diff --git a/README.md b/README.md
index 72f1506a..140bb6fe 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,6 @@
+# Python Tools for Visual Studio debug server
 
-# Contributing
+## Contributing
 
 This project welcomes contributions and suggestions.  Most contributions require you to agree to a
 Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us
diff --git a/ptvsd/__init__.py b/ptvsd/__init__.py
new file mode 100644
index 00000000..332469b8
--- /dev/null
+++ b/ptvsd/__init__.py
@@ -0,0 +1,5 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See LICENSE in the project root for license information.
+
+__author__ = "Microsoft Corporation <ptvshelp@microsoft.com>"
+__version__ = "4.0.0a1"
diff --git a/ptvsd/__main__.py b/ptvsd/__main__.py
new file mode 100644
index 00000000..b1a6e4fb
--- /dev/null
+++ b/ptvsd/__main__.py
@@ -0,0 +1,10 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See LICENSE in the project root for license information.
+
+__author__ = "Microsoft Corporation <ptvshelp@microsoft.com>"
+__version__ = "4.0.0a1"
+
+if __name__ == '__main__':
+    import ptvsd.wrapper
+    import pydevd
+    pydevd.main()
diff --git a/ptvsd/debugger.py b/ptvsd/debugger.py
new file mode 100644
index 00000000..9b0f4175
--- /dev/null
+++ b/ptvsd/debugger.py
@@ -0,0 +1,14 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See LICENSE in the project root for license information.
+
+__author__ = "Microsoft Corporation <ptvshelp@microsoft.com>"
+__version__ = "4.0.0a1"
+
+DONT_DEBUG = []
+
+def debug(filename, port_num, debug_id, debug_options, run_as):
+    import sys
+    import ptvsd.wrapper 
+    import pydevd
+    sys.argv[1:0] = ['--port', str(port_num), '--client', '127.0.0.1', '--file', filename]
+    pydevd.main()
diff --git a/ptvsd/futures.py b/ptvsd/futures.py
new file mode 100644
index 00000000..249ce17b
--- /dev/null
+++ b/ptvsd/futures.py
@@ -0,0 +1,136 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See LICENSE in the project root for license information.
+
+from __future__ import print_function, with_statement, absolute_import
+
+__author__ = "Microsoft Corporation <ptvshelp@microsoft.com>"
+__version__ = "4.0.0a1"
+
+import sys
+import threading
+from ptvsd.reraise import reraise
+
+
+class Future(object):
+    def __init__(self, loop):
+        self._lock = threading.Lock()
+        self._loop = loop
+        self._done = False
+        self._observed = False
+        self._done_callbacks = []
+
+    def __del__(self):
+        with self._lock:
+            if self._done and self._exc_info and not self._observed:
+                print('Unobserved exception in a Future:', file=sys.__stderr__)
+                traceback.print_exception(self._exc_info[0], self._exc_info[1], self._exc_info[2], file=sys.__stderr__)
+
+    def result(self):
+        with self._lock:
+            self._observed = True
+            if self._exc_info:
+                reraise(self._exc_info)
+            return self._result
+
+    def exc_info(self):
+        with self._lock:
+            self._observed = True
+            return self._exc_info
+
+    def set_result(self, result):
+        with self._lock:
+            self._result = result
+            self._exc_info = None
+            self._done = True
+            callbacks = list(self._done_callbacks)
+        def invoke_callbacks():
+            for cb in callbacks:
+                cb(self)
+        self._loop.call_soon(invoke_callbacks)
+
+    def set_exc_info(self, exc_info):
+        with self._lock:
+            self._exc_info = exc_info
+            self._done = True
+            callbacks = list(self._done_callbacks)
+        def invoke_callbacks():
+            for cb in callbacks:
+                cb(self)
+        self._loop.call_soon(invoke_callbacks)
+
+    def add_done_callback(self, callback):
+        with self._lock:
+            done = self._done
+            self._done_callbacks.append(callback)
+        if done:
+            callback(self)
+
+    def remove_done_callback(self, callback):
+        with self._lock:
+            self._done_callbacks.remove(callback)
+
+       
+class EventLoop(object):
+    def __init__(self):
+        self._queue = []
+        self._lock = threading.Lock()
+        self._event = threading.Event()
+        self._event.set()
+
+    def create_future(self):
+        return Future(self)
+
+    def run_forever(self):
+        while True:
+            self._event.wait()
+            with self._lock:
+                queue = self._queue
+                self._queue = []
+                self._event.clear()
+            for (f, args) in queue:
+                f(*args)
+        
+    def call_soon(self, f, *args):
+        with self._lock:
+            self._queue.append((f, args))
+            self._event.set()
+
+    def call_soon_threadsafe(self, f, *args):
+        return self.call_soon(f, *args)
+
+
+class Result(object):
+    __slots__ = ['value']
+    def __init__(self, value):
+        self.value = value
+
+        
+def async(f):
+    def g(self, loop, *args, **kwargs):
+        it = f(self, *args, **kwargs)
+        result = Future(loop)
+        if it is None:
+            result.set_result(None)
+            return result
+        def callback(fut):
+            try:
+                if fut is None:
+                    x = next(it)
+                else:
+                    exc_info = fut.exc_info()
+                    if exc_info:
+                        x = it.throw(exc_info[0], exc_info[1], exc_info[2])
+                    else:
+                        x = it.send(fut.result())
+            except StopIteration:
+                result.set_result(None)
+            except BaseException as ex:
+                result.set_exc_info(sys.exc_info())
+            else:
+                if isinstance(x, Result):
+                    result.set_result(x.value)
+                else:
+                    x.add_done_callback(callback)
+        callback(None)
+        return result
+    return g
diff --git a/ptvsd/ipcjson.py b/ptvsd/ipcjson.py
new file mode 100644
index 00000000..b42b0867
--- /dev/null
+++ b/ptvsd/ipcjson.py
@@ -0,0 +1,294 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See LICENSE in the project root for license information.
