Basics to Make Your Mobile App Available in Offline Mode

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Irrespective of the developer’s skills, availability of your servers and the continuity of the internet – there are times every development team requires to support their apps offline. This blog discusses the use of offline mobile app architectures to develop robust apps that tackle offline capabilities most efficiently.

How Do Most Apps Work?

Most applications make use of a simple cycle of data transfer including the app on one side and the content from a server on the other side.

The backend database must be able to interact with the frontend content to ensure a smooth transfer of data anytime it’s needed.

Factors that Define Customer Experience

Two factors play a major role in defining the right customer experience here:

• The network connectivity
• The underlying customer experience for failure rates depends on how the given application deals with being offline.

What is the need to have apps in offline mode?

Smartphones, powered by the internet are good to be used at convenient locations, at convenient times. Most importantly users feel like using such service – to check if it works, to see how technology creates wonders, to ease themselves from the burden of physically travelling to the location to get the things done, to have it as a helping hand when no one else is around to help them. There has been an increase in the purchase of goods and services using smartphones, either through native or web applications. Considering all other factors, the facts remain that mobile networks cannot be relied on. There are areas with high, medium or very little coverage and even no coverage at all. Besides, there are emergencies when cellular services are barred. The modern mobile applications have to be well-equipped to encounter such high latencies and network failure rates.

Types of Offline Apps

Depending upon the nature and function of the app, these can be divided into three broad categories:

• Data stored offline – without any editing functionality. E.g.: On-demand Uber – X app.

• Data can be edited offline but can be synched offline. E.g.: A note-taking app.

• One user can edit other user’s data – making edits to an offline Google doc type app.

What advantages do apps in offline mode for an iOS App or Android App brings?

• No roaming cost when you are traveling
• No monthly data usage on maps
• Quick loading time
• Saves your battery

Principle: Make an App Work Offline

Developers design certain error states to make their apps work smoothly even in case of no network/intermittent network or complete loss of connectivity. The best error state is the one that never shows up. Every developer codes in a way to minimize the frequency of errors. Test teams check the quality of the code with all their might. While it is always better to avoid the errors to occur in the first place by guiding users in the right direction ahead of time. But in case they do arise, despite the smoke test or user acceptance test, it is only a well-designed error handling that can pull the mobile app from receding. Acquainting users the basics of handling the app properly and preventing them from feeling ignorant can be other ways of handling such situations.

The offline applications are the ones that automatically deal with network failures. They function in a particular way by creating unique transaction identifiers that allow the back-end to detect duplicated transactions, enabling the application to automatically try reposting the transaction after a failure. The backend of the offline application supports a polling mechanism that allows the client application to inquire about the state of the transaction. The responsiveness of the application allows the customer to be informed of the intermediate states of the transaction, such as when an item has been added to cart, the cart value does not change in case of intermittent network connectivity, when the payment has been authorized and when the reservations have all been confirmed, etc.

Such applications are resilient to most of the client-side failures. All the transactions continue correctly even if the users close the tabs, or if the browser crashes or the device shuts down. All pending transactions are resumed from where the customer leaves, updating itself with the most recent transaction status.

How does a mobile application handle the “No Connectivity” state?

Normal mobile applications must handle extreme ends of quality spectrums in the following ways:

• When a network error occurs, the app must present the user with a relevant error message.

• The application must automatically deal with network failures

• The application must be able to provide some cache data so that the “cart value” in the case of e-commerce application is not lost in between.

• The transaction must continue correctly even if the user closes the tab, refreshes the page, gets stuck due to slag in the network, gets stuck due to delay in response via chosen payment gateway, the browser crashes or the device shuts down.

• The application must resume from where the customer leaves.

All these are the good end of the spectrum. Perhaps they cater to some unique transaction identifiers that allow the back-end to detect transactions that are duplicated, allowing the application to automatically try reposting the same error message in times of failure.

The mobile application must be responsive enough and notify customers about the intermediate states of the transaction. Such applications are also resilient to some client-side failures.

Selecting an Architecture to Create Offline App

Points to be considered while selecting an architecture for your offline app:

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

Types of Offline-First App Architecture

The app always assumes data to be local. The storage of data, sync, and access may vary according to the device, server, and architecture. Here are some of the best development approaches:

• Caching – Caching data on the local browser/server is the easiest approach helping users with handy data for reading in offline mode. This gives access to data on a device, renders the UI, providing a predictable user experience in a short period.
  

• Manual Replication – It allows users to edit the data in offline mode by marking the changes in the object. All changed objects are sent by the push and pull operation when network connectivity recovers.

