We frequently receive questions about why the sync process stops when the user receives a phone call, switches to another app, or minimizes the Pulsar app. The reason is that the Pulsar app must comply with the operating system’s rules. Below is an explanation of how operating systems limit background tasks for applications when they're not in the foreground.

iOS, Android and Windows operating systems restrict background tasks for applications primarily to optimize battery usage, improve performance, and enhance user experience. While these operating systems offer ways to perform background tasks, these actions are constrained for several reasons:

1. Battery Life Concerns

Continuous background tasks can drain battery life quickly. Allowing apps to run freely in the background can lead to excessive power consumption, especially for tasks like fetching data, playing music, or location tracking. OS restrictions are designed to limit background activity and thus help preserve battery life, ensuring that the device performs well throughout the day.

2. Resource Management

The operating systems are designed to prioritize system resources (CPU, memory, and bandwidth). Running multiple tasks in the background for several apps can cause performance slowdowns. To prevent this, the platforms limit background tasks unless necessary (e.g., for notifications, system updates, etc.).

3. User Control and Privacy and Security

User control and transparency are crucial aspects for these platforms. Apps shouldn't be allowed to perform tasks in the background without the user's awareness or consent. Apps running in the background could potentially gather data, track user activities, or perform other actions without the user's knowledge. Operating systems impose limitations to ensure privacy and security by restricting what apps can do in the background.

Platform-Specific Background Task Policies

• iOS:

  • iOS restricts background tasks unless they're explicitly supported. iOS provides a few specific use cases for background execution, such as background fetch, remote notifications, and background location services. But the system will suspend apps that use too much CPU or memory when not in the foreground.

  • Background Fetch: iOS allows apps to periodically fetch data in the background, but it’s not continuous—it's optimized based on the app's usage patterns.

  • Background Audio and VoIP: Apps like music players or VoIP services (e.g., WhatsApp, Skype) can run in the background to perform their tasks, but again, only within allowed constraints.

  • More information: https://developer.apple.com/documentation/backgroundtasks

• Android:

  • Android allows for more background tasks through Services and WorkManager. However, recent Android versions (especially from Android 8.0/Oreo onwards) have introduced limitations to restrict how apps can run background tasks.

  • For instance, Doze Mode and App Standby restrict background activities when the device is idle to save power.

  • Apps can still use JobScheduler and WorkManager to handle background tasks, but they are scheduled in a more optimized way to prevent excessive resource usage.

  • Background location tracking and push notifications are examples of allowed background tasks, though these too are heavily regulated.

  • More information: https://developer.android.com/guide/background

• Windows

  • Apps that are submitted to the Microsoft Store (formerly Windows Store) are subject to strict guidelines on how they can operate. The platform enforces certain rules to prevent apps from doing anything harmful to the system, such as using excessive resources in the background.

  • UWP apps have a more restrictive lifecycle compared to traditional desktop applications. When an app is not in the foreground, it is typically suspended by the operating system. This means that the app isn’t allowed to continue using resources unless explicitly granted permission to do so in the background.

  • When an app is suspended, it can no longer perform most background tasks unless it is using specific APIs like Background Tasks, Background Media Playback, or Push Notifications. These mechanisms let apps perform certain actions like downloading updates or processing data but are controlled by the system.

  • Windows does allow some types of background tasks, but they are managed by specific APIs. Apps can register background tasks (e.g., for periodic data sync or notifications), but they are restricted in how often and how long they can run. These background tasks have specific rules regarding what they can do, and their execution is closely monitored by the operating system to avoid misuse.

  • More information: https://learn.microsoft.com/en-us/windows/uwp/launch-resume/support-your-app-with-background-tasks

Conclusion:

Apps can perform some background tasks (e.g., fetching data, playing music, notifications, location tracking), but continuous and unrestricted background processing is generally not allowed due to battery life, system performance, privacy, and security concerns. Instead, both iOS and Android encourage developers to optimize tasks and only run background processes when absolutely necessary or based on specific system events (e.g., notifications, alarms).