PersistentDictionary implementation is based on Esent, which is a not well-known embedded database included in all major windows version (XP, Vista, Windows Server, etc).  From the Microsoft Windows SDK blog:

ESENT is used by the Active Directory, Windows Desktop Search, Windows Mail and several other Windows services and a slightly modified version of the code is used by Microsoft Exchange to store all its mailbox data. The ESENT API is available through the SDK and can be used on all versions of Windows from Windows Server 2000 on up

There is a managed wrapper for Esent, part of which is also an implementation of PersistentDictionary. Out-of-the box, the PersistentDictionary implementation only stores simple structures and primitive data types, but it is very easy to modify it to support also classes, which are marked with the [Serializable] attribute. One just needs to change the ColumnConverter class. For your convenience, here is the compiled version of EsentCollections, which enable just that. The usage is fairly simple.

var store = new PersistentDictionary<Guid, MyClass>("test-database");
// save an instance of your class
store[Guid.NewGuid()] = new MyClass { PropertyA = "SomeValue" };

// to retrieve and display all elements, you can
foreach(var key in store.Keys) {
  var retrievedInstance = store[key];
  // now do something with this instance
  Console.WriteLine(retrievedInstance.PropertyA);
}

You have to ensure, though, that your custom class is marked for serialization. You can achieve this like so:

[Serializable]
public class MyClass {
  public string PropertyA { get; set; }
}

You can see that it is very easy to implement simple repositories on top of that — for prototyping needs, where the entities are constantly evolving and changing.

Do note, however, that Esent is not limited to PersistentDictionary. You can query it in different ways, add indexes to it, have many columns, etc. The thing is used by large-scale software like Exchange, nontheless.

I will post a simple example of IRepository implementation shortly. Stay tuned!

I am by no means a gamer (don’t play, never did a lot (except for Tetris (the original one), The Incredible Machine, and maybe something else) but was fascinated by Crayon Physics Deluxe. I’ve been setting up my father’s and my sister’s computer (they’ve bought themselves an MSI multi-touch all-in-one PC AE2220M) and found an interesting application in the Windows 7 Touch Pack: Blackboard. It reminded me of The Incredible Machine, a DOS-based game in the early nineties. Refreshing the fond memories of TIM, I read the Wikipedia article about it, where I saw the game Crayon Physics Deluxe mentioned. When I saw the demo (the video recording), I downloaded a trial and bought the game. I do own a tablet, and I’m testing it on my kids tomorrow (they are not allowed to work computer otherwise).

With regards to the multi-touch all-in-one PC: it is solid built, the sound is not so great, and the keyboard is too small for my taste and feels very plastic — it is wireless, on the other hand. Otherwise, it’s quite good consireding the price (720 EUR + VAT), sporting a dual core CPU, 4GB of RAM and 640GB of hard disk space. A quality keyboard would’ve made the difference, in my opinion, since the rest of the computer feels quite solid.

Since I’ve had this problem before, and I discussed it with Dejan, I started digging through all of my email correspondence with Dejan, but could not find anything. I checked and changed the collation of a database, still nothing. My best friend, Google, was of no help either. It then struck me. Varchar. It is non-unicode data type. nvarchar is of course, what was needed to fix the problem. It is intriguing though, that all of the other Slovene characters work, but c with caret (č) does not get corrupt as one would expect, but gets converted to c.

A lesson learned, is a lesson earned, I guess. This post is here to remind of this situation next time.

Stanovanje smo vmes že prodali.

USE MASTER
GO

ALTER DATABASE moovme SET SINGLE_USER WITH ROLLBACK IMMEDIATE
ALTER DATABASE moovme COLLATE Slovenian_CI_AS
ALTER DATABASE moovme SET MULTI_USER
GO

Hope that helps anyone.

Both YSlow and Page Speed require the excellent Firebug extension, which is an essential tool for web developers. If you don’t know YSlow or Page Speed yet, now is the time to get acquainted.

• ajax views
• route debugging
• menulink helper
• error handling (controllers, views, customization)
• different view results (RSS view result among them)
• model binding
• custom controller factory with a simple Autofac dependency injection demo
• custom view engine (showing how mobile pages can be served by using MDBF) and
• client & server side validation using the interesting xVal framework.

Get all demos in one zip archive