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Socket 통신이란

Return a triple (hostname, aliaslist, ipaddrlist) where hostname is the primary host name responding to the given ip_address, aliaslist is a (possibly empty) list of alternative host names for the same address, and ipaddrlist is a list of IPv4/v6 addresses for the same interface on the same host (most likely containing only a single address). To find the fully qualified domain name, use the function getfqdn(). gethostbyaddr() supports both IPv4 and IPv6.关于TCP服务器最大并发连接数有一种误解就是“因为端口号上限为65535,所以TCP服务器理论上的可承载的最大并发连接数也是65535”。首先需要理解一条TCP连接的组成部分:客户端IP、客户端端口、服务端IP、服务端端口。所以对于TCP服务端进程来说,他可以同时连接的客户端数量并不受限于可用端口号,理论上一个服务器的一个端口能建立的连接数是全球的IP数*每台机器的端口数。实际并发连接数受限于linux可打开文件数,这个数是可以配置的,可以非常大,所以实际上受限于系统性能。通过#ulimit -n 查看服务的最大文件句柄数,通过ulimit -n xxx 修改 xxx是你想要能打开的数量。也可以通过修改系统参数:var io = require('socket.io').listen(80); io.sockets.on('connection', function (socket) { socket.emit('news', { hello: 'world' }); socket.on('my other event', function (data) { console.log(data); }); }); client:

A socket object can be in one of three modes: blocking, non-blocking, or timeout. Sockets are by default always created in blocking mode, but this can be changed by calling setdefaulttimeout(). I also noticed that in my program if I changed from socket.emit to socket.send, the server receives a message, but it seems to receive it multiple times. When I use console.log() to see what the server.. German socket (a.k.a Schuko socket or plug Type-F). The earth pins are the clips on both sides. In France the power socket is similar to the German type except that the earth pin is coming out of the.. A socket of type ZMQ_ROUTER is an advanced pattern used for extending request/reply sockets. When receiving messages a ZMQ_ROUTER socket shall prepend a message part containing the identity of the originating peer to the message before passing it to the application. Messages received are fair-queued from among all connected peers. When sending messages a ZMQ_ROUTER socket shall remove the first part of the message and use it to determine the identity of the peer the message shall be routed to. If the peer does not exist anymore the message shall be silently discarded.

Video: CPU socket - Wikipedi

GitHub - socketio/socket

  1. Convert 32-bit positive integers from host to network byte order. On machines where the host byte order is the same as network byte order, this is a no-op; otherwise, it performs a 4-byte swap operation.
  2. g connections when Tcl has an event loop running
  3. On POSIX platforms the SO_REUSEADDR socket option is set in order to immediately reuse previous sockets which were bound on the same address and remained in TIME_WAIT state.
  4. Set blocking or non-blocking mode of the socket: if flag is false, the socket is set to non-blocking, else to blocking mode.
  5. socket 通信技术就是两台联网的计算机之间交换数据的技术,这就是 socket 的全部内容了吗?是的!socket 编程远比想象中的简单很多,阅读完这套简明的入门教程你就能胜任简单的 socket 编程了。
  6. Return the socket’s own address. This is useful to find out the port number of an IPv4/v6 socket, for instance. (The format of the address returned depends on the address family — see above.)

1. Overview. The term socket programming refers to writing programs that execute across multiple computers in which the devices are all connected to each other using a network Return True if the platform supports creating a TCP socket which can handle both IPv4 and IPv6 connections.Build a pair of connected socket objects using the given address family, socket type, and protocol number. Address family, socket type, and protocol number are as for the socket() function above. The default family is AF_UNIX if defined on the platform; otherwise, the default is AF_INET.Supported values for address_family are currently AF_INET and AF_INET6. If the bytes object packed_ip is not the correct length for the specified address family, ValueError will be raised. OSError is raised for errors from the call to inet_ntop().

socket — Low-level networking interface — Python 3

  1. Return the total length, without trailing padding, of an ancillary data item with associated data of the given length. This value can often be used as the buffer size for recvmsg() to receive a single item of ancillary data, but RFC 3542 requires portable applications to use CMSG_SPACE() and thus include space for padding, even when the item will be the last in the buffer. Raises OverflowError if length is outside the permissible range of values.
  2. >>> socket.getaddrinfo("example.org", 80, proto=socket.IPPROTO_TCP) [(<AddressFamily.AF_INET6: 10>, <SocketType.SOCK_STREAM: 1>, 6, '', ('2606:2800:220:1:248:1893:25c8:1946', 80, 0, 0)), (<AddressFamily.AF_INET: 2>, <SocketType.SOCK_STREAM: 1>, 6, '', ('93.184.216.34', 80))] Changed in version 3.2: parameters can now be passed using keyword arguments.
  3. Send normal and ancillary data to the socket, gathering the non-ancillary data from a series of buffers and concatenating it into a single message. The buffers argument specifies the non-ancillary data as an iterable of bytes-like objects (e.g. bytes objects); the operating system may set a limit (sysconf() value SC_IOV_MAX) on the number of buffers that can be used. The ancdata argument specifies the ancillary data (control messages) as an iterable of zero or more tuples (cmsg_level, cmsg_type, cmsg_data), where cmsg_level and cmsg_type are integers specifying the protocol level and protocol-specific type respectively, and cmsg_data is a bytes-like object holding the associated data. Note that some systems (in particular, systems without CMSG_SPACE()) might support sending only one control message per call. The flags argument defaults to 0 and has the same meaning as for send(). If address is supplied and not None, it sets a destination address for the message. The return value is the number of bytes of non-ancillary data sent.
  4. istic behavior, as Python uses the first address returned from the DNS resolution. The socket address will be resolved differently into an actual IPv4/v6 address, depending on the results from DNS resolution and/or the host configuration. For deter
  5. Start listening for socket events from Sails with the specified eventName. Triggers the provided callback function when a matching event is received.
  6. The pipeline pattern is used for distributing data to nodes arranged in a pipeline. Data always flows down the pipeline, and each stage of the pipeline is connected to at least one node. When a pipeline stage is connected to multiple nodes data is round-robined among all connected nodes.

