Hit The Road Jack...

WCF 4.0 Routing with WAS

A few days ago I wanted to build a simple message broker so I’ve decided to tryout the new routing feature WCF 4.0 is offering. When doing so I’ve encountered two problems:

The first problem was that I needed to figure out a way on how to do the routing when hosting the services under WAS (Windows Process Activation Service) since I’ve been using netTcpBinding for my services.

And the second problem was how to do XPath Message Filtering on a service operation parameters (not a Data Contract).

I’ve googled a bit on WCF 4.0 Routing but I didn’t find any samples on routing when hosting WCF in WAS. And as regards to my second problem I only came up with samples of Message Filtering only on a Data Contract.

Let’s see how to resolve this problems, to demonstrate the resolutions I’ve created a small test project called WcfTestRouting as my test case project.

First lets create the service contract and the services.

As you can see I’ve added two operation contracts: one receiving a Data Contract and the other receiving just primitive method parameters.

Now I’ve added two services which I wanted to route between.

The Account Manager Service (AccountManager.svc):

And the Account Manager VIP Service (AccountManagerVip.svc):

The difference between them is that the first one returns: Failed, “Regular” and the second one returns: Successful, “Vip”;

In order to deploy the services in WAS we need to do the following steps:

First, add the following service element under the services element in your web.config (you’ll need one for each service of course):

Second, configure your Web Application to allow net.tcp bindings, choose your Web Application in the IIS management console and click on the advanced settings Action:

You’ll receive the following window:

Make sure that under Behavior / Enabled Protocols, you have also a definition for “net.tcp” protocol.

Now for the routing configuration:

First let’s add the two client endpoints in the web.config file:

Then add the routing definitions:

After that, we need to add the routing service. Since the routing is done using System.ServiceModel.Routing.RoutingService and we are hosting the service under WAS, you need to expose it as a valid URI in your Web Application hosting the other WCF services (This can be done also in a separated Web Application). In order to do that add a blank svc file called AccountManagerRoutingService.svc to your Web Application, you can do that by simply adding a text file and changing the extension to svc.

Open the file and add the following:

This will create the route service with a valid URI you need in order to be able to do the routing in your WCF application.

Then add a service definition in your web.config as we’ve done with the previous services:

Don’t forget to add the following line in the service behavior configuration:

This will allow the routing to be performed also by inspecting the message body and will associate the route service it with the desired filter table.

In order to test this I’ve also written a Console Application consuming the service. Just note that when adding a Service Reference don’t add it to the Routing Service, since the routing service implements another service contract (IRequestReplyRouter) we need to add the Service Reference to one of the original services implementing our service contract (IAccountManager).

A resulting test would look something like this:

In order to make this work against the Router Service we need to change the endpoint address in the clients app.conifg file. Therefore the endpoint address should be net.tcp://localhost/WcfTestRouting/AccountManagerRoutingService.svc and the client’s binding would look like this:

Note that the client is using to the IAccountManager Service Contract.

Now when applying a different account id – the service will be routed as configured in the routing section.

The second problem was how to apply filtering when using primitive parameters in the service operation. For example when using the following operation:

The trick is very simple, lets have a look again at the filter definition in the routing section:

As you can see I’ve added the http://tempuri.org/ to the namespaceTable and used it as the prefix for the filter data. This is due to the fact that when the Namespace is unspecified in the Service Contract it defaults to http://tempuri.org/ .

SDP – ORM Day

Just a reminder for the Sela Developer Practice Conference, on the 28th we're having a whole day on ORM:

We'll (Erez Harari, Ido Flatow, Gil Fink and myself) be presenting the following sessions:

Part 1 – ORM and Entity Framework
Part 2 – Comparing ORMs
Part 3 – Entity Framework Deep Dive
Part 4 – Real World Data Access with ORM
Part 5 – Best Practices – Experts Panel

Also I’m glad to say that Oren Eini has accepted my invitation to join our Experts Panel (everyone else but me are all about EF 4.0 so I need some reinforcement on the NHibernate side ) so I’m sure it's going to be interesting.

