ESB學(xué)習(xí)筆記（Spring Integration實戰(zhàn)）

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2009-11-23 來源：網(wǎng)絡(luò)

介紹
Spring Integration是Spring公司的一套ESB框架。
前面ESB介紹中我也做了一定了解。我們來看一下它主要做什么的。
Spring Integration is motivated by the following goals:

Provide a simple model for implementing complex enterprise integration solutions.(暫時相信它吧，誰讓它搞個Spring框架，的確給人方便一把。)
Facilitate asynchronous, message-driven behavior within a Spring-based application.(這個不談，Spring框架就是它玩的。再說這一點與它競爭只有Mule啦。)
Promote intuitive, incremental adoption for existing Spring users. (也暫時相信它，別人都只說給用戶提升。)

Spring Integration is guided by the following principles:

Components should be loosely coupled for modularity and testability.（松耦合，好像很早很早就聽說過。像做夢一樣）
The framework should enforce separation of concerns between business logic and integration logic.（分開程度要取決業(yè)務(wù)吧。）
Extension points should be abstract in nature but within well-defined boundaries to promote reuse and portability.（美妙現(xiàn)實世界產(chǎn)品）

源碼下載打開它的網(wǎng)頁，http://www./spring-integration
主頁上也沒有東東，但有個下源代碼的地方，svn開工啦。
　

Java代碼

svn co https://src./svn/spring-integration/trunk springintegration

svn co https://src./svn/spring-integration/trunk  springintegration

下載完后，進(jìn)入build-spring-integration目錄執(zhí)行ant.完成后，導(dǎo)入到Eclipse中。
導(dǎo)入項目會有很多，先添加時會有報錯。這里需要添加一個變量。
IVY_CACHE＝<checkout-dir>/ivy-cache/repository

這里要注意的事，也是我遇到問題。執(zhí)行ant時，他會去下載lvy，如果你本身在%ANT_HOME%\lib里有l(wèi)vy.jar包，由于我暫時找不到如何處理，我就直接將Ant中的jar刪除掉后就沒有問題。
另外在ant過程中，測試步驟可能會在file模塊中出現(xiàn)問題，可以將相關(guān)test類中代碼注釋掉。

　

HelloWorld源碼分析在samples項目中，打開helloworld包里面有三個文件。
　

Java代碼

package org.springframework.integration.samples.helloworld;
/**
* @author Mark Fisher
*/
public class HelloService {
public String sayHello(String name) {
return "Hello " + name;
}
}

package org.springframework.integration.samples.helloworld;

/**
 * @author Mark Fisher
 */
public class HelloService {

	public String sayHello(String name) {
		return "Hello " + name;
	}

}

helloworldDemo.xml
　

Xml代碼

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www./schema/integration"
xmlns:xsi="http://www./2001/XMLSchema-instance"
xmlns:beans="http://www./schema/beans"
xsi:schemaLocation="http://www./schema/beans
http://www./schema/beans/spring-beans-2.5.xsd
http://www./schema/integration
http://www./schema/integration/spring-integration-1.0.xsd">
<channel id="inputChannel"/>
<channel id="outputChannel">
<queue capacity="10"/>
</channel>
<service-activator input-channel="inputChannel"
output-channel="outputChannel"
ref="helloService"
method="sayHello"/>
<beans:bean id="helloService" class="org.springframework.integration.samples.helloworld.HelloService"/>
</beans:beans>

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www./schema/integration"
	xmlns:xsi="http://www./2001/XMLSchema-instance"
	xmlns:beans="http://www./schema/beans"
	xsi:schemaLocation="http://www./schema/beans
			http://www./schema/beans/spring-beans-2.5.xsd
			http://www./schema/integration
			http://www./schema/integration/spring-integration-1.0.xsd">

	<channel id="inputChannel"/>

	<channel id="outputChannel">
		<queue capacity="10"/>
	</channel>

	<service-activator input-channel="inputChannel"
	                   output-channel="outputChannel"
	                   ref="helloService"
	                   method="sayHello"/>