+
+from __future__ import print_function, with_statement, absolute_import
+
+__author__ = "Microsoft Corporation <ptvshelp@microsoft.com>"
+__version__ = "4.0.0a1"
+
+# This module MUST NOT import threading in global scope. This is because in a direct (non-ptvsd)
+# attach scenario, it is loaded on the injected debugger attach thread, and if threading module
+# hasn't been loaded already, it will assume that the thread on which it is being loaded is the
+# main thread. This will cause issues when the thread goes away after attach completes.
+
+import json
+import os.path
+import itertools
+import socket
+import sys
+import traceback
+
+_TRACE = None
+
+if sys.version_info[0] >= 3:
+    from encodings import ascii
+    def to_bytes(cmd_str):
+        return ascii.Codec.encode(cmd_str)[0]
+else:
+    def to_bytes(cmd_str):
+        return cmd_str
+
+def _str_or_call(m):
+    try:
+        callable = m.__call__
+    except AttributeError:
+        return str(m)
+    else:
+        return str(callable())
+
+def _trace(*msg):
+    if _TRACE:
+        _TRACE(''.join(_str_or_call(m) for m in msg) + '\n')
+
+
+SKIP_TB_PREFIXES = [
+    os.path.normcase(os.path.dirname(os.path.abspath(__file__)))
+]
+
+class InvalidHeaderError(Exception): pass
+
+class InvalidContentError(Exception): pass
+
+class SocketIO(object):
+    def __init__(self, *args, **kwargs):
+        super(SocketIO, self).__init__(*args, **kwargs)
+        self.__buffer = to_bytes('')
+        self.__port = kwargs.get('port')
+        self.__socket = kwargs.get('socket')
+        self.__own_socket = kwargs.get('own_socket', True)
+        self.__logfile = kwargs.get('logfile')
+        if self.__socket is None and self.__port is None:
+            raise ValueError("A 'port' or a 'socket' must be passed to SocketIO initializer as a keyword argument.")
+        if self.__socket is None:
+             self.__socket = socket.create_connection(('127.0.0.1', self.__port))
+
+    def _send(self, **payload):
+        content = json.dumps(payload).encode('utf-8')
+        headers = ('Content-Length: %d\r\n\r\n' % (len(content), )).encode('ascii')
+        if self.__logfile is not None:
+            self.__logfile.write(content)
+            self.__logfile.write('\n'.encode('utf-8'))
+            self.__logfile.flush()
+        self.__socket.send(headers)
+        self.__socket.send(content)
+
+    def _buffered_read_line_as_ascii(self):
+        '''
+        Reads bytes until it encounters newline chars, and returns the bytes
+        ascii decoded, newline chars are excluded from the return value.
+        Blocks until: newline chars are read OR socket is closed.
