I have a requirement that my app, can receive events (e.g. messages) from server any time (even if app is not running). So do I need to create an infinitely running service to listen for these events?
This to me seems similar to Email apps in Smartphones, like whenever you receive a new email(event in my case), its able to show notifications and also able to update my list adapter whenever I receive an event.
But I dun know how will I implement this?
You should take a look at C2DM (push-messages):
http://code.google.com/intl/sv-SE/android/c2dm/index.html#intro
it allows a server to send messages to devices at any time.
From the link:
Here are the primary characteristics of Android Cloud to Device
Messaging (C2DM):
It allows third-party application servers to send lightweight messages to their Android applications. The messaging service is not
designed for sending a lot of user content via the messages. Rather,
it should be used to tell the application that there is new data on
the server, so that the application can fetch it.
[...]
An application on an Android device doesn’t need to be running to
receive messages. The system will wake up the application via Intent
broadcast when the the message arrives, as long as the application is
set up with the proper broadcast receiver and permissions.
[...]
Events from server are called "push notifications" and are implemented via "Cloud 2 device messaging" (C2DM). On the mobile side these messages are submitted as broadcast events (see BroadcastReceiver). For a complete example see some tutorials: Google, Vogella or here on Stackoverflow
I think you have to start a Service as soon as the device booted. There is a good tutorial here how to achieve this.
Related
I am developing a VoIP application with SIP as the signaling protocol. I have implemented the messaging and calling functions and they work when the app is in the foreground. To make the app listen to the call and message receiving when it is closed, I created a foreground notification so that the app would always be in the foreground.
The problem is that the above method consumes a lot of power which is unacceptable. I have also noted that famous VoIP applications like WhatsApp and Signal are not using foreground notifications but, they manage to inform us about incoming calls/messages no matter the app is closed. I wonder how to achieve the same functionality. Could anybody please point me in the right direction?
This kind of App should use Push Notifications (reference: https://firebase.google.com/docs/cloud-messaging) that use ONE SINGLE socket connection for the whole system: each App should register itself for receiving Push, then when the Server triggers (many languages are supported by FCM with examples/tutorials) the Calling Event then a special "message" is sent to the App (providing some information about IP or whatever you want) that gets those information and acts in the proper way.
Unfortunately FCM, after few thousand notification per month, requires payment.
There are other similar online service, but those services requires a fee because they should handle many users connected at the same time and it requires hardwar and bandwidth.
I come from the JavaEE development and I'm totally new to android app developement and I'm a bit confused how to implement my requirements. I have a server, where the user has to authetificate and can perform CRUD-Operations via REST-webservice. When a specific event is triggered server-side I want to send a notification to the app. The user should recive the notification even when the app is not running at the moment.
So now my questions:
What do I need on client side so I can recieve this notifications even when the app is not running? Or do I recieve them even if the app is not running? The data input from the notification needs to be safed app-side.
How do I send a notification from my server if the event is triggered? Do I have to use FCM(/GCM?) or can I directly send notifications from my server to the app?
Any help is appreciated!
Typically, 'instant notifications' are done via websocket severs, for mitigating the process of setting one up yourself, people typically use something like Pusher, which has a library available for java, or you can obviously use FCM/GCM. In conjunction with this document you should be able to keep the service running on the andriod app even when running in the backround so you can still send notifications, just remember you'll have to still attempt to detect if they have internet connection or not when sending out those notifications.
I know that we can't set repeating alarms of short intervals in Android because it drains battery and has other such effects. Well, technically you can, but android will automatically push it up to a minute citing "suspiciously short duration".
So how exactly does an app like WhatsApp or Facebook constantly update our messages or newsfeed? I thought they fire an Alarm each second, but clearly that is impossible because the OS will push it up to a minute anyway. Using Handlers/Threads is off the question anyway because they don't fire when the app is closed, but WhatsApp updates your messages even when the app is closed.
