SCA概念与应用实践(7.SCA装配模型--7.3 接口 interface)

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7.3. 接口 interface

7.3.1. 解释

Interface定义一个或多个业务功能。这些业务功能通过service来对外提供，通过reference来使用。一个service提供确切唯一的interface的业务功能给其他component使用。每个接口都定义了一个或多个操作（operation），每个operation都有0个或1个请求（输入）消息和0个或1个响应（输出）消息。请求和响应消息可以是简单类型，如string 值，也可以是复杂类型。

Tuscany中service的interface支持 JavaInterface和WSDLInterface。

查看Restaurant2.composite，RestaurantService定义，

<sca:service name="RestaurantService">

<sca:interface.java interface="restaurant2.api.RestaurantService"/>

</sca:service>

这里使用的是java interface。Interface的值是service类的全限定名。

7.3.2. 替换service的interface为WSDL interface

Ø 生成wsdl文件

首先使用interface restaurant2.api.RestaurantService生成WSDL文件restaurant2.wsdl

<?xml version="1.0" encoding="UTF-8"?><wsdl:definitions name="RestaurantServiceService" targetNamespace="http://api.restaurant2/" xmlns:tns="http://api.restaurant2/" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:SOAP="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:SOAP11="http://schemas.xmlsoap.org/wsdl/soap/"> <wsdl:types> <xs:schema attributeFormDefault="qualified" elementFormDefault="unqualified" targetNamespace="http://api.restaurant2/" xmlns:tns="http://api.restaurant2/" xmlns:xs="http://www.w3.org/2001/XMLSchema"><xs:element name="getMenus"><xs:complexType/></xs:element><xs:element name="getMenusResponse"><xs:complexType><xs:sequence><xs:element maxOccurs="unbounded" minOccurs="0" name="return" nillable="true" type="tns:menu"/></xs:sequence></xs:complexType></xs:element><xs:element name="getBillResponse"><xs:complexType><xs:sequence><xs:element minOccurs="0" name="return" type="xs:double"/></xs:sequence></xs:complexType></xs:element><xs:element name="getBill"><xs:complexType><xs:sequence><xs:element minOccurs="0" name="arg0" nillable="true" type="tns:menu"/></xs:sequence></xs:complexType></xs:element><xs:complexType name="menu"><xs:sequence><xs:element minOccurs="0" name="details" type="xs:string"/><xs:element name="id" type="xs:int"/></xs:sequence></xs:complexType><xs:complexType final="#all" name="menuArray"><xs:sequence><xs:element maxOccurs="unbounded" minOccurs="0" name="item" nillable="true" type="tns:menu"/></xs:sequence></xs:complexType></xs:schema> </wsdl:types> <wsdl:message name="getMenus"> <wsdl:part name="getMenus" element="tns:getMenus"> </wsdl:part> </wsdl:message> <wsdl:message name="getMenusResponse"> <wsdl:part name="getMenusResponse" element="tns:getMenusResponse"> </wsdl:part> </wsdl:message> <wsdl:message name="getBillResponse"> <wsdl:part name="getBillResponse" element="tns:getBillResponse"> </wsdl:part> </wsdl:message> <wsdl:message name="getBill"> <wsdl:part name="getBill" element="tns:getBill"> </wsdl:part> </wsdl:message> <wsdl:portType name="RestaurantService"> <wsdl:operation name="getBill"> <wsdl:input message="tns:getBill"> </wsdl:input> <wsdl:output message="tns:getBillResponse"> </wsdl:output> </wsdl:operation> <wsdl:operation name="getMenus"> <wsdl:input message="tns:getMenus"> </wsdl:input> <wsdl:output message="tns:getMenusResponse"> </wsdl:output> </wsdl:operation> </wsdl:portType> <wsdl:binding name="RestaurantServiceBinding" type="tns:RestaurantService"> <SOAP:binding style="document" mce_style="document" transport="http://schemas.xmlsoap.org/soap/http"/> <wsdl:operation name="getBill"> <SOAP:operation/> <wsdl:input> <SOAP:body use="literal"/> </wsdl:input> <wsdl:output> <SOAP:body use="literal"/> </wsdl:output> </wsdl:operation> <wsdl:operation name="getMenus"> <SOAP:operation/> <wsdl:input> <SOAP:body use="literal"/> </wsdl:input> <wsdl:output> <SOAP:body use="literal"/> </wsdl:output> </wsdl:operation> </wsdl:binding> <wsdl:service name="RestaurantServiceService"> <wsdl:port name="RestaurantServicePort" binding="tns:RestaurantServiceBinding"> <SOAP:address location="http://localhost:8085/RestaurantService"/> </wsdl:port> </wsdl:service></wsdl:definitions>

