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  • How do you get the ethernet address using Java?

    - by Frank Krueger
    I would like to retrieve the ethernet address of the network interface that is used to access a particular website. How can this be done in Java? Solution Note that the accepted solution of getHardwareAddress is only available in Java 6. There does not seem to be a solution for Java 5 aside from executing i(f|p)confing.

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  • Accessing mapped network drive from ColdFusion

    - by Kip
    I am having a problem accessing a mapped drive in ColdFusion. I have \\server\files\sharing mapped to z:\. If I run this code, it says the directory exists for the full path but not for the mapped one: <cfscript> fullPath = "\\server\files\sharing\reports"; mappedPath = "z:\reports"; WriteOutput("fullPath exists: #DirectoryExists(fullPath)#<br/>"); //YES WriteOutput("mappedPath exists: #DirectoryExists(mappedPath)#"); //NO </cfscript> I have done some Googling and have found a few people with the same problem, but the solution was always to use the full path. Is there a reason ColdFusion wouldn't be able to see or access the mapped drive? And if so, are there any workarounds (maybe a system call to get the full path of the mapped drive)?

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  • Which programming language to use for serious project?

    - by alex
    Hi! Which programming language to use for serious web project (price catalogue)? After some time of studying web PHP frameworks i got that: Codeigniter: good, but when i read about authorization (that 20% users can login correctly without party solutions), i am disappointed. Zend Framework: more serious, but raises questions about speed and i found only few examples. PHP: long time to understand PHP frameworks functionality

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  • Can Bonjour browse a service with a particular name?

    - by Roman
    Bonjour provides "DNSSD.browse(serviceType,callBackObject)" method which browses for services of a particular type. If a service of the given type is found, Bonjour call "callBackObject.serviceFound". If the service is lost, Bonjour calls "callBackObject.serviceLost". I alway considered "DNSSD.browse" as a method for monitoring a particular service. Bonjour monitors a particular service and calls necessary method if the service is found (available) or lost (not available). But than I realized that "DNSSD.browse" receives (as argument) a type of service (for example "http.tcp") and there can be several services of this type. So, its probably calls "serviceFound" and "serviceLost" if any service of the specified type is found or lost, respectively. But in my application I would like to browse just for one particular service. What is the best way to do it? I have two potential solutions: When I register a service, I give it a unique type. For example: "server1.http.tcp". I register services with unique names (not types) and ask Bonjour to browse for services with particular names. But I am not sure that Bonjour provide such possibility. Can it browse for services with specific names?

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  • How frequently IP packets are fragmented at the source host?

    - by Methos
    I know that if IP payload MTU then routers usually fragment the IP packet. Finally all the fragmented packets are assembled at the destination using the fields IP-ID, IP fragment offsets and fragmentation flags. Max length of IP payload is 64K. Thus its very plausible for L4 to hand over payload which is 64K. If the L2 protocol is Ethernet, which often is the case, then the MTU will be about 1600 bytes. Hence IP packet will be fragmented at the source host itself. However, a quick search about IP implementation in Linux tells me that in recent kernels, L4 protocols are fragment friendly i.e. they try to save the fragmentation work for IP by handing over buffers of size which is close to MTU. Considering these two facts, I am wondering about how frequently does the IP packet gets fragmented at the source host itself. Does it occur sometimes/rarely/never? Does anyone know if there are exceptions to the rule of fragmentation in linux kernel (i.e. are there situations where L4 protocols are not fragment friendly)? How is this handled in other common OSes like windows? In general how frequently IP packets are fragmented?

