Mule 4接收multipart/mixed payload为空及边界缺失问题排查

背景 #

我需要向外部API发送multipart/mixed请求，因此搭建了一个Mule 4流，配置端点接收对应格式的Payload（匹配Postman中的请求内容），但遇到Payload为空和边界缺失的错误。使用的Mule runtime版本为4.4.0-20211227。

Mule流XML代码 #

<?xml version="1.0" encoding="UTF-8"?>
<mule xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation" xmlns:ee="http://www.mulesoft.org/schema/mule/ee/core" xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd http://www.mulesoft.org/schema/mule/ee/core http://www.mulesoft.org/schema/mule/ee/core/current/mule-ee.xsd">
   <http:listener-config name="HTTP_Listener_config" doc:name="HTTP_Listener_config"  doc:id="d8e92a34-d34d-4e1a-abec-7405b9010241">
      <http:listener-connection host="0.0.0.0" port="8081" />
   </http:listener-config>
   <flow name="testmultipart-flow" doc:id="d8e92a34-d34d-4e1a-bce3-7405b9010241">
      <http:listener doc:name="Listener" doc:id="88476dbb-04af-429d-83f3-20714be8d406" config-ref="HTTP_Listener_config" path="/multi" outputMimeType="multipart/mixed; boundary=batch" />
      <logger level="INFO" doc:name="Logger" doc:id="ccde0f6d-cc70-4b05-a68c-60f644381b1e" message="Payload: #[payload]" />
      <ee:transform doc:name="Multipart payload" doc:id="bfeeab27-6f01-4ea1-a46a-1a65c5aa0021">
         <ee:message>
            <ee:set-payload><![CDATA[%dw 2.0
output application/json
---
payload]]></ee:set-payload>
         </ee:message>
      </ee:transform>
   </flow>
</mule>

发起请求的Curl命令 #

curl --location 'http://0.0.0.0:8081/multi/' \
--header 'Content-Type: multipart/mixed; boundary=batch' \
--header 'Authorization: Basic dXNlcm5hbWU6cGFzc3dvcmQ=' \
--data '--batch
Content-Type: application/http
Content-Transfer-Encoding: binary

GET TDTREESET?$filter=(Field1%20eq%20'\''213123'\'')&format=xml HTTP/1.1

--batch-'

问题现象 #

• 请求发起后，Mule流接收的Payload为空，调试模式中无Payload内容
• 调试信息：

payload =
^mediaType = multipart/mixed; charset=UTF-8; boundary=batch

• 流执行结束时的错误：

"javax.mail.internet.ParseException - Missing start boundary
javax.mail.internet.ParseException: Missing start boundary...

疑问 #

1. 如何在Mule流中获取请求发送的原始文本Payload？
2. 已在Listener中设置边界为batch，为何仍会出现边界缺失的错误？

内容的提问来源于stack exchange，提问作者Dan