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  • What's the best way to handle numerous recurring log entries in game loop?

    - by Kaa
    I have a custom logging system, use of which is scattered all over the engine and game. The system is linked to a "LogStore" that has an std::vector<string> logs[NUM_LOG_TYPES] - each vector corresponds with it's log type (info, error, debug, etc.). There's one extra std::vector that has "coordinates" to all log entries in the order they were received. Now, all the logging output is also displayed inside my development console in the game. The game console is handled by HTML-type GUI and therefore requires a new <p> element being added for each log output. My problem is that the log entries that are generated in the main loop each frame freeze the engine, because they continue to add elements to the in-game console, and if the console or guy generates a warning - that creates an infinite logging loop. I want to solve it by handling the recurring log entries in an elegant way that lets you know that something is critically wrong, but won't freeze the engine - like displaying the count of errors in the last 60 frames instead of displaying errors themselves. But how do you guys handle this? Does anyone know any nifty tricks to do this? I understand the question may sound vague, but if someone came across this type of issue I'm sure they would know exactly what's happening. Example problematic log entries: OpenGL warnings (I actually do check for errors every frame in many places) Really any prints anywhere in the main loop (may be debugging, may be warnings)

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  • threaded serial port IOException when writing

    - by John McDonald
    Hi, I'm trying to write a small application that simply reads data from a socket, extracts some information (two integers) from the data and sends the extracted information off on a serial port. The idea is that it should start and just keep going. In short, it works, but not for long. After a consistently short period I start to receive IOExceptions and socket receive buffer is swamped. The thread framework has been taken from the MSDN serial port example. The delay in send(), readThread.Join(), is an effort to delay read() in order to allow serial port interrupt processing a chance to occur, but I think I've misinterpreted the join function. I either need to sync the processes more effectively or throw some data away as it comes in off the socket, which would be fine. The integer data is controlling a pan tilt unit and I'm sure four times a second would be acceptable, but not sure on how to best acheive either, any ideas would be greatly appreciated, cheers. using System; using System.Collections.Generic; using System.Text; using System.IO.Ports; using System.Threading; using System.Net; using System.Net.Sockets; using System.IO; namespace ConsoleApplication1 { class Program { static bool _continue; static SerialPort _serialPort; static Thread readThread; static Thread sendThread; static String sendString; static Socket s; static int byteCount; static Byte[] bytesReceived; // synchronise send and receive threads static bool dataReceived; const int FIONREAD = 0x4004667F; static void Main(string[] args) { dataReceived = false; readThread = new Thread(Read); sendThread = new Thread(Send); bytesReceived = new Byte[16384]; // Create a new SerialPort object with default settings. _serialPort = new SerialPort("COM4", 38400, Parity.None, 8, StopBits.One); // Set the read/write timeouts _serialPort.WriteTimeout = 500; _serialPort.Open(); string moveMode = "CV "; _serialPort.WriteLine(moveMode); s = null; IPHostEntry hostEntry = Dns.GetHostEntry("localhost"); foreach (IPAddress address in hostEntry.AddressList) { IPEndPoint ipe = new IPEndPoint(address, 10001); Socket tempSocket = new Socket(ipe.AddressFamily, SocketType.Stream, ProtocolType.Tcp); tempSocket.Connect(ipe); if (tempSocket.Connected) { s = tempSocket; s.ReceiveBufferSize = 16384; break; } else { continue; } } readThread.Start(); sendThread.Start(); while (_continue) { Thread.Sleep(10); ;// Console.WriteLine("main..."); } readThread.Join(); _serialPort.Close(); s.Close(); } public static void Read() { while (_continue) { try { //Console.WriteLine("Read"); if (!dataReceived) { byte[] outValue = BitConverter.GetBytes(0); // Check how many bytes have been received. s.IOControl(FIONREAD, null, outValue); uint bytesAvailable = BitConverter.ToUInt32(outValue, 0); if (bytesAvailable > 0) { Console.WriteLine("Read thread..." + bytesAvailable); byteCount = s.Receive(bytesReceived); string str = Encoding.ASCII.GetString(bytesReceived); //str = Encoding::UTF8->GetString( bytesReceived ); string[] split = str.Split(new Char[] { '\t', '\r', '\n' }); string filteredX = (split.GetValue(7)).ToString(); string filteredY = (split.GetValue(8)).ToString(); string[] AzSplit = filteredX.Split(new Char[] { '.' }); filteredX = (AzSplit.GetValue(0)).ToString(); string[] ElSplit = filteredY.Split(new Char[] { '.' }); filteredY = (ElSplit.GetValue(0)).ToString(); // scale values int x = (int)(Convert.ToInt32(filteredX) * 1.9); string scaledAz = x.ToString(); int y = (int)(Convert.ToInt32(filteredY) * 1.9); string scaledEl = y.ToString(); String moveAz = "PS" + scaledAz + " "; String moveEl = "TS" + scaledEl + " "; sendString = moveAz + moveEl; dataReceived = true; } } } catch (TimeoutException) {Console.WriteLine("timeout exception");} catch (NullReferenceException) {Console.WriteLine("Read NULL reference exception");} } } public static void Send() { while (_continue) { try { if (dataReceived) { // sleep Read() thread to allow serial port interrupt processing readThread.Join(100); // send command to PTU dataReceived = false; Console.WriteLine(sendString); _serialPort.WriteLine(sendString); } } catch (TimeoutException) { Console.WriteLine("Timeout exception"); } catch (IOException) { Console.WriteLine("IOException exception"); } catch (NullReferenceException) { Console.WriteLine("Send NULL reference exception"); } } } } }

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  • Reworking my singly linked list

    - by Stradigos
    Hello everyone, thanks for taking the time to stop by my question. Below you will find my working SLL, but I want to make more use of C# and, instead of having two classes, SLL and Node, I want to use Node's constructors to do all the work (To where if you pass a string through the node, the constructor will chop it up into char nodes). The problem is, after an a few hours of tinkering, I'm not really getting anywhere... using System; using System.Collections.Generic; using System.Text; using System.IO; namespace PalindromeTester { class Program { static void Main(string[] args) { SLL mySLL = new SLL(); mySLL.add('a'); mySLL.add('b'); mySLL.add('c'); mySLL.add('d'); mySLL.add('e'); mySLL.add('f'); Console.Out.WriteLine("Node count = " + mySLL.count); mySLL.reverse(); mySLL.traverse(); Console.Out.WriteLine("\n The header is: " + mySLL.gethead); Console.In.ReadLine(); } class Node { private char letter; private Node next; public Node() { next = null; } public Node(char c) { this.data = c; } public Node(string s) { } public char data { get { return letter; } set { letter = value; } } public Node nextNode { get { return next; } set { next = value; } } } class SLL { private Node head; private int totalNode; public SLL() { head = null; totalNode = 0; } public void add(char s) { if (head == null) { head = new Node(); head.data = s; } else { Node temp; temp = new Node(); temp.data = s; temp.nextNode = head; head = temp; } totalNode++; } public int count { get { return totalNode; } } public char gethead { get { return head.data; } } public void traverse() { Node temp = head; while(temp != null) { Console.Write(temp.data + " "); temp = temp.nextNode; } } public void reverse() { Node q = null; Node p = this.head; while(p!=null) { Node r=p; p=p.nextNode; r.nextNode=q; q=r; } this.head = q; } } } } Here's what I have so far in trying to work it into Node's constructors: using System; using System.Collections.Generic; using System.Text; using System.IO; namespace PalindromeTester { class Program { static void Main(string[] args) { //Node myList = new Node(); //TextReader tr = new StreamReader("data.txt"); //string line; //while ((line = tr.ReadLine()) != null) //{ // Console.WriteLine(line); //} //tr.Close(); Node myNode = new Node("hello"); Console.Out.WriteLine(myNode.count); myNode.reverse(); myNode.traverse(); // Console.Out.WriteLine(myNode.gethead); Console.In.ReadLine(); } class Node { private char letter; private Node next; private Node head; private int totalNode; public Node() { head = null; totalNode = 0; } public Node(char c) { if (head == null) { head = new Node(); head.data = c; } else { Node temp; temp = new Node(); temp.data = c; temp.nextNode = head; head = temp; } totalNode++; } public Node(string s) { foreach (char x in s) { new Node(x); } } public char data { get { return letter; } set { letter = value; } } public Node nextNode { get { return next; } set { next = value; } } public void reverse() { Node q = null; Node p = this.head; while (p != null) { Node r = p; p = p.nextNode; r.nextNode = q; q = r; } this.head = q; } public void traverse() { Node temp = head; while (temp != null) { Console.Write(temp.data + " "); temp = temp.nextNode; } } public int count { get { return totalNode; } } } } } Ideally, the only constructors and methods I would be left with are Node(), Node(char c), Node(string s), Node reserve() and I'll be reworking traverse into a ToString overload. Any suggestions?

