Disconnected Mobile App data sync issue

[shahzad.rashid]

Hi,

I am working on a disconnected mobile app to collect some field data. I have some issue with Data Sync and wondering if somebody could explain if this is correct behaviour of the App settings I selected?
I've a UX component which is packaged/distributed as an Android App using the Phone Gap Build. I've tried using following two settings:

Option 1:
UX component properties
Restore Variable from Local Storage = True
Restore data in List control from Local storage or (File System) = True

List control Properties
Persist data to Local Storage (or File System) = True
Persist where = Local storage

Result: I enter data while application is offline, then connect to network and complete Data Sync, all data Synced to the server as expected.


Option 2:
UX component properties
Restore Variable from Local Storage = True
Restore data in List control from Local storage or (File System) = True

List control Properties
Persist data to Local Storage (or File System) = True
Persist where = FileSystem

Result: I enter data while application is offline, then connect to network and complete Data Sync, all data collected offline is lost/overwritten by the data from the server.
Am I doing something wrong here?

I would also appreciate if somebody could explain what is the correct option to use for unlimited list control data storage on local device. My understanding is that "Local Storage" option have only 5MB limit and "FileSystem" allows unlimited data storage. But I am little confused about storage limits using the Phone Gap Build.

Many thanks for your help.

Shaz

[jgrannis]

Re: Disconnected Mobile App data sync issue

Option 2 should be working how you are imagining it should work and the data storage limit is basically limited to the size of your device's storage.

When you connect back to the network, what do you call to start the sync process?
What is the Synchronization Policy that you have set up in the List Builder's Detail View tab for the list?

I would probably NOT check the server-to-client synchronization.
I would manage my client-to-server sync and then maybe on the afterSynchronizeList event, call an incremental refresh.

[dbinns]

Re: Disconnected Mobile App data sync issue

I have found that switching from local storage to filesystem can cause some issues. In list properties change the list version. In properties change the persisted version number.

You also need to have the right phonegap plugins for filesystem. Which I believe are File System, Device and File.

[shahzad.rashid]

Re: Disconnected Mobile App data sync issue

Lets suppose I've 5 records on the server and I collect 2 more records offline then after the sync there should be 7 records in total on the server. This is working fine using option 1, but using option 2, I lose 2 newly offline collected records after the sync and I can only see the 5 records both on the server and on mobile device.

On Sync I am calling following two methods:
{dialog.object}.saveListEdits('LIST1',{rows: 'allRows'});
{dialog.object}.refreshListData('LIST1');

There is no Synchronization policy setup in List Builder's Detail View.

So am I right in understanding that, if I use Local Storage option and distribute Mob App using Phone Gap Build, its not limited to 5MB cache storage? Its only limited to the mobile devices storage?

Thanks,

[jgrannis]

Re: Disconnected Mobile App data sync issue

Add the incremental mode to your refreshListData
And again, I would add the refresh code to the afterSynchronizeList event.
The refresh is probably getting sent to the device before the saveListEdits has finished.

[Davidk]

Re: Disconnected Mobile App data sync issue

So am I right in understanding that, if I use Local Storage option and distribute Mob App using Phone Gap Build, its not limited to 5MB cache storage? Its only limited to the mobile devices storage?

No... that's not right. Local Storage is limited to approx. 5Mb of volatile storage. If something in your device needs Local Storage... it will take it. FileSystemStorage is using whatever the internal storage the device has available.

This might help a bit... although the doc, again, is wrong...
https://www.alphasoftware.com/docume...rage/index.xml

Persisting Data to Local Storage
When you build an application for disconnected operation you need to be sure that the data in the application is persisted to Local Storage so that edits that are made to any data are not lost if the application is restarted before the user has had a chance to synchronize the data with the server.

This is misleading... and just adds confusion. I wish Alpha would fix this stuff.

You've not mentioned what version/build of Alpha you're using.... or the version of PGB you're using... or the back end database you're using... or the Android device / Android OS. Lots of info missing that could affect stuff.

I've just tested an Android app build under the pre-release 4966_5071, PGB cli-7.1.0. The List Control is set to use FileSystemStorage, the UX is set to Restore data in List Controls... and everything else (i.e. Sync policies) are the default settings. Nexus 7 running 6.0.1.

With Wifi shut off on the device... I can add/edit List data... shut down the app... turn Wifi on... start the App... Sync... and all edits and new List data is in my backend MySQL table.

[shahzad.rashid]

Re: Disconnected Mobile App data sync issue

Hi David,

Details below:

Alpha Version: 12.4.5.2
Build: 4770_5018
PGB cli-7.0.1
SQL Server 2008 Express

Please try following:

Turn Wifi off, restart the Device, stay offline and start the App, enter new records, turn Wifi On and Sync.

See if this replicates the problem I am having.

[shahzad.rashid]

Re: Disconnected Mobile App data sync issue

Sorry I missed a step:

Turn Wifi off, shut down the app, restart the Device, stay offline and start the App, enter new records, turn Wifi On and Sync.

[Davidk]

Re: Disconnected Mobile App data sync issue

Following your steps... no issues. What Android device, Android OS Version are you using?

I'll duplicate the same under Alpha 4770 and see what happens.

[Davidk]

Re: Disconnected Mobile App data sync issue

No issues under Alpha 4770 and PGB 7.0.1.

Your Alpha Dev is at 4770_5018. Is your Alpha Server at 4770_5018 as well?

[shahzad.rashid]

Re: Disconnected Mobile App data sync issue

Yes same Alpha Server Version ( I recently applied Alpha Security Alert Patch)

Device: Galaxy Tab S
Model: SM-T700
Android Version: 6.0.1

I've done further testing, please try this: turn off wifi, shut down the app, add new record, shut down the app again, open the app and recently added record will be gone.

You can also download and test my app from following link:
http://s3.amazonaws.com/android.phon..._1_4-debug.apk

[Davidk]

Re: Disconnected Mobile App data sync issue

Still no issues. Post the QRCode image... much easier to deal with... and I'll install your app.

[shahzad.rashid]

Re: Disconnected Mobile App data sync issue

May be it the issue of the selecting correct PhoneGap Plugins.

QR Code attached thanks.

HEADSE_QR.jpg

[Davidk]

Re: Disconnected Mobile App data sync issue

For some reason your app is producing the a File Write Error - Offline.

Here's what I'm seeing. While Offline... add a new record and Save. That record shows up in the List. Shut down your app. Start your app. That new record is not there.

Here is where Alpha starts to show it's untested code. The new record is added to the List... so you think everything is ok. But... even though Alpha knows there is an error... you'll only see it in debugging. There is no error that bubbles up to the user. This is terrible.

In my app, the record is still there... still marked with a blue triangle - which represents a new record waiting to be sync'd.

It's impossible to know what's wrong without seeing your app... the code being used... how it's set up... the plugins being used.

You should create a simple, List/Detail View only app... using all the standard buttons with their standard code... and test that.

Alpha_List_FileWirteErrorOffline.PNG

[dbinns]

Re: Disconnected Mobile App data sync issue

May be it the issue of the selecting correct PhoneGap Plugins.

QR Code attached thanks.

[ATTACH=CONFIG]44703[/ATTACH]

Which plugins are you using. You need Device to have access to the filesystem, and you need filesystem to access the filesystem.