diff --git a/asynci/core/rpc.py b/asynci/core/rpc.py
new file mode 100644
index 0000000..3f96336
--- /dev/null
+++ b/asynci/core/rpc.py
@@ -0,0 +1,74 @@
+import abc
+import asyncio
+import struct
+
+
+class __InternalProtocol(asyncio.Protocol):
+    __reader:asyncio.StreamReader
+
+    def __init__(self, reader:asyncio.StreamReader):
+        assert isinstance(reader, asyncio.StreamReader)
+        self.__reader = reader
+
+    async def _drain_helper(self):
+        pass
+
+
+class __InternalTransport(asyncio.WriteTransport):
+    __close: bool
+    __reader: asyncio.StreamReader
+
+    def __init__(self, reader: asyncio.StreamReader):
+        self.__close = True
+        assert isinstance(reader, asyncio.StreamReader)
+        self.__reader = reader
+
+    def close(self):
+        self.__close = False
+        self.__reader.feed_eof()
+
+    def is_closing(self):
+        return not self.__close
+
+    def write(self, data: bytes):
+        self.__reader.feed_data(data)
+
+
+def create_internal_stream(loop=None):
+    if loop is None:
+        loop = asyncio.get_event_loop()
+    reader = asyncio.StreamReader(loop=None)
+    internal_protocol = __InternalProtocol(reader)
+    internal_transport = __InternalTransport(reader)
+    writer = asyncio.StreamWriter(internal_transport, internal_protocol, reader=reader, loop=loop)
+    return reader, writer
+
+
+class BaseConnectionServer(abc.ABC):
+    __in:asyncio.StreamReader
+    __out:asyncio.StreamWriter
+    __size_format = struct.Struct("!I")
+
+    def __init__(self, in_io:asyncio.StreamReader, out_io:asyncio.StreamWriter):
+        if not isinstance(in_io, asyncio.StreamReader):
+            raise TypeError("in_io have to be a stream reader.")
+        if not isinstance(out_io, asyncio.StreamWriter):
+            raise TypeError("out_io have to be a stream writer.")
+        self.__in, self.__out = in_io, out_io
+
+    async def init(self):
+        # Send own config
+        self.__out.write(self.__size_format.pack(0))
+        await self.__out.drain()
+
+        # Read other config
+        size = self.__size_format.unpack(await self.__in.readexactly(self.__size_format.size))[0]
+        await self.__in.readexactly(size)
+
+        # Send applied config
+        self.__out.write(self.__size_format.pack(0))
+        await self.__out.drain()
+
+        # Read other applied config
+        size = self.__size_format.unpack(await self.__in.readexactly(self.__size_format.size))[0]
+        await self.__in.readexactly(size)
diff --git a/tests/asynci_core_rpc.py b/tests/asynci_core_rpc.py
new file mode 100644
index 0000000..88b871f
--- /dev/null
+++ b/tests/asynci_core_rpc.py
@@ -0,0 +1,43 @@
+from asynci.core import rpc
+import asyncio
+import unittest
+
+
+class TestInternal(unittest.IsolatedAsyncioTestCase):
+    async def test_create(self):
+        reader, writer = rpc.create_internal_stream()
+
+    async def test_close_read(self):
+        reader, writer = rpc.create_internal_stream()
+        writer.close()
+        await writer.drain()
+        self.assertEqual(await reader.read(10), b"")
+
+    async def test_write(self):
+        reader, writer = rpc.create_internal_stream()
+        writer.write(b"abc")
+        writer.close()
+        await writer.drain()
+        self.assertEqual(await reader.read(), b"abc")
+
+    async def test_writelines(self):
+        reader, writer = rpc.create_internal_stream()
+        writer.writelines([b"a", b"b"])
+        writer.close()
+        await writer.drain()
+        self.assertEqual(await reader.read(), b"ab")
+
+
+class _BCS(rpc.BaseConnectionServer):
+    pass
+
+
+class TestBaseConnectionServer(unittest.IsolatedAsyncioTestCase):
+    async def test_create(self):
+        reader, writer = rpc.create_internal_stream()
+        _BCS(reader, writer)
+
+    async def test_init(self):
+        reader, writer = rpc.create_internal_stream()
+        bcs = _BCS(reader, writer)
+        await bcs.init()