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• Circumvent c++ null-terminated string frustration

  - by ypnos

  I'm using boost::program_options and it suffers from the same as many other c++ libs, even std itself: It still uses C-style null-terminated strings, because nobody really likes the weak std::string. The method in question is: options_description_easy_init& operator()(const char* name, const value_semantic* s, const char* description); The typical use case is just fine: options.add_options() ("graphical", bool_switch(&isGraphical)->default_value(false), "Show any graphical output during runtime") However, I need the name of the option to be set dynamically. The reason is that in some cases I nead a custom prefix, which is added to the string by my function std::string key(const std::string& k): options.add_options() (key("graphical"), bool_switch(&isGraphical)->default_value(false), "Show any graphical output during runtime") This fails. I could now use c_str() on the std::string but that's evil -- I don't know how long program_options keeps the variable around and if my string is still alive when needed. I could also reserve memory in a buffer etc. and hand in that. The buffer is never freed and it sucks/is evil. Is there anything else I can do to circumvent the C-style string mess in this situation?

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• Is there a general-purpose printf-ish routine defined in any C standard

  - by supercat

  In many C libraries, there is a printf-style routine which is something like the following: int __vgprintf(void *info, (void)(*print_function(void*, char)), const char *format, va_list params); which will format the supplied string and call print_function with the passed-in info value and each character in sequence. A function like fprintf will pass __vgprintf the passed-in file parameter and a pointer to a function which will cast its void* to a FILE* and output the passed-in character to that file. A function like snprintf will create a struct holding a char* and length, and pass the address of that struct to a function which will output each character in sequence, space permitting. Is there any standard for such a function, which could be used if e.g. one wanted a function to output an arbitrary format to a TCP port? A common approach is to allocate a buffer one hopes is big enough, use snprintf to put the data there, and then output the data from the buffer. It would seem cleaner, though, if there were a standard way to to specify that the print formatter should call a user-supplied routine with each character.

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• sendto is returning ENOBUF

  - by user338159

  Hi, I am currently running an old system on Tru64 which involves lots of UDP sockets using the sendto() function. The sockets are used in our code to send messages to/from various processes and then eventually on to a thick client app that is connected remotely. Occasionally the socket to the thick client gets stuck, this can cause some of these messages to get built up. My question is how can I determine the current buffer size, and how do I determine the maximum message buffer. The code below gives a snippet of how I set up the port and use the sendto function. /* need to adjust the maximum size we can send on this / / as it needs to be able to cope with the biggest / / messages we send / lenlen = sizeof(len) ; / allow double for when the system is under load */ len = 2 * C_MAX_MESSAGE_DATA_SIZE ; lpos_setsockopt(FATAL, msg_socket,SOL_SOCKET, SO_SNDBUF, &len, lenlen, &error_no) ; result = sendto( msg_socket, (char *)message, (int)message_len, flags, dest_addr, addrlen); Note. We have ported this application to Linux and the problem does not seem to appear there. Any help would be greatly appreciated. Regards

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• Response as mail attachment

  - by el ninho

  using (MemoryStream stream = new MemoryStream()) { compositeLink.PrintingSystem.ExportToPdf(stream); Response.Clear(); Response.Buffer = false; Response.AppendHeader("Content-Type", "application/pdf"); Response.AppendHeader("Content-Transfer-Encoding", "binary"); Response.AppendHeader("Content-Disposition", "attachment; filename=test.pdf"); Response.BinaryWrite(stream.GetBuffer()); Response.End(); } I got this working fine. Next step is to send this pdf file to mail, as attachment using (MemoryStream stream = new MemoryStream()) { compositeLink.PrintingSystem.ExportToPdf(stream); Response.Clear(); Response.Buffer = false; Response.AppendHeader("Content-Type", "application/pdf"); Response.AppendHeader("Content-Transfer-Encoding", "binary"); Response.AppendHeader("Content-Disposition", "attachment; filename=test.pdf"); Response.BinaryWrite(stream.GetBuffer()); System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage(); message.To.Add("[email protected]"); message.Subject = "Subject"; message.From = new System.Net.Mail.MailAddress("[email protected]"); message.Body = "Body"; message.Attachments.Add(Response.BinaryWrite(stream.GetBuffer())); System.Net.Mail.SmtpClient smtp = new System.Net.Mail.SmtpClient("192.168.100.100"); smtp.Send(message); Response.End(); } I have problem with this line: message.Attachments.Add(Response.BinaryWrite(stream.GetBuffer())); Any help how to get this to work? Thanks

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• C++, Ifstream opens local file but not file on HTTP Server

  - by fammi

  Hi, I am using ifstream to open a file and then read from it. My program works fine when i give location of the local file on my system. for eg /root/Desktop/abc.xxx works fine But once the location is on the http server the file fails to open. for eg http://192.168.0.10/abc.xxx fails to open. Is there any alternate for ifstream when using a URL address? thanks. part of the code where having problem: bool readTillEof = (endIndex == -1) ? true : false; // Open the file in binary mode and seek to the end to determine file size ifstream file ( fileName.c_str ( ), ios::in|ios::ate|ios::binary ); if ( file.is_open ( ) ) { long size = (long) file.tellg ( ); long numBytesRead; if ( readTillEof ) { numBytesRead = size - startIndex; } else { numBytesRead = endIndex - startIndex + 1; } // Allocate a new buffer ptr to read in the file data BufferSptr buf (new Buffer ( numBytesRead ) ); mpStreamingClientEngine->SetResponseBuffer ( nextRequest, buf ); // Seek to the start index of the byte range // and read the data file.seekg ( startIndex, ios::beg ); file.read ( (char *)buf->GetData(), numBytesRead ); // Pass on the data to the SCE // and signal completion of request mpStreamingClientEngine->HandleDataReceived( nextRequest, numBytesRead); mpStreamingClientEngine->MarkRequestCompleted( nextRequest ); // Close the file file.close ( ); } else { // Report error to the Streaming Client Engine // as unable to open file AHS_ERROR ( ConnectionManager, " Error while opening file \"%s\"\n", fileName.c_str ( ) ); mpStreamingClientEngine->HandleRequestFailed( nextRequest, CONNECTION_FAILED ); } }

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• Is there a way to receive data as unsigned char over UDP on Qt?