Convert a packed IP address (a bytes-like object of some number of bytes) to its standard, family-specific string representation (for example, '7.10.0.5' or '5aef:2b::8'). inet_ntop() is useful when a library or network protocol returns an object of type struct in_addr (similar to inet_ntoa()) or struct in6_addr.Sockets are automatically closed when they are garbage-collected, but it is recommended to close() them explicitly, or to use a with statement around them.

In timeout mode, operations fail if they cannot be completed within the timeout specified for the socket (they raise a timeout exception) or if the system returns an error. Introducing WebSockets: Bringing Sockets to the Web. Socket.IO 有一部分是伪Socket,是为了兼容传统浏览器的而设计出来的,与真正的 WebSocket 有一定的区别

Return a list of network interface information (index int, name string) tuples. OSError if the system call fails. shutdown is currently (v1.3.0) not properly implemented. (see lwip/src/api/sockets.c:lwip_shutdown()). Socket API. BSD Sockets Interface Programmer's Guide. Categories: LwIP Application Developers Manual. Community content is available under CC-BY-SA unless otherwise noted 第一次握手:建立连接。客户端发送连接请求报文段,将SYN位置为1,Sequence Number为x;然后,客户端进入SYN_SEND状态,等待服务器的确认;第二次握手:服务器收到客户端的SYN报文段,需要对这个SYN报文段进行确认,设置Acknowledgment Number为x+1(Sequence Number+1);同时,自己自己还要发送SYN请求信息,将SYN位置为1,Sequence Number为y;服务器端将上述所有信息放到一个报文段(即SYN+ACK报文段)中,一并发送给客户端,此时服务器进入SYN_RECV状态;第三次握手:客户端收到服务器的SYN+ACK报文段。然后将Acknowledgment Number设置为y+1,向服务器发送ACK报文段,这个报文段发送完毕以后,客户端和服务器端都进入ESTABLISHED状态,完成TCP三次握手。 In the table below, we list all sockets used by CPUs targeted to the mobile market. Pinouts marked with an asterisk don't use a socket; the CPU is soldered directly on the motherboard Translate an Internet port number and protocol name to a service name for that service. The optional protocol name, if given, should be 'tcp' or 'udp', otherwise any protocol will match.

node.js - socket.emit() vs. socket.send() - Stack Overflo

zmq_socket(3) - 0MQ Ap

什么时候用长连接,短连接?长连接多用于操作频繁,点对点的通讯,而且连接数不能太多情况,。每个TCP连接都需要三步握手,这需要时间,如果每个操作都是先连接,再操作的话那么处理 速度会降低很多,所以每个操作完后都不断开,次处理时直接发送数据包就OK了,不用建立TCP连接。例如:数据库的连接用长连接, 如果用短连接频繁的通信会造成Socket错误,而且频繁的Socket创建也是对资源的浪费。The return value is a 4-tuple: (data, ancdata, msg_flags, address). The data item is a bytes object holding the non-ancillary data received. The ancdata item is a list of zero or more tuples (cmsg_level, cmsg_type, cmsg_data) representing the ancillary data (control messages) received: cmsg_level and cmsg_type are integers specifying the protocol level and protocol-specific type respectively, and cmsg_data is a bytes object holding the associated data. The msg_flags item is the bitwise OR of various flags indicating conditions on the received message; see your system documentation for details. If the receiving socket is unconnected, address is the address of the sending socket, if available; otherwise, its value is unspecified.close() releases the resource associated with a connection but does not necessarily close the connection immediately. If you want to close the connection in a timely fashion, call shutdown() before close(). Loading… Log in Sign up current community Stack Overflow help chat Meta Stack Overflow your communities Sign up or log in to customize your list. more stack exchange communities company blog By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Service. A socket of type ZMQ_PAIR can only be connected to a single peer at any one time. No message routing or filtering is performed on messages sent over a ZMQ_PAIR socket.

