--- a/Sources/IncomingHttpRequestFilter.cpp	Fri Jun 11 14:13:36 2021 +0200
+++ b/Sources/IncomingHttpRequestFilter.cpp	Fri Jun 11 14:34:08 2021 +0200
@@ -19,10 +19,10 @@
 
 #include "IncomingHttpRequestFilter.h"
 
-#include "PythonString.h"
+#include "../Resources/Orthanc/Plugins/OrthancPluginCppWrapper.h"
 #include "Autogenerated/sdk.h"
-
-#include "../Resources/Orthanc/Plugins/OrthancPluginCppWrapper.h"
+#include "ICallbackRegistration.h"
+#include "PythonString.h"
 
 
 static PyObject*  incomingHttpRequestFilter_ = NULL;
@@ -117,42 +117,24 @@
 PyObject* RegisterIncomingHttpRequestFilter(PyObject* module, PyObject* args)
 {
   // The GIL is locked at this point (no need to create "PythonLock")
-  
-  // https://docs.python.org/3/extending/extending.html#calling-python-functions-from-c
-  PyObject* callback = NULL;
 
-  if (!PyArg_ParseTuple(args, "O", &callback) ||
-      callback == NULL)
-  {
-    PyErr_SetString(PyExc_ValueError, "Expected a callback function");
-    return NULL;
-  }
-
-  if (incomingHttpRequestFilter_ != NULL)
+  class Registration : public ICallbackRegistration
   {
-    PyErr_SetString(PyExc_RuntimeError, "Can only register one Python incoming-http-request filter");
-    return NULL;
-  }
-  
-  OrthancPlugins::LogInfo("Registering a Python incoming-http-request filter");
+  public:
+    virtual void Register() ORTHANC_OVERRIDE
+    {
+      OrthancPluginRegisterIncomingHttpRequestFilter2(
+        OrthancPlugins::GetGlobalContext(), IncomingHttpRequestFilter);
+    }
+  };
 
-  OrthancPluginRegisterIncomingHttpRequestFilter2(
-    OrthancPlugins::GetGlobalContext(), IncomingHttpRequestFilter);
-
-  incomingHttpRequestFilter_ = callback;
-  Py_XINCREF(incomingHttpRequestFilter_);
-  
-  Py_INCREF(Py_None);
-  return Py_None;
+  Registration registration;
+  return ICallbackRegistration::Apply(
+    registration, args, incomingHttpRequestFilter_, "Python incoming-http-request filter");
 }
 
 
 void FinalizeIncomingHttpRequestFilter()
 {
-  PythonLock lock;
-        
-  if (incomingHttpRequestFilter_ != NULL)
-  {
-    Py_XDECREF(incomingHttpRequestFilter_);
-  }
+  ICallbackRegistration::Unregister(incomingHttpRequestFilter_);
 }