+        '''
+        newline = '\r\n'.encode('ascii')
+        while newline not in self.__buffer:
+            temp = self.__socket.recv(1024)
+            if not temp:
+                break
+            self.__buffer += temp
+
+        if not self.__buffer:
+            return None
+
+        try:
+            index = self.__buffer.index(newline)
+        except ValueError:
+            raise InvalidHeaderError('Header line not terminated')
+
+        line = self.__buffer[:index]
+        self.__buffer = self.__buffer[index+len(newline):]
+        return line.decode('ascii', 'replace')
+
+    def _buffered_read_as_utf8(self, length):
+        while len(self.__buffer) < length:
+            temp = self.__socket.recv(1024)
+            if not temp:
+                break
+            self.__buffer += temp
+
+        if len(self.__buffer) < length:
+            raise InvalidContentError('Expected to read {0} bytes of content, but only read {1} bytes.'.format(length, len(self.__buffer)))
+
+        content = self.__buffer[:length]
+        self.__buffer = self.__buffer[length:]
+        return content.decode('utf-8', 'replace')
+
+    def _wait_for_message(self):
+        # base protocol defined at https://github.com/Microsoft/language-server-protocol/blob/master/protocol.md#base-protocol
+        # read all headers, ascii encoded separated by '\r\n'
+        # end of headers is indicated by an empty line
+        headers = {}
+        line = self._buffered_read_line_as_ascii()
+        while line:
+            parts = line.split(':')
+            if len(parts) == 2:
+                headers[parts[0]] = parts[1]
+            else:
+                raise InvalidHeaderError("Malformed header, expected 'name: value'\n{0}".format(line))
+            line = self._buffered_read_line_as_ascii()
+
+        # end of stream
+        if not line and not headers:
+            return
+
+        # validate headers
+        try:
+            length_text = headers['Content-Length']
+            try:
+                length = int(length_text)
+            except ValueError:
+                raise InvalidHeaderError("Invalid Content-Length: {0}".format(length_text))
+        except NameError:
+            raise InvalidHeaderError('Content-Length not specified in headers')
+        except KeyError:
+            raise InvalidHeaderError('Content-Length not specified in headers')
+
+        if length < 0 or length > 2147483647:
+            raise InvalidHeaderError("Invalid Content-Length: {0}".format(length))
+
+        # read content, utf-8 encoded
+        content = self._buffered_read_as_utf8(length)
+        try:
+            msg = json.loads(content)
+            self._receive_message(msg)
+        except ValueError:
+            raise InvalidContentError('Error deserializing message content.')
+        except json.decoder.JSONDecodeError:
+            raise InvalidContentError('Error deserializing message content.')
+
+    def _close(self):
+        if self.__own_socket:
+            self.__socket.close()
+
+'''
+class StandardIO(object):
+    def __init__(self, stdin, stdout, *args, **kwargs):
+        super(StandardIO, self).__init__(*args, **kwargs)
+        try:
+            self.__stdin = stdin.buffer
+            self.__stdout = stdout.buffer
+        except AttributeError:
+            self.__stdin = stdin
+            self.__stdout = stdout
+
+    def _send(self, **payload):
+        data = json.dumps(payload).encode('utf-8') + NEWLINE_BYTES
+        self.__stdout.write(data)
+        self.__stdout.flush()
+
+    def _wait_for_message(self):
+        msg = json.loads(self.__stdin.readline().decode('utf-8', 'replace').rstrip())
+        self._receive_message(msg)
+
+    def _close(self):
+        pass
+'''
+
+class IpcChannel(object):
+    def __init__(self, *args, **kwargs):
+        # This class is meant to be last in the list of base classes
+        # Don't call super because object's __init__ doesn't take arguments
+        try:
+            import thread
+        except:
+            import _thread as thread
+        self.__seq = itertools.count()
+        self.__exit = False
+        self.__lock = thread.allocate_lock()
+        self.__message = []
+        self.__exit_on_unknown_command = True
+
+    def close(self):
+        self._close()
+
+    def send_event(self, _name, **kwargs):
+        with self.__lock:
+            self._send(
+                type='event',
+                seq=next(self.__seq),
+                event=_name,
+                body=kwargs,
+            )
+
+    def send_response(self, request, success=True, message=None, **kwargs):
+        with self.__lock:
+            self._send(
+                type='response',
+                seq=next(self.__seq),
+                request_seq=int(request.get('seq', 0)),
+                success=success,
+                command=request.get('command', ''),
+                message=message or '',
+                body=kwargs,
+            )
+
+    def set_exit(self):
+        self.__exit = True
+
+    def process_messages(self):
+        while True:
+            if self.process_one_message():
+                return
+
+    def process_one_message(self):
+        try:
+            msg = self.__message.pop(0)
+        except IndexError:
+            self._wait_for_message()
+            try:
+                msg = self.__message.pop(0)
+            except IndexError:
+                return self.__exit
+
+        _trace('Received ', msg)
+
+        try:
+            if msg['type'] == 'request':
+                self.on_request(msg)
+            elif msg['type'] == 'response':
+                self.on_response(msg)
+            elif msg['type'] == 'event':
+                self.on_event(msg)
+            else:
+                self.on_invalid_request(msg, {})
+        except AssertionError:
+            raise
+        except Exception:
+            _trace('Error ', traceback.format_exc)
+            traceback.print_exc()
+
+        _trace('self.__exit is ', self.__exit)
+        return self.__exit
+
+    def on_request(self, request):
+        assert request.get('type', '') == 'request', "Only handle 'request' messages in on_request"
+
+        cmd = request.get('command', '')
+        args = request.get('arguments', {})
+        target = getattr(self, 'on_' + cmd, self.on_invalid_request)
+        try:
+            _trace('Calling ', repr(target))
+            target(request, args)
+        except AssertionError:
+            raise
+        except Exception:
+            self.send_response(
+                request,
+                success=False,
+                message=traceback.format_exc(),
+            )
+
+    def on_response(self, msg):
+        # this class is only used for server side only for now
+        raise NotImplementedError
+
+    def on_event(self, msg):
+        # this class is only used for server side only for now
+        raise NotImplementedError
+
+    def on_invalid_request(self, request, args):
+        self.send_response(request, success=False, message='Unknown command')
+        if self.__exit_on_unknown_command:
+            self.__exit = True
+
+    def _receive_message(self, message):
+        with self.__lock:
+            self.__message.append(message)
diff --git a/ptvsd/reraise.py b/ptvsd/reraise.py
new file mode 100644
index 00000000..acce8865
--- /dev/null
+++ b/ptvsd/reraise.py
@@ -0,0 +1,14 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See LICENSE in the project root for license information.
