SCA概念与应用实践(7.SCA装配模型--7.8连线 wire)

 

7.8.        连线（wire）

Wire是用来连接同一composite中的reference和service。

定义wire有两种方法：一是使用reference的属性target，第二种是使用wire连线

7.8.1.       使用reference的属性target

Ø         删除原来的wire那根线

 

图7_8_1

Ø         在RestaurantServiceComponent的reference billService上设置target属性，可以从target2中选择可用的service

 

图7_8_2

保存后，会显示一根黄色的wire连线

 

图7_8_3

Ø         运行TipServiceServer和RestaurantServiceServer, 用soapUI测试，运行后得到bill结果

Ø         打开Restaurant2.composite，可以看到reference billservice上的target的定义, target的格式是<component-name>/<service-name>

  <sca:component name="RestaurantServiceComponent">

    <sca:implementation.java class="restaurant2.lib.RestaurantServiceImpl"/>

    <sca:reference name="menuService" autowire="false"/>

    <sca:reference name="billService" target="BillServiceComponent/BillService"/>

    <sca:service name="RestaurantService">

      <sca:interface.wsdl interface="http://api.restaurant2/#wsdl.interface(RestaurantService)"/>

      <sca:binding.ws uri="http://localhost:8085/RestaurantService"/>

    </sca:service>

  </sca:component>

7.8.2.       通过wire连线定义

黑色的实线就是wire连线。

 

图7_8_4

打开Restaurant2.composite，可以看到reference menuservice上的wire的定义

<sca:composite xmlns:frascati="http://frascati.ow2.org" xmlns:instance="http://www.w3.org/2004/08/wsdl-instance" xmlns:sawsdl="http://www.w3.org/ns/sawsdl" xmlns:sca="http://www.osoa.org/xmlns/sca/1.0" xmlns:tuscany="http://tuscany.apache.org/xmlns/sca/1.0" name="Restaurant2" targetNamespace="http://eclipse.org/Restaurant2/src/Restaurant2">

 …………

  <sca:wire source="RestaurantServiceComponent/menuService" target="MenuServiceComponent/MenuService"/>

</sca:composite>

 

选中wire连线，在properties中可以查看该wire的属性

 

图7_8_5

Source和target都是必须的，格式分别为<component-name>/<reference-name>，<component-name>/<service-name>

7.8.3.   wire的条件

必须满足以下条件才能wire source（reference）到target（service）：

Ø         source的interface与target的interface必须同时为远程接口或同时为本地接口

Ø         target interface上的operation必须与source的interface的operation相同，或者要么前者是后者的超集。

Ø         对于一个operation，名字、输入参数类型和输出参数类型必须都相同。

Ø         输入参数类型与输出参数类型的顺序也必须相同。

Ø         source期望的Fault和Exception集必须与target上说明的相同，或者前者是后者的超集。

Ø         两个接口的其他的属性必须相互匹配，包括scope和callback interface。

7.8.4.       编程注意

Service的客户端（reference就是service的客户端，当然其他调用service的程序也称为service的客户端）不能在运行时试图获取service实现的其他接口。比如service的实现，就是component的implementation，中定义了10个operations，而在service的interface中只声明了4个，那个service的客户端只能用这4个operations，不能试图获取其他六个方法。在java中我们可以用instanceof判断是不是某个类，然后强制转换类型，就可以调用该类里面的方法。在这里是不可以这么做的。 SCA的实现（tuscany就是一个SCA实现）可能给所有的wires都使用proxy，所以传到客户端里的对象（service object）只是业务接口，并不是真正的实现，即使interface是local的，客户端和service运行在同一进程中，也是不可以的。

 

7.8.5.       autowire 自动连线

7.8.5.1.       说明

autowire用来简化composite的装配。自动连线可以让component reference自动连线到满足的component service上，而不需要显示的创建连线。启用自动连线后，没有被promote的service 和没有被显示连线的component reference会自动连线到同一composite中的某个符合条件，interface相匹配的service。默认不使用自动连线。通过autowire属性来设置使用与否。composite，component 和Reference上都可以设置autowire属性。从上到下是继承关系。如果下层没有显式说明autowire属性，则使用上层元素的设置。如果该层有设置，那么就使用自己设置的值。比如reference上显示设置autowire属性为false，那么该reference上就不使用autowire功能，不管上层component和composite上怎么设置。

 

图7_8_6

7.8.5.2. 查找target原则和处理目标service的方式

如果reference使用自动连线，则在composite中查找与该reference相兼容的service。条件是：

Ø         Service的interface必须与reference的interface兼容，看14.8.3。

Ø         Service上intents，policy sets和bindings必须与reference上的相兼容

如果对于一个reference，查找到了多于1个的service，那么要看reference的multiplicity设置：

Ø         对于multiplicity为0..1和1..1的，SCA运行时会选择其中一个service连线

Ø         对于multiplicity为0..n和1..n的，将引用连线到所有的service。

如果对于一个reference，没有查找到可用service，那么也要看multiplicity设置：

Ø         对于multiplicity为0..1和0..n的，没有问题。

Ø         对于multiplicity为1..1和1..n的，因为reference必须要连到service，运行时会报错

 

