How do notifications work?



  • I’m trying to understand how should I use notifications. What I’ve been seeing around is that you can use notifications to signal events from one module to another. For example I could use a button to send a notification to show or hide some module.

    What I have not found is how do I use this notifications? Do I write them in the config.js file?

    To give a little bit of context, what I am trying to do is to build a small magic mirror that will show one module at a time and will change modules whenever I push a button (or any other notification). I want to achieve this using the MMM-ProfileSwitcher by tosti007. About the notifications, I will probably use MMM-Button.



  • Basically, the real-world notification usages are not centralized by MM. MM provides only protocol.
    So, if you want to use other module’s notifications, first you should know which notifications could be available in the module.
    Some modules are never using notifications. Some module only broadcasts. Some only listens. A few can send and receive. There is no rule,
    By example, If you want to order other module to sleep, there is no notification to do that. Why there is no MSG_SLEEP_YOURSELF? I don’t know. I believe it shoude have been, but not.

    Therefore, when you want to control some module’s fuction externally, first you should read the manual or source codes to find which notifications are available, oterwise you can request the module developer to add specific notifications.



  • In real-world, hide and show other module mechanism is not lying on the notification system.
    All the modules which are able to hide and sleep others use MM.hide()and .show() methods. There is no implement about delegation for those action to target module. So, controlling other module with notification is just ideal thing until real implements are provided.



  • Finally, let’s see how to make showing module one by one by pressing button.
    The easist way is to make your module by your self, not a joke.
    MMM-Button only broadcasts BTN_PRESSED message. And MMM-ProfileSwitcher doesn’t understand that message. Therefore if you want to use these two modules, you should modify both of them to send and receive proper Message and payload to carry profile informations. That modification is ideally equal to make it from scratch by yourself.


  • Module Developer

    @Sruc91 I’m doing something similar. Take a look at the MMM-Buttons module to see how to capture the button press and send notifications, and then take a look at MMM-Profile switcher to see how it receives notifications.

    In my case, I modified MMM-ProfileSwitcher to receive a “CYCLE_PROFILE” notification that cycles through a list of configured profiles. PM me and I can send you my modified version.



  • @Sean That does make sense, thank you. In some modules’ descriptions they are just mentioned but no indication on how one should use them.

    @j-e-f-f So I see that in the MMM-Buttons module the notifications are defined in the config file and you can use the needed payload to send information.

    So if I understand correctly, if I send a notification from MMM-Buttons like so:

    this.sendNotification('CURRENT_PROFILE', 'DESIRED_PROFILE_NAME_HERE');
    

    Do I just send the desired notification with the payload of the desired profile and the ProfileSwitcher will understand it?



  • @Sruc91 as i know, you are right.
    Or you can build your ‘translator’ module which send CURRENT_PROFILE message when BTN_PRESSED message is coming between btn module and prflswtchr module… Its better to keep original legacy codes.


  • Module Developer

    @Sruc91 well yeah, but the way MMM-Buttons works, it would send the same payload each time. So if you configured the button press to send the notification ‘CURRENT_PROFILE’ with the payload ‘Jeff’, each button press would be a request to show Jeff’s profile.

    So you need something that always receives the same notification/payload pair to do something different each time with it. That’s what my modification to ‘MMM-ProfileSwitcher’ does, or you can do as @Sean says and write another module to keep track of which profile is next and relay the ‘CURRENT_PROFILE’ notification to the MMM-ProfileSwitcher.



  • @j-e-f-f That makes sense, thank you very much.

    Is there any way that I can track those notifications? Like for example, if I send a notification with the MMM-Buttons, is it registered anyway that I can check?


  • Module Developer

    @Sruc91 you’ll see output in Electron’s console when the event is broadcast.


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