Re: [android-developers] android design considerations: AsynchTask vs Service (IntentService?)
Dianne, With all due respect, HandlerThread or Thread do NOT convey the message that they can be used with the UI in the same way that an AsyncTask does. In fact even a small para saying something like AsyncTask runs as a separate thread and does interact with the Activity's lifecycle. It is associated with the instance that executed the AsyncTask, however the onProgress and onResult are called in the main UI thread that deals with the currently active instance which could be different than the one that executed the AsyncTask. Thus the developer must ensure that any reference to the Activity or UI components are not stale. would help, IMHO. I think we are beating a dead horse here and way off topic for the OP, so I will stop... On Sun, Oct 3, 2010 at 1:13 AM, Dianne Hackborn hack...@android.com wrote: On Sat, Oct 2, 2010 at 3:39 PM, Prakash Iyer thei...@gmail.com wrote: Each his own. Try writing a AsyncTask that say lives for more than 10s and in the final result say updates a text field. Now before the AsyncTask completes, just change the orientation. I'd bet most developers would assume the text field will get updated. Most developers would be wrong as the AsyncTask's onResult will be calling the original object's (the one that did the execute) text field and not the one that is currently displayed. Can you make sure this works? Yes! Should this be documented? I would think it is absolutely essential. This has *nothing* to do with AsyncTask, this is all about the peculiarities of Activity. You will run into the same issue if you use HandlerThread, a raw Thread()... heck, you'd even have the issue if you didn't use another thread at all but just Handler.postDelayedMessage(). This behavior is documented in the material Activity; it doesn't make any sense to try to document this in every other generic facility for asynchronicity just because if you use that with an Activity you will need to understand how Activity instances can be fairly transient. And what you need to do with AsyncTask is *different* depending on where you are using it -- in an Activity, or a Service, or a View, or whatever. They each have their own sometimes subtle details about lifecycle that you need to understand when introducing asynchronicity. AsyncTask can't try to document exactly how to use it when combined with every other possible facility. -- Dianne Hackborn Android framework engineer hack...@android.com 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. -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.comandroid-developers%2bunsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] android design considerations: AsynchTask vs Service (IntentService?)
On Fri, Oct 1, 2010 at 2:07 PM, Prakash Iyer thei...@gmail.com wrote: Service, OTOH, is designed to work in the background without requiring user interaction. Problem is that for your Activity to display the results it must somehow interact with your service. Ideally you will want to spawn the service off in a separate process and use either Intents or AIDL to communicate back progress to the Activity. The vast majority of the time, there is no need to run the service in a separate process and thus deal with all of the additional complexity of AIDL and such. As another poster mentioned, IntentService is very useful. Also AsyncTask vs. Service is the wrong question. These are almost totally orthogonal to each other -- you very often may use an AsyncTask as part of implementing a service for example. And if your service is running in the same process as your activity, it is very easy to just bind to it from the activity, call on to it to get its current state, and supply a callback for when the state changes, just using normal Java coding. -- Dianne Hackborn Android framework engineer hack...@android.com 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. -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] android design considerations: AsynchTask vs Service (IntentService?)
I'm not sure I agree with your comment that it is the wrong question. In fact your explanation of how a majority of the cases a Service runs in the same process is precisely why most people will consider these as alternatives. I was trying to point out to the OP that if the OP ever wanted to create something that lived independent of the UI and/or was planned to be used by more than one activity independently developed/distributed, a service would be a better choice... IMHO the AsyncTask is notoriously poorly documented. It has some really strange interactions with the Activity lifecycle... As some one pointed out the IntentService is probably a better choice in many cases. Which again brings to question the orthogonality of AsyncTask Service... On Sat, Oct 2, 2010 at 5:09 AM, Dianne Hackborn hack...@android.com wrote: On Fri, Oct 1, 2010 at 2:07 PM, Prakash Iyer thei...@gmail.com wrote: Service, OTOH, is designed to work in the background without requiring user interaction. Problem is that for your Activity to display the results it must somehow interact with your service. Ideally you will want to spawn the service off in a separate process and use either Intents or AIDL to communicate back progress to the Activity. The vast majority of the time, there is no need to run the service in a separate process and thus deal with all of the additional complexity of AIDL and such. As another poster mentioned, IntentService is very useful. Also AsyncTask vs. Service is the wrong question. These are almost totally orthogonal to each other -- you very often may use an AsyncTask as part of implementing a service for example. And if your service is running in the same process as your activity, it is very easy to just bind to it from the activity, call on to it to get its current state, and supply a callback for when the state changes, just using normal Java coding. -- Dianne Hackborn Android framework engineer hack...@android.com 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. -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.comandroid-developers%2bunsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] android design considerations: AsynchTask vs Service (IntentService?)