Ø 删除RestaurantService的interface，然后添加WSDLPortType

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图7_3_1

Ø 并设置peroperties

Interface: http://api.restaurant2/#wsdl.interface(RestaurantService)

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图7_3_2

Ø 给RestaurantService添加binding

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图7_3_3

Ø 然后设置properties

Uri：http://localhost:8085/RestaurantService

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图7_3_4

现在的RestaurantServiceComponent的定义为

<sca:component name="RestaurantServiceComponent">

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

<sca:reference name="menuService"/>

<sca:reference name="billService"/>

<sca:service name="RestaurantService">

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

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

<sawsdl:semantic.sawsdl/>

</sca:service>

<sawsdl:semantic.sawsdl/>

</sca:component>

interface – portType/interface

URI地址的格式 <WSDL-namespace-URI>#wsdl.interface(<portTypeOrInterface-name>)

Ø 测试webservice

添加新类RestaurantServiceServer

package test; import org.apache.tuscany.sca.host.embedded.SCADomain; /*** A restaurant service server. Starts up the SCA runtime which will start* listening for Web service requests.*/public class RestaurantServiceServer { public static void main(String[] args) throws Exception { System.out .println("Starting of the SCA Restaurant Application exposed as Web Services..."); SCADomain scaDomain = SCADomain .newInstance("Restaurant2.composite"); System.out.println("... Press Enter to Exit..."); System.in.read(); scaDomain.close(); System.out.println("Exited..."); System.exit(0); }}

运行RestaurantServiceServer

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图7_3_5

使用soapUI测试webservice

使用restaurant2.wsdl创建一个新的project

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图7_3_6

调用getMenu的结果

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图7_3_7

调用getBill的结果

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图7_3_8

7.3.3. 本地和远程接口

通过在java接口类中添加@Remotable来定义为远程接口，否则为本地接口。本地接口的服务只能被在同一个进程中的component所使用。WSDL定义的接口一定是远程的。远程服务接口不能对方法或操作进行重载。

7.3.4. 双向interface

一个业务服务与另一个业务服务的关系经常是peer-to-peer的，在service层面上要求双向依赖。换句话说，一个service既使用某个service提供的服务，同时又为对方提供服务。特别是在基于异步消息而非远程过程调用（RPC）的情况下。双向接口的目的是在SCA中建立点对点双向服务关系。

对于某个特定的接口类型，interface属性中可以可选择性的定义一个回调接口。如果定义了一个回调接口，那么SCA将该接口整体作为一个双向接口

如果一个service使用一个双向interface定义，那么在component的实现中必须实现该接口，并且通过回调接口来与调用服务接口的client进行交互。

如果一个reference使用一个双向interface定义，那么使用该reference的client component的实现会通过该接口来调用service。Client component的实现必须实现该回调接口。回调既能用于远程也能用于本地服务。一个双向服务接口必须要么都为远程的，要么都为本地的。一个双向服务不能同时混用本地服务和远程服务。

