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  • SocketChannel in Java sends data, but it doesn't get to destination application

    - by Peterson
    Hi Everybody, I'm suffering a lot to create a simple ChatServer in Java, using the NIO libraries. Wonder if someone could help me. I am doing that by using SocketChannel and Selector to handle multiple clients in a single thread. The problem is: I am able to accept new connections and get it's data, but when I try to send data back, the SocketChannel simply doesn't work. In the method write(), it returns a integer that is the same size of the data i'm passing to it, but the client never receives that data. Strangely, when I close the server application, the client receives the data. It's like the socketchannel maintains a buffer, and it only get flushed when I close the application. Here are some more details, to give you more information to help. I'm handling the events in this piece of code: private void run() throws IOException { ServerSocketChannel ssc = ServerSocketChannel.open(); // Set it to non-blocking, so we can use select ssc.configureBlocking( false ); // Get the Socket connected to this channel, and bind it // to the listening port this.serverSocket = ssc.socket(); InetSocketAddress isa = new InetSocketAddress( this.port ); serverSocket.bind( isa ); // Create a new Selector for selecting this.masterSelector = Selector.open(); // Register the ServerSocketChannel, so we can // listen for incoming connections ssc.register( masterSelector, SelectionKey.OP_ACCEPT ); while (true) { // See if we've had any activity -- either // an incoming connection, or incoming data on an // existing connection int num = masterSelector.select(); // If we don't have any activity, loop around and wait // again if (num == 0) { continue; } // Get the keys corresponding to the activity // that has been detected, and process them // one by one Set keys = masterSelector.selectedKeys(); Iterator it = keys.iterator(); while (it.hasNext()) { // Get a key representing one of bits of I/O // activity SelectionKey key = (SelectionKey)it.next(); // What kind of activity is it? if ((key.readyOps() & SelectionKey.OP_ACCEPT) == SelectionKey.OP_ACCEPT) { // Aceita a conexão Socket s = serverSocket.accept(); System.out.println( "LOG: Conexao TCP aceita de " + s.getInetAddress() + ":" + s.getPort() ); // Make sure to make it non-blocking, so we can // use a selector on it. SocketChannel sc = s.getChannel(); sc.configureBlocking( false ); // Registra a conexao no seletor, apenas para leitura sc.register( masterSelector, SelectionKey.OP_READ ); } else if ( key.isReadable() ) { SocketChannel sc = null; // It's incoming data on a connection, so // process it sc = (SocketChannel)key.channel(); // Verifica se a conexão corresponde a um cliente já existente if((clientsMap.getClient(key)) != null){ boolean closedConnection = !processIncomingClientData(key); if(closedConnection){ int id = clientsMap.getClient(key); closeClient(id); } } else { boolean clientAccepted = processIncomingDataFromNewClient(key); if(!clientAccepted){ // Se o cliente não foi aceito, sua conexão é simplesmente fechada sc.socket().close(); sc.close(); key.cancel(); } } } } // We remove the selected keys, because we've dealt // with them. keys.clear(); } } This piece of code is simply handles new clients that wants to connect to the chat. So, a client makes a TCP connection to the server, and once it gets accepted, it sends data to the server following a simply text protocol, informing his id and asking to get registrated to the server. I handle this in the method processIncomingDataFromNewClient(key). I'm also keeping a map of clients and its connections in a data structure similar to a hashtable. I? doing that because I need to recover a client Id from a connection and a connection from a client Id. This is can be shown in: clientsMap.getClient(key). But the problem itself resides in the method