Scalable Chat App

Normal Chat App

graph BT;
A[User 1]
B[User 2]
C[Server<br>socket.io]
A-->C
B-->C

• No problem till now because both the users are connected with same server so here socket connect is successful
• Now some a day load on server is increased so i though waht can we do
  • We can do vetical scalling increased the system property whre the system is hosted
  • Now if after some day we reached the limit of increament and users are increasing day by day
  • so we will introduce one more server
  • so here we are goint to do Horizontally scalling

graph BT;
A[User 1]
B[User 2]
D[User 3]
C[Server 1<br>socket.io]
A-->C
B-->C
e[Server 2<br>socket.io]
D-->e

• so here socket connection is not possible between User 1 and User 3

graph BT;
A[User 1]
B[User 2]
D[User 3]
C[Server 1<br>socket.io]
A-->C
B-->C
e[Server 2<br>socket.io]
D-->e
E[Redis]
C-->E
e-->E

• Now our problem is resolved all the users are connected with each other
• Now we will save datas to our database

graph BT;
A[User 1]
B[User 2]
D[User 3]
C[Server 1<br>socket.io]
A-->C
B-->C
e[Server 2<br>socket.io]
D-->e
E[Redis]
C-->E
e-->E
E-->F(PSQL)

• Now here one problem arises like now read and write to database is increased so our database can be down after some times
• so now what we will do

graph BT;
A[User 1]
B[User 2]
D[User 3]
C[Server 1<br>socket.io]
A-->C
B-->C
e[Server 2<br>socket.io]
D-->e
E[Redis]
C-->E
e-->E
E-->G
G(Kafka)
F(PSQL)
G-->F