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  • Android Service setForeground While Display Sleeps

    - by c12
    I have a background Android Service that's purpose is to communicate with another device (non-phone) using a Bluetooth socket. Everything works fine except that the service gets stopped and restarted by the OS when the phone display is sleeping. This restart sometimes leaves a 15-20 minute gaps where there is no communication between the Service and the Bluetooth device and I need to be able to query the device every minute. Is startForeground the proper approach? Attempted to use: startForeground(int, Notification) //still see gaps when phone sleeps Service: public class ForegroundBluetoothService extends Service{ private boolean isStarted = false; @Override public void onDestroy() { super.onDestroy(); stop(); } /** * @see android.app.Service#onBind(android.content.Intent) */ @Override public IBinder onBind(Intent intent) { return null; } /** * @see android.app.Service#onStartCommand(android.content.Intent, int, int) */ @Override public int onStartCommand(Intent intent, int flags, int startId) { loadServiceInForeground(); return(START_STICKY); } private void loadServiceInForeground() { if (!isStarted) { isStarted=true; Notification notification = new Notification(R.drawable.icon, "Service is Running...", System.currentTimeMillis()); Intent notificationIntent = new Intent(this, MainScreen.class); PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0); notification.setLatestEventInfo(this, "Notification Title", "Service is Running...", pendingIntent); startForeground(12345, notification); try{ queryTheBluetoothDevice(); } catch(Exception ex){ ex.printStackTrace(); } } } private void stop() { if (isStarted) { isStarted=false; stopForeground(true); } } }

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  • How to limit TCP writes to particular size and then block untlil the data is read

    - by ustulation
    {Qt 4.7.0 , VS 2010} I have a Server written in Qt and a 3rd party client executable. Qt based server uses QTcpServer and QTcpSocket facilities (non-blocking). Going through the articles on TCP I understand the following: the original implementation of TCP mentioned the negotiable window size to be a 16-bit value, thus maximum being 65535 bytes. But implementations often used the RFC window-scale-extension that allows the sliding window size to be scalable by bit-shifting to yield a maximum of 1 gigabyte. This is implementation defined. This could have resulted in majorly different window sizes on receiver and sender end as the server uses Qt facilities without hardcoding any window size limit. Client 1st asks for all information it can based on the previous messages from the server before handling the new (accumulating) incoming messages. So at some point Server receives a lot of messages each asking for data of several MB's. This the server processes and puts it into the sender buffer. Client however is unable to handle the messages at the same pace and it seems that client’s receiver buffer is far smaller (65535 bytes maybe) than sender’s transmit window size. The messages thus get accumulated at sender’s end until the sender’s buffer is full too after which the TCP writes on sender would block. This however does not happen as sender buffer is much larger. Hence this manifests as increase in memory consumption on the sender’s end. To prevent this from happening, I used Qt’s socket’s waitForBytesWritten() with timeout set to -1 for infinite waiting period. This as I see from the behaviour blocks the thread writing TCP data until the data has actually been sensed by the receiver’s window (which will happen when earlier messages have been processed by the client at application level). This has caused memory consumption at Server end to be almost negligible. is there a better alternative to this (in Qt) if i want to restrict the memory consumption at server end to say x MB's? Also please point out if any of my understandings is incorrect.

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  • Segmentation Fault

    - by Biranchi
    Hi All, I have the following piece of code for getting the hostname and IP address, #include <stdlib.h> #include <stdio.h> #include <netdb.h> /* This is the header file needed for gethostbyname() */ #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> int main(int argc, char *argv[]) { struct hostent *he; if (argc!=2){ printf("Usage: %s <hostname>\n",argv[0]); exit(-1); } if ((he=gethostbyname(argv[1]))==NULL){ printf("gethostbyname() error\n"); exit(-1); } printf("Hostname : %s\n",he->h_name); /* prints the hostname */ printf("IP Address: %s\n",inet_ntoa(*((struct in_addr *)he->h_addr))); /* prints IP address */ } but i am getting a warning and segmentation fault as host.c: In function ‘main’: host.c:24: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘int’ What is the error in the code ?? Thanks

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  • Large Switch statements: Bad OOP?