processIncomingDataFromNewClient(key). There, I simply read the data that the client sent to me, validate it, and if it's ok, I send a message back to the client to tell that it is connected to the chat server. Here is a similar piece of code: private boolean processIncomingDataFromNewClient(SelectionKey key){ SocketChannel sc = (SocketChannel) key.channel(); String connectionOrigin = sc.socket().getInetAddress() + ":" + sc.socket().getPort(); int id = 0; //id of the client buf.clear(); int bytesRead = 0; try { bytesRead = sc.read(buf); if(bytesRead<=0){ System.out.println("Conexão fechada pelo: " + connectionOrigin); return false; } System.out.println("LOG: " + bytesRead + " bytes lidos de " + connectionOrigin); String msg = new String(buf.array(),0,bytesRead); // Do validations with the client sent me here // gets the client id }catch (Exception e) { e.printStackTrace(); System.out.println("LOG: Oops. Cliente não conhece o protocolo. Fechando a conexão: " + connectionOrigin); System.out.println("LOG: Primeiros 10 caracteres enviados pelo cliente: " + msg); return false; } } } catch (IOException e) { System.out.println("LOG: Erro ao ler dados da conexao: " + connectionOrigin); System.out.println("LOG: "+ e.getLocalizedMessage()); System.out.println("LOG: Fechando a conexão..."); return false; } // If it gets to here, the protocol is ok and we can add the client boolean inserted = clientsMap.addClient(key, id); if(!inserted){ System.out.println("LOG: Não foi possível adicionar o cliente. Ou ele já está conectado ou já têm clientes demais. Id: " + id); System.out.println("LOG: Fechando a conexão: " + connectionOrigin); return false; } System.out.println("LOG: Novo cliente conectado! Enviando mesnsagem de confirmação. Id: " + id + " Conexao: " + connectionOrigin); /* Here is the error */ sendMessage(id, "Servidor pet: connection accepted"); System.out.println("LOG: Novo cliente conectado! Id: " + id + " Conexao: " + connectionOrigin); return true; } And finally, the method sendMessage(SelectionKey key) looks like this: private void sendMessage(int destId, String msg) { Charset charset = Charset.forName("ISO-8859-1"); CharBuffer charBuffer = CharBuffer.wrap(msg, 0, msg.length()); ByteBuffer bf = charset.encode(charBuffer); //bf.flip(); int bytesSent = 0; SelectionKey key = clientsMap.getClient(destId); SocketChannel sc = (SocketChannel) key.channel(); try { / int total_bytes_sent = 0; while(total_bytes_sent < msg.length()){ bytesSent = sc.write(bf); total_bytes_sent += bytesSent; } System.out.println("LOG: Bytes enviados para o cliente " + destId + ": "+ total_bytes_sent + " Tamanho da mensagem: " + msg.length()); } catch (IOException e) { System.out.println("LOG: Erro ao mandar mensagem para: " + destId); System.out.println("LOG: " + e.getLocalizedMessage()); } } So, what is happening is that the server, when send a message, prints something like this: LOG: Bytes sent to the client: 28 Size of the message: 28 So, it tells that it sent the data, but the chat client keeps blocking, waiting in the recv() method. So, the data never gets to it. When I close the server application, though, all the data appears in the client. I wonder why. It is important to say that the client is in C and the server JAVA, and I'm running both in the same machine, an Ubuntu Guest in virtualbox under windows. I also run both under windows host and under linuxes hosts, and keep getting the same strange problem. I'm sorry for the great lenght of this question, but I already searched a lot of places for an answer, found a lot of tutorials and questions, including here at StackOverflow, but coundn't find a reasonable explanation. I am really not liking this Java NIO, and i saw a lot of people complaining about it too. I am thinking that if I had done that in C it would have been a lot easier :-D So, if someone could help me and even discuss this behavor, it would be great! :-) Thanks everybody in advance, Péterson