一篇搞懂TCP、HTTP、Socket、Socket - SegmentFault 思

  1. If the byte sequence passed to this function is not exactly 4 bytes in length, OSError will be raised. inet_ntoa() does not support IPv6, and inet_ntop() should be used instead for IPv4/v6 dual stack support.
  2. 文章不深奥,不需要钻研,在公交、在地铁、在厕所都可以阅读,随时随地涨姿势。
  3. Check your need for a power plug (travel) adapter in South Korea. In South Korea the power plugs and sockets are of type C and F. The standard voltage is 220 V and the frequency is 60 Hz
  4. Changed in version 3.2: The returned socket objects now support the whole socket API, rather than a subset.
  5. Receive normal data (up to bufsize bytes) and ancillary data from the socket. The ancbufsize argument sets the size in bytes of the internal buffer used to receive the ancillary data; it defaults to 0, meaning that no ancillary data will be received. Appropriate buffer sizes for ancillary data can be calculated using CMSG_SPACE() or CMSG_LEN(), and items which do not fit into the buffer might be truncated or discarded. The flags argument defaults to 0 and has the same meaning as for recv().
  6. Currently only the following control codes are supported: SIO_RCVALL, SIO_KEEPALIVE_VALS, and SIO_LOOPBACK_FAST_PATH.
  7. const client = new net.Socket(); client.connect(9000, '127.0.0.1', function () { }); client.on('data', (chunk) => { console.log('data', chunk.toString()) //data Hi! //Bye! }); Socket长连接 所谓长连接,指在一个TCP连接上可以连续发送多个数据包,在TCP连接保持期间,如果没有数据包发送,需要双方发检测包以维持此连接(心跳包),一般需要自己做在线维持。 短连接是指通信双方有数据交互时,就建立一个TCP连接,数据发送完成后,则断开此TCP连接。比如Http的,只是连接、请求、关闭,过程时间较短,服务器若是一段时间内没有收到请求即可关闭连接。其实长连接是相对于通常的短连接而说的,也就是长时间保持客户端与服务端的连接状态。 通常的短连接操作步骤是: 连接→数据传输→关闭连接;

socket编程入门:1天玩转socket通信技术(非常详细

socket(2) - Linux manual pag

  1. ​ 关于传输层TCP、UDP协议可能我们平时遇见的会比较多,有人说TCP是安全的,UDP是不安全的,UDP传输比TCP快,那为什么呢,我们先从TCP的连接建立的过程开始分析,然后解释UDP和TCP的区别。
  2. The address of an AF_UNIX socket bound to a file system node is represented as a string, using the file system encoding and the 'surrogateescape' error handler (see PEP 383). An address in Linux’s abstract namespace is returned as a bytes-like object with an initial null byte; note that sockets in this namespace can communicate with normal file system sockets, so programs intended to run on Linux may need to deal with both types of address. A string or bytes-like object can be used for either type of address when passing it as an argument.
  3. Convert 16-bit positive integers from network to host byte order. On machines where the host byte order is the same as network byte order, this is a no-op; otherwise, it performs a 2-byte swap operation.

Timeouts and the connect method¶

socket.io/2.3./socket.io.slim.js.map. Related Tutorials TL;DR — nuxt-socket-io is a module for the Nuxt framework that allows you to co... Tagged with Introduction to Nuxt Socket.IO. Richard Schloss. Nov 22 '19 Originally published at Medium on Oct 22.. If you notice something we've missed or could be improved on, please follow this link and submit a pull request to the sails-docs repo. Once we merge it, the changes will be reflected on the website the next time it is deployed.

io.socket.on(

If supplied, source_address must be a 2-tuple (host, port) for the socket to bind to as its source address before connecting. If host or port are ‘’ or 0 respectively the OS default behavior will be used. 45 TL;DR:The following sections present the socket types defined by ØMQ, grouped by the general messaging pattern which is built from related socket types.

Video: IC Burn in socket adapter manufacturer ANDK KZT HMILU IC test

Socket 编程 · 笔试面试知识整

Socket Programming in C/C++ - GeeksforGeek

Return the default timeout in seconds (float) for new socket objects. A value of None indicates that new socket objects have no timeout. When the socket module is first imported, the default is None.When a ZMQ_DEALER socket is connected to a ZMQ_REP socket each message sent must consist of an empty message part, the delimiter, followed by one or more body parts.

Timeouts and the accept method¶

客户端建立连接 ::ffff:127.0.0.1:50178 content: length:0000000000031 20 length 31 heap.length 0 content: "Tue, 03 Apr 2018 06:12:37 GMT" 31 heap.length 31 收到数据 Tue, 03 Apr 2018 06:12:37 GMT broadcast heartbeat 1 content: HeartBeat 9 收到客户端发过来的一个心跳包 content: length:0000000000031"Tue, 03 Apr 2018 06:12:42 GMT" 51 length 31 heap.length 31 收到数据 Tue, 03 Apr 2018 06:12:42 GMT 客户端 从另外一个角度讲,它是将BSD socket的接口的每个函数都让用户可以通过界面进行独立的调用。 比如用于TCP连接的connect,变为连接按钮;比如发送数据的send函数变为发送按钮 BTPROTO_L2CAP accepts (bdaddr, psm) where bdaddr is the Bluetooth address as a string and psm is an integer.addr - Optional bytes-like object specifying the hardware physical address, whose interpretation depends on the device.Changed in version 3.5: The socket timeout is no more reset each time data is sent successfully. The socket timeout is now the maximum total duration to send all data.

Closing the file object returned by makefile() won’t close the original socket unless all other file objects have been closed and socket.close() has been called on the socket object.Create a new socket using the given address family, socket type and protocol number. The address family should be AF_INET (the default), AF_INET6, AF_UNIX, AF_CAN, AF_PACKET, or AF_RDS. The socket type should be SOCK_STREAM (the default), SOCK_DGRAM, SOCK_RAW or perhaps one of the other SOCK_ constants. The protocol number is usually zero and may be omitted or in the case where the address family is AF_CAN the protocol should be one of CAN_RAW, CAN_BCM or CAN_ISOTP.The publish-subscribe pattern is used for one-to-many distribution of data from a single publisher to multiple subscribers in a fan out fashion.