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  • System.ServiceModel.Channels.MessageHeader Error

    - by user220511
    I'm trying to get the following to work on my machine but I get an error (Cannot create an instance of the abstract class or interface 'System.ServiceModel.Channels.MessageHeader') using System; using System.IO; using System.Reflection; namespace com.mycompanyname.business { /// /// Summary description for SessionCreateRQClient. /// class SessionCreateRQClient { /// /// The main entry point. /// [STAThread] static void Main(string[] args) { try { // Set user information, including security credentials and the IPCC. string username = "user"; string password = "password"; string ipcc = "IPCC"; string domain = "DEFAULT"; string temp = Environment.GetEnvironmentVariable("tmp"); // Get temp directory string PropsFileName = temp + "/session.properties"; // Define dir and file name DateTime dt = DateTime.UtcNow; string tstamp = dt.ToString("s") + "Z"; //Create the message header and provide the conversation ID. MessageHeader msgHeader = new MessageHeader(); msgHeader.ConversationId = "TestSession"; // Set the ConversationId From from = new From(); PartyId fromPartyId = new PartyId(); PartyId[] fromPartyIdArr = new PartyId[1]; fromPartyId.Value = "WebServiceClient"; fromPartyIdArr[0] = fromPartyId; from.PartyId = fromPartyIdArr; msgHeader.From = from; To to = new To(); PartyId toPartyId = new PartyId(); PartyId[] toPartyIdArr = new PartyId[1]; toPartyId.Value = "WebServiceSupplier"; toPartyIdArr[0] = toPartyId; to.PartyId = toPartyIdArr; msgHeader.To = to; //Add the value for eb:CPAId, which is the IPCC. //Add the value for the action code of this Web service, SessionCreateRQ. msgHeader.CPAId = ipcc; msgHeader.Action = "SessionCreateRQ"; Service service = new Service(); service.Value = "SessionCreate"; msgHeader.Service = service; MessageData msgData = new MessageData(); msgData.MessageId = "mid:[email protected]"; msgData.Timestamp = tstamp; msgHeader.MessageData = msgData; Security security = new Security(); SecurityUsernameToken securityUserToken = new SecurityUsernameToken(); securityUserToken.Username = username; securityUserToken.Password = password; securityUserToken.Organization = ipcc; securityUserToken.Domain = domain; security.UsernameToken = securityUserToken; SessionCreateRQ req = new SessionCreateRQ(); SessionCreateRQPOS pos = new SessionCreateRQPOS(); SessionCreateRQPOSSource source = new SessionCreateRQPOSSource(); source.PseudoCityCode = ipcc; pos.Source = source; req.POS = pos; SessionCreateRQService serviceObj = new SessionCreateRQService(); serviceObj.MessageHeaderValue = msgHeader; serviceObj.SecurityValue = security; SessionCreateRS resp = serviceObj.SessionCreateRQ(req); // Send the request if (resp.Errors != null && resp.Errors.Error != null) { Console.WriteLine("Error : " + resp.Errors.Error.ErrorInfo.Message); } else { msgHeader = serviceObj.MessageHeaderValue; security = serviceObj.SecurityValue; Console.WriteLine("**********************************************"); Console.WriteLine("Response of SessionCreateRQ service"); Console.WriteLine("BinarySecurityToken returned : " + security.BinarySecurityToken); Console.WriteLine("**********************************************"); string ConvIdLine = "convid="+msgHeader.ConversationId; // ConversationId to a string string TokenLine = "securitytoken="+security.BinarySecurityToken; // BinarySecurityToken to a string string ipccLine = "ipcc="+ipcc; // IPCC to a string File.Delete(PropsFileName); // Clean up TextWriter tw = new StreamWriter(PropsFileName); // Create & open the file tw.WriteLine(DateTime.Now); // Write the date for reference tw.WriteLine(TokenLine); // Write the BinarySecurityToken tw.WriteLine(ConvIdLine); // Write the ConversationId tw.WriteLine(ipccLine); // Write the IPCC tw.Close(); //Console.Read(); } } catch(Exception e) { Console.WriteLine("Exception Message : " + e.Message ); Console.WriteLine("Exception Stack Trace : " + e.StackTrace); Console.Read(); } } } } I have added the reference System.ServiceModel and the lines: using System.ServiceModel; using System.ServiceModel.Channels; but I continue to get that error when trying to compile -- "Cannot create an instance of the abstract class or interface 'System.ServiceModel.Channels.MessageHeader'" I am using Microsoft Visual Studio 2008 Version 9.0.21022.8 RTM Microsoft .NET Framework Version 3.5 SP1 Professional Edition Is there another reference I have to add? Or a dll to move over? I wonder was the code above written for Framework 2.0 only? Thanks for your help.

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  • Save object states in .data or attr - Performance vs CSS?

