Tuesday, 14 August 2012

Data virtualization in Silverlight

When I first went freelance (15 months ago – how time has rocketed by!) I promised myself that, with the reigns of my schedule tightly held in my own fist, I would dedicate more time to blogging. Well! You can all see from my blog archives how that turned out. I have discovered that when you have clients willing to pay for as much time as you can give them, there’s a strange temptation to give them as much time as you’ve got!


Just before I went on vacation last week, I found made the time to write a mini-blizzard of blog posts, though not for Functional Fun. Ayende, my client for the last few months, has published them on his company’s blog. In the first batch, I wrote about some exciting new features I’ve coded up for the user interface of RavenDb, Hibernating Rhino’s Document Database server.

But I think you’ll most enjoy a couple of posts I wrote about data virtualization in Silverlight. The problem is a common one. How do you display huge lists of data items in a client application without pulling data unnecessarily from the server? Often applications fall back on paging – show one page of data, and make the user click a Next button when they want to see more. But in terms of usability, this technique feels pretty neolithic. So I figured out a way of using ListBoxes and DataGrids without needing to load all the data up front, but with properly proportioned scrollbars, slurping data from the server just in time as the user scrolls.

Over on Hibernating Rhino’s blog you’ll find the two posts I wrote about this:

There’s also a bonus post on how I created a VirtualizingWrapPanel for Silverlight – built so that we could display data in a card view rather than a list view.

And best of all, I published a sample application on GitHub with all the code you need to use this technique in your own applications. For those WPF-aficionados amongst you, you should find that the code translates without much difficulty.