Package Pages, User Controls, and Master Pages for Reuse

Monday, July 31, 2006 by scott

Graham Dyson has an interesting project named WAPUL:

"WAPUL is a part of a project I've been developing for creating libraries of user controls, pages and master pages (although currently no support for a master page using another master page). Its aim is to avoid bodging or extra leg work when distributing (i.e. just one .dll file)."

Sharing controls and pages is a feature many people are looking for. Graham has a clever solution using code, a post-build step, and the aspnet_merge tool.

Dependency Property Notes

Friday, July 28, 2006 by scott

I've run into dependency properties in both Windows Presentation Foundation and Windows Workflow Foundation. In trying to understand what they do, I ran across Drew Marsh's excellent introduction - "Avalon: Understanding DependencyObject and DependencyProperty". Drew's article has a WPF slant and I've mostly been seeing dependency properties from the workflow side.

In WF, dependency properties enable three features:

  • Attached properties
  • Activity binding
  • Meta properties

The attached property story in WF is similar to the attached property story in WPF - a parent object can add additional state to the children it manages. A WPF grid will attach Row and Column properties to its children. The dynamically attached properties allow the grid to store layout state in each child. In WF, the Conditioned Activity Group can attach a When property to each child. The When property holds a condition for the CAG to evaluate before running a child activity.

Activity binding gives a dependency property an ActivityBind object to evaluate when asked for its value. The ActivityBind can point to other fields, properties, or methods of activities inside a workflow. One activity could bind its input properties to a previous activity's outputs. Binding makes the data flow a part of the workflow model.

The behavior of meta properties caught me off guard. There are two types of dependency properties in WF activities: meta properties and instance properties. We set meta properties at design time and cannot change their value at runtime (they can't use binding, either). I think meta properties exist to guarantee the integrity of an activity. At runtime, I can't change the InterfaceType of a CallExternalMethod activity and screw up the rest of the parameter bindings because InterfaceType is a meta-property.  

Dependency properties are easier to understand once you see the use cases. You have to wonder if we'd be talking about dependency properties a all if the mainstream CLR languages were more dynamic.

Review of the Creative Zen Vision:M

Thursday, July 27, 2006 by scott
1 comment

I'm the owner of a new 30GB Zen Vision:M. The Vision:M is a portable media center and plays both MP3s and videos. The unit currently retails between $269 and $299.

The 320x240 2.5'' LCD display looks remarkably good, even with the brightness setting at 50%. The Vision:M is a bit thicker and heavier compared to its iCompetitor, but has more color (262k versus 65k), and supports more file formats (DivX, XviD, MPEG 1/2/4, and WMV all play). I'll take function over form. The rechargeable Li-Ion battery lasted over 10 hours on a mix of video and audio (mostly audio).

I did not install the bundled software. Windows Media Player 10 recognized the device and synchronized content without any fuss. I've synched music, TV shows from a Media Center, and movies in WMV and DivX format. Of course, not everything you can record with Media Center will synch with an external device, thanks to the pinheads at the MPAA.

The only problem I've had is with an MSDN web cast. It seems there is an extra stream in the web casts and the stream confuses WMP. Fortunately, Marauderz M2PMCEncoderZX converts the MSDN file, and adds some additional options for anyone who is unhappy with the default conversion settings WMP uses for portable media centers.

The Vision:M synchronizes and charges through a USB connection, but requires a small dongle to adapt the USB connector to the unit itself. A full USB re-charging takes about 4 hours. The dongle includes connections for a charging with a DC adapter, and an A/V out. Creative made life more difficult (and more expensive) by not using a standard camcorder pinout for the 3.5mm AV jack. A little bit of splicing can work around this problem.

A touch pad on the front scrolls through menus. It can take some time to become accustomed to the touchpad, but the sensitivity is adjustable. The Vision:M also includes a microphone and FM stereo receiver (but no line input). A PIM is included that will sych with Outlook, although I haven't tried this feature (it requires an install of the bundled software, which I've have not tried).

Overall, thumbs up for the Creative Zen Vision:M.

Narrative JavaScript

Wednesday, July 26, 2006 by scott

I stumbled across Narrative JavaScript this weekend.

NJS uses a compiler to generate asynchronous JavaScript from procedural JavaScript. You write simple code with local variables and blocking operations. NJS takes the simple code and spits out JavaScript with all the callbacks and asynchronous goo. It's like programming with continuations.

I wonder if Nikhil could add something like this to ScriptSharp.

Pickup Lines In .NET

Tuesday, July 25, 2006 by scott

Imagine if everyone in the world knew .NET programming. The world might be a bit strange, but at least these pickup lines might work.

If I were a generic collection, I'd be strongly typed for you.

You must be the latest version, because I've been checking you out.

I have a small problem. I put an object in a Dictionary, but I lost the key! Can you come back to my place and help me look for it?

A TypeConverter just returned my heart, and it's ready to assign to you.

Let's turn off option strict and do some late night binding.

So, what's your hash code?

It's Getting Crowded in the ThreadPool

Monday, July 24, 2006 by scott

It seems everybody loves the thread pool. The default scheduler in Windows Workflow uses the thread pool, as does ASP.NET and the BeginInvoke method of every delegate. There is only one pool per process, which seems a bit limiting with such a big party inside.

Joe Duffy says there is a lot of work going into improving the ThreadPool in future versions of the base class library, I wonder if future versions will allow for some partitioning of work. .

A couple people have asked me about custom thread pools. I do see the need in some scenarios, but writing a custom thread pool is hard. I generally point people to custom thread pools that smart people have already built:

Jon Skeet has a custom thread pool class on this page. The pool is configurable and allows you to separate your threads from the threads in the system pool.

Mike Woodring has a custom thread pool available on this page. The thread pool is configurable, instrumented, and has a great many features.

On The Internet, Nobody Knows You’re Guilty

Friday, July 21, 2006 by scott

Information week has been covering the trial of a sysadmin accused of sabotaging 1,000 UBS Paine Webber servers. There is an abundance of circumstantial evidence in this case. Investigators found a printout of malicious code in the defendant’s bedroom, and the defendant bought an outstanding amount of stock puts that would benefit from a drop in UBS's price. Direct evidence, however, is from the ephemeral world of 1s and 0s: VPN logs, tape backups, and server audit trails. The defense called all these technologies into question.

Wolfe also used his closing arguments to attempt to rebut defense theories. Chris Adams, Duronio's attorney, has argued that hackers could have been responsible for the attack. He also argued that another systems administrator … did the attack, or that it was a penetration test gone awry by Cisco Systems. The attorney at different times went after the first forensics company to work on the case, @Stake Inc., saying that they couldn't be trusted because hackers worked for the company. Then he claimed the U.S. Secret Service, called in to investigate the case, did sloppy investigative work, as did the government's forensics expert. The defense's forensics expert … testified that he couldn't be sure that the logic bomb was responsible for the damage to the UBS system.

The defense went wild with conspiracy theories. When 40 people have the root password it’s easy to raise a shadow of a doubt. Even if the systems recorded biometric information, would you still trust an audit log? A rouge admin could alter any bit on a computer. The jury in this case found the defendant guily of securities and computer fraud on Wednesday. He'll face a maximum sentence of 6.5 to 8 years.

If you had to decide the fate of a person, what technologies would you trust as reliable sources of evidence?

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