    - by Mystere Man
    I've always been of the opinion that large switch statements are a symptom of bad OOP design. In the past, I've read articles that discuss this topic and they have provided altnerative OOP based approaches, typically based on polymorphism to instantiate the right object to handle the case. I'm now in a situation that has a monsterous switch statement based on a stream of data from a TCP socket in which the protocol consists of basically newline terminated command, followed by lines of data, followed by an end marker. The command can be one of 100 different commands, so I'd like to find a way to reduce this monster switch statement to something more manageable. I've done some googling to find the solutions I recall, but sadly, Google has become a wasteland of irrelevant results for many kinds of queries these days. Are there any patterns for this sort of problem? Any suggestions on possible implementations? One thought I had was to use a dictionary lookup, matching the command text to the object type to instantiate. This has the nice advantage of merely creating a new object and inserting a new command/type in the table for any new commands. However, this also has the problem of type explosion. I now need 100 new classes, plus I have to find a way to interface them cleanly to the data model. Is the "one true switch statement" really the way to go? I'd appreciate your thoughts, opinions, or comments.

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  • Client Server communication in Java - which approach to use?

    - by markovuksanovic
    I have a typical client server communication - Client sends data to the server, server processes that, and returns data to the client. The problem is that the process operation can take quite some time - order of magnitude - minutes. There are a few approaches that could be used to solve this. Establish a connection, and keep it alive, until the operation is finished and the client receives the response. Establish connection, send data, close the connection. Now the processing takes place and once it is finished the server could establish a connection to the client to send the data. Establish a connection, send data, close the connection. Processing takes place. client asks server, every n minutes/seconds if the operation is finished. If the processing is finished the client fetches the data. I was wondering which approach would be the best way to use. Is there maybe some "de facto" standard for solving this problem? How "expensive" is opening a socket in Java? Solution 1. seems pretty nasty to me, but 2. and 3. could do. The problem with solution 2. is that the server needs to know on which port the client is listening, while solution 3. adds some network overhead.

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  • What is the best way of doing this? (WCF 4)

    - by Jason Porter
    I have a multith-threaded, continusly running application that connects with multiple devices via TCP/IP sockets and exposes a set of WCF API's for controlling, monitoring and reporting on these devices. I would like to host this on IIS for the ususal reasons of not having to worry about re-starting the app in case of errors. So the issue I have is the main application running in parallel with the WCF Servies. To accomplish this I use the static AppInitialize class to start a thread which has the main applicaiton loop. The WCF services mostly report or control the shared objects with this thread. There are two problems that I see with this approach. One is that if the thread dies, IIS has no clue to re-start it so I have to play some tricks with some WCF calls. The other is that the backrgound thread deals with potentially thousands of devices that are connected permanently (typically a thread per socket connection). So I am not sure if IIS is buying me anything in this case. Another approach that I am thinking is to use WF for the main application that deals with the sockets and host both the WF and my WCF services in IIS using AppFabric. Since I have not use WF or AppFabric I am reaching out to see if this would be good approach or there are better alternative.

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  • Why does my Perl TCP server script hang with many TCP connections?

    - by viraptor
    I've got a strange issue with a server accepting TCP connections. Even though there are normally some processes waiting, at some volume of connections it hangs. Long version: The server is written in Perl and binds a $srv socket with the reuse flag and listen == 5. Afterwards, it forks into 10 processes with a loop of $clt=$srv->accept(); do_processing($clt); $clt->shutdown(2); The client written in C is also very simple - it sends some lines, then receives all lines available and does a shutdown(sockfd, 2); There's nothing async going on and at the end both send and receive queues are empty (as reported by netstat). Connections last only ~20ms. All clients behave the same way, are the same implementation, etc. Now let's say I'm accepting X connections from client 1 and another X from client 2. Processes still report that they're idle all the time. If I add another X connections from client 3, suddenly the server processes start hanging just after accepting. The first blocking thing they do after accept(); is while (<$clt>) ... - but they don't get any data (on the first try already). Suddenly all 10 processes are in this state and do not stop waiting. On strace, the server processes seem to hang on read(), which makes sense. There are loads of connections in TIME_WAIT state belonging to that server (~100 when the problem starts to manifest), but this might be a red herring. What could be happening here?

