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  • Socket Communication in C#- IP-Port

    - by Ahmet Altun
    I am testing my socket programs at home, in local network. Server and client programs are running on seperate machines. Server program socket is binded as: serverSocket.Bind(new IPEndPoint(IPAddress.Parse("127.0.0.1"), 8999)); Client program (on the other computer) is connected as: clientSocket.Connect(IPAddress.Parse("192.168.2.3"), 8999); Why can Client not communicate with server? Do I need to make some firewall configuration or something like that? Or am I writing Server Ip incorrectly to the Client? (I got it from cmd-ipconfig of server)

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  • Tcp Socket Closed

    - by Michael Covelli
    I always thought that if you didn't implement a heartbeat, there was no way to know if one side of a TCP connection died unexpectedly. If the process was just killed on one side and didn't exit gracefully, there was no way for the socket to send FIN or let the other side know that it was closed. (See some of the comments here for example http://www.perlmonks.org/?node_id=566568 ) But there is a stock order server that I connect to that has a new "cancel all orders on disconnect feature" that cancels live orders if the client dis-connects. It works even when I kill the process on my end, and there is definitely no heartbeat from my app to it. So how is it able to detect when I've killed the process? My app is running on Windows Server 2003 and the order server is on Suse Linux Enterprise Server 10. Does Windows detect that the process associated with the socket is no longer alive and send the FIN?

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  • Using sys/socket.h functions on windows

    - by BSchlinker
    Hello, I'm attempting to utilize the socket.h functions within Windows. Essentially, I'm currently looking at the sample code at http://beej.us/guide/bgnet/output/html/multipage/clientserver.html#datagram. I understand that socket.h is a Unix function -- is there anyway I can easily emulate that environment while compiling this sample code? Does a different IDE / compiler change anything? Otherwise, I imagine that I need to utilize a virtualized Linux environment, which may be best anyways as the code will most likely be running in a UNIX environment. Thanks.

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  • [Linux] domain socket "sendto" encounter "errno 111, connection refused"

    - by z.cHris
    I am using domain socket to get values from another process, like A to get a value from B, It works well for months. But recently, A is failed during "sendto" message to B with "errno 111, connection refused" occasionally. I checked the B domain socket bind file, it is exists. I also do some tests in another machine, also works well. So, does anyone encounter this problem before? Can anyone have some clues what might be probably wrong in this scenario? Thanks very much.

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  • Python, implementing proxy support for a socket based application (not urllib2)

    - by Terry Felkrow
    Hey guys, I am little stumped: I have a simple messenger client program (pure python, sockets), and I wanted to add proxy support (http/s, socks), however I am a little confused on how to go about it. I am assuming that the connection on the socket level will be done to the proxy server, at which point the headers should contain a CONNECT + destination IP (of the chat server) and authentication, (if proxy requires so), however the rest is a little beyond me. How is the subsequent connection handled, specifically the reading/writing, etc... Are there any guides on proxy support implementation for socket based (tcp) programming in Python? Thank you

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  • Confusion in bind call in socket programming

    - by Tarun
    i was learning socket programming in unix using c/c++. I am confused with one function call bind(params..). Actually it takes the adreess structure "sockaddr_in" and we can create the structure in the following way sockaddr_in.*** = somthing.. sockaddr_in..s_addr htonl(INADDR_ANY) **Passing INADDR_ANY will alow to bind all local addresses** My question is , why do we need to use "INADDR_ANY" ? In my knowledge every machine can has only one unique IP Address. In this way there is only one address associated with the machien. Thye bind call should directly bind the socket to the single available address. Please explain what are the different scenarios and why is it so?

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  • When to use Nginx PHP Fast CGI with a TCP socket instead of a UNIX socket?

    - by user64204
    I've followed this guide to setup PHP in FastCGI mode with Nginx. This guide describes 2 ways of doing it: TCP socket and UNIX socket. I've ran some Apache Benchmark on my locale machine and here are the results: Below tests ran multiple times to get better average statistics: $ ab -c 200 -n 100000 http://.... APACHE: 1800 req/sec NGINX (TCP socket): 2500 req/sec NGINX (UNIX socket): 15000 req/sec As far as I understand, there is overhead with using a TCP socket rather than a UNIX socket, hence the better performance with the latter. However I was not expecting such a performance difference given that the TCP socket is on the localhost, and therefore would like to ask the following question: Q: Given the huge performance gain with using a UNIX socket, what are the configuration scenarios where it would make sense to use a TCP socket instead?

