DocumentCollection.Open() function not working AutoCAD API

Question

I'm developing an AutoCAD plugin for my application. I'm using AutoCAD 2012. Plugin opens .NET named pipe, and so I can connect to it from my desktop application very easily.

First of all, i have created an interface. Here it is

[ServiceContract]
public interface IConnector
{
    [OperationContract]
    [FaultContract(typeof(Exception))]
    void GetPdfVersion(string filePath, string exportFilePath);
}

My AutoCAD plugin derived from IExtensionApplication interface, so on Initialize method i've written this

this.host = new ServiceHost(typeof(Printer), new[] { new Uri("net.pipe://localhost") });
this.host.AddServiceEndpoint(typeof(IConnector), new NetNamedPipeBinding(), "GetPdfVersion");
this.host.Open();

In one of functions, I need to open document and process it. So, I have written folowing code

var docColl = Application.DocumentManager;
Document curDraw = null;
try
{
    if (File.Exists(@"d:\1.dwg"))
    {
        curDraw = docColl.Open(@"d:\1.dwg", true, string.Empty);
    }
}
catch (Exception e)
{
    Console.WriteLine(e);
}

But it throws a COM exception, on the curDraw = docColl.Open(@"d:\1.dwg", true, string.Empty); code, with HRESULT=-2147418113

I need Document object for processing the dwg file. Is there any possible ways to fix that error?

Answer 1

AutoCAD can't work with document object from external thread. That's the root of the problem. If I write method and put an CommandMethodAttribute - it will be work, but only from AutoCAD console... But, what if I need to do this operations from external application? First of all, need to specify the attribute on service behavior class

[ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Single, IncludeExceptionDetailInFaults = true)]

Thus be used only one thread for all operations.

The next step, in Initialize() method get the CurrentDispatcher object and put it in static variable.

private static Dispatcher dispatcher;
public void Initialize()
    {
        dispatcher = Dispatcher.CurrentDispatcher;

        this.host = new ServiceHost(typeof(Printer), new[] { new Uri("net.pipe://localhost") });
        this.host.AddServiceEndpoint(typeof(IConnector), new NetNamedPipeBinding(), "GetPdfVersion");
        this.host.Open();
    }

by this way, control of autocad execution context can be achieved. The next step is invoke the method through dispatcher

public void GetPdfVersion(string filePath, string exportFilePath)
    {
        dispatcher.Invoke(new Action<string, string>(this.GetPdfVer), filePath, exportFilePath);   
    }

So, by using this method, I can run code, contained in GetPdfVer method from external application and get all benefits of using WCF instead of COM-interaction.