	<beans:bean id="helloService" class="org.springframework.integration.samples.helloworld.HelloService"/>
</beans:beans>

HelloWorldDemo.java
　

Java代碼

package org.springframework.integration.samples.helloworld;
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.integration.channel.BeanFactoryChannelResolver;
import org.springframework.integration.channel.ChannelResolver;
import org.springframework.integration.channel.PollableChannel;
import org.springframework.integration.core.MessageChannel;
import org.springframework.integration.message.StringMessage;
/**
* Demonstrates a basic message endpoint.
*
* @author Mark Fisher
*/
public class HelloWorldDemo {
public static void main(String[] args) {
AbstractApplicationContext context = new ClassPathXmlApplicationContext("helloWorldDemo.xml", HelloWorldDemo.class);
ChannelResolver channelResolver = new BeanFactoryChannelResolver(context);
MessageChannel inputChannel = channelResolver.resolveChannelName("inputChannel");
PollableChannel outputChannel = (PollableChannel) channelResolver.resolveChannelName("outputChannel");
inputChannel.send(new StringMessage("World"));
System.out.println(outputChannel.receive(0).getPayload());
context.stop();
}
}

package org.springframework.integration.samples.helloworld;

import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.integration.channel.BeanFactoryChannelResolver;
import org.springframework.integration.channel.ChannelResolver;
import org.springframework.integration.channel.PollableChannel;
import org.springframework.integration.core.MessageChannel;
import org.springframework.integration.message.StringMessage;

/**
 * Demonstrates a basic message endpoint. 
 * 
 * @author Mark Fisher
 */
public class HelloWorldDemo {

	public static void main(String[] args) {
		AbstractApplicationContext context = new ClassPathXmlApplicationContext("helloWorldDemo.xml", HelloWorldDemo.class);
		ChannelResolver channelResolver = new BeanFactoryChannelResolver(context);
		MessageChannel inputChannel = channelResolver.resolveChannelName("inputChannel");
		PollableChannel outputChannel = (PollableChannel) channelResolver.resolveChannelName("outputChannel");
		inputChannel.send(new StringMessage("World"));
		System.out.println(outputChannel.receive(0).getPayload());
		context.stop();
	}

}

Cafe源碼分析 Cafe示例描述的是星巴克的訂單處理故事。
其示例描述在：http://www./ramblings/18_starbucks.html
這里簡單描述一下，以免大家看英文太累
文章講在星巴克喝咖啡時，收銀員可能只有一個，而沖咖啡員工會有多個，如何讓收銀員產(chǎn)生訂單異步發(fā)送給沖咖啡員工。并且沖咖啡員工可能是競爭上崗的，就當(dāng)他們是計件工吧。
這里要考慮問題：
1，沖咖啡員工使用不同設(shè)備，不同咖啡沖調(diào)時間可能不同?！?nbsp;
2，沖咖啡員工可能會將相同類型的咖啡同時一起沖調(diào)。
星巴克如何處理這個問題？
就當(dāng)他解決了這個問題，它是如何把每個咖啡又送回給每個客戶呢？當(dāng)然，星巴克采用“標(biāo)識關(guān)系模式”，將每個咖啡杯上標(biāo)上名稱，并通過叫喊方式。
但并不是每天都是美好的，總有出錯的時候。例如，收銀員無法支付？沖調(diào)一杯你不喜歡的咖啡，你要換一杯？沖咖啡的設(shè)備壞了，星巴克要退你錢...這些異常情況如何處理。
因此就會有以下三種方式異常處理：
1,關(guān)閉交易，什么都不做。
2,重做，重新發(fā)起行為。
3,修正行為,相當(dāng)于退錢這種行為。
因此，這里這篇文章后面討論一下兩階段提交為什么不適合星巴克，如果你讓收銀員、沖咖啡員工，買單的人需要在一個“事務(wù)”中，交易所有完成后，再進(jìn)行下一個業(yè)務(wù)。估計星巴克會馬上倒閉啦。因此星巴克采用“Conversation pattern”模式。

