Azure mobile services offline sync xamarin

This tutorial introduces the offline sync feature of Azure Mobile Apps for Xamarin. Offline sync allows end users to interact with a mobile app--viewing, adding, or modifying data--even when there is no network connection.

Changes are stored in a local database. Once the device is back online, these changes are synced with the remote service. This tutorial is based on the Xamarin. The quickstart solution for Xamarin. Forms contains the code to support offline sync, which just needs to be enabled. In this tutorial, you update the quickstart solution to turn on the offline features of Azure Mobile Apps. We also highlight the offline-specific code in the app.

If you do not use the downloaded quickstart solution, you must add the data access extension packages to your project.

azure mobile services offline sync xamarin

For more information about server extension packages, see Work with the. The offline sync code is included in the project by using C preprocessor directives. For Windows apps, you must also install the SQLite platform. Windows 8. Windows Phone 8. Although the quickstart does not contain a Universal Windows project, the Universal Windows platform is supported with Xamarin Forms. The offline sync functionality is in the TodoItemManager. Before any table operations can be performed, the local store must be initialized.

The local store database is initialized in the TodoItemManager class constructor by using the following code:. The DefineTable method creates a table in the local store that matches the fields in the provided type. The type doesn't have to include all the columns that are in the remote database.

It is possible to store a subset of columns. This class uses the local database for all create, read, update, and delete CRUD table operations. The sync context helps preserve table relationships by tracking and pushing changes in all tables a client app has modified when PushAsync is called. This sample uses simple error handling with the default sync handler.

A real application would handle the various errors like network conditions and server conflicts by using a custom IMobileServiceSyncHandler implementation. In the sample, the SyncAsync method is only called on start-up and when a sync is requested. To initiate a sync in an Android or iOS app, pull down on the items list; for Windows, use the Sync button. In a real-world application, you could also make the sync trigger when the network state changes.

When a pull is executed against a table that has pending local updates tracked by the context, that pull operation automatically triggers a preceding context push. When refreshing, adding, and completing items in this sample, you can omit the explicit PushAsync call. In the provided code, all records in the remote TodoItem table are queried, but it is also possible to filter records by passing a query id and query to PushAsync. With offline sync now enabled, run the client application at least once on each platform to populate the local store database.

Later, simulate an offline scenario and modify the data in the local store while the app is offline. In this section, modify the client project to simulate an offline scenario by using an invalid application URL for your backend. Alternatively, you can turn off network connections by moving your device to "Airplane mode. In the Solution Explorer, open the Constants.

Open the TodoItemManager. This catch block writes the exception message to the console, as follows:.Because of this, some apps will need to provide offline access, so that users or employees, can continue to work uninterrupted.

To do this, we need local data storage, commonly SQLite, and a way to update the server with changes and receive new changes, while we were offline. This can become complex, very quickly.

There are existing libraries out there for offline capabilities, such as Azure Mobile Clientbut they normally end up too restrictive, and is not designed for complex situations. However, once you see what needs to be done, you might understand why it is so hard to get right. To provide offline access we need 2-way bi-directional synchronization, and it is the hardest type of synchronization to implement, if you have multiple clients working on the same records.

What we are going through here, is bi-directional 2-way synchronization, on records that could be updated via multiple clients, at any point in time. But this process works for either scenario, just described.

Azure Mobile Apps with Xamarin Forms - Session 1

When you need to provide synchronization, there are many issues that can present. If you have control of the API, and this is a greenfield project, you are in luck. If not, then there are workarounds. Here are some of the issues you need to be aware of. Here is how you can setup your server data store and API. First lets look at the Mobile Client setup and how it connects to the server. The point to note here, is your app should know nothing, of the synchronization service or API.

It makes it incredibly easy then to shield your app from changes to the API and synchronization processes. The synchronization service will be the only service that even knows about your API, and your App Service can trigger a sync, either at intervals, or when each row is updated. That is up to you on the frequency required. This will relieve any performance hit, and provide you with a GUID primary key, which is fantastic for synchronization. If you want to know more about the clustered index, please take a look at my other post Creating SQL Azure Databaseand look at the Clustered Index section.

