Lets say I have a tablet PC running a GUI application, and a remote PC (with static IP) running the backend core stuff.
The application running on the PC should request information from the Server.
Now I was thinking of socket programming, where the server will be running a server socket application and the tablet PC a client socket application.
But is there a simpler thing? I know ftp protocol is used to transfer files, is there a high level protocol like ftp that can be used to transfer small binary data, 16 bits per request? so I don't have to do any socket programming?
If the answer is only using socket programming, how to do that?
If I understand correctly, what you really want is an Application Server. If you choose to use sockets, you will have to deal with a lot of low-level details, such as marshalling / unmarshalling. You can opt for a higher-level solution:
CORBA;
PHP-based web server, perhaps using REST for transferring requests / replies;
add your favourite RPC / RMI framework here.
Socket programming is indeed what you want here. Check out Beej's Guide to Network Programming to get yourself started.
Related
What are the advantages and disadvantages of using only socket based communication vs a hybrid of REST and socket (using socket only when bidirectional communication is necessary, like receiving messages in a chat).
When I say only socket, I mean that instead of sending a GET request asking for /entities, I'd send update_needed and the server would send a push via socket.
My question is not really about performance, it's more about the concept, like delegate vs block/lambda (using socket would be like the delegate concept and REST is more like block).
It all boils down to what type of application and level of scalability you have in mind.
WebSocket/REST: Client connections?
How to handle CQRS from a client-side perspective
Hard downsides of long polling?
The main reason why I wouldn't use WebSockets in any major project is simply that still many users don't use a modern browser that support them. Namely IE 8 and 9 don't support them and both together still have a market share of over 20 % (Oct 15).
I am busy creating a system where various PCs communicate with each other over the internet. How it works at the moment, is each PC is a client and logs onto the server. Currently, there is a normal java program running on my own server with listening sockets that handles incoming requests and then relays the information between the connected PCs. My question is, is this a proper way of doing it? Should I rather change the app to a service or should I use something like a webservice? Also, is it fine using TCP sockets for the communication?
If I don't want to run the program on my own server, what type of company can offer me such a service where I can run my own apps?
I want to expand the current setup to a larger scale, so I want to make sure I am using good practices and keep hackers out.
Thanks
I'm building web app that needs to communicate with another application using socket connections. This is new territory for me, so want to be sure that sockets are different than websockets. It seems like they're only conceptually similar.
Asking because initially I'd planned on using Django as the foundation for my project, but in the SO post I linked to above it's made very clear that websockets aren't possible (or at least not reliable, even with something like django-websockets) using the preferred Django setup (Apache with mod_wsgi). Yet I've found other posts that casually import Python's socket module for something as simple as grabbing the server's hostname.
So:
Are they really different?
Is there any reason not to use Django for a project that relies on establishing socket connections with an outside server?
To answer your questions.
Even though they achieve (in general) similar things, yes, they are really different. WebSockets typically run from browsers connecting to Application Server over a protocol similar to HTTP that runs over TCP/IP. So they are primarily for Web Applications that require a permanent connection to its server. On the other hand, plain sockets are more powerful and generic. They run over TCP/IP but they are not restricted to browsers or HTTP protocol. They could be used to implement any kind of communication.
No. There is no reason.
Websockets use sockets in their implementation. Websockets are based on a standard protocol (now in final call, but not yet final) that defines a connection "handshake" and message "frame." The two sides go through the handshake procedure to mutually accept a connection and then use the standard message format ("frame") to pass messages back and forth.
I'm developing a framework that will allow you to communicate directly machine to machine with installed software. It might suit your purpose. You can follow my blog if you wish: http://highlevellogic.blogspot.com/2011/09/websocket-server-demonstration_26.html
WebSocket is just another application level protocol over TCP protocol, just like HTTP.
Some snippets < Spring in Action 4> quoted below, hope it can help you understand WebSocket better.
In its simplest form, a WebSocket is just a communication channel
between two applications (not necessarily a browser is
involved)...WebSocket communication can be used between any kinds of
applications, but the most common use of WebSocket is to facilitate
communication between a server application and a browser-based application.
You'd have to use WebSockets (or some similar protocol module e.g. as supported by the Flash plugin) because a normal browser application simply can't open a pure TCP socket.
The Socket.IO module available for node.js can help a lot, but note that it is not a pure WebSocket module in its own right.
It's actually a more generic communications module that can run on top of various other network protocols, including WebSockets, and Flash sockets.