  - by user269037

  I need to send floating point numbers using a UDP connection to a Qt application. Now in Qt the only function available is qint64 readDatagram ( char * data, qint64 maxSize, QHostAddress * address = 0, quint16 * port = 0 ) which accepts data in the form of signed character buffer. I can convert my float into a string and send it but it will obviously not be very efficient converting a 4 byte float into a much longer sized character buffer. I got hold of these 2 functions to convert a 4 byte float into an unsinged 32 bit integer to transfer over network which works fine for a simple C++ UDP program but for Qt I need to receive the data as unsigned char. Is it possible to avoid converting the floatinf point data into a string and then sending it? uint32_t htonf(float f) { uint32_t p; uint32_t sign; if (f < 0) { sign = 1; f = -f; } else { sign = 0; } p = ((((uint32_t)f)&0x7fff)<<16) | (sign<<31); // Whole part and sign. p |= (uint32_t)(((f - (int)f) * 65536.0f))&0xffff; // Fraction. return p; } float ntohf(uint32_t p) { float f = ((p>>16)&0x7fff); // Whole part. f += (p&0xffff) / 65536.0f; // Fraction. if (((p>>31)&0x1) == 0x1) { f = -f; } // Sign bit set. return f; }

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• What would happen if a same file being read and appended at the same time(python programming)?

  - by Shane

  I'm writing a script using two separate thread one doing file reading operation and the other doing appending, both threads run fairly frequently. My question is, if one thread happens to read the file while the other is just in the middle of appending strings such as "This is a test" into this file, what would happen? I know if you are appending a smaller-than-buffer string, no matter how frequently you read the file in other threads, there would never be incomplete line such as "This i" appearing in your read file, I mean the os would either do: append "This is a test" - read info from the file; or: read info from the file - append "This is a test" to the file; and such would never happen: append "This i" - read info from the file - append "s a test". But if "This is a test" is big enough(assuming it's a bigger-than-buffer string), the os can't do appending job in one operation, so the appending job would be divided into two: first append "This i" to the file, then append "s a test", so in this kind of situation if I happen to read the file in the middle of the whole appending operation, would I get such result: append "This i" - read info from the file - append "s a test", which means I might read a file that includes an incomplete string?

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• no default constructor exists for class

  - by MixedCoder

  #include "Includes.h" enum BlowfishAlgorithm { ECB, CBC, CFB64, OFB64, }; class Blowfish { public: struct bf_key_st { unsigned long P[18]; unsigned long S[1024]; }; Blowfish(BlowfishAlgorithm algorithm); void Dispose(); void SetKey(unsigned char data[]); unsigned char Encrypt(unsigned char buffer[]); unsigned char Decrypt(unsigned char buffer[]); char EncryptIV(); char DecryptIV(); private: BlowfishAlgorithm _algorithm; unsigned char _encryptIv[200]; unsigned char _decryptIv[200]; int _encryptNum; int _decryptNum; }; class GameCryptography { public: Blowfish _blowfish; GameCryptography(unsigned char key[]); void Decrypt(unsigned char packet[]); void Encrypt(unsigned char packet[]); Blowfish Blowfish; void SetKey(unsigned char k[]); void SetIvs(unsigned char i1[],unsigned char i2[]); }; GameCryptography::GameCryptography(unsigned char key[]) { } Error:IntelliSense: no default constructor exists for class "Blowfish" ???!

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• Is it possible to anti alias using Copy swap effect?

  - by Nor

  I'm developing an application in VB.Net using Managed DirectX that runs in windowed mode and renders onto a picture box that is smaller than the form. Whenever I resize the form, the back buffer is streched to fit the picture box. This is not what I would like. The backbuffer size is the same as screen size, however, I only want to render a part of the back buffer, whose size is controlled by the size of the picture box into which I'm rendering. Resetting the device with new presentation parameters is something I would like to avoid. I'm aware that I can use an overload of Device.Present if I set the swap effect to copy, but this doesn't allow me to use Multi Sample Anti Alias (which requires the Discard swap effect). It seems to me that the overload Device.Present is not usable with any other swap effect than copy, and throws an exception. An other alternative I considered is the PresentFlags.DeviceClip, however it seems that it works only for Windows XP. I'm using Windows 7 and it doesn't seem to be doing anything. So, is it even possible that I use anti-aliasing in this situation?

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• Need help implementing this algorithm with map reduce(hadoop)

  - by Julia

  Hi all! i have algorithm that will go through a large data set read some text files and search for specific terms in those lines. I have it implemented in Java, but I didnt want to post code so that it doesnt look i am searching for someone to implement it for me, but it is true i really need a lot of help!!! This was not planned for my project, but data set turned out to be huge, so teacher told me I have to do it like this. I was reading about MapReduce and thaught that i first do the standard implementation and then it will be more/less easier to do it with mapreduce. But didnt happen, since algorithm is quite stupid and nothing special, and map reduce...i cant wrap my mind around it. So here is shortly pseudo code of my algorithm LIST termList (there is method that creates this list from lucene index) FOLDER topFolder INPUT topFolder IF it is folder and not empty list files (there are 30 sub folders inside) FOR EACH sub folder GET file "CheckedFile.txt" analyze(CheckedFile) ENDFOR END IF Method ANALYZE(CheckedFile) read CheckedFile WHILE CheckedFile has next line GET line FOR(loops through termList) GET third word from line IF third word = term from list append whole line to string buffer ENDIF ENDFOR END WHILE OUTPUT string buffer to file Also, as you can see, each time when "analyze" is called, new file has to be created, i understood that map reduce is difficult to write to many outputs??? I understand mapreduce intuition, and my example seems perfectly suited for mapreduce, but when it comes to do this, obviously I do not know enough and i am STUCK! Please please help.

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• Multithreading: Read from / write to a pipe

  - by Tero Jokinen

  I write some data to a pipe - possibly lots of data and at random intervals. How to read the data from the pipe? Is this ok: in the main thread (current process) create two more threads (2, 3) the second thread writes sometimes to the pipe (and flush-es the pipe?) the 3rd thread has infinite loop which reads the pipe (and then sleeps for some time) Is this so far correct? Now, there are a few thing I don't understand: do I have to lock (mutex?) the pipe on write? IIRC, when writing to pipe and its buffer gets full, the write end will block until I read the already written data, right? How to check for read data in the pipe, not too often, not too rarely? So that the second thread wont block? Is there something like select for pipes? It is possible to set the pipe to unbuffered more or I have to flush it regularly - which one is better? Should I create one more thread, just for flushing the pipe after write? Because flush blocks as well, when the buffer is full, right? I just don't want the 1st and 2nd thread to block.... [Edit] Sorry, I thought the question is platform agnostic but just in case: I'm looking at this from Win32 perspective, possibly MinGW C...

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• why no implicit conversion from pointer to reference to const pointer.