• Real-time Data Sync by Platform – Data sync is not manual but automatic in this case. Changes are sent in minor binary format between the device and server. Only some specific operations with data are synchronized, capturing the information intended by the user, allowing the system to automatically resolve any conflicts. This accentuates performance as there is no manual intervention.

Image Source: https://academy.realm.io/posts/three-approaches-offline-first-development/

Selection of the App Types Based on Offline Mobile App Architecture

One must look for fast data retrieval upon multiple requests, complete offline capabilities and no dependency on the UI while making a selection for the architecture of an offline-first app.

On-demand type offline architectures are suitable for e-commerce apps, real-time apps, news apps, map apps. The reason being the faster data retrieval and handling connectivity efficiently. But this is not true offline functionality.

Ahead of time type, offline architectures are suitable for Notes taking apps, Email apps, Weather apps, Finance type apps, Messaging apps.

How to decide on offline features for your app?

Every mobile app is designed and developed according to the budget, demand of the business, the scope of the application, the available technologies and the skills of the developers on the board. Considering all these factors, not all mobile applications are designed and developed keeping one requirement in mind. The way to handle errors may be different. Users can perform some actions while the app is in offline mode and then able to synchronize it as the app regains network connectivity (synchronize it with a central repository). In most mobile applications, there are client-side and server-side storage and the app can manage the flow of data between server and client.

Some points that may help while creating a mobile app that works in offline mode as well:

• Analyzing the workflow, determining the business needs and processing all the gathered information into app features.

• Prioritizing the most relevant features of the business according to the scope of the application and the basic motto of developing that particular app.

• Sharing all the gathered information with development and test teams and decide upon the features of the app that could be made available while it is in offline mode

Making App Offline-First

The concept to make a mobile app work offline in the same way it does while in online mode with complete network connectivity is called Offline First. It is a way to build a mobile application so they may work in the absence of network connectivity. Later is an enhancement and not a necessity.

The Client-Browser Stores Local Data

• The application has stored the data locally to display it in offline mode.

• Technologies like SQLite, PouchDB, CouchDB, Cloudant, Node.JS exist that work on the client-side.

• The client has its dedicated database, which is then replicated to a dedicated database on the back-end.

• Each database has customer documents (which are JSON files/objects that may contain any arbitrary data).

• CouchDB and variants act well in the case of one database per user.

• It’s also a way to clearly and naturally separate and enforce the accessible data to the user.

• The sync protocol replicates the changes on the other side. The network connection isn’t possible in case a client tries connecting the second time.

• Both databases can communicate and synchronize with each other.

• Both client and server-sides are allowed to make changes to the data concurrently.

• The replication protocol ensures that both databases converge to the same version of that document in case of a conflict.

• Pouch and CouchDB keep all the conflicts away.

• Programmers can resolve that conflict with any strategy they deem correct and that minimizes data loss.

• In addition to the ability to sync, PouchDB (and CouchDB) is capable of keeping the entire revision history for any document.

• Providing asynchronous changes feed that can stream different versions of all the documents. This transforms PouchDB (or CouchDB) into an event queue to be processed by a clerk process. This clerk can then process document changes and interact with back-end services at will.

• The clerk worker (implemented in any language runtime) can make changes to any given document which eventually gets propagated into the client application by the sync protocol.

• js has an open-source pouch-clerk library that can simply use the library and easily roll out on its own.

• Each transaction can then be described by one document on the customer database. This document has all the necessary information (included all the states of a transaction) to perform the next step for subsequent transactions.

Building an Offline Storage in Android and iOS

The Android Platform makes use of SharedPreferences API’s that are there for securing small chunks of primitive data (in pairs). It refers to a file with key-value pairs (Boolean, float, int, long, string). Android stores these files in XML format in a private directory. An app can have such shared preferences files, local (internal and external storage) for storing pictures, audio, video files, serialized objects, XML, JSON objects and other files. Android app has methods to receive such objects (single preference file and more than one preference file)

The iOS Platform makes use of NUserDefaults Class to save, update and sync offline users’ preferences. The aforementioned class delivers a programmable interface, thus allowing the mobile app to customize its behavior according to a user’s choice.

This works in this way: A user saves a profile picture offline or adds a function that automatically saves documents. The app records such preferences in the users’ default system, the data gets cached. As this default system is available within your app’s code, any data saved to it will persist across app sessions. As the user closes the app and resets or reboots the smartphone device, they still can make use of the saved information the next time they enter the app.

What is an Offline Mobile Form?

Features:

• No internet connection required.
• Faster Data Collection.
• Real-Time Analytics
• Removes Paperwork.

