diff --git a/grpc_robot/services/service.py b/grpc_robot/services/service.py
new file mode 100644
index 0000000..da799c0
--- /dev/null
+++ b/grpc_robot/services/service.py
@@ -0,0 +1,254 @@
+# Copyright 2020-present Open Networking Foundation
+# Original copyright 2020-present ADTRAN, Inc.
+#
+# 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
+import grpc
+from grpc import _channel, ChannelConnectivity
+from decorator import decorator
+
+from ..tools.protobuf_to_dict import protobuf_to_dict, dict_to_protobuf
+from ..tools.robot_tools import Collections
+from google.protobuf import empty_pb2
+
+
+# decorator to check if connection is open
+@decorator
+def is_connected(library_function, *args, **kwargs):
+    try:
+        assert args[0].ctx.grpc_channel is not None
+        grpc.channel_ready_future(args[0].ctx.grpc_channel).result(timeout=10)
+    except (AssertionError, grpc.FutureTimeoutError):
+        raise ConnectionError('not connected to a gRPC channel')
+
+    return library_function(*args, **kwargs)
+
+
+# unfortunately conversation from snake-case to camel-case does not work for all keyword names, so we define a mapping dict
+kw_name_mapping = {
+    'GetHwComponentInfo': 'GetHWComponentInfo',
+    'SetHwComponentInfo': 'SetHWComponentInfo'
+}
+
+one_of_note = """*Note*: Bold dictionary keys are cases of an ONEOF type that is not transmitted in gRPC.\n"""
+named_parameters_note = """*Named parameters*:\n
+- return_enum_integer: <bool> or <string>; Whether or not to return the enum values as integer values rather than their labels. Default: _${FALSE}_ or _false_.\n
+- return_defaults: <bool> or <string>; Whether or not to return the default values. Default: _${FALSE}_ or _false_.\n
+- timeout: <int> or <string>; Number of seconds to wait for the response. Default: The timeout value set by keywords _Connection Open_ and _Connection Parameters Set_."""
+
+
+class Service(object):
+
+    prefix = ''
+
+    def __init__(self, ctx, stub=None):
+        super().__init__()
+        self.ctx = ctx
+
+        try:
+            self.stub = stub(channel=ctx.grpc_channel)
+        except AttributeError:
+            self.stub = None
+
+    def get_next_type_def(self, type_name, module):
+
+        next_type_defs = [d for d in self.ctx.protobuf['data_types'] if d['name'] == type_name]
+
+        if not next_type_defs:
+            return None
+
+        if len(next_type_defs) > 1:
+            next_type_def = [d for d in next_type_defs if d['module'] == module]
+
+            if next_type_def:
+                return next_type_def[0]
+
+            else:
+                return next_type_defs[0]
+
+        else:
+            return next_type_defs[0]
+
+    def lookup_type_def(self, _type_def, _indent='', _lookup_table=None, enum_indent=''):
+
+        _lookup_table = _lookup_table or []
+
+        if _type_def['name'] in _lookup_table:
+            return '< recursive type: ' + _type_def['name'] + ' >'
+        else:
+            _lookup_table.append(_type_def['name'])
+
+        if _type_def['type'] == 'message':
+
+            doc_string = '{    # type: %s\n' % _type_def['name']
+            _indent += '  '
+
+            for field in _type_def['fields']:
+                if field.get('is_choice', False):
+                    doc_string += self.get_field_doc(field, _indent, _lookup_table[:], _type_def['module'], field['name'])
+                else:
+                    doc_string += "%s'%s': %s\n" % (_indent, field['name'], self.get_field_doc(field, _indent, _lookup_table[:], _type_def['module']))
+
+            return doc_string + _indent[:-2] + '}'
+
+        if _type_def['type'] == 'enum':
+
+            try:
+                k_len = 0
+                for k, v in _type_def['values'].items():
+                    k_len = max(len(k), k_len)
+                enum = (' |\n %s%s' % (_indent, enum_indent)).join(['%s%s - %s' % ((k_len - len(k)) * ' ', k, v) for k, v in _type_def['values'].items()])
+
+            except AttributeError:
+                enum = ' | '.join(_type_def['values'])
+
+            return '< %s >' % enum
+
+        return ''
+
+    def get_field_doc(self, _type_def, _indent, _lookup_table, module, choice_name=''):
+
+        doc_string = ''
+
+        _indent = (_indent + '  ') if _type_def.get('repeated', False) else _indent
+
+        if _type_def.get('is_choice', False):
+            for case in _type_def['cases']:
+                # doc_string += "%s'*%s*' (ONEOF _%s_): %s\n" % (_indent, case['name'], choice_name, self.get_field_doc(case, _indent, _lookup_table[:], module))
+                doc_string += "%s'_ONEOF %s_: *%s*': %s\n" % (_indent, choice_name, case['name'], self.get_field_doc(case, _indent, _lookup_table[:], module))
+
+        elif _type_def.get('lookup', False):
+            try:
+                next_type_def = self.get_next_type_def(_type_def['type'], module=module)
+                if next_type_def is not None:
+                    doc_string += self.lookup_type_def(next_type_def, _indent, _lookup_table, (len(_type_def['name']) + 5) * ' ')
+                else:
+                    doc_string += "<%s>," % _type_def['type']
