I have a school assignment about building a UDP based chat client on android. Now, my first idea was to make an activity that starts a service and the service handle all the networking and the activity all the input an output. But a have found a problem.
If i try to start the service so that the startCommand function starts and calls the socket.receive to start receiving network message, I can not bind the service so that i can pass input from the activity to the service (input = messages that the user want to send). It just hangs and a ANR exception is thrown. If i only bind it (so that receive is never called), it works like a Charm.
Maybe I'm not approaching this problem right. Or should it work to bind the service wen it's on a blocking receive call?
I did something like this once. I took the necessary data needed to track down the other device and fed it into an asyncTask where I kicked off a Runnable that basically kept a connection going on in the background.(This way you don't have to worry about binding) I found that instead of making your own socket connections its easier just to use Apache Mina or Netty. (No need to reinvent the wheel). If you just pass the data transmissions from the session running in the background to a List or a Queue and have an asyncTask check it and update the UI accordingly you should be all set for chatting. Maybe this isn't the best way, but it worked for me. Hope some of this helps.
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I want to get data from the server and store it in a cache regularly, even when the app is closed. I am not sure what is the correct way to do it. I have listed down the possible ways I can think of. Please let me know the correct or the best way to do it. Really appreciate any help.
Create an Activity and set a repeated alarm to call a service. The service should connect to the server and download the data in cache.
From a fragment, check the last time the cache was updated and then if the data is out-dated, connect to server in a background thread and update the cache.
You can Directly Use IntentService for Frequently Updating Data
IntentService is a subclass of android.app.Service class. A stated intent service allows to handle long running tasks without effecting the application UI thread. This is not bound to any activity so, it is not getting effected for any change in activity lifecycle. Once IntentService is started, it handles each Intent using a worker thread and stops itself when it runs out of work.
IntentService would be an best solution, If you have an work queue to process. For example, if your application using analytics you will likely to send event name and related parameter to your tracking server for each user generated event. Although each event means a tiny piece of data, creating networking request on each click will result an overhead to your application
For implementation : Updating Data from Server Using Intent Serive
Do take a look at Android Sync Adapter Framework.
https://developer.android.com/training/sync-adapters/index.html
Hope this helps.
My app has a UI and a connection is made to a bluetooth device which is periodically sending barcode scan data to my app. I then want to cache this data in a sqlite db and have another process push this data up to a web server.
I have managed to get the UI and bluetooth scan process separated by using an Intent Service for the scanner component... The thread in the intent service connects to the bluetooth device and loops endlessly pulling in new scan data as it comes... communicating with the UI via broadcast messages as it needs to.
So now I need to handle storing the data in a sqlite db and pushing it up to the Internet.
I'm thinking I can insert a db row directly in the intent service loop I already have working for the bluetooth data... would I do that by firing of an async task or something like that?
Then, would I have a completely different intent service running and looping endlessly checking for new records to be processed and pushed up to my web server via an http post?
I guess the main reason I'm thinking of using intent services is that they seem to keep running even if I lock my phone and put it in my pocket... has worked so far for the bluetooth barcode scanner... can scan away happily with my phone locked and in my pocket.
I also need to handle the reality that internet won't always be available... hence the sqlite db... kind of like a safe buffer to store data until it can eventually be pushed up to the Web server.
Am I going down the right path? I'm really new to Android development and even after much research I'm still unsure about my approach.
You can store data or communicate from IntentService onHandleIntent() directly. You don't need to run it in separate thread, unless you want reading bluetooth to continue ASAP.
Handling everything in an infinite loop smells. Also keeping service alive depends on few factors. If IntentService dies, it won't be restored because by default IntentService.onStartCommand implicitly returns START_NOT_STICKY, or START_REDELIVER_INTENT if you call setIntentRedelivery(true) on this service. Check Service javadoc for more info.
If you can scan bluetooth periodically then I would consider kind of scheduler. For that you would probably need to implement Service, not IntentService and handle background thread yourself. Alternatively, you could use a Timer. These are more hints, not ready solution. Since you asked about direction, I assume you will investigate solutions yourself.
Depending on handled data you could separate DB operations and network to separate services. Think about them as modules which are decoupled. You will benefit maintaing this code in the future and in case one service goes down due to any reason, the rest will keep working. It depends on data size because it's not a good practise to push heavy data between service/activities(data is serialised and deserialised every time it is sent).
If DB is just a buffer/queue then maybe use it directly after reading bluetooth data. In other words queue data for sending. Create second service for HTTP communications. Don't push entire data to second service, just inform it about(knock the door :)) and let HTTP service access DB by itself. I would wrap DB in ContentProvider and access it from services.
There are probably different techniques out there too, but that's what I thought about it in the first place.
I've tried searching around and I can't find a good answer that makes sense.
Basically when the activity first starts it should connect to a server and continually listen for a message. When it gets it, it'll parse it and if it's a particular message, close the connection and then do some other stuff. I should also be able to close it if the user pushes a button.
I tried searching around and I honestly can't tell if I should use servlets or services or what (edit: or how to use them). I do know that it probably needs to be on it's own thread.
So what should I use?
Edit: I'm not sure how to use the servers/services/etc. to make it happen
An IntentService is what you're gonna want. It's the easiest to implement and it's perfect for network operations. It automatically handles running the service in its own thread. Once you establish a connection with the server, it should stay open until you respond with some message from the server.
Hey I need to implement a infinite loop for receiving commands through socket and updating status in my android app and want that thread to be running even if application is closed. So I need to know that what I'm thinking is optimal solution or not... I am planning to make a service which create a thread which will look for commands and this class is also Observable so the activity can get updates of status from it. Kindly suggest your way or if you think this is right solution. Thanks.
Running things in background is usually a bad idea(battery life), especially if using data services(data plan costs). What you need is indeed a service, but start your updating status thread only when you receive a user present broadcast and stop it when the device goes to sleep(I think it's enough just not to request a wake lock and not use startForeground()).
I am new to Android development and am not sure of the best way to go about handling the following problem.
Background:
I have a TCP client running on android talking to a server. this is up and running just fine however when moving to the next step i am unsure of what to do.
Problem:
I have a UI that draws based on a users touch. I need for the tcp client running on the phone to send the coordinates and some other data to the server. Also there are multiple activities in this process that would be sending data.
What would be the best way to handle this?
Here are some of my thoughts.
1) A class that would have a Runnable client that works on another thread (I think its is an invalid solution because it would not be easy to use the same connection on multiple activities)
2) A local service that can the main activity can start and the rest of the activities can bind to it and send data to it.
If the correct answer is number 2 I am a little confused on how a service like that would work. What I am thinking is that in the OnCreate() method of the service it will launch a tcp connection with the server. Once the socket connection is established I am a bit unsure of how to actually keep in communication with the service and give it the data it needs to send over the client.
You would start the service with startService(). Include in the Intent extras that contain your data to send to the server. The service would retrieve these extras in onStartCommand() and would have a background thread actually send the data.
Be sure to stop the service when you are done with it.