  - by user316606

  I'll illustrate my question with code: #include <iostream> void PrintInt(const unsigned char*& ptr) { int data = 0; ::memcpy(&data, ptr, sizeof(data)); // advance the pointer reference. ptr += sizeof(data); std::cout << std::hex << data << " " << std::endl; } int main(int, char**) { unsigned char buffer[] = { 0x11, 0x11, 0x11, 0x11, 0x22, 0x22, 0x22, 0x22, }; /* const */ unsigned char* ptr = buffer; PrintInt(ptr); // error C2664: ... PrintInt(ptr); // error C2664: ... return 0; } When I run this code (in VS2008) I get this: error C2664: 'PrintInt' : cannot convert parameter 1 from 'unsigned char *' to 'const unsigned char *&'. If I uncomment the "const" comment it works fine. However shouldn't pointer implicitly convert into const pointer and then reference be taken? Am I wrong in expecting this to work? Thanks!

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• Overlay an image over video using OpenGL ES shaders

  - by BlueVoodoo

  I am trying to understand the basic concepts of OpenGL. A week into it, I am still far from there. Once I am in glsl, I know what to do but I find getting there is the tricky bit. I am currently able to pass in video pixels which I manipulate and present. I have then been trying to add still image as an overlay. This is where I get lost. My end goal is to end up in the same fragment shader with pixel data from both my video and my still image. I imagine this means I need two textures and pass on two pixel buffers. I am currently passing the video pixels like this: glGenTextures(1, &textures[0]); //target, texture glBindTexture(GL_TEXTURE_2D, textures[0]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_BGRA, GL_UNSIGNED_BYTE, buffer); Would I then repeat this process on textures[1] with the second buffer from the image? If so, do I then bind both GL_TEXTURE0 and GL_TEXTURE1? ...and would my shader look something like this? uniform sampler2D videoData; uniform sampler2D imageData; once I am in the shader? It seems no matter what combination I try, image and video always ends up being just video data in both these. Sorry for the many questions merged in here, just want to clear my many assumptions and move on. To clarify the question a bit, what do I need to do to add pixels from a still image in the process described? ("easy to understand" sample code or any types of hints would be appreciated).

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• Testing for a closed socket

  - by Robert S. Barnes

  I'm trying to test for a closed socket that has been gracefully closed by the peer without incurring the latency hit of a double send to induce a SIGPIPE. One of the assumptions here is that the socket if closed was gracefully closed by the peer immediately after it's last write / send. Actual errors like a premature close are dealt with else where in the code. If the socket is still open, there will be 0 or more bytes data which I don't actually want to pull out of the socket buffer yet. I was thinking that I could call int ret = recv(sockfd, buf, 1, MSG_DONTWAIT | MSG_PEEK); to determine if the socket is still connected. If it's connected but there's no data in the buffer I'll get a return of -1 with errno == EAGAIN and return the sockfd for reuse. If it's been gracefully closed by the peer I'll get ret == 0 and open a new connection. I've tested this and it seems to work. However, I suspect there is a small window between when I recv the last bit of my data and when the peer FIN arrives in which I could get a false-positive EAGAIN from my test recv. Is this going to bite me, or is there a better way of doing this?

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• POSIX Sockets: How to detect Ctrl-C sent over Telnet?

  - by ogott

  Short Question What's the right way to handle a Ctrl-C event sent over Telnet on the server side? Long Question After calling recv() on a socket, I'd like to handle some situations appropriately. One of them is to return a certain error code when Ctrl-C was received. What's the correct way to detect this? The following works, but it just doesn't seem right: size_t recv_count; static char ctrl_c[5] = {0xff, 0xf4, 0xff, 0xfd, 0x06}; recv_count = recv(socket, buffer, buffer_size, 0); if (recv_count == sizeof(ctrl_c) && memcmp(buffer, ctrl_c, sizeof(ctrl_c) == 0) { return CTRL_C_RECEIVED; } I found a comment on Ctrl-C in a side-note in this UNIX Socket FAQ: [...] (by the way, out-of-band is often used for that ctrl-C, too). As I understand, receiving out-of-band data is done using recv() with a certain flag as the last parameter. But when I'm waiting for data using recv() as I do in the code above, I can't read out-of-band data at the same time. Apart from that, I'm getting something using recv() without that oob-flag.

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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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• How to check if a thread is busy in C#?

  - by Sam

  I have a Windows Forms UI running on a thread, Thread1. I have another thread, Thread2, that gets tons of data via external events that needs to update the Windows UI. (It actually updates multiple UI threads.) I have a third thread, Thread3, that I use as a buffer thread between Thread1 and Thread2 so that Thread2 can continue to update other threads (via the same method). My buffer thread, Thread3, looks like this: public class ThreadBuffer { public ThreadBuffer(frmUI form, CustomArgs e) { form.Invoke((MethodInvoker)delegate { form.UpdateUI(e); }); } } What I would like to do is for my ThreadBuffer to check whether my form is currently busy doing previous updates. If it is, I'd like for it to wait until it frees up and then invoke the UpdateUI(e). I was thinking about either: a) //PseudoCode while(form==busy) { // Do nothing; } form.Invoke((MethodInvoker)delegate { form.UpdateUI(e); }); How would I check the form==busy? Also, I am not sure that this is a good approach. b) Create an event in form1 that will notify the ThreadBuffer that it is ready to process. // psuedocode List<CustomArgs> elist = new List<CustomArgs>(); public ThreadBuffer(frmUI form, CustomArgs e) { from.OnFreedUp += from_OnFreedUp(); elist.Add(e); } private form_OnFreedUp() { if (elist.count == 0) return; form.Invoke((MethodInvoker)delegate { form.UpdateUI(elist[0]); }); elist.Remove(elist[0]); } In this case, how would I write an event that will notify that the form is free? and c) an other ideas?

