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• Cross Theaded Calls - Many controls Heavy GUI Application after .net 1.1 2.0 upgrade- best way ??

  - by keepsmilinyaar

  I have recently upgraded a .net1.1 solution to .net2.0. AS this is a very heavy GUI appilcation with loads of controls and many multithreaded operations that update the GUI. While these operations worked seamlessly in .net1.1 it is throwing up Cross Threaded Illegal operations after the upgrade. Considering the fact that tehre are numerous grids, buttons and status labels that need to be updated via these multi threaded operations, I decided to code for checking the InvokeRequired solution, however doing that for every control would probably not be the best way to go about it. I was wondering if you could suggest a better way of how I can go about it or propose any OOPS based class structure that I could code around to make the code look better. Please do let me know if my question is unclear. Thanks in advance

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• Sharing runtime variables between files

  - by nightcracker

  I have a project with a few files that all include the header global.hpp. Those files want to share and update information that is relevant for the whole program during runtime (that data is gathered progressively during the program runs but the fields of data are known at compile-time). Now my idea was to use a struct like this: global.hpp #include <string> #ifndef _GLOBAL_SESSION_STRUCT #define _GLOBAL_SESSION_STRUCT struct session_struct { std::string username; std::string password; std::string hostname; unsigned short port; // more data fields as needed }; #endif extern struct session_struct session; main.cpp #include "global.hpp" struct session_struct session; int main(int argc, char* argv[]) { session.username = "user"; session.password = "secret"; session.hostname = "example.com"; session.port = 80; // other stuff, etc return 0; } Now every file that includes global.hpp can just read & write the fields of the session struct and easily share information. Is this the correct way to do this? NOTE: For this specific project no threading is used. But please (for future projects and other people reading) clarify in your answer how this (or your proposed) solution works when threaded. Also, for this example/project session variables are shared. But this should also apply to any other form of shared variables.

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• How to make double[,] x_List in C#3.0?

  - by Newbie

  I ned to implement the multi-linear regression in C#(3.0) by using the LinESt function of Excel. Basically I am trying to achieve =LINEST(ACL_returns!I2:I10,ACL_returns!J2:K10,FALSE,TRUE) So I have the data as below double[] x1 = new double[] { 0.0330, -0.6463, 0.1226, -0.3304, 0.4764, -0.4159, 0.4209, -0.4070, -0.2090 }; double[] x2 = new double[] { -0.2718, -0.2240, -0.1275, -0.0810, 0.0349, -0.5067, 0.0094, -0.4404, -0.1212 }; double[] y = new double[] { 0.4807, -3.7070, -4.5582, -11.2126, -0.7733, 3.7269, 2.7672, 8.3333, 4.7023 }; I have to write a function whose signature will be Compute(double[,] x_List, double[] y_List) { LinEst(x_List,y_List, true, true); < - This is the excel function that I will call. } My question is how by using double[] x1 and double[] x2 I will make double[,] x_List ? I am using C#3.0 and framework 3.5. Thanks in advance

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• Implementing java FixedTreadPool status listener

  - by InsertNickHere

  Hi there, it's about an application which is supposed to process (VAD, Loudness, Clipping) a lot of soundfiles (e.g. 100k). At this time, I create as many worker threads (callables) as I can put into memory, and then run all with a threadPool.invokeAll(), write results to file system, unload processed files and continue at step 1. Due to the fact it's an app with a GUI, i don't want to user to feel like the app "is not responding" while processing all soundfiles. (which it does at this time cause invokeAll is blocking). Im not sure what is a "good" way to fix this. It shall not be possible for the user to do other things while processing, but I'd like to show a progress bar like "10 of 100000 soundfiles are done". So how do I get there? Do I have to create a "watcher thread", so that every worker hold a callback on it? I'm quite new to multi threading, and don't get the idea of such a mechanisem.. If you need to know: I'm using SWT/JFace. Regards, InsertNickHere

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• How to approach parallel processing of messages?

