zipkin对于dubbo的支持

对于Web端：
　　1. 需要在applicationContext的头部添加中添加prefix引用：

xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
xsi:schemaLocation="...http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd"

2. 添加dubbo的过滤器（可以和webhttpTracing公用一个Tracing）
 <dubbo:consumer filter="tracing" /> 

3. 在pom中添加dubbo rpc的引用

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>io.zipkin.brave</groupId>
            <artifactId>brave-bom</artifactId>
            <version>${brave.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>y

<dependency>
    <groupId>io.zipkin.brave</groupId>
    <artifactId>brave</artifactId>
</dependency>
<dependency>
    <groupId>io.zipkin.brave</groupId>
    <artifactId>brave-spring-beans</artifactId>
</dependency>

<dependency>
    <groupId>io.zipkin.reporter2</groupId>
    <artifactId>zipkin-sender-okhttp3</artifactId>
</dependency>
<dependency>
    <groupId>io.zipkin.brave</groupId>
    <artifactId>brave-context-log4j12</artifactId>
</dependency>
<dependency>
    <groupId>io.zipkin.brave</groupId>
    <artifactId>brave-instrumentation-spring-web</artifactId>
</dependency>
<dependency>
    <groupId>io.zipkin.brave</groupId>
    <artifactId>brave-instrumentation-spring-webmvc</artifactId>
</dependency>
<dependency>
    <groupId>io.zipkin.brave</groupId>
    <artifactId>brave-instrumentation-dubbo-rpc</artifactId>
</dependency>

在Provider端：
1. applicationContext.xml文件（或者自定义的bean文件）中添加prefix引用以及添加tracing bean：

xmlns:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="...http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.5.xsd

 1 <bean id="tracing" class="brave.spring.beans.TracingFactoryBean">
 2     <property name="localServiceName" value="rpc-double" />
 3     <property name="spanReporter">
 4         <bean class="zipkin2.reporter.beans.AsyncReporterFactoryBean">
 5             <property name="encoder" value="JSON_V2" />
 6             <property name="sender">
 7                 <bean class="zipkin2.reporter.beans.URLConnectionSenderFactoryBean">
 8                 <property name="endpoint" value="http://10.4.120.77:9411/api/v2/spans" />
 9                 </bean>
10             </property>
11             <!-- wait up to half a second for any in-flight spans on close -->
12             <property name="closeTimeout" value="500" />
13         </bean>
14     </property>
15     <property name="propagationFactory">
16         <bean id="propagationFactory" class="brave.propagation.ExtraFieldPropagation"
17             factory-method="newFactory">
18             <constructor-arg index="0">
19                 <util:constant static-field="brave.propagation.B3Propagation.FACTORY" />
20             </constructor-arg>
21             <constructor-arg index="1">
22                 <list>
23                     <value>user-name</value>
24                 </list>
25             </constructor-arg>
26         </bean>
27     </property>
28     <property name="currentTraceContext">
29         <bean class="brave.context.log4j12.MDCCurrentTraceContext"
30             factory-method="create" />
31     </property>
32 </bean>

2. 添加tracing bean

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>io.zipkin.brave</groupId>
            <artifactId>brave-bom</artifactId>
            <version>${brave.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>
<dependency>
    <groupId>io.zipkin.brave</groupId>
    <artifactId>brave</artifactId>
</dependency>
<dependency>
    <groupId>io.zipkin.brave</groupId>
    <artifactId>brave-spring-beans</artifactId>
</dependency>
<dependency>
    <groupId>io.zipkin.reporter2</groupId>
    <artifactId>zipkin-reporter-spring-beans</artifactId>
</dependency>
<dependency>
    <groupId>io.zipkin.reporter2</groupId>
    <artifactId>zipkin-sender-urlconnection</artifactId>
</dependency>
<dependency>
    <groupId>io.zipkin.reporter2</groupId>
    <artifactId>zipkin-sender-okhttp3</artifactId>
</dependency>
<dependency>
    <groupId>io.zipkin.brave</groupId>
    <artifactId>brave-instrumentation-dubbo-rpc</artifactId>
</dependency>
<dependency>
    <groupId>io.zipkin.brave</groupId>
    <artifactId>brave-context-log4j12</artifactId>
</dependency>