While Packaged Apps are the recommended way to deliver your Firefox Marketplace apps, there may be benefits to using the Hosted App approach. This page provides a guide to the key differences between these delivery methods and offers advice on choosing between the two.
The primary difference between Packaged Apps and Hosted Apps is fairly obvious: the former delivers all its content onto a user’s device, while the latter delivers the app‘s assets on demand from a web server. However, there are many more subtle differences that you should consider when choosing between the two.
Packaged and Hosted apps compared
Let’s start by looking at key features of Packaged Apps and Hosted Apps and see how they differ.
Functionality
The overriding reason for creating a Packaged App is the functionality it can offer to your users. Packaged Apps can use the Privileged APIs, which provide apps with the ability to integrate closely with hardware and software features on a Firefox OS device. If, for example, your app wanted to allow the user to select and use details of contacts stored on the device, this can only be done in a Packaged App.
| Feature | Packaged Apps | Hosted Apps |
|---|---|---|
| API support | All available Firefox OS APIs | No access to Privileged and Internal (Certified) APIs |
| Device integration | Excellent (see API support) | Limited |
| Can access web resources | Yes | Yes |
| In-app purchases | Yes (but requires own server too) | Yes |
Performance
In general you should expect users to observe better response from Packaged Apps, as all the app’s assets are stored locally on their device. When accessing remote data from the Internet, generally there’ll be no significant difference between the two options.
| Feature | Packaged Apps | Hosted Apps |
|---|---|---|
| Start-up time | Fast, all assets on the device | Network limited, all assets downloaded |
| Network impact | Remote data only | App content (unless AppCached) and remote data |
| Content optimization, e.g. screen size | Through redundant assets or multiple packages | On-the-fly |
| Impact of data plan limits | Low | High |
Availability
While Firefox OS supports AppCache and local data storage, Packaged Apps provide the app’s assets locally by default, removing the need to explicitly design for application caching.
| Feature | Packaged Apps | Hosted Apps |
|---|---|---|
| Offline support | By default for packaged assets, support for online data needs to be specifically added. | Needs to be specifically added for all app resources. |
| Availability constraints | Device battery and network availability (if applicable) | Server uptime, device battery and network availability (if applicable) |
| Supported on Android | Yes (APIs limited) | Yes (APIs limited) |
| Supported on Desktops | Yes (APIs limited) | Yes (APIs limited) |
| Runs on any browser | No, Firefox specific | Yes, unless Firefox specific APIs used |
Hosting
The cost and effort of hosting a server to deliver Hosted Apps may be an issue for you, if it is then Packaged Apps have a clear advantage.
| Feature | Packaged Apps | Hosted Apps |
|---|---|---|
| Server required | No | Yes |
Discovery
In most cases you’ll want your web app to be easily discoverable by user’s worldwide. For most apps you’ll achieve this through the Firefox Marketplace, however, Hosted Apps offer some additional possibilities.
| Feature | Packaged Apps | Hosted Apps |
|---|---|---|
| Discovery | Through Marketplace | Through Marketplace and own site |
| Direct access using a URL | No | Yes |
Delivery
All apps need to be delivered to a user’s device, which will be affected by both the network bandwidth and the available storage memory on the device. Here the overall size of your app’s assets will be the primary decision driver, the larger your app the more likely you’ll want to deliver it as a Hosted App.
| Feature | Packaged Apps | Hosted Apps |
|---|---|---|
| Marketplace review time | Longer (when using Privileged APIs) | Shorter |
| Self-publication | Yes | Yes |
| App updates | Requires a new package to be loaded onto Marketplace | Core app changes delivered on-the-fly, new install details (e.g. name, icon) require a new Marketplace package |
| App Asset/Content redundancy on device | Possible | No, only used assets/content downloaded |
| App asset limits | Practical package size limit is device memory and network dependent, generally < 50Mb, <5Mb for low memory devices | Online: No practical limit AppCached: As for Packaged Apps |
| Number of apps per device | Limited by device memory | Online: Practically unlimited AppCached: As for Packaged Apps |
| Asset extendibility | Limited, except for data from XMLHttpRequest and browser links all assets must be on the device | Unlimited, within Origin |
| Remote content | By using iframes, but that content will not have access to privileged APIs nor will it have the default CSP applied to it. | By default |
Development
While there are no significant development issues to consider in choosing between Packaged Apps and Hosted apps there are some differences, which if nothing else, are helpful to be aware of before you start coding.
| Feature | Packaged Apps | Hosted Apps |
|---|---|---|
| Delivery standard | Proprietary (albeit a simple ZIP) | Web standard |
| Debugging | Easier, no Origin limitations | Harder for older versions; Firefox OS older than 2.1 and Firefox Desktop/Android older than 34 have a limit of one app per Origin |
| Reading JavaScript assets | Requires use of XMLHttpRequest |
Direct |
| Coding challenges | OAuth functionality for Facebook, Dropbox, Twitter, etc. | |
| Manifest must specify a launch_path | Required | Optional |
| Apps per Origin | Doesn’t apply | Doesn't apply; one for Firefox OS before 2.1 and Firefox Desktop/Android before 34. |
| CSP | Enforced | Optional |
| mozApps API install function | Apps.installPackage |
apps.install |
Making your choice
The choice of Packaged App or Hosted App isn’t necessarily a simple one. There are however a few key factors that can be used to determine the option to use, as shown in this flowchart :
To further assist you, here are some examples:
- A small offline game, such as tic-tac-toe, is well suited to a Packaged App.
- A large online game would be better suited to a Hosted App.
- An app that needs to provide alarms to the user would need to be a Packaged App, as Privileged APIs will be used.