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  • Low Throughput on Windows Named Pipe Over WAN

    - by MichaelB76
    I'm having problems with low performance using a Windows named pipe. The throughput drops off rapidly as the network latency increases. There is a roughly linear relationship between messages sent per second and round trip time. It seems that the client must ack each message before the server will send the next one. This leads to very poor performance, I can only send 5 (~100 byte) messages per second over a link with an RTT of 200 ms. The pipe is asynchronous, using multiple overlapped write operations (and multiple overlapped reads at the client end), but this is not improving throughput. Is it possible to send messages in parallel over a named pipe? The pipe is created using PIPE_TYPE_MESSAGE, would PIPE_READMODE_BYTE work better? Is there any other way I can improve performance? This is a deployed solution, so I can't simply replace the pipe with a socket connection (I've read that Windows named pipe aren't recommended for use over a WAN, and I'm wondering if this is why). I'd be grateful for any help with this matter.

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  • Issue changing innodb_log_file_size

    - by savageguy
    I haven't done much tweaking in the past so this might be relatively easy however I am running into issues. This is what I do: Stop MySQL Edit my.cnf (changing innodb_log_file_size) Remove ib_logfile0/1 Start MySQL Starts fine however all InnoDB tables have the .frm file is invalid error, the status shows InnoDB engine is disabled so I obviously go back, remove the change and everything works again. I was able to change every other variable I've tried but I can't seem to find out why InnoDB fails to start even after removing the log files. Am I missing something? Thanks. Edit: Pasting of the log below - looks like it still seems to find the log file even though they are not there? Shutdown: 090813 10:00:14 InnoDB: Starting shutdown... 090813 10:00:17 InnoDB: Shutdown completed; log sequence number 0 739268981 090813 10:00:17 [Note] /usr/sbin/mysqld: Shutdown complete Startup after making the changes: InnoDB: Error: log file ./ib_logfile0 is of different size 0 5242880 bytes InnoDB: than specified in the .cnf file 0 268435456 bytes! 090813 11:00:18 [Warning] 'user' entry '[email protected]' ignored in --skip-name-resolve mode. 090813 11:00:18 [Note] /usr/sbin/mysqld: ready for connections. Version: '5.0.81-community-log' socket: '/var/lib/mysql/mysql.sock' port: 3306 MySQL Community Edition (GPL) 090813 11:00:19 [ERROR] /usr/sbin/mysqld: Incorrect information in file: './XXXX/User.frm' 090813 11:00:19 [ERROR] /usr/sbin/mysqld: Incorrect information in file: './XXXX/User.frm' 090813 11:00:19 [ERROR] /usr/sbin/mysqld: Incorrect information in file: './XXXX/User.frm' Its just a spam of the same error until I correct it When it did start after it recreated the log files so it must be looking in the same spot I am.

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  • What do I do about a Java program that spawned two instaces of itself?

    - by user288915
    I have a java JAR file that is triggered by a SQL server job. It's been running successfully for months. The process pulls in a structured flat file to a staging database then pushes that data into an XML file. However yesterday the process was triggered twice at the same time. I can tell from a log file that gets created, it looks like the process ran twice simultaneously. This caused a lot of issues and the XML file that it kicked out was malformed and contained duplicate nodes etc. My question is, is this a known issue with Java JVM's spawning multiple instances of itself? Or should I be looking at sql server as the culprit? I'm looking into 'socket locking' or file locking to prevent multiple instances in the future. This is the first instance of this issue that I've ever heard of. More info: The job is scheduled to run every minute. The job triggers a .bat file that contains the java.exe - jar filename.jar The java program runs, scans a directory for a file and then executes a loop to process if the file if it finds one. After it processes the file it runs another loop that kicks out XML messages. I can provide code samples if that would help. Thank you, Kevin