7.3.4.1. 使用双向interface的本地service

以TipServiceComponent上的service为例，BillServiceComponent要调用TipServiceComponent的getPriceWithTip来获得加上小费后的账单。前面的例子中，getPriceWithTip会直接返回账单，下面我们把它修改成不直接返回账单，而是利用callback的方式传回账单。我们简单介绍一下这个例子。在实际应用中，很少会在本地service中使用callback。所有的服务都是在同一个进程中，使用callback也没实际作用。

Ø 定义callback的interface

package restaurant2.api;import org.osoa.sca.annotations.Remotable;/** * The callback interface for TipService. */@Remotablepublic interface TipServiceCallback { void receiveResult(double result);}

Ø TipService中声明callback接口，并设置getPriceWithTip为Oneway，没有返回值

package restaurant2.api;import org.osoa.sca.annotations.Callback;import org.osoa.sca.annotations.OneWay;import org.osoa.sca.annotations.Remotable;@Callback(TipServiceCallback.class)@Remotablepublic interface TipService { @OneWay void getPriceWithTip(double price);}

Ø }BillServiceImpl中实现回调接口

package restaurant2.lib;import org.osoa.sca.annotations.Reference;import org.osoa.sca.annotations.Scope;import org.osoa.sca.annotations.Service;import restaurant2.api.BillService;import restaurant2.api.TipService;import restaurant2.api.TipServiceCallback;import restaurant2.api.VatService;@Service(BillService.class)public class BillServiceImpl implements BillService, TipServiceCallback { private VatService vatService; private TipService tipService; private static double priceWithTipRate = -1; @Reference public void setVatService(VatService vatService) { this.vatService = vatService; } @Reference public void setTipService(TipService tipService) { this.tipService = tipService; } public double getBill(double menuPrice) { double pricewithTaxRate = this.vatService.getPriceWithVat(menuPrice);// double priceWithTipRate = // this.tipService.getPriceWithTip(pricewithTaxRate); System.out.println("call tipService on thread " + Thread.currentThread()); this.tipService.getPriceWithTip(pricewithTaxRate); while(priceWithTipRate == -1) System.out.println("waiting for callback ..."); return priceWithTipRate; } public void receiveResult(double result) { try{ System.out.println("receiveResult on thread " + Thread.currentThread()); System.out.println("Result: " + result); System.out.println("Set Result to priceWithTipRate. "); priceWithTipRate = result; }catch(Exception e) { e.printStackTrace(); } }}

Ø TipServiceImpl中添加callback接口的setter方法，并修改getPriceWithTip调用callback

package restaurant2.lib;import org.osoa.sca.annotations.Callback;import org.osoa.sca.annotations.Property;import org.osoa.sca.annotations.Scope;import org.osoa.sca.annotations.Service;import restaurant2.api.TipService;import restaurant2.api.TipServiceCallback;@Scope("COMPOSITE")@Service(TipService.class)public class TipServiceImpl implements TipService { @Property public double tipRate; private TipServiceCallback tipServiceCallback; /** * The setter used by the runtime to set the callback reference * @param tipServiceCallback */ @Callback public void setTipServiceCallback(TipServiceCallback tipServiceCallback) { System.out.println("setTipServiceCallback on thread " + Thread.currentThread()); this.tipServiceCallback = tipServiceCallback; } public TipServiceImpl(){ this.tipRate=10; } public void getPriceWithTip(double price) { //return price * this.tipRate/100 + price; System.out.println("getPriceWithTip on thread " + Thread.currentThread()); // invoke the callback try { //Thread.sleep(100); tipServiceCallback.receiveResult(price * this.tipRate/100 + price); } catch(RuntimeException e) { System.out.println("RuntimeException invoking receiveResult: " + e.toString()); e.printStackTrace(); } catch(Exception e) { System.out.println("Exception invoking receiveResult: " + e.toString()); e.printStackTrace(); } }}

Ø 在Restaurant2.composite中删去TipServiceComponent的service，同时删去相应的wire，在BillServiceComponent的reference上添加target。