​ 首先从网络通信的分层模型讲起:七层模型,亦称OSI(Open System Interconnection)模型。自下往上分为:物理层、数据链路层、网络层、传输层、会话层、表示层和应用层。所有有关通信的都离不开它,下面这张图片介绍了各层所对应的一些协议和硬件

Socket (Java Platform SE 7

Set the default timeout in seconds (float) for new socket objects. When the socket module is first imported, the default is None. See settimeout() for possible values and their respective meanings.AF_VSOCK allows communication between virtual machines and their hosts. The sockets are represented as a (CID, port) tuple where the context ID or CID and port are integers.

CAN_BCM, in the CAN protocol family, is the broadcast manager (BCM) protocol. Broadcast manager constants, documented in the Linux documentation, are also defined in the socket module. socket 是“套接字”的意思,学习 socket 编程,也就是学习计算机之间如何通信,并用编程语言来实现它。Constants for Windows’ WSAIoctl(). The constants are used as arguments to the ioctl() method of socket objects.

Sockets - Servers - Kto

Specialized version of sendmsg() for AF_ALG socket. Set mode, IV, AEAD associated data length and flags for AF_ALG socket.sendMessage: function(type, message) { socket.emit('message', { type: type, message: message }); } and for those keeping score at home, here is what it looks like using socket.send: 什么是心跳包为什么需要:心跳包就是在客户端和服务端间定时通知对方自己状态的一个自己定义的命令字,按照一定的时间间隔发送,类似于心跳,所以叫做心跳包。网络中的接收和发送数据都是使用Socket进行实现。但是如果此套接字已经断开(比如一方断网了),那发送数据和接收数据的时候就一定会有问题。可是如何判断这个套接字是否还可以使用呢?这个就需要在系统中创建心跳机制。其实TCP中已经为我们实现了一个叫做心跳的机制。如果你设置了心跳,那TCP就会在一定的时间(比如你设置的是3秒钟)内发送你设置的次数的心跳(比如说2次),并且此信息不会影响你自己定义的协议。也可以自己定义,所谓“心跳”就是定时发送一个自定义的结构体(心跳包或心跳帧),让对方知道自己“在线”,以确保链接的有效性。实现:服务端:Connect to a TCP service listening on the Internet address (a 2-tuple (host, port)), and return the socket object. This is a higher-level function than socket.connect(): if host is a non-numeric hostname, it will try to resolve it for both AF_INET and AF_INET6, and then try to connect to all possible addresses in turn until a connection succeeds. This makes it easy to write clients that are compatible to both IPv4 and IPv6. include <sys/socket.h>. int socket(int domain, int type, int protocol); DESCRIPTION top. socket() creates an endpoint for communication and returns a file. descriptor that refers to that endpoint

socket.io - np

The family, type and proto arguments can be optionally specified in order to narrow the list of addresses returned. Passing zero as a value for each of these arguments selects the full range of results. The flags argument can be one or several of the AI_* constants, and will influence how results are computed and returned. For example, AI_NUMERICHOST will disable domain name resolution and will raise an error if host is a domain name.sock = socket.socket( socket.AF_INET, socket.SOCK_STREAM | socket.SOCK_NONBLOCK) will still create a non-blocking socket on OSes that support SOCK_NONBLOCK, but sock.type will be set to socket.SOCK_STREAM.In these tuples, family, type, proto are all integers and are meant to be passed to the socket() function. canonname will be a string representing the canonical name of the host if AI_CANONNAME is part of the flags argument; else canonname will be empty. sockaddr is a tuple describing a socket address, whose format depends on the returned family (a (address, port) 2-tuple for AF_INET, a (address, port, flow info, scope id) 4-tuple for AF_INET6), and is meant to be passed to the socket.connect() method.

Unix Socket - Server Examples - Tutorialspoin

  1. Return a network interface index number corresponding to an interface name. OSError if no interface with the given name exists.
  2. The exclusive pair pattern is used to connect a peer to precisely one other peer. This pattern is used for inter-thread communication across the inproc transport.
  3. 什么是Socket连接池,池的概念可以联想到是一种资源的集合,所以Socket连接池,就是维护着一定数量Socket长连接的集合。它能自动检测Socket长连接的有效性,剔除无效的连接,补充连接池的长连接的数量。从代码层次上其实是人为实现这种功能的类,一般一个连接池包含下面几个属性:
  4. Set the value of the given socket option (see the Unix manual page setsockopt(2)). The needed symbolic constants are defined in the socket module (SO_* etc.). The value can be an integer, None or a bytes-like object representing a buffer. In the later case it is up to the caller to ensure that the bytestring contains the proper bits (see the optional built-in module struct for a way to encode C structures as bytestrings). When value is set to None, optlen argument is required. It’s equivalent to call setsockopt() C function with optval=NULL and optlen=optlen.
  5. Deprecated since version 3.7: In case x does not fit in 16-bit unsigned integer, but does fit in a positive C int, it is silently truncated to 16-bit unsigned integer. This silent truncation feature is deprecated, and will raise an exception in future versions of Python.
  6. These constants represent the socket types, used for the second argument to socket(). More constants may be available depending on the system. (Only SOCK_STREAM and SOCK_DGRAM appear to be generally useful.)
  7. 这套 socket 入门教程需要读者具备C语言基础,如果你还不了解C语言,请转到《C语言入门教程》。