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  • how to send an array of bytes over a TCP connection (java programming)

    - by Mark Roberts
    Can somebody demonstrate how to send an array of bytes over a TCP connection from a sender program to a receiver program in Java. (I'm new to Java programming, and can't seem to find an example of how to do this that shows both ends of the connection (sender and receiver.) If you know of an existing example, maybe you could post the link. (No need to reinvent the wheel.) P.S. This is NOT homework! :-)

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  • Android, NetworkInfo.getTypeName(), NullpointerException

    - by moppel
    I have an activity which shows some List entries. When I click on a list item my app checks which connection type is available ("WIF" or "MOBILE"), through NetworkInfo.getTypeName(). As soon as I call this method I get a NullpointerException. Why? I tested this on the emulator, cause my phone is currently not available (it's broken...). I assume this is the problem? This is the only explanation that I have, if that's not the case I have no idea why this would be null. Here's some code snippet: public class VideoList extends ListActivity{ ... public void onCreate(Bundle bundle){ final ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE); ... listview.setOnItemClickListener(new OnItemClickListener(){ public void onItemClick(AdapterView<?> parent, View view, int position, long id) { ... NetworkInfo ni = cm.getActiveNetworkInfo(); String connex = ni.getTypeName(); //Nullpointer exception here if(connex.equals("WIFI")doSomething(); } }); } }

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  • C programming doubt!!!

    - by aks
    Hi, I am having a programming doubt? Please have a look at the below mentioned code snippet and tell me the difference? int main() { struct sockaddr_in serv_addr, cli_addr; /* Initialize socket structure */ bzero((char *) &serv_addr, sizeof(serv_addr)); } Now, what if i do something similar without typecasting (char *), then also i feel it will do the same thing? Can someone clarify? /* Initialize socket structure */ bzero( &serv_addr, sizeof(serv_addr));

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  • API to Rank blog articles

    - by mnml
    I would like to know if there is any easy way to rank blog articles by counting how many times they have been retweeted / digg'ed / buzz'ed and if there is an existing api for it. The idea would be to keep important 'stories' at the top of the blog timeline.

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  • An existing connection was forcibly closed by the remote host

    - by peter
    I am working with a commercial application which is throwing a SocketException with the message, An existing connection was forcibly closed by the remote host This happens with a socket connection between client and server. The connection is alive and well, and heaps of data is being transferred, but it then becomes disconnected out of nowhere. Has anybody seen this before? What could the causes be? I can kind of guess a few causes, but also is there any way to add more into this code to work out what the cause could be? Any comments / ideas are welcome. Thanks.

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  • Programatically determining maximum transfer rate

    - by dauphic
    I have a problem that requires me to calculate the maximum upload and download available, then limit my program's usage to a percentage of it. However, I can't think of a good way to find the maximums. At the moment, the only solution I can come up with is transfering a few megabytes between the client and server, then measuring how ling the transfer took. This solution is very undesirable, however, because with 100,000 clients it could potentially result in too much of an increase to our server's bandwidth usage (which is already too high). Does anyone have any solutions to this problem?

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  • Is Stream.Write thread-safe?

    - by Mike Spross
    I'm working on a client/server library for a legacy RPC implementation and was running into issues where the client would sometimes hang when waiting to a receive a response message to an RPC request message. It turns out the real problem was in my message framing code (I wasn't handling message boundaries correctly when reading data off the underlying NetworkStream), but it also made me suspicious of the code I was using to send data across the network, specifically in the case where the RPC server sends a large amount of data to a client as the result of a client RPC request. My send code uses a BinaryWriter to write a complete "message" to the underlying NetworkStream. The RPC protocol also implements a heartbeat algorithm, where the RPC server sends out PING messages every 15 seconds. The pings are sent out by a separate thread, so, at least in theory, a ping can be sent while the server is in the middle of streaming a large response back to a client. Suppose I have a Send method as follows, where stream is a NetworkStream: public void Send(Message message) { //Write the message to a temporary stream so we can send it all-at-once MemoryStream tempStream = new MemoryStream(); message.WriteToStream(tempStream); //Write the serialized message to the stream. //The BinaryWriter is a little redundant in this //simplified example, but here because //the production code uses it. byte[] data = tempStream.ToArray(); BinaryWriter bw = new BinaryWriter(stream); bw.Write(data, 0, data.Length); bw.Flush(); } So the question I have is, is the call to bw.Write (and by implication the call to the underlying Stream's Write method) atomic? That is, if a lengthy Write is still in progress on the sending thread, and the heartbeat thread kicks in and sends a PING message, will that thread block until the original Write call finishes, or do I have to add explicit synchronization to the Send method to prevent the two Send calls from clobbering the stream?