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  • STL algorithms and concurrent programming

    - by Andrew
    Hello everyone, Can any of STL algorithms/container operations like std::fill, std::transform be executed in parallel if I enable OpenMP for my compiler? I am working with MSVC 2008 at the moment. Or maybe there are other ways to make it concurrent? Thanks.

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  • Are we in a functional programming fad?

    - by TraumaPony
    I use both functional and imperative languages daily, and it's rather amusing to see the surge of adoption of functional languages from both sides of the fence. It strikes me, however, that it looks rather like a fad. Do you think that it's a fad? I know the reasons for using functional languages at times and imperative languages in others, but do you really think that this trend will continue due to the cliched "many-core" revolution that has been only "18 months from now" since 2004 (sort of like communism's Radiant Future), or do you think that it's only temporary; a fascination of the mainstream developer that will be quickly replaced by the next shiny idea, like Web 3.0 or GPGPU? Note, that I'm not trying to start a flamewar or anything (sorry if it sounds bitter), I'm just curious as to whether people will think functional or functional/imperative languages will become mainstream. Edit: By mainstream, I mean, equal number of programmers to say, Python, Java, C#, etc

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  • is this possible in java or any other programming language

    - by drake
    public abstract class Master { public void printForAllMethodsInSubClass() { System.out.println ("Printing before subclass method executes"); } } public class Owner extends Master { public void printSomething () { System.out.println ("This printed from Owner"); } public int returnSomeCals () { return 5+5; } } Without messing with methods of subclass...is it possible to execute printForAllMethodsInSubClass() before the method of a subclass gets executed?

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  • Correct usage of socket_select().

    - by Mark Tomlin
    What is the correct way to use socket_select within PHP to send and receive data? I have a connection to the server that allows for both TCP & UDP packet connections, I am utilizing both. Within these connections I'm both sending and receiving packets on the same port, but the TCP packet will be sent on one port (29999) and UDP will be sent on another port (30000). The transmission type will be that of AF_INET. The IP address will be loopback 127.0.0.1. I have many questions on how to create a socket connection within this scenario. For example, is it better to use socket_create_pair to make the connection, or use just socket_create followed by socket_connect, and then implement socket_select? There is a chance that no data will be sent from the server to the client, and it is up to the client to maintain the connection. This will be done by utilizing the time out function within the socket_select call. Should no data be sent within the time limit, the socket_select function will break and a keep alive packet can then be sent. The following script is of the client. // Create $TCP = socket_create(AF_INET, SOCK_STREAM, SOL_TCP); $UDP = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP); // Misc $isAlive = TRUE; $UDPPort = 30000; define('ISP_ISI', 1); // Connect socket_connect($TCP, '127.0.0.1', 29999); socket_connect($UDP, '127.0.0.1', $UDPPort); // Construct Parameters $recv = array($TCP, $UDP); $null = NULL; // Make The Packet to Send. $packet = pack('CCCxSSxCSa16a16', 44, ISP_ISI, 1, $UDPPort, 0, '!', 0, 'AdminPass', 'SocketSelect'); // Send ISI (InSim Init) Packet socket_write($TCP, $packet); /* Main Program Loop */ while ($isAlive == TRUE) { // Socket Select $sock = socket_select($recv, $null, $null, 5); // Check Status if ($sock === FALSE) $isAlive = FALSE; # Error else if ($sock > 0) # How does one check to find what socket changed? else # Something else happed, don't know what as it's not in the documentation, Could this be our timeout getting tripped? }

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  • Rewriting Live TCP/IP (Layer 4) (i.e. Socket Layer) Streams