  - by Dan

  I am redesigning the messaging system for my app to use intel threading building blocks and am stumped trying to decide between two possible approaches. Basically, I have a sequence of message objects and for each message type, a sequence of handlers. For each message object, I apply each handler registered for that message objects type. The sequential version would be something like this (pseudocode): for each message in message_sequence <- SEQUENTIAL for each handler in (handler_table for message.type) apply handler to message <- SEQUENTIAL The first approach which I am considering processes the message objects in turn (sequentially) and applies the handlers concurrently. Pros: predictable ordering of messages (ie, we are guaranteed a FIFO processing order) (potentially) lower latency of processing each message Cons: more processing resources available than handlers for a single message type (bad parallelization) bad use of processor cache since message objects need to be copied for each handler to use large overhead for small handlers The pseudocode of this approach would be as follows: for each message in message_sequence <- SEQUENTIAL parallel_for each handler in (handler_table for message.type) apply handler to message <- PARALLEL The second approach is to process the messages in parallel and apply the handlers to each message sequentially. Pros: better use of processor cache (keeps the message object local to all handlers which will use it) small handlers don't impose as much overhead (as long as there are other handlers also to be run) more messages are expected than there are handlers, so the potential for parallelism is greater Cons: Unpredictable ordering - if message A is sent before message B, they may both be processed at the same time, or B may finish processing before all of A's handlers are finished (order is non-deterministic) The pseudocode is as follows: parallel_for each message in message_sequence <- PARALLEL for each handler in (handler_table for message.type) apply handler to message <- SEQUENTIAL The second approach has more advantages than the first, but non-deterministic ordering is a big disadvantage.. Which approach would you choose and why? Are there any other approaches I should consider (besides the obvious third approach: parallel messages and parallel handlers, which has the disadvantages of both and no real redeeming factors as far as I can tell)? Thanks!

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• Setting the default stack size on Linux globally for the program

  - by wowus

  So I've noticed that the default stack size for threads on linux is 8MB (if I'm wrong, PLEASE correct me), and, incidentally, 1MB on Windows. This is quite bad for my application, as on a 4-core processor that means 64 MB is space is used JUST for threads! The worst part is, I'm never using more than 100kb of stack per thread (I abuse the heap a LOT ;)). My solution right now is to limit the stack size of threads. However, I have no idea how to do this portably. Just for context, I'm using Boost.Thread for my threading needs. I'm okay with a little bit of #ifdef hell, but I'd like to know how to do it easily first. Basically, I want something like this (where windows_* is linked on windows builds, and posix_* is linked under linux builds) // windows_stack_limiter.c int limit_stack_size() { // Windows impl. return 0; } // posix_stack_limiter.c int limit_stack_size() { // Linux impl. return 0; } // stack_limiter.cpp int limit_stack_size(); static volatile int placeholder = limit_stack_size(); How do I flesh out those functions? Or, alternatively, am I just doing this entirely wrong? Remember I have no control over the actual thread creation (no new params to CreateThread on Windows), as I'm using Boost.Thread.

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• How to model my database when using entity framework 4?

  - by Junior Ewing

  Trying to wrap my head around the best approach in modelling a database when we are using Entity Framework 4 as the ORM layer. We are going to use asp.net mvc 2 for the application. Is it worth trying to model using the class diagram modeller that comes with Visual Studio 2010 where you graphically configure your models into the EDMX file and then generate out the database structure? I have run into a bunch of non trivial issues and for complex many to many mappings or multi primary key entities the answer is not that obvious even after poking around a while with the tools. I figure its easy at this point to give up and start modelling the DB using real, working DB modelling tools and then try to generate out the EDMX from the database, rather than trying to do the model first approach.

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• Erlang on a JVM/CLR

  - by Fortyrunner

  I've just started reading Joe Armstrongs book on Erlang and listened to his excellent talk on Software Engineering Radio. Its an interesting language/system and one whose time seems to have come around with the advent of multi-core machines. My question is: what is there to stop it being ported to the JVM or CLR? I realise that both virtual machines aren't setup to run the lightweight processes that Erlang calls for - but couldn't these be simulated by threads? Could we see a lightweight or cutdown version of Erlang on a non Erlang VM?

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• Measuring CPU time per-thread on Windows

  - by Eli Courtwright

  I'm developing a long-running multi-threaded Python application for Windows, and I want the process to know the CPU time that each of its threads has taken. I can get the overall times for the entire process with os.times() but I need to know the per-thread times. I know that there are external tools such as the Sysinternals Process Explorer, but my program itself needs to have this information. If I were on Linux, I look in the /proc filesystem, as described here. If I were writing C code, I'd use the GetThreadTimes call, as described here. So how can I accomplish this on Windows using Python?