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  • Interface Builder error: IBXMLDecoder: The value for key is too large to fit into a 32 bit integer

    - by stdout
    I'm working with Robert Payne's fork of PSMTabBarControl that works with IB 3.2 (thanks BTW Robert!): http://codaset.com/robertjpayne/psmtabbarcontrol/. The demo application works fine on 64-bit systems, but when I try to open the XIB file in Interface Builder on a 32-bit system I get: IBXMLDecoder: The value (4654500848) for key (myTrackingRectTag) is too large to fit into a 32 bit integer Building the app as 32 bit works, but then running it gives: PSMTabBarControlDemo[9073:80f] * -[NSKeyedUnarchiver decodeInt32ForKey:]: value (4654500848) for key (myTrackingRectTag) too large to fit in 32-bit integer Not sure if this is a generic IB issue that can occur when moving between 64 and 32 bit systems, or if this is a more specific issue with this code. Has anyone else run into this?

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  • Simple way to use Foreign Key values for sorting?

    - by Brian Rizzo
    Disclaimer: I jumped to C# 2008 recently and SubSonic 3 (3.0.0.4) at the same time. I haven't used Linq for much of anything in the past. Is there an easy way to use the foreign key display value for sorting, rather than the FK Id (which is numeric)? I've added a new Find method in my ActiveRecord.tt to help with sorting based on a string field name but after doing some testing I realized that even though its working as it should be, I am not handling foreign key fields at all (they are just sorting by their value). Even if I need to change how I am accessing the data it is early enough in the project to do that. Just looking for suggestions.

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  • How to Key-Value-Observe the rotation of a CALayer?

    - by HelloMoon
    I can access the value like this: NSNumber* rotationZ = [myLayer valueForKeyPath:@"transform.rotation.z"]; But for some reason, if I try to KV-observe that key path, I get a compiler error. First, this is how I try to do it: [myLayer addObserver:self forKeyPath:@"transform.rotation.z" options:0 context:nil]; The compiler tells me: *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[ addObserver: forKeyPath:@"rotation.z" options:0x0 context:0x528890] was sent to an object that is not KVC-compliant for the "rotation" property.' what I don't get is, why I can access that z value by KVC key path, but not add an observer to it. Does this make sense? How else could I observe the z value of that matrix? I don't care about the other values of the matrix. Only the z rotation. Any other way to access and observe it?

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  • INSERT INTO ... SELECT FROM ... ON DUPLICATE KEY UPDATE

    - by dnagirl
    I'm doing an insert query where most of many columns would need to be updated to the new values if a unique key already existed. It goes something like this: INSERT INTO lee(exp_id, created_by, location, animal, starttime, endtime, entct, inact, inadur, inadist, smlct, smldur, smldist, larct, lardur, lardist, emptyct, emptydur) SELECT id, uid, t.location, t.animal, t.starttime, t.endtime, t.entct, t.inact, t.inadur, t.inadist, t.smlct, t.smldur, t.smldist, t.larct, t.lardur, t.lardist, t.emptyct, t.emptydur FROM tmp t WHERE uid=x ON DUPLICATE KEY UPDATE ...; //update all fields to values from SELECT, except for exp_id, created_by, location, animal, starttime, endtime I'm not sure what the syntax for the UPDATE clause should be. How do I refer to the current row from the SELECT clause?

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  • Is it possible to use array_shift() in PHP and get the key?

    - by alex
    I have a list of files in an array where the filename is the key and the value is the last modified date in seconds. They are sorted from oldest to newest. The files are glob()'d in, and then sorted this way using asort($fileNameToLastModified, SORT_NUMERIC); I use array_shift() to get the oldest file. Unfortunately, it seems to be giving me the value, and there doesn't seem to be a way to get the key. Would the only way to do that be something like this? $keys = array_keys($fileNameToLastModified); $oldest = array_shift($keys); array_shift($fileNameToLastModified); // to manually chop the first array member off too. Or is there a built in? Thanks

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  • Is it possible to use array_shift() in PHP and get the key?

    - by alex
    I have a list of files in an array where the filename is the key and the value is the last modified date in seconds. They are sorted from oldest to newest. The files are glob()'d in, and then sorted this way using asort($fileNameToLastModified, SORT_NUMERIC); I use array_shift() to get the oldest file. Unfortunately, it seems to be giving me the value, and there doesn't seem to be a way to get the key. Would the only way to do that be something like this? $keys = array_keys($fileNameToLastModified); $oldest = array_shift($keys); array_shift($fileNameToLastModified); // to manually chop the first array member off too. Or is there a built in? Thanks

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  • Mapping one to one foreign key relationships in Entity Framework 4.0?