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  • coredate data not show at tableView

    - by pengwang
    hello,i used coredate at the tableView,when i enter the viewControl i will call: dispatch_queue_t downloadQueue = dispatch_queue_create("socket login", NULL); dispatch_async(downloadQueue, ^{ NSManagedObjectContext *managedObjectContext =[self getManagedObjectContext]; noticListArr=[[CoreDataManager sharedInstance] readEvent:@"NotificationEntity" SortDescriptor:nil managedObjectContext:managedObjectContext]; NSLog(@"refreshData.count:%d ",noticListArr.count); for(int i=0;i<noticListArr.count;i++){ NotificationEntity *notificationEntity=[noticListArr objectAtIndex:i]; NSLog(@"notificationEntity.name:%@ ",notificationEntity.name); NSLog(@"notificationEntity.describeString:%@ ",notificationEntity.describeString); NSLog(@"notificationEntity.source:%@", notificationEntity.source); } }); dispatch_async(dispatch_get_main_queue(), ^{ [self.tableView1 reloadData]; }); dispatch_release(downloadQueue); all log have value but when i used - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"NotificationViewCell"; NotificationViewCell *cell = (NotificationViewCell*)[tableView dequeueReusableCellWithIdentifier:CellIdentifier]; NotificationEntity *notificationEntity=(NotificationEntity *)[noticListArr objectAtIndex:indexPath.row]; NSLog(@"tableViewnoticListArr.count:%d ",noticListArr.count); NSLog(@"indexPath.row:%d ",indexPath.row); NSLog(@"notificationTable.avatarsmall:%@", notificationEntity.avatarsmall); NSLog(@"notificationTable.source:%@", notificationEntity.source); NSLog(@"notificationTable.name:%@", notificationEntity.name); NSLog(@"notificationTable.describeString:%@ ",notificationEntity.describeString); } only NSLog(@"tableViewnoticListArr.count:%d ",noticListArr.count); NSLog(@"indexPath.row:%d ",indexPath.row); can give me correct result.but all notificationEntity.name notificationEntity.describeString is null.i donot know why at the tabelview cell all value of notificationEntity is null.

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  • Choosing approach for an IM client-server app

    - by John
    Update: totally re-wrote this to be more succint. I'm looking at a new application, one part of which will be very similar to standard IM clients, i.e text chat, ability to send attachments, maybe some real-time interaction like a multi-user whiteboard. It will be client-server, i.e all traffic goes through my central server. That means if I want to support cross-communication with other IM systems, I am still free to pick any protocol for my own client<--server communication - my server can use XMPP or whatever to talk to other systems. Clients are expected to include desktop apps, but probably also browser-based as well either through Flex/Silverlight or HTML/AJAX. I see 3 options for my own client-server communication layer: XMPP. The benefits are clients already exist as do open-source servers. However it requires the most up-front research/learning and also appears like it might raise legal issues due to GPL. Custom sockets. A server app makes connections with the clients, allowing any text/binary data to be sent very fast. However this approach requires building said server from scratch, and also makes a JS client tricky Servlets (or similar web server). Using tried and tested Java web-stack, clients send HTTP requests similar to AJAX-based websites. The benefit is the server is easy to write using well-established technologies, and easy to talk to. But what restrictions would this bring? Is it appropriate technology for real-time communication? Advice and suggests are welcome, especially what pros and cons surround using a web-server approach as compared to a socket-based approach.

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  • Is a web-server (e.g servlets) a good solution for an IM server?

