How could I make my RavenDB application execute properly when UseEmbeddedHttpServer is set to true using 2-tier architecture?

The only way I could reproduce the experience you describe is by intentionally creating a port conflict. By default, RavenDB's web server hosts on port 8080, so if you are not changing raven's port, then you must be hosting your WebApi application on port 8080. If this is not the case, please let me know in comments, but I will assume that it is so.

All you need to do to change the port Raven uses is to modify the port value before calling Initialize method.

Add this RavenConfig.cs file to your App_Startup folder:

using Raven.Client;
using Raven.Client.Embedded;

namespace <YourNamespace>
{
    public static class RavenConfig
    {
        public static IDocumentStore DocumentStore { get; private set; }

        public static void Register()
        {
            var store = new EmbeddableDocumentStore
                        {
                            UseEmbeddedHttpServer = true,

                            DataDirectory = @"~\App_Data\RavenDatabase", 
                            // or from connection string if you wish
                        };

            // set whatever port you want raven to use
            store.Configuration.Port = 8079;

            store.Initialize();
            this.DocumentStore = store;
        }

        public static void Cleanup()
        {
            if (DocumentStore == null)
                return;

            DocumentStore.Dispose();
            DocumentStore = null;
        }
    }
}

Then in your Global.asax.cs file, do the following:

protected void Application_Start()
{
    // with your other startup registrations
    RavenConfig.Register();
}

protected void Application_End()
{
    // for a clean shutdown
    RavenConfig.Cleanup();
}

When you enable the HttpServer in an EmbeddableDocumentStore ravenDB "hijacks" the webapplication and starts listening on the same port that the application is running.

Oren Eini: When you use UseEmbeddedHttpServer from inside IIS, it takes the port from IIS. You need to set the value again

on https://groups.google.com/forum/?fromgroups=#!topic/ravendb/kYVglEoMncw

The only way to prevent it is either turn-ff the raven http-server or assign it to a different port

int ravenPort = 8181;
NonAdminHttp.EnsureCanListenToWhenInNonAdminContext(ravenPort);
var ds = new EmbeddableDocumentStore {
   DataDirectory = [DataFolder],    
   UseEmbeddedHttpServer = true,    
   Configuration = {Port = ravenPort}
};