followup change: fix dummy webserver

the dummy server was no longer working after server rework

dummy.py

@@ -2,12 +2,18 @@ import time
 import math
 import io
 from colors import assign_colors_to_curves
-from secop import SecopInstrument, SecopClient
-from base import get_abs_time
+from secop import SecopClient
+from base import get_abs_time, HandlerBase
 
 
-class DummyGraph:
-    def __init__(self):        
+class DummyGraph(HandlerBase):
+    def __init__(self, server, instrument, device, tags):
+        super().__init__()  # put methods w_... to handlers
+        self.handlers['graphpoll'] = self.graphpoll
+        self.server = server
+        self.instrument = instrument
+        self.device = device
+        self.tags = tags
         self.blocks = []
         self.phase = {}
         self.end_time = 0
@@ -158,11 +164,7 @@ class DummyGraph:
         return None
 
 
-class SecopDummyClient(SecopClient, DummyGraph):
-    def __init__(self, instrument):
-        SecopClient.__init__(self, instrument)
-        DummyGraph.__init__(self)
-
+class SecopDummyClient(SecopClient):
     def poll(self):
         messages = super().poll()
         msg = self.graphpoll()
@@ -171,8 +173,9 @@ class SecopDummyClient(SecopClient, DummyGraph):
         return messages
 
 
-class SecopDummyInstrument(SecopInstrument):
-
-    def new_client(self):
-        return self.register(SecopDummyClient(self))
+class DummyHistory:
+    def __init__(self, stream):
+        self.stream = stream
 
+    def get_streams(self, instrument=None, **kwds):
+        return {self.stream: {'device': 'dummy'}}