7.8.5.3.       例子

Ø         设置在RestaurantServiceComponent的reference menuService上属性autowire为true

 

图7_8_7

保存后会发现原来的wire变红，这个wire需要被删掉

 

图7_8_8

Ø         删掉原来的wire

 

图7_8_9

Ø         运行TipServiceServer和RestaurantServiceServer, 用soapUI测试，调用getMenu，会得到

 

图7_8_10

Ø         如果现在把autowire改为false，再运行测试，会得到NPE

Jul 8, 2010 2:22:59 PM org.apache.tuscany.sca.binding.ws.axis2.Axis2ServiceInOutSyncMessageReceiver invokeBusinessLogic

SEVERE: java.lang.NullPointerException

org.osoa.sca.ServiceRuntimeException: java.lang.NullPointerException

   

……  ……

Caused by: java.lang.NullPointerException

    at restaurant2.lib.RestaurantServiceImpl.getMenus(RestaurantServiceImpl.java:33)

7.8.5.4.       例子演示autowire的多种情况

Ø         创建一个新的project

 

图7_8_11

Ø         创建一个新composite

 

 

图7_8_12

AutoWiredReferences.composite 内容为：

 <?xml version="1.0" encoding="UTF-8"?> <composite xmlns="http://www.osoa.org/xmlns/sca/1.0" xmlns:foo="http://foo" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" autowire="true" name="AutowireReferences" targetNamespace="http://foo"> <component autowire="false" name="AComponent"> <implementation.java class="reference.impl.AComponentImpl"/> <reference name="cReference" autowire="true"/> <reference name="dReference1"/> <reference name="dReference" autowire="true"/> <reference multiplicity="0..n" name="dReferences" autowire="true"/> <reference multiplicity="0..n" name="dReferenceArray" autowire="true"/> <reference multiplicity="0..n" name="dServiceReferences" target="DComponent DComponent1"/> </component> <component name="CComponent"> <implementation.java class="reference.impl.CComponentImpl"/> </component> <component name="DComponent"> <implementation.java class="reference.impl.DComponentImpl"/> </component> <component name="DComponent1"> <implementation.java class="reference.impl.DComponentImpl"/> </component> </composite>

 

Ø         创建接口类

 package reference.lib; public interface AComponent { String fooC(); String fooD(); String fooD1(); String fooMultipleD(); String fooMultipleDArray(); String fooMultipleDServiceRef(); DComponent getDReference(); }

 

 package reference.lib; public interface CComponent { String cFoo(); }

package reference.lib; public interface DComponent { String dFoo(); String getComponentName(); }

 

Ø         创建实现类

package reference.impl; import java.util.Collection; import java.util.List; import org.osoa.sca.ServiceReference; import org.osoa.sca.annotations.Reference; import reference.lib.AComponent; import reference.lib.CComponent; import reference.lib.DComponent; public class AComponentImpl implements AComponent { @Reference protected CComponent cReference; @Reference(required = false) protected DComponent dReference; @Reference(name = "dReferences") public Collection<DComponent> dReferences; @Reference(name = "dReferenceArray") public DComponent[] dReferenceArray; @Reference(name = "dServiceReferences") public List<ServiceReference<DComponent>> dServiceReferences; private DComponent dReference1; @Reference(name = "dReference1") public void setDReference(DComponent dReference) { this.dReference1 = dReference; } public String fooC() { return cReference.cFoo(); } public String fooD1() { return dReference1.dFoo(); } public String fooD() { return dReference.dFoo(); } public String fooMultipleDArray() { StringBuffer str = new StringBuffer(); for (DComponent d : dReferenceArray) { str.append(d.getComponentName()); str.append(','); } if (str.length() > 0) { str.deleteCharAt(str.length() - 1); } return str.toString(); } public String fooMultipleD() { StringBuffer str = new StringBuffer(); for (DComponent d : dReferences) { str.append(d.getComponentName()); str.append(','); } if (str.length() > 0) { str.deleteCharAt(str.length() - 1); } return str.toString(); } public String fooMultipleDServiceRef() { StringBuffer str = new StringBuffer(); for (ServiceReference<DComponent> d : dServiceReferences) { str.append(d.getService().getComponentName()); str.append(','); } if (str.length() > 0) { str.deleteCharAt(str.length() - 1); } return str.toString(); } public DComponent getDReference() { return dReference; } }

package reference.impl; import reference.lib.CComponent; public class CComponentImpl implements CComponent { public String cFoo() { return "CComponent"; } }

package reference.impl; import org.osoa.sca.annotations.ComponentName; import reference.lib.DComponent; public class DComponentImpl implements DComponent { @ComponentName public String name; public String dFoo() { return "DComponent"; } public String getComponentName() { return name; } }

