I’m tring to write an application with protocol buffers to send data on socket connecet.I encountered some problems , this is my summary:
###Pre preparation
#####1.download Google protocol buffers.
look at this https://developers.google.com/protocol-buffers/
#####2.Buliding Google protocol buffers(Python).
if you see ‘…no module name google.protobuf..’ do this in Terminal:
(sudo)pip install protobuf
#####3.To understanding struct
###Main body
####Client
import edu_pb2
.
.
.
line = edu_pb2.Eline()
line.id = 1000
line.width = 1
line.color = -16777216
protobuf_data = line.SerializeToString()#Serialize
type = 1001
packed_len = struct.pack('LL',type,len(protobuf_data))
call(["ls","-l"])
# str2 = struct.unpack('LL', packed_len)
# print str2 #(1000,-16777216)
sock.sendall(packed_len+protobuf_data)struct.pack('LL',type,len(protobuf_data))
‘LL’ means two long types,more types looks here
###Server
first in server i def a funcation name socket_read_n
def socket_read_n(sock, n):
""" Read exactly n bytes from the socket.
Raise RuntimeError if the connection closed before
n bytes were read.
"""
buf = ''
while n > 0:
data = sock.recv(n)
if data == '':
raise RuntimeError('unexpected connection close')
buf += data
n -= len(data)
return bufthen .
len_buf = socket_read_n(sock, 8)
type = struct.unpack('>LL', len_buf)[0]
msg_len = struct.unpack('>LL', len_buf)[1]
print(type)#1001
msg_buf = socket_read_n(sock, msg_len)
msg = edu_pb2.ELine()
msg.ParseFromString(msg_buf)
print(msg)enjoy it!
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