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• PHP Socket Server vs node.js: Web Chat

  - by Eliasdx

  I want to program a HTTP WebChat using long-held HTTP requests (Comet), ajax and websockets (depending on the browser used). Userdatabase is in mysql. Chat is written in PHP except maybe the chat stream itself which could also be written in javascript (node.js): I don't want to start a php process per user as there is no good way to send the chat messages between these php childs. So I thought about writing an own socket server in either PHP or node.js which should be able to handle more then 1000 connections (chat users). As a purely web developer (php) I'm not much familiar with sockets as I usually let web server care about connections. The chat messages won't be saved on disk nor in mysql but in RAM as an array or object for best speed. As far as I know there is no way to handle multiple connections at the same time in a single php process (socket server), however you can accept a great amount of socket connections and process them successive in a loop (read and write; incoming message - write to all socket connections). The problem is that there will most-likely be a lag with ~1000 users and mysql operations could slow the whole thing down which will then affect all users. My question is: Can node.js handle a socket server with better performance? Node.js is event-based but I'm not sure if it can process multiple events at the same time (wouldn't that need multi-threading?) or if there is just an event queue. With an event queue it would be just like php: process user after user. I could also spawn a php process per chat room (much less users) but afaik there are singlethreaded IRC servers which are also capable to handle thousands of users. (written in c++ or whatever) so maybe it's also possible in php. I would prefer PHP over Node.js because then the project would be php-only and not a mixture of programming languages. However if Node can process connections simultaneously I'd probably choose it.

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• Marshal managed string[] to unmanaged char**

  - by Vince

  This is my c++ struct (Use Multi-Byte Character Set) typedef struct hookCONFIG { int threadId; HWND destination; const char** gameApps; const char** profilePaths; } HOOKCONFIG; And .Net struct [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)] public struct HOOKCONFIG { public int threadId; public IntPtr destination; // MarshalAs? public string[] gameApps; // MarshalAs? public string[] profilePaths; } I got some problem that how do I marshal the string array? When I access the struct variable "profilePaths" in C++ I got an error like this: An unhandled exception of type 'System.AccessViolationException' occurred in App.exe Additional information: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. MessageBox(0, cfg.profilePaths[0], "Title", MB_OK); // error ... Orz

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• Custom User Management for Google App Engine Java

  - by Gopi

  I am using GAE Java for a multi-user application. There are multiple users with different roles. Each user can login, do some operations and logout. The business restricts me from using Google User Service and I need to implement my own for authentication and session management. Can anyone please share with me how should I go about implementing my own user management? I have read its very tricky to implement own user management. Any pointers in terms of best approaches/ design / existing frameworks if any ? I could see some similar posts but they are for python.

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• JavaScript Array Problem

  - by JasonS

  Hi, This wasn't the question I was going to ask but I have unexpectedly run aground with JavaScript arrays. I come from a PHP background and after looking at a few websites I am none the wiser. I am trying to create a multi-dimensional array. var photos = new Array; var a = 0; $("#photos img").each(function(i) { photos[a]["url"] = this.src; photos[a]["caption"] = this.alt; photos[a]["background"] = this.css('background-color'); a++; }); Error message: photos[a] is undefined. How do I do this. Thanks.

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• Do you use Scimore SQL database ?

  - by Darian Miller

  There's a database engine that looks amazing for a free tool and that is Scimore. Have you had much experience with it? If so, how does it rate..particularly against Firebird? How resilient/self reliant is it? (Meaning how much downtime/maintenance is expected?) The scale out capabilities also look very interesting. I just downloaded it and have been playing around and so far it looks good. I had been looking for an easy to deploy single-user type embedded database (which Scimore has an option) and was toying with MS SQL Compact Edition and SQLite and remembered this database from a trial a few years ago. (Windows platform) I was about ready to settle in on SQLite but started thinking about other projects which are multi-user and wanted to stick with a single solution...which is why I started looking at Firebird as well.

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• Is there any Opensource Browser for touchscreen device ?

  - by Wallah

  I need internet browser on my device which has 4.3 Inch screen with 480x272 resolution, I am using embedded Qt 4.6.2 on embedded linux. Micro-controller has ARM9 with 450 Mhz. Requirements for browser are - Touch Screen Support, Panning ( No Scroll bars) - Single touch Zooming ( No Multi Touch Available). - Fit to screen width support ( No Horizontal Scrolling). - Acid 3 Standard Compliable. - Page loading should be like, display all visible text first and then load and show Images Gradually. Is there any browser which is near to this requirements.

