What is the difference between Web sockets per instance and IP connections?
Reference: https://learn.microsoft.com/en-us/azure/azure-resource-manager/management/azure-subscription-service-limits#managing-limits
WebSocket protocol enables a full duplex communication between a server and a client over a long running TCP connection. In a simple word, WebSocket uses TCP/IP to communicate.
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Hello, 👋
I was wondering how services (like mysql, apache, mongoDB) are bind against a port in the server/local machine. How does this work?
I'm guessing that when the service starts, it tries to connect to the port and if possible, the service is "paused" until the OS receives a request against the selected port. Is there any documentation out explaining how this works?
Thank you!
May I help you?
This is a list of TCP and UDP port numbers used by protocols for operation of network applications.
The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) only need one port for duplex, bidirectional traffic. They usually use port numbers that match the services of the corresponding TCP or UDP implementation, if they exist.
I am trying to create a simplistic TCP client and server. Conceptually, I know that a TCP socket is the same on both the client and server side (at least, this is how it is in python). However, the steps after creating a socket are different. Ie, for clients, the socket establishes a TCP connection to the server. On the server side, the socket is bound to a specific port, and waits for connections, and when it gets a req, it creates a new connected socket. (correct me if I got anything wrong, I'm new to networking).
My question is if there's any difference between the net.Socket and net.Server classes. Did node.js separate the two, and net.Server is explicitly meant for servers? Is it still possible to use net.Socket to make the TCP server socket?
What is the difference between net.createServer() and net.createConnection()?
net.createConnection() initiates an outbound TCP connection to some other host or server.
net.createServer() sets up a server that will accept incoming TCP connections from other hosts or processes.
These are opposite ends of enabling a connection.
My question is if there's any difference between the net.Socket and net.Server classes.
Yes, there's a huge difference between them as neither is a substitute for the other. A server listens for inbound connections.
A client then creates a TCP socket and attempts to connect to a server that is listening for inbound connections on the port and IP address that the server is listening on. During the connection process, the server follows the TCP handshake process to enable the creation of a TCP socket that connects the client and server. That TCP socket is then bidirectional so either end can then send data to the other.
Nodejs uses the net.Socket class as the nodejs object to represent a TCP socket so when you initiate a connection from a client, you get a net.Socket object that represents your TCP connection to some other server. When you are a server and someone connects to you, you get a net.Socket object that represents your TCP connection to the client that connected to you. Those two objects are different ends of a TCP connection and both ends do not have to be nodejs endpoints - they can be any language or tool that can make a standard TCP connection.
Did node.js separate the two, and net.Server is explicitly meant for servers? Is it still possible to use net.Socket to make the TCP server socket?
Yes, net.Server is exclusively for servers to set up a listener for inbound connections on a specific port on your host.
net.socket by itself cannot listen to incoming connections (you use an instance on net.Server for that. It is either used to initiate a TCP connection to some server or it is created as part of of some client connecting to your server.
I am trying to create a multi room chat application in node.js using socket.io and express. I am confused between use of server port and websocket port. I understand server port is used by the client to connect to server. But not sure about use of websocket port.
Thanks & Regards..
webSockets can share the same port as your web server and this is a common configuration. The reason this works is because of how a webSocket establishes a connection (all webSocket connections are initiated with an HTTP request). It works like this:
Client makes an HTTP request to a web server with a header specifying that they want to "upgrade" to the webSocket protocol and sends a security-related header.
Web server sees the upgrade request and, if it has support enabled for webSocket connections, it will respond with a 101 request (switching protocols) and another security related header.
Client gets the accepted upgrade and both ends switch to the webSocket protocol and the original TCP socket that started out using the HTTP protocol is now using the webSocket protocol.
In this manner, the same port and webServer can be used for regular HTTP requests or webSocket connection requests.
For a chat application it is common to use a webSocket connection because it is a continuous connection that more easily allows the server to send information directly to the client which is often needed in a chat application.
To understand more about how a webSocket connection and server work, see this reference on MDN: Writing WebSocket servers which shows the step by step process for initiating a webSocket connection.
Server socket is used by server... that keeps listening to coming sockets request in a loop... and websocket sends a request to server socket and bound a connection between two devices...
If you have / want to have web clients, WebSocket is going to be required, because there is no access to 'regular' TCP (or UDP) sockets from browser-based JavaScript (and I assume you do not want Flash, SilverLight or Java Applets, in 2017). WebSocket is not special because of the port number, but it is special because of the protocol: a WebSocket connection starts as a regular HTTP connection, and protocol upgrade reconfigures it afterwards, it is designed for the browser-world, and even capable of traversing HTTP proxies. After establishing the connection, it provides a full-duplex, bi-directional message stream, very usable for chat applications.
And because of being a Web-thing, you could simply use port 80, if you are allowed to.
I have to implement a server to server communication protocol using a SINGLE PERSISTENT TCP connection. The server at both the ends of this connection are implemented using "multi-threaded and asynchronous event-driven model". Both these servers are implemented in C++ and Pthreads on Linux. Server A always sends requests to Server B and Server B responds with a response. Server B doesn't send any requests to Server A, it just responds to the requests it receives. Could some one post me a sample code for this communication? Could you help me with the code for both Server A and Server B? Or please point me to any old answers or any websites where i can find a prototype code. Thanks in advance.
TCP servers cannot open connections to TCP servers. There is no IP protocol for that. One of the two servers must run a TCP client as a subsystem. The exact mechanics of how you do that depend on your client<>server protocol - the 'server-client' could log in to the 'client-server' with a unique username/password, or could use a different server listening port.
It's up to you:)
I have many linux servers (cluster) to run my application.The application use C/S structure,client connect to server using TCP long connection(server is basing apache mina socket framework).
my question is : When one server shutdown, how other servers can keep the socket connection established between the failure server and the clients?
so the server-down failure can be transparent to clients and clients need not reconnect to server.
Thanks
L.J.W
You cannot simply migrate a TCP connection unless there is some kind of never-failing proxy in between like a layer-4-switch.