CPU Socket Types Explained: Socket 5 to BG

  1. import socket import struct # CAN frame packing/unpacking (see 'struct can_frame' in <linux/can.h>) can_frame_fmt = "=IB3x8s" can_frame_size = struct.calcsize(can_frame_fmt) def build_can_frame(can_id, data): can_dlc = len(data) data = data.ljust(8, b'\x00') return struct.pack(can_frame_fmt, can_id, can_dlc, data) def dissect_can_frame(frame): can_id, can_dlc, data = struct.unpack(can_frame_fmt, frame) return (can_id, can_dlc, data[:can_dlc]) # create a raw socket and bind it to the 'vcan0' interface s = socket.socket(socket.AF_CAN, socket.SOCK_RAW, socket.CAN_RAW) s.bind(('vcan0',)) while True: cf, addr = s.recvfrom(can_frame_size) print('Received: can_id=%x, can_dlc=%x, data=%s' % dissect_can_frame(cf)) try: s.send(cf) except OSError: print('Error sending CAN frame') try: s.send(build_can_frame(0x01, b'\x01\x02\x03')) except OSError: print('Error sending CAN frame') Running an example several times with too small delay between executions, could lead to this error:
  2. For IPv6 addresses, %scope is appended to the host part if sockaddr contains meaningful scopeid. Usually this happens for multicast addresses.
  3. These are string constants containing Bluetooth addresses with special meanings. For example, BDADDR_ANY can be used to indicate any address when specifying the binding socket with BTPROTO_RFCOMM.
  4. Previously this socket was called ZMQ_XREP and that name remains available for backwards compatibility.
  5. Sockets. This functionality is exposed through the io.ktor:ktor-network:$ktor_version artifact. In order to create either server or client sockets, you have to use the aSocket builder, with a mandatory..
  6. A socket of type ZMQ_REQ is used by a client to send requests to and receive replies from a service. This socket type allows only an alternating sequence of zmq_send(request) and subsequent zmq_recv(reply) calls. Each request sent is round-robined among all services, and each reply received is matched with the last issued request.

This is a Python type object that represents the socket object type. It is the same as type(socket(...)).I noticed that if I changed from socket.emit to socket.send in a working program, the server failed to receive the message, although I don't understand why.var io = require('socket.io').listen(80); io.sockets.on('connection', function (socket) { socket.send('hi'); }); client:Like connect(address), but return an error indicator instead of raising an exception for errors returned by the C-level connect() call (other problems, such as “host not found,” can still raise exceptions). The error indicator is 0 if the operation succeeded, otherwise the value of the errno variable. This is useful to support, for example, asynchronous connects.

Socket - Handbook Mbe

WebSocket.onopen - Web APIs MD

both in the UNIX Programmer’s Manual, Supplementary Documents 1 (sections PS1:7 and PS1:8). The platform-specific reference material for the various socket-related system calls are also a valuable source of information on the details of socket semantics. For Unix, refer to the manual pages; for Windows, see the WinSock (or Winsock 2) specification. For IPv6-ready APIs, readers may want to refer to RFC 3493 titled Basic Socket Interface Extensions for IPv6.A socket of type ZMQ_REP is used by a service to receive requests from and send replies to a client. This socket type allows only an alternating sequence of zmq_recv(request) and subsequent zmq_send(reply) calls. Each request received is fair-queued from among all clients, and each reply sent is routed to the client that issued the last request. If the original requester doesn't exist any more the reply is silently discarded.The following example fetches address information for a hypothetical TCP connection to example.org on port 80 (results may differ on your system if IPv6 isn’t enabled):var socket = io.connect('http://localhost'); socket.on('news', function (data) { console.log(data); socket.emit('my other event', { my: 'data' }); }); Socket.send does the same, but you don't register to 'news' but to message:Return the remote address to which the socket is connected. This is useful to find out the port number of a remote IPv4/v6 socket, for instance. (The format of the address returned depends on the address family — see above.) On some systems this function is not supported.

A string or a tuple (id, unit) is used for the SYSPROTO_CONTROL protocol of the PF_SYSTEM family. The string is the name of a kernel control using a dynamically-assigned ID. The tuple can be used if ID and unit number of the kernel control are known or if a registered ID is used.Send data to the socket. The socket should not be connected to a remote socket, since the destination socket is specified by address. The optional flags argument has the same meaning as for recv() above. Return the number of bytes sent. (The format of address depends on the address family — see above.) SOCKET.IO یکی از کتابخانه های جاوا اسکریپت است که یک ارتباط دو طرفه بین کلاینت و سرور برقرار می کند! Socket.IO چیست ؟ شروع کار با آن. بلاگ آکادمی لرن فایلز 客户端建立连接: ::ffff:127.0.0.1:57125 broadcast heartbeat 1 收到客户端发过来的数据: Thu, 29 Mar 2018 03:45:15 GMT 收到客户端发过来的一个心跳包 收到客户端发过来的数据: Thu, 29 Mar 2018 03:45:20 GMT broadcast heartbeat 1 收到客户端发过来的数据: Thu, 29 Mar 2018 03:45:25 GMT 收到客户端发过来的一个心跳包 客户端建立连接: ::ffff:127.0.0.1:57129 收到客户端发过来的一个心跳包 收到客户端发过来的数据: Thu, 29 Mar 2018 03:46:00 GMT 收到客户端发过来的数据: Thu, 29 Mar 2018 03:46:04 GMT broadcast heartbeat 2 收到客户端发过来的数据: Thu, 29 Mar 2018 03:46:05 GMT 收到客户端发过来的一个心跳包 客户端代码:If the IPv4 address string passed to this function is invalid, OSError will be raised. Note that exactly what is valid depends on the underlying C implementation of inet_aton().

