LabPlot's MQTT in the finish line

Hello everyone. GSoC is coming to its end, so I think that I should give a report about what's been done since the last post, and also make a brief evaluation, summary of the project itself. 

As I've written in my last post, the main focus was on improving the quality of the code, cleaning, optimizing and properly documenting it. And also making it more comestible for other developers. 

The next step was searching for bugs and then fixing them. In order to do this properly, I implemented a unit test for the main MQTT related features. This proved to be useful since it helped discover several hidden bugs and errors which were all corrected. The main features, that tests were developed for, are: checking if a topic contains another one, checking if two topics are "common topics" (meaning they only differ at only one level, and are the same size), managing messages, subscribing&unsubscribing.

As I said in the previous post, a problem was that LabPlot couldn't plot QDateTime, so using an index column was necessary. However, fortunately Alexander Semke, as he promised, dealt with the matter, so plotting of data from a single topic is now possible without needing any plus/additional data. I'm truly thankful to Alexander for this.

The main improvements were related to algorithms needed for subscribing and unsubscribing. This process is now more optimal, and I really hope that is bug-free, since a lot of time was spent on testing every possible scenario for this feature. Not only the algorithms were improved regarding this feature, but the user interface as well. Now we use two tree widgets, which really does look better than the previous list widget (used for listing subscriptions). Using the tree widget for listing subscriptions made room for further improvements. Now not only the subscription is listed, but if the subscription contains wildcards, then every topic contained by the subscription and present in the topic tree will be added as children of the subscription, in order to make the user's life easier. Searching for root subscriptions in the tree widget is possible just like in the case of the topic tree widget.

 

New UI for subscribing&unsubscribing

Another improvement is dealing properly with multiple MQTTClient objects, which wasn't quite alright at the time of the last post. Now it works fine, and the user can easily control each of the MQTTClients using the LiveDataDock. Another bug/absurdity was fixed. Namely, the user could add more MQTTClients with the same hostname, which is quite illogical (since the user can control every topic of a broker with a single MQTTClient). Another minor visual improvement is that an icon for MQTTClient and MQTTSubscripiton was added.

 

Dealing with multiple MQTTClients

As I presented the major improvements, I think it's high time I showed you a possible and practical use of the features developed and the benefits of LabPlot having MQTT support. MQTT, as I mentioned in earlier posts, is mainly used to communicate data collected by sensors. So if one had the possibility and adequate sensors, then one can save&plot data collected by those sensors. However, there are less sophisticated uses as well. As we all know our phones have quite a few sensors, which could be put to use. And there is an application for this, which can be used by everyone who owns a smartphone: Sensor Node Free. In the app the user can choose from multiple sensors, the data of which can be sent to a preferred MQTT broker using a preferred topic name. As you can see in the next picture.

Choosing the sensors, setting the broker and the topic name in the app

Of course, any app, that has these features, could be used (for example a fitness app), but my mentor suggested this one.  The data of these sensors will be ploted in the demo video. Almost every sensor sends data divided to x, y, z axis. These 3 will be shown in the same plot, their data set as Y value, and the QDateTime allocated to the values as X value. the curves based on data from x axis will be red, the y axis green, and the z axis purple. The plotting was done for a while before starting to record the video. So here is the demo video:

Demo video

And finally here comes the evaluation/summary. I truly think that every feature presented in my proposal is implemented and working. So I think the main aim is met: LabPlot now has full support for MQTT. There were difficulties along the way, but with work, and help from my mentor, everything was dealt with. As I said everything works, but some unforeseen bugs or errors might appear in the future. Some steps for the future may be to improve the overall performance of the new features.

Working on this project for the last 3 months has been a very great experience, and I can honestly say that I improved my coding skills and way of thinking in a way I haven't even dreamt for. I'm more than grateful to my mentor, Kristóf, who always helped me and had my back if I encountered any hardship. I'd also like to express my gratitude towards Alexander Semke, my mentor's former mentor and an invaluable member of the LabPlot team, who also helped me a great deal. I am determined to further improve the features, even after GSoC ended. I would be more than happy to stay in this amazing team and help them whenever they need me. It's my goal for next summer to join GSoC  again and work on LabPlot with Kristof, since I really liked being part of this team. I truly think that people should contribute more to the open source community, and the end of GSoC shouldn't mean the end of the involvement as well.

This is it, guys. Thank you for reading the post, and thank you for your interest in my project. If there's any development regarding my project or a new task (in the future) I'll let you know here. Bye :)