You want to add a deleted column to each table you are synchronizing. Otherwise you would have to send all rows to the server and compare which ones are no longer there anymore. Keeping this simple, you will want a LastUpdated column in your table, to track the last time the server updated it. Also, you will want a ClientLastUpdated timestamp, to mark, when the client recorded the data.

This can later be used to overwrite, if a client recorded data at a later stage, but synchronized last. For example, if a client record has their mobile phone number updated, then they come back a few minutes later and update again because they gave you the wrong one, but the data was entered by different people on 2 different devices, this can cause an issue. If the second correct time they updated, is synchronized before the first incorrect one, then when the incorrect one is synchronized, it will overwrite with the incorrect value.

This is why tracking ClientLastUpdated, is important. Ensure you lock your database row from reads and updates, while you read it and compare it, during your determination of the sync. The App Service will be updating data, directly to the local client database.

When a sync happens, it is best to lock all updates to the database, to avoid many potential issues.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I can create the table as the link attached says, the problem is that when I synchronize my data from my xamarin app it says that the resource does not exist or has been removed, that it has been changed or that it is temporarily unavailable.

I think the problem is some configuration or package or extension that I must install in this new app services but I cannot identify it.

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Learn more. Asked 6 months ago. Active 6 months ago. Viewed times. PushAsync ; await PatientTable. CancelAndUpdateItemAsync error. Operation discarded. Ivanrlg Ivanrlg 27 6 6 bronze badges. What does the structure of your new table look like? Does it have the id, createdAt, updatedAt, and deleted columns? EricHedstrom Hello, after many attempts I realized that the error is the database connection string that had a small error, once I corrected it, the synchronization started again as expected.

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azure mobile services offline sync xamarin

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Hot Network Questions. Question feed. Stack Overflow works best with JavaScript enabled.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. We recommend using Azure Mobile Apps for all new mobile backend deployments. Read this announcement to learn more about the pending deprecation of this service.

Learn about migrating your site to Azure App Service. This topic walks through the offline sync capabilities of Azure Mobile Services in the todo list quickstart app. Offline sync allows you to easily create apps that are usable even when the end user has no network access. If you don't have an account, you can sign up for an Azure trial and get up to 10 free mobile services that you can keep using even after your trial ends. For details, see Azure Free Trial.

If this is your first experience with Mobile Services, you should first complete Get started with Mobile Services. Azure Mobile Services offline sync allows end users to interact with a local database when the network is not accessible.

To use these features in your app, you initialize MobileServiceClient. SyncContext to a local store. This section walks through the offline sync related code in QSTodoService.

In Visual Studio, open the project that you completed in the Get started with Mobile Services tutorial. Open the file QSTodoService. Offline sync uses this sync table interface instead of IMobileServiceTable.

Offline Data Sync in Xamarin Forms by using Azure Mobile Service

When a sync table is used, all operations go to the local store and are only synchronized with the remote service with explicit push and pull operations. To get a reference to a sync table, the method GetSyncTable is used. To remove the offline sync functionality, you would instead use GetTable. Before any table operations can be performed, the local store must be initialized.

This is done in the InitializeStoreAsync method:. You can also provide a different local store implementation by implementing IMobileServiceLocalStore. The DefineTable method creates a table in the local store that matches the fields in the provided type, ToDoItem in this case. The type doesn't have to include all of the columns that are in the remote database--it is possible to store just a subset of columns. This overload of InitializeAsync uses the default conflict handler, which fails whenever there is a conflict.

To provide a custom conflict handler, see the tutorial Handling conflicts with offline support for Mobile Services. This method is a member of IMobileServicesSyncContext instead of the sync table because it will push changes across all tables. Only records that have been modified in some way locally through CUD operations will be sent to the server. PullAsync to pull data from a table on the server to the app.This tutorial introduces the offline sync feature of Azure Mobile Apps for Xamarin.