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  • Event feed implementation - will it scale?

    - by SlappyTheFish
    Situation: I am currently designing a feed system for a social website whereby each user has a feed of their friends' activities. I have two possible methods how to generate the feeds and I would like to ask which is best in terms of ability to scale. Events from all users are collected in one central database table, event_log. Users are paired as friends in the table friends. The RDBMS we are using is MySQL. Standard method: When a user requests their feed page, the system generates the feed by inner joining event_log with friends. The result is then cached and set to timeout after 5 minutes. Scaling is achieved by varying this timeout. Hypothesised method: A task runs in the background and for each new, unprocessed item in event_log, it creates entries in the database table user_feed pairing that event with all of the users who are friends with the user who initiated the event. One table row pairs one event with one user. The problems with the standard method are well known – what if a lot of people's caches expire at the same time? The solution also does not scale well – the brief is for feeds to update as close to real-time as possible The hypothesised solution in my eyes seems much better; all processing is done offline so no user waits for a page to generate and there are no joins so database tables can be sharded across physical machines. However, if a user has 100,000 friends and creates 20 events in one session, then that results in inserting 2,000,000 rows into the database. Question: The question boils down to two points: Is this worst-case scenario mentioned above problematic, i.e. does table size have an impact on MySQL performance and are there any issues with this mass inserting of data for each event? Is there anything else I have missed?

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  • Syncronizing mobile phone contacts with contacts from social networks

    - by Pentium10
    I retrieve a JSON list of contacts from a social network site. It contains firstname, lastname, displayname, data1, data2, etc... What is the efficient way to quickly lookup my local phone contacts database and "match" them based on their name. Since there are firstname, lastname and displayname this can vary. What do you think, how can the best match be achieved? Also how do I make sure I don't parse for each JSON item the whole database I want to avoide having JSON_COUNT x MOBILE COUNT steps.

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  • VB6 Serial port programming

    - by commodus86
    I'm not much experienced in VB6 serial port programming. I need to control another circuit through serial port. (I have heard that pin 4 and pin 7 are used for that purpose. If these pins are incorrect please tell me what pins are used for such purposes) My requirement is to set those pins to high or low and read their levels(high or low) through VB6 program. How to do the task?? Thanx,

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  • Why sockets does not die when server dies? Why socket dies when server is alive?

    - by Roman
    I try to play with sockets a bit. For that I wrote very simple "client" and "server" applications. Client: import java.net.*; public class client { public static void main(String[] args) throws Exception { InetAddress localhost = InetAddress.getLocalHost(); System.out.println("before"); Socket clientSideSocket = null; try { clientSideSocket = new Socket(localhost,12345,localhost,54321); } catch (ConnectException e) { System.out.println("Connection Refused"); } System.out.println("after"); if (clientSideSocket != null) { clientSideSocket.close(); } } } Server: import java.net.*; public class server { public static void main(String[] args) throws Exception { ServerSocket listener = new ServerSocket(12345); while (true) { Socket serverSideSocket = listener.accept(); System.out.println("A client-request is accepted."); } } } And I found a behavior that I cannot explain: I start a server, than I start a client. Connection is successfully established (client stops running and server is running). Then I close the server and start it again in a second. After that I start a client and it writes "Connection Refused". It seems to me that the server "remember" the old connection and does not want to open the second connection twice. But I do not understand how it is possible. Because I killed the previous server and started a new one! I do not start the server immediately after the previous one was killed (I wait like 20 seconds). In this case the server "forget" the socket from the previous server and accepts the request from the client. I start the server and then I start the client. Connection is established (server writes: "A client-request is accepted"). Then I wait a minute and start the client again. And server (which was running the whole time) accept the request again! Why? The server should not accept the request from the same client-IP and client-port but it does!

