---
title: 'Vaandroid Implementation Issues'
url: 'https://www.twelvetone.tv/docs/operating-systems/vaandroid/vaandroid-planning/vaandroid-development/vaandroid-implementation-issues'
markdown: 'https://www.twelvetone.tv/docs/operating-systems/vaandroid/vaandroid-planning/vaandroid-development/vaandroid-implementation-issues.md'
date: '2026-09-25'
description: 'A description of various implementation issues. Intent'
taxonomy:
  category:
    - docs
  devtype:
    - private
---

[](#)  [ Home ](https://www.twelvetone.tv/docs/)     [ Operating Systems ](https://www.twelvetone.tv/docs/operating-systems)     [ Vaandroid ](https://www.twelvetone.tv/docs/operating-systems/vaandroid)     [ Vaandroid Planning ](https://www.twelvetone.tv/docs/operating-systems/vaandroid/vaandroid-planning)     [ Vaandroid Development ](https://www.twelvetone.tv/docs/operating-systems/vaandroid/vaandroid-planning/vaandroid-development)      Vaandroid Implementation Issues    

# Vaandroid Implementation Issues

A description of various implementation issues.

# Intent Serialization

In Android, intents are used the messages between activities. The intents payload must be serializable, and this is a double edged sword.

This is good because the intent can be saved to disk or marshaled to another process.

This is bad because plain-old objects cannot be directly sent to or from an activity, service, etc.

# Activity Results From Fragments

Not possible (without ActivityHelper workaround) to start an activity from a fragment and get the result.

# Resource IDs

Resolving IDs

System IDs versus Plugin IDs

Menu item IDs from super class in another bundle

## ID References

There are 3 ways we can referer to an ID.

### Number

An ID specific to a scope.

resource://server/plugin/12

### Alias

A string that is used as an identifier

resource://server/plugin/photo

### Path

A path that referers to the location of a resource.

resource://server/plugin/images/photo.png

## Availability

In Vaandroid, resources referer to URLs that might be cached by the client. That means they are possibly available to a client even if the providing plugin is not available.

# Drawable

- Vector Resources 
    - When to convert to SVG
    - Cache SVG
- Client can cache
- Resources in ZIP files
- Caching on server
- Expiration Time 
    # Overriden API Methods

# Java 8

Streams and lambdas were not implemented until API-24.

# Menu Item State

Showing and enabling menu items based on the selection state of activity views.

# Android Studio

Pointing the source to either the Android API or the Vaandroid API.

Complaining about unsupported Java 8 Stream API

# WAB Bundle Build Issue

# WAB Bundle refresh Issue

# Multiple Tabs / Single Session

Shared session on browser creates issues. Application is per Vaadin UI, so we put a hash map in the session.

# Cycles In Bundles

seeing package not found: javax.microedition.khronos.egl when installing core means there is a cyclic dependency (e.g. an api package used in core and depending on core)

# Click Issues

In Vaadin, radio buttons do not get checkChanged or click events. All events go to the radio group. This creates a compatibility issue with Android. We need to extend Vaadin to get the Radio Button clicks.

# Background Refreshing

# Widgetset in plugins

# Resource Sharing

Making files and endpoints accessible from outside. Caching. Security issues.

# Conforming To Android API

# Moving Activities Between Browsers

## Client State

getClientState() and setClientState() need to be added to synchronize browser state. This needs to be asyncronous.

## JavaScripts and CSS

Web browser resources need to be installed on the target browser

# Browser Back / Escape

Integration of browser back and escape (closing popup windows, canceling prompts, and exiting from activities)

# Other Issues

Since beginning this project, we have encountered several issues.

- Zip File Already Opened
- Resource ID Delegation
- Android applications use integers to indicate resources. 
    - The resource IDs are defined as strings, and are converted to integers at compile time.
- An Android application can use an ID defined by the application, a library (also at compile time), or from the SDK.
- Android applications cannot ‘share’ or ‘export’ their resources at runtime.
- Vaandroid applications use integer IDs too, but the developer must specify if the ID should be resolved by the containing plugin, the parent plugin, or the system.
- Rebuilding the core requires rebuilding the plugins when the core ids change.
- UI Threading
- Feature Tracking
- Tracking what Android features have been Implemented and not Implemented.
- Dropped Database Connections
- Database Connection Leaks
- Bad Karaf Documentation

 [ ](https://www.twelvetone.tv/docs/operating-systems/vaandroid/vaandroid-planning/vaandroid-development/goals) [](https://www.twelvetone.tv/docs/operating-systems/vaandroid/vaandroid-planning/vaandroid-development/changes-issues-and-gripes)

---

## Navigation

- Parent: [Vaandroid Development](https://www.twelvetone.tv/docs/operating-systems/vaandroid/vaandroid-planning/vaandroid-development.md)
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