+
+from __future__ import print_function, with_statement, absolute_import
+
+__author__ = "Microsoft Corporation <ptvshelp@microsoft.com>"
+__version__ = "4.0.0a1"
+
+import sys
+
+if sys.version_info >= (3,):
+    from ptvsd.reraise3 import reraise
+else:
+    from ptvsd.reraise2 import reraise
diff --git a/ptvsd/reraise2.py b/ptvsd/reraise2.py
new file mode 100644
index 00000000..d0dfb7cc
--- /dev/null
+++ b/ptvsd/reraise2.py
@@ -0,0 +1,10 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See LICENSE in the project root for license information.
+
+from __future__ import print_function, with_statement, absolute_import
+
+__author__ = "Microsoft Corporation <ptvshelp@microsoft.com>"
+__version__ = "4.0.0a1"
+
+def reraise(exc_info):
+    raise exc_info[0], exc_info[1], exc_info[2]
diff --git a/ptvsd/reraise3.py b/ptvsd/reraise3.py
new file mode 100644
index 00000000..58126c24
--- /dev/null
+++ b/ptvsd/reraise3.py
@@ -0,0 +1,10 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See LICENSE in the project root for license information.
+
+from __future__ import print_function, with_statement, absolute_import
+
+__author__ = "Microsoft Corporation <ptvshelp@microsoft.com>"
+__version__ = "4.0.0a1"
+
+def reraise(exc_info):
+    raise exc_info[1].with_traceback(exc_info[2])
diff --git a/ptvsd/wrapper.py b/ptvsd/wrapper.py
new file mode 100644
index 00000000..f5bc2cd8
--- /dev/null
+++ b/ptvsd/wrapper.py
@@ -0,0 +1,541 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See LICENSE in the project root for license information.
+
+from __future__ import print_function, with_statement, absolute_import
+
+__author__ = "Microsoft Corporation <ptvshelp@microsoft.com>"
+__version__ = "4.0.0a1"
+
+import io
+import os
+import socket
+import sys
+import time
+import threading
+import traceback
+import untangle 
+
+try:
+    from urllib import quote_plus, unquote, unquote_plus
+except:
+    from urllib.parse import quote_plus, unquote, unquote_plus
+
+import _pydevd_bundle.pydevd_comm as pydevd_comm
+from _pydevd_bundle.pydevd_comm import pydevd_log
+
+import ptvsd.ipcjson as ipcjson
+import ptvsd.futures as futures
+
+
+#def ipcjson_trace(s):
+#    print(s)
+#ipcjson._TRACE = ipcjson_trace
+
+
+# Generates VSCode entity IDs, and maps them to corresponding pydevd entity IDs.
+#
+# For VSCode, IDs are always integers, and uniquely identify the entity among all other
+# entities of the same type - e.g. all frames across all threads have unique IDs.
+#
+# For pydevd, IDs can be integer or strings, and are usually specific to some scope -
+# for example, a frame ID is only unique within a given thread. To produce a truly unique
+# ID, the IDs of all the outer scopes have to be combined into a tuple. Thus, for example,
+# a pydevd frame ID is (thread_id, frame_id).
+#
+# Variables (evaluation results) technically don't have IDs in pydevd, as it doesn't have
+# evaluation persistence. However, for a given frame, any child can be identified by the
+# path one needs to walk from the root of the frame to get to that child - and that path,
+# represented as a sequence of its consituent components, is used by pydevd commands to
+# identify the variable. So we use the tuple representation of the same as its pydevd ID.
+# For example, for something like foo[1].bar, its ID is:
+#   (thread_id, frame_id, 'FRAME', 'foo', 1, 'bar')
+#
+# For pydevd breakpoints, the ID has to be specified by the caller when creating, so we
+# can just reuse the ID that was generated for VSC. However, when referencing the pydevd
+# breakpoint later (e.g. to remove it), its ID must be specified together with path to
+# file in which that breakpoint is set - i.e. pydevd treats those IDs as scoped to a file.
+# So, even though breakpoint IDs are unique across files, use (path, bp_id) as pydevd ID.
