Rename and relocate CDC Python examples

Moved the CDC example scripts into the protocol directory and added the .py
suffix. Fixed all references to these scripts.

server/modules/protocol/examples/cdc.py

@@ -0,0 +1,97 @@
+#!/usr/bin/env python3
+
+# Copyright (c) 2016 MariaDB Corporation Ab
+#
+# Use of this software is governed by the Business Source License included
+# in the LICENSE.TXT file and at www.mariadb.com/bsl.
+#
+# Change Date: 2019-01-01
+#
+# On the date above, in accordance with the Business Source License, use
+# of this software will be governed by version 2 or later of the General
+# Public License.
+
+import time
+import json
+import re
+import sys
+import socket
+import hashlib
+import argparse
+import subprocess
+import selectors
+import binascii
+import os
+
+# Read data as JSON
+def read_json():
+    decoder = json.JSONDecoder()
+    rbuf = bytes()
+    ep = selectors.EpollSelector()
+    ep.register(sock, selectors.EVENT_READ)
+
+    while True:
+        pollrc = ep.select(timeout=int(opts.read_timeout) if int(opts.read_timeout) > 0 else None)
+        try:
+            buf = sock.recv(4096, socket.MSG_DONTWAIT)
+            rbuf += buf
+            while True:
+                rbuf = rbuf.lstrip()
+                data = decoder.raw_decode(rbuf.decode('ascii'))
+                rbuf = rbuf[data[1]:]
+                print(json.dumps(data[0]))
+        except ValueError as err:
+            sys.stdout.flush()
+            pass
+        except Exception:
+            break
+
+# Read data as Avro
+def read_avro():
+    ep = selectors.EpollSelector()
+    ep.register(sock, selectors.EVENT_READ)
+
+    while True:
+        pollrc = ep.select(timeout=int(opts.read_timeout) if int(opts.read_timeout) > 0 else None)
+        try:
+            buf = sock.recv(4096, socket.MSG_DONTWAIT)
+            os.write(sys.stdout.fileno(), buf)
+            sys.stdout.flush()
+        except Exception:
+            break
+
+parser = argparse.ArgumentParser(description = "CDC Binary consumer", conflict_handler="resolve")
+parser.add_argument("-h", "--host", dest="host", help="Network address where the connection is made", default="localhost")
+parser.add_argument("-P", "--port", dest="port", help="Port where the connection is made", default="4001")
+parser.add_argument("-u", "--user", dest="user", help="Username used when connecting", default="")
+parser.add_argument("-p", "--password", dest="password", help="Password used when connecting", default="")
+parser.add_argument("-f", "--format", dest="format", help="Data transmission format", default="JSON", choices=["AVRO", "JSON"])
+parser.add_argument("-t", "--timeout", dest="read_timeout", help="Read timeout", default=0)
+parser.add_argument("FILE", help="Requested table name in the following format: DATABASE.TABLE[.VERSION]")
+parser.add_argument("GTID", help="Requested GTID position", default=None, nargs='?')
+
+opts = parser.parse_args(sys.argv[1:])
+
+sock = socket.create_connection([opts.host, opts.port])
+
+# Authentication
+auth_string = binascii.b2a_hex((opts.user + ":").encode())
+auth_string += bytes(hashlib.sha1(opts.password.encode("utf_8")).hexdigest().encode())
+sock.send(auth_string)
+
+# Discard the response
+response = str(sock.recv(1024)).encode('utf_8')
+
+# Register as a client as request Avro format data
+sock.send(bytes(("REGISTER UUID=XXX-YYY_YYY, TYPE=" + opts.format).encode()))
+
+# Discard the response again
+response = str(sock.recv(1024)).encode('utf_8')
+
+# Request a data stream
+sock.send(bytes(("REQUEST-DATA " + opts.FILE + (" " + opts.GTID if opts.GTID else "")).encode()))
+
+if opts.format == "JSON":
+    read_json()
+elif opts.format == "AVRO":
+    read_avro()