    - by Neysor
    In response to my answer yesterday about rotating an Image, Jamund told me to use .data() instead of .attr() First I thought that he is right, but then I thought about a bigger context... Is it always better to use .data() instead of .attr()? I looked in some other posts like what-is-better-data-or-attr or jquery-data-vs-attrdata The answers were not satisfactory for me... So I moved on and edited the example by adding CSS. I thought it might be useful to make a different Style on each image if it rotates. My style was the following: .rp[data-rotate="0"] { border:10px solid #FF0000; } .rp[data-rotate="90"] { border:10px solid #00FF00; } .rp[data-rotate="180"] { border:10px solid #0000FF; } .rp[data-rotate="270"] { border:10px solid #00FF00; } Because design and coding are often separated, it could be a nice feature to handle this in CSS instead of adding this functionality into JavaScript. Also in my case the data-rotate is like a special state which the image currently has. So in my opinion it make sense to represent it within the DOM. I also thought this could be a case where it is much better to save with .attr() then with .data(). Never mentioned before in one of the posts I read. But then i thought about performance. Which function is faster? I built my own test following: <!DOCTYPE HTML> <html> <head> <title>test</title> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script> <script type="text/javascript"> function runfirst(dobj,dname){ console.log("runfirst "+dname); console.time(dname+"-attr"); for(i=0;i<10000;i++){ dobj.attr("data-test","a"+i); } console.timeEnd(dname+"-attr"); console.time(dname+"-data"); for(i=0;i<10000;i++){ dobj.data("data-test","a"+i); } console.timeEnd(dname+"-data"); } function runlast(dobj,dname){ console.log("runlast "+dname); console.time(dname+"-data"); for(i=0;i<10000;i++){ dobj.data("data-test","a"+i); } console.timeEnd(dname+"-data"); console.time(dname+"-attr"); for(i=0;i<10000;i++){ dobj.attr("data-test","a"+i); } console.timeEnd(dname+"-attr"); } $().ready(function() { runfirst($("#rp4"),"#rp4"); runfirst($("#rp3"),"#rp3"); runlast($("#rp2"),"#rp2"); runlast($("#rp1"),"#rp1"); }); </script> </head> <body> <div id="rp1">Testdiv 1</div> <div id="rp2" data-test="1">Testdiv 2</div> <div id="rp3">Testdiv 3</div> <div id="rp4" data-test="1">Testdiv 4</div> </body> </html> It should also show if there is a difference with a predefined data-test or not. One result was this: runfirst #rp4 #rp4-attr: 515ms #rp4-data: 268ms runfirst #rp3 #rp3-attr: 505ms #rp3-data: 264ms runlast #rp2 #rp2-data: 260ms #rp2-attr: 521ms runlast #rp1 #rp1-data: 284ms #rp1-attr: 525ms So the .attr() function did always need more time than the .data() function. This is an argument for .data() I thought. Because performance is always an argument! Then I wanted to post my results here with some questions, and in the act of writing I compared with the questions Stack Overflow showed me (similar titles) And true enough, there was one interesting post about performance I read it and run their example. And now I am confused! This test showed that .data() is slower then .attr() !?!! Why is that so? First I thought it is because of a different jQuery library so I edited it and saved the new one. But the result wasn't changing... So now my questions to you: Why are there some differences in the performance in these two examples? Would you prefer to use data- HTML5 attributes instead of data, if it represents a state? Although it wouldn't be needed at the time of coding? Why - Why not? Now depending on the performance: Would performance be an argument for you using .attr() instead of data, if it shows that .attr() is better? Although data is meant to be used for .data()? UPDATE 1: I did see that without overhead .data() is much faster. Misinterpreted the data :) But I'm more interested in my second question. :) Would you prefer to use data- HTML5 attributes instead of data, if it represents a state? Although it wouldn't be needed at the time of coding? Why - Why not? Are there some other reasons you can think of, to use .attr() and not .data()? e.g. interoperability? because .data() is jquery style and HTML Attributes can be read by all... UPDATE 2: As we see from T.J Crowder's speed test in his answer attr is much faster then data! which is again confusing me :) But please! Performance is an argument, but not the highest! So give answers to my other questions please too!

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  • Process.Start() and ShellExecute() fails with URLs on Windows 8

    - by Rick Strahl
    Since I installed Windows 8 I've noticed that a number of my applications appear to have problems opening URLs. That is when I click on a link inside of a Windows application, either nothing happens or there's an error that occurs. It's happening both to my own applications and a host of Windows applications I'm running. At first I thought this was an issue with my default browser (Chrome) but after switching the default browser to a few others and experimenting a bit I noticed that the errors occur - oddly enough - only when I run an application as an Administrator. I also tried switching to FireFox and Opera as my default browser and saw exactly the same behavior. The scenario for this is a bit bizarre: Running on Windows 8 Call Process.Start() (or ShellExecute() in Win32 API) with a URL or an HTML file Run 'As Administrator' (works fine under non-elevated user account!) or with UAC off A browser other than Internet Explorer is set as your Default Web Browser Talk about a weird scenario: Something that doesn't work when you run as an Administrator which is supposed to have rights to everything on the system! Instead running under an Admin account - either elevated with a User Account Control prompt or even when running as a full Administrator fails. It appears that this problem does not occur for everyone, but when I looked for a solution to this, I saw quite a few posts in relation to this with no clear resolutions. I have three Windows 8 machines running here in the office and all three of them showed this behavior. Lest you think this is just a programmer's problem - this can affect any software running on your system that needs to run under administrative rights. Try it out Now, in order for this next example to fail, any browser but Internet Explorer has to be your default browser and even then it may not fail depending on how you installed your browser. To see if this is a problem create a small Console application and call Process.Start() with a URL in it:namespace Win8ShellBugConsole { class Program { static void Main(string[] args) { Console.WriteLine("Launching Url..."); Process.Start("http://microsoft.com"); Console.Write("Press any key to continue..."); Console.ReadKey(); Console.WriteLine("\r\n\r\nLaunching image..."); Process.Start(Path.GetFullPath(@"..\..\sailbig.jpg")); Console.Write("Press any key to continue..."); Console.ReadKey(); } } } Compile this code. Then execute the code from Explorer (not from Visual Studio because that may change the permissions). If you simply run the EXE and you're not running as an administrator, you'll see the Web page pop up in the browser as well as the image loading. Now run the same thing with Run As Administrator: Now when you run it you get a nice error when Process.Start() is fired: The same happens if you are running with User Account Control off altogether - ie. you are running as a full admin account. Now if you comment out the URL in the code above and just fire the image display - that works just fine in any user mode. As does opening any other local file type or even starting a new EXE locally (ie. Process.Start("c:\windows\notepad.exe"). All that works, EXCEPT for URLs. The code above uses Process.Start() in .NET but the same happens in Win32 Applications that use the ShellExecute API. In some of my older Fox apps ShellExecute returns an error code of 31 - which is No Shell Association found. What's the Deal? It turns out the problem has to do with the way browsers are registering themselves on Windows. Internet Explorer - being a built-in application in Windows 8 - apparently does this correctly, but other browsers possibly don't or at least didn't at the time I installed them. So even Chrome, which continually updates itself, has a recent version that apparently has this registration issue fixed, I was unable to simply set IE as my default browser then use Chrome to 'Set as Default Browser'. It still didn't work. Neither did using the Set Program Associations dialog which lets you assign what extensions are mapped to by a given application. Each application provides a set of extension/moniker mappings that it supports and this dialog lets you associate them on a system wide basis. This also did not work for Chrome or any of the other browsers at first. However, after repeated retries here eventually I did manage to get FireFox to work, but not any of the others. What Works? Reinstall the Browser In the end I decided on the hard core pull the plug solution: Totally uninstall and re-install Chrome in this case. And lo and behold, after reinstall everything was working fine. Now even removing the association for Chrome, switching to IE as the default browser and then back to Chrome works. But, even though the version of Chrome I was running before uninstalling and reinstalling is the same as I'm running now after the reinstall now it works. Of course I had to find out the hard way, before Richard commented with a note regarding what the issue is with Chrome at least: http://code.google.com/p/chromium/issues/detail?id=156400 As expected the issue is a registration issue - with keys not being registered at the machine level. Reading this I'm still not sure why this should be a problem - an elevated account still runs under the same user account (ie. I'm still rickstrahl even if I Run As Administrator), so why shouldn't an app be able to read my Current User registry hive? And also that doesn't quite explain why if I register the extensions using Run As Administrator in Chrome when using Set as Default Browser). But in the end it works… Not so fast It's now a couple of days later and still there are some oddball problems although this time they appear to be purely Chrome issues. After the reinstall Chrome seems to pop up properly with ShellExecute() calls both in regular user and Admin mode. However, it now looks like Chrome is actually running two completely separate user profiles for each. For example, when I run Visual Studio in Admin mode and go to View in browser, Chrome complains that it was installed in Admin mode and can't launch (WTF?). Then you retry a few times later and it ends up working. When launched that way some of the plug-ins installed don't show up with the effect that sometimes they're visible sometimes they're not. Also Chrome seems to loose my configuration and Google sign in between sessions now, presumably when switching user modes. Add-ins installed in admin mode don't show up in user mode and vice versa. Ah, this is lovely. Did I mention that I freaking hate UAC precisely because of this kind of bullshit. You can never tell exactly what account your app is running under, and apparently apps also have a hard time trying to put data into the right place that works for both scenarios. And as my recent post on using Windows Live accounts shows it's yet another level of abstraction ontop of the underlying system identity that can cause all sort of small side effect headaches like this. Hopefully, most of you are skirting this issue altogether - having installed more recent versions of your favorite browsers. If not, hopefully this post will take you straight to reinstallation to fix this annoying issue.© Rick Strahl, West Wind Technologies, 2005-2012Posted in Windows  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Where would my different development rhythm be suitable for the work?