+class IDMap(object):
+    def __init__(self):
+        self._vscode_to_pydevd = {}
+        self._pydevd_to_vscode = {}
+        self._next_id = 1
+        self._lock = threading.Lock()
+
+    def pairs(self):
+        with self._lock:
+            return list(self._pydevd_to_vscode.items())
+    
+    def add(self, pydevd_id):
+        with self._lock:
+            vscode_id = self._next_id
+            if callable(pydevd_id):
+                pydevd_id = pydevd_id(vscode_id)
+            self._next_id += 1
+            self._vscode_to_pydevd[vscode_id] = pydevd_id
+            self._pydevd_to_vscode[pydevd_id] = vscode_id
+        return vscode_id
+
+    def remove(self, pydevd_id=None, vscode_id=None):
+        with self._lock:
+            if pydevd_id is None:
+                pydevd_id = self._vscode_to_pydevd[vscode_id]
+            elif vscode_id is None:
+                vscode_id = self._pydevd_to_vscode[pydevd_id]
+            del self._vscode_to_pydevd[vscode_id]
+            del self._pydevd_to_vscode[pydevd_id]
+    
+    def to_pydevd(self, vscode_id):
+        return self._vscode_to_pydevd[vscode_id]
+
+    def to_vscode(self, pydevd_id, autogen=True):
+        try:
+            return self._pydevd_to_vscode[pydevd_id]
+        except KeyError:
+            if autogen:
+                return self.add(pydevd_id)
+            else:
+                raise
+
+    def pydevd_ids(self):
+        with self._lock:
+            ids = list(self._pydevd_to_vscode.keys())
+        return ids
+
+    def vscode_ids(self):
+        with self._lock:
+            ids = list(self._vscode_to_pydevd.keys())
+        return ids
+
+class ExceptionInfo(object):
+    def __init__(self, name, description):
+        self.name = name
+        self.description = description
+
+# A dummy socket-like object that is given to pydevd in lieu of the real thing.
+# It parses pydevd messages and redirects them to the provided handler callback.
+# It also provides an interface to send notifications and requests to pydevd;
+# for requests, the reply can be asynchronously awaited.
+class PydevdSocket(object):
+    def __init__(self, event_handler):
+        #self.log = open('pydevd.log', 'w')
+        self.event_handler = event_handler
+        self.lock = threading.Lock()
+        self.seq = 1
+        self.pipe_r, self.pipe_w = os.pipe()
+        self.requests = {}
+
+    def close(self):
+        pass
+
+    def shutdown(self, mode):
+        pass
+
+    def recv(self, count):
+        data = os.read(self.pipe_r, count)
+        #self.log.write('>>>[' + data.decode('utf8') + ']\n\n')
+        #self.log.flush()
+        return data
+
+    def send(self, data):
+        result = len(data)
+        data = unquote(data.decode('utf8'))
+        #self.log.write('<<<[' + data + ']\n\n')
+        #self.log.flush()
+        cmd_id, seq, args = data.split('\t', 2)
+        cmd_id = int(cmd_id)
+        seq = int(seq)
+        with self.lock:
+            loop, fut = self.requests.pop(seq, (None, None))
+        if fut is None:
+            self.event_handler(cmd_id, seq, args)
+        else:
+            loop.call_soon_threadsafe(fut.set_result, (cmd_id, seq, args))
+        return result
+
+    def make_packet(self, cmd_id, args):
+        with self.lock:
+            seq = self.seq
+            self.seq += 1
+        s = "%s\t%s\t%s\n" % (cmd_id, seq, args)
+        return seq, s
+
+    def pydevd_notify(self, cmd_id, args):
+        seq, s = self.make_packet(cmd_id, args)
+        os.write(self.pipe_w, s.encode('utf8'))
+
+    def pydevd_request(self, loop, cmd_id, args):
+        seq, s = self.make_packet(cmd_id, args)
+        fut = loop.create_future()
+        with self.lock:
+            self.requests[seq] = loop, fut
+            os.write(self.pipe_w, s.encode('utf8'))
+        return fut
+
+# IPC JSON message processor for VSC debugger protocol, mapping it to pydevd protocol.
+class VSCodeMessageProcessor(ipcjson.SocketIO, ipcjson.IpcChannel):
+    def __init__(self, socket, pydevd, logfile=None):
+        super(VSCodeMessageProcessor, self).__init__(socket=socket, own_socket=False, logfile=logfile)
+        self.socket = socket
+        self.pydevd = pydevd
+        self.stack_traces = {}
+        self.stack_traces_lock = threading.Lock()
+        self.active_exceptions = {}
+        self.active_exceptions_lock = threading.Lock()
+        self.thread_map = IDMap()
+        self.frame_map = IDMap()
+        self.var_map = IDMap()
+        self.bp_map = IDMap()
+        self.next_var_ref = 0
+        self.loop = futures.EventLoop()
+        threading.Thread(target = self.loop.run_forever, name = 'ptvsd.EventLoop').start()
+
+    def close(self):
+        if self.socket:
+            self.socket.close()
+
+    def pydevd_notify(self, cmd_id, args):
+        try:
+            return self.pydevd.pydevd_notify(cmd_id, args)
+        except:
+            traceback.print_exc()
+            raise
+
+    def pydevd_request(self, cmd_id, args):
+        return self.pydevd.pydevd_request(self.loop, cmd_id, args)
+
+    # Instances of this class provide decorators to mark methods as handlers for various
+    # pydevd messages - a decorated method is added to the map with the corresponding
+    # message ID, and is looked up there by pydevd event handler below.