好啦，業(yè)務(wù)了解清楚，我們再來看一下完整XML文件。在這里我沒有采用示例詳細(xì)的xml方式，而沒有采用annotation方式。
　

以下是參考文檔中的示例描述圖：

CafeDemo代碼創(chuàng)建了訂單。這家咖啡店有兩種飲料，一種是熱的，一種是冷的，消息將這訂單包裝到一個"orders"的channel（頻道）。一個endpoint偵聽到訂單頻道并根據(jù)訂單情況進(jìn)行分開處理。

完成分開處理后，程序交給DrinksRouter經(jīng)過drink頻道。而DrinkRouter一個職責(zé)就是將訂單內(nèi)容中的熱咖啡和冷咖啡交給不同的channel處理。

　

Xml代碼

<gateway id="cafe" service-interface="org.springframework.integration.samples.cafe.Cafe"/>

	<gateway id="cafe" service-interface="org.springframework.integration.samples.cafe.Cafe"/>

這里Gateway主要是根據(jù)接口生成代理類。

　

Java代碼

Cafe cafe = (Cafe) context.getBean("cafe");
DrinkOrder order = new DrinkOrder();
Drink hotDoubleLatte = new Drink(DrinkType.LATTE, 2, false);
Drink icedTripleMocha = new Drink(DrinkType.MOCHA, 3, true);
order.addDrink(hotDoubleLatte);
order.addDrink(icedTripleMocha);
for (int i = 0; i < 100; i++) {
cafe.placeOrder(order);
}

Cafe cafe = (Cafe) context.getBean("cafe");
                DrinkOrder order = new DrinkOrder();
                Drink hotDoubleLatte = new Drink(DrinkType.LATTE, 2, false);
                Drink icedTripleMocha = new Drink(DrinkType.MOCHA, 3, true);
                order.addDrink(hotDoubleLatte);
                order.addDrink(icedTripleMocha);
                for (int i = 0; i < 100; i++) {
                        cafe.placeOrder(order);
                }

Java代碼

@MessageEndpoint(input="orders", output="drinks")
public class OrderSplitter {
@Splitter
public List<Drink> split(Message<DrinkOrder> orderMessage) {
return orderMessage.getPayload().getDrinks();
}
}

@MessageEndpoint(input="orders", output="drinks")
public class OrderSplitter {

        @Splitter
        public List<Drink> split(Message<DrinkOrder> orderMessage) {
                return orderMessage.getPayload().getDrinks();
        }

}

Java代碼

@MessageEndpoint(input="drinks")
public class DrinkRouter {
@Router
public String resolveDrinkChannel(Drink drink) {
return (drink.isIced()) ? "coldDrinks" : "hotDrinks";
}
}

@MessageEndpoint(input="drinks")
public class DrinkRouter {

        @Router
        public String resolveDrinkChannel(Drink drink) {
                return (drink.isIced()) ? "coldDrinks" : "hotDrinks";
        }

}

Xml代碼

<handler-endpoint handler="coldBarista" input-channel="coldDrinks"
method="prepareColdDrink">
</handler-endpoint>
<handler-endpoint handler="hotBarista" input-channel="hotDrinks"
method="prepareHotDrink">
</handler-endpoint>

<handler-endpoint handler="coldBarista" input-channel="coldDrinks"
        method="prepareColdDrink">
</handler-endpoint>

<handler-endpoint handler="hotBarista" input-channel="hotDrinks"
        method="prepareHotDrink">
</handler-endpoint>

Java代碼

public void prepareColdDrink(Message<Drink> drinkMessage) {
Drink drink = drinkMessage.getPayload();
//no changes to the rest of the code
}

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ESB學(xué)習(xí)筆記（Spring Integration實戰(zhàn)）