    - by DarenW
    Over the years I have worked on many projects, with some successful and a great benefit to the company, and some total failures with me getting fired or otherwise leaving. What is the difference? Naturally I prefer the former and wish to avoid the latter, so I'm pondering this issue. The key seems to be that my personal approach differs from the norm. I write code first, letting it be all spaghetti and chaos, using whatever tools "fit my hand" that I'm fluent in. I try to organize it, then give up and start over with a better design. I go through cycles, from thinking-design to coding-testing. This may seem to be the same as any other development process, Agile or whatever, cycling between design and coding, but there does seem to be a subtle difference: The methods (ideally) followed by most teams goes design, code; design, code; ... while I'm going code, design; code, design; (if that makes any sense.) Music analogy: some types of music have a strong downbeat while others have prominent syncopation. In practice, I just can't think in terms of UML, specifications and so on, but grok things only by attempting to code and debug and refactor ad-hoc. I need the grounding provided by coding in order to think constructively, then to offer any opinions, advice or solutions to the team and get real work done. In positions where I can initially hack up cowboy code without constraints of tool or language choices, I easily gain a "feel" for the data, requirements etc and eventually do good work. In formalized positions where paperwork and pure "design" comes first and only later any coding (even for small proof-of-concept projects), I am lost at sea and drown. Therefore, I'd like to know how to either 1) change my rhythm to match the more formalized methodology-oriented team ways of doing things, or 2) find positions at organizations where my sense of development rhythm is perfect for the work. It's probably unrealistic for a person to change their fundamental approach to things. So option 2) is preferred. So where I can I find such positions? How common is my approach and where is it seen as viable but different, and not dismissed as undisciplined or cowboy coder ways?

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  • Refactoring FizzBuzz

    - by MarkPearl
    A few years ago I blogger about FizzBuzz, at the time the post was prompted by Scott Hanselman who had podcasted about how surprized he was that some programmers could not even solve the FizzBuzz problem within a reasonable period of time during a job interview. At the time I thought I would give the problem a go in F# and sure enough the solution was fairly simple – I then also did a basic solution in C# but never posted it. Since then I have learned that being able to solve a problem and how you solve the problem are two totally different things. Today I decided to give the problem a retry and see if I had learnt anything new in the last year or so. Here is how my solution looked after refactoring… Solution 1 – Cheap and Nasty public class FizzBuzzCalculator { public string NumberFormat(int number) { var numDivisibleBy3 = (number % 3) == 0; var numDivisibleBy5 = (number % 5) == 0; if (numDivisibleBy3 && numDivisibleBy5) return String.Format("{0} FizzBuz", number); else if (numDivisibleBy3) return String.Format("{0} Fizz", number); else if (numDivisibleBy5) return String.Format("{0} Buz", number); return number.ToString(); } } class Program { static void Main(string[] args) { var fizzBuzz = new FizzBuzzCalculator(); for (int i = 0; i < 100; i++) { Console.WriteLine(fizzBuzz.NumberFormat(i)); } } } My first attempt I just looked at solving the problem – it works, and could be an acceptable solution but tonight I thought I would see how far  I could refactor it… The section I decided to focus on was the mass of if..else code in the NumberFormat method. Solution 2 – Replacing If…Else with a Dictionary public class FizzBuzzCalculator { private readonly Dictionary<Tuple<bool, bool>, string> _mappings; public FizzBuzzCalculator(Dictionary<Tuple<bool, bool>, string> mappings) { _mappings = mappings; } public string NumberFormat(int number) { var numDivisibleBy3 = (number % 3) == 0; var numDivisibleBy5 = (number % 5) == 0; var mappedKey = new Tuple<bool, bool>(numDivisibleBy3, numDivisibleBy5); return String.Format("{0} {1}", number, _mappings[mappedKey]); } } class Program { static void Main(string[] args) { var mappings = new Dictionary<Tuple<bool, bool>, string> { { new Tuple<bool, bool>(true, true), "- FizzBuzz"}, { new Tuple<bool, bool>(true, false), "- Fizz"}, { new Tuple<bool, bool>(false, true), "- Buzz"}, { new Tuple<bool, bool>(false, false), ""} }; var fizzBuzz = new FizzBuzzCalculator(mappings); for (int i = 0; i < 100; i++) { Console.WriteLine(fizzBuzz.NumberFormat(i)); } Console.ReadLine(); } } In my second attempt I looked at removing the if else in the NumberFormat method. A dictionary proved to be useful for this – I added a constructor to the class and injected the dictionary mapping. One could argue that this is totally overkill, but if I was going to use this code in a large system an approach like this makes it easy to put this data in a configuration file, which would up its OC (Open for extensibility, closed for modification principle). I could of course take the OC principle even further – the check for divisibility by 3 and 5 is tightly coupled to this class. If I wanted to make it 4 instead of 3, I would need to adjust this class. This introduces my third refactoring. Solution 3 – Introducing Delegates and Injecting them into the class public delegate bool FizzBuzzComparison(int number); public class FizzBuzzCalculator { private readonly Dictionary<Tuple<bool, bool>, string> _mappings; private readonly FizzBuzzComparison _comparison1; private readonly FizzBuzzComparison _comparison2; public FizzBuzzCalculator(Dictionary<Tuple<bool, bool>, string> mappings, FizzBuzzComparison comparison1, FizzBuzzComparison comparison2) { _mappings = mappings; _comparison1 = comparison1; _comparison2 = comparison2; } public string NumberFormat(int number) { var mappedKey = new Tuple<bool, bool>(_comparison1(number), _comparison2(number)); return String.Format("{0} {1}", number, _mappings[mappedKey]); } } class Program { private static bool DivisibleByNum(int number, int divisor) { return number % divisor == 0; } public static bool Divisibleby3(int number) { return number % 3 == 0; } public static bool Divisibleby5(int number) { return number % 5 == 0; } static void Main(string[] args) { var mappings = new Dictionary<Tuple<bool, bool>, string> { { new Tuple<bool, bool>(true, true), "- FizzBuzz"}, { new Tuple<bool, bool>(true, false), "- Fizz"}, { new Tuple<bool, bool>(false, true), "- Buzz"}, { new Tuple<bool, bool>(false, false), ""} }; var fizzBuzz = new FizzBuzzCalculator(mappings, Divisibleby3, Divisibleby5); for (int i = 0; i < 100; i++) { Console.WriteLine(fizzBuzz.NumberFormat(i)); } Console.ReadLine(); } } I have taken this one step further and introduced delegates that are injected into the FizzBuzz Calculator class, from an OC principle perspective it has probably made it more compliant than the previous Solution 2, but there seems to be a lot of noise. Anonymous Delegates increase the readability level, which is what I have done in Solution 4. Solution 4 – Anon Delegates public delegate bool FizzBuzzComparison(int number); public class FizzBuzzCalculator { private readonly Dictionary<Tuple<bool, bool>, string> _mappings; private readonly FizzBuzzComparison _comparison1; private readonly FizzBuzzComparison _comparison2; public FizzBuzzCalculator(Dictionary<Tuple<bool, bool>, string> mappings, FizzBuzzComparison comparison1, FizzBuzzComparison comparison2) { _mappings = mappings; _comparison1 = comparison1; _comparison2 = comparison2; } public string NumberFormat(int number) { var mappedKey = new Tuple<bool, bool>(_comparison1(number), _comparison2(number)); return String.Format("{0} {1}", number, _mappings[mappedKey]); } } class Program { static void Main(string[] args) { var mappings = new Dictionary<Tuple<bool, bool>, string> { { new Tuple<bool, bool>(true, true), "- FizzBuzz"}, { new Tuple<bool, bool>(true, false), "- Fizz"}, { new Tuple<bool, bool>(false, true), "- Buzz"}, { new Tuple<bool, bool>(false, false), ""} }; var fizzBuzz = new FizzBuzzCalculator(mappings, (n) => n % 3 == 0, (n) => n % 5 == 0); for (int i = 0; i < 100; i++) { Console.WriteLine(fizzBuzz.NumberFormat(i)); } Console.ReadLine(); } }   Using the anonymous delegates I think the noise level has now been reduced. This is where I am going to end this post, I have gone through 4 iterations of the code from the initial solution using If..Else to delegates and dictionaries. I think each approach would have it’s pro’s and con’s and depending on the intention of where the code would be used would be a large determining factor. If you can think of an alternative way to do FizzBuzz, add a comment!