+    class EventHandlers(dict):
+        def handler(self, cmd_id):
+            def decorate(f):
+                self[cmd_id] = f
+                return f
+            return decorate
+
+    pydevd_events = EventHandlers()
+
+    def on_pydevd_event(self, cmd_id, seq, args):
+        try:
+            f = self.pydevd_events[cmd_id]
+        except KeyError:
+            raise Exception('Unsupported pydevd command ' + str(cmd_id))
+        return f(self, seq, args)
+
+    def async_handler(m):
+        m = futures.async(m)
+        def f(self, *args, **kwargs):
+            fut = m(self, self.loop, *args, **kwargs)
+            def done(fut):
+                try:
+                    fut.result()
+                except:
+                    traceback.print_exc(file=sys.__stderr__)
+            fut.add_done_callback(done)
+        return f
+
+    @async_handler
+    def on_initialize(self, request, args):
+        yield self.pydevd_request(pydevd_comm.CMD_VERSION, '1.1\tWINDOWS\tID')
+        self.send_response(request,
+            supportsExceptionInfoRequest=True,
+            supportsConfigurationDoneRequest=True,
+            exceptionBreakpointFilters=[
+                {'filter': 'raised', 'label': 'Raised Exceptions'},
+                {'filter': 'uncaught', 'label': 'Uncaught Exceptions'},
+            ]
+        )
+        self.send_event('initialized')
+
+    def on_configurationDone(self, request, args):
+        self.send_response(request)
+
+    def on_disconnect(self, request, args):
+        self.send_response(request)
+
+    @async_handler
+    def on_attach(self, request, args):
+        self.send_response(request)
+        yield self.pydevd_request(pydevd_comm.CMD_RUN, '')
+        self.send_process_event('attach')
+
+    @async_handler
+    def on_launch(self, request, args):
+        self.send_response(request)
+        yield self.pydevd_request(pydevd_comm.CMD_RUN, '')
+        self.send_process_event('launch')
+
+    def send_process_event(self, start_method):
+        evt = {
+            'name': sys.argv[0],
+            'systemProcessId': os.getpid(),
+            'isLocalProcess': True,
+            'startMethod': start_method,
+        }
+        self.send_event('process', **evt)
+
+    @async_handler
+    def on_threads(self, request, args):
+        _, _, args = yield  self.pydevd_request(pydevd_comm.CMD_LIST_THREADS, '')
+        xml = untangle.parse(args).xml
+        try:
+            xthreads = xml.thread
+        except AttributeError:
+            xthreads = []
+
+        threads = []
+        for xthread in xthreads:
+            tid = self.thread_map.to_vscode(xthread['id'])
+            try:
+                name = unquote(xthread['name'])
+            except KeyError:
+                name = None                
+            if not (name and name.startswith('pydevd.')):
+                threads.append({'id': tid, 'name': name})
+            
+        self.send_response(request, threads=threads)
+
+    @async_handler
+    def on_stackTrace(self, request, args):
+        tid = int(args['threadId'])
+        startFrame = int(args['startFrame'])
+        levels = int(args['levels'])
+
+        tid = self.thread_map.to_pydevd(tid)
+        with self.stack_traces_lock:
+            xframes = self.stack_traces[tid]
+        totalFrames = len(xframes)
+
+        if levels == 0:
+            levels = totalFrames
+
+        stackFrames = []
+        for xframe in xframes:
+            if startFrame > 0:
+                startFrame -= 1
+                continue
+            if levels <= 0:
+                break
+            levels -= 1
+            fid = self.frame_map.to_vscode((tid, int(xframe['id'])))
+            name = unquote(xframe['name'])
+            file = unquote(xframe['file'])
+            line = int(xframe['line'])
+            stackFrames.append({'id': fid, 'name': name, 'source': {'path': file}, 'line': line, 'column': 0})
+
+        self.send_response(request, stackFrames=stackFrames, totalFrames=totalFrames)
+
+    @async_handler
+    def on_scopes(self, request, args):
+        vsc_fid = int(args['frameId'])
+        pyd_tid, pyd_fid = self.frame_map.to_pydevd(vsc_fid)
+        pyd_var = (pyd_tid, pyd_fid, 'FRAME')
+        vsc_var = self.var_map.to_vscode(pyd_var)
+        scope = {'name': 'Locals', 'expensive': False, 'variablesReference': vsc_var}
+        self.send_response(request, scopes=[scope])
+
+    @async_handler
+    def on_variables(self, request, args):
+        vsc_var = int(args['variablesReference'])
+        pyd_var = self.var_map.to_pydevd(vsc_var)
+
+        if len(pyd_var) == 3:
+            cmd = pydevd_comm.CMD_GET_FRAME
+        else:
+            cmd = pydevd_comm.CMD_GET_VARIABLE
+
+        _, _, args = yield self.pydevd_request(cmd, '\t'.join(str(s) for s in pyd_var))
+        xml = untangle.parse(args).xml
+        try:
+            xvars = xml.var
+        except AttributeError:
+            xvars = []
+
+        vars = []
+        for xvar in xvars:
+            var = {
+                'name': unquote(xvar['name']),
+                'type': unquote(xvar['type']),
+                'value': unquote(xvar['value']),
+            }
+            if bool(xvar['isContainer']):
