This commit consists of:
1) Add session management to netconf
2) Modularize the rpc call
3) Improve the error handling
4) Small bug fixes

Change-Id: I023edb76e3743b633ac87be4967d656e09e2b970
diff --git a/netconf/nc_rpc/base/get_config.py b/netconf/nc_rpc/base/get_config.py
new file mode 100644
index 0000000..dffe0d6
--- /dev/null
+++ b/netconf/nc_rpc/base/get_config.py
@@ -0,0 +1,69 @@
+#!/usr/bin/env python
+#
+# Copyright 2016 the original author or authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+from lxml import etree
+import structlog
+from netconf.nc_rpc.rpc import Rpc
+import netconf.nc_common.error as ncerror
+from netconf.constants import Constants as C
+from netconf.utils import elm
+from netconf import NSMAP
+
+log = structlog.get_logger()
+
+class GetConfig(Rpc):
+
+	def __init__(self, rpc_request, rpc_method, session):
+		super(GetConfig, self).__init__(rpc_request, rpc_method, session)
+		self._validate_parameters()
+
+	def execute(self):
+		log.info('get-config-request', session=self.session.session_id)
+		if self.rpc_response.is_error:
+			return self.rpc_response
+
+	def _validate_parameters(self):
+		log.info('validate-parameters', session=self.session.session_id)
+
+		self.params = self.rpc_method.getchildren()
+		paramslen = len(self.params)
+		# Verify that the source parameter is present
+		if paramslen > 2:
+			# TODO: need to specify all elements not known
+			self.rpc_response.is_error = True
+			self.rpc_response.node = ncerror.BadMsg(self.rpc_request)
+			return
+
+		self.source_param = self.rpc_method.find(C.NC_SOURCE, namespaces=NSMAP)
+		if self.source_param is None:
+			self.rpc_response.is_error = True
+			self.rpc_response.node = ncerror.MissingElement(
+				self.rpc_request, elm(C.NC_SOURCE))
+			return
+
+		self.filter_param = None
+		if paramslen == 2:
+			self.filter_param = self.rpc_method.find(C.NC_FILTER,
+												  namespaces=NSMAP)
+			if self.filter_param is None:
+				unknown_elm = self.params[0] if self.params[0] != \
+												self.source_param else \
+												self.params[1]
+				self.rpc_response.is_error = True
+				self.rpc_response.node = ncerror.UnknownElement(
+					self.rpc_request, unknown_elm)
+
+		self.params = [self.source_param, self.filter_param]