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• Python server open all ports

  - by user1670178

  I am trying to open all ports using this code, why can I not create a loop to perform this function? http://www.kellbot.com/2010/02/tutorial-writing-a-tcp-server-in-python/ #!/usr/bin/python # This is server.py file ##server.py from socket import * #import the socket library n=1025 while n<1050: ##let's set up some constants HOST = '' #we are the host PORT = n #arbitrary port not currently in use ADDR = (HOST,PORT) #we need a tuple for the address BUFSIZE = 4096 #reasonably sized buffer for data ## now we create a new socket object (serv) ## see the python docs for more information on the socket types/flags serv = socket( AF_INET,SOCK_STREAM) ##bind our socket to the address serv.bind((ADDR)) #the double parens are to create a tuple with one element serv.listen(5) #5 is the maximum number of queued connections we'll allow serv = socket( AF_INET,SOCK_STREAM) ##bind our socket to the address serv.bind((ADDR)) #the double parens are to create a tuple with one element serv.listen(5) #5 is the maximum number of queued connections we'll allow print 'listening...' n=n+1 conn,addr = serv.accept() #accept the connection print '...connected!' conn.send('TEST') conn.close() How do I make this work so that I can specify input range and have the server open all ports up to 65535? #!/usr/bin/python # This is server.py file from socket import * #import the socket library startingPort=input("\nPlease enter starting port: ") startingPort=int(startingPort) #print startingPort def connection(): ## let's set up some constants HOST = '' #we are the host PORT = startingPort #arbitrary port not currently in use ADDR = (HOST,PORT) #we need a tuple for the address BUFSIZE = 4096 #reasonably sized buffer for data def socketObject(): ## now we create a new socket object (serv) serv = socket( AF_INET,SOCK_STREAM) def bind(): ## bind our socket to the address serv = socket( AF_INET,SOCK_STREAM) serv.bind((ADDR)) #the double parens are to create a tuple with one element serv.listen(5) #5 is the maximum number of queued connections we'll allow serv = socket( AF_INET,SOCK_STREAM) print 'listening...' def accept(): conn,addr = serv.accept() #accept the connection print '...connected!' conn.send('TEST') def close(): conn.close() ## Main while startingPort<65535: connection() socketObject() bind() accept() startingPort=startingPort+1

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• Serving files (800MB) results in an empty file

  - by azz0r

  Hello, with the following code, small files are served fine, however large (see, 800MB and above) result in empty files! Would I need to do something with apache to solve this? <?php class Model_Download { function __construct($path, $file_name) { $this->full_path = $path.$file_name; } public function execute() { if ($fd = fopen ($this->full_path, "r")) { $fsize = filesize($this->full_path); $path_parts = pathinfo($this->full_path); $ext = strtolower($path_parts["extension"]); switch ($ext) { case "pdf": header("Content-type: application/pdf"); // add here more headers for diff. extensions header("Content-Disposition: attachment; filename=\"".$path_parts["basename"]."\""); // use 'attachment' to force a download break; default; header("Content-type: application/octet-stream"); header("Content-Disposition: filename=\"".$path_parts["basename"]."\""); break; } header("Content-length: $fsize"); header("Cache-control: private"); //use this to open files directly while(!feof($fd)) { $buffer = fread($fd, 2048); echo $buffer; } } fclose ($fd); exit; } }

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• file transfer through bluetooth

  - by venkat

  is it possible to transfer files from one android phone to any other device through bluetooth? if possible the send give me a link the sample code... switch (msg.what) { case MESSAGE_STATE_CHANGE: if(D) Log.i(TAG, "MESSAGE_STATE_CHANGE: " + msg.arg1); switch (msg.arg1) { case BluetoothChatService.STATE_CONNECTED: mTitle.setText(R.string.title_connected_to); mTitle.append(mConnectedDeviceName); mConversationArrayAdapter.clear(); break; case BluetoothChatService.STATE_CONNECTING: mTitle.setText(R.string.title_connecting); break; case BluetoothChatService.STATE_LISTEN: case BluetoothChatService.STATE_NONE: mTitle.setText(R.string.title_not_connected); break; } break; case MESSAGE_WRITE: byte[] writeBuf = (byte[]) msg.obj; // construct a string from the buffer String writeMessage = new String(writeBuf); mConversationArrayAdapter.add("Me: " + writeMessage); break; case MESSAGE_READ: byte[] readBuf = (byte[]) msg.obj; // construct a string from the valid bytes in the buffer String readMessage = new String(readBuf, 0, msg.arg1); mConversationArrayAdapter.add(mConnectedDeviceName+": " + readMessage); break; case MESSAGE_DEVICE_NAME: // save the connected device's name mConnectedDeviceName = msg.getData().getString(DEVICE_NAME); Toast.makeText(getApplicationContext(), "Connected to " + mConnectedDeviceName, Toast.LENGTH_SHORT).show(); break; case MESSAGE_TOAST: Toast.makeText(getApplicationContext(), msg.getData().getString(TOAST), Toast.LENGTH_SHORT).show(); break;

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• linux find the command invoked

  - by Subbu

  I am writing a C program which determines the number of bytes read from the standard input . I found out there are ways to give input to the program piped input redirection entering into command line while the program is waiting for input How to find the exact command by which the program was executed from the shell . I tried using command-line arguments but failed . #include <stdio.h> int main(int argc,char *argv[]) { char buffer[100]; int n; for(n=1;n<argc;n++) printf("argument: %s\t",argv[n]); printf("\n"); if(argc==1) printf("waiting for input :"); else if (argc==3) printf("Not waiting for input . Got the source from command itself ."); n = read(0,buffer,100); if(n==-1) printf("\nError occured in reading"); printf("\nReading successfully done\n"); return 0; } Also ,

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• WPF unity Activation error occured while trying to get instance of type

