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Friday, February 11, 2011

DataObjects.Net 4.4 goes final

We are very excited to present the final version of DataObjects.Net 4.4. It took almost 5 months of intensive work for our small but brave team to accomplish this task. We tried to include the most awaited features, simplify the overall API and make DataObjects.Net more friendly for desktop application development.

1. Changes comparing with DataObjects.Net 4.4 Beta 2
2. Changes comparing with DataObjects.Net 4.3
3. Download DataObjects.Net 4.4
4. What about the future versions?

Changes comparing with DataObjects.Net 4.4 Beta 2

There are 2 minor changes comparing with Beta 2 version.

Usability of GetProperty/SetProperty
Firstly, the usability of Persistent.GetProperty/SetProperty methods is extended. Both methods now support dot-like notation, for example:

string customerName = orderItem.GetProperty("Order.Customer.Name");

Moreover, both methods support not only publicly visible persistent properties, as it was in earlier versions of DataObjects.Net but all range of them: public, protected, internal and private.

Secondly, we've reworked the localization sample, updated and extracted common interfaces and types into separate assembly 'Xtensive.Practices.Localization'. This feature provides the ability to define localizable entities, localizable fields, describe backing fields for them and execute LINQ queries absolutely transparently.

Here is the example of localizable entity:

public class Page : Entity, ILocalizable<PageLocalization>
 [Field, Key]
 public int Id { get; private set; }

 // Localizable field
 public string Title
  get { return Localizations.Current.Title; }
  set { Localizations.Current.Title = value; }

 // Here localizations are stored
 public LocalizationSet<PageLocalization> Localizations { get; private set; }

Current localization setting is managed via LocalizationScope or Thread.CurrentThread.CurrentCulture property.

// Editing localizable properties through localization scope
using (new LocalizationScope(new CultureInfo("en-US"))) {
        welcomePage.Title = "Welcome!";

// The same action but through Thread.CurrentThread.CurrentCulture
Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");
welcomePage.Title = "Welcome!";

The most valuable part is the transparency of LINQ queries, you don't have to add or change anything. Special query preprocessor, located in 'Xtensive.Practices.Localization', is automatically attached to query processing pipeline and does all the work for you.

Thread.CurrentThread.CurrentCulture = new CultureInfo("es-ES");
using (var session = domain.OpenSession()) {
        using (var ts = session.OpenTransaction()) {

                var query = from p in session.Query.All()
                where p.Title=="Bienvenido!"
                select p;
                Assert.AreEqual(1, query.Count());


In order to add localization support to DataObjects.Net-based projects, follow the instructions in the corresponding chapter in DataObjects.Net 4.4 Release Notes.

Changes comparing with DataObjects.Net 4.3

Better WPF support
DataObjects.Net 4.4 development branch embodies an idea of ORM platform unification for usage in both server-side and client-side applications. Previous version of DataObjects.Net with thread-bound and automatically activated Sessions as well as transactional properties, methods, etc. fits well in server scenarios, but client application development, such as WPF-based ones, might cause difficulties, especially in multi-threaded environment model and delayed binding of windows controls to Entities.

Keeping this in mind, we decided to alter and extend Session behavior. First of all, we made 'Automatic Session activation' and 'Automatic Transaction opening' modes optional, moreover, they are switched off by default. Secondly, in this version we are introducing Session profile notion which represents a combination of predefined Session options for a particular scenario, for instance, WPF application or ASP.NET website.

For now there are three main profiles: Server profile, Client profile & Legacy profile.

1. Server profile is intended to be used in server scenarios, such as ASP.NET, ASP.NET MVC, WCF Data Services, etc. It doesn't include 'Automatic Session activation' and 'Automatic Transaction opening' modes, so several Session instances could be used within a thread and all actions with Entities, Structures & EntitySets require the presence of opened Transaction. This profile is the default one for DataObjects.Net 4.4.

2. Client profile is designed for WPF, Windows Forms, Console applications, whatever. It uses the new 'Disconnected' Session mode which means that Session encapsulates an instance of DisconnectedState and runs in occasionally connected conditions, logs modifications of Entities and applies them to a database on request. It doesn't include 'Automatic Session activation' either but has 'Automatic Transaction opening' option switched on (in this mode it uses local in-memory transactions, not database ones, in order to log Entity modifications).

3. To preserve compatibility with Session & Transaction behavior from previous version of DataObjects.Net we added special profile named Legacy, which has both 'Automatic Session activation' and 'Automatic Transaction opening' modes switched on.

PostgreSQL 9.0 support
Starting from version 4.4 Beta 2, DataObjects.Net provides support for recently released PostgreSQL 9.0. Note, that the 2.0.11 or higher version of Npgsqlprovider assembly is recommended for usage with this version of PostgreSQL.

Visual Basic support
Visual Basic is fully supported starting from DataObjects.Net 4.4. LINQ translator understand and translate properly the following Visual Basic's specific methods for String type: LTrim, RTrim, Len, Left, Right, Mid, UCase, LCase. Auto properties are supported as well. Here is an example model:
Imports Xtensive.Orm

Namespace Model
  Public Class NonPersistent
    Public Property Id As Integer
  End Class

  Public Class Author
    Inherits Entity
    Sub New()
    End Sub

    Public Property Id As Integer

    Public Property Name As String

    Public Property Books As EntitySet(Of Book)

  End Class

F Sharp support
DataObjects.Net 4.4 declares FSharp support. Here is a simple model, written in FSharp. Unfortunately, FSharp doesn't support auto properties as C# & VisualBasic do, so you have to write the appropriate code to emulate them.

module Model
open Xtensive.Orm

  type Person() =
  inherit Entity()

  member this.Id
  with get() = this.GetFieldValue "Id"
  and private set(v: int) = this.SetFieldValue ("Id", v)

  member this.Name
  with get() = this.GetFieldValue "Name"
  and set(v: string) = this.SetFieldValue ("Name", v)

Download DataObjects.Net 4.4

The final version is available for download on the official website.

What about the future versions of DataObjects.Net?

Starting from version 4.5 we decided to review our feature planning policy. Not developers or big bosses will decide what to implement first, but you, our dear customers. Especially for this initiative we've opened a forum on excellent UserVoice service to make the voting and suggestion process natural and agile. The forum already contains all suggestions made on support forum or former issue tracker, but you may add your own ideas as well.

For now, there are 2 features in DataObjects.Net 4.5 branch that were planned earlier:
1. Security System, which was requested by many of you.
2. Firebird data provider, which is almost implemented, owing to the considerable contribution of Csaba Beer.

In addition, we will try switching to the recently published PostSharp 2.1 CTP soon in order to check its declared performance boost and overall stability.

We would like to know your opinion on which features we should include into 4.5 branch. There is a possibility to additionally implement one or two big features (depending on their complexity), so make your choice.


  1. Already make my choice of features requested by me.

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