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• ~1 second TcpListener Pending()/AcceptTcpClient() lag

  - by cpf

  Probably just watch this video: http://screencast.com/t/OWE1OWVkO As you see, the delay between a connection being initiated (via telnet or firefox) and my program first getting word of it. Here's the code that waits for the connection public IDLServer(System.Net.IPAddress addr,int port) { Listener = new TcpListener(addr, port); Listener.Server.NoDelay = true;//I added this just for testing, it has no impact Listener.Start(); ConnectionThread = new Thread(ConnectionListener); ConnectionThread.Start(); } private void ConnectionListener() { while (Running) { while (Listener.Pending() == false) { System.Threading.Thread.Sleep(1); }//this is the part with the lag Console.WriteLine("Client available");//from this point on everything runs perfectly fast TcpClient cl = Listener.AcceptTcpClient(); Thread proct = new Thread(new ParameterizedThreadStart(InstanceHandler)); proct.Start(cl); } } (I was having some trouble getting the code into a code block) I've tried a couple different things, could it be I'm using TcpClient/Listener instead of a raw Socket object? It's not a mandatory TCP overhead I know, and I've tried running everything in the same thread, etc.

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• design using a readonly class in c#

  - by edosoft

  Hi Small design question here. I'm trying to develop a calculation app in C#. I have a class, let's call it InputRecord, which holds 100s of fields (multi dimensional arrays) This InputRecordclass will be used in a number of CalculationEngines. Each CalculcationEngine can make changes to a number of fields in the InputRecord. These changes are steps needed for it's calculation. Now I don't want the local changes made to the InputRecord to be used in other CalculcationEngine's classes. The first solution that comes to mind is using a struct: these are value types. However I'd like to use inheritance: each CalculationEngine needs a few fields only relevant to that engine: it's has it's own InputRecord, based on BaseInputRecord. Can anyone point me to a design that will help me accomplish this?

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• Audio Player with Custom Buttons

  - by Bryan Wong

  I am developing a website but require help regarding a simple javascript audio player. Currently, I have four divs set up as the "buttons" : previous song; pause; play; and next song. Pretty much self explanatory, each button serves its obvious function, previous song, pause the song, play the song, and next song. With this in mind, I am also hoping to have the music start playing right after the page completes loading. I understand there are numerous javascript solutions that involve the use of third-party "applications" such as jplayer, however, I am not well learned in javascript and would like to request the aid of the general body in this matter. LOL. that was awkwardly formal. Um, but yes. I am looking for a way to use my four divs as the controllers of a multi-track audio player. Thanks,

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• Is there a standard pattern for scanning a job table executing some actions?

  - by Howiecamp

  (I realize that my title is poor. If after reading the question you have an improvement in mind, please either edit it or tell me and I'll change it.) I have the relatively common scenario of a job table which has 1 row for some thing that needs to be done. For example, it could be a list of emails to be sent. The table looks something like this: ID Completed TimeCompleted anything else... ---- --------- ------------- ---------------- 1 No blabla 2 No blabla 3 Yes 01:04:22 ... I'm looking either for a standard practice/pattern (or code - C#/SQL Server preferred) for periodically "scanning" (I use the term "scanning" very loosely) this table, finding the not-completed items, doing the action and then marking them completed once done successfully. In addition to the basic process for accomplishing the above, I'm considering the following requirements: I'd like some means of "scaling linearly", e.g. running multiple "worker processes" simultaneously or threading or whatever. (Just a specific technical thought - I'm assuming that as a result of this requirement, I need some method of marking an item as "in progress" to avoid attempting the action multiple times.) Each item in the table should only be executed once. Some other thoughts: I'm not particularly concerned with the implementation being done in the database (e.g. in T-SQL or PL/SQL code) vs. some external program code (e.g. a standalone executable or some action triggered by a web page) which is executed against the database Whether the "doing the action" part is done synchronously or asynchronously is not something I'm considering as part of this question.

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• Why people don't use LabView for purposes other than data acquisition and virtualization?

  - by Anzurio

  This is marked as a subjective question, I hope I won't get too many down votes though. LV seems to offer a nice graphic alternative to traditional text based programming. As I understand, it's not a just-virtualization/data acquisition programming language. Nonetheless, it seems to have that paradigm pegged to its creator's name. My question comes up because it doesn't seem to be widely used for multi-purpose applications. I'm not a LV-expert of any kind, I'm more like a learner. I'm still getting used to LV.