Hence if you want to use Socket.IO on the server end you must also use their client code and objects. You can't easily make raw WebSocket connections to a socket.io server as you'd have to emulate their message protocol.
WebSocket is a computer communications transport protocol (like TCP, HTTP 1.0, HTTP 1.1, HTTP 2.0, QUIC, WebRTC, etc.)
Socket is an endpoint for sending and receiving data across the network (like Port number)
Example of Socket:
(TCP, 8.8.8.4, 8080, 8.8.8.8, 8070)
where:
(protocol, local address, local port, remote address, remote port)
Regarding your question (b), be aware that the Websocket specification hasn't been finalised. According to the W3C:
Implementors should be aware that this specification is not stable.
Personally I regard Websockets to be waaay too bleeding edge to use at present. Though I'll probably find them useful in a year or so.
I've been reading up on basic network programming, but am having a difficult time finding a straight-forward explanation for what exactly and socket is, and how it relates to either the OSI or TCP/IP stack.
Can someone explain to me what a socket is? Is it a programmer- or API-defined data structure, or is it a hardware device on a network card?
What layers of the mentioned network models deal with "raw" sockets? Transport layer? Network layer?
In terms of the data they pass between them, are socket text-based or binary?
Is there an alternative to sockets-based network programming? Or do all networked applications use some form of socket?
If I can get this much I should have a pretty clear understanding of everything else I'm reading. Thanks for any help!
Short answers:
Socket is an abstraction of an IP connection endpoint - so if you think of it as an API structure, you are not very far off. Please do read http://en.wikipedia.org/wiki/Internet_socket
Internet layer i.e. IP Protocol. In practice you usually use explicitly sockets that bind to a certain transport layer parameters (datagram/UDP or stream/TCP)
Sockets send data, in network byte order - whether it is text or binary, depends on the upper layer protocol.
Theoretically, probably yes - but in practice all IP traffic is done using 'sockets'
Socket is a software mechanism provided by the operating system. Like its name implies, you can think of it like an "electrical outlet" or some electrical connector, even though socket is not a physical device, but a software mechanism. In real world when you have two electrical connectors, you can connect them with a wire. In the same way in network programming you can create one socket on one computer and another socket on another computer and then connect those sockets. And when you write data to one of them, you receive it on the other one. There are also a few different kinds of sockets. For example if you are programming a server software, you want to have a listening socket which never sends or receives actual data but only listens for and accepts incoming connections and creates a new socket for each new connection.
A socket, in C parlance, is a data structure in kernel space, corresponding to one end-point of a UDP or TCP session (I am using session very loosely when talking about UDP). It's normally associated with one single port number on the local side and seldom more than one "well-known" number on either side of the session.
A "raw socket" is an end-point on, more or less, the physical transport. They're seldom used in applications programming, but sometimes used for various diagnostic things (traceroute, ping, possibly others) and may required elevated privileges to open.
Sockets are, in their nature, a binary octet-transport. It is not uncommon to treat sockets (TCP sockets, at least) as being text-based streams.
I have not yet seen a programming model that doesn't involve something like sockets, if you dig deep enough, but there have certainly been other models of doing networking. The "/net/" pseudo-filesystem, where opening "/net/127.0.0.0.1/tcp/80" (or "tcp/www") would give you a file handle where writes end up on a web server on localhost is but one.
Suppose your PC at home, and you have two browser windows open.
One looking at the facebook website, and the other at the Yahoo website.
The connection to facebook would be:
Your PC – IP1+port 30200 ——– facebook IP2 +port 80 (standard port)
The combination IP1+30200 = the socket on the client computer and IP2 + port 80 = destination socket on the facebook server.
The connection to Yahoo would be:
your PC – IP1+port 60401 ——–Yahoo IP3 +port 80 (standard port)
The combination IP1+60401 = the socket on the client computer andIP3 + port 80 = destination socket on the Yahoo server.
Which is the best solution to communicate bidirectionally between a
remote server and a client behind an internet box?
UPnP with Sockets.
HTTPS/Database Server and the client make 1 request every Xsec to know
if there is new data.
Client opens 1 connection on the server and it maintains open to make a
tunnel.
It totally depends on the application (though you can immediately rule out UPnP, which is an ugly hack suitable for local networks only.) Start reading about the Internet foundation set of protocols - the TCP/IP, pick up the Stevens book - you will get a much better understanding of your options.