AsyncTask is excellently documented: http://developer.android.com/reference/android/os/AsyncTask.html http://developer.android.com/reference/android/os/AsyncTask.htmlAsyncTask has no interaction with the Activity lifecycle, except for that which you introduce with your own code. It's for precisely this reason that AsyncTask and Service are mostly orthogonal: An AsyncTask is helpful way of delegating work onto a thread other than the main thread; a Service exposes a component lifecycle so that a UI-free operation can be managed by the system. Tom. On 2 October 2010 22:20, Prakash Iyer thei...@gmail.com wrote: I'm not sure I agree with your comment that it is the wrong question. In fact your explanation of how a majority of the cases a Service runs in the same process is precisely why most people will consider these as alternatives. I was trying to point out to the OP that if the OP ever wanted to create something that lived independent of the UI and/or was planned to be used by more than one activity independently developed/distributed, a service would be a better choice... IMHO the AsyncTask is notoriously poorly documented. It has some really strange interactions with the Activity lifecycle... As some one pointed out the IntentService is probably a better choice in many cases. Which again brings to question the orthogonality of AsyncTask Service... On Sat, Oct 2, 2010 at 5:09 AM, Dianne Hackborn hack...@android.comwrote: On Fri, Oct 1, 2010 at 2:07 PM, Prakash Iyer thei...@gmail.com wrote: Service, OTOH, is designed to work in the background without requiring user interaction. Problem is that for your Activity to display the results it must somehow interact with your service. Ideally you will want to spawn the service off in a separate process and use either Intents or AIDL to communicate back progress to the Activity. The vast majority of the time, there is no need to run the service in a separate process and thus deal with all of the additional complexity of AIDL and such. As another poster mentioned, IntentService is very useful. Also AsyncTask vs. Service is the wrong question. These are almost totally orthogonal to each other -- you very often may use an AsyncTask as part of implementing a service for example. And if your service is running in the same process as your activity, it is very easy to just bind to it from the activity, call on to it to get its current state, and supply a callback for when the state changes, just using normal Java coding. -- Dianne Hackborn Android framework engineer hack...@android.com 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. -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.comandroid-developers%2bunsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.comandroid-developers%2bunsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] android design considerations: AsynchTask vs Service (IntentService?)
Each his own. Try writing a AsyncTask that say lives for more than 10s and in the final result say updates a text field. Now before the AsyncTask completes, just change the orientation. I'd bet most developers would assume the text field will get updated. Most developers would be wrong as the AsyncTask's onResult will be calling the original object's (the one that did the execute) text field and not the one that is currently displayed. Can you make sure this works? Yes! Should this be documented? I would think it is absolutely essential. On Sat, Oct 2, 2010 at 6:25 PM, Tom Gibara tomgib...@gmail.com wrote: AsyncTask is excellently documented: http://developer.android.com/reference/android/os/AsyncTask.html http://developer.android.com/reference/android/os/AsyncTask.htmlAsyncTask has no interaction with the Activity lifecycle, except for that which you introduce with your own code. It's for precisely this reason that AsyncTask and Service are mostly orthogonal: An AsyncTask is helpful way of delegating work onto a thread other than the main thread; a Service exposes a component lifecycle so that a UI-free operation can be managed by the system. Tom. On 2 October 2010 22:20, Prakash Iyer thei...@gmail.com wrote: I'm not sure I agree with your comment that it is the wrong question. In fact your explanation of how a majority of the cases a Service runs in the same process is precisely why most people will consider these as alternatives. I was trying to point out to the OP that if the OP ever wanted to create something that lived independent of the UI and/or was planned to be used by more than one activity independently developed/distributed, a service would be a better choice... IMHO the AsyncTask is notoriously poorly documented. It has some really strange interactions with the Activity lifecycle... As some one pointed out the IntentService is probably a better choice in many cases. Which again brings to question the orthogonality of AsyncTask Service... On Sat, Oct 2, 2010 at 5:09 AM, Dianne Hackborn hack...@android.comwrote: On Fri, Oct 1, 2010 at 2:07 PM, Prakash Iyer thei...@gmail.com wrote: Service, OTOH, is designed to work in the background without requiring user interaction. Problem is that for your Activity to display the results it must somehow interact with your service. Ideally you will want to spawn the service off in a separate process and use either Intents or AIDL to communicate back progress to the Activity. The vast majority of the time, there is no need to run the service in a separate process and thus deal with all of the additional complexity of AIDL and such. As another poster mentioned, IntentService is very useful. Also AsyncTask vs. Service is the wrong question. These are almost totally orthogonal to each other -- you very often may use an AsyncTask as part of implementing a service for example. And if your service is running in the same process as your activity, it is very easy to just bind to it from the activity, call on to it to get its current state, and supply a callback for when the state changes, just using normal Java coding. -- Dianne Hackborn Android framework engineer hack...@android.com 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. -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.comandroid-developers%2bunsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.comandroid-developers%2bunsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.comandroid-developers%2bunsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to
Re: [android-developers] android design considerations: AsynchTask vs Service (IntentService?)