  - by Traci

  I am getting the following error when trying to Initialise the Module using Unity and Prism. The DLL is found by return new DirectoryModuleCatalog() { ModulePath = @".\Modules" }; The dll is found and the Name is Found #region Constructors public AdminModule( IUnityContainer container, IScreenFactoryRegistry screenFactoryRegistry, IEventAggregator eventAggregator, IBusyService busyService ) : base(container, screenFactoryRegistry) { this.EventAggregator = eventAggregator; this.BusyService = busyService; } #endregion #region Properties protected IEventAggregator EventAggregator { get; set; } protected IBusyService BusyService { get; set; } #endregion public override void Initialize() { base.Initialize(); } #region Register Screen Factories protected override void RegisterScreenFactories() { this.ScreenFactoryRegistry.Register(ScreenKeyType.ApplicationAdmin, typeof(AdminScreenFactory)); } #endregion #region Register Views and Various Services protected override void RegisterViewsAndServices() { //View Models this.Container.RegisterType<IAdminViewModel, AdminViewModel>(); } #endregion the code that produces the error is: namespace Microsoft.Practices.Composite.Modularity protected virtual IModule CreateModule(string typeName) { Type moduleType = Type.GetType(typeName); if (moduleType == null) { throw new ModuleInitializeException(string.Format(CultureInfo.CurrentCulture, Properties.Resources.FailedToGetType, typeName)); } return (IModule)this.serviceLocator.GetInstance(moduleType); <-- Error Here } Can Anyone Help Me Error Log Below: General Information Additional Info: ExceptionManager.MachineName: xxxxx ExceptionManager.TimeStamp: 22/02/2010 10:16:55 AM ExceptionManager.FullName: Microsoft.ApplicationBlocks.ExceptionManagement, Version=1.0.3591.32238, Culture=neutral, PublicKeyToken=null ExceptionManager.AppDomainName: Infinity.vshost.exe ExceptionManager.ThreadIdentity: ExceptionManager.WindowsIdentity: xxxxx 1) Exception Information Exception Type: Microsoft.Practices.Composite.Modularity.ModuleInitializeException ModuleName: AdminModule Message: An exception occurred while initializing module 'AdminModule'. - The exception message was: Activation error occured while trying to get instance of type AdminModule, key "" Check the InnerException property of the exception for more information. If the exception occurred while creating an object in a DI container, you can exception.GetRootException() to help locate the root cause of the problem. Data: System.Collections.ListDictionaryInternal TargetSite: Void HandleModuleInitializationError(Microsoft.Practices.Composite.Modularity.ModuleInfo, System.String, System.Exception) HelpLink: NULL Source: Microsoft.Practices.Composite StackTrace Information at Microsoft.Practices.Composite.Modularity.ModuleInitializer.HandleModuleInitializationError(ModuleInfo moduleInfo, String assemblyName, Exception exception) at Microsoft.Practices.Composite.Modularity.ModuleInitializer.Initialize(ModuleInfo moduleInfo) at Microsoft.Practices.Composite.Modularity.ModuleManager.InitializeModule(ModuleInfo moduleInfo) at Microsoft.Practices.Composite.Modularity.ModuleManager.LoadModulesThatAreReadyForLoad() at Microsoft.Practices.Composite.Modularity.ModuleManager.OnModuleTypeLoaded(ModuleInfo typeLoadedModuleInfo, Exception error) at Microsoft.Practices.Composite.Modularity.FileModuleTypeLoader.BeginLoadModuleType(ModuleInfo moduleInfo, ModuleTypeLoadedCallback callback) at Microsoft.Practices.Composite.Modularity.ModuleManager.BeginRetrievingModule(ModuleInfo moduleInfo) at Microsoft.Practices.Composite.Modularity.ModuleManager.LoadModuleTypes(IEnumerable`1 moduleInfos) at Microsoft.Practices.Composite.Modularity.ModuleManager.LoadModulesWhenAvailable() at Microsoft.Practices.Composite.Modularity.ModuleManager.Run() at Microsoft.Practices.Composite.UnityExtensions.UnityBootstrapper.InitializeModules() at Infinity.Bootstrapper.InitializeModules() in D:\Projects\dotNet\Infinity\source\Inifinty\Infinity\Application Modules\BootStrapper.cs:line 75 at Microsoft.Practices.Composite.UnityExtensions.UnityBootstrapper.Run(Boolean runWithDefaultConfiguration) at Microsoft.Practices.Composite.UnityExtensions.UnityBootstrapper.Run() at Infinity.App.Application_Startup(Object sender, StartupEventArgs e) in D:\Projects\dotNet\Infinity\source\Inifinty\Infinity\App.xaml.cs:line 37 at System.Windows.Application.OnStartup(StartupEventArgs e) at System.Windows.Application.<.ctorb__0(Object unused) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) 2) Exception Information Exception Type: Microsoft.Practices.ServiceLocation.ActivationException Message: Activation error occured while trying to get instance of type AdminModule, key "" Data: System.Collections.ListDictionaryInternal TargetSite: System.Object GetInstance(System.Type, System.String) HelpLink: NULL Source: Microsoft.Practices.ServiceLocation StackTrace Information at Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance(Type serviceType, String key) at Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance(Type serviceType) at Microsoft.Practices.Composite.Modularity.ModuleInitializer.CreateModule(String typeName) at Microsoft.Practices.Composite.Modularity.ModuleInitializer.Initialize(ModuleInfo moduleInfo) 3) Exception Information Exception Type: Microsoft.Practices.Unity.ResolutionFailedException TypeRequested: AdminModule NameRequested: NULL Message: Resolution of the dependency failed, type = "Infinity.Modules.Admin.AdminModule", name = "". Exception message is: The current build operation (build key Build Key[Infinity.Modules.Admin.AdminModule, null]) failed: The parameter screenFactoryRegistry could not be resolved when attempting to call constructor Infinity.Modules.Admin.AdminModule(Microsoft.Practices.Unity.IUnityContainer container, PhoenixIT.IScreenFactoryRegistry screenFactoryRegistry, Microsoft.Practices.Composite.Events.IEventAggregator eventAggregator, PhoenixIT.IBusyService busyService). (Strategy type BuildPlanStrategy, index 3) Data: System.Collections.ListDictionaryInternal TargetSite: System.Object DoBuildUp(System.Type, System.Object, System.String) HelpLink: NULL Source: Microsoft.Practices.Unity StackTrace Information at Microsoft.Practices.Unity.UnityContainer.DoBuildUp(Type t, Object existing, String name) at Microsoft.Practices.Unity.UnityContainer.DoBuildUp(Type t, String name) at Microsoft.Practices.Unity.UnityContainer.Resolve(Type t, String name) at Microsoft.Practices.Composite.UnityExtensions.UnityServiceLocatorAdapter.DoGetInstance(Type serviceType, String key) at Microsoft.Practices.ServiceLocation.ServiceLocatorImplBase.GetInstance(Type serviceType, String key) 4) Exception Information Exception Type: Microsoft.Practices.ObjectBuilder2.BuildFailedException ExecutingStrategyTypeName: BuildPlanStrategy ExecutingStrategyIndex: 3 BuildKey: Build Key[Infinity.Modules.Admin.AdminModule, null] Message: The current build operation (build key Build Key[Infinity.Modules.Admin.AdminModule, null]) failed: The parameter screenFactoryRegistry could not be resolved when attempting to call constructor Infinity.Modules.Admin.AdminModule(Microsoft.Practices.Unity.IUnityContainer container, PhoenixIT.IScreenFactoryRegistry screenFactoryRegistry, Microsoft.Practices.Composite.Events.IEventAggregator eventAggregator, PhoenixIT.IBusyService busyService). (Strategy type BuildPlanStrategy, index 3) Data: System.Collections.ListDictionaryInternal TargetSite: System.Object ExecuteBuildUp(Microsoft.Practices.ObjectBuilder2.IBuilderContext) HelpLink: NULL Source: Microsoft.Practices.ObjectBuilder2 StackTrace Information at Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp(IBuilderContext context) at Microsoft.Practices.ObjectBuilder2.Builder.BuildUp(IReadWriteLocator locator, ILifetimeContainer lifetime, IPolicyList policies, IStrategyChain strategies, Object buildKey, Object existing) at Microsoft.Practices.Unity.UnityContainer.DoBuildUp(Type t, Object existing, String name) 5) Exception Information Exception Type: System.InvalidOperationException Message: The parameter screenFactoryRegistry could not be resolved when attempting to call constructor Infinity.Modules.Admin.AdminModule(Microsoft.Practices.Unity.IUnityContainer container, PhoenixIT.IScreenFactoryRegistry screenFactoryRegistry, Microsoft.Practices.Composite.Events.IEventAggregator eventAggregator, PhoenixIT.IBusyService busyService). Data: System.Collections.ListDictionaryInternal TargetSite: Void ThrowForResolutionFailed(System.Exception, System.String, System.String, Microsoft.Practices.ObjectBuilder2.IBuilderContext) HelpLink: NULL Source: Microsoft.Practices.ObjectBuilder2 StackTrace Information at Microsoft.Practices.ObjectBuilder2.DynamicMethodConstructorStrategy.ThrowForResolutionFailed(Exception inner, String parameterName, String constructorSignature, IBuilderContext context) at BuildUp_Infinity.Modules.Admin.AdminModule(IBuilderContext ) at Microsoft.Practices.ObjectBuilder2.DynamicMethodBuildPlan.BuildUp(IBuilderContext context) at Microsoft.Practices.ObjectBuilder2.BuildPlanStrategy.PreBuildUp(IBuilderContext context) at Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp(IBuilderContext context) 6) Exception Information Exception Type: Microsoft.Practices.ObjectBuilder2.BuildFailedException ExecutingStrategyTypeName: BuildPlanStrategy ExecutingStrategyIndex: 3 BuildKey: Build Key[PhoenixIT.IScreenFactoryRegistry, null] Message: The current build operation (build key Build Key[PhoenixIT.IScreenFactoryRegistry, null]) failed: The current type, PhoenixIT.IScreenFactoryRegistry, is an interface and cannot be constructed. Are you missing a type mapping? (Strategy type BuildPlanStrategy, index 3) Data: System.Collections.ListDictionaryInternal TargetSite: System.Object ExecuteBuildUp(Microsoft.Practices.ObjectBuilder2.IBuilderContext) HelpLink: NULL Source: Microsoft.Practices.ObjectBuilder2 StackTrace Information at Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp(IBuilderContext context) at Microsoft.Practices.Unity.ObjectBuilder.NamedTypeDependencyResolverPolicy.Resolve(IBuilderContext context) at BuildUp_Infinity.Modules.Admin.AdminModule(IBuilderContext ) 7) Exception Information Exception Type: System.InvalidOperationException Message: The current type, PhoenixIT.IScreenFactoryRegistry, is an interface and cannot be constructed. Are you missing a type mapping? Data: System.Collections.ListDictionaryInternal TargetSite: Void ThrowForAttemptingToConstructInterface(Microsoft.Practices.ObjectBuilder2.IBuilderContext) HelpLink: NULL Source: Microsoft.Practices.ObjectBuilder2 StackTrace Information at Microsoft.Practices.ObjectBuilder2.DynamicMethodConstructorStrategy.ThrowForAttemptingToConstructInterface(IBuilderContext context) at BuildUp_PhoenixIT.IScreenFactoryRegistry(IBuilderContext ) at Microsoft.Practices.ObjectBuilder2.DynamicMethodBuildPlan.BuildUp(IBuilderContext context) at Microsoft.Practices.ObjectBuilder2.BuildPlanStrategy.PreBuildUp(IBuilderContext context) at Microsoft.Practices.ObjectBuilder2.StrategyChain.ExecuteBuildUp(IBuilderContext context) For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