简单理解Socket - 谦行 - 博客

A socket of type ZMQ_DEALER is an advanced pattern used for extending request/reply sockets. Each message sent is round-robined among all connected peers, and each message received is fair-queued from all connected peers.关于TCP/IP和HTTP协议的关系,网络有一段比较容易理解的介绍:“我们在传输数据时,可以只使用(传输层)TCP/IP协议,但是那样的话,如果没有应用层,便无法识别数据内容。如果想要使传输的数据有意义,则必须使用到应用层协议。应用层协议有很多,比如HTTP、FTP、TELNET等,也可以自己定义应用层协议。HTTP协议即超文本传送协议(Hypertext Transfer Protocol ),是Web联网的基础,也是手机联网常用的协议之一,WEB使用HTTP协议作应用层协议,以封装HTTP文本信息,然后使用TCP/IP做传输层协议将它发到网络上。由于HTTP在每次请求结束后都会主动释放连接,因此HTTP连接是一种“短连接”,要保持客户端程序的在线状态,需要不断地向服务器发起连接请求。通常 的做法是即时不需要获得任何数据,客户端也保持每隔一段固定的时间向服务器发送一次“保持连接”的请求,服务器在收到该请求后对客户端进行回复,表明知道 客户端“在线”。若服务器长时间无法收到客户端的请求,则认为客户端“下线”,若客户端长时间无法收到服务器的回复,则认为网络已经断开。下面是一个简单的HTTP Post application/json数据内容的请求:if the listening socket is in non-blocking mode, whether the socket returned by accept() is in blocking or non-blocking mode is operating system-dependent. If you want to ensure cross-platform behaviour, it is recommended you manually override this setting.Changed in version 3.2: Support for the context manager protocol was added. Exiting the context manager is equivalent to calling close().Instantiate a socket from data obtained from the socket.share() method. The socket is assumed to be in blocking mode.

If the connection is interrupted by a signal, the method waits until the connection completes, or raise a socket.timeout on timeout, if the signal handler doesn’t raise an exception and the socket is blocking or has a timeout. For non-blocking sockets, the method raises an InterruptedError exception if the connection is interrupted by a signal (or the exception raised by the signal handler). Realtime application framework (Node.JS server). Contribute to socketio/socket.io development by creating an account on GitHub

In computer hardware, a CPU socket or CPU slot contains one or more mechanical components providing mechanical and electrical connections between a microprocessor and a printed circuit board.. Library: Net Package: Sockets Header: Poco/Net/Socket.h. Socket is the common base class for StreamSocket, ServerSocket, DatagramSocket and other socket classes

std.socket - D Programming Languag

For AF_INET6 address family, a four-tuple (host, port, flowinfo, scopeid) is used, where flowinfo and scopeid represent the sin6_flowinfo and sin6_scope_id members in struct sockaddr_in6 in C. For socket module methods, flowinfo and scopeid can be omitted just for backward compatibility. Note, however, omission of scopeid can cause problems in manipulating scoped IPv6 addresses.Translate an Internet service name and protocol name to a port number for that service. The optional protocol name, if given, should be 'tcp' or 'udp', otherwise any protocol will match.

| socket — Low-level networking interface¶. Source code: Lib/socket.py. The address format required by a particular socket object is automatically selected based on the address family specified.. When a ZMQ_REQ socket is connected to a ZMQ_ROUTER socket, in addition to the identity of the originating peer each message received shall contain an empty delimiter message part. Hence, the entire structure of each received message as seen by the application becomes: one or more identity parts, delimiter part, one or more body parts. When sending replies to a ZMQ_REQ socket the application must include the delimiter part.

Constant for Qualcomm’s IPC router protocol, used to communicate with service providing remote processors.Connect to a remote socket at address. (The format of address depends on the address family — see above.) Socket programming is a way of connecting two nodes on a network to communicate with each sockfd: socket descriptor, an integer (like a file-handle) domain: integer, communication domain e.g.. A subclass of OSError, this exception is raised when a timeout occurs on a socket which has had timeouts enabled via a prior call to settimeout() (or implicitly through setdefaulttimeout()). The accompanying value is a string whose value is currently always “timed out”.const net = require('net'); const server = net.createServer(); server.on('connection', (client) => { client.write('Hi!\n'); // 服务端向客户端输出信息,使用 write() 方法 client.write('Bye!\n'); //client.end(); // 服务端结束该次会话 }); server.listen(9000); 服务监听9000端口下面使用命令行发送http请求和telnet

Socket is a local phone and internet service provider, dedicated to serving Missouri homes and businesses since 1994. Socket has the right combination of services to fit your size and budget ..REAL-TIME ENGINE ~/Projects/tweets/index.js var io = socket.io Unix Socket - Server Examples - To make a process a TCP server, you need to follow the steps given below −

In non-blocking mode, operations fail (with an error that is unfortunately system-dependent) if they cannot be completed immediately: functions from the select can be used to know when and whether a socket is available for reading or writing.Receive data from the socket. The return value is a bytes object representing the data received. The maximum amount of data to be received at once is specified by bufsize. See the Unix manual page recv(2) for the meaning of the optional argument flags; it defaults to zero.