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• how to add multiview in a radio button

  - by Naveen31

  protected void ddlto_SelectedIndexChanged(object sender, EventArgs e) { } protected void RadioButton1_CheckedChanged1(object sender, EventArgs e) { MultiView1.ActiveViewIndex = 0; } protected void RadioButton2_CheckedChanged(object sender, EventArgs e) { MultiView1.ActiveViewIndex = 2; } <asp:RadioButtonList ID="RadioButtonList2" runat="server" AutoPostBack="True" RepeatDirection="Horizontal" Font-Names="Arial" Font-Size="Small" onselectedindexchanged="MultiView1_ActiveViewChanged"> <asp:ListItem Selected="True">One Way</asp:ListItem> <asp:ListItem>Round Trip</asp:ListItem> <asp:ListItem>Multi City</asp:ListItem> </asp:RadioButtonList> i have a radiolist of thre buttons-one way,round trip and multicity, i have taken a multiview in which in view 2 i have added the codes codes,and i want to show that code when i click on the 2nd radio button i.e on round trip,how to do it. plzz help

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• serial port does not exist in current context: c#

  - by I__

  here's the code: using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Threading; namespace WindowsFormsApplication1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } public class ThreadWork { private static SerialPort serialPort1; public static void DoWork() { serialPort1.Open(); serialPort1.Write("AT+CMGF=1\r\n"); //Thread.Sleep(500); serialPort1.Write("AT+CNMI=2,2\r\n"); //Thread.Sleep(500); serialPort1.Write("AT+CSCA=\"+4790002100\"\r\n"); //Thread.Sleep(500); serialPort1.DataReceived += serialPort1_DataReceived_1; } } private void Form1_Load(object sender, EventArgs e) { ThreadStart myThreadDelegate = new ThreadStart(ThreadWork.DoWork); Thread myThread = new Thread(myThreadDelegate); myThread.Start(); } private void serialPort1_DataReceived_1(object sender, System.IO.Ports.SerialDataReceivedEventArgs e) { string response = serialPort1.ReadLine(); this.BeginInvoke(new MethodInvoker(() => textBox1.AppendText(response + "\r\n"))); } } } and i get an error on this line: string response = serialPort1.ReadLine(); it says:: Error 1 The name 'serialPort1' does not exist in the current context C:\Users\alexluvsdanielle\AppData\Local\Temporary Projects\WindowsFormsApplication1\Form1.cs 44 31 WindowsFormsApplication1 what am i doing wrong?

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• What is the point/purpose of Ruby EventMachine, Python Twisted, or JavaScript Node.js?

  - by CCw

  I don't understand what problem these frameworks solve. Are they replacements for a HTTP server like Apache HTTPD, Tomcat, Mongrel, etc? Or are they more? Why might I use them... some real world examples? I've seen endless examples of chat rooms and broadcast services, but don't see how this is any different than, for instance, setting up a Java program to open sockets and dispatch a thread for each request. I think I understand the non-blocking I/O, but I don't understand how that is any different than a multi-threaded web server.

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• Fastest inline-assembly spinlock

  - by sigvardsen

  I'm writing a multithreaded application in c++, where performance is critical. I need to use a lot of locking while copying small structures between threads, for this I have chosen to use spinlocks. I have done some research and speed testing on this and I found that most implementations are roughly equally fast: Microsofts CRITICAL_SECTION, with SpinCount set to 1000, scores about 140 time units Implementing this algorithm with Microsofts InterlockedCompareExchange scores about 95 time units Ive also tried to use some inline assembly with __asm {} using something like this code and it scores about 70 time units, but I am not sure that a proper memory barrier has been created. Edit: The times given here are the time it takes for 2 threads to lock and unlock the spinlock 1,000,000 times. I know this isn't a lot of difference but as a spinlock is a heavily used object, one would think that programmers would have agreed on the fastest possible way to make a spinlock. Googling it leads to many different approaches however. I would think this aforementioned method would be the fastest if implemented using inline assembly and using the instruction CMPXCHG8B instead of comparing 32bit registers. Furthermore memory barriers must be taken into account, this could be done by LOCK CMPXHG8B (I think?), which guarantees "exclusive rights" to the shared memory between cores. At last [some suggests] that for busy waits should be accompanied by NOP:REP that would enable Hyper-threading processors to switch to another thread, but I am not sure whether this is true or not? From my performance-test of different spinlocks, it is seen that there is not much difference, but for purely academic purpose I would like to know which one is fastest. However as I have extremely limited experience in the assembly-language and with memory barriers, I would be happy if someone could write the assembly code for the last example I provided with LOCK CMPXCHG8B and proper memory barriers in the following template: __asm { spin_lock: ;locking code. spin_unlock: ;unlocking code. }

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• Double Buffering with awt

  - by DDP

  Is double buffering (in java) possible with awt? Currently, I'm aware that swing should not be used with awt, so I can't use BufferStrategy and whatnot. If double buffering is possible with awt, do I have to write the buffer by hand? Unlike swing, awt doesn't seem to have the same built-in double buffering capability. If I do have to write the code by hand, is there a good tutorial to look at? Or is it just easier/advisable for a novice programmer to use swing instead? Sorry about the multi-step question. Thanks for your time :)

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