Real World Data Access with ORM at the upcoming SDP

Erez and I are going to give a P&P (Patterns and Practices) Lecture at the upcoming Sela SDP on the 28^th of December.

ORM’s are great tools and they can give you a lot of value in your apps. But and there is a but, when mistreated they will just complicate things for you.

We are going to talk about some of the patterns that ORM’s are built upon and other patterns complementing the use of ORM’s.

And last but not least, a lot of Real World Code Examples and Demo’s(Yes, we are going to show code – so beware) of how this patterns are implemented and used.

Be there or be square

A Quest With EF 4.0 (Entity Framework) And NHibernate Part 2

Usually I don’t really like generated stuff, somehow it seems like I always reach a certain point where I start cursing the $#$%@! wretched generator. So this post will be all about POCO (Plain Old CLR Objects) using just objects. This time I’ll start from the NHibernate Perspective.

Lets consider the following Model (Continuing from my previous post):

It was quite easy to do even with NHibernate – just write a bunch of classes like:

public class User
{
  private IList<Category> _categories = new List<Category>();

  public virtual string Username { get; set; }
  public virtual string Password { get; set; }
  public virtual string FirstName { get; set; }
  public virtual string LastName { get; set; }

  public virtual IList<Category> Categories
  {
    get { return _categories ; }
    set { _categories  = value; }
  }
}

Write an hbm (mapping) file:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping
  xmlns="urn:nhibernate-mapping-2.2"
  assembly="Sample.DomainModel"
  namespace="Sample.DomainModel">
  <class name="User" table="Users" >
    <id name="Username" length="255" type="System.String" >
      <generator class="assigned" />
    </id>
    
    <property name="Password" />
    <property name="FirstName" />
    <property name="LastName" />

    <bag name="Categories" 
         table="UserCategory" >      
      <key column="Moderators_Username" />
      <many-to-many class="User" 
                    not-found="ignore" 
                    column="Categories_Id" />
    </bag>    
  </class>
</hibernate-mapping>

And that's about it, you have a simple and persistable object.

The following test will show you how easy it is to do some basic operations on the User entity I’ve created, such as creating a new one, loading an existing one and deleting the entity

public void CreateAndDeleteUserTest()
{
  string username = "myusernamefortest";
  string firstName = "SomeFirstName";

  using (ISession session = OpenSession())
  using (ITransaction trn = session.BeginTransaction())
  {
    var usr = new User
                 {
                    FirstName  = firstName,
                    LastName = "SomeLastName",
                    Username = username,
                    Password = "SomePaswword"
                 };

    session.Save(usr);

    trn.Commit();
  }


  using (ISession session = OpenSession())
  using (ITransaction trn = session.BeginTransaction())
  {
    var usr = session.Load<User>(username);
    
    Assert.IsNotNull(usr);
    Assert.AreEqual(usr.FirstName, firstName);
    
    session.Delete(usr);

    trn.Commit();
  }
}

Now, can it be done with EF 4.0?

Let’s have a look:

First I Created a Project called “Sample.DomainModel.POCO” this is where I want to create Persistence Ignorant Objects so I’ve added the following classes:

User, Category, Message and Thread.

And got the following model (quite similar to the one at the beginning of this post):

Now I’ve Created a Project to hold the EDM –> “Sample.DomainModel.EF”

I’ve added an EDM file to the project (Right Click, Add new item, ADO .NET Entity Data Model). and named it SampleModel.edmx.

This time I was a bit lazy (or deferred, if you like the MS jargon) and I’ve chosen to generate the model from the database, In my last post I’ve generated the model from the EDM, so I’ve decided to use the same one.

And following the instructions from the following post in the ADO .NET Team Blog, I’ve done the following on the properties of SampleModel.edmx I’ve erased the CustomTool Entry and left it blank.

