Key Points That You Should Know About Offline Apps

These days, most of the users expect apps to work even when they’re offline. Else, bad network connection translates into poor user experience. Near about 21% users uninstalls an app just after one use. In app messaging, Push notifications and offline mode helps to retain users. Offline mode is necessary for delivery apps having GPS navigation, banking apps and apps for urgent medical assistance. Users like offline apps because it can work constantly without delays, can load immediately, and consume less battery. 

Types Of Offline Apps-

Based on the nature and function of app, offline apps are divided into 3 categories-

• One user can edit other user’s data- making edits to an offline Google doc type app.
• Data can be edited and synched offline, for example, note taking app.
• Data stored offline- without any editing functionality, eg., On-demand Uber – X app

Selecting An Architecture To Create Offline App-

While selecting the architecture for your offline, consider the following points- 

• Why is it important to know how and where to cache the data?
• What is the reliability of caching?
• How to handle concurrency?
• Which safeguards are in place to handle data conflicts?
• How is this architecture going to handle connectivity changes?

Types Of Offline- First App Architecture-

The data storage, sync and access may change according to the device, server and architecture. Some of the best development approaches are as follows-

• Caching- Data caching on local browser/server is simplest approach to help users with data reading in offline mode. This offers access to data on a device, renders the UI, providing a predictable user experience within a short time.
• Manual Replication- With this users can edit the data in offline mode by marking changes in objects. All changed objects are sent by push and pull operation once the network connectivity recovers.
• Real Time Data Sync By Platform– In this case data synchronization is automatic. Changes are send between device and server in minor binary format. Only some particular operations with data are synchronized, capturing the information intended by user, permitting the system to automatically resolve any conflicts, This focuses on performance because there is no manual intervention.

Selection Of The App Types Based on Offline Mobile App Architecture-

One should look for quick data retrieval upon multiple requests, complete offline capabilities and no reliance on the UI while selecting the architecture of offline-first application. On-demand type offline architecture are good for e-commerce apps, news apps, real time apps, map apps etc. Offline architectures are suitable for notes taking apps, weather apps, email apps, finance type apps, messaging apps.

How To Decide Offline Features For Your App?

Each mobile app is designed and developed based on the budget, business requirements, scope of application, availability of technologies and skills of developers on board. By considering all these factors, mobile apps are designed and developed. A way to handle errors might be different. Users can perform some of the actions while the app si in offline mode and then able to synchronize it as the app regains network connectivity. With some mobile apps, there are client-side and server side storage and app can manage data flow between server and client. Points that can help while developing offline mobile app- 

• Decide business needs, assess workflow, and translate it into app features.
• Give these features a priority as once they become significant for your business, they become urgent.
• Figure out what you need to achieve through your application and share this data with your developers. Help them to understand business objects and recommend precise technologies for custom solutions.

What To Consider While Selecting Technologies For Offline Mode?

Selection of technology will have a big impact on app’s offline mode performance.  So, consider the following points while selecting technology-

1.  Data synch-

Frequent reconnecting drains a mobile’s battery. But if app doesn’t synch frequently, users might miss necessary updates. So to balance it, work with development team. You have to check how frequently users can use high-speed internet. If your users use app for work, then decide which slots are good for downloading data in their work schedules. If data connections is good, those slots can be shorter.

2. Data Synchronization-

You should prioritize data as per business requirements. Some of the data needs should be updated once a year, while others need to be updated a few time a day. Decide various synchronization cycles for various data according to the business needs. Data packages that are smaller need high-frequency updates. If your app needs continuous data synchronization, you can sync data at a specific time. 

3. Sensitive Data Management-

Users sensitive data cannot be erased for security reasons. Downloaded data such as logos and blog posts are stored in a cache folder on the user device, so it doesn’t need to be downloaded each time the user uses that content. Cached info can be viewed by using back button of browser or checking the browser’s cache and this can show sensitive data such as usernames, credit card details etc. So, you must ensure that the sensitive data is not cached. 

4. Managing Shared Data Changes-

Sometimes, users are not online, data changes cannot be accessible to others. In this way, numerous clients may work on similar information without checking how others have changed it. If you can’t ignore this case, manage and decide rules to handle those exceptions.

5. Synch Ways-

To select the appropriate technologies for your offline mode, check whether data transfer should be synchronous or asynchronous, regardless of whether data will be synced manually or automatically, whether the application will ask the server actively for updates or the server will send new data itself to the application.

Implementing Offline Mode For Web And Mobile-

There are some differences while applying offline mode for mobile and web. Let us see how to store and synchronize data for mobile apps and web apps. Web applications store data in browser whereas mobile apps store them locally. ServiceWorkers and IndexedDB are tools to store data in the browser. 

1. IndexedDB-

This tool offers a better API than local storage API to store data in a browser. You can use IndexedDB or similar alternative for offline data storage. App shouldn’t make any HTTP calls so as not to fail in offline cases. In low-storage cases, browsers may clear IndexedDB. One can use persistent storage API to solve this problem.

2. ServiceWorkers-

ServiceWorkers operate as client-side proxies and can intercept client requests. It has a well-determined lifecycle. Google’s libraries sw-precache and sw-toolbox are used for caching static and dynamic content. 

Data Sync For Web And Mobile Apps-

Offline Sync For A Mobile App-

By the use of offline app, users can take actions offline and then synchronize changes with the central repository. For this, app should manage data flow between server and client. Most of the time, offline mode is used when users can edit data on the server side and on the mobile side. Despite the fact that it may be fascinating to create offline applications supporting two-way sync, it’s the most complicated method. If supports two-way sync, synchronization logic has to check that data is updated on the mobile and server side too. Data storage methods to make an app work offline differ for iOS and android.

Android-

SharedPreferences APIs of android platform can be used to save a small amount of primitive data in key-value pairs. SharedPreferences object is a reference to a file with key-value pairs. While using this, you have a key and value, the value can be boolean, float, int, long or string. Android stores SharedPreferences files as XML files in a private directory. One of the Method of receiving SharedPreferences object is used if an app contains a single preferences file and the other is used if an app contains more than one preferences file or if you want to give a custom name for the  SharedPreferences instance.

iOS- 

While implementing offline mode for ios app, you can make use of a NSUserDefaults class to save and update users’ preferences. This class delivers a programmable interface to customize its behavior based on the user’s preferences. You can allow users to save profile pictures offline or add a function which automatically saves documents. App records preferences in the user defaults system, and so helps you to avoid opening the user defaults database when you want a default value. When app is closed by user, they can still use the saved information the next time they enter the app.

Offline Sync For A Web App-

While storing offline data in a browser, you need to upload it to the server when the network is available. To ensure data syncs properly-

• Analyze the smallest amount of data to store locally.
• Select as less data as possible to transfer from server to device
• Configure conflict resolution
• Determine and prioritize data sets for syncing
• Balance synch frequency and battery drain
• Explain retry mechanism
• Send a sync status notification to users