+                pyd_child = pyd_var + (var['name'],)
+                var['variablesReference'] = self.var_map.to_vscode(pyd_child)
+            vars.append(var)
+
+        self.send_response(request, variables=vars)
+
+    @async_handler
+    def on_pause(self, request, args):
+        vsc_tid = int(args['threadId'])
+        if vsc_tid == 0: # VS does this to mean "stop all threads":
+            for pyd_tid in self.thread_map.pydevd_ids():
+                self.pydevd_notify(pydevd_comm.CMD_THREAD_SUSPEND, pyd_tid)
+        else:
+            pyd_tid = self.thread_map.to_pydevd(vsc_tid)
+            self.pydevd_notify(pydevd_comm.CMD_THREAD_SUSPEND, pyd_tid)
+        self.send_response(request)
+
+    @async_handler
+    def on_continue(self, request, args):
+        tid = self.thread_map.to_pydevd(int(args['threadId']))
+        self.pydevd_notify(pydevd_comm.CMD_THREAD_RUN, tid)
+        self.send_response(request)
+
+    @async_handler
+    def on_next(self, request, args):
+        tid = self.thread_map.to_pydevd(int(args['threadId']))
+        self.pydevd_notify(pydevd_comm.CMD_STEP_OVER, tid)
+        self.send_response(request)
+
+    @async_handler
+    def on_stepIn(self, request, args):
+        tid = self.thread_map.to_pydevd(int(args['threadId']))
+        self.pydevd_notify(pydevd_comm.CMD_STEP_INTO, tid)
+        self.send_response(request)
+
+    @async_handler
+    def on_stepOut(self, request, args):
+        tid = self.thread_map.to_pydevd(int(args['threadId']))
+        self.pydevd_notify(pydevd_comm.CMD_STEP_RETURN, tid)
+        self.send_response(request)
+
+    @async_handler
+    def on_setBreakpoints(self, request, args):
+        bps = []
+        path = args['source']['path']
+        src_bps = args.get('breakpoints', [])
+
+        # First, we must delete all existing breakpoints in that source.
+        for pyd_bpid, vsc_bpid in self.bp_map.pairs():
+            self.pydevd_notify(pydevd_comm.CMD_REMOVE_BREAK, 'python-line\t%s\t%s' % (path, vsc_bpid))
+            self.bp_map.remove(pyd_bpid, vsc_bpid)
+
+        for src_bp in src_bps:
+            line = src_bp['line']
+            vsc_bpid = self.bp_map.add(lambda vsc_bpid: (path, vsc_bpid))
+            self.pydevd_notify(pydevd_comm.CMD_SET_BREAK, '%s\tpython-line\t%s\t%s\tNone\tNone\tNone' %
+                (vsc_bpid, path, line))
+            bps.append({ 'id': vsc_bpid, 'verified': True, 'line': line })
+
+        self.send_response(request, breakpoints=bps)
+
+    @async_handler
+    def on_setExceptionBreakpoints(self, request, args):
+        self.pydevd_notify(pydevd_comm.CMD_REMOVE_EXCEPTION_BREAK, 'python-BaseException') 
+        filters = args['filters']
+        break_raised = 'raised' in filters
+        break_uncaught = 'uncaught' in filters
+        if break_raised or break_uncaught:
+            self.pydevd_notify(pydevd_comm.CMD_ADD_EXCEPTION_BREAK, 'python-BaseException\t%s\t%s\t%s' % (
+                2 if break_raised else 0, 1 if break_uncaught else 0, 0))
+        self.send_response(request)
+
+    @async_handler
+    def on_exceptionInfo(self, request, args):
+        tid = self.thread_map.to_pydevd(args['threadId'])
+        with self.active_exceptions_lock:
+            exc = self.active_exceptions[tid]
+        self.send_response(request, exceptionId=exc.name, description=exc.description, breakMode='unhandled', details={
+            'typeName': exc.name,
+            'message': exc.description,
+        })            
+
+    @pydevd_events.handler(pydevd_comm.CMD_THREAD_CREATE)
+    def on_pydevd_thread_create(self, seq, args):
+        xml = untangle.parse(args).xml
+        tid = self.thread_map.to_vscode(xml.thread['id'])
+        self.send_event('thread', reason='started', threadId=tid)
+
+    @pydevd_events.handler(pydevd_comm.CMD_THREAD_KILL)
+    def on_pydevd_thread_kill(self, seq, args):
+        try:
+            tid = self.thread_map.to_vscode(args, autogen=False)
+        except KeyError:
+            pass
+        else:
+            self.send_event('thread', reason='exited', threadId=tid)
+
+    @pydevd_events.handler(pydevd_comm.CMD_THREAD_SUSPEND)
+    def on_pydevd_thread_suspend(self, seq, args):
+        xml = untangle.parse(args).xml
+        tid = xml.thread['id']
+        reason = int(xml.thread['stop_reason'])
+        print(reason, file=open('reason.log', 'a'))
+        if reason in (pydevd_comm.CMD_STEP_INTO, pydevd_comm.CMD_STEP_OVER, pydevd_comm.CMD_STEP_RETURN):
+            reason = 'step'
+        elif reason == pydevd_comm.CMD_STEP_CAUGHT_EXCEPTION:
+            reason = 'exception'
+        elif reason == pydevd_comm.CMD_SET_BREAK:
+            reason = 'breakpoint'
+        else:
+            reason = 'pause'
+        with self.stack_traces_lock:            
+            self.stack_traces[tid] = xml.thread.frame
+        tid = self.thread_map.to_vscode(tid)
+        self.send_event('stopped', reason=reason, threadId=tid)
+
+    @pydevd_events.handler(pydevd_comm.CMD_THREAD_RUN)
+    def on_pydevd_thread_run(self, seq, args):
+        pyd_tid, reason = args.split('\t')
+        vsc_tid = self.thread_map.to_vscode(pyd_tid)
+
+        # Stack trace, and all frames and variables for this thread are now invalid; clear their IDs.
