The Basics to Making your Web Application Work Offline

November 24, 2021

The number of web applications has increased tremendously in the recent past. These applications require internet connectivity, which partly explains why there is a growing demand for internet services to gain access to them. However, in the event of a lost internet connection, users find it difficult to gain access to online applications.

This is especially the case for applications that support online mode only. Lost internet connection may be caused by poor internet coverage, poor weather conditions, and power outages. There is a growing need for applications that allow usage even in the event of poor internet or lost internet connection.

This article takes you through the basics of making web applications work offline. It will also go through the benefits of having an application that supports offline mode and implementing this functionality.

Offline mode explained

Offline mode is a functionality that enables web applications to operate when there is no internet connection. If the web application is in online mode and the internet gets disconnected, some of the functionalities of the application will still work.

The user can still view the images that have been loaded on the web page and compose messages (in the case of social applications). However, this functionality may not be available if the application supports online mode only.

Although there is a significant growth in access to internet services, it is inevitable to experience instances of lost internet connection. If an application has no offline mode, users may experience inconveniences in the event of internet disconnection. Developers are working hard to incorporate both online and offline modes in web applications to improve the user experience.

Benefits of having an application that works offline

Having an application that works offline can lead to the following benefits:

  • Uninterrupted usage: Users can continue using applications that support offline mode even in the event of a power outage or lost internet connection.
  • Competitive advantage: Making your application work offline can give your business a competitive advantage over other firms. This is because your application provides superior features to other applications that do not allow offline mode.
  • Customer loyalty: Offline mode improves user experience and enhances customer satisfaction. When an application does not have an offline mode, customers may be frustrated because they cannot access the application in the absence of an internet connection. This may make them seek other alternatives.
  • Improved performance: Offline mode applications are forms of progressive web applications that enhance better performance than traditional applications. This is mainly in terms of loading speed. Offline mode applications load faster than traditional applications.
  • Increased revenue: Commercial web applications that have offline mode make customers spend a lot of time on the web pages, which contributes towards increased conversion in the long run.

Deciding offline features for your application

When building an application that supports offline mode, it is important to choose features that will work offline. This is because not all features may be necessary for offline mode. Before selecting these features, the management should establish the main objectives of the application. This will ensure that the selected features meet these objectives.

The selection of offline features may be done by order of priority. The management can select features that the business cannot do without. Some features may be important to some users more than others. Understanding the importance of features to users may require interacting with them to get their point of views.

After establishing the features that are needed for offline mode, you should evaluate the time and resources that may be required to implement them. A cost-benefit analysis can help in ascertaining whether the efforts made to implement the selected offline features are worth it. Only feasible and important features should be selected to avoid wastage of resources.

Choosing offline mode technologies

The following are the considerations that should be made when choosing technologies for your offline web applications:

  • Data synchronization frequency: Developers should strike a balance to ensure that data synchronization is neither too often nor too seldom. Frequent synchronization may consume the user’s phone battery while rare synchronization may make users lose important updates.
  • Synchronization time: This depends on the nature and needs of the business. Some updates may be done daily while others may be done annually depending on the type of data. Daily updates are suitable in the case of small data packages. It is ideal to have a specific time for synchronizing data.
  • Sensitive data: Developers should consider how sensitive data is handled to avoid security concerns. When using offline mode, a cache folder is used to store downloaded information. You should ensure that sensitive information such as usernames and bank details are not cached.
  • Syncing method: You should choose an appropriate technology when syncing data. In this case, you can choose whether to allow data to be synced manually or automatically.

Implementing offline mode

The implementation of offline mode in web applications depends on the following operations:

  • Offline data storage
  • Data synchronization

Offline data storage

When building a web application that supports offline mode, data is stored in the browser.

The following are the main data storage tools employed:

  • IndexedDB: This is also termed as Indexed Database API. It is used when making data available to the client-side of the application in offline mode. Your application should not allow HTTPS calls to avoid failure in offline mode.
  • Service workers: These tools work as proxies for the client-side of applications. When clients make network requests, Service workers intercept them and send responses to the clients.

Offline mode does not depend on networks. In this mode, downloaded data is stored in an offline cache. Service workers fetch cached responses from the offline cache and send them to the clients.

The following diagram shows the lifecycle of the service workers.

Service Workers

Image Source

Data sync for the applications

When the user is in offline mode due to a lost internet connection, he can still perform some actions. The IndexedDB stores these user actions. The corresponding data is synchronized with the server when the network connection resumes so that any pending jobs can be processed. It is important to set the triggers of data synchronization. The developers should set a reasonable sync frequency that optimizes battery usage.

Conclusion

In this article, we have gone through the basics of making your web application work offline. To summarize:

  1. We got an overview of what offline mode is.
  2. We have learned the main benefits of having a web application that supports offline mode.
  3. We have gone through the main issues that should be considered when choosing offline mode technologies.
  4. We have looked at how offline mode is implemented in web applications.
  5. We have gone through the main data storage tools when an application works offline.

Happy learning!


Peer Review Contributions by: Onesmus Mbaabu


About the author

Arthur Muthee

Arthur is a Kenyatta University graduate student who is passionate about technologies that automate and improve the use of financial services. His interests are cryptocurrency, mobile development, and Big Data. His hobbies are socializing and traveling.

This article was contributed by a student member of Section's Engineering Education Program. Please report any errors or innaccuracies to enged@section.io.