调用l2行情数据api接口如何做？这个方式用起来比较简单，这种通达信l2行情接口通常是指HTTP接口，也可以说是HTTP API，URL为接口的地址，HTTP方法指的是GET, PUT, DELETE等等。一般来讲，调用通达信L2接口，都需要代码接入：
public interface IFeatureControl { }
public sealed class FeatureControl : IFeatureControl
{
public static IFeatureControl Current { get; }
static FeatureControl()
{
if (Current == null)
{
Current = new FeatureControl();
}
}
}
[TestFixture]
public class FeatureControlTests
{
[Test]
public void IsFeatureControlSingleton()
{
IFeatureControl c1 = FeatureControl.Current;
IFeatureControl c2 = FeatureControl.Current;
Assert.AreSame(c1, c2);