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  • C#/.NET Little Wonders: The Concurrent Collections (1 of 3)

    - by James Michael Hare
    Once again we consider some of the lesser known classes and keywords of C#.  In the next few weeks, we will discuss the concurrent collections and how they have changed the face of concurrent programming. This week’s post will begin with a general introduction and discuss the ConcurrentStack<T> and ConcurrentQueue<T>.  Then in the following post we’ll discuss the ConcurrentDictionary<T> and ConcurrentBag<T>.  Finally, we shall close on the third post with a discussion of the BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. A brief history of collections In the beginning was the .NET 1.0 Framework.  And out of this framework emerged the System.Collections namespace, and it was good.  It contained all the basic things a growing programming language needs like the ArrayList and Hashtable collections.  The main problem, of course, with these original collections is that they held items of type object which means you had to be disciplined enough to use them correctly or you could end up with runtime errors if you got an object of a type you weren't expecting. Then came .NET 2.0 and generics and our world changed forever!  With generics the C# language finally got an equivalent of the very powerful C++ templates.  As such, the System.Collections.Generic was born and we got type-safe versions of all are favorite collections.  The List<T> succeeded the ArrayList and the Dictionary<TKey,TValue> succeeded the Hashtable and so on.  The new versions of the library were not only safer because they checked types at compile-time, in many cases they were more performant as well.  So much so that it's Microsoft's recommendation that the System.Collections original collections only be used for backwards compatibility. So we as developers came to know and love the generic collections and took them into our hearts and embraced them.  The problem is, thread safety in both the original collections and the generic collections can be problematic, for very different reasons. Now, if you are only doing single-threaded development you may not care – after all, no locking is required.  Even if you do have multiple threads, if a collection is “load-once, read-many” you don’t need to do anything to protect that container from multi-threaded access, as illustrated below: 1: public static class OrderTypeTranslator 2: { 3: // because this dictionary is loaded once before it is ever accessed, we don't need to synchronize 4: // multi-threaded read access 5: private static readonly Dictionary<string, char> _translator = new Dictionary<string, char> 6: { 7: {"New", 'N'}, 8: {"Update", 'U'}, 9: {"Cancel", 'X'} 10: }; 11:  12: // the only public interface into the dictionary is for reading, so inherently thread-safe 13: public static char? Translate(string orderType) 14: { 15: char charValue; 16: if (_translator.TryGetValue(orderType, out charValue)) 17: { 18: return charValue; 19: } 20:  21: return null; 22: } 23: } Unfortunately, most of our computer science problems cannot get by with just single-threaded applications or with multi-threading in a load-once manner.  Looking at  today's trends, it's clear to see that computers are not so much getting faster because of faster processor speeds -- we've nearly reached the limits we can push through with today's technologies -- but more because we're adding more cores to the boxes.  With this new hardware paradigm, it is even more important to use multi-threaded applications to take full advantage of parallel processing to achieve higher application speeds. So let's look at how to use collections in a thread-safe manner. Using historical collections in a concurrent fashion The early .NET collections (System.Collections) had a Synchronized() static method that could be used to wrap the early collections to make them completely thread-safe.  This paradigm was dropped in the generic collections (System.Collections.Generic) because having a synchronized wrapper resulted in atomic locks for all operations, which could prove overkill in many multithreading situations.  Thus the paradigm shifted to having the user of the collection specify their own locking, usually with an external object: 1: public class OrderAggregator 2: { 3: private static readonly Dictionary<string, List<Order>> _orders = new Dictionary<string, List<Order>>(); 4: private static readonly _orderLock = new object(); 5:  6: public void Add(string accountNumber, Order newOrder) 7: { 8: List<Order> ordersForAccount; 9:  10: // a complex operation like this should all be protected 11: lock (_orderLock) 12: { 13: if (!_orders.TryGetValue(accountNumber, out ordersForAccount)) 14: { 15: _orders.Add(accountNumber, ordersForAccount = new List<Order>()); 16: } 17:  18: ordersForAccount.Add(newOrder); 19: } 20: } 21: } Notice how we’re performing several operations on the dictionary under one lock.  With the Synchronized() static methods of the early collections, you wouldn’t be able to specify this level of locking (a more macro-level).  So in the generic collections, it was decided that if a user needed synchronization, they could implement their own locking scheme instead so that they could provide synchronization as needed. The need for better concurrent access to collections Here’s the problem: it’s relatively easy to write a collection that locks itself down completely for access, but anything more complex than that can be difficult and error-prone to write, and much less to make it perform efficiently!  For example, what if you have a Dictionary that has frequent reads but in-frequent updates?  Do you want to lock down the entire Dictionary for every access?  This would be overkill and would prevent concurrent reads.  In such cases you could use something like a ReaderWriterLockSlim which allows for multiple readers in a lock, and then once a writer grabs the lock it blocks all further readers until the writer is done (in a nutshell).  This is all very complex stuff to consider. Fortunately, this is where the Concurrent Collections come in.  The Parallel Computing Platform team at Microsoft went through great pains to determine how to make a set of concurrent collections that would have the best performance characteristics for general case multi-threaded use. Now, as in all things involving threading, you should always make sure you evaluate all your container options based on the particular usage scenario and the degree of parallelism you wish to acheive. This article should not be taken to understand that these collections are always supperior to the generic collections. Each fills a particular need for a particular situation. Understanding what each container is optimized for is key to the success of your application whether it be single-threaded or multi-threaded. General points to consider with the concurrent collections The MSDN points out that the concurrent collections all support the ICollection interface. However, since the collections are already synchronized, the IsSynchronized property always returns false, and SyncRoot always returns null.  Thus you should not attempt to use these properties for synchronization purposes. Note that since the concurrent collections also may have different operations than the traditional data structures you may be used to.  Now you may ask why they did this, but it was done out of necessity to keep operations safe and atomic.  For example, in order to do a Pop() on a stack you have to know the stack is non-empty, but between the time you check the stack’s IsEmpty property and then do the Pop() another thread may have come in and made the stack empty!  This is why some of the traditional operations have been changed to make them safe for concurrent use. In addition, some properties and methods in the concurrent collections achieve concurrency by creating a snapshot of the collection, which means that some operations that were traditionally O(1) may now be O(n) in the concurrent models.  I’ll try to point these out as we talk about each collection so you can be aware of any potential performance impacts.  Finally, all the concurrent containers are safe for enumeration even while being modified, but some of the containers support this in different ways (snapshot vs. dirty iteration).  Once again I’ll highlight how thread-safe enumeration works for each collection. ConcurrentStack<T>: The thread-safe LIFO container The ConcurrentStack<T> is the thread-safe counterpart to the System.Collections.Generic.Stack<T>, which as you may remember is your standard last-in-first-out container.  