Offline sync allows end users to interact with a mobile app--viewing, adding, or modifying data--even when there is no network connection. Changes are stored in a local database. Once the device is back online, these changes are synced with the remote service. In this tutorial, you update the client project from the tutorial Create a Xamarin Android app to support the offline features of Azure Mobile Apps. If you do not use the downloaded quick start server project, you must add the data access extension packages to your project.

For more information about server extension packages, see Work with the. Azure Mobile App offline features allow you to interact with a local database when you are in an offline scenario. To use these features in your app, you initialize a SyncContext to a local store.

SQLite is used as the local store on the device.

azure mobile services offline sync xamarin

In this section, you break the connection to your Mobile App backend to simulate an offline situation. When you add data items, your exception handler tells you that the app is in offline mode. In this state, new items added in the local store and are synced to the mobile app backend when a push is executed in a connected state. Edit ToDoActivity. You can also demonstrate offline behavior by disabling wifi and cellular networks on the device or using airplane mode.

Press F5 to build and run the app. Notice your sync failed on refresh when the app launched. Enter new items and notice that push fails with a [CancelledByNetworkError] status each time you click Save. However, the new todo items exist in the local store until they can be pushed to the mobile app backend. In a production app, if you suppress these exceptions the client app behaves as if it's still connected to the mobile app backend.

Close the app and restart it to verify that the new items you created are persisted to the local store. Now you can browse to your SQL database table and its contents. Verify that the data in the backend database has not changed. In this section, reconnect the app to the mobile app backend.This tutorial introduces the offline sync feature of Azure Mobile Apps for Xamarin.

Offline sync allows end users to interact with a mobile app--viewing, adding, or modifying data--even when there is no network connection. Changes are stored in a local database.

Once the device is back online, these changes are synced with the remote service. In this tutorial, update the Xamarin. If you do not use the downloaded quick start server project, you must add the data access extension packages to your project.

For more information about server extension packages, see Work with the. Azure Mobile App offline features allow you to interact with a local database when you are in an offline scenario.

To use these features in your app, initialize a SyncContext to a local store. SQLite is used as the local store on the device. In this section, you break the connection to your Mobile App backend to simulate an offline situation. When you add data items, your exception handler tells you that the app is in offline mode. In this state, new items added in the local store and will be synced to the mobile app backend when push is next run in a connected state. You can also demonstrate offline behavior by disabling wifi and cellular networks on the device or using airplane mode.

Enter new items and notice that push fails with a [CancelledByNetworkError] status each time you click Save. However, the new todo items exist in the local store until they can be pushed to the mobile app backend. In a production app, if you suppress these exceptions the client app behaves as if it's still connected to the mobile app backend. Close the app and restart it to verify that the new items you created are persisted to the local store. Now you can browse to your SQL database table and its contents.

Verify that the data in the backend database has not changed. In this section, reconnect the app to the mobile app backend.I need to implement offline functionality for a Xamarin Forms app, just retrieve the data from the server and push it into an sqllite database and then work with that data.

I have only found tutorials using Azure, but in my case I need to work with a remote database that belongs to my client and I'm sure he's not interested in moving his data to Azure. So I was wondering 2 scenarios:. Note: I know in Android i could use something like the Android sync framework In iOS i don't know how to handle syncbut I prefer to have 1 Xamarin Forms project for both platforms.

Arvindrajathanks for your answer. So this sync adapter is independent from the platform? As for as i know that is platform dependent, even i have searched but i didn't find about forms, have you gone through the above link i think there you may found sync adapter with xam.

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azure mobile services offline sync xamarin

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Mobile Database Bi-Directional Synchronization with a REST API

Hello, I need to implement offline functionality for a Xamarin Forms app, just retrieve the data from the server and push it into an sqllite database and then work with that data.

So I was wondering 2 scenarios: 1 Try to convince my client and use Azure only for sync purposes, Any suggestions or tips are welcome. Thank you. Tagged: azure forms sqllite sync. November Sign In or Register to comment. Facebook Twitter GitHub. About Xamarin Xamarin.


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