Spring cloud data flow Httpclient - spring-integration

Question

I have the following stream.
Context of the problem
1.
rabbit --password='******' --queues=springdataflow-q --virtual-host=springdataflow --host=172.24.172.184 --username=springdataflow | transform | httpclient --url-expression='http://172.20.24.47:8080/push' --http-method=POST --headers-expression={'Content-Type':'application/x-www-form-urlencoded'} --body-expression={arg1:payload} | log
2.
I have spring boot running locally.
#RestController
public class HelloController {
#RequestMapping(value = "/push", method = RequestMethod.POST,produces = {MediaType.TEXT_PLAIN})
public String pushMessage(#RequestParam(value="arg1") String payload) {
System.out.println(payload);
return payload;
}
}
I would like to have the rabbit message come into httpclient as value for the the 'arg1' parameter value to the post request. The intent being that message published on rabbit queue is consumed by a rest post point, the message being captured by SpEL payload.
For this I am using the body-expression = {arg1:payload} but this is not working, maybe syntactically wrong.
Any suggestions ?

Answer 1

The #RequestParam(value="arg1") is really about request param, the part of the URL after ?, which is called query string: https://en.wikipedia.org/wiki/Query_string.
So, if you really would like to have an arg1=payload pair in the query string, you need to use a proper url-expression:
--url-expression='http://172.20.24.47:8080/push?arg1='+payload

Answer 2

This seems to work to pass strings as payloads. It seems that by default the payload becomes requestbody.
So on the rest service I made a change:
#RequestMapping(value = "/pushbody", method = RequestMethod.POST,consumes = {MediaType.TEXT_PLAIN})
public String pushBody(#RequestBody String payload) {
System.out.println(payload);
return payload;
}
And the stream that seems to work now is :
rabbit --password='******' --queues=springdataflow-q1 --host=172.24.172.184 --virtual-host=springdataflow --username=springdataflow | httpclient --http-method=POST --headers-expression={'Content-Type':'text/plain'} --url=http://172.20.24.47:8080/pushbody | log
I did try with inputType= text/plain suggestion both on httpclient and logsink and removing the consumes and produces on the rest service post method, but no luck there.