    - by user213060
    I have a simple problem which I'm sure someone here has done before... I want to rewrite Layer 4 TCP/IP streams (Not lower layer individual packets or frames.) Ettercap's etterfilter command lets you perform simple live replacements of Layer 4 TCP/IP streams based on fixed strings or regexes. Example ettercap scripting code: if (ip.proto == TCP && tcp.dst == 80) { if (search(DATA.data, "gzip")) { replace("gzip", " "); msg("whited out gzip\n"); } } if (ip.proto == TCP && tcp.dst == 80) { if (search(DATA.data, "deflate")) { replace("deflate", " "); msg("whited out deflate\n"); } } http://ettercap.sourceforge.net/forum/viewtopic.php?t=2833 I would like to rewrite streams based on my own filter program instead of just simple string replacements. Anyone have an idea of how to do this? Is there anything other than Ettercap that can do live replacement like this, maybe as a plugin to a VPN software or something? I would like to have a configuration similar to ettercap's silent bridged sniffing configuration between two Ethernet interfaces. This way I can silently filter traffic coming from either direction with no NATing problems. Note that my filter is an application that acts as a pipe filter, similar to the design of unix command-line filters: >[eth0] <----------> [my filter] <----------> [eth1]< What I am already aware of, but are not suitable: Tun/Tap - Works at the lower packet layer, I need to work with the higher layer streams. Ettercap - I can't find any way to do replacements other than the restricted capabilities in the example above. Hooking into some VPN software? - I just can't figure out which or exactly how. libnetfilter_queue - Works with lower layer packets, not TCP/IP streams. Again, the rewriting should occur at the transport layer (Layer 4) as it does in this example, instead of a lower layer packet-based approach. Exact code will help immensely! Thanks!

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  • Your thoughts on Best Practices for Scientific Computing?

    - by John Smith
    A recent paper by Wilson et al (2014) pointed out 24 Best Practices for scientific programming. It's worth to have a look. I would like to hear opinions about these points from experienced programmers in scientific data analysis. Do you think these advices are helpful and practical? Or are they good only in an ideal world? Wilson G, Aruliah DA, Brown CT, Chue Hong NP, Davis M, Guy RT, Haddock SHD, Huff KD, Mitchell IM, Plumbley MD, Waugh B, White EP, Wilson P (2014) Best Practices for Scientific Computing. PLoS Biol 12:e1001745. http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1001745 Box 1. Summary of Best Practices Write programs for people, not computers. (a) A program should not require its readers to hold more than a handful of facts in memory at once. (b) Make names consistent, distinctive, and meaningful. (c) Make code style and formatting consistent. Let the computer do the work. (a) Make the computer repeat tasks. (b) Save recent commands in a file for re-use. (c) Use a build tool to automate workflows. Make incremental changes. (a) Work in small steps with frequent feedback and course correction. (b) Use a version control system. (c) Put everything that has been created manually in version control. Don’t repeat yourself (or others). (a) Every piece of data must have a single authoritative representation in the system. (b) Modularize code rather than copying and pasting. (c) Re-use code instead of rewriting it. Plan for mistakes. (a) Add assertions to programs to check their operation. (b) Use an off-the-shelf unit testing library. (c) Turn bugs into test cases. (d) Use a symbolic debugger. Optimize software only after it works correctly. (a) Use a profiler to identify bottlenecks. (b) Write code in the highest-level language possible. Document design and purpose, not mechanics. (a) Document interfaces and reasons, not implementations. (b) Refactor code in preference to explaining how it works. (c) Embed the documentation for a piece of software in that software. Collaborate. (a) Use pre-merge code reviews. (b) Use pair programming when bringing someone new up to speed and when tackling particularly tricky problems. (c) Use an issue tracking tool. I'm relatively new to serious programming for scientific data analysis. When I tried to write code for pilot analyses of some of my data last year, I encountered tremendous amount of bugs both in my code and data. Bugs and errors had been around me all the time, but this time it was somewhat overwhelming. I managed to crunch the numbers at last, but I thought I couldn't put up with this mess any longer. Some actions must be taken. Without a sophisticated guide like the article above, I started to adopt "defensive style" of programming since then. A book titled "The Art of Readable Code" helped me a lot. I deployed meticulous input validations or assertions for every function, renamed a lot of variables and functions for better readability, and extracted many subroutines as reusable functions. Recently, I introduced Git and SourceTree for version control. At the moment, because my co-workers are much more reluctant about these issues, the collaboration practices (8a,b,c) have not been introduced. Actually, as the authors admitted, because all of these practices take some amount of time and effort to introduce, it may be generally hard to persuade your reluctant collaborators to comply them. I think I'm asking your opinions because I still suffer from many bugs despite all my effort on many of these practices. Bug fix may be, or should be, faster than before, but I couldn't really measure the improvement. Moreover, much of my time has been invested on defence, meaning that I haven't actually done much data analysis (offence) these days. Where is the point I should stop at in terms of productivity? I've already deployed: 1a,b,c, 2a, 3a,b,c, 4b,c, 5a,d, 6a,b, 7a,7b I'm about to have a go at: 5b,c Not yet: 2b,c, 4a, 7c, 8a,b,c (I could not really see the advantage of using GNU make (2c) for my purpose. Could anyone tell me how it helps my work with MATLAB?)

