No connection between Freeboard's data source

Question

I've been trying to connect Freeboard to visualize context information from OCB, however came across difficulties that prevent me from receiving any data from there. My thinking is that there is a problem with connecting Freeboard to OCB, because in OCB's subscription list there are no any new entries, and datasource in Freeboard shows that it has never been updated.

OCB is turned on as a docker container. Freeboards run in docker host.

I tried setting the ip as ip that I extracted from docker by:

    sudo docker inspect --format '{{ .NetworkSettings.IPAddress }}' orion1

It gave me 172.17.0.3, but on that it didn't work either. I guess it shouldn't have anyways, because I can communicate with OCB by localhost:1026 as long as I do it via cUrl or Insomnia. I can push new entities, update and so on.

The accumulation server that has not been working (link here) is ok right now. But the thing is, I add subscription by myself and can't run the acc server on localhost (loopback interface), but rather on other avaliable interface, then add ip of that interface to subscription payload that i send to OCB. Maybe there is a conflict with Freeboard somewhere.

Answer 1

The issue here was connected to lack of CORS support. The easy solution for this is just enabling CORS functionality while launching Orion Context Broker as described here.

I have conducted quite an (actually unnecessary) research on this topic and came up with over-the-top solution for the problem which is described in this github post. There is a proxy server approach for solving the issue. I wanted to propose adding CORS support to Orion Context Broker, and was kindly surprised when found out about it being already implemented.

There are posts like this, this and this which was very helpful in solving the case.

However, I have a two requests. I guess @fgalan is a go to person right now, regarding back-end and documentation of OCB and peripheral software.

1. Can there be a stronger emphasis put on CORS and ACCESS-CONTROL-ALLOW-ORIGIN soulution? The reasoning behind it is that it gives a seamless connection between OCB and any front-endy application or site (i.e. Freeboard) running in internet Browser. It shouldn't be so hidden that I came across the solution for my problems just by accident while looking for something else. I guess putting it in some walkthrough documentation on I don't know some other visible place. The problem is that I spent two weeks trying to solve it and after all went for the over-the-top and unnecessary solution while the easy and accessible was just under my nose. Good thing is that I have a good connection on stack and git so it was resolved. There are probably people that gave up on Freeboard after any slip with it. And it's a shame, because for now there is no better opensource piece of software for visualization than Freeboard. And the problem is not only with Freeboard, as I said it concerns many more front-end applications and solutions. As we go with FIWARE's way of thinking, those things should be resolved differently.

2. The FIWARE datasource plugin for Freeboard is not worth a dime at the moment. As @fgalan pointed out in comment it was developed for v1 version of Orion Context Broker API and has not been updated. Therefore it's way more complicated than it's suppose to be. As documentation of OCB fairly point out, v1 approach is not really RESTfull like. After conducting a short code review of OCB plugin for Freeboard I can say that's not worth using. As far as I understand it should still be working, because OCB allows for v1 request to be conducted (but it doesn't work for me anyway), those request are deprecated. In my opinion new post regarding topic should appear (not sure who should I contact about it), because this is a bit misleading. What's the point of using piece of software that's deprecated and spreading bad habits regarding interacting with OCB?

   Solution for this is in my opinion simple. Just use JSON datasource in Freeboard. I understand motivation behind creating individual datasource plugin for Freeboard in 2015, when there was not RESTfull v2 version of OCB API, but there is one now, so why not use it? I used ever since got rid of difficulties with CORS and it works pretty well in my opinion. Freeboard as I said earlier provides great opportunities while being easy in setup and maintenance. It should not be abandoned so easily.

   By using GET request for JSON payload in Freeboard, now we have whole access to query for context from OCB. It doesn't need any POST methods as long as we use Freeboard as it supposed to be used (by querying for data to visualize). Throw in

             ?options=keyValues
   

   to the request's URL and we've gotten ourselves a really smart and compact way of visualizing data coming from the Broker.

   That's just the way I thing it should be resolved. Last update on this topic coming in 2015 is just not enough in my opinion, especially if there were better methods developed on accessing context data from OCB.