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

<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:component name="RestaurantServiceComponent">

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

<sca:reference name="menuService"/>

<sca:reference name="billService"/>

<sca:service name="RestaurantService">

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

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

<sawsdl:semantic.sawsdl/>

</sca:service>

<sawsdl:semantic.sawsdl/>

</sca:component>

<sca:component name="MenuServiceComponent">

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

<sca:service name="MenuService">

<sca:interface.java interface="restaurant2.api.MenuService"/>

</sca:service>

</sca:component>

<sca:component name="BillServiceComponent">

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

<sca:service name="BillService">

<sca:interface.java interface="restaurant2.api.BillService"/>

</sca:service>

<sca:reference name="vatService"/>

<sca:reference name="tipService" target="TipServiceComponent"/>

</sca:component>

<sca:component name="VatServiceComponent">

<tuscany:implementation.script script="restaurant2/lib/VatServiceImpl.js"/>

<sca:service name="VatService">

<sca:interface.java interface="restaurant2.api.VatService"/>

</sca:service>

</sca:component>

<sca:component name="TipServiceComponent">

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

</sca:component>

<sca:wire source="RestaurantServiceComponent/billService" target="BillServiceComponent/BillService"/>

<sca:wire source="BillServiceComponent/vatService" target="VatServiceComponent/VatService"/>

<sca:service name="RestaurantService" promote="RestaurantServiceComponent/RestaurantService"/>

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

</sca:composite>

Ø 运行RestaurantServiceServer

Ø 用soapUI调用webservice

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图7_3_9

Ø Application的输出
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图7_3_10

7.3.4.2. 使用双向interface的远程调用

Ø 新建一个project，叫做Restaurant2Tip

Ø 在项目Restaurant2Tip的src目录下新建SCA Composite Diagram，名字为Restaurant2Tip

Ø 从项目Restaurant2的SCA composite Diagram里删除TipServiceComponent,

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图7_3_11

Ø 在Restaurant2Tip的diagram里新建TipServiceComponent

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图7_3_12

Ø 在TipServiceComponent上添加service, 名字是TipService.

Ø 给service TipService添加Java interface，interface的属性中定义：

Interface：restaurant2.api.TipService

CallbackInterface：restaurant2.api.TipServiceCallback

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图7_3_13

Ø 给service TipService添加binding，设置binding的uri为http://localhost:8085/TipServiceComponent

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图7_3_14

Ø 复制TipService.java TipServiceCallback.java 和TipServiceImpl.java到项目Restaurant2Tip

Ø 新建测试类TipServiceServer.java

package test; import org.apache.tuscany.sca.host.embedded.SCADomain; /*** A restaurant tip service server. Starts up the SCA runtime which will start* listening for Web service requests.*/public class TipServiceServer { public static void main(String[] args) throws Exception { System.out .println("Starting of the SCA Restaurant Tip Application exposed as Web Services..."); SCADomain scaDomain = SCADomain .newInstance("Restaurant2Tip.composite"); System.out.println("... Press Enter to Exit..."); System.in.read(); scaDomain.close(); System.out.println("Exited..."); System.exit(0); }}

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图7_3_15

Ø 在Restaurant2的component BillServiceComponent的reference tipService上添加java interface，并设置属性为：

Interface：restaurant2.api.TipService

CallBack Interface：restaurant2.api.TipServiceCallback

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图7_3_16

Ø 在Restaurant2的component BillServiceComponent的reference tipService上添加binding，并设置uri为http://localhost:8086/TipServiceComponent

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图7_3_17

Ø 首先运行Restaurant2Tip下的TipServiceServer

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图7_3_18

Ø 然后运行Restaurant2下面的RestaurantServiceServer

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图7_3_19

Ø 使用soapUI调用Restaurant2的web service

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图7_3_20

Ø 在Restaurant2Tip的TipServiceServer的Console里输出

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图7_3_21

Ø 在Restaurant2的RestaurantServiceServer的Console里输出

Starting of the SCA Restaurant Application exposed as Web Services...

