reading-notes

---

Project maintained by Razan-am Hosted on GitHub Pages — Theme by mattgraham

Message Queues

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

• 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. Yes it’s useful.

Does socket.io use HTTP? Why?

• Yes it’s use it but it doesn’t need an HTTP server to regular websockets,but it is used to allow HTTP and websocket servers to co-exist on the same TCP port.

What happens when a client emits an event?

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

What happens when a server emits an event?

• It will send an event called message to the client, after the client connects. The send function on socket object associates the ‘message’ event.

What happens if a client “misses” an event?

• The events will be ignored

How can we mitigate this?

• You could avoid missing messages by always having the handlers and then deciding in the handlers whether to do anything with the message or not.

Sockets work based on events. There are some reserved events, which can be accessed using the socket object on the server side.These are :

1. Connect
2. Message
3. Disconnect
4. Reconnect
5. Ping
6. Join and
7. Leave.

The client-side socket object also provides us with some reserved events, which are :

1. Connect
2. Connect_error
3. Connect_timeout
4. Reconnect, etc.

---

Terms

• Socket: it was created to use open connections to facilitate realtime communication, still a relatively new phenomenon at the time.

• Web Socket: it is an advanced technology that makes it possible to open a two-way interactive communication session between the user’s browser and a server.

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

• Client: a computer hardware device or software that accesses a service made available by a server.

• Server: is a physical computer dedicated to run services to serve the needs of other computers. Depending on the service that is running, it could be a file server, database server, home media server, print server, or web server.

• OSI Model: The Open Systems Interconnection (OSI) model describes seven layers that computer systems use to communicate over a network.

• TCP Model: TCP model defines how devices should transmit data between them and enables communication over networks and large distances. The model represents how data is exchanged and organized over networks.

• TCP: TCP stands for Transmission Control Protocol a communications standard that enables application programs and computing devices to exchange messages over a network.

• UDP: User Datagram Protocol, or UDP, is a communication protocol used across the Internet for especially time-sensitive transmissions such as video playback or DNS lookups.

• Packets: it is a small segment of a larger message.

---

References:

@By Socket.IO/Socket.IO

@By Glyn Lewington/Everything You Need To Know About Socket.IO

@By stackoverflow/SOCKET