在Mule中如何记录http响应而不更改原始输出流

Question

My Mule will do a HTTP call and response to my client, I want to log the HTTP call result, like status code and response body. At first I log the #[payload], but it's a stream, I know <object-to-string-transformer/> works, but I don't want to change the response, so I put the transformer into an enricher, but the result is still changed, why?

My code:

<http:outbound-endpoint exchange-pattern="request-response" address="http://#[payload]" doc:name="Call Service in Pool"/>
<enricher source="#[payload]" target="#[flowVars['responseBody']]" doc:name="Message Enricher">
    <object-to-string-transformer doc:name="Object to String"/>
</enricher>
<logger level="INFO" doc:name="Log Response" message="response, http status: #[message.inboundProperties['http.status']], body: #[flowVars['responseBody']], org: #[payload]"/>

Log output:

org.mule.api.processor.LoggerMessageProcessor: response, http status: 200, body: {"groupId":"group1", "formParam":"null"}, org: org.mule.transport.http.ReleasingInputStream@51dfd9b8

Client receives no body:

HTTP/1.1 200 OK
Content-Type: application/json
Date: Sat, 24 Aug 2013 10:55:49 +0800
Server: Mule EE Core Extensions/3.4.0
X-MULE_SESSION: 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
X-MULE_ENCODING: UTF-8
Transfer-Encoding: chunked
Connection: close

Answer 1

This is the standard behavior of streams: once you consumed it, it's consumed and, unless you reset it, it stays consumed with no more data available.

You can try using mark() before logging then reset() after (in MEL expression components) but there is no guarantee the actual stream implementation produced by Mule supports these methods.

Read the InputStream JavaDoc for more information.

Answer 2

Mule allows you to use Java in the MEL expressions. You could try something like this:

#[String str = message.payloadAs(java.lang.String); java.io.InputStream ins = new java.io.ByteArrayInputStream(str.getBytes()); message.payload = ins; return str;]"