#9733: Extend RemoteMonitor to send data as application/json

keras/callbacks.py

@@ -547,25 +547,31 @@ class RemoteMonitor(Callback):
     Events are sent to `root + '/publish/epoch/end/'` by default. Calls are
     HTTP POST, with a `data` argument which is a
     JSON-encoded dictionary of event data.
+    If send_as_json is set to True, the content type of the request will be application/json.
+    Otherwise the serialized JSON will be send within a form
 
     # Arguments
         root: String; root url of the target server.
         path: String; path relative to `root` to which the events will be sent.
-        field: String; JSON field under which the data will be stored.
+        field: String; JSON field under which the data will be stored. The field is used only if the payload is sent
+        within a form (i.e. send_as_json is set to False).
         headers: Dictionary; optional custom HTTP headers.
+        send_as_json: Boolean; whether the request should be send as application/json.
     """
 
     def __init__(self,
                  root='http://localhost:9000',
                  path='/publish/epoch/end/',
                  field='data',
-                 headers=None):
+                 headers=None,
+                 send_as_json=False):
         super(RemoteMonitor, self).__init__()
 
         self.root = root
         self.path = path
         self.field = field
         self.headers = headers
+        self.send_as_json = send_as_json
 
     def on_epoch_end(self, epoch, logs=None):
         if requests is None:
@@ -580,9 +586,12 @@ def on_epoch_end(self, epoch, logs=None):
             else:
                 send[k] = v
         try:
-            requests.post(self.root + self.path,
-                          {self.field: json.dumps(send)},
-                          headers=self.headers)
+            if self.send_as_json:
+                requests.post(self.root + self.path, json=send, headers=self.headers)
+            else:
+                requests.post(self.root + self.path,
+                              {self.field: json.dumps(send)},
+                              headers=self.headers)
         except requests.exceptions.RequestException:
             warnings.warn('Warning: could not reach RemoteMonitor '
                           'root server at ' + str(self.root))

tests/keras/test_callbacks.py

@@ -806,5 +806,27 @@ def tests_RemoteMonitor():
                   validation_data=(X_test, y_test), callbacks=cbks, epochs=1)
 
 
+@keras_test
+def tests_RemoteMonitorWithJsonPayload():
+    (X_train, y_train), (X_test, y_test) = get_test_data(num_train=train_samples,
+                                                         num_test=test_samples,
+                                                         input_shape=(input_dim,),
+                                                         classification=True,
+                                                         num_classes=num_classes)
+    y_test = np_utils.to_categorical(y_test)
+    y_train = np_utils.to_categorical(y_train)
+    model = Sequential()
+    model.add(Dense(num_hidden, input_dim=input_dim, activation='relu'))
+    model.add(Dense(num_classes, activation='softmax'))
+    model.compile(loss='categorical_crossentropy',
+                  optimizer='rmsprop',
+                  metrics=['accuracy'])
+    cbks = [callbacks.RemoteMonitor(send_as_json=True)]
+
+    with patch('requests.post'):
+        model.fit(X_train, y_train, batch_size=batch_size,
+                  validation_data=(X_test, y_test), callbacks=cbks, epochs=1)
+
+
 if __name__ == '__main__':
     pytest.main([__file__])