example.cs

public class ResourceGroup:AR
{
    List<string> unprovisionedResources = new List<string>();

    public void ProvisionGroup(string[] ResourceIds)
    {
        foreach (var id in ResourceIds)
        {
            Apply(new UnprovisionedResourceAllocated(this.Id, ResourceId));
        } 
    }

    public void ConfirmResourceProvision(string ResourceId)
    {
        Apply(new ResourceProvisionConfirmed(this.Id, ResourceId));
        if (unprovisionedResources.Count == 0)
            Apply(new ResourceGroupProvisioningCompleted(this.Id));
    }

    public void CheckProvisioningTimeout(string ResourceId)
    {
        if (unprovisionedResources.Contains(ResourceId))
            Apply(new ResourceProvisioningFailed(this.Id,ResourceId));
    }

    public void Handle(UnprovisionedResourceAllocated e)
    {
        unprovisionedResources.Add(e.ResourceId);
    }

    public void Handle(ResourceProvisionConfirmed e)
    {
        unprovisionedResources.Remove(e.ResourceId);
    }
}

public class ResourceProvisioningSaga
{
    IResourceBackend backend;
    IBus bus;

    public ResourceProvisioningSaga(IResourceBackend backend,IBus bus)
	{
        this.backend = backend;
        this.bus = bus;
	}

    public void Handle(UnprovisionedResourceAllocated e)
    {
        backend.AllocateProvisioning(e.ResourceId);
        bus.Raise(CheckProvisioningTimeout(e.groupid, e.ResourceId), When = DateTime.UtcNow.AddMinutes(15));
    }

    public void Handle(MessageFromTheBackendThatProvisioningSucceeded e)
    {
        bus.Raise(new ConfirmResourceProvision(e.groupid, e.ResourceId));
    }

    public void Handle(ResourceGroupProvisioningCompleted e)
    {
        backend.SaveResourceGroup(e.xxx);
    }
}