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Design of IM login server and message server

2022-06-25 05:23:00 【I want to be a fool, too】

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2 IM Login server and message server design

1. Communication protocol design

2. reactor Model

3. login_server analysis

4. Database design

5. Login business analysis

6. msg_server analysis

0 Source code distribution

0voice_im\server\src
base Basic components
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1. 1 Communication protocol design - Format

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1. 2 Communication protocol design -protobuf

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1.3 Communication protocol design - Structure

typedef struct {
	uint32_t length; // the whole pdu length  Represents this package 
	uint16_t version; // pdu version number
	uint16_t flag; // not used
	uint16_t service_id; //
	uint16_t command_id; //
	uint16_t seq_num; //  Package number 
	uint16_t reversed; //  Retain 
} PduHeader_t;

Header + body

1.4 Communication protocol design - Package integrity judgment 1

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1. Socket TCP（ reliability ）
2. Boundary treatment of protocol design header + body, adopt header Of
length Field （ 4 byte ） solve
3. Service ID and Command ID Distinguish between different commands
4. TCP The problem of sticking packets is solved by caching data

1.4 Communication protocol design - Package integrity judgment 2

CImPdu::ReadPdu
CImConn::OnRead
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2 login_server analysis

login_server

This service is used for load balancing
Yes

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3.1 reactor Model -CBaseSocket

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socket Custom state ：
SOCKET_STATE_IDLE ：CBaseSocket()
SOCKET_STATE_LISTENING：Listen()  As server When 
SOCKET_STATE_CONNECTING :Connect()  As client When 
SOCKET_STATE_CONNECTED: OnWrite()  As client When 
SOCKET_STATE_CLOSING: OnClose()

CBaseSocket： management socket io, As client perhaps server You need to instantiate one CBaseSocket

hash_map<net_handle_t, CBaseSocket*> SocketMap;  All connection management , With fd by key,
CBaseSocket The object is value, Deal with ：

void AddBaseSocket(CBaseSocket* pSocket) increase
void RemoveBaseSocket(CBaseSocket* pSocket) Delete
CBaseSocket* FindBaseSocket(net_handle_tfd) check

3.2 reactor Model -CEventDispatch

CEventDispatch yes reactor The trigger of ,epoll Relevant functions are called here .

Timer relevant 
AddTimer： Add scheduled events 
RemoveTimer： Delete scheduled events 
_CheckTimer： Detect scheduled events

Loop relevant 
AddLoop： Add loop Events 
_CheckLoop： Detect loop events

epoll relevant 
AddEvent：  add to fd event 
RemoveEvent： Delete fd event 
StartDispatch： Get into reactor Main circulation 
StopDispatch： stop it reactor Main circulation

3.3 reactor Model -api netlib

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CEventDispatch yes reactor The trigger of , But not externally api,netlib It's external api.

fd relevant 
 netlib_listen： monitor 
 netlib_connect： Connect 
 netlib_send： send out 
 netlib_recv： receive 
 netlib_close： close 
 netlib_option： Parameter setting 
 NETLIB_OPT_SET_CALLBACK Set the callback function

Timer related

 netlib_register_timer： Register timer 
 netlib_delete_timer： Delete timer

 Cyclic correlation 
 netlib_add_loop： You can add transactions that need to be processed circularly to reactor
 netlib_eventloop： Get into reactor Main circulation

3.4 reactor Model -http Service and IM The difference between agreements

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Listen  Set callback 
netlib_option：NETLIB_OPT_SET_CALLBACK  Set the callback function

login_server.cpp

4 Database design

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5.1 Log in to business

Login account verification and status synchronization

User name and password verification

Online status settings + Route status update

The old client account goes offline

Notify friends , Mobile era , 24 Hours at school

Login data preparation

Group information

The friends list

Group list

Friend information

Unread message

other …

5.1 Log in to business - To continue 1

Login account verification and status synchronization

User name and password verification

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Online status settings + Route status update

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 Client status

 Server status

 Route status update

Plaintext passwords cannot be used

 client  md5(password)

5.1 Log in to business - To continue 2 The old client account goes offline

Login account verification and status synchronization

If the account is already logged in , Then force it offline

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The office pc Sign in
（ 1 ） There is no problem logging in from the mobile phone
（ 2 ） If at home pc Sign in , Office offline

2 Mobile phone login
（ 1 ） Change your mobile phone and log in , Previous mobile phones were offline
(2 ) If you use pc Sign in , No problem , Tips pc Login