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  • What Functional features are worth a little OOP confusion for the benefits they bring?

    - by bonomo
    After learning functional programming in Haskell and F#, the OOP paradigm seems ass-backwards with classes, interfaces, objects. Which aspects of FP can I bring to work that my co-workers can understand? Are any FP styles worth talking to my boss about retraining my team so that we can use them? Possible aspects of FP: Immutability Partial Application and Currying First Class Functions (function pointers / Functional Objects / Strategy Pattern) Lazy Evaluation (and Monads) Pure Functions (no side effects) Expressions (vs. Statements - each line of code produces a value instead of, or in addition to causing side effects) Recursion Pattern Matching Is it a free-for-all where we can do whatever the programming language supports to the limit that language supports it? Or is there a better guideline?

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  • Software development magazines [closed]

    - by Sebastian
    Ive spent the last hour or so browsing the web for professional development magazines. I am mostly interested in the java platform, agile methods, "programming in general" (tutorials on languages or whatever, "hot new stuff" etc) and software craftmanship. My best finding yet was pragpub and maybe MSDN magazine. I am willing to pay and have a Zinio account if anyone knows a magazine about programming that is distributed by them. Ive already browsed a couple of related threads here on stackexchange. ACM and IEEE does not seem relevant, as Im not interested in research articles. Maybe conferences like OOPSLA as somebody mentioned in another thread. PS. I prefer if they are in pdf or readable on kindle or a tablet. DS. BR Sebastian

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  • How to connect with MySQL server if it won't connect via the socket?

    - by cwd
    I have an account on a shared server. I have jailshell access and also PhpMyAdmin. I want to run mysql commands via SSH but I'm getting an error: $ mysql -u mySqlUser -p mySqlPw Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' I can connect with PHP and phpMyAdmin, so would it be possible to call mysql from the shell and have it connect via an ip and port instead of the socket? The file /var/lib/mysql/mysql.sock does not exist - maybe that is intentional, and the only thing in /etc/my.cnf is [mysqld] skip-innodb More Info I don't have access to change system settings. I did a search in /var for mysql.sock but found nothing. However, phpMyAdmin might be connecting via a socket somehow: Really it would just be great if I could connect via IP. Also tried these two syntaxes: $ mysql -u mySqlUser -p mySqlPw -h localhost $ mysql -u mySqlUser -p mySqlPw -h localhost -P 3306 Both with the same result: ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

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  • Should a new programmer nowadays start with C/C++ or OOP language? [closed]

    - by deviDave
    I've been a programmer for 15+ years. In my time, we all started with C or C++ and then moved to C# or Java. At that time it was a usual practice. Now, my brother wants to follow my steps and I am not sure what advice to give him. So, I am asking the community for an opinion. Should nowadays new programmer with zero programming knowledge start with functional languages (C, C++, etc.) or he should start directly with OOP languages (Java, C#, etc.)? The reply should be considered in the context of my brother's future assignments. He will mainly work on Java mobile applications as well as ASP.NET web apps. He will have to touch with desktop apps, low level programming, drivers, etc. This is the reason I am not sure if he should ever need to learn functional languages.

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  • I/O error(socket error): [Errno 111] Connection refused

    - by Schitti
    I have a program that uses urllib to periodically fetch a url, and I see intermittent errors like : I/O error(socket error): [Errno 111] Connection refused. It works 90% of the time, but the othe r10% it fails. If retry the fetch immediately after it fails, it succeeds. I'm unable to figure out why this is so. I tried to see if any ports are available, and they are. Any debugging ideas? For additional info, the stack trace is: File "/usr/lib/python2.6/urllib.py", line 235, in retrieve fp = self.open(url, data) File "/usr/lib/python2.6/urllib.py", line 203, in open return getattr(self, name)(url) File "/usr/lib/python2.6/urllib.py", line 342, in open_http h.endheaders() File "/usr/lib/python2.6/httplib.py", line 868, in endheaders self._send_output() File "/usr/lib/python2.6/httplib.py", line 740, in _send_output self.send(msg) File "/usr/lib/python2.6/httplib.py", line 699, in send self.connect() File "/usr/lib/python2.6/httplib.py", line 683, in connect self.timeout) File "/usr/lib/python2.6/socket.py", line 512, in create_connection raise error, msg Edit - A google search isn't very helpful, what I got out of it is that the server I'm fetching from sometimes refuses connections, how can I verify its not a bug in my code and this is indeed the case?