If you think of algorithms that favor stack usage (for example, depth-first searches of graphs and trees) then you can see how using a thread-safe stack would be of benefit. The ConcurrentStack<T> achieves thread-safe access by using System.Threading.Interlocked operations.  This means that the multi-threaded access to the stack requires no traditional locking and is very, very fast! For the most part, the ConcurrentStack<T> behaves like it’s Stack<T> counterpart with a few differences: Pop() was removed in favor of TryPop() Returns true if an item existed and was popped and false if empty. PushRange() and TryPopRange() were added Allows you to push multiple items and pop multiple items atomically. Count takes a snapshot of the stack and then counts the items. This means it is a O(n) operation, if you just want to check for an empty stack, call IsEmpty instead which is O(1). ToArray() and GetEnumerator() both also take snapshots. This means that iteration over a stack will give you a static view at the time of the call and will not reflect updates. Pushing on a ConcurrentStack<T> works just like you’d expect except for the aforementioned PushRange() method that was added to allow you to push a range of items concurrently. 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: // but you can also push multiple items in one atomic operation (no interleaves) 7: stack.PushRange(new [] { "Second", "Third", "Fourth" }); For looking at the top item of the stack (without removing it) the Peek() method has been removed in favor of a TryPeek().  This is because in order to do a peek the stack must be non-empty, but between the time you check for empty and the time you execute the peek the stack contents may have changed.  Thus the TryPeek() was created to be an atomic check for empty, and then peek if not empty: 1: // to look at top item of stack without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (stack.TryPeek(out item)) 5: { 6: Console.WriteLine("Top item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Stack was empty."); 11: } Finally, to remove items from the stack, we have the TryPop() for single, and TryPopRange() for multiple items.  Just like the TryPeek(), these operations replace Pop() since we need to ensure atomically that the stack is non-empty before we pop from it: 1: // to remove items, use TryPop or TryPopRange to get multiple items atomically (no interleaves) 2: if (stack.TryPop(out item)) 3: { 4: Console.WriteLine("Popped " + item); 5: } 6:  7: // TryPopRange will only pop up to the number of spaces in the array, the actual number popped is returned. 8: var poppedItems = new string[2]; 9: int numPopped = stack.TryPopRange(poppedItems); 10:  11: foreach (var theItem in poppedItems.Take(numPopped)) 12: { 13: Console.WriteLine("Popped " + theItem); 14: } Finally, note that as stated before, GetEnumerator() and ToArray() gets a snapshot of the data at the time of the call.  That means if you are enumerating the stack you will get a snapshot of the stack at the time of the call.  This is illustrated below: 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: var results = stack.GetEnumerator(); 7:  8: // but you can also push multiple items in one atomic operation (no interleaves) 9: stack.PushRange(new [] { "Second", "Third", "Fourth" }); 10:  11: while(results.MoveNext()) 12: { 13: Console.WriteLine("Stack only has: " + results.Current); 14: } The only item that will be printed out in the above code is "First" because the snapshot was taken before the other items were added. This may sound like an issue, but it’s really for safety and is more correct.  You don’t want to enumerate a stack and have half a view of the stack before an update and half a view of the stack after an update, after all.  In addition, note that this is still thread-safe, whereas iterating through a non-concurrent collection while updating it in the old collections would cause an exception. ConcurrentQueue<T>: The thread-safe FIFO container The ConcurrentQueue<T> is the thread-safe counterpart of the System.Collections.Generic.Queue<T> class.  The concurrent queue uses an underlying list of small arrays and lock-free System.Threading.Interlocked operations on the head and tail arrays.  Once again, this allows us to do thread-safe operations without the need for heavy locks! The ConcurrentQueue<T> (like the ConcurrentStack<T>) has some departures from the non-concurrent counterpart.  Most notably: Dequeue() was removed in favor of TryDequeue(). Returns true if an item existed and was dequeued and false if empty. Count does not take a snapshot It subtracts the head and tail index to get the count.  This results overall in a O(1) complexity which is quite good.  It’s still recommended, however, that for empty checks you call IsEmpty instead of comparing Count to zero. ToArray() and GetEnumerator() both take snapshots. This means that iteration over a queue will give you a static view at the time of the call and will not reflect updates. The Enqueue() method on the ConcurrentQueue<T> works much the same as the generic Queue<T>: 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5: queue.Enqueue("Second"); 6: queue.Enqueue("Third"); For front item access, the TryPeek() method must be used to attempt to see the first item if the queue.  There is no Peek() method since, as you’ll remember, we can only peek on a non-empty queue, so we must have an atomic TryPeek() that checks for empty and then returns the first item if the queue is non-empty. 1: // to look at first item in queue without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (queue.TryPeek(out item)) 5: { 6: Console.WriteLine("First item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Queue was empty."); 11: } Then, to remove items you use TryDequeue().  Once again this is for the same reason we have TryPeek() and not Peek(): 1: // to remove items, use TryDequeue. If queue is empty returns false. 2: if (queue.TryDequeue(out item)) 3: { 4: Console.WriteLine("Dequeued first item " + item); 5: } Just like the concurrent stack, the ConcurrentQueue<T> takes a snapshot when you call ToArray() or GetEnumerator() which means that subsequent updates to the queue will not be seen when you iterate over the results.  Thus once again the code below will only show the first item, since the other items were added after the snapshot. 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5:  6: var iterator = queue.GetEnumerator(); 7:  8: queue.Enqueue("Second"); 9: queue.Enqueue("Third"); 10:  11: // only shows First 12: while (iterator.MoveNext()) 13: { 14: Console.WriteLine("Dequeued item " + iterator.Current); 15: } Using collections concurrently You’ll notice in the examples above I stuck to using single-threaded examples so as to make them deterministic and the results obvious.  Of course, if we used these collections in a truly multi-threaded way the results would be less deterministic, but would still be thread-safe and with no locking on your part required! For example, say you have an order processor that takes an IEnumerable<Order> and handles each other in a multi-threaded fashion, then groups the responses together in a concurrent collection for aggregation.  This can be done easily with the TPL’s Parallel.ForEach(): 1: public static IEnumerable<OrderResult> ProcessOrders(IEnumerable<Order> orderList) 2: { 3: var proxy = new OrderProxy(); 4: var results = new ConcurrentQueue<OrderResult>(); 5:  6: // notice that we can process all these in parallel and put the results 7: // into our concurrent collection without needing any external locking! 8: Parallel.ForEach(orderList, 9: order => 10: { 11: var result = proxy.PlaceOrder(order); 12:  13: results.Enqueue(result); 14: }); 15:  16: return results; 17: } Summary Obviously, if you do not need multi-threaded safety, you don’t need to use these collections, but when you do need multi-threaded collections these are just the ticket! The plethora of features (I always think of the movie The Three Amigos when I say plethora) built into these containers and the amazing way they acheive thread-safe access in an efficient manner is wonderful to behold. Stay tuned next week where we’ll continue our discussion with the ConcurrentBag<T> and the ConcurrentDictionary<TKey,TValue>. For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here.   Tweet Technorati Tags: C#,.NET,Concurrent Collections,Collections,Multi-Threading,Little Wonders,BlackRabbitCoder,James Michael Hare

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  • AuthnRequest Settings in OIF / SP