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• Windows Vista/Win7 Privilege Problem: SeDebugPrivilege & OpenProcess

  - by KevenK

  Everything I've been able to find about escalating to the appropriate privileges for my needs has agreed with my current methods, but the problem exists. I'm hoping maybe someone has some Windows Vista/Win7 internals experience that might shine some light where there is only darkness. I'm sure this will get long, but please bare with me. Context: I'm working on an app that requires accessing the memory of other processes on the current machine. This, obviously, requires administrator rights. It also requires SeDebugPrivilege, which I believe myself to be acquiring correctly, although I question if more privileges aren't necessary and thus the cause of my problems. Code has so far worked successfully on all versions of Windows XP, and on my test Vista32 and Win7x64 environments. Process: Program will Always be run with Administrator Rights. This can be assumed throughout this post. Escalating the current process's Access Token to include SeDebugPrivilege rights. Using EnumProcesses to create a list of current PIDs on the system Opening a handle using OpenProcess with PROCESS_ALL_ACCESS access rights Using ReadProcessMemory to read the memory of the other process. Problem: Everything has been working fine during development and my personal testing (including Windows XP 32 & 64, Windows Vista 32, and Windows 7 x64). However, during a test deployment onto both Windows Vista(32-bit) and Windows 7(64-bit) machines of a colleague, there seems to be a privilege/rights problem with OpenProcess failing with a generic Access Denied error. This occurs both when running as a limited User (as would be expected) and also when run explicitly as Administrator (Right-click Run as Administrator and when run from an Administrator level command prompt). However, this problem has been unreproducible for myself in my test environment. I have witnessed the problem first hand, so I trust that the problem exists. The only difference that I can discern between the actual environment and my test environment is that the actual error is occurring when using a Domain Administrator account at the UAC prompt, whereas my tests (which work with no errors) use a local administrator account at the UAC prompt. It appears that although the credentials being used allow UAC to 'run as administrator', the process is still not obtaining the correct rights to be able to OpenProcess on another process. I am not familiar enough with the internals of Vista/Win7 to know what this might be, and I am hoping someone has an idea of what could be the cause. The Kicker: The person who has reported this error, and who's environment can regularly reproduce this bug, has a small application named along the lines of RunWithDebugEnabled which is a small bootstrap program which appears to escalate its own privileges and then launch the executable passed to it (thus inheriting the escalated privileges). When run with this program, using the same Domain Administrator credentials at UAC prompt, the program works correctly and is able to successfully call OpenProcess and operates as intended. So this is definitely a problem with acquiring the correct privileges, and it is known that the Domain Administrator account is an administrator account that should be able to access the correct rights. (Obviously obtaining this source code would be great, but I wouldn't be here if that were possible). Notes: As noted, the errors reported by the failed OpenProcess attempts are Access Denied. According to MSDN documentation of OpenProcess: If the caller has enabled the SeDebugPrivilege privilege, the requested access is granted regardless of the contents of the security descriptor. This leads me to believe that perhaps there is a problem under these conditions either with (1) Obtaining SeDebugPrivileges or (2) Requiring other privileges which have not been mentioned in any MSDN documentation, and which might differ between a Domain Administrator account and a Local Administrator account Sample Code: void sample() { ///////////////////////////////////////////////////////// // Note: Enabling SeDebugPrivilege adapted from sample // MSDN @ http://msdn.microsoft.com/en-us/library/aa446619%28VS.85%29.aspx // Enable SeDebugPrivilege HANDLE hToken = NULL; TOKEN_PRIVILEGES tokenPriv; LUID luidDebug; if(OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES, &hToken) != FALSE) { if(LookupPrivilegeValue(NULL, SE_DEBUG_NAME, &luidDebug) != FALSE) { tokenPriv.PrivilegeCount = 1; tokenPriv.Privileges[0].Luid = luidDebug; tokenPriv.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED; if(AdjustTokenPrivileges(hToken, FALSE, &tokenPriv, 0, NULL, NULL) != FALSE) { // Always successful, even in the cases which lead to OpenProcess failure cout << "SUCCESSFULLY CHANGED TOKEN PRIVILEGES" << endl; } else { cout << "FAILED TO CHANGE TOKEN PRIVILEGES, CODE: " << GetLastError() << endl; } } } CloseHandle(hToken); // Enable SeDebugPrivilege ///////////////////////////////////////////////////////// vector<DWORD> pidList = getPIDs(); // Method that simply enumerates all current process IDs ///////////////////////////////////////////////////////// // Attempt to open processes for(int i = 0; i < pidList.size(); ++i) { HANDLE hProcess = NULL; hProcess = OpenProcess(PROCESS_ALL_ACCESS, FALSE, pidList[i]); if(hProcess == NULL) { // Error is occurring here under the given conditions cout << "Error opening process PID(" << pidList[i] << "): " << GetLastError() << endl; } CloseHandle(hProcess); } // Attempt to open processes ///////////////////////////////////////////////////////// } Thanks! If anyone has some insight into what possible permissions/privileges/rights/etc that I may be missing to correctly open another process (Assuming the executable has been properly "Run as Administrator"ed) on Windows Vista and Windows 7 under the above conditions, it would be most greatly appreciated. I wouldn't be here if I weren't absolutely stumped, but I'm hopeful that once again the experience and knowledge of the group shines bright. I thank you for taking the time to read this wall of text. The good intentions alone are appreciated, thanks for being the type of person that makes SO so useful to all!