精美而实用的网站,分享优质编程教程,帮助编程初学者。千锤百炼,只为大作;精益求精,句句斟酌;这种教程,看一眼就倾心。$ curl http://127.0.0.1:9000 Bye! $telnet 127.0.0.1 9000 Trying 192.168.1.21... Connected to 192.168.1.21. Escape character is '^]'. Hi! Bye! Connection closed by foreign host. 注意到curl只处理了一次报文。客户端

第一次分手:主机1(可以使客户端,也可以是服务器端),设置Sequence Number和Acknowledgment Number,向主机2发送一个FIN报文段;此时,主机1进入FIN_WAIT_1状态;这表示主机1没有数据要发送给主机2了;第二次分手:主机2收到了主机1发送的FIN报文段,向主机1回一个ACK报文段,Acknowledgment Number为Sequence Number加1;主机1进入FIN_WAIT_2状态;主机2告诉主机1,我“同意”你的关闭请求;第三次分手:主机2向主机1发送FIN报文段,请求关闭连接,同时主机2进入LAST_ACK状态;第四次分手:主机1收到主机2发送的FIN报文段,向主机2发送ACK报文段,然后主机1进入TIME_WAIT状态;主机2收到主机1的ACK报文段以后,就关闭连接;此时,主机1等待2MSL后依然没有收到回复,则证明Server端已正常关闭,那好,主机1也可以关闭连接了。When a ZMQ_REQ socket enters an exceptional state due to having reached the high water mark for all services, or if there are no services at all, then any zmq_send(3) operations on the socket shall block until the exceptional state ends or at least one service becomes available for sending; messages are not discarded. socket_pool 127.0.0.1 9000 connect socket_pool 127.0.0.1 9000 connect content length:0000000000040"服务端的数据数据:{\"a\":\"a\"}" 44 length 40 heap.length 40 收到服务的数据 服务端的数据数据:{"a":"a"} content length:0000000000040"服务端的数据数据:{\"b\":\"b\"}" 44 length 40 heap.length 40 收到服务的数据 服务端的数据数据:{"b":"b"} content length:0000000000040 20 length 40 heap.length 0 content "服务端的数据数据:{\"c\":\"c\"}" 24 heap.length 40 收到服务的数据 服务端的数据数据:{"c":"c"} content length:0000000000040"服务端的数据数据:{\"d\":\"d\"}" 44 length 40 heap.length 40 收到服务的数据 服务端的数据数据:{"d":"d"} 这里看到前面两个请求都建立了新的Socket连接 socket_pool 127.0.0.1 9000 connect,定时器结束后重新发起两个请求就没有建立新的Socket连接了,直接从连接池里面获取Socket连接资源。

Computer processor sockets. Below is a short list of sockets and their description we currently The processor socket helps determine what computer processors your computer motherboard is capable.. 发送数据 Thu, 29 Mar 2018 03:46:04 GMT 收到数据: 服务端的数据:Thu, 29 Mar 2018 03:46:04 GMT 收到心跳包: HEARTBEAT 发送数据 Thu, 29 Mar 2018 03:46:09 GMT 收到数据: 服务端的数据:Thu, 29 Mar 2018 03:46:09 GMT 发送数据 Thu, 29 Mar 2018 03:46:14 GMT 收到数据: 服务端的数据:Thu, 29 Mar 2018 03:46:14 GMT 收到心跳包: HEARTBEAT 发送数据 Thu, 29 Mar 2018 03:46:19 GMT 收到数据: 服务端的数据:Thu, 29 Mar 2018 03:46:19 GMT 发送数据 Thu, 29 Mar 2018 03:46:24 GMT 收到数据: 服务端的数据:Thu, 29 Mar 2018 03:46:24 GMT 收到心跳包: HEARTBEAT 定义自己的协议 如果想要使传输的数据有意义,则必须使用到应用层协议比如Http、Mqtt、Dubbo等。基于TCP协议上自定义自己的应用层的协议需要解决的几个问题:Send data to the socket. The socket must be connected to a remote socket. The optional flags argument has the same meaning as for recv() above. Unlike send(), this method continues to send data from bytes until either all data has been sent or an error occurs. None is returned on success. On error, an exception is raised, and there is no way to determine how much data, if any, was successfully sent.

