Vega headless JS : components, common integration challenges, tools and best practices

[Siddhesh_Pandit]

This blog focuses on common integration challenges in headless JS environments with Vega and suggests strategies to overcome these.

But, before we dive into this, let’s understand the three fundamental component types in your Vega app and understand where headless JS approach fits in.

1. Interactive Components: these are dedicated to UI rendering and user interaction. These interact with service components.

2. Service Components: these can be background processes that allow interaction and data exchange. They are able to operate over a secondary JS runtime and help UI components use the main JS runtime and improve apps performance.

   • Media player implementation for streaming standards (MPEG DASH or HLS) can use significant system resources, especially when UI elements are run from the same thread resulting in poor user experience.

3. Task Components: “Fire and forget” background tasks without interaction capabilities, this component is a great candidate to be implemented via headless JS to reduce load on your apps main JS runtime.

   • The EPG (Electronic Program Guide) used for Live TV** is a good example, as the Sync task represents crucial background activities as listed below :
     • Performs 24-hour periodic updates of channel and entitlement data in the background. The time interval for repeating EPG sync task can be defined by your app via using Epg Sync Scheduler APIs. The schedule interval has a range of 5 through 1440 minutes.
     • Includes built-in retry mechanisms for failure handling if task fails with Promise.reject(error) for any reason, the system will automatically retry up to 8 times with an exponential backoff, more on EPG error handling here.

Common Integration Challenges during headless JS implementation in Vega
While attempting to isolate the service or task components to headless js, the two common problems you might run into while attempting compilation are as listed below :

1. Import related issues

   • Use of broad imports from React Native libraries.
   • Incorrect importing patterns lead to inclusion of unsupported modules.
   • Transitive dependencies often bring in unexpected UI components.

2. Bundle generation problems

   • File extension sensitivity (.js required, not .ts) in case of headless services and tasks.
   • Missing task.Hermes.bundle or service.Hermes.bundle files

Tools and best practices to overcome the above challenges are listed as follows:

Headless JS Bundle Validator
To address import related issues, use the headless js bundle validator tool. This tool will list modules that are not supported in the headless JS context and trace the origin of those modules in their headless JS task or service bundles.

As seen above, It will also help with the following.

• Generate dependency graphs for troubleshooting.
• Helps developers trace problematic import chains.
• Verify bundle presence in packages.

Download validator.zip (77.4 MB)
The zip file contains a readme that explains installation steps, the tool and a video walkthrough of the expected usage.

Live TV validator tool **
This tool which is available via Vega Developer Tools performs high-level checks on a Live TV** Package or Manifest file to validate that the necessary integrations have been completed.

• Validates manifest.toml entries.
• Checks for required bundle files.
• Verifies integration completeness.
• Performs high-level package validation.

While the above tools are meant to help you troubleshoot, there are some best practices and recommendations that should be considered during implementation.

Import Management

• Use deep imports instead of broad package imports.
• Implement headless-specific exports for shared code.
• Avoid importing full React Native libraries in headless context.

Code Organization

• Separate UI and headless code appropriately.
• Create dedicated headless exports for shared functionality.
• Implement proper error handling and retry logic.

As you embark on your journey to leverage the benefits of headless JS in your Vega apps, remember that with the right tools and best practices, the integration challenges can be effectively overcome and you'll be well on your way to delivering high-performing, resilient headless experiences for your users.

All the very best!

**Important: At this time, these feature integrations are available to select partners only.