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• Routing Issue in ASP.NET MVC 3 RC 2

  - by imran_ku07

       Introduction:             Two weeks ago, ASP.NET MVC team shipped the ASP.NET MVC 3 RC 2 release. This release includes some new features and some performance optimization. This release also fixes most of the bugs but still some minor issues are present in this release. Some of these issues are already discussed by Scott Guthrie at Update on ASP.NET MVC 3 RC2 (and a workaround for a bug in it). In addition to these issues, I have found another issue in this release regarding routing. In this article, I will show you the issue regarding routing and a simple workaround for this issue.       Description:             The easiest way to understand an issue is to reproduce it in the application. So create a MVC 2 application and a MVC 3 RC 2 application. Then in both applications, just open global.asax file and update the default route as below,     routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( "Default", // Route name "{controller}/{action}/{id1}/{id2}", // URL with parameters new { controller = "Home", action = "Index", id1 = UrlParameter.Optional, id2 = UrlParameter.Optional } // Parameter defaults );              Then just open Index View and add the following lines,    <%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server"> Home Page </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <% Html.RenderAction("About"); %> </asp:Content>             The above view will issue a child request to About action method. Now run both applications. ASP.NET MVC 2 application will run just fine. But ASP.NET MVC 3 RC 2 application will throw an exception as shown below,                  You may think that this is a routing issue but this is not the case here as both ASP.NET MVC 2 and ASP.NET MVC  3 RC 2 applications(created above) are built with .NET Framework 4.0 and both will use the same routing defined in System.Web. Something is wrong in ASP.NET MVC 3 RC 2. So after digging into ASP.NET MVC source code, I have found that the UrlParameter class in ASP.NET MVC 3 RC 2 overrides the ToString method which simply return an empty string.     public sealed class UrlParameter { public static readonly UrlParameter Optional = new UrlParameter(); private UrlParameter() { } public override string ToString() { return string.Empty; } }             In MVC 2 the ToString method was not overridden. So to quickly fix the above problem just replace UrlParameter.Optional default value with a different value other than null or empty(for example, a single white space) or replace UrlParameter.Optional default value with a new class object containing the same code as UrlParameter class have except the ToString method is not overridden (or with a overridden ToString method that return a string value other than null or empty). But by doing this you will loose the benefit of ASP.NET MVC 2 Optional URL Parameters. There may be many different ways to fix the above problem and not loose the benefit of optional parameters. Here I will create a new class MyUrlParameter with the same code as UrlParameter class have except the ToString method is not overridden. Then I will create a base controller class which contains a constructor to remove all MyUrlParameter route data parameters, same like ASP.NET MVC doing with UrlParameter route data parameters early in the request.     public class BaseController : Controller { public BaseController() { if (System.Web.HttpContext.Current.CurrentHandler is MvcHandler) { RouteValueDictionary rvd = ((MvcHandler)System.Web.HttpContext.Current.CurrentHandler).RequestContext.RouteData.Values; string[] matchingKeys = (from entry in rvd where entry.Value == MyUrlParameter.Optional select entry.Key).ToArray(); foreach (string key in matchingKeys) { rvd.Remove(key); } } } } public class HomeController : BaseController { public ActionResult Index(string id1) { ViewBag.Message = "Welcome to ASP.NET MVC!"; return View(); } public ActionResult About() { return Content("Child Request Contents"); } }     public sealed class MyUrlParameter { public static readonly MyUrlParameter Optional = new MyUrlParameter(); private MyUrlParameter() { } }     routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); routes.MapRoute( "Default", // Route name "{controller}/{action}/{id1}/{id2}", // URL with parameters new { controller = "Home", action = "Index", id1 = MyUrlParameter.Optional, id2 = MyUrlParameter.Optional } // Parameter defaults );             MyUrlParameter class is a copy of UrlParameter class except that MyUrlParameter class not overrides the ToString method. Note that the default route is modified to use MyUrlParameter.Optional instead of UrlParameter.Optional. Also note that BaseController class constructor is removing MyUrlParameter parameters from the current request route data so that the model binder will not bind these parameters with action method parameters. Now just run the ASP.NET MVC 3 RC 2 application again, you will find that it runs just fine.             In case if you are curious to know that why ASP.NET MVC 3 RC 2 application throws an exception if UrlParameter class contains a ToString method which returns an empty string, then you need to know something about a feature of routing for url generation. During url generation, routing will call the ParsedRoute.Bind method internally. This method includes a logic to match the route and build the url. During building the url, ParsedRoute.Bind method will call the ToString method of the route values(in our case this will call the UrlParameter.ToString method) and then append the returned value into url. This method includes a logic after appending the returned value into url that if two continuous returned values are empty then don't match the current route otherwise an incorrect url will be generated. Here is the snippet from ParsedRoute.Bind method which will prove this statement.       if ((builder2.Length > 0) && (builder2[builder2.Length - 1] == '/')) { return null; } builder2.Append("/"); ........................................................... ........................................................... ........................................................... ........................................................... if (RoutePartsEqual(obj3, obj4)) { builder2.Append(UrlEncode(Convert.ToString(obj3, CultureInfo.InvariantCulture))); continue; }             In the above example, both id1 and id2 parameters default values are set to UrlParameter object and UrlParameter class include a ToString method that returns an empty string. That's why this route will not matched.            Summary:             In this article I showed you the issue regarding routing and also showed you how to workaround this problem. I explained this issue with an example by creating a ASP.NET MVC 2 and a ASP.NET MVC 3 RC 2 application. Finally I also explained the reason for this issue. Hopefully you will enjoy this article too.   SyntaxHighlighter.all()