Jun 25, 2010 1:12:32 PM org.apache.tuscany.sca.node.impl.NodeImpl <init>

INFO: Creating node: Restaurant2.composite

Jun 25, 2010 1:12:33 PM org.apache.tuscany.sca.node.impl.NodeImpl configureNode

INFO: Loading contribution: file:/D:/eclipse-3.5.2/workspace/Restaurant2/bin/

Jun 25, 2010 1:12:34 PM

…………

http://quzhengxi:8087/TipServiceComponentCB

... Press Enter to Exit...

call tipService on thread Thread[Thread-9,5,main]

waiting for callback ...

…………

waiting for callback ...

receiveResult on thread Thread[Thread-11,5,main]

Result: 42.35

Set Result to priceWithTipRate.

从输出中可以看到，BillService首先调用TipService的getPriceWithTip，然后等待TipService调用callback来设置priceWithTipRate的值，当BillService获得priceWithTipRate的值后，返回给上一层调用。

7.3.5. 会话接口（conversational interfaces）

7.3.5.1. 解释

很多时候服务不能定义成一个方法单独完成，可能调用一系列的方法。SCA把这一系列调用称为conversation。如果service使用了双向接口，那么会话同时包含调用和回调。

SCA使用使用会话标识来管理会话服务，会话标识来自于应用数据之外的通讯数据中。SCA的runtime依赖binding的支持来会自动管理会话。

支持会话的很重要的目的是管理应用的状态数据。看上面的例子，BillService使用回调方法从TipService来获得计算后的priceWithTipRate。在类BillServiceImpl里我们定义的变量priceWithTipRate是static的。这个在实际应用中是不可行的，如果他是static的，当有两个以上账单结帐时就会出现混乱，即使修改一下，也无法解决同时结帐的问题。

如果去掉static，计算账单的进程那么就无法获得通过callback写入的priceWithTipRate值。下面我们看一下去掉static后的结果。

7.3.5.2. 演示需要使用conversation的地方

Ø 修改BillServiceImpl，（1）删掉static，（2）删掉输出” waiting for callback”,这个是为了比较容易看到输出。

package restaurant2.lib;…public class BillServiceImpl implements BillService, TipServiceCallback { … private double priceWithTipRate = -1; …… public double getBill(double menuPrice) { …… while(priceWithTipRate == -1){} //System.out.println("waiting for callback ..."); return priceWithTipRate; }……}

Ø 运行TipServiceServer和RestaurantServiceServer，然后用soapUI调用ws getBill，无法获得结果。

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图7_3_22

Ø 查看RestaurantServiceServer的console

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图7_3_23

在这里你会看到，call tipService的进程和收到结果的进程是不同的，Thread-9调用this.tipService.getPriceWithTip(pricewithTaxRate); 后一直在等待结果，但是TipService把结果发给了另外一个进程thread-11，所以thread-9一直在等待。

7.3.5.3. 使用conversation解决上面问题

Conversation的定义就是为了解决这个问题。Conversation通过annotation @Conversational 来定义。这个例子中，是个双向的interface，所以调用和回调都要定义conversation。

Ø 修改TipService和，Restaurant2 和Restaurant2Tip里的都要修改

package restaurant2.api;import org.osoa.sca.annotations.Callback;import org.osoa.sca.annotations.Conversational;import org.osoa.sca.annotations.OneWay;import org.osoa.sca.annotations.Remotable;@Callback(TipServiceCallback.class)@Remotable@onversationalpublic interface TipService { @OneWay void getPriceWithTip(double price);}

package restaurant2.api;import org.osoa.sca.annotations.Conversational;import org.osoa.sca.annotations.Remotable;/** * The callback interface for TipService. */@Remotable@Conversationalpublic interface TipServiceCallback { void receiveResult(double result);}

