Last post we discussed several different XML markup languages for user interface definition looking for a candidate language for designing and constructing storyboards or at least assist in building a simple storyboard designer if no suitable storyboarding applications exist.  I hinted that I found a candidate.  It looks like XAML is good language candidate.  A concise overview of this technology can be read in a recent Forrester article called, WPF Will Dominate Rich Client Development.  Carl definitely gets it.

WPF stands for Windows Presentation Foundation which is Microsofts new user interface presentation technology that runs on Windows XP and Vista through WinFX runtime components. eXtensible Application Markup Application or XAML is the design-time language that is suitable for defining and construction user interfaces and workflows that are separate from code-hind (e.g. C#) as this is the code interface separation point, sometimes referred to as the plug-in interface. That means the user interface and workflow definitions are 100% portable and are distributed through a standard plug-in package (i.e. XAML).  XAML can be shared between XAML design-time applications without any translation cost or loss of fidelity.  XAML can also be run on Microsofts new application execution environment, WPF for business user presentation of the user interface and WF for run-time workflow execution.

 

One very interesting paragraph in the article is, The key is that XAML is a description of the user interface, not an abstraction of the user interface.  This is a subtle but critical distinction.  Other XML-based user interface (UI) languages, such as User Interface Markup Language (UIML), have attempted to describe the common capabilities of multiple UI technologies or even devices, and in order to do so, they must abstract the specifics of a given platform into a common generic format.  Inevitably, something gets lost in translation. XAML makes no claim to universality; it describes Windows user interfaces.

 

Telling statement lost in translation.  While I was thinking of having my storyboarding application generate multiple user interface implementations for different platforms as a goal, it now seems unrealistic.  The reality is that most business applications are written with a Windows user interface, which ultimately is my target audience.  The fact that XAML describes a design-time Windows user interface description using an XML markup language that is completely separate from code-behind is a key technology trait required for toolability which is one of the key concepts behind why XAML

 

Carls article further states, picture a prototyping tool that could be used by usability specialists to rapidly prototype and test designs. Authors note: hey, thats my idea! Users could also consider defining web server based process flows and integrations in a business process tool and then easily handing off specifications for the interfaces of individual services to a programmer who will populate them in Visual Studio.  Interestingly enough, it is no surprise that business workflows can also be defined (just recently) using XAML in Windows Workflow Foundation. 

 

Next post we will explore a number of designer applications and tools for rapidly defining business user storyboards using, or can output XAML.  First we will look at Microsofts Orcas Cider as a CTP XAML designer in Visual Studio 2005 and the first CTP release of Expression Interactive Designer (aka Sparkle) which is a standalone product.