multipart request not working as expected for spring integration

Question

I have two rest services and a Listener

1. Service A
   2. Service B
   3. Listener L1

---

• Step 1 - Listener L1 reads a file from local and send the multivalue map to service A. Service A retrieve some document from database and returns it as bytes to Listener L1.
  Step 2 - Listener L1 then sends another multivalue Map to Service B and saves the doc.

---

Step 1 is working as expected using MultiValueMap where as when I am trying to send the document bytes to Service B using same procedure During Step 2 - I'm getting Could not write request: no suitable HttpMessageConverter found for request type [org.springframework.util.LinkedMultiValueMap] and content type [application/octet-stream] . I'm following the same procedure but still getting the issue.

Please find below the code samples and let me know how to fix this issue.

Listener1.java

public Message<?> processJMSReqMsqAndSendToRest1(String message) throws Exception {
        MultiValueMap<String, Object> mainMap = new LinkedMultiValueMap<String, Object>();
        Map<String, String> secondaryMap = new HashMap<String, String>();
        secondaryMap.put("key1", "value1");
        secondaryMap.put("key2", "value2");
        secondaryMap.put("key3", "value3");
        byte[] messageBytes = message.getBytes();
        File newFile = new File("D:\\Temp\\temp.jpg");
        InputStream is = new FileInputStream(newFile);
        byte[] fileBytes = IOUtils.toByteArray(is);
        is.close();
        mainMap.add("metaData", secondaryMap);
        mainMap.add("messageBytes", messageBytes );
        Message<?> message1 = MessageBuilder.withPayload(mainMap).build();
        return message1;
    }


public Message<?> processRest1AndSendToRest2(Message<?> obj)  throws Exception{
    byte[] docBytes = (byte[])obj.getPayload();
    MultiValueMap<String, Object> mainMap = new LinkedMultiValueMap<String, Object>();
    Map<String, String> secondaryMap = new HashMap<String, String>();
    secondaryMap.put("key1", "value1");
    secondaryMap.put("key2", "value2");
    secondaryMap.put("key3", "value3");
    mainMap.add("metaData", secondaryMap);
    mainMap.add("messageBytes", docBytes);
    Message<?> message1 = MessageBuilder.withPayload(mainMap).build();
    return message1;

}

Spring Integration xml

<int-http:outbound-gateway
        id="docServiceOutBoundGateway" request-channel="docMetaDataIn"
        http-method="POST" url="http://localhost:8030/getDocument"
        expected-response-type="[B" reply-channel="sourceDocumentOutLv1">
    </int-http:outbound-gateway>

    <int:service-activator
        input-channel="sourceDocumentOutLv1"
        ref="docConversionOrchestratorImpl" method="processRest1AndSendToRest2"
        output-channel="sourceDocumentOutLv2" />

    <int-http:outbound-gateway  request-channel="sourceDocumentOutLv2"
            http-method="POST" url="http://localhost:8030/sendDocument"
            encode-uri="false"
            expected-response-type="java.lang.String" reply-channel="processedDocOutLv1">

    </int-http:outbound-gateway>

---

Service A:

@RequestMapping(value = "/getDocument", method = RequestMethod.POST)
    @ResponseBody
    public byte[] testRest1(@RequestPart("metaData")Map<String,String> metaData,@RequestPart("messageBytes")byte[] messageBytes) {
byte[] r2  = //get doc from database as bytes
        return r2;
    }

---

Service B:

@RequestMapping(value = "/sendDocument", method = RequestMethod.POST)
    @ResponseBody
    public String tesMySql1(@RequestPart("metaData")Map<String,String> metaData,@RequestPart("messageBytes")byte[] messageBytes) {

            return  "working";
    }

---

I have tried with sending it directly through rest template through java, that is working fine. But I want the structure to be consistent and be done through spring integration xml. I'm using spring boot 2.0.2 BOM.

Answer 1

I think the problem that after the first request with the expected-response-type="[B" you get a contetType header as a application/octet-stream and this doesn't fit for the second request where you have a MultiValueMap, but don't have any hooks how to represent it.

I suggest you to add a header-enricher before sending the second request:

<int:service-activator
        input-channel="sourceDocumentOutLv1"
        ref="docConversionOrchestratorImpl" method="processRest1AndSendToRest2"
        output-channel="enrichContentTypeHeaderChannel" />

<int:header-enricher input-channel="enrichContentTypeHeaderChannel" output-channel="sourceDocumentOutLv2">
    <int:header name="contentType" value="multipart/form-data" overwrite="true"/>
</int:header-enricher>