Thanks Dianne for the clarification. I always thought that every task
should have been performed in a native android component, was it an
activity or a service.
I am quite curious about this topic.
Now, let's assume that his application does not need to fetch the data
while in background, and that in his singleton class runs a thread
that reads from the stream.
What is going to happen when the application goes in background
because, for example, the user receives a phone call?
>From my understanding (which may be very poor), the onStop() method of
the visible activity gets called BUT the process will still be active,
and with that the thread that reads from the stream. The singleton
will be destroyed only when the system needs resources to be allocated
for another application and it chooses our app as the one to be
killed. On the other hand, in case no resources are needed, the
singleton will still be around fetching data from the stream.
Not using a service will make the connection "available to be killed"
if the application goes background.
Is that correct?
And, if we want to close the connection when the application is no
longer visible, where should the connection be closed?
The onStop() gets called when the app goes background but also when
the activity gets destroyed because the user pressed the back button
to get to a previous activity (and in this case we don't want to close
the connection).
Sorry to bother, but I am working on similar stuff and I need to clear
my head a bit :-)
Thanks again for the support,
Federico
On Tue, Apr 17, 2012 at 4:10 AM, Dianne Hackborn <[email protected]> wrote:
> You don't need a service. And please please don't use startService() unless
> you really want to use up the user's resources with your app trying to run
> when they are not in it. Way too many apps I see abuse resources and keep
> themselves running in the background and thus just sucks.
>
> Just make a singleton that manages the stream, which any part of your code
> that wants it can access.
>
> On Mon, Apr 16, 2012 at 12:10 PM, Federico Paolinelli <[email protected]>
> wrote:
>>
>> Another approach that you could follow is to host the tcp connection
>> inside a service
>> (http://developer.android.com/reference/android/app/Service.html)
>>
>> You can then access the service from any activity you want using the
>> binding pattern or through intents.
>> Just remember that your app may continue to live in background, and your
>> service will still be running unless the os kills it. It's up to you to
>> disconnect if the activities go in background or if you want to notify the
>> user that the connection is still up and running.
>>
>> Remember also that service runs in the ui thread, so you will likely need
>> to run a different thread inside the service.
>>
>> Hope this helps,
>>
>> Federico
>>
>>
>>
>>
>> Il giorno lunedì 16 aprile 2012 18:31:09 UTC+2, Tonez ha scritto:
>>>
>>> Hi Everyone,
>>>
>>> I'm building an Android app which uses TCP sockets to communicate with
>>> a .net server application. The android app as a whole relies quite
>>> heavily on TCP and as such nearly all the features in the app require
>>> writing to and listening from a socket stream. I'm trying to
>>> determine what the best design approach is for having more than one
>>> activity utilize a live active socket.
>>>
>>> I've recently just finished building an iPhone version of this app,
>>> the way in which I got each feature (different view controllers) to
>>> use one live active socket connection was by passing the live socket
>>> instance to each view controller, each view controller would then
>>> retain ownership of that socket and as such the delegate methods which
>>> fire when a transmission is received work as expected. Trying to
>>> simulate this design in Android is proving to be a pain because I
>>> can't pass a live socket instance to another activity as part of an
>>> intent parameter.
>>>
>>> If I wanted to have activity A listen for incoming TCP data, and then
>>> navigate to Activity B but then have activity B send TCP data to
>>> the .net server and of-course spawn a new thread to listen for
>>> incoming TCP data - what would be the best approach to achieve this?
>>>
>>> At the moment what I have is as follows: activity A spawns a new
>>> thread listening for incoming TCP data, activity A can communicate
>>> with the .net server perfectly fine. When I navigate to activity B
>>> and then want to communicate with the .net server - creating a new
>>> socket instance and then listening for incoming data results in
>>> activity A's readLine() method receiving the data. Which makes sense,
>>> it's still running - but obviously the goal is to have activity B
>>> receive this data.
>>>
>>> An alternative approach I tried was to close down the TCP socket I
>>> have in activity A when opening up another TCP socket connection when
>>> I need to use TCP in activity B - although this somewhat works it
>>> really feels like the wrong way to go about it.
>>>
>>> And lastly, one other approach I've thought of is to have one activity
>>> handling all TCP comms with the .net server and contain all the
>>> functionality in this one activity by swapping out .xml layout files
>>> when necessary. Obviously this will result in one massive .java file
>>> and again is a route which feels wrong.
>>>
>>> Any advice on how I can go about designing my app given that I want to
>>> use TCP functionality in every activity would be greatly appreciated.
>>>
>>> Many thanks,
>>>
>>> Tonez
>>
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>
>
>
>
> --
> Dianne Hackborn
> Android framework engineer
> [email protected]
>
> Note: please don't send private questions to me, as I don't have time to
> provide private support, and so won't reply to such e-mails. All such
> questions should be posted on public forums, where I and others can see and
> answer them.
>
> --
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--------
Federico
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