Add an interface for websocket specific transport methods.

src/GraphQL.Client.Abstractions.Websocket/IGraphQLClient.cs

@@ -0,0 +1,19 @@
+namespace GraphQL.Client.Abstractions.Websocket;
+
+public interface IGraphQLWebSocketClient : IGraphQLClient
+{
+    /// <summary>
+    /// Publishes all exceptions which occur inside the websocket receive stream (i.e. for logging purposes)
+    /// </summary>
+    IObservable<Exception> WebSocketReceiveErrors { get; }
+
+    /// <summary>
+    /// Publishes the websocket connection state
+    /// </summary>
+    IObservable<GraphQLWebsocketConnectionState> WebsocketConnectionState { get; }
+
+    /// <summary>
+    /// Explicitly opens the websocket connection. Will be closed again on disposing the last subscription.
+    /// </summary>
+    Task InitializeWebsocketConnection();
+}

src/GraphQL.Client/GraphQLHttpClient.cs

@@ -6,7 +6,7 @@
 
 namespace GraphQL.Client.Http;
 
-public class GraphQLHttpClient : IGraphQLClient, IDisposable
+public class GraphQLHttpClient : IGraphQLWebSocketClient, IDisposable
 {
     private readonly Lazy<GraphQLHttpWebSocket> _lazyHttpWebSocket;
     private GraphQLHttpWebSocket GraphQlHttpWebSocket => _lazyHttpWebSocket.Value;