So what exactly do these apps use if not AlarmManager to do the aforementioned task, and if they use AlarmManager, how do they set the short duration?
They have a service that uses push messaging. So basically they open a socket connection to a server and sleep until the server sends data to them. Its an interrupt mechanism, not a poll.
Not specific to any service like WhatsApp or Facebook, the idea behind this whole system works like this.
For Android in particular (or in general),
Your device registers with the Google Cloud Messaging (GCM) service
It allows GCM to create a HTTP persistent connection with your device
This connection is lightweight and persistent (stay alive for a long time)
With this, you will be able to consume these services, sending messages in this fashion.
Your Server ---> Google GCM Service ---> Target Device
When you send your messages, do not include the whole message itself. You should keep it lightweight by just sending simple messages to notify the targeted device that it has new information to be downloaded.
At your device application, you set up permissions and intent to listen for these push notifications. Whenever, there is new messages, you will make a request to your server to receive the corresponding messages.
Here's a guide to explain in depth: https://github.com/codepath/android_guides/wiki/Google-Cloud-Messaging
Cheers! Happy Programming!
I'm trying to build a GCM notification listener, which will basically use the notification to flag the user that some operation should be made (which involve communicating with my remote App-Server).
I assumed that I should create a UI-less application running on the device's startup and listen to the GCM notifications and issue the internal android notification. When the user opens the notification an activity will be opened which will do the rest of the job with the remote App-Server.
Looking at notification examples it seems to me that I may be missing some basic understanding since all te examples which I had found use a UI application to manipulate the notifications.
What do I miss?
The common use case for handling of GCM messages in Android apps is as follows :
Your app registers to GCM upon startup and sends the registration ID to your server.
Your server sends a GCM message to your app.
You app receives the message in a broadcast receiver, which usually starts an intent service.
The intent service usually displays a notification to the user.
The user taps the notification, which starts an activity of the app.
You can see this use case implemented in the official GCM demo and in many other examples.
The fact that the app you wish to develop has no UI doesn't prevent you from implementing the exact same use case.
One user manages mobile users via a website interface. By clicking on a button on that website I have to display the current position of the chosen mobile user. So what I need to do is send something to the mobile app to trigger sending the GPS position to my server. My website then starts polling the database to check every 10sec whether the GPS coordinates have arrived.
Questions:
Is it possible to use Push Notifications for this purpose? I already implemented it, so everything would be there.
Can I do that silently, so that the mobile user doesn't get notified? I have found something called Silent Push Notifications - is that what I'm searching for?
I have to do it on Android and iOS.
On Android it is definitelly possible. There is no default behavior (such as alerts/badges/sounds) to notify the user of the app that they got a notification. When the app gets a push notification, a broadcast receiver is created and its onReceive method executed. You can have whatever logic you need in that method, though if you require a logic that requires a long time to execute (such as server calls), you should start an intent service from the receiver and do you logic in the service (get the location of the device and send it to your server).
On iOS I believe it is possible since iOS7. Until iOS7, the application logic for handling the push notification would only be triggered after the user clicks on the notification/alert to open the app. iOS7 enable the app to do background processing as a result of the arriving push notification. I believe you should use the {"aps":{"content-available"=1}} payload in this case (which is used for background content downloads), since you don't want any payload that would be displayed to the user.
For android you have some ways to implement the push service:
GCM - http://developer.android.com/google/gcm/index.html:
MQTT - http://mqtt.org/
implement your own persistent connection.
All of them have their advantages. If you need a ack that the mobile client got the msg you should use MQTT. It is also faster than GCM because of less overhead and you don't have the GCM server in between. On the other hand GCM is easy to implement and you don't have to worry about the persistent TCP connection from your server.
Also the silent way is possible because you just trigger a service each time. so if you don't want a notification, the user don't get it.
I am not sure about iOS. For iOS6 it was not possible to implement your own service, which is necessary to "wake up" your app. I am not sure about about iOS7. So for iOS6 you definitely need to use Apples push server.