Ø 修改TipServiceImpl，

这两个东西

@Scope("CONVERSATION")

@ConversationAttributes(maxAge="1 seconds")，conversation后面节会再说。

package restaurant2.lib; import org.osoa.sca.annotations.Callback;import org.osoa.sca.annotations.ConversationAttributes;import org.osoa.sca.annotations.Property;import org.osoa.sca.annotations.Scope;import org.osoa.sca.annotations.Service;import restaurant2.api.TipService;import restaurant2.api.TipServiceCallback; @Service(TipService.class)@Scope("CONVERSATION")@ConversationAttributes(maxAge="1 seconds")public class TipServiceImpl implements TipService { @Property public double tipRate; private TipServiceCallback tipServiceCallback; /** * The setter used by the runtime to set the callback reference * @param tipServiceCallback */ @Callback public void setTipServiceCallback(TipServiceCallback tipServiceCallback) { System.out.println("setTipServiceCallback on thread " + Thread.currentThread()); this.tipServiceCallback = tipServiceCallback; } public TipServiceImpl(){ this.tipRate=10; } public void getPriceWithTip(double price) { //return price * this.tipRate/100 + price; System.out.println("getPriceWithTip on thread " + Thread.currentThread()); // invoke the callback try { //Thread.sleep(100); tipServiceCallback.receiveResult(price * this.tipRate/100 + price); } catch(RuntimeException e) { System.out.println("RuntimeException invoking receiveResult: " + e.toString()); e.printStackTrace(); } catch(Exception e) { System.out.println("Exception invoking receiveResult: " + e.toString()); e.printStackTrace(); } }}

Ø 修改BillServiceImpl

这两项@Scope("CONVERSATION")

@ConversationAttributes(maxAge="10 minutes",

maxIdleTime="5 minutes")

注意这里priceWithTipRate不是static的。

package restaurant2.lib; import org.osoa.sca.annotations.ConversationAttributes;import org.osoa.sca.annotations.Reference;import org.osoa.sca.annotations.Scope;import org.osoa.sca.annotations.Service;import restaurant2.api.BillService;import restaurant2.api.TipService;import restaurant2.api.TipServiceCallback;import restaurant2.api.VatService; @Service(BillService.class)@Scope("CONVERSATION")@ConversationAttributes(maxAge="10 minutes", maxIdleTime="5 minutes")public class BillServiceImpl implements BillService, TipServiceCallback { private VatService vatService; private TipService tipService; private double priceWithTipRate = -1; @Reference public void setVatService(VatService vatService) { this.vatService = vatService; } @Reference public void setTipService(TipService tipService) { this.tipService = tipService; } public double getBill(double menuPrice) { double pricewithTaxRate = this.vatService.getPriceWithVat(menuPrice);// double priceWithTipRate = // this.tipService.getPriceWithTip(pricewithTaxRate); System.out.println("call tipService on thread " + Thread.currentThread()); this.tipService.getPriceWithTip(pricewithTaxRate); while(priceWithTipRate == -1) System.out.println("waiting for callback ..."); return priceWithTipRate; } public void receiveResult(double result) {try{System.out.println("receiveResult on thread " + Thread.currentThread()); System.out.println("Result: " + result); System.out.println("Set Result to priceWithTipRate. "); priceWithTipRate = result;}catch(Exception e){e.printStackTrace();}}}

Ø 下面再运行TipServiceServer和RestaurantServiceServer，然后用soapUI调用ws getBill，成功获得结果。

Ø 查看RestaurantServiceServer的console的输出，虽然call tipService的进程和收到结果的进程是不同的，但调用的进程后来可以获得结果。

call tipService on thread Thread[Thread-9,5,main]

waiting for callback ...

......

waiting for callback ...

receiveResult on thread Thread[Thread-11,5,main]

waiting for callback ...

......

waiting for callback ...

Result: 42.35

Set Result to priceWithTipRate.