    - by John K.
    Hello all, I'm sure I'm missing something very simple, but let's say I have two entities, Employee and EmployeeType. Employee type would contain values like 'Full time', 'Contractor', 'Intern', etc. An Employee entity would contain one, and only one EmployeeType value. So I am designing a new .edmx model using the Model-First approach and generating my actual sql server data schema from the model. I want to add an integer type foreign key id into my Employee entity, EmployeeTypeId, which will map to the primary key of the EmployeeType entity. So I've gone ahead and done that in my Employee entity. Where I'm stuck is how, though the Entity Framework designer, to enforce the 1:1 referential constraint on that EmployeeTypeId property? Or does the EF handle that automatically behind the scenes? thanks in advance, John

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  • MSCRYPTO: How to import RSA key from pkcs#12 into Microsoft Enhanced RSA and AES CSP?

    - by lsh123
    According to the MSDN (http://msdn.microsoft.com/en-us/library/aa387314%28v=VS.85%29.aspx) the PFXImportCertStore function imports the cert/key into Base CSP (MS_STRONG_PROV) or Enhanced CSP (MS_ENHANCED_PROV). However, to use RSA/SHA2 signatures, I need to import the key into the Enhanced RSA and AES CSP (MS_ENH_RSA_AES_PROV) and I can't find a way to do it. The documentation mentions "provider name" from the PFX packet, but I can't find any way to set it for a pkcs12 file generated by a 3rd party (e.g. OpenSSL). Thank you in advance.

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  • C#: Replicating keyboard shortcuts in textbox, how do I prevent the beep sound caused by alt key pre

    - by Michael Johnson
    I'm creating a routine that allows the user to replicate keyboard shortcuts into a textbox for 'custom keyboard shortcuts' customization, but everytime the alt key is pressed with another letter, it produces another sound. I'm capturing the keys in the textbox_keydown event to parse the modifiers + other keys into a readable Shift + A or Ctrl + Shift + B manner into that very same textbox. Should I be doing this in a different event like textbox_previewkey instead of textbox_keydown? How can I prevent the alt modifier key + a letter or number causing the Beep sound? the textbox is just a normal .net 3.5 textbox with the only edited properties of it being the ReadOnly property to false. Is there a better way I could re-do this? I'm currently just checking that if any modifiers keys are pressed and then + a-z or 0-9, then to go ahead and input the appropriately pressed keys into that same textbox like Shift + A or Ctrl + Shift + Y.

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  • Mysql 'On Duplicate Key INSERT .... SELECT...'

    - by calumbrodie
    Hi, I'm looking for a way to do the following in mysql. INSERT INTO category (cat_id,sku,description,color) VALUES ('$cat_id','$sku','$description','$color') ON DUPLICATE KEY UPDATE description=$description" this works fine... but I want something further to happen if there is a duplicate key. I want to copy a row from the 'product' table to the 'categorized_products'... AND INSERT categorized_products (a,b,c) SELECT a,b,c FROM products WHERE products.cat = '$cat_id' is there a way to do the INSERT...SELECT as part of the first query or do I need to evaluate the above with mysql_affected_rows ( 1 is updated and == 1 is inserted) and then run my second query. Obviously the above will work but means another query and more LOC. Thanks!

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  • Perl : how to interrupt/resume loop by user hitting a key?

    - by Michael Mao
    Hi all: This is for debugging purpose. I've got a for loop that generates some output to Cygwin bash's CLI. I know that I can redirect outputs to text files and use Perl or even just a normal text editor to inspect the values printed out for a particular iteration, just feel that a bit painful. What I am now thinking is, to place a special subroutine inside the for loop, so that it would be "interrupted" at the beginning of each iteration, and Perl script should only resume to run after user/programmer hits a key(the Enter Key from keyboard?) In this way I can directly inspect the values printed out during each iteration. Is there a simple way to do this, without using additional libraries/CPAN ? Many thanks to the hints/suggestions in advance.