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• Launching a WPF Window in a Separate Thread, Part 1

  - by Reed

  Typically, I strongly recommend keeping the user interface within an application’s main thread, and using multiple threads to move the actual “work” into background threads.  However, there are rare times when creating a separate, dedicated thread for a Window can be beneficial.  This is even acknowledged in the MSDN samples, such as the Multiple Windows, Multiple Threads sample.  However, doing this correctly is difficult.  Even the referenced MSDN sample has major flaws, and will fail horribly in certain scenarios.  To ease this, I wrote a small class that alleviates some of the difficulties involved. The MSDN Multiple Windows, Multiple Threads Sample shows how to launch a new thread with a WPF Window, and will work in most cases.  The sample code (commented and slightly modified) works out to the following: // Create a thread Thread newWindowThread = new Thread(new ThreadStart( () => { // Create and show the Window Window1 tempWindow = new Window1(); tempWindow.Show(); // Start the Dispatcher Processing System.Windows.Threading.Dispatcher.Run(); })); // Set the apartment state newWindowThread.SetApartmentState(ApartmentState.STA); // Make the thread a background thread newWindowThread.IsBackground = true; // Start the thread newWindowThread.Start(); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This sample creates a thread, marks it as single threaded apartment state, and starts the Dispatcher on that thread. That is the minimum requirements to get a Window displaying and handling messages correctly, but, unfortunately, has some serious flaws. The first issue – the created thread will run continuously until the application shuts down, given the code in the sample.  The problem is that the ThreadStart delegate used ends with running the Dispatcher.  However, nothing ever stops the Dispatcher processing.  The thread was created as a Background thread, which prevents it from keeping the application alive, but the Dispatcher will continue to pump dispatcher frames until the application shuts down. In order to fix this, we need to call Dispatcher.InvokeShutdown after the Window is closed.  This would require modifying the above sample to subscribe to the Window’s Closed event, and, at that point, shutdown the Dispatcher: // Create a thread Thread newWindowThread = new Thread(new ThreadStart( () => { Window1 tempWindow = new Window1(); // When the window closes, shut down the dispatcher tempWindow.Closed += (s,e) => Dispatcher.CurrentDispatcher.BeginInvokeShutdown(DispatcherPriority.Background); tempWindow.Show(); // Start the Dispatcher Processing System.Windows.Threading.Dispatcher.Run(); })); // Setup and start thread as before This eliminates the first issue.  Now, when the Window is closed, the new thread’s Dispatcher will shut itself down, which in turn will cause the thread to complete. The above code will work correctly for most situations.  However, there is still a potential problem which could arise depending on the content of the Window1 class.  This is particularly nasty, as the code could easily work for most windows, but fail on others. The problem is, at the point where the Window is constructed, there is no active SynchronizationContext.  This is unlikely to be a problem in most cases, but is an absolute requirement if there is code within the constructor of Window1 which relies on a context being in place. While this sounds like an edge case, it’s fairly common.  For example, if a BackgroundWorker is started within the constructor, or a TaskScheduler is built using TaskScheduler.FromCurrentSynchronizationContext() with the expectation of synchronizing work to the UI thread, an exception will be raised at some point.  Both of these classes rely on the existence of a proper context being installed to SynchronizationContext.Current, which happens automatically, but not until Dispatcher.Run is called.  In the above case, SynchronizationContext.Current will return null during the Window’s construction, which can cause exceptions to occur or unexpected behavior. Luckily, this is fairly easy to correct.  We need to do three things, in order, prior to creating our Window: Create and initialize the Dispatcher for the new thread manually Create a synchronization context for the thread which uses the Dispatcher Install the synchronization context Creating the Dispatcher is quite simple – The Dispatcher.CurrentDispatcher property gets the current thread’s Dispatcher and “creates a new Dispatcher if one is not already associated with the thread.”  Once we have the correct Dispatcher, we can create a SynchronizationContext which uses the dispatcher by creating a DispatcherSynchronizationContext.  Finally, this synchronization context can be installed as the current thread’s context via SynchronizationContext.SetSynchronizationContext.  These three steps can easily be added to the above via a single line of code: // Create a thread Thread newWindowThread = new Thread(new ThreadStart( () => { // Create our context, and install it: SynchronizationContext.SetSynchronizationContext( new DispatcherSynchronizationContext( Dispatcher.CurrentDispatcher)); Window1 tempWindow = new Window1(); // When the window closes, shut down the dispatcher tempWindow.Closed += (s,e) => Dispatcher.CurrentDispatcher.BeginInvokeShutdown(DispatcherPriority.Background); tempWindow.Show(); // Start the Dispatcher Processing System.Windows.Threading.Dispatcher.Run(); })); // Setup and start thread as before This now forces the synchronization context to be in place before the Window is created and correctly shuts down the Dispatcher when the window closes. However, there are quite a few steps.  In my next post, I’ll show how to make this operation more reusable by creating a class with a far simpler API…

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