    - by Damien Carru
    In this article, I will list the various OIF/SP settings that affect how an AuthnRequest message is created in OIF in a Federation SSO flow. The AuthnRequest message is used by an SP to start a Federation SSO operation and to indicate to the IdP how the operation should be executed: How the user should be challenged at the IdP Whether or not the user should be challenged at the IdP, even if a session already exists at the IdP for this user Which NameID format should be requested in the SAML Assertion Which binding (Artifact or HTTP-POST) should be requested from the IdP to send the Assertion Which profile should be used by OIF/SP to send the AuthnRequest message Enjoy the reading! Protocols The SAML 2.0, SAML 1.1 and OpenID 2.0 protocols define different message elements and rules that allow an administrator to influence the Federation SSO flows in different manners, when the SP triggers an SSO operation: SAML 2.0 allows extensive customization via the AuthnRequest message SAML 1.1 does not allow any customization, since the specifications do not define an authentication request message OpenID 2.0 allows for some customization, mainly via the OpenID 2.0 extensions such as PAPE or UI SAML 2.0 OIF/SP allows the customization of the SAML 2.0 AuthnRequest message for the following elements: ForceAuthn: Boolean indicating whether or not the IdP should force the user for re-authentication, even if the user has still a valid session By default set to false IsPassive Boolean indicating whether or not the IdP is allowed to interact with the user as part of the Federation SSO operation. If false, the Federation SSO operation might result in a failure with the NoPassive error code, because the IdP will not have been able to identify the user By default set to false RequestedAuthnContext Element indicating how the user should be challenged at the IdP If the SP requests a Federation Authentication Method unknown to the IdP or for which the IdP is not configured, then the Federation SSO flow will result in a failure with the NoAuthnContext error code By default missing NameIDPolicy Element indicating which NameID format the IdP should include in the SAML Assertion If the SP requests a NameID format unknown to the IdP or for which the IdP is not configured, then the Federation SSO flow will result in a failure with the InvalidNameIDPolicy error code If missing, the IdP will generally use the default NameID format configured for this SP partner at the IdP By default missing ProtocolBinding Element indicating which SAML binding should be used by the IdP to redirect the user to the SP with the SAML Assertion Set to Artifact or HTTP-POST By default set to HTTP-POST OIF/SP also allows the administrator to configure the server to: Set which binding should be used by OIF/SP to redirect the user to the IdP with the SAML 2.0 AuthnRequest message: Redirect or HTTP-POST By default set to Redirect Set which binding should be used by OIF/SP to redirect the user to the IdP during logout with SAML 2.0 Logout messages: Redirect or HTTP-POST By default set to Redirect SAML 1.1 The SAML 1.1 specifications do not define a message for the SP to send to the IdP when a Federation SSO operation is started. As such, there is no capability to configure OIF/SP on how to affect the start of the Federation SSO flow. OpenID 2.0 OpenID 2.0 defines several extensions that can be used by the SP/RP to affect how the Federation SSO operation will take place: OpenID request: mode: String indicating if the IdP/OP can visually interact with the user checkid_immediate does not allow the IdP/OP to interact with the user checkid_setup allows user interaction By default set to checkid_setup PAPE Extension: max_auth_age : Integer indicating in seconds the maximum amount of time since when the user authenticated at the IdP. If MaxAuthnAge is bigger that the time since when the user last authenticated at the IdP, then the user must be re-challenged. OIF/SP will set this attribute to 0 if the administrator configured ForceAuthn to true, otherwise this attribute won't be set Default missing preferred_auth_policies Contains a Federation Authentication Method Element indicating how the user should be challenged at the IdP By default missing Only specified in the OpenID request if the IdP/OP supports PAPE in XRDS, if OpenID discovery is used. UI Extension Popup mode Boolean indicating the popup mode is enabled for the Federation SSO By default missing Language Preference String containing the preferred language, set based on the browser's language preferences. By default missing Icon: Boolean indicating if the icon feature is enabled. In that case, the IdP/OP would look at the SP/RP XRDS to determine how to retrieve the icon By default missing Only specified in the OpenID request if the IdP/OP supports UI Extenstion in XRDS, if OpenID discovery is used. ForceAuthn and IsPassive WLST Command OIF/SP provides the WLST configureIdPAuthnRequest() command to set: ForceAuthn as a boolean: In a SAML 2.0 AuthnRequest, the ForceAuthn field will be set to true or false In an OpenID 2.0 request, if ForceAuthn in the configuration was set to true, then the max_auth_age field of the PAPE request will be set to 0, otherwise, max_auth_age won't be set IsPassive as a boolean: In a SAML 2.0 AuthnRequest, the IsPassive field will be set to true or false In an OpenID 2.0 request, if IsPassive in the configuration was set to true, then the mode field of the OpenID request will be set to checkid_immediate, otherwise set to checkid_setup Test In this test, OIF/SP is integrated with a remote SAML 2.0 IdP Partner, with the OOTB configuration. Based on this setup, when OIF/SP starts a Federation SSO flow, the following SAML 2.0 AuthnRequest would be generated: <samlp:AuthnRequest ProtocolBinding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" ID="id-E4BOT7lwbYK56lO57dBaqGUFq01WJSjAHiSR60Q4" Version="2.0" IssueInstant="2014-04-01T21:39:14Z" Destination="https://acme.com/saml20/sso">   <saml:Issuer Format="urn:oasis:names:tc:SAML:2.0:nameid-format:entity">https://sp.com/oam/fed</saml:Issuer>   <samlp:NameIDPolicy AllowCreate="true"/></samlp:AuthnRequest> Let's configure OIF/SP for that IdP Partner, so that the SP will require the IdP to re-challenge the user, even if the user is already authenticated: Enter the WLST environment by executing:$IAM_ORACLE_HOME/common/bin/wlst.sh Connect to the WLS Admin server:connect() Navigate to the Domain Runtime branch:domainRuntime() Execute the configureIdPAuthnRequest() command:configureIdPAuthnRequest(partner="AcmeIdP", forceAuthn="true") Exit the WLST environment:exit() After the changes, the following SAML 2.0 AuthnRequest would be generated: <samlp:AuthnRequest ForceAuthn="true" ProtocolBinding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" ID="id-E4BOT7lwbYK56lO57dBaqGUFq01WJSjAHiSR60Q4" Version="2.0" IssueInstant="2014-04-01T21:39:14Z" Destination="https://acme.com/saml20/sso">   <saml:Issuer Format="urn:oasis:names:tc:SAML:2.0:nameid-format:entity">https://sp.com/oam/fed</saml:Issuer>   <samlp:NameIDPolicy AllowCreate="true"/></samlp:AuthnRequest> To display or delete the ForceAuthn/IsPassive settings, perform the following operatons: Enter the WLST environment by executing:$IAM_ORACLE_HOME/common/bin/wlst.sh Connect to the WLS Admin server:connect() Navigate to the Domain Runtime branch:domainRuntime() Execute the configureIdPAuthnRequest() command: To display the ForceAuthn/IsPassive settings on the partnerconfigureIdPAuthnRequest(partner="AcmeIdP", displayOnly="true") To delete the ForceAuthn/IsPassive settings from the partnerconfigureIdPAuthnRequest(partner="AcmeIdP", delete="true") Exit the WLST environment:exit() Requested Fed Authn Method In my earlier "Fed Authentication Method Requests in OIF / SP" article, I discussed how OIF/SP could be configured to request a specific Federation Authentication Method from the IdP when starting a Federation SSO operation, by