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  • How to compare if string has a enter key in the end using jquery/javascript?

    - by user144842
    I have a string value from a user input box. I have to figure out if last char is a enter key (line feed). Thats the code. Here I am checking if last char has a whitespace. Now I also have to check if last char is enter key (carriage return or line feed). How can i do this? var txt = $get("<%= txtUserText.ClientID %>"); if (txt.value.substring(txt.value.length -1) !== ' ' || <checkifLastCharIsEnterKey>) //my code to take action **I don't think i need a keypress or keyup event because this above piece of code is not invoked at the time of user input.

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  • How to prevent the beep sound caused by alt key pressed in a WinForms TextBox?

    - by Michael Johnson
    I'm creating a routine that allows the user to replicate keyboard shortcuts into a textbox for 'custom keyboard shortcuts' customization, but every time the alt key is pressed with another letter, it produces another sound. I'm capturing the keys in the textbox_keydown event to parse the modifiers + other keys into a readable Shift + A or Ctrl + Shift + B manner into that very same textbox. Should I be doing this in a different event like textbox_previewkey instead of textbox_keydown? How can I prevent the alt modifier key + a letter or number causing the Beep sound? the textbox is just a normal .net 3.5 textbox with the only edited properties of it being the ReadOnly property to false. Is there a better way I could re-do this? I'm currently just checking that if any modifiers keys are pressed and then + a-z or 0-9, then to go ahead and input the appropriately pressed keys into that same textbox like Shift + A or Ctrl + Shift + Y.

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  • Is it possible to invoke NSDictionary's valueForKeyPath: when a key contains periods?

    - by Jonukas
    I'm trying to get the value of the repeatInterval key in the com.apple.scheduler plist. I'd like to just use NSDictionary's valueForKeyPath: method like so: CFPropertyListRef value; value = CFPreferencesCopyValue(CFSTR("AbsoluteSchedule"), CFSTR("com.apple.scheduler"), kCFPreferencesCurrentUser, kCFPreferencesCurrentHost); NSNumber *repeatInterval = [(NSDictionary *)value valueForKeyPath:@"com.apple.SoftwareUpdate.SUCheckSchedulerTag.Timer.repeatInterval"]; But the problem with this is that the first key is really "com.apple.SoftwareUpdate", not just "com". I can get around this by getting that first value separately: NSDictionary *dict = [(NSDictionary *)value valueForKey:@"com.apple.SoftwareUpdate"]; NSNumber *repeatInterval = [dict valueForKeyPath:@"SUCheckSchedulerTag.Timer.repeatInterval"]; I just wanted to know if there is a way to escape periods in a keypath so I can eliminate this extra step.

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  • sqlalchemy: what is the difference between declaring the cascade within the foreign key vs relation?

    - by steve
    what is the difference between declaring the cascade within a foreign key vs relations? class Contact(Base): __tablename__ = 'contacts' id = Column(Integer, primary_key=True) addresses = relation("Address", backref="contact") class Address(Base): __tablename__ = 'addresses' id = Column(Integer, primary_key=True) contact_id = Column(Integer, ForeignKey('contact.id', onupdate="CASCADE", ondelete="CASCADE"))) vs class Contact(Base): __tablename__ = 'contacts' id = Column(Integer, primary_key=True) addresses = relation("Address", backref="contact", cascade="all, delete-orphan") class Address(Base): __tablename__ = 'addresses' id = Column(Integer, primary_key=True) contact_id = Column(Integer, ForeignKey('contact.id')) with the foreign key declaration, it seems like the cascade is enforced at the database level. how does the relations approach work? thanks!

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  • Android on TabHost little more depth of the problem, there is the hard return key on the treatment.