Convert 32-bit positive integers from network to host byte order. On machines where the host byte order is the same as network byte order, this is a no-op; otherwise, it performs a 4-byte swap operation.const net = require('net'); const client = new net.Socket(); const heartBeat = 'HeartBeat'; // 定义心跳包内容确保和平时发送的数据不会冲突 const getHeader = (num) => { return 'length:' + (Array(13).join(0) + num).slice(-13); } client.connect(9000, '127.0.0.1', function () {}); let chunks = []; let length = 0; client.on('data', (chunk) => { let content = chunk.toString(); console.log("content:", content, content.length); if (content === heartBeat) { console.log('收到服务端发过来的一个心跳包'); } else { if (content.indexOf('length:') === 0){ length = parseInt(content.substring(7,20)); console.log('length', length); chunks =[chunk.slice(20, chunk.length)]; } else { chunks.push(chunk); } let heap = Buffer.concat(chunks); console.log('heap.length', heap.length) if (heap.length >= length) { try { console.log('收到数据', JSON.parse(heap.toString())); } catch (err) { console.log('数据解析失败'); } } } }); // 定时发送数据 setInterval(function () { let data = new Date().toUTCString(); let dataBuff = Buffer.from(JSON.stringify(data)); let header =getHeader(dataBuff.length); client.write(header); client.write(dataBuff); }, 5000); // 定时发送心跳包 setInterval(function () { client.write(heartBeat); }, 10000); 日志打印:Return the timeout in seconds (float) associated with socket operations, or None if no timeout is set. This reflects the last call to setblocking() or settimeout(). Socket 起源于 Unix ,Unix/Linux 基本哲学之一就是一切皆文件,都可以用打开(open) -> 读写(write/read) -> 关闭(close) 因此 Socket 也被处理为一种特殊的文件。 写一个简易的 WebServer Consequently, direct usage of the 'connect' event is not necessary for most apps. But in the spirit of completeness, it is worth mentioning that you can also bind your own 'connect' handler:

Quantity 1 = 10 sockets. Each PCB Socket is enough to do 1 switch. Please note that these require a compatible PCB, and will not work on a majority of the PCBs out there const net = require('net'); const heartbeat = 'HEARTBEAT'; const client = new net.Socket(); client.connect(9000, '127.0.0.1', () => {}); client.on('data', (chunk) => { let content = chunk.toString(); if (content === heartbeat) { console.log('收到心跳包:', content); } else { console.log('收到数据:', content); } }); // 定时发送数据 setInterval(() => { console.log('发送数据', new Date().toUTCString()); client.write(new Date().toUTCString()); }, 5000); // 定时发送心跳包 setInterval(function () { client.write(heartbeat); }, 10000); 客户端输出结果:A socket of type ZMQ_PUB is used by a publisher to distribute data. Messages sent are distributed in a fan out fashion to all connected peers. The zmq_recv(3) function is not implemented for this socket type.

Previously this socket was called ZMQ_XREQ and that name remains available for backwards compatibility.When a ZMQ_PAIR socket enters an exceptional state due to having reached the high water mark for the connected peer, or if no peer is connected, then any zmq_send(3) operations on the socket shall block until the peer becomes available for sending; messages are not discarded.场景: 一个请求过来,首先去资源池要求获取一个长连接资源,如果空闲队列里面有长连接,就获取到这个长连接Socket,并把这个Socket移到正在运行的长连接队列。如果空闲队列里面没有,且正在运行的队列长度小于配置的连接池资源的数量,就新建一个长连接到正在运行的队列去,如果正在运行的不下于配置的资源池长度,则这个请求进入到等待队列去。当一个正在运行的Socket完成了请求,就从正在运行的队列移到空闲的队列,并触发等待请求队列去获取空闲资源,如果有等待的情况。

Bind the socket to address. The socket must not already be bound. (The format of address depends on the address family — see above.)可以看到一次tcp请求的建立及关闭至少进行7次通信,这还不包过数据的通信,而UDP不需3次握手和4次分手。Changed in version 3.5: If the system call is interrupted and the signal handler does not raise an exception, the method now retries the system call instead of raising an InterruptedError exception (see PEP 475 for the rationale).

Some systems do not indicate the truncated length of ancillary data items which have been only partially received. If an item appears to extend beyond the end of the buffer, recvmsg() will issue a RuntimeWarning, and will return the part of it which is inside the buffer provided it has not been truncated before the start of its associated data. socket 是套接字的意思,学习 socket 编程,也就是学习计算机之间如何通信,并用编程语言来实现它

name is the algorithm name and operation mode as string, e.g. sha256, hmac(sha256), cbc(aes) or drbg_nopr_ctr_aes256.When a ZMQ_ROUTER socket enters an exceptional state due to having reached the high water mark for all peers, or if there are no peers at all, then any messages sent to the socket shall be dropped until the exceptional state ends. Likewise, any messages routed to a non-existent peer or a peer for which the individual high water mark has been reached shall also be dropped. HTML rendering created 2020-05-27 by Michael Kerrisk, author of The Linux Programming Interface, maintainer of the Linux man-pages project. CAN_ISOTP protocol require a tuple (interface, rx_addr, tx_addr) where both additional parameters are unsigned long integer that represent a CAN identifier (standard or extended).

Shut down one or both halves of the connection. If how is SHUT_RD, further receives are disallowed. If how is SHUT_WR, further sends are disallowed. If how is SHUT_RDWR, further sends and receives are disallowed.Convenience function which creates a TCP socket bound to address (a 2-tuple (host, port)) and return the socket object. From Middle English socket, soket, from Anglo-Norman soket (spearhead), diminutive of Old French soc (plowshare), from Vulgar Latin *soccus, a word borrowed from Gaulish, from Proto-Celtic *sukkos (compare modern Welsh swch (plowshare)), literally pig's snout, from Proto-Indo-European *suH-

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