What is CloudBrowser?

CloudBrowser is a way of rethinking how we write HTML-based Rich Internet Applications, also referred to as AJAX applications. Put simply, the key idea behind CloudBrowser is to keep the entire application, including its data model, (DOM Level 2/3 and JavaScript-based) controller logic, and (HTML-based) view server-side, and use the client-side browser as a (dumb) display device, or thin client, similar to how an X Server displays a remote X client's graphical user. CloudBrowser instances live on a server, and client browsers can connect and disconnect at will, and it is also possible for multiple users to connect to the same instance, which yields a natural co-browsing ability.

With CloudBrowser, we are asking what the effect of this design choice on application development would be. We see a number of key benefits:

• The controller logic becomes non-distributed, much like the logic used in a traditional desktop app (Swing or MFC). In fact, it is identical to the logic that is used when developing the client-side portion in traditional AJAX development.
• There's no need to store UI state in session state so that it can be recreated when a user returns. Much of the usability awkwardness in current AJAX applications results from application developers not saving UI state, or only selectively saving such state. As a result, returning visitors are led back to high-level navigation points - informally, the back button doesn't work, or doesn't properly restore the state the application was in.
• Co-browsing requires no additional developer effort - keeping multiple clients' view in sync is effortless (provided it's ok for all users to see the *very* same page; data-binding mechanisms can be used if multiple server-side browsers' view depends on shared data.)
• Developers can use the high-level JS libraries they're already familiar with, such as jQuery or Knockout.js.
• CSS Works as in traditional AJAX development.
• Live inspection and updating of applications is easily possible.

CloudBrowser is implemented in CoffeeScript/JavaScript using the Nodejs infrastructure and the many libraries existing for it. As a result, the application developer finds a familiar environment, both in terms of language as well as with respect to event-based execution semantics.

FAQ

• How is this different from server-centric frameworks like ZK?

  CloudBrowser shares a number of properties with ZK (and similar server-centric frameworks), such as avoiding client-side code and keeping a representation of the user interface server-side, using a document abstraction. Our work on CloudBrowser was inspired by extensive experience using ZK.

  A key difference is that CloudBrowser does not have a page composition phase and that it does not create a separate 'Desktop' instance for each visitor. This means that users can visit the page as often they like, without having to recompose the page. ZK does not provide any support for remembering a Desktop's state except what the application developer chooses to store in session (or application) state. When a new Desktop is created, the application developer must retrieve that state and influence the page composition logic appropriately. Note that the absence of a page composition phase does not mean templating can't be used when a CloudBrowser instance is loaded.

  A second key difference is that CloudBrowser performs a strict 1:1 mapping between server-side elements and client-side DOM. As a result, styling is much simplified; CSS style rules that refer to classes, ids, and hierarchy apply. Problems like these don't occur.

  CloudBrowser is much simpler on the client-side, because it doesn't support direct access/manipulation of layout attributes. It also does not provide higher-level components (though these can be built using readily available client-side libraries such as jQuery plugins or Bootstrap/JS.

Demos

• Meeting Scheduler Application Source: [HTML and CoffeeScript]
• Chat Room Application [Source]

Check out:

• the code, which includes examples
• Our SPLASH 2012 Wavefront paper
• A Brian McDaniel's MS thesis defense presentation
• 9/14/2002 CS Seminar presentation