payment processor plugin questions.

I am writing an eWay responsive redirect plugin (similar to the existing paypal one) and I've found the plugin and code base a pleasure to work with.

I do have one question though. My payment plugin has the following main classes.

public class eWayPaymentProcessor
Public void PostProcessPayment(PostProcessPaymentRequest req)
   var ewayclient = createEwayClient();

   //I need this later!
   var accessCode = ewayClient.AccessCode;


public class eWayPaymentController
public IActionResult HandleResponse(...)
     var ewayClient = createEwayClient()
     var processor = _paymentService.LoadPaymentMethodBySystemName("Payments.eWay") as eWayPaymentProcessor;

      if (processor == null ||  !processor.IsPaymentMethodActive(_paymentSettings) || !processor.PluginDescriptor.Installed)
                throw new NopException("eWay module cannot be loaded");

      var accessCode = ??
      ewayClient.RetrieveTransaction(accessCode)



Now I could store the accessCode in the paymentProcessor, but what happens if there are multiple transactions occuring at once? I'm fairly sure LoadPaymentMethodBySystemName instantiates a fresh object and would not return the correct one.

How can I retrieve sessions parameters and retrieve them? I could store the access code in the return redirect URL but I thought there may be a nicer code only way.

I may not be understanding the issue correctly, but look into utilizing the CustomValues property on ProcessPaymentRequest.