diff --git a/daiquiri/server/server_agent.py b/daiquiri/server/server_agent.py
new file mode 100644
index 0000000..ff8f95f
--- /dev/null
+++ b/daiquiri/server/server_agent.py
@@ -0,0 +1,103 @@
+# =============================================================================
+# IMPORTS
+# =============================================================================
+import abc
+import os
+
+# =============================================================================
+# MODULE CLASSES
+# =============================================================================
+
+class ServerAgentBase(abc.ABC):
+    """ Base class for server agent.
+
+    Methods
+    -------
+    upload
+    download
+    """
+    def __init__(self, *args, **kwargs):
+        super(UserAgentBase, self).__init__()
+
+    @abc.abstractmethod
+    def receive(self, *args, **kwargs):
+        raise NotImplementedError
+
+    @abc.abstractmethod
+    def send(self, *args, **kwargs):
+        raise NotImplementedError
+
+class SocketServerAgent(ServerAgentBase):
+    """ User agent with `socket` package.
+
+    """
+    def __init__(self, sock):
+        super(SocketServerAgent, self).__init__()
+
+        # local imports
+        import socket
+        self.sock = sock
+
+    def send(self, path, buffer_size=1024):
+        """ Upload file using socket.
+
+        """
+
+        # send size
+        sock.send('size' + str(
+            os.path.getsize(path)))
+
+        # send name
+        sock.send(
+            os.path.basename(path))
+
+        with open(path, 'rb') as f_handle:
+            # get data
+            data = f.read(buffer_size)
+            
+            # send data
+            self.sock.send(data)
+
+            # TODO:
+            # shall we use len() == 0 or equivalent
+            # since there could be various encodings?
+            # not sure
+            while data != '':
+                data = f_handle.read(buffer_size)
+                self.send(data)
+
+        self.sock.close()
+
+    def receive(self, path, buffer_size=1024):
+        """ Download file using socket.
+
+        """
+        # get size
+        # TODO: is this hard-coded `4` right?
+        size = int(self.sock.recv(buffer_size)[4:])
+
+        # TODO:
+        # this is not consistent with your original implemtation,
+        # the file name argument should be speicifed, right?
+        with open(path, 'wb') as f_handle:
+            # initial receive
+            data = sock.recv(buffer_size)
+
+            # get total receive
+            total_recv = len(data)
+
+            # write to file
+            f_handle.write(data)
+
+            while total_recv < size:
+                data = sock.recv(buffer_size)
+                total_recv += len(data)
+                f_handle.write(data)
+
+
+
+
+
+
+
+
diff --git a/daiquiri/submitter/user_agent.py b/daiquiri/submitter/user_agent.py
new file mode 100644
index 0000000..38e7dc9
--- /dev/null
+++ b/daiquiri/submitter/user_agent.py
@@ -0,0 +1,92 @@
+# =============================================================================
+# IMPORTS
+# =============================================================================
+import abc
+import os
+
+# =============================================================================
+# MODULE CLASSES
+# =============================================================================
+
+class SubmitterAgentBase(abc.ABC):
+    """ Base class for submitter agent.
+
+    Methods
+    -------
+    upload
+    download
+    """
+    def __init__(self, *args, **kwargs):
+        super(UserAgentBase, self).__init__()
+
+    @abc.abstractmethod
+    def upload(self, *args, **kwargs):
+        raise NotImplementedError
+
+    @abc.abstractmethod
+    def download(self, *args, **kwargs):
+        raise NotImplementedError
+
+class SocketSubmitterAgent(SubmitterAgentBase):
+    """ User agent with `socket` package.
+
+    """
+    def __init__(self, sock):
+        super(SocketSubmitterAgent, self).__init__()
+
+        # local imports
+        import socket
+        self.sock = sock
+
+    def upload(self, path, buffer_size=1024):
+        """ Upload file using socket.
+
+        """
+        assert os.path.isfile(path), 'Path does not exist.'
+
+        # send size
+        sock.send('size' + str(
+            os.path.getsize(path)))
+
+        with open(path, 'rb') as f_handle:
+            # get data
+            data = f.read(buffer_size)
+            
+            # send data
+            self.sock.send(data)
+
+        self.sock.close()
+
+    def download(self, path, buffer_size=1024):
+        """ Download file using socket.
+
+        """
+        # get size
+        # TODO: is this hard-coded `4` right?
+        size = int(self.sock.recv(buffer_size)[4:])
+
+        # TODO:
+        # this is not consistent with your original implemtation,
+        # the file name argument should be speicifed, right?
+        with open(path, 'wb') as f_handle:
+            # initial receive
+            data = sock.recv(buffer_size)
+
+            # get total receive
+            total_recv = len(data)
+
+            # write to file
+            f_handle.write(data)
+
+            while total_recv < size:
+                data = sock.recv(buffer_size)
+                total_recv += len(data)
+                f_handle.write(data)
+
+
+
+
+
+
+
+