AsyncTasks can be used in a number of contexts, not only in Activities. And where they are used in activities, there are many way of plumbing them to the activity lifecycle. Here are three scenarios that I would generally use AsyncTasks for (rather than services): 1) Dynamically rendering an image for the UI (here I would usually let the task run to completion and then discard the bitmap if the Activity had been destroyed). 2) Loading thumbnails from a web server (here I might explicitly cancel the task when the activity is destroyed) 3) Logging a user into a server (here I typically keep the task running and maintain a static reference to the 'current' activity instance) My point here is that the range of possible ways of using AsyncTask is broad, and the best way is heavily dependent on the specific case, so it ceases to be something that can be adequately covered in the javadocs. It's better suited to a book on Android development in my opinion. Tom. On 2 October 2010 23:39, Prakash Iyer thei...@gmail.com wrote: Each his own. Try writing a AsyncTask that say lives for more than 10s and in the final result say updates a text field. Now before the AsyncTask completes, just change the orientation. I'd bet most developers would assume the text field will get updated. Most developers would be wrong as the AsyncTask's onResult will be calling the original object's (the one that did the execute) text field and not the one that is currently displayed. Can you make sure this works? Yes! Should this be documented? I would think it is absolutely essential. On Sat, Oct 2, 2010 at 6:25 PM, Tom Gibara tomgib...@gmail.com wrote: AsyncTask is excellently documented: http://developer.android.com/reference/android/os/AsyncTask.html http://developer.android.com/reference/android/os/AsyncTask.htmlAsyncTask has no interaction with the Activity lifecycle, except for that which you introduce with your own code. It's for precisely this reason that AsyncTask and Service are mostly orthogonal: An AsyncTask is helpful way of delegating work onto a thread other than the main thread; a Service exposes a component lifecycle so that a UI-free operation can be managed by the system. Tom. On 2 October 2010 22:20, Prakash Iyer thei...@gmail.com wrote: I'm not sure I agree with your comment that it is the wrong question. In fact your explanation of how a majority of the cases a Service runs in the same process is precisely why most people will consider these as alternatives. I was trying to point out to the OP that if the OP ever wanted to create something that lived independent of the UI and/or was planned to be used by more than one activity independently developed/distributed, a service would be a better choice... IMHO the AsyncTask is notoriously poorly documented. It has some really strange interactions with the Activity lifecycle... As some one pointed out the IntentService is probably a better choice in many cases. Which again brings to question the orthogonality of AsyncTask Service... On Sat, Oct 2, 2010 at 5:09 AM, Dianne Hackborn hack...@android.comwrote: On Fri, Oct 1, 2010 at 2:07 PM, Prakash Iyer thei...@gmail.com wrote: Service, OTOH, is designed to work in the background without requiring user interaction. Problem is that for your Activity to display the results it must somehow interact with your service. Ideally you will want to spawn the service off in a separate process and use either Intents or AIDL to communicate back progress to the Activity. The vast majority of the time, there is no need to run the service in a separate process and thus deal with all of the additional complexity of AIDL and such. As another poster mentioned, IntentService is very useful. Also AsyncTask vs. Service is the wrong question. These are almost totally orthogonal to each other -- you very often may use an AsyncTask as part of implementing a service for example. And if your service is running in the same process as your activity, it is very easy to just bind to it from the activity, call on to it to get its current state, and supply a callback for when the state changes, just using normal Java coding. -- Dianne Hackborn Android framework engineer hack...@android.com 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. -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.comandroid-developers%2bunsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -- You received this message
Re: [android-developers] android design considerations: AsynchTask vs Service (IntentService?)
