WSO2 MI 4.1.0移除DSS输出XML声明标签及解决迭代问题

我通过DSS从数据库获取数据并返回XML格式结果，但流程无法进入Iterate中介器。移除XML声明标签<?xml version='1.0' encoding='UTF-8'?>后，在线XPath工具能正常生成表达式。请问是否必须移除该标签？如果需要，在WSO2 MI 4.1.0中该如何操作？

数据库调用示例输出 #

<?xml version='1.0' encoding='utf-8'?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
  <soapenv:Body>
    <Entries xmlns="TotscoDS">
      <statusCodePresent>429
      </statusCodePresent>
      <statusCodePresent>429
      </statusCodePresent>
      <statusCodePresent>429
      </statusCodePresent>
      <statusCodePresent>429
      </statusCodePresent>
      <statusCodePresent>429
      </statusCodePresent>
    </Entries>
  </soapenv:Body>
</soapenv:Envelope>

当前序列代码 #

<payloadFactory media-type="xml">
<format>
<getStates>
<msID>$1</msID>
</getStates>
</format>
<args>
<arg evaluator="xml" expression="$ctx:MI_ID"/>
</args>
</payloadFactory>
<property name="messageType" scope="axis2" type="STRING" value="text/xml"/>
<header name="Action" scope="default" value="retrieveStateDetails"/>
<call>
<endpoint key="TotscoEP" />
</call>
<log level="full" />
<iterate expression="//Entries" xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
<target>
<sequence>
<property expression="//statusCodePresent/text()" name="statusCodePresent" scope="default" type="STRING"/>  
<log level="custom">
<property expression="fn:concat($ctx:HUBMessageID,' : StatusCode = ',$ctx:statusCodePresent)" name="Message"/>
</log>
<filter regex="false" source="boolean(get-property('statusCodePresent'))">
<then>
<log level="custom">
<property expression="fn:concat($ctx:HUBMessageID,' : No Status Code from RCP')" name="Message"/>
</log>

</then>
<else/>                                                                 
</filter>
</sequence>
</target>
</iterate>

1. XML声明标签并非必须移除 #

问题核心不是XML声明，而是命名空间未正确处理。返回的<Entries>节点属于TotscoDS命名空间，而你的Iterate表达式//Entries未指定该命名空间，导致XPath无法匹配目标节点，流程因此无法进入Iterate中介器。

2. 正确处理命名空间的Iterate配置 #

修改Iterate中介器，添加TotscoDS命名空间声明，并在XPath表达式中使用对应前缀：

<iterate expression="//ts:Entries" xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ts="TotscoDS">
<target>
<sequence>
<!-- 获取statusCodePresent时同样需要指定命名空间 -->
<property expression="//ts:statusCodePresent/text()" name="statusCodePresent" scope="default" type="STRING"/>  
<log level="custom">
<property expression="fn:concat($ctx:HUBMessageID,' : StatusCode = ',$ctx:statusCodePresent)" name="Message"/>
</log>
<filter regex="false" source="boolean(get-property('statusCodePresent'))">
<then>
<log level="custom">
<property expression="fn:concat($ctx:HUBMessageID,' : No Status Code from RCP')" name="Message"/>
</log>

</then>
<else/>                                                                 
</filter>
</sequence>
</target>
</iterate>

3. 若确需移除XML声明的操作方法 #

如果因特殊需求必须移除XML声明，可在WSO2 MI 4.1.0中通过以下两种方式实现：

方式一：使用PayloadFactory重构Payload #

在Call中介器之后，用PayloadFactory重新生成不含XML声明的XML内容：

<call>
<endpoint key="TotscoEP" />
</call>
<payloadFactory media-type="xml">
<format>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
  <soapenv:Body>
    <Entries xmlns="TotscoDS">
      <statusCodePresent>$1</statusCodePresent>
      <!-- 按需重复节点，若节点数量不固定建议用方式二 -->
    </Entries>
  </soapenv:Body>
</soapenv:Envelope>
</format>
<args>
<arg evaluator="xml" expression="//ts:statusCodePresent/text()" xmlns:ts="TotscoDS"/>
</args>
</payloadFactory>

方式二：使用Script中介器修改消息内容 #

通过Groovy脚本直接移除XML声明：

<call>
<endpoint key="TotscoEP" />
</call>
<script language="groovy"><![CDATA[
def payload = mc.getPayloadXML().toString();
// 匹配并移除XML声明部分
def cleanedPayload = payload.replaceFirst(/<\?xml[^>]+\?>/, "");
mc.setPayloadXML(cleanedPayload);
]]></script>

内容的提问来源于stack exchange，提问作者Sumathi M