What are mobile web frameworks

What are web based application frameworks? First, there are many out there including PhoneGap, Appcelerator, etc. For developers struggling to learn Objective-C, Java, etc these frameworks allow you to still build mobile applications. Essentially, these frameworks exist to help developers that come from a web development background with a set of tools to use with their current skillset (HTML, CSS and Javascript) to build native or native-like mobile applications. PhoneGap and Appcelerator Titanium are the most popular amongst all the frameworks out there on the interweb. For this blog post, I want to compare and contrast the two along with other mobile frameworks. Hopefully this will help you if you’re deciding on which framework to architect your next project.

PhoneGap is developed by Nitobi Software which was recently acquired by Adobe. On their website, it says “Build apps in HTML and Javascript and still take advantage of core features in iPhone/iPod touch, iPad, Google Android, Palm, Symbian and Blackberry SDKs.” Currently, PhoneGap v1.3 supports 7 different platforms including iOS, Android, Palm, WebOS, WP7, Symbian and Bada. The framework is open source which means developers and companies can use PhoneGap for mobile applications that are free, commercial, open source, or any combination of these.

What is required to use PhoneGap

PhoneGap projects require the underlying SDKs (e.g. iOS 5 SDK) to be installed and building the project happens from an IDE, such as Xcode 4. Once you have Xcode and iOS 5 SDK installed, download PhoneGap and install it. Open up Xcode and under the New Project dialog, there should be a PhoneGap-based Application project template as shown in Figure 1.

Figure 1

After installing the PhoneGap project template, make sure to build and launch the iPhone simulator. You should see an error in your simulator informing your “index.html” was not found as shown in Figure 2.

Figure 2

In order to fix this, go ahead and copy the ‘www’ directory to the Project Navigator in Xcode. The ‘www’ folder exists in the PhoneGap project folder location. You can quickly go to that folder by right-clicking on the project root in Project Navigator and selecting “Show In Finder”. After you drag the ‘www’ folder, you should see a prompt as shown in Figure 3. Select “Create folder references for any added folders” and click Finish.

Figure 3

Your Project Navigator should look similar to Figure 4.

Figure 4

Now rebuilt and run the iPhone simulator again and you should see similar to Figure 5

Figure 5

Basically, the developer puts his files (HTML, CSS or Javascript) into a ‘www’ folder in the project directory. When building, PhoneGap then renders these files inside a native WebView provided by the OS-specific language (either Objective-C or Java), it exposes access to certain native device features, like Accelerometer, Camera, Notifications, etc.

In a nutshell, a PhoneGap application is essentially still a web application, wrapped inside a WebView. It still remains a web application that is displayed through rendering of HTML, CSS and Javascript using a browser instance on a mobile device.

Appcelerator Titanium

Appcelerator Titanium is another mobile framework to help developers build mobile applications but only on iOS and Android at this time. Similar to PhoneGap, Titanium provides a binding layer that maps Javascript function calls to natively available APIs.

However, Appcelerator claims to be different than PhoneGap in translating Javascript code to native application code. The Javascript code is being interpreted during runtime and through a bridge layer, function calls to Titanium.some_function invoke native application code under the hood.

Another way Appcelerator is different is up until the latest version of Appcelerator, v1.5, you would write your application code in HTML, CSS and Javascript. Now, the application code is written in pure Javascript, using mainly functions that the Titanium API exposes. Apart from using it to access special device features (Camera, Accelerometer, etc), it also enables the developer to render native UI elements (buttons, tables, etc).

These differences give Appcelerator an edge of performance. Just want to emphasize, all the application code will be in Javascript, even the styling of elements happens through function calls. One thing to also keep in mind is to ask yourself will the Javascript API provide all the functionality needed in your application.

Unlike PhoneGap, building and packaging your application does not happen inside an IDE (Xcode, Eclipse, etc), but through their software, Titanium Developer. This is the tool to set up new projects, configure, test and package them. Any IDE of your choice can be used to write the application code.

When choosing a mobile web framework, keep in mind it depends on the requirements of the application when choosing which framework to go with. If the goal is to target many platforms as possible, then PhoneGap may be the right choice. If true native-ness and performance is important, then Titanium may be the choice.

There are many other mobile web frameworks out there that are open source and free and some that charge a developers license fee. I would like to write a follow up blog post on MonoTouch, NimbleKit, AppMobie and others. Stay tuned.