What it is:

Offline mobile forms are designed to be used in offline mode in smartphones. A mobile app can allow a user to access features in the absence of network connectivity. It goes by collecting all the data input by the users and stores it in the smartphone device until the network connectivity is restored. It simultaneously saves a lot of paperwork for businesses along with aligned time and efforts.

Advantages:

• Saving a lot of buffer time.
• Collection of mass data with ease.
• Remote area accessibility.
• It is a cost-effective and accessible option for all industry domains.
• It reduces the hassles of making use of paper forms substantially.
• This method completely eradicates the onset of human-induced error.
• Helpful in checking competitors’ activities and making improved business decisions.

High-Level Tools & Frameworks for Offline-First Apps

• Progressive Web Apps – the power of native mobile apps with the web.

• Polymer App Toolbox – a collection of components, tools, and templates for building Progressive Web Apps with Polymer.

• Hoodie – a complete backend for your apps: develop your frontend code, plug it into our API and your app is ready.

• Ionic – Ionic is a tool that allows you to create hybrid mobile apps using Angular.

• Couchbase Mobile – Couchbase Mobile is a set of tools that can be used to take an offline-first approach to your data.

• Realm Mobile Platform – allows you to take an offline-first approach to your data by enabling real-time data sync between a Realm Mobile Database embedded in an iOS or Android app and the Realm Object Server.

• Mapbox Mobile – is an open-source SDK lets developers add beautiful maps and turn-by-turn navigation to their apps that can go offline. Maps do not need a data connection. Both ios and Android SDKs can pre-cache maps to save bandwidth and data charges, optimize performance and anticipate the lack of network access.

Low-Level Tools & Frameworks for Offline-First Apps

Service Workers – Similar to HTML5 Application Cache (AppCache) that provides a browser mechanism for caching content and assets for offline usage, it gives fine-grained control over caching content and assets for offline usage by intercepting client requests and returning previously-stored results when offline. localForage – IndexedDB, WebSQL, or localStorage are some real-time natural database options that work in coordination with the local Forage wrapper class providing a unified API. PouchDB, Cloudant Sync, Cloudant Envoy – are some examples of low-level tools that propagate offline-first apps.

Advantages of Creating Offline Mode for your App

Users appreciate apps that work offline due to the following reasons:

• A mobile app that works well in offline mode is particularly helpful to businessmen and working professionals who have to frequently commute to their work locations.
• For those who spend significant time in subway tunnels or travelers during the national or international commute.
• Poor connectivity isn’t a hurdle in customer experience with offline apps.
• You will have an edge on the competition
• Gain more loyalty from the users
• Users want an app that works instantly and without any delays or difficulties.
• Users can make changes to their data, regardless of an internet connection.
• When stored locally, the data has little to no chance of getting breached.
• Such apps require very little loading time.
• The battery drain is less.

Examples of Offline-First Implementation

Offline apps make lives easier naturally, make work more productive and time-efficient. Apps have to be offline-first so that they do not slow down when connectivity is poor.

1. In case of purchasing a plane or a bus trip, it should contain all the flights, passenger data and payment methods and other required details.

2. In the case of e-commerce shopping portal (Merchant-managed e-commerce implementations and Shared-management e-commerce implementations): It contains all the products with respective quantities and the payment method identifier.

3. In the case of a Taxi application, the various states can be modeled (request for the driver, search driver, assigning driver, on the way driver, the arrival of driver, picked up, in transit, etc.). All the long-run transactions can be modeled in this way, making the transaction document slowly transitions state.

More examples include Ecommerce Apps, Photo editing apps, Netflix – Live Movie and Video Streaming App, Google Maps, Trello’s, Robospice, Retrofit, etc.

Besides the advantages and disadvantages of an eCommerce application accessible in offline mode will essentially depend upon one or more of these: (1) iframes, (2) JavaScript forms, (3) APIs, (4) URL Direct, (5) Direct Post.

Need: Why you should create an offline mobile app for Android and iOS

Networks can be crappy, intermittent and low with battery constraints and a lot of other factors that would put a mobile application to test, most often needing offline support. Your business would be accountable in case you have a global audience. Offline web app support is required irrespective of the server availability, skills of the developers or the device support

Poor network connectivity is directly proportional to poor user experience. It leads to frustration and turning the users off. Creating a mobile app on the better side of the spectrum, one that can also be made available offline would be a competitive advantage, requiring some initial investment on the back-end and front-end development. It is best to select a native app over a responsive website while catering to a global audience. This can help leverage device storage capability allowing for offline access. We have development teams that look effortless but their efforts take hold as they code. Grab the chance to have the best development team on board and rim your business to create offline apps that are inspirational and feature-rich. Get a quote here!