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Silverlight, Back to basics: the User Interface!


I wanted to post a new article in the series about Silverlight (client) and server’s databases. The subject of the article was ‘data forms in Silverlight’. But, because a ‘Data Form’ is the ultimate place where the user directly interacts with the data, and where the concrete sense of a ‘rich user interface’ comes to life… I finally preferred to begin by discussing one of the basic questions: the User Interface (GUI, UI… as it got so many titles and names through the time!)

The UI frontiers

Where does the UI sit inside the entire image of a software project?

Are there any definitive… (kind of ‘waterproof’) frontiers between the UI tasks and the rest of the software project’s tasks?

There is, occasionally, some confusion about this subject. Software industry literature teaches us how to separate ‘objects’ from their ‘presentation’ (‘data’ from ‘views’). But does this mean that building a User Interface should be done in a separate bureau (or on the beach)?...

Although no literature ever discussed the question, such a simplistic approach is applied in some projects in the real world. The concept of separating objects from their presentation is sometimes applied in the form of separating the development processes: Object tasks vs. UI tasks, Object modules vs. UI modules, Object workers vs. UI workers!

Although each task, in any project, has particular skills and knowledge requirements, the success (or failure) of the entire project obviously depends on the global understanding, at all levels, of what the final product is and how its parts articulate.

What is the ‘User Interface’?

To avoid taking the risk of giving a formal definition of what a user interface is, let’s try to define what the user interface’s role is.

In most cases, software solutions propose automated (accelerated) tools for accomplishing well-known human tasks. Most of these tools run using some new ‘media’ (screens, keyboards, mice… etc.). This context implies new ways for representing tasks’ items and new ways for manipulating (processing) theses items. The initial presentation approach was, naturally, to mimic the ‘real world’ way of presenting and manipulating the task items (remember the too large accountancy book displayed on the too small screen… that was probably when the scroll bars have been invented!). Many of today’s iconic presentations still use this approach (just have a look at a ‘button’ and its press/release interaction!)

Presentation (and human-machine interaction process) is largely related to the social and cultural context in a given period or era (objects we use, fashion and elegance trends…). The advent of software and its related objects (virtual and/or material) also affects and participates in the evolution of this cultural and social context. That is why, I think, that a successful user interface is achieved when we mimic the ‘real world’ objects and processes to some extent and, in the same time, instigate new (futuristic) objects and processes (obviously, what may seem ‘futuristic’ today will sooner or later become outdated!).


Anyway, if we may admit that user interface is, briefly, about presenting data through visual graphical objects (controls), then, many new things have to (will) be done at this level!

For example, take the ComboBox: which is basically a selection list of items. With the time going, a selection list can now have several thousands of items… may be we now need a ‘paged combo-box’?... or may be a brand new control to make the selection process easier, faster, less cumbersome…

Many interesting work have been done to solve this kind of concrete problems (you may have a look at some ‘virtualization’ approaches here, here and/or here) fewer have been done for inventing new UI objects (since how many years do we still use: the button, the text-box, the list/combo-box…?)

UI role

From a functional point of view, data presentation (User Interface) role may be summarized as:

§  Give access to different data areas (through menu commands, for example);

§  Show the data;

§  Let the user interact with the data (modify, add, delete…);

§  In some cases, validate the data;

§  Send the updated data back to the data store (server).


In these tasks, the user interface makes use of:

§  Controls to present the data;

§  And transitions (animations or animation-like, between presentation and processing stages).


The success of user interface (in a given era!) is mainly related to the best (harmonious) choice of controls and transitions according to each context of data presentation and/or processing stage.

Silverlight (and WPF) added value

One of the most interesting aspects of Silverlight (and WPF) is that it doesn’t imprison you in a special form of any of its proposed controls. You can, for example, reformat, entirely or partially, the proposed ‘traditional’ ComboBox to make it present the data and behave the way you want. You can, of course, invent something new.

UI controls… the server choice

A UI control presents data. The data is stored and ultimately validated and processed at the server side. So, at the client side, the presented data has a semantic aspect and a presentation (visual) aspect. Although we cannot pretend of any strict rule (valid for all contexts), the data semantic aspect should better be defined at the server side. i.e. questions like: is this a read-only, read/write data?, can the value be omitted (nullable)?, should the value be one of specified choice list items?... etc. should better be defined at the server-side.

The presentation visual aspect (and transitions) should logically be defined at the client side (the UI module).


How can we setup and manage the relationship between the data semantic/visual aspects?

Again, there no ‘all purpose’ rule!

I will present some work on this subject in a following post.

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