    - by John
    I'm looking at a new app, broadly speaking an IM application with a strong client-server model - all communications go through a server so they can be logged centrally. The server will be Java in some form, clients could at this point be anything from a .NET Desktop app to Flex/Silverlight, to a simple web-interface using JS/AJAX. I had anticipated doing the server using standard J2EE so I get a thread-safe, multi-user server for 'free'... to make things simple let's say using Servlets (but in practice SpringMVC would be likely). This all seemed very neat but I'm concerned if the stateless nature of Servlets is the best approach. If my memory of servlets (been a year or two) is right, each time a client sent a HTTP request, typically a new message entered by the user, the servlet could not assume it had the user/chat in memory and might have to get it from the DB... regardless it has to look it up. Then it either has to use some PUSH system to inform other members of the chat, or cache that there are new messages, for other clients who poll the server using AJAX or similar - and when they poll it again has to lookup the chat, including new messages, and send the new data. I'm wondering if a better system would be the server is running core Java, and implements a socket-based communication with clients. This allows much more immediate data transfer and is more flexible if say the IM client included some game you could play. But then you're writing a custom server and sockets don't sound very friendly to a browser-based client on current browsers. Am I missing some big piece of the puzzle here, it kind of feels like I am? Perhaps a better way to ask the question would simply be "if the client was browser-based using HTML/JS and had to run on IE7+,FF2+ (i.e no HTML5), how would you implement the server?" edit: if you are going to suggest using XMPP, I have been trying to get my head around this in another question, so please consider if that's a more appropriate place to discuss this specifically.

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  • Using Threads to Handle Sockets

    - by user340468
    I am working on a java program that is essentially a chat room. This is an assignment for class so no code please, I am just having some issues determining the most feasible way to handle what I need to do. I have a server program already setup for a single client using threads to get the data input stream and a thread to handle sending on the data output stream. What I need to do now is create a new thread for each incoming request. My thought is to create a linked list to contain either the client sockets, or possibly the thread. Where I am stumbling is figuring out how to handle sending the messages out to all the clients. If I have a thread for each incoming message how can I then turn around and send that out to each client socket. I'm thinking that if I had a linkedlist of the clientsockets I could then traverse the list and send it out to each one, but then I would have to create a dataoutputstream each time. Could I create a linkedlist of dataoutputstreams? Sorry if it sounds like I'm rambling but I don't want to just start coding this, it could get messy without a good plan. Thanks!

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  • Sockets and COBOL

    - by kati
    I have received a job at a hospital which still uses COBOL for all organizational work, the whole (now 20 Terabyte) database (Which was a homebrew in, guess what, COBOL) is filled with the data of every patient since the last 45 (or so) years. So that was my story. Now to my question: Currently, all sockets were (from what I've seen) implemented by COBOL programs writing their data into files. These files then were read out by C++ programs (That was an additional module added in the late 1980s) and using C++ sockets sent to the database. Now this solution has stopped working as they are moving the database from COBOL to COBOL, yes - they didn't use MySQL or so - they implemented a new database - again in COBOL. I asked the guy that worked there before me (hes around 70 now) why the hell someone would do that and he told me that he is so good at COBOL that he doesn't want to write it in any other language. So far so good now my question: How can I implement socket connections in COBOL? I need to create an interface to the external COBOL database located at, for example, 192.168.1.23:283.

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  • Receiving UDP on different Android phones gives different results

    - by user1868982
    I am willing to create a server and client program on my android mobile devices. The devices communicate with each other on the same wifi network, therefore, some simple scanning mechanism must be implemented - The client phones search for a server phone through some kind of broadcast. What I did: My protocol - the client phone broadcasts a message port p on the wifi, the server listens on port p. when the server gets the broadcast message it sends a message back, therefore discovering itself to the client. My code - I have opened a broadcast socket on my app, it sends a broadcast message. Meanwhile there is a python script on my PC that listens and replies - I use python so that my testing will be easier - Wireshark on the PC and I can see everything. What happens: When I use one of my Galaxy S phones - it works and I get a response. When I use the other Galaxy S phone - it doesn't work. Now this is what I know: The phone that works actually has Nexus ROM on it Ver. 4.1.1 The phone that doesn't work has 2.3.3 regular galaxy ROM The python code says it receives both of the broadcasts sent from both phones, and replies to both of them without raising any exception. So far I was thought the problem may be 1. the older version'd phone. 2. the windows firewall 3. the router firewall So I have opened Wireshark, and Indeed I saw that both phones are sending their broadcasts - it was logged on Wireshark. But the python script only responded to the first one. So this is why 1 & 3 are irrelevant - if the router firewall was blocking my UDP I would have still seen the python server response, same with the older versioned phone. To get rid of 2 i just disabled the windows firewall - still same problem. Does anyone has a clue to why this effect might happen? Thanks!

