I am using the Google-GCM service for pushing notifications to a mobile device & building this application in Java EE.
I'm perfectly able to push notifications to the mobile device. And from the client-end (mobile) I'm able to receive input(string).
Henceforth my conceptual question starts: When I'm receiving input from a mobile (let's say: "Hello, Server"), I'm trying to build an automated process on the server-side and in reply it will push a notification (let's say: "Hi client, I'm fine; How are you?") automatically.
I want to grab some idea to push the notification automatically whenever the mobile device is registered. How do I do it?
All realistic implementations of GCM include a stage where an app receives a RegID, and communicates the RegID back to the server, typically via an HTTP service, typically along with some other business specific data. The server would store the RegID, associating it with other data, and later use it to send messages.
Have you implemented automated the delivery of the GCM registration ID to the server yet? If so, in the same piece of code, you might as well push a notification back. If not, do put together some. Server-side implementation would depend on your server's platform, naturally.
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I have a Java web application which needs to send manual and automatic notifications to the user.
This notification should go to the user's browser as well as the mobile devices (both iOS & Android).
I found out there is no way to send notifications to mobile devices directly if there is no native application running on the mobile device. So my only option seems to be web push notifications. I went through a few articles and I found it very confusing. I don't know where to start.
Can I send the notifications directly from Java Code? Or do I have to use FCM(Firebse)? If so can I call FCM directly from Java code, such as by calling it using Apache http client libraries?
How does the FCM, client's browser and my application connect?
I also found out that a service worker should run in the background to receive the notifications. How do I integrate it with the Java code?
You can send them directly without using FCM and there are several libraries available, including a Java one.
Unfortunately iOS currently has no support for Web Push. Subscriptions to your service are on a device level rather than by user, so if I sign up on my desktop you cannot send notifications to my mobile unless I sign up again in my mobile browser.
Notifications pushed to Android will be displayed if an instance of the browser is running, in the real world (for me anyway) Chrome always seems to be running in the background somewhere so I get notifications through in pretty much real time. The downside is web push notifications go straight into the notification shade, they do not pop up on screen first.
The rough workflow goes like this:
User visits your page, you load service worker and check for web push
capability, if satisfied you can request permission to send
notifications.
If user grants permission you pass your public key to your service
worker to create a subscription for that user, this returns an
endpoint and two keys which you need to push a notification to them.
Your webpush library runs as a server instance and takes care of all
the encryption and token handling, you configure it however you like
to dispatch messages, usually in response to HTTP POST requests but
it's up to you.
Within your service worker you define an event handler for receipt of
a push message. This is where you create and display the notification
to the user, again how you do this is up to you.
You can pass parameters in the payload of the notification and use them as variables within the notification you display or you can hard code values, you can specify different behaviours depending upon whether the user has your page in focus or not, you can add buttons and set different actions for them, trigger events upon dismissal, customise the vibrate pattern, replace or stack the notifications, access the data in existing notifications etc etc. All this is handled by your service worker, receiving the notification alone does nothing at all.
Your service worker is just a script written in javascript which you link from your page. It is loaded and installed by the browser the first time a user visits and then runs independently when invoked.
Service workers are very powerful. You can also use them to implement complex caching rules, serve content while offline, push data between different browser windows etc. A service worker can spawn more service workers and as they run outside of the main thread of your browser they are ideal for offloading cpu intensive tasks to without delaying the rendering of your page.
Final point to note, your site must be served over SSL to be able to deploy a service worker.
1) It depends a bit on where the Java code that sends a message runs.
If it runs in an Android device, then there is no way to securely send messages from that code. See my answer here for more details: How to send one to one message using Firebase Messaging
If the code runs in an environment you control (such as a server you control, or Cloud Functions), you can call the FCM HTTP end points documented here. The Java Admin SDK doesn't support sending messages yet, although it seems to be under consideration.
Is it possible to create a client written in Java only, which registers just like an android phone client to receive push notifications?
My goal is: I want to create an integration test on my server which tests if a GCM push notification is really being send. I can not mock the sender of the push notification as that is in another part of the system, developed by other people. Mockito will not help me out here alas.
Rob.
You can't use Android APIs in standard Jave as a lot of required libraries are missing.
Although you could write a AndroidTestCase which registers at the server and waits for a notification to arrive. You just need to wait for x seconds. If the notification did not arrive in the timeout or the registration failes, the test case failed.
I'm interested in how apps like WhatsApp implement this feature.
I've just read that it's bad practice to send the message directly from device to device, because someone can eventually get to the API key and send messages as my application.
What's the solution then? Having a server and making the devices only communicate with this server, so when I want to send a message to another device, it goes to the server and from server to that target device?
Also another question:
public void onMessageReceived(String from, Bundle data)
This is a method of the GcmListenerService. When is "from" different than the default senderID? Because I tried sending the message directly from one device to another and the "from" was still the default senderID that I got when I registered the app on the website.
Basically, you need a server to listen to upstream messages and broadcast then again to intended recipients.
You can find an article describing this here: http://javapapers.com/android/android-chat-with-google-gcm-xmpp/
The approach is pretty limited and not as flexible as having your own messaging server, but should be enough for a proof of concept.
I am trying to make an app that connect to the server.
The app is used by some devices.
If one of the devices upload something to the server, I would like other devices receive the notification about the server has something new.
My question is, how to check the server is change or not? How often we must check the server?
I wonder how the Online Messaging work, because someone send something, we receive the message ASAP
Is the concept can be use with my app?
Sounds like you want to take advantage of Google Could Messaging or GCM for short.
http://developer.android.com/guide/google/gcm/index.html
This could be a lightweight message telling the Android application that there is new data to be fetched from the server (for instance, a movie uploaded by a friend), or it could be a message containing up to 4kb of payload data (so apps like instant messaging can consume the message directly).
GCM is the standard for how your apps "talk" to your servers. Either for a message in it's entirety or just a message to go check the server because it's been updated.
Is it possible to open my mobile Java program with an SMS?
And I don't want this SMS to be stored in the inbox. I'm looking for the kind of "Control SMS" that banks use for their mobile applications. I want the same in my application: send SMS to the mobile, the mobile device shows a message on screen that will be opened by the program, and this SMS should not be saved in the inbox.
Are you sure that you're not mistaking push notifications/cloud to device messages for SMS's?
Push/C2D messages are similar to SMS's inasmuch as a central server sends a message out to devices and many apps then display a popup based on that message, but the implementation is completely different. If you're not mistaking the two, is there a reason you'd prefer to use SMS's that are handled differently than most instead of push/C2D messages?
Here's the documentation for Apple's Push Notification Service.
Here's Android's Cloud to Device Messaging documentation which serves the same purpose.
Have a look and see if that would serve your needs.
If you are looking for completely client side J2ME based solution for feature phones - then try push registry. It is available above MIDP2. I don't know the exact details but there you can define event and triggers which will be stored by phone OS and invoked automatically when particular type of event occurs.
SMS sending is separate issue but there are tools available for that definitely.