An Overview of Open Web Applications for Developers

By Scott Clark

You may have heard about Google's coming venture in web-based applications. The Google Chrome Store will soon debut as a marketplace where users can buy and download applications that will work on desktop browsers as well as mobile devices. Now Mozilla has announced it will be opening its own Open Web App Store where similar apps will be available. So just what are these web apps? They are applications that are made using the core technologies of the web: HTML, CSS and JavaScript.

These "web apps" will be available as both paid and free downloads, and at this point it looks like almost all web browsers will support them. They utilize a combination of both server-side and client-side logic, and are poised to take advantage of the popularity of mobile devices as well as more traditional desktop-based web browsers.

How Does a Mobile App Work?

Both the Google Chrome Store and the Mozilla Open Web App Store work the same way. A user looks through an app directory, selects, pays for, and downloads an app (or if the app is free, selects and downloads it), and receives the application in a "dashboard" of sorts in their web browser. When the user launches the app from that dashboard, the app verifies the ownership of the app instantly, and the app starts up.

The Google Chrome Store

The Chrome Store, when it opens, will work essentially the same way as all app stores. Users locate, purchase, download, install and use. The method used to verify ownership is through the use of a special file, called a .crx file--created by the Chrome Web Store--that is signed and contains an auto-update URL. When the user downloads a .crx file that is created by the store for a particular app, the app will only be installed if the .crx file is coming from the Chrome Web Store. If someone tries to use a .crx file they downloaded from a .torrent site, for instance, they will not be able to be installed on their browser.

If a developer wants to sell apps from the Chrome Store, they must open a merchant account with Google Checkout, and associate that account with the store. When someone buys their app and uses Chrome Web Store Payments, Google charges them a processing fee of 5% plus a transaction fee of $.30 cents.

The Mozilla Open Web App Store

In the case of the Mozilla Open Web App Store, the application itself lives in the local storage of the user's web browser, whether that browser is on a mobile device or a desktop. The app uses the functionality of HTML 5 and a JavaScript library that uses the HTML 5 postMessage API to securely talk between the app and the app store's domain.

It sounds simple, however Mozilla offers several models for developers: self-published, free and registered apps. For self-published apps, the App Store repository prompts the user for confirmation, and once done, it adds the app to the user's dashboard, and if the app needs additional permissions, they are confirmed before the app is installed.

Registered apps create a user identity for the application, which enables a single-sign on experience for that user. An authorizationURL is saved, and the app can continue to request the user identity/verification data, and once verified, an identity token is provided.

Web Apps Are the Future

The creation of the Mozilla Open Web App Store and the Google Chrome Store provide a glimpse of the future. Web apps that are created using HTML5, CSS3 and JavaScript, that can be used by practically every web browser out there, are the goal of every web developer. Apps that require proprietary software are the subject of many heated discussions, and the Apple vs. Adobe debate will likely continue to gain momentum, but the verdict is almost decided in the community. Open web applications are likely to continue to gain acceptance by end users, and for developers, they are a way to monetize the knowledge that they already have.

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