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  • localhost yes but phpmyadmin blank

    - by Giskin Leow
    WAMP people having problem with both localhost and phpmyadmin loads blank which usually the port problem. Mine is only phpmyadmin blank. sqlbuddy and phpinfo no problem. tried uninstall reinstalled wamp. tried xampp, same problem, all works well, not phpmyadmin. mysql log: 120905 8:03:08 [Note] Plugin 'FEDERATED' is disabled. 120905 8:03:08 InnoDB: The InnoDB memory heap is disabled 120905 8:03:08 InnoDB: Mutexes and rw_locks use Windows interlocked functions 120905 8:03:08 InnoDB: Compressed tables use zlib 1.2.3 120905 8:03:09 InnoDB: Initializing buffer pool, size = 128.0M 120905 8:03:09 InnoDB: Completed initialization of buffer pool 120905 8:03:09 InnoDB: highest supported file format is Barracuda. 120905 8:03:09 InnoDB: Waiting for the background threads to start 120905 8:03:10 InnoDB: 1.1.8 started; log sequence number 1595675 120905 8:03:11 [Note] Server hostname (bind-address): '(null)'; port: 3306 120905 8:03:11 [Note] - '(null)' resolves to '::'; 120905 8:03:11 [Note] - '(null)' resolves to '0.0.0.0'; 120905 8:03:11 [Note] Server socket created on IP: '0.0.0.0'. 120905 8:03:13 [Note] Event Scheduler: Loaded 0 events 120905 8:03:13 [Note] wampmysqld: ready for connections. apache log [Wed Sep 05 08:03:09 2012] [notice] Apache/2.2.22 (Win32) PHP/5.4.3 configured -- resuming normal operations [Wed Sep 05 08:03:09 2012] [notice] Server built: May 13 2012 13:32:42 [Wed Sep 05 08:03:09 2012] [notice] Parent: Created child process 3812 [Wed Sep 05 08:03:09 2012] [notice] Child 3812: Child process is running [Wed Sep 05 08:03:09 2012] [notice] Child 3812: Acquired the start mutex. [Wed Sep 05 08:03:09 2012] [notice] Child 3812: Starting 64 worker threads. [Wed Sep 05 08:03:09 2012] [notice] Child 3812: Starting thread to listen on port 80. [Wed Sep 05 08:03:09 2012] [notice] Child 3812: Starting thread to listen on port 80. [Wed Sep 05 08:04:14 2012] [error] [client 127.0.0.1] File does not exist: C:/wamp/www/favicon.ico [Wed Sep 05 08:09:50 2012] [error] [client 127.0.0.1] File does not exist: C:/wamp/www/favicon.ico [Wed Sep 05 08:41:03 2012] [error] [client 127.0.0.1] File does not exist: C:/wamp/www/phpMyAdmin

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  • Unable to run JAR file (created in Eclipse)

    - by Trist
    I hate starting a post with this but I'm new to Java... I've followed this tutorial to create a socket server (mines in Eclipse). I can run the server within Eclipse, all is well. But when I try to export the project I can't figure out how to run it. I keep getting this error (it varies depending on how I run it) Exception in thread "main" java.lang.NoClassDefFoundError: xsocketserver/Main Caused by: java.lang.ClassNotFoundException: xsocketserver.Main at java.net.URLClassLoader$1.run(URLClassLoader.java:200) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:188) at java.lang.ClassLoader.loadClass(ClassLoader.java:315) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:330) at java.lang.ClassLoader.loadClass(ClassLoader.java:250) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:398) I've read this problem relates to class paths being set. I've tried the following: java -cp libs/xSocket-2.8.12.jar xsocketserver.Main java -jar xSocketServer.jar java -classpath xSocketServer:xSocketServer/libs/xSocket-2.8.12.jar xsocketserver.Main plus many others. The file structure within the JAR is as follows: xSocketServer.jar -> xsocketserver -> Main.class -> xSocketDataHandler.class -> META-INF -> MANIFEST.MF -> libs -> xSocket-2.8.12.jar Incidentally I've tried adding my own manifest file which contains the Class-Path but when I check it it always reads: Manifest-Version: 1.0 Main-Class: xsocketserver.Main I'm guessing this is a common problem based on the number of hits I've seen in Google but I can't fathom what I'm doing wrong. Wrong Export settings maybe??

