany.sca.node.NodeManagerService"/>


<binding.ws uri="http://localhost:8878/NodeManagerComponent/NodeManagerService"/>


</service>


<service name="ComponentManagerService">


<interface.java interface="org.apache.tuscany.sca.node.ComponentManagerService"/>


<tuscany:binding.jsonrpc uri="http://localhost:8878/NodeManagerComponent/ComponentManagerJson"/>


</service>


</component>




<component name="node">


<tuscany:implementation.resource location="webroot"/>


<service name="Resource">


<tuscany:binding.http uri="http://localhost:8878/node"/>


</service>


</component>




</composite>



通过这些信息再与下图相比来理解吧



好了,这里有点初学者会有点糊涂,看看DomainNode.java就可以知道,先要启动nodeB和nodeC,因为他们是被引用的服务组件,再是启动nodeA,因为它上的CalculatorServiceComponent才能引用到相应的服务。这里有点急了,都忘记要写装配文件.composite文件了,否则怎么装配这些服务呀,执行结果要等到写完正确的装配文件再说,开动吧。先按下图建立目录和文件,写nodeA的composite文件和sca-contribution.xml文件,列出内容如下:



我在分布式SCADomain说明中说了如何加载contribution的,sca-contribution.xml里面就说明了哪些composite可部署,Calculator.composite则告诉了该构件中有哪里组件。
下面给出nodeA下的sca-contribution.xml和Calculator.composite内容:


<!--sca-contribution.xml内容 -->


<?xml version="1.0" encoding="UTF-8"?>




<contribution xmlns="http://www.osoa.org/xmlns/sca/1.0"


targetNamespace="http://sample"


xmlns:sample="http://sample">


<deployable composite="sample:Calculator"/>


</contribution>


<!--


Calculator.composite文件内容


-->


<?xml version="1.0" encoding="UTF-8"?>




<composite xmlns="http://www.osoa.org/xmlns/sca/1.0"


targetNamespace="http://sample"


xmlns:sample="http://sample"


name="Calculator">




<component name="CalculatorServiceComponentA">


<implementation.java class="calculator.CalculatorServiceImpl"/>


<reference name="addService" target="AddServiceComponentB" />


<reference name="subtractService" target="SubtractServiceComponentC" />


<reference name="multiplyService" target="MultiplyServiceComponentA"/>


<reference name="divideService" target="DivideServiceComponentA" />


</component>




<component name="MultiplyServiceComponentA">


<implementation.java class="calculator.MultiplyServiceImpl" />


</component>




<component name="DivideServiceComponentA">


<implementation.java class="calculator.DivideServiceImpl" />


</component>




</composite>

每个相应的node目录下的sca-contribution.xml内容都一样的,不同的只是Calculator.composite里的内容,因为在nodeA中只有两个组件MultiplyServiceComponentA、DivideServiceComponentA还有些引用。其他node的Calculator.composite内容如下:


<?xml version="1.0" encoding="UTF-8"?>


<!--


nodeB下的Calculator.composite内容


-->


<composite xmlns="http://www.osoa.org/xmlns/sca/1.0"


targetNamespace="http://sample"


xmlns:sample="http://sample"


name="Calculator">




<component name="AddServiceComponentB">


<implementation.java class="calculator.AddServiceImpl" />


</component>




</composite>


<?xml version="1.0" encoding="UTF-8"?>


<!--


nodeC下的Calculator.composite内容


-->


<composite xmlns="http://www.osoa.org/xmlns/sca/1.0"


targetNamespace="http://sample"


xmlns:sample="http://sample"


name="Calculator">




<component name="SubtractServiceComponentC">


<implementation.java class="calculator.SubtractServiceImpl" />


<service name="SubtractService">


<binding.sca uri="http://localhost:8086/SubtractServiceComponentC"/>


</service>


</component>




</composite>

好了,装配的配置文件都搞好了,下面我们来运行下,看看结果如何。
先从eclipse里象启动一般java程序一样启动DomainNode.java



然后再要启动CalculatorNode.java,这里启动要传入不同的参数,这里给出启动nodeB时打开启动对话框配置的传入参数图:



启动nodeC和nodeA的参数只要用nodeC和nodeA替换nodeB就可以了,给出个最终结果图吧,如下:



记住启动的顺序,先要启动nodeB和nodeC,最后启动nodeA呀,成功了记得告诉我,谢谢



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