Now I’ve added the to “Sample.DomainModel.EF” the ForumsEntities class :

public class ForumsEntities : ObjectContext
  {
    private ObjectSet<Category> _categories = null;
    private ObjectSet<User> _users = null;
    private ObjectSet<Thread> _threads = null;
    private ObjectSet<Message> _messages = null;

    public ForumsEntities()
      : base("name=ForumsEntities", "ForumsEntities")
    {
      _categories = CreateObjectSet<Category>();
      _users = CreateObjectSet<User>();
      _threads = CreateObjectSet<Thread>();
      _messages = CreateObjectSet<Message>();
    }
    
    public ForumsEntities(string connectionString)
      : base(connectionString, "ForumsEntities")
    {     
    }  

    public ObjectSet<Category> Categories 
    {
      get 
      {
        return _categories;
      }
    }    
    public ObjectSet<User> Users
    {
      get
      {
        return _users;
      }
    }

    public ObjectSet<Thread> Threads
    {
      get
      {
        return _threads;
      }
    }

    public ObjectSet<Message> Messages
    {
      get
      {
        return _messages;
      }
    }
  }

And that's about it. I’ve run the same tests I’ve used in my previous post, and for my surprise it actually worked!

Summing up, at least from the basic point of view it is not that hard now to implement POCO with EF 4.0 which makes it a bit more appealing for me, although from what I’ve read at the ADO .NET team blog there are some issues using POCO in regards to Inheritance when using Proxies (Which is also an issue with NHibernate), Change Tracking, and probably in a real life project some other tweaks will occur.

A Quest With EF 4.0 (Entity Framework) And NHibernate Part 1

I’ve been using ORM for some time now, and I have quite an acquaintance with NHibernate from its first days, thanks to Oren Eini AKA Ayende. For the last few months with the upcoming buzz on VS 2010 and .Net Framework 4.0 I had a some discussions with colleagues of mine regarding what would be the best choice for an ORM tool should we use a well known and mature solution like NHibernate or should we follow the crowd on the Microsoft path? Personally I think that this kind of questions are a bit like religious questions when you have zealots from each direction. Therefore I’ve decided to start and investigate the issue on my own and try my best to do an unbiased comparison between the two.

In my place of work we have a great team of professionals but we are lacking with a quite basic tool for collaborating Information between each other (a forum), so my test case will be on a simple forum for our consultants group at Sela Technology Center.

From my perspective EF v1 was really premature, so I’m starting my quest with EF 4.0 (Also I like having some fun with new stuff).

In my first attempt to use EF 4.0 I’ve wanted to use the Model First support – this way I can model my domain and than create the underlying database, from my experience this would be a better approach when you are starting a new application from scratch (although in most real life scenarios you would probably have some kind of a legacy database from which you’ll start modeling your domain).

I’ve modeled my domain to the following structure:

Then all you need to do is right click on your EDM designer and choose “Generate Database Script From Model…”

This will produce a script that you can run and generate the appropriate tables and constraint in the database (Currently this feature only works from MS SQL Server 2005 and 2008).

If you’ve ever had to design an application with the database schema as well, this feature can save you quite some time going back and forth between your model and database. Unfortunately my first attempt was unsuccessful, I’ve kept getting errors when trying to create the ObjectContext (maybe this feature will work better in the release) so I’ve started again with a simpler model, that looks like this:

This attempt actually worked so I’ve proceeded with completing my model to desired result.

The nice things about this is that when generating the script (or regenerating after making changes to the model) also the MSL (Mapping Specification Language) is automatically configured with the correct mappings.

