From server how to call an Android app without any request? - android

In my app I have functionality like server-side some updates is done. When every updates is happen in server-side I need send those data to app without using push notifications.
Take example of Ola Cabs. Whenever user open the app it will show all cabs information nearby user. At the same time it will send data to the cab drivers telling that a customer needs cab like that. How to implement this functionality with out push notifications?
By using this things we can do that
1) push notifications
2) explicitly calling the server from client with given time (its bad process)
Is there any solution other than these things?

How could client get response without request? Please read OSI Model and TCP/IP protocol. Because server cannot send response without request. So client have to initialize request first and wait for response from server.
If you want to do same thing without GCM then i will suggest you to use socket programming. In that you can be open client port continuously to receive messages (response) without any request initiated by client.
But again, continuously opening socket port, drains device batteries, and this is bad process. In case of GCM it only open port for while when client send request to server and close after response. So I suggest you to use GCM but still you have problem with GCM then use socket programming like chat applications (e.g WhatsApp)

Related

Receive information through the socket does not work properly

I am developing a multiplayer android game, which is sending information through sockets. The game is working fine, but sometimes, it seems that the information that is being sent does not get received. Therefore, I would like a way to ensure that the information goes through. Is this possible?
You have to ensure it yourself,(i'm assuming you are developping the server side as well.) For exemple you can create a server response for each message you send through the socket and try to resend this message as long as the server don't respond correctly.

push notification for my android chat application

iam developing a chat application and now am on it's push notification part.. And now am in a big confusion.. because in my previous application iam using Google's GCM like, whenever i get a notification from the GCM server i pull data from my server.But in this case i think it's not the right way for a chat because if i try to do like this i have to connect the socket again and user will become in online status.And also am using raw socket for my application.
is there a better way for accomplishing this?
thank you
I am using web socket for push notifications. In my android application (client side) I use Autobahn web socket client. It works fine, but if you want reliable solution then I think you can go for Azure Push Notification Service. But I think you can only send/receive few push notifications using their free service. To scale further you need to pay.
But using web socket you can send as many number of notifications as you want. Further, you can keep the connection always on, so that you don't need to reconnect the socket connection every time. But to ensure the active web socket connection you need implement PingPong. And that PingPong might use some the bandwidth.

Android apps and server connections

I am an android user and of course I use whatsapp, twitter for android, facebook and many other apps that notify me of events.
As a proogramer whats keeps me wondering is how fast notifications or whatsapp messages arrive.
My intuition tells me that is not possible for the whatsapp or twitter server to open a TCP connection with my cellphone by a given port to deliver a new message. If i am in wifi mode the router would block that connection.
And if my whatsapp client is pooling the server every second.... Poor server if it has 1000 clients making request every second.
What is the approach to face this issue?.
Is there some other protocol involved?.
Those apps use services that utilize "long polling" - primarily based on XMPP or some variation of XMPP (like jabber - http://www.jabber.org/). The client does not poll often. A quote for the Wiki page:
The original and "native" transport protocol for XMPP is Transmission
Control Protocol (TCP), using open-ended XML streams over long-lived
TCP connections.
It sends a message to the server that basically is a mechanism for the server to send a message back at any time (as long as the client is available). It's like sending a request to an HTTP server and the server "time-out" does not occur for a very long time (hours), so the client just waits. If the server receives a message destined for the client, it sends a "response" to that request. After the time out does occur, the client sends another request and waits.
GCM does the same thing - but does not require you to setup servers for all portions of the connection. It's easy to search for GCM, AWS, etc. to see examples.
Typically GCM should be used if you dont want to guarantee immediate delivery and it is okay for your app to miss out on certain messages.
This is because GCM tries to optimize by bundling several messages (even from other apps) into a single package. And it has a limited buffer to maintain the messages per device (in case the device is not reachable).
Here is just one way to do the job.

What mechanism to use for push-messages?

This is not a question for a ready-to-use solution including sources but for getting ideas/hints/tips for a solution.
Assumed I have a messenger. User A types some text that has to be sent to user B. This text is sent to a central server first where it is stored when user B is not online or where it has to be transmitted to user B immediately when he is available.
For second case, what mechanism should be used here on a mobile device?
1.) Let the messenger of user B open a client connection to the server and to permanently receive data from there does not sound good to me. When the connection is interrupted it has to be re-established - possible until next interruption. So establishing of such a connection may cause traffic and consume power without transporting any payload in between.
2.) Let the messenger use a ServerSocket and let the central "server" connect to the device has the same problems: the connection may be interrupted.
So my question: is there a mechanism available for mobile devices that transmits such messages only in case they are available and establishes a connection only when it is needed? Some kind of automated push-notification without permanent connection between client and server?
It is recomended to use GCM for Android. Here You have nice tutorial. You could also use frameworks like Parse.
Either
1. Have a persistent connection between client and the server. Client can poll at a predifined interval to check incoming payload. You may have to optimize the 'poll' logic to avoid frequent 'poll' payload
Or
Server side may push a WAP push to the client when messages are available, then the client wakes up and retreive the payload.
don't use Polling. Use Google Cloud Messaging. suseba answer references to gcm deprecated in the "Here" link.
Use GoogleCloudMessaging. comes with GooglePlayServices Library
Documentation : http://developer.android.com/google/gcm/client.html
and the source is: https://code.google.com/p/gcm/source/browse/#git%2Fgcm-client
you just need to import libraries

Two way communication between android and Server

i want a two communication between server and Android. From Android want to send my current location coordinates to server after each 10 minutes. i can send message or images to server at any time. Similarly from server i want to send data to Android whenever needed.
What should be the architecture of my application.
Communication from Android to server and Server to Android is independent of each other i should not ask it as a two way communication but infact i want communication from both sides to each other any time.
Should i use a Web service of any kind or just network sockets or Something else.
You can use websockets or...
Simply send data from phone to the server using normal request. When you want send something from server to telephone you can use push notifications (C2DM) and if you receive such push message you know that server has data for you and telephone can download it using normal request;-). It depends what data you want to send. Sometimes this approach will be good, sometimes it's better to use websockets, TCP sockets or even XMPP protocol ;-)
You can Use Acknowledge for the same. You need to Implement ACK/NACK Logic in your code. When you are sending Data just wait for ACK for a particular time period. If ACK is not received the you need to send NACK for the same. Here you need to use a session-id ( a kind of id for communication at both side, which can be any random number ).
You can use this Logic at both the side.

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