+        with self.stack_traces_lock:
+            del self.stack_traces[pyd_tid]
+
+        for pyd_fid, vsc_fid in self.frame_map.pairs():
+            if pyd_fid[0] == pyd_tid:
+                self.frame_map.remove(pyd_fid, vsc_fid)
+
+        for pyd_var, vsc_var in self.var_map.pairs():
+            if pyd_var[0] == pyd_tid:
+                self.var_map.remove(pyd_var, vsc_var)
+
+        self.send_event('continued', threadId=vsc_tid)
+
+    @pydevd_events.handler(pydevd_comm.CMD_SEND_CURR_EXCEPTION_TRACE)
+    def on_pydevd_send_curr_exception_trace(self, seq, args):
+        _, name, description, xml = args.split('\t')
+        xml = untangle.parse(xml).xml
+        pyd_tid = xml.thread['id']
+        with self.active_exceptions_lock:
+            self.active_exceptions[pyd_tid] = ExceptionInfo(name, description)
+
+    @pydevd_events.handler(pydevd_comm.CMD_SEND_CURR_EXCEPTION_TRACE_PROCEEDED)
+    def on_pydevd_send_curr_exception_trace_proceeded(self, seq, args):
+        pass
+
+
+def start_server(port):
+    server = socket.socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_TCP)
+    server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    server.bind(('127.0.0.1', port))
+    server.listen(1)
+    client, addr = server.accept()
+
+    pydevd = PydevdSocket(lambda *args: proc.on_pydevd_event(*args))
+    proc = VSCodeMessageProcessor(client, pydevd)
+
+    server_thread = threading.Thread(target = proc.process_messages, name = 'ptvsd.Server')
+    server_thread.start()
+
+    return pydevd
+
+def start_client(host, port):
+    client = socket.socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_TCP)
+    client.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    client.connect((host, port))
+
+    pydevd = PydevdSocket(lambda *args: proc.on_pydevd_event(*args))
+    proc = VSCodeMessageProcessor(client, pydevd)
+
+    server_thread = threading.Thread(target = proc.process_messages, name = 'ptvsd.Client')
+    server_thread.start()
+
+    return pydevd
+  
+# These are the functions pydevd invokes to get a socket to the client.
+pydevd_comm.start_server = start_server
+pydevd_comm.start_client = start_client
diff --git a/setup.cfg b/setup.cfg
new file mode 100644
index 00000000..5e409001
--- /dev/null
+++ b/setup.cfg
@@ -0,0 +1,2 @@
+[wheel]
+universal = 1
diff --git a/setup.py b/setup.py
new file mode 100644
index 00000000..f086441e
--- /dev/null
+++ b/setup.py
@@ -0,0 +1,24 @@
+#!/usr/bin/env python
+
+# Copyright (c) Microsoft Corporation. All rights reserved.
+# Licensed under the MIT License. See LICENSE in the project root for license information.
+
+import sys
+from setuptools import setup
+
+setup(name='ptvsd',
+      version='4.0.0a1',
+      description='Visual Studio remote debugging server for Python',
+      license='MIT',
+      author='Microsoft Corporation',
+      author_email='ptvshelp@microsoft.com',
+      url='https://aka.ms/ptvs',
+      classifiers=[
+        'Development Status :: 3 - Alpha',
+        'Programming Language :: Python',
+        'Programming Language :: Python :: 2',
+        'Programming Language :: Python :: 3',
+        'License :: OSI Approved :: MIT License'],
+      packages=['ptvsd'],
+      install_requires=['untangle', 'pydevd>=1.1.1']
+     )