Develop Reference

Push Notification from local server

I am building my first Android app and need to know how I could use push notification.
My project is a home alarm system and also I have built my own local web server. Now I want to push a notification from my server to my Android app when an alarm appears in my server.
Currently my garage doors use the MyQ app and when the garage door opens or closes I get a notification on my phone, I want to implement the same thing in my app.
I've been reading about the Google Firebase Cloud Messaging but it seems exceeding my need.

If you need push notification on your cell phone then you definitely need to integrate your app with Google Firebase. (or at least that's the right way of doing it).
Alternatively, there is something called as local notifications & background process in Android you could do long polling to check if the garage door is open (probably every 2 mins or something). However, I don't recommend that as it can drain your mobile battery.
Also I recommend using Flutter as oppose to using Native Android. As there are some pre-built libraries for android and Google Firebase integration.
Take a look at this Youtube video - https://www.youtube.com/watch?v=2TSm2YGBT1s

Ouh, maybe thats a little bit too much for starting with android - nevertheless I want to help you.
You need a communication protocol between your server and your phone (i.e. Firebase as you mentioned or Websockets).
If your server sends a message to you client (your phone) you have to create a notification. (Android Developer Guide). That's the theoretical part. You will also stumble across a lot of
challenges with
asynchronous programming.

Firebase might actually be the simplest option. You could build your own web socket service too, but that would probably be more than you need. See this previous question for more options: Android push notification without firebase

Android has some services that communicate with firebase to receive notifications.
You'll need to implement a service on top of your web server (using backend languages such as Python, Node.js, PHP,...) so it can send notifications when an event happened (like the door closed) witch isn't a simple way for a beginner.
then your web server sends a message to firebase and tells it to send a notification to my client.
so I highly recommend using firebase because of the simplicity of usage. otherwise, you should implement a separate service on your android phone to get the notification (if you want to run it locally) also as explained do the backend side.

create my own push notification service without fcm , pusher ,

I want to create a notification system provider that is not based on Google services or similar. In fact, I want to get information about its overall architecture and needed Android sdk functionality.
The most weird point for me is to understand how to send a notification to an Android device.
I mean, how can I identify the Android device on which my application is installed from millions and millions of other Android devices on the Internet?
And how do I send information to him?
Should I use sockets for this or similar stuff?

simple answer: YOU CAN NOT
before everything else i should correct your question, pusher and FCM are not in the same group at all! you can build somthing like pusher or oneSignal or etc but you can not build something like FCM/APNS
you should understand three simple yet important sentences below:
when you want to pull anything from place_1(e.g. api) to place_2(e.g. browser_client) you most have an identifier of the place_1_resource (which commonly is the uniform-resource-locator of api)
when you want to push anything from place_1(e.g. notification_central_server) to place_2(cellphone_client) you most have an identifier of the place_2_resource
you must know the differences between a real server push with server-push-like technologies like long-pulling or ... and you should be aware that what is intended in this concept is a real server push not any kind of pulling with a push jacket!
if you don't have any identifier for a cellphone which you want to send it a notification, your server dont know where to send that notification so we need a resource_identifier_like for cellphones which is actually a device_token_like and you have just one approach to get this device_token_like and that is the FCM/APNS
FCM is like a dns server containing all identifiers of every android device that google supports (almost every android device) and APNS is just the same but for apple devices
note1: even if your app can obtain it's corresponding device device_token_like it can not be used for push notification if its not registered on FCM/APNS
so when you get that device_token_like identifier of your desired clinet_device now you can use different approaches for sending sth to that clinet_device. there are several approaches like SSE, Webpush, HTTP_server_push, Pushlet and etc but none of these approaches supported by mother_companies of these devices, the only approach that is completely supported and standard is the same approach that FCM/APNS official websites suggests
for example an iranian Incorporation named najva uses webpush to send notifications because of USA sanctions but webPush method works good on browsers and android devices but they didn't even apear on an apple devices
finally i should say that i admire your curiosity to less using anything from a benefit_based Inc. like FCM/APNS in your developing but i strongly recommend these articles and books for you cause i think you didn't learn enough:
wikipedia of push technology
story of some guy who tries to make his own push notification service
Push Technology A Complete Guide - 2020 Edition
Data Push Apps with HTML5 SSE

