Message Queues

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• What does it mean that web sockets are bidirectional? Why is this useful?

web sockets are bidirectional means it handles both client-side and server-side. Whereas HTTP relies on a client request to receive a response from the server for every exchange, WebSockets allow for full-duplex bidirectional communication. This enables the server to send real-time updates asynchronously, without requiring the client to submit a request each time.

• Does socket.io use HTTP? Why?

no, Socket.IO is always dependent on a http server

• What happens when a client emits an event?

the event gets passed to the server through websockets. Its a tcp connection from the browser to the server. The connection is full duplex meaning the server can send real time data to the client and vise versa.

• What happens when a server emits an event?

when the server listen to the connection event. When that event is invoked, socket.io pass a socket object to our function. We then listen to all of our sockets for a chat. As defined on the client side, take the data emited from the chat and emit it back to all of our sockets.

• What happens if a client “misses” an event?

it stored in queue until the client get opportunity to listen the event.

• How can we mitigate this? we will push a missed event to the Buffers until it is consumed(used).

Terms

• Socket

a socket is an endpoint of a communication between two programs running on a network. Sockets are used to create a connection between a client program and a server program

• Web Socket

The WebSocket object provides the API for creating and managing a WebSocket connection to a server, as well as for sending and receiving data on the connection.

• Socket.io Socket.IO is a library that enables real-time, bidirectional and event-based communication between the browser and the server.

• Client

The Clients interface provides access to Client objects.

• Server

framework can be used to develop web servers using the ‘http’ module.

• OSI Model

The OSI model is an architectural model that represents networking communications.

• TCP Model

TCP (Transmission Control Protocol) is a protocol for sending information between computers.

• TCP

TCP (Transmission Control Protocol) is a protocol for sending information between computers.

• UDP

UDP (User Datagram Protocol) is a long standing protocol used together with IP for sending data when transmission speed and efficiency matter more than security and reliability.

• Packets

a packet is a small segment of a larger message. Data sent over computer networks*, such as the Internet, is divided into - packets.

Socket.io Chat example

Sockets have traditionally been the solution around which most real-time chat systems are architected, providing a bi-directional communication channel between a client and a server The server can push messages to clients

Whenever you write a chat message, the idea is that the server will get it and push it to all other connected clients Setup steps here

• Rooms and Namespaces

Room is an arbitrary channel that sockets can join and leave, it can be used to broadcast events to a subset of clients Rooms are a server-only concept (client does not have access to the list of rooms it has joined) Can join to subscribe the socket to a given channel socket.join()

Each socket in Socket.io is identified by a random unique identifier (Socket#id), each socket automatically joins a room identified by its own id

Upon disconnection, sockets leave all the channels they were part of automatically.

references

chat example on socket.io

rooms

nameSpaces

cheatSheet