item #5 seems not user friendly to me. assuming that user can open other applications on the phone and since that the sync takes 10-20 minutes i suggest initiating an asynctask in a service. If you use a service, android will try hard not kill your application process. On Tue, Sep 28, 2010 at 11:50 PM, Tia cyclechic...@gmail.com wrote: I'm designing an android app which will need todo the following steps: 1. user pushes a button or otherwise indicates to synch data. 2. synch process will use REST web services to move data to and from the server. 3. the data will be stored locally in a sqlite database. 4. the synch process should provide status updates/messages to the UI 5. the user should not be allowed to wander off to other parts of the application and do more work during the synch process. The first time the synch process runs, it may take 10-20 minutes. After the initial synch, less data will be transferred and stored and I expect the process to take 1-2 minutes or less. I've been doing a lot of reading about android's AsychTask and various examples of using a Service ... But I don't fully understand the design considerations and trade-offs of choosing one design over the other. I currently have my demo project stubbed out using an AsychTask. After watching (most of) Developing Android REST client applications: http://code.google.com/events/io/2010/sessions/developing-RESTful-android-apps.html# I'm left confused the design patterns described here feel overly complex, perhaps because I just don't get it yet. Would love to hear from some more experienced android developers out there who have already wrestled with these questions. -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] android design considerations: AsynchTask vs Service (IntentService?)
On Sat, Oct 2, 2010 at 3:39 PM, Prakash Iyer thei...@gmail.com wrote: Each his own. Try writing a AsyncTask that say lives for more than 10s and in the final result say updates a text field. Now before the AsyncTask completes, just change the orientation. I'd bet most developers would assume the text field will get updated. Most developers would be wrong as the AsyncTask's onResult will be calling the original object's (the one that did the execute) text field and not the one that is currently displayed. Can you make sure this works? Yes! Should this be documented? I would think it is absolutely essential. This has *nothing* to do with AsyncTask, this is all about the peculiarities of Activity. You will run into the same issue if you use HandlerThread, a raw Thread()... heck, you'd even have the issue if you didn't use another thread at all but just Handler.postDelayedMessage(). This behavior is documented in the material Activity; it doesn't make any sense to try to document this in every other generic facility for asynchronicity just because if you use that with an Activity you will need to understand how Activity instances can be fairly transient. And what you need to do with AsyncTask is *different* depending on where you are using it -- in an Activity, or a Service, or a View, or whatever. They each have their own sometimes subtle details about lifecycle that you need to understand when introducing asynchronicity. AsyncTask can't try to document exactly how to use it when combined with every other possible facility. -- Dianne Hackborn Android framework engineer hack...@android.com 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. -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
[android-developers] android design considerations: AsynchTask vs Service (IntentService?)
I'm designing an android app which will need todo the following steps: 1. user pushes a button or otherwise indicates to synch data. 2. synch process will use REST web services to move data to and from the server. 3. the data will be stored locally in a sqlite database. 4. the synch process should provide status updates/messages to the UI 5. the user should not be allowed to wander off to other parts of the application and do more work during the synch process. The first time the synch process runs, it may take 10-20 minutes. After the initial synch, less data will be transferred and stored and I expect the process to take 1-2 minutes or less. I've been doing a lot of reading about android's AsychTask and various examples of using a Service ... But I don't fully understand the design considerations and trade-offs of choosing one design over the other. I currently have my demo project stubbed out using an AsychTask. After watching (most of) Developing Android REST client applications: http://code.google.com/events/io/2010/sessions/developing-RESTful-android-apps.html# I'm left confused the design patterns described here feel overly complex, perhaps because I just don't get it yet. Would love to hear from some more experienced android developers out there who have already wrestled with these questions. -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] android design considerations: AsynchTask vs Service (IntentService?)