 

Ø         新建测试类

 package test; import org.apache.tuscany.sca.host.embedded.SCADomain; import reference.lib.AComponent; public class TestAutoWireReference { public static void main(String[] args) throws Exception { SCADomain domain = SCADomain.newInstance("AutoWiredReferences.composite"); AComponent acomponent = domain.getService(AComponent.class, "AComponent"); System.out.println("1.cReference-autowire(true):wire cReference to CComponent"); System.out.println(" WIRED COMPONENT NAME: " + acomponent.fooC()); System.out.println("2.dReference-autowire(true):wire dReference to DComponent"); System.out.println(" WIRED COMPONENT NAME: " + acomponent.fooD()); System.out.println("3.dReferences-autowire(true):wire dReference to DComponent and DComponent1"); System.out.println(" WIRED COMPONENT NAME: " + acomponent.fooMultipleD()); System.out.println("4.dReference-autowire(false):not wire dReference to any service"); try{ System.out.println(acomponent.fooD1()); }catch(Exception e){ System.out.println(" nullpointer Exception:"); } System.out.println("5.dReferenceArray-autowire(true):wire dReferenceArray to DComponent and DComponent1"); System.out.println(" WIRED COMPONENT NAME: " + acomponent.fooMultipleDArray()); System.out.println("6.dServiceReferences-autowire(false)-wire(by target):wire dServiceReferences to DComponent and DComponent1"); System.out.println(" WIRED COMPONENT NAME: " + acomponent.fooMultipleDServiceRef()); } }

Ø         运行测试类，结果

Jul 8, 2010 4:37:51 PM org.apache.tuscany.sca.node.impl.NodeImpl <init>

INFO: Creating node: AutoWiredReferences.composite

Jul 8, 2010 4:37:52 PM org.apache.tuscany.sca.node.impl.NodeImpl configureNode

INFO: Loading contribution: file:/D:/eclipse-3.5.2/workspace/reference-autowire/bin/

Jul 8, 2010 4:37:54 PM org.apache.tuscany.sca.assembly.builder.impl.ComponentConfigurationBuilderImpl

WARNING: Component reference multiplicity incompatible with reference multiplicity: Component = AComponent Reference = dReferences

Jul 8, 2010 4:37:54 PM org.apache.tuscany.sca.assembly.builder.impl.ComponentConfigurationBuilderImpl

WARNING: Component reference multiplicity incompatible with reference multiplicity: Component = AComponent Reference = dReferenceArray

Jul 8, 2010 4:37:54 PM org.apache.tuscany.sca.assembly.builder.impl.ComponentConfigurationBuilderImpl

WARNING: Component reference multiplicity incompatible with reference multiplicity: Component = AComponent Reference = dServiceReferences

Jul 8, 2010 4:37:54 PM org.apache.tuscany.sca.assembly.builder.impl.CompositeBindingURIBuilderImpl

WARNING: Component reference multiplicity incompatible with reference multiplicity: Component = AComponent Reference = dReferences

Jul 8, 2010 4:37:54 PM org.apache.tuscany.sca.assembly.builder.impl.CompositeBindingURIBuilderImpl

WARNING: Component reference multiplicity incompatible with reference multiplicity: Component = AComponent Reference = dReferenceArray

Jul 8, 2010 4:37:54 PM org.apache.tuscany.sca.assembly.builder.impl.CompositeBindingURIBuilderImpl

WARNING: Component reference multiplicity incompatible with reference multiplicity: Component = AComponent Reference = dServiceReferences

Jul 8, 2010 4:37:54 PM org.apache.tuscany.sca.assembly.builder.impl.ComponentReferenceWireBuilderImpl

WARNING: No targets for reference: Composite = {http://foo}AutowireReferences Reference = dReference1

Jul 8, 2010 4:37:54 PM org.apache.tuscany.sca.node.impl.NodeImpl start

INFO: Starting node: AutoWiredReferences.composite

1.cReference-autowire(true):wire cReference to CComponent

  WIRED COMPONENT NAME: CComponent

2.dReference-autowire(true):wire dReference to DComponent

  WIRED COMPONENT NAME: DComponent

3.dReferences-autowire(true):wire dReference to DComponent and DComponent1

  WIRED COMPONENT NAME: DComponent,DComponent1

4.dReference-autowire(false):not wire dReference to any service

  nullpointer Exception:

5.dReferenceArray-autowire(true):wire dReferenceArray to DComponent and DComponent1

  WIRED COMPONENT NAME: DComponent,DComponent1

6.dServiceReferences-autowire(false)-wire(by target):wire dServiceReferences to DComponent and DComponent1

  WIRED COMPONENT NAME: DComponent,DComponent1

 

结果中每个case都有说明，就不额外讲了。