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  • establishing a socket connection from iPhone to MAC/PC

    - by user319572
    Hello, I just started getting into XCode and Co. What I am trying is to send accelerometer data via WLAN to a PC or MAC over a Socket connection. I am trying at the moment with the iPhone simulator, on the other site a netbook with a JAVA program shall receive a test string for starters. Unfortunately my socket will not initialize. What am I doing wrong? NSString *recStr = @"192.168.0.5"; //String with receiver IP NSHost *hoster = [NSHost hostWithName:recStr]; //create a host NSOutputStream *sendData; //create an output stream [NSStream getStreamsToHost:hoster port:8000 inputStream:nil outputStream:&sendData]; [sendData retain]; [sendData setDelegate:self]; [sendData open]; A warning says NSStream may not respond to '+getStreamsToHost:inputSream:outputStream:' So I guess parameters are wrong. But why and how to do it right? The program starts but I don't think I can send anything as long as this warning shows up (have not tried though). Thank you in advance, Andreas

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  • select always returns -1 while trying to read from socket and stdin

    - by Aleyna
    Hello I have the following code implemented on C++(Linux) to check on my listening socket and stdin using select. select however keeps returning -1 no matter what I try to do! What's wrong with that code :s I will appreciate any help. Thanks highsock = m_sock; //listening socket memset((char *) &connectlist, 0, sizeof(connectlist)); memset((char *) &socks, 0, sizeof(socks)); int readsocks; struct timeval timeout; timeout.tv_sec = 60; timeout.tv_usec = 0; while (1) { updateSelectList(); //cout << "highest sock: " << highsock << endl; tempreadset = readset; readsocks = select(highsock+1, &tempreadset, NULL, NULL, &timeout); //cout << "# ready: " << readsocks << endl; if (readsocks < 0) { if (errno == EINTR) continue; cout << "select error" << endl; } if (readsocks > 0) { readFromSocks(); } } void readFromSocks() { if (FD_ISSET(STDIN, &readset)) { ... } else if (FD_ISSET(m_sock, &readset)) { ... } } void updateSelectList() { FD_ZERO(&readset); FD_SET(STDIN, &readset); FD_SET(m_sock, &readset); for (int i=0; i<MAXCONNECTIONS; i++) { if (connectlist[i] != 0) { FD_SET(connectlist[i], &readset); if (connectlist[i] > highsock) highsock = connectlist[i]; } } highsock = max(max(m_sock, STDIN), highsock); }

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  • Scheme vs Haskell for an Introduction to Functional Programming?

    - by haziz
    I am comfortable with programming in C and C#, and will explore C++ in the future. I may be interested in exploring functional programming as a different programming paradigm. I am doing this for fun, my job does not involve computer programming, and am somewhat inspired by the use of functional programming, taught fairly early, in computer science courses in college. Lambda calculus is certainly beyond my mathematical abilities, but I think I can handle functional programming. Which of Haskell or Scheme would serve as a good intro to functional programming? I use emacs as my text editor and would like to be able to configure it more easily in the future which would entail learning Emacs Lisp. My understanding, however, is that Emacs Lisp is fairly different from Scheme and is also more procedural as opposed to functional. I would likely be using "The Little Schemer" book, which I have already bought, if I pursue Scheme (seems to me a little weird from my limited leafing through it). Or would use the "Learn You a Haskell for Great Good" if I pursue Haskell. I would also watch the Intro to Haskell videos by Dr Erik Meijer on Channel 9. Any suggestions, feedback or input appreciated. Thanks. P.S. BTW I also have access to F# since I have Visual Studio 2010 which I use for C# development, but I don't think that should be my main criteria for selecting a language.

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