    - by user365723
    Hello everybody, I have a question on the Android Activity, for example I have a TabHost, and there are included four Activities, the first tab is a search Activity, enter a keyword in the current result of this Activity to return, and in the current Activity display. Is called to display the search results themselves. And after searching several times, and then return to key mobile phone keypad, the display is the result of the last search keyword, I want the press back key to return to the last call of the Activity or TabHost. Should I do? By the way, in a tab in the use of Intent calls a Activity, eg: host.addTab (host.newTabSpec ("friend"). setIndicator ("search") . SetContent (new Intent (this, Search.class))); In this Activity in the need to call another Activity, e.g: startActivity (new Intent (this, Other.class)); Also called another Activity displayed on this tab, but not yet jump out of the show. I ask how you can achieve this?

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  • Why does std::map operator[] create an object if the key doesn't exist?

    - by n1ck
    Hi, I'm pretty sure I already saw this question somewhere (comp.lang.c++? Google doesn't seem to find it there either) but a quick search here doesn't seem to find it so here it is: Why does the std::map operator[] create an object if the key doesn't exist? I don't know but for me this seems counter-intuitive if you compare to most other operator[] (like std::vector) where if you use it you must be sure that the index exists. I'm wondering what's the rationale for implementing this behavior in std::map. Like I said wouldn't it be more intuitive to act more like an index in a vector and crash (well undefined behavior I guess) when accessed with an invalid key? Refining my question after seeing the answers: Ok so far I got a lot of answers saying basically it's cheap so why not or things similar. I totally agree with that but why not use a dedicated function for that (I think one of the comment said that in java there is no operator[] and the function is called put)? My point is why doesn't map operator[] work like a vector? If I use operator[] on an out of range index on a vector I wouldn't like it to insert an element even if it was cheap because that probably mean an error in my code. My point is why isn't it the same thing with map. I mean, for me, using operator[] on a map would mean: i know this key already exist (for whatever reason, i just inserted it, I have redundancy somewhere, whatever). I think it would be more intuitive that way. That said what are the advantage of doing the current behavior with operator[] (and only for that, I agree that a function with the current behavior should be there, just not operator[])? Maybe it give clearer code that way? I don't know. Another answer was that it already existed that way so why not keep it but then, probably when they (the ones before stl) choose to implement it that way they found it provided an advantage or something? So my question is basically: why choose to implement it that way, meaning a somewhat lack of consistency with other operator[]. What benefit do it give? Thanks

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  • How to use SQL - INSERT...ON DUPLICATE KEY UPDATE?

    - by Probocop
    Hi, I have a script which captures tweets and puts them into a database. I will be running the script on a cronjob and then displaying the tweets on my site from the database to prevent hitting the limit on the twitter API. So I don't want to have duplicate tweets in my database, I understand I can use 'INSERT...ON DUPLICATE KEY UPDATE' to achieve this, but I don't quite understand how to use it. My database structure is as follows. Table - Hash id (auto_increment) tweet user user_url And currently my SQL to insert is as follows: $tweet = $clean_content[0]; $user_url = $clean_uri[0]; $user = $clean_name[0]; $query='INSERT INTO hash (tweet, user, user_url) VALUES ("'.$tweet.'", "'.$user.'", "'.$user_url.'")'; mysql_query($query); How would I correctly use 'INSERT...ON DUPLICATE KEY UPDATE' to insert only if it doesn't exist, and update if it does? Thanks

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  • SSL: can the secret key be sniffed before the actual encryption begins?

    - by Jorre
    I was looking into SSL and some of the steps that are involved to set up an encrypted connection between a server and a client computer. I understand that a server key and certificate is sent to the browser, and that a secret code is being calculated, like they say in the following video: http://www.youtube.com/watch?v=iQsKdtjwtYI around 5:22, they talk about a master secret code that is being calculated to start talking in an encrypted way. My question now is: before the connection is actually encrypted (the handshake phase), all communication between the server and the client can be sniffed by a packet sniffer. Isn't it then possible to sniff the encryption key or other data that is used to set up a secure connection?

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