Not sure I am experienced but I did use both AsncTask and Service, so here is my opinion. AyncTask works great - until the user does something to visually alter your app, e.g. changes orientation or goes to the home screen. Reason is that the AsyncTask will most likely be referring to UI elements in the original Activity instance and you will suddenly not see anything happening. Google on the forum and you will see a discussion on a persistent dialog that tells you the problem and one solution. Also, once the Activity is out of view, I am guessing the OS can destroy it and there isn't much control given to AsyncTask. Service, OTOH, is designed to work in the background without requiring user interaction. Problem is that for your Activity to display the results it must somehow interact with your service. Ideally you will want to spawn the service off in a separate process and use either Intents or AIDL to communicate back progress to the Activity. So, if your task can be paused and restarted along with the main Activity, AsyncTask might work quite well. If not, Service might be the way to go. You said the initial sync can take 15-20 min, so be sure you understand how an AsyncTask interacts with Activity if it moved away from the foreground coz' unless these are your real friends or you are showing something really compelling, people will move on... On Wed, Sep 29, 2010 at 2:50 AM, Tia cyclechic...@gmail.com wrote: I'm designing an android app which will need todo the following steps: 1. user pushes a button or otherwise indicates to synch data. 2. synch process will use REST web services to move data to and from the server. 3. the data will be stored locally in a sqlite database. 4. the synch process should provide status updates/messages to the UI 5. the user should not be allowed to wander off to other parts of the application and do more work during the synch process. The first time the synch process runs, it may take 10-20 minutes. After the initial synch, less data will be transferred and stored and I expect the process to take 1-2 minutes or less. I've been doing a lot of reading about android's AsychTask and various examples of using a Service ... But I don't fully understand the design considerations and trade-offs of choosing one design over the other. I currently have my demo project stubbed out using an AsychTask. After watching (most of) Developing Android REST client applications: http://code.google.com/events/io/2010/sessions/developing-RESTful-android-apps.html# I'm left confused the design patterns described here feel overly complex, perhaps because I just don't get it yet. Would love to hear from some more experienced android developers out there who have already wrestled with these questions. -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.comandroid-developers%2bunsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
Re: [android-developers] android design considerations: AsynchTask vs Service (IntentService?)
You will more than likely need a service. It'll save you a lot of work later on. You would start your service when your app starts, then your activities bind to is and communicate via something like AIDL. So the activity can tell the service to start a sync. And when the service is done, it can send off an intent, or an AIDL callback method. On Fri, Oct 1, 2010 at 2:07 PM, Prakash Iyer thei...@gmail.com wrote: Not sure I am experienced but I did use both AsncTask and Service, so here is my opinion. AyncTask works great - until the user does something to visually alter your app, e.g. changes orientation or goes to the home screen. Reason is that the AsyncTask will most likely be referring to UI elements in the original Activity instance and you will suddenly not see anything happening. Google on the forum and you will see a discussion on a persistent dialog that tells you the problem and one solution. Also, once the Activity is out of view, I am guessing the OS can destroy it and there isn't much control given to AsyncTask. Service, OTOH, is designed to work in the background without requiring user interaction. Problem is that for your Activity to display the results it must somehow interact with your service. Ideally you will want to spawn the service off in a separate process and use either Intents or AIDL to communicate back progress to the Activity. So, if your task can be paused and restarted along with the main Activity, AsyncTask might work quite well. If not, Service might be the way to go. You said the initial sync can take 15-20 min, so be sure you understand how an AsyncTask interacts with Activity if it moved away from the foreground coz' unless these are your real friends or you are showing something really compelling, people will move on... On Wed, Sep 29, 2010 at 2:50 AM, Tia cyclechic...@gmail.com wrote: I'm designing an android app which will need todo the following steps: 1. user pushes a button or otherwise indicates to synch data. 2. synch process will use REST web services to move data to and from the server. 3. the data will be stored locally in a sqlite database. 4. the synch process should provide status updates/messages to the UI 5. the user should not be allowed to wander off to other parts of the application and do more work during the synch process. The first time the synch process runs, it may take 10-20 minutes. After the initial synch, less data will be transferred and stored and I expect the process to take 1-2 minutes or less. I've been doing a lot of reading about android's AsychTask and various examples of using a Service ... But I don't fully understand the design considerations and trade-offs of choosing one design over the other. I currently have my demo project stubbed out using an AsychTask. After watching (most of) Developing Android REST client applications: http://code.google.com/events/io/2010/sessions/developing-RESTful-android-apps.html# I'm left confused the design patterns described here feel overly complex, perhaps because I just don't get it yet. Would love to hear from some more experienced android developers out there who have already wrestled with these questions. -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en -- ~ Jeremiah:9:23-24 Android 2D MMORPG: http://developingthedream.blogspot.com/, http://diastrofunk.com, http://www.youtube.com/user/revoltingx -- You received this message because you are subscribed to the Google Groups Android Developers group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