So far so good, but does this really work? I’ve written a simple console app and added a few tests AddUser, AddCategories and GetCategoriesFromRoot. For the meantime I’ve decided to avoid getting into testability issues (although this is quite a major issue when thinking about DDD).

private static void AddUser()
{
  using (ForumsContainer context = new ForumsContainer())
  {
    User user = new User
                {
                  Username = "user1",
                  Password = "password",
                  FirstName = "SomeFirstName",
                  LastName = "SommeLastName"
                };

    context.Users.AddObject(user);
    context.SaveChanges();
  }
}

private static void AddCategories()
{
  using (ForumsContainer context = new ForumsContainer())
  {
    User moderator = context.Users.FirstOrDefault((item) => item.Username == "berniea");
    Category cat1 = new Category
    {
      Id = Guid.NewGuid(),
      Parent = null,
      Title = "Category 1 Title",
      Description = "A long description",
      Moderators = { moderator },
      Children = { new Category
                    {
                      Id = Guid.NewGuid(),
                      Title = "Sub Category 2 Title",
                      Description = "A long description",
                      Moderators = { moderator }
                    },
                    new Category
                    {
                      Id = Guid.NewGuid(),
                      Title = "Sub Category 3 Title",
                      Description = "A long description",
                      Moderators = { moderator }
                    }
                 }
    };
    context.Categories.AddObject(cat1);
    context.SaveChanges();
  }
}

private static void GetCategoriesFromRoot()
{
  using (ForumsContainer context = new ForumsContainer())
  {
    context.ContextOptions.DeferredLoadingEnabled = true;

    var cats = from cat in context.Categories
               where cat.Parent == null
               select cat;

    foreach (var item in cats)
    {
      Console.WriteLine("Category Name: {0}", item.Title);
      foreach (var childCat in item.Children)
        Console.WriteLine("\t Child Cat Name: {0}", childCat.Title);
    }
  }
}

Doing something similar with NHibernate is also possible just without the nice designer, unfortunately it will require some coding .

NHibernate will generate the database schema from the mappings (hbm files) and you’ll still have to code your own classes, which is not necessarily a bad idea (if your really lazy there’s a contrib project that generates classes from hbm files).

I’ve created the same model (just classes and mapping files):

A few mapping files like Category.hbm.xml:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" 
                   assembly="Sample.DomainModel" 
                   namespace="Sample.DomainModel">
  <class name="Category" table="Categories" >    
    <id name="Id" type="System.Guid">      
      <generator class="guid" />
    </id>    
    <property name="Title"  />
    <property name="Description" />    
    
    <bag name="Moderators" table="UserCategory" >
      <key column="Categories_Id"/>
      <many-to-many class="User" not-found="ignore" column="Moderators_Username" />
    </bag>
    
    <many-to-one name="Parent" class="Category" column="Parent_Id" 
                 not-found="ignore" not-null="false"/>

    <bag name="Children" table="Categories" lazy="true" 
         cascade="save-update" inverse="true">
      <key column="Parent_Id"/>
      <one-to-many class="Category" not-found="ignore" />
    </bag>    
  </class>
</hibernate-mapping>

And the rest (not REST) is history, or just a few lines of code:

public void CreateSchemaFromConfig()
{
  var script = new StringBuilder();

  Configuration cfg = GetConfiguration();
  
  new SchemaExport(cfg)
      .Execute(s => script.AppendLine(s), false, false);

  string wholeScript = script.ToString();

  Console.WriteLine(wholeScript);
}

This will produce an SQL script a a bit similar to the one produced by the EDM designer, also you can do a SchemaUpdate after making changes to your model.

Host your own WPF Designer

Last week I had to find a WPF Designer which can be hosted in a .Net application, the result of my brief research was Aurora XAML Designer. As far as I sow it isn't possible to host cider (VS WPF Designer) in your own application so lucky for me I found a reasonably good alternative in Aurora XAML Designer.

I've contacted Patrick from Mobiform and he was kind to send me a Trail Version for me to test. The result looks quite promising when I was able to easily take control of different parts of the designer such as manipulate the Toolbox create Tool-bars Pans and so on. Eventually it seems like a nice solution if you want to enable the end user to edit / create simple WPF forms from your application without having to install Visual Studio or Expression Blend.

Here are some pictures of my own self hosted Aurora XAML Designer:

Extending your C# application with IronPython