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  • Checking online users with Facebook Javascript SDK

    - by Roman
    Hi, I'm trying to build some kind of a social game in facebook, where I need that every user that has approved my APP is able to receive notifications from me. When the user approves my App, I save his UID in the DB for future reference. At some later time, I want to make it possible for other users find partners for a game - so I need a way to pick randomly some user from my DB and check if he's online. Then, send him a message and propose to play with the current player. So 2 questions: How can I check if some user is online, using Javascript SDK? It seems that in the new Graph API I can't get the users' online status. How can I then send him a message and propose to play the game? When he approves to play - he is being forwarded to the game page. Many thanks in advance, Roman

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  • Windows Mobile: "My network card connects to" registry settings

    - by Martin Robins
    Can anybody please tell me the registry setting(s) that are affected in Windows Mobile 6.1 when a user selects Start - Settings - Connections - Wi-Fi and then changes the value of the "My network card connects to" drop down list on the "Network Adapters" tab? I have a device that seems to default this to "The Internet" when in fact the Wi-Fi connects to the corporate network and I would like to be able to change this programatically rather than expecting 250+ users to have to do it manually every time they reboot their devices. Thanks.

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  • UDP sockets in ad hoc network (Ubuntu 9.10)

    - by Ekhiotz
    Hi! I am using BSD sockets in Ubuntu 9.10 to send UDP packets in broadcast with the following code: sock_fd = socket(PF_INET,SOCK_DGRAM,IPPROTO_UDP); //sock_fd=socket(AF_INET,SOCK_DGRAM,0); receiver_addr.sin_family = PF_INET; //does not send with broadcast in ad hoc receiver_addr.sin_addr.s_addr = htonl(INADDR_BROADCAST); inet_aton("169.254.255.255",&receiver_addr.sin_addr); receiver_addr.sin_port = htons(port); int broadcast = 1; // this call is what allows broadcast packets to be sent: if (setsockopt(sock_fd, SOL_SOCKET, SO_BROADCAST, &broadcast, sizeof broadcast) == -1) { perror("setsockopt (SO_BROADCAST)"); exit(1); } ret=sendto(sock_fd, packet, size, 0,(struct sockaddr*)&receiver_addr,sizeof(receiver_addr)); Note that is not all the code, it is only to have an idea. The program sends all the data with INADDR_BROADCAST if I am connected to an infrastructure wireless network. However, if my laptop is connected to an ad-hoc network, it is able to receive all the data, but not to send it. I have solved the problem using the 169.254.255.255 broadcast address, but I would like to know what is going on. Thank you in advance!

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  • Socket.recv works but not gets or read?

    - by Earlz
    Hello I've been messing around with Sockets in Ruby some and came across some example code that I tried modifying and broke. I want to know why it's broken. Server: require "socket" dts = TCPServer.new('127.0.0.1', 20000) loop do Thread.start(dts.accept) do |s| print(s, " is accepted\n") s.write(Time.now) print(s, " is gone\n") s.close end end Client that works: require 'socket' streamSock = TCPSocket.new( "127.0.0.1", 20000 ) streamSock.print( "Hello\n" ) str = streamSock.recv( 100 ) print str streamSock.close Client that is broken require 'socket' streamSock = TCPSocket.new( "127.0.0.1", 20000 ) streamSock.print( "Hello\n" ) str=streamSock.read #this line modified print str streamSock.close I know that the streamSock.print is unnecessary (as well as the naming scheme being non-ruby) but I don't understand why read doesn't work while recv does, Why is this?

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  • Socket.Recieve Failing When Multithreaded

    - by Qua
    The following piece of code runs fine when parallelized to 4-5 threads, but starts to fail as the number of threads increase somewhere beyond 10 concurrentthreads int totalRecieved = 0; int recieved; StringBuilder contentSB = new StringBuilder(4000); while ((recieved = socket.Receive(buffer, SocketFlags.None)) > 0) { contentSB.Append(Encoding.ASCII.GetString(buffer, 0, recieved)); totalRecieved += recieved; } The Recieve method returns with zero bytes read, and if I continue calling the recieve method then I eventually get a 'An established connection was aborted by the software in your host machine'-exception. So I'm assuming that the host actually sent data and then closed the connection, but for some reason I never recieved it. I'm curious as to why this problem arises when there are a lot of threads. I'm thinking it must have something to do with the fact that each thread doesn't get as much execution time and therefore there are some idle time for the threads which causes this error. Just can't figure out why idle time would cause the socket not to recieve any data.

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