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  • Sending Images over Sockets in C

    - by Takkun
    I'm trying to send an image file through a TCP socket in C, but the image isn't being reassembled correctly on the server side. I was wondering if anyone can point out the mistake? I know that the server is receiving the correct file size and it constructs a file of that size, but it isn't an image file. Client //Get Picture Size printf("Getting Picture Size\n"); FILE *picture; picture = fopen(argv[1], "r"); int size; fseek(picture, 0, SEEK_END); size = ftell(picture); //Send Picture Size printf("Sending Picture Size\n"); write(sock, &size, sizeof(size)); //Send Picture as Byte Array printf("Sending Picture as Byte Array\n"); char send_buffer[size]; while(!feof(picture)) { fread(send_buffer, 1, sizeof(send_buffer), picture); write(sock, send_buffer, sizeof(send_buffer)); bzero(send_buffer, sizeof(send_buffer)); } Server //Read Picture Size printf("Reading Picture Size\n"); int size; read(new_sock, &size, sizeof(1)); //Read Picture Byte Array printf("Reading Picture Byte Array\n"); char p_array[size]; read(new_sock, p_array, size); //Convert it Back into Picture printf("Converting Byte Array to Picture\n"); FILE *image; image = fopen("c1.png", "w"); fwrite(p_array, 1, sizeof(p_array), image); fclose(image);

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  • PHP get values from SimpleXMLElement array

    - by seanp2k
    I have this: [1]=> object(SimpleXMLElement)#6 (1) { ["@attributes"]=> array(14) { ["name"]=> string(5) "MySQL" ["acknowledged"]=> string(1) "1" ["comments"]=> string(1) "1" ["current_check_attempt"]=> string(1) "1" ["downtime"]=> string(1) "0" ["last_check"]=> string(19) "2010-05-01 17:57:00" ["markdown_filter"]=> string(1) "0" ["max_check_attempts"]=> string(1) "3" ["output"]=> string(42) "CRITICAL - Socket timeout after 10 seconds" ["perfdata_available"]=> string(1) "1" ["service_object_id"]=> string(3) "580" ["state"]=> string(8) "critical" ["state_duration"]=> string(6) "759439" ["unhandled"]=> string(1) "0" } } (I used var_dump($child) to generate that) How do I get the 'name' attribute out of there as a string? Here is my code: $xml = simplexml_load_string($results); foreach($xml->data->list as $child) { var_dump($child); echo $child->getName() . ": " . $child->name . "<br />"; }

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  • How can I get size in bytes of an object sent using RMI?

    - by Lucas Batistussi
    I'm implementing a cache server with MongoDB and ConcurrentHashMap java class. When there are available space to put object in memory, it will put at. Otherwise, the object will be saved in a mongodb database. Is allowed that user specify a size limit in memory (this should not exceed heap size limit obviously!) for the memory cache. The clients can use the cache service connecting through RMI. I need to know the size of each object to verify if a new incoming object can be put into memory. I searched over internet and i got this solution to get size: public long getObjectSize(Object o){ try { ByteArrayOutputStream bos = new ByteArrayOutputStream(); ObjectOutputStream oos = new ObjectOutputStream(bos); oos.writeObject(o); oos.close(); return bos.size(); } catch (Exception e) { return Long.MAX_VALUE; } } This solution works very well. But, in terms of memory use doesn't solve my problem. :( If many clients are verifying the object size at same time this will cause stack overflow, right? Well... some people can say: Why you don't get the specific object size and store it in memory and when another object is need to put in memory check the object size? This is not possible because the objects are variable in size. :( Someone can help me? I was thinking in get socket from RMI communication, but I don't know how to do this...

