After some hours of digging, I found out that NGINX was the reason for the entire problem: It was not configured to pass the POST data to the proxied API server.

Thus, there is no problem with the original API code - I guess that the scenario, as stated in my second update, may be related to the entity's content being empty, once it is read (Somewhere, I read about it being a stream, rather than a storage variable, but I'm not 100% sure about that)

Anyway, I apologize for causing this false alarm and thank you for your support.

Keep up the good work on this tool

Best regards,
fbu

Based on my previous update, I tested a workaround solution, by simply instantiating the JSONObject, based on the text value returned by the entity:

JSONObject data = new JSONObject(entity.getText());

This works perfectly fine for me, when bypassing the NGINX.

I still don't know what the actual problem is, but it works like this for me - I only need to fix the problem related to NGINX.

Thanks for your help, Victor. Hopefully the root cause of this problem can be determined.

Kind regards,
fbu

Previously, I was using an NGINX in front of Tomcat9 for hostname and SSL/TLS handling.

When bypassing that NGINX and going directly to the Tomcat, the entity.getText() actually returns the provided data as string. However, new JsonRepresentation(endity).getJsonObject() and .getText() still return NULL and cause the same NullPointerException, as before. (see attachment for debug messages)

I am pretty much out of ideas, right now. I'll still try to at least get a similar result with using NGINX, as I will need it in the future, but this might just be a configuration error.

Hope this helps.

Kind regards,
fbu

I managed to build the changed source code for the API and deploy it on tomcat. You can find the changes in the attachment "sourcecode_change.png" (lines 103 - 108).

The debug-messages are printed in the screenshot "debug_messages.png". I shows that entity.getText() returns NULL, which causes the StringReader called by getJsonObject() (now in line 107) to throw a NullPointerException (as seen in "nullpointer_cause.png".

However, I still don't know why getText() returns NULL in the first place ... I will keep searching for the cause, but I'm not feeling to optimistic about my chances.

Hope, I could help, so far.

Best regards,
fbu

Kind regards,
fbu

Best regards,
Victor

I added a screenshot of the stack trace for the NullPointerException. (Note that the date does not match, because I simply placed the request, again. But it is the same, as for the previous requests)

There are different debug outputs as well, but they are all related to other requests, this error message and stack trace are the first log lines that appear, when performing the request.

Best regards,
fbu

I just tested on my build system and it seems to work. This is Jetty log:

2019-10-18 18:03:01,532 DEBUG | qtp635934462-14 | org.netxms.websvc.handlers.AbstractHandler              | POST: data = {"columns":[{"isRegexp":false,"dciName":"System.CPU.Usage","columnName":"System.CPU.Usage"}],"baseObject":"2"}
2019-10-18 18:03:01,533 DEBUG | qtp635934462-14 | org.netxms.websvc.handlers.AbstractHandler              | session_handle: f5b2061a-92f2-439e-b971-8769e7d85fd0
2019-10-18 18:03:01,533 DEBUG | qtp635934462-14 | org.netxms.websvc.handlers.AbstractHandler              | Handler attached to session f5b2061a-92f2-439e-b971-8769e7d85fd0
2019-10-18 18:03:01,533 DEBUG | qtp635934462-14 | org.netxms.websvc.handlers.AbstractHandler              | POST adhoc summaryTable: baseObject = 2
Oct 18, 2019 6:03:01 PM org.restlet.engine.log.LogFilter afterHandle
INFO: 2019-10-18	18:03:01	127.0.0.1	admin	127.0.0.1	8000	POST	/summaryTable/adHoc	-	200	115	130	12	http://127.0.0.1:8000	Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:69.0) Gecko/20100101 Firefox/69.0	-

and request screenshot attached.

Best regards,
Victor

do you have stack trace below "caused by"? Because this is seems to be root cause.

Best regards,
Victor