Short, direct answer
You can't (At least till you create your own ROM)
TL;DR, Reason why?
Before you build your own push notification server, you first need to know how it works internally in android.
Whenever you/your server sends a push notification message to the android client, the SDK processes it and shows you the notification. But when your app is not running (or being killed), your app cannot respond to it since it was not running. In such a case, your notification message is sent to a system service which is known as Google play service. For this even to work, you will first need to bind your app with Google play service and that is what FCM does. FCM SDK registers your app to the operating system service on the first initialization. That FCM service is opened to a port which listened to the incoming message from the server and when it receives the message, it publishes a notification on behalf of your app with a PendingIntent containing the data. Then the PendingIntent is delivered to your app when the user clicks it and then finally your app process the data (or the push message)
So basically, for your server to communicate with the client, It first needs to communicate with the FCM service and for that, FCM gives you a token which identifies the application to register with the internal Google play service.
Simplified furthermore, the workflow is as follows:-
Server send push message ---> FCM ---> Google play service,
If your app is running, it is directly handled by the client SDK So, Google play service --> Your app
If not, then it is delivered by the service itself using PendingIntent So, Google play service --> PendingIntent --->| Publish notification
Totally impossible, Workaround?
There is nothing like impossible because an absolute impossibility doesn't exist. Saying impossible generally means near to impossible. (This is similar to math where also we say tends to infinity because no one has achieved it yet).
To make it work, you need to somehow bind your app to the Google play service and you can't because Google hasn't exposed any direct API to do that. The only possible way is using the FCM ;-) (Bad luck again). So the only possible way is to build your own custom ROM with a custom push service that acts as a client for your Push server and a Server for your Push client (which is your app).
Since the above option tends to impossibility, you have to choose a workaround.
The best among the worst workarounds are:-
To make a malicious SDK.
Malicious because it needs to keep the app running in the background with a service that is connected to a WebSocket endpoint of your server. (Harder in new android versions).
Make use of a database where your push notification is saved and your app checks it periodically using AlarmManager.
Hope you have got the point.

NodeJS to android app communication

I'm making a NodeJS server and an Android app that goes with it. I need to send alerts to my mobile app users that's coming from the web server. Something like a a chat app on the server and the android users getting the messages also (Facebook messenger?).
I have the server ready and Android app communicating to its database (for user login/getting user info/etc) using REST. I just need to figure out how to send info to the Android app WITH THE SERVER INITIATING COMMUNICATION. Any advice on where to start?

Start by looking at Google Cloud Messaging.
It's a free service that accepts messages from your server-based program and queues it to be sent to phones with your app when the phones are online.
Here is the overview on Android Developers.

YES!
Working with NodeJS, you have probably already heard of Socket.IO.
I'd say: Start there!
For your app to communicate with the server, there's also the java lib. These are great tools to start making any good real time service.
After you get along with this, you should also check GCM as #krisLarson suggested. And talkign about GCM, you have Node-GCM to make your work even easier.
Good luck!

send and receive notifications in android

I am developing an app in android in Eclipse IDE. The app modality requires that any user can challenge his/her friend to do a certain activity. Whenever a user does so, the friend will immediately get a notification in his/her phone. Even more, the user who challenged the friend, will also receive a notification when the friend accepts the challenge. Is there any particular way I can provide this functionality? I know how to generate notifications. But the server side interaction is quite confusing. Should I check the server database through the app at frequent intervals and check for such activities in database? I think the procedure will hamper the performance of the app. I would be very grateful if anyone can suggest a good way.

But the server side interaction is quite confusing.
As you're pointing out, it's the server part not the Android one what's confusing here. If you don't have any constraints on the server part, I'd recomend to use Socket.io http://socket.io/ They have a tutorial for connecting socket.io with Android: http://socket.io/blog/native-socket-io-and-android/

It seems that you don't really need an interaction between the differents users but only a way to notify them. I always used Google Cloud Messaging to do so. It enables you to receive push notifications. As you said, checking the server periodically is battery/data consuming and not the best way to do it.
This link might help to set up GCM : http://www.androidhive.info/2012/10/android-push-notifications-using-google-cloud-messaging-gcm-php-and-mysql/.

PushNotifications - How to Implement

I am a newbie in android. I have developed few applications, but all are plain and simple, just used the built in features of android.
I was asked about push notifications, in one of my interviews and I decided to have a look at what Push Notifications are. I understand the concept of Push Notifications(I think), but whenever I read the term "Server", it's freaking me out.
I understand all the client side coding, but I don't get how to implement the server side coding. I have seen some people use XMPP, MQTT, etc., What are those? Here is my scenario and what I want to know..
Scenario ::: Let's say I have a website, with a table (the values are retrieved from database), where I update a few columns every day. I want these updates to be reflected in my android application. So, as I have read, push notifications can tell the application that there are updates available. Good. I am fine till here..
When the application gets the notification, should my application, contact the website and get the latest information? or will the updated information sent through Push Notification? I guess, my application would be contacting the website and get the information. Now, how do I get the data from the website? Should I get the source of the page and do some kind of parsing or something?
I will be asking more questions, as the experts clear my questions...
Sorry, if my questions are too naive, but this is the only place that can help me...

Push Notifications means Google Cloud Messaging for Android (GCM) is a service that allows you to send data from your server to your users' Android-powered device.
You can refer to this documentation
Google Cloud Messaging for Android
GCM: Getting Started
And there is also Demo App Tutorial given

in your case you need to create HTTP web service for getting data from the server.so when you get notification about update on server side.you just need to call this web service and get the data you need to update