+
+            except KeyError:
+                doc_string += _type_def['type']
+        else:
+            doc_string += "<%s>," % _type_def['type']
+
+        if _type_def.get('repeated', False):
+            doc_string = '[    # list of:\n' + _indent + doc_string + '\n' + _indent[:-2] + ']'
+
+        return doc_string
+
+    def get_rpc_documentation(self, type_def, module):
+
+        indent = '  ' if type_def['is_stream'] else ''
+
+        if type_def['lookup']:
+            next_type_def = self.get_next_type_def(type_def['type'], module)
+            if next_type_def is not None:
+                doc_string = self.lookup_type_def(next_type_def, indent)
+            else:
+                doc_string = type_def['type'] + '\n'
+        else:
+            doc_string = type_def['type'] + '\n'
+
+        if type_def['is_stream']:
+            return '[    # list of:\n' + indent + doc_string + '\n]'
+        else:
+            return doc_string
+
+    def get_documentation(self, keyword_name):
+
+        keyword_name = Collections.to_camel_case(keyword_name.replace(self.prefix, ''), True)
+        keyword_name = kw_name_mapping.get(keyword_name, keyword_name)
+
+        try:
+            service = Collections.list_get_dict_by_value(self.ctx.protobuf.get('services', []), 'name', self.__class__.__name__)
+        except KeyError:
+            return 'no documentation available'
+
+        rpc = Collections.list_get_dict_by_value(service.get('rpcs', []), 'name', keyword_name)
+
+        doc_string = 'RPC _%s_ from _%s_.\n' % (rpc['name'], service['name'])
+        doc_string += '\n\n*Parameters*:\n'
+
+        for attr, attr_str in [('request', '- param_dict'), ('named_params', None), ('response', '*Return*')]:
+
+            if rpc.get(attr) is not None:
+                rpc_doc = '\n'.join(['| %s' % line for line in self.get_rpc_documentation(rpc.get(attr), service['module']).splitlines()])
+
+                if rpc_doc == '| google.protobuf.Empty':
+                    doc_string += '_none_\n\n'
+                    continue
+
+                doc_string += '\n%s:\n' % attr_str if '_ONEOF' not in rpc_doc else '\n%s: %s\n' % (attr_str, one_of_note)
+                doc_string += rpc_doc + '\n'
+
+            elif attr == 'named_params':
+                doc_string += named_parameters_note
+
+        return doc_string
+
+    @staticmethod
+    def to_protobuf(type_def, param_dict):
+        try:
+            return dict_to_protobuf(type_def or empty_pb2.Empty, param_dict or {})
+        except Exception as e:
+            raise ValueError('parameter dictionary does not match the ProtoBuf type definition: %s' % e)
+
+    def _process_response(self, response, index=None, **kwargs):
+
+        debug_text = 'RESPONSE' if index is None else 'RESPONSE-NEXT  ' if index else 'RESPONSE-STREAM'
+
+        return_enum_integer = bool(str(kwargs.get('return_enum_integer', False)).lower() == 'true')
+        return_defaults = bool(str(kwargs.get('return_defaults', False)).lower() == 'true')
+
+        self.ctx.logger.debug('%s : data=%s' % (debug_text, response))
+        _response = protobuf_to_dict(response, use_enum_labels=not return_enum_integer, including_default_value_fields=return_defaults)
+
+        return _response
+
+    def _grpc_helper(self, func, arg_type=None, param_dict=None, **kwargs):
+
+        def generate_stream(arg, data_list):
+
+            for idx, data in enumerate(data_list):
+                _protobuf = self.to_protobuf(arg, data)
+                debug_text = 'REQUEST-NEXT  :' if idx else 'REQUEST-STREAM : method=%s;' % func._method.decode()
+                self.ctx.logger.debug('%s data=%s' % (debug_text, _protobuf))
+                yield _protobuf
+
+        if isinstance(param_dict, list):
+            response = func(generate_stream(arg_type, param_dict), timeout=int(kwargs.get('timeout') or self.ctx.timeout))
+        else:
+            protobuf = self.to_protobuf(arg_type, param_dict)
+            self.ctx.logger.debug('REQUEST : method=%s; data=%s' % (func._method.decode(), protobuf))
+            response = func(protobuf, timeout=int(kwargs.get('timeout') or self.ctx.timeout))
+
+        try:
+
+            # streamed response is of type <grpc._channel._MultiThreadedRendezvous> and must be handle as list
+            if isinstance(response, _channel._MultiThreadedRendezvous):
+
+                return_list = []
+                for idx, list_item in enumerate(response):
+                    return_list.append(self._process_response(list_item, index=idx, **kwargs))
+
+                return return_list
+
+            else:
+
+                return self._process_response(response, **kwargs)
+
+        except grpc.RpcError as e:
+            if e.code().name == 'DEADLINE_EXCEEDED':
+                self.ctx.logger.error('TimeoutError (%ss): %s' % (kwargs.get('timeout') or self.ctx.timeout, e))
+                raise TimeoutError('no response within %s seconds' % (kwargs.get('timeout') or self.ctx.timeout))
+            else:
+                self.ctx.logger.error(e)
+                raise e
+