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  • new project app; use entirely node.js

    - by Jared
    I have been looking into Node.js, express and Nowjs and love how easy it is to have real time interactions between clients. My background is mostly from CodeIgniter MVC using PHP and MYSql. I want to re make a current web project of mine from scratch to make everything better and more real time with this newer technology. After researching and doing test examples I want to use node.js , express and Nowjs for the real time interactions once someone connects to the socket.io to pull data back to clients. But use Code Igniter for the control of the site and user management , possible shopping cart/store , pretty much everything else. This is purely due to time constraints and that I am already familiar with doing it that way. I have been looking at MongoDB as an alternative to MySql, Basically the app is going to be multiple chat rooms all on one page. with the ability of notifications and private messaging. Lots of data transfer and images. before I started piecing it together I wanted to get people who have already done something similar. My model would use Code Igniter and MySQL to render the page and then connect them onto a node.js server and broadcast using express and nowjs would using a mongoDB be better than mySQL for tons of messages and data being stored or MYSQL? Also does it make since to not make the whole site on Node.js , kinda piece it together like that?

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  • How should a multi-threaded C application handle a failed malloc()?

    - by user294463
    A part of an application I'm working on is a simple pthread-based server that communicates over a TCP/IP socket. I am writing it in C because it's going to be running in a memory constrained environment. My question is: what should the program do if one of the threads encounters a malloc() that returns NULL? Possibilities I've come up with so far: No special handling. Let malloc() return NULL and let it be dereferenced so that the whole thing segfaults. Exit immediately on a failed malloc(), by calling abort() or exit(-1). Assume that the environment will clean everything up. Jump out of the main event loop and attempt to pthread_join() all the threads, then shut down. The first option is obviously the easiest, but seems very wrong. The second one also seems wrong since I don't know exactly what will happen. The third option seems tempting except for two issues: first, all of the threads need not be joined back to the main thread under normal circumstances and second, in order to complete the thread execution, most of the remaining threads will have to call malloc() again anyway. What shall I do?

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  • c# How to get string from byte?

    - by Kade
    I have a form-console application which does a TCP socket connections for send and receive. I need help getting the following response to STRING. The following code does write the RESPONSE to the console, but i also want to byte[] b = new byte[100]; int k = s.Receive(b); Console.WriteLine("Recieved..."); for (int i = 0; i < k; i++) Console.Write(Convert.ToChar(b[i])); ASCIIEncoding asen = new ASCIIEncoding(); s.Send(asen.GetBytes("RECEIVED :")); i want to get something like String GETSTRING; byte[] b = new byte[100]; int k = s.Receive(b); Console.WriteLine("Recieved..."); for (int i = 0; i < k; i++) Console.Write(Convert.ToChar(b[i])); GETSTRING = *WHATEVER RESPONSE RECEIVED ABOVE* ASCIIEncoding asen = new ASCIIEncoding(); s.Send(asen.GetBytes("RECEIVED :"));

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  • java Sockets and Threads Problem

    - by vs4vijay
    I am doin a Some Socket Programing Stuff in Java.. Here i have created a button(Create Server)..and when i click it ,it starts server...but i want to change the button name to (Stop Server) after Starting the server... so i did this.. but when i press start server it starts and the button name remains the same... and when a client gets connected to it ,then it change the name to stop server... tell me whats the wrong with this code?? Here is My a SomePart Of Code... public void actionPerformed(ActionEvent ex) { if(ex.getActionCommand() == "CreateServer") { bt1.setText("Stop Server"); bt2.setEnabled(false); b5.setText("Server Started On Port " + tf2.getText()); System.out.println("Server started 1"); create(Integer.parseInt(tf2.getText())); //my func. to create server System.out.println("Server started 2"); } } and my create() fucn. contains some sockets and thread...so tell me what the problem...

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