setting elements in the SSO request message. WLST Command The OIF WLST commands that can be used are: setIdPPartnerProfileRequestAuthnMethod() which will configure the requested Federation Authentication Method in a specific IdP Partner Profile, and accepts the following parameters: partnerProfile: name of the IdP Partner Profile authnMethod: the Federation Authentication Method to request displayOnly: an optional parameter indicating if the method should display the current requested Federation Authentication Method instead of setting it delete: an optional parameter indicating if the method should delete the current requested Federation Authentication Method instead of setting it setIdPPartnerRequestAuthnMethod() which will configure the specified IdP Partner entry with the requested Federation Authentication Method, and accepts the following parameters: partner: name of the IdP Partner authnMethod: the Federation Authentication Method to request displayOnly: an optional parameter indicating if the method should display the current requested Federation Authentication Method instead of setting it delete: an optional parameter indicating if the method should delete the current requested Federation Authentication Method instead of setting it This applies to SAML 2.0 and OpenID 2.0 protocols. See the "Fed Authentication Method Requests in OIF / SP" article for more information. Test In this test, OIF/SP is integrated with a remote SAML 2.0 IdP Partner, with the OOTB configuration. Based on this setup, when OIF/SP starts a Federation SSO flow, the following SAML 2.0 AuthnRequest would be generated: <samlp:AuthnRequest ProtocolBinding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" ID="id-E4BOT7lwbYK56lO57dBaqGUFq01WJSjAHiSR60Q4" Version="2.0" IssueInstant="2014-04-01T21:39:14Z" Destination="https://acme.com/saml20/sso">   <saml:Issuer Format="urn:oasis:names:tc:SAML:2.0:nameid-format:entity">https://sp.com/oam/fed</saml:Issuer>   <samlp:NameIDPolicy AllowCreate="true"/></samlp:AuthnRequest> Let's configure OIF/SP for that IdP Partner, so that the SP will request the IdP to use a mechanism mapped to the urn:oasis:names:tc:SAML:2.0:ac:classes:X509 Federation Authentication Method to authenticate the user: Enter the WLST environment by executing:$IAM_ORACLE_HOME/common/bin/wlst.sh Connect to the WLS Admin server:connect() Navigate to the Domain Runtime branch:domainRuntime() Execute the setIdPPartnerRequestAuthnMethod() command:setIdPPartnerRequestAuthnMethod("AcmeIdP", "urn:oasis:names:tc:SAML:2.0:ac:classes:X509") Exit the WLST environment:exit() After the changes, the following SAML 2.0 AuthnRequest would be generated: <samlp:AuthnRequest ProtocolBinding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" ID="id-E4BOT7lwbYK56lO57dBaqGUFq01WJSjAHiSR60Q4" Version="2.0" IssueInstant="2014-04-01T21:39:14Z" Destination="https://acme.com/saml20/sso">   <saml:Issuer Format="urn:oasis:names:tc:SAML:2.0:nameid-format:entity">https://sp.com/oam/fed</saml:Issuer>   <samlp:NameIDPolicy AllowCreate="true"/>   <samlp:RequestedAuthnContext Comparison="minimum">      <saml:AuthnContextClassRef xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">         urn:oasis:names:tc:SAML:2.0:ac:classes:X509      </saml:AuthnContextClassRef>   </samlp:RequestedAuthnContext></samlp:AuthnRequest> NameID Format The SAML 2.0 protocol allows for the SP to request from the IdP a specific NameID format to be used when the Assertion is issued by the IdP. Note: SAML 1.1 and OpenID 2.0 do not provide such a mechanism Configuring OIF The administrator can configure OIF/SP to request a NameID format in the SAML 2.0 AuthnRequest via: The OAM Administration Console, in the IdP Partner entry The OIF WLST setIdPPartnerNameIDFormat() command that will modify the IdP Partner configuration OAM Administration Console To configure the requested NameID format via the OAM Administration Console, perform the following steps: Go to the OAM Administration Console: http(s)://oam-admin-host:oam-admin-port/oamconsole Navigate to Identity Federation -> Service Provider Administration Open the IdP Partner you wish to modify In the Authentication Request NameID Format dropdown box with one of the values None The NameID format will be set Default Email Address The NameID format will be set urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress X.509 Subject The NameID format will be set urn:oasis:names:tc:SAML:1.1:nameid-format:X509SubjectName Windows Name Qualifier The NameID format will be set urn:oasis:names:tc:SAML:1.1:nameid-format:WindowsDomainQualifiedName Kerberos The NameID format will be set urn:oasis:names:tc:SAML:2.0:nameid-format:kerberos Transient The NameID format will be set urn:oasis:names:tc:SAML:2.0:nameid-format:transient Unspecified The NameID format will be set urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified Custom In this case, a field would appear allowing the administrator to indicate the custom NameID format to use The NameID format will be set to the specified format Persistent The NameID format will be set urn:oasis:names:tc:SAML:2.0:nameid-format:persistent I selected Email Address in this example Save WLST Command To configure the requested NameID format via the OIF WLST setIdPPartnerNameIDFormat() command, perform the following steps: Enter the WLST environment by executing:$IAM_ORACLE_HOME/common/bin/wlst.sh Connect to the WLS Admin server:connect() Navigate to the Domain Runtime branch:domainRuntime() Execute the setIdPPartnerNameIDFormat() command:setIdPPartnerNameIDFormat("PARTNER", "FORMAT", customFormat="CUSTOM") Replace PARTNER with the IdP Partner name Replace FORMAT with one of the following: orafed-none The NameID format will be set Default orafed-emailaddress The NameID format will be set urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress orafed-x509 The NameID format will be set urn:oasis:names:tc:SAML:1.1:nameid-format:X509SubjectName orafed-windowsnamequalifier The NameID format will be set urn:oasis:names:tc:SAML:1.1:nameid-format:WindowsDomainQualifiedName orafed-kerberos The NameID format will be set urn:oasis:names:tc:SAML:2.0:nameid-format:kerberos orafed-transient The NameID format will be set urn:oasis:names:tc:SAML:2.0:nameid-format:transient orafed-unspecified The NameID format will be set urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified orafed-custom In this case, a field would appear allowing the administrator to indicate the custom NameID format to use The NameID format will be set to the specified format orafed-persistent The NameID format will be set urn:oasis:names:tc:SAML:2.0:nameid-format:persistent customFormat will need to be set if the FORMAT is set to orafed-custom An example would be:setIdPPartnerNameIDFormat("AcmeIdP", "orafed-emailaddress") Exit the WLST environment:exit() Test In this test, OIF/SP is integrated with a remote SAML 2.0 IdP Partner, with the OOTB configuration. Based on this setup, when OIF/SP starts a Federation SSO flow, the following SAML 2.0 AuthnRequest would be generated: <samlp:AuthnRequest ProtocolBinding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" ID="id-E4BOT7lwbYK56lO57dBaqGUFq01WJSjAHiSR60Q4" Version="2.0" IssueInstant="2014-04-01T21:39:14Z" Destination="https://acme.com/saml20/sso">   <saml:Issuer Format="urn:oasis:names:tc:SAML:2.0:nameid-format:entity">https://sp.com/oam/fed</saml:Issuer> <samlp:NameIDPolicy AllowCreate="true"/></samlp:AuthnRequest> After the changes performed either via the OAM Administration Console or via the OIF WLST setIdPPartnerNameIDFormat() command where Email Address would be requested as the NameID Format, the following SAML 2.0 AuthnRequest would be generated: <samlp:AuthnRequest ForceAuthn="false" IsPassive="false" ProtocolBinding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" ID="id-E4BOT7lwbYK56lO57dBaqGUFq01WJSjAHiSR60Q4" Version="2.0" IssueInstant="2014-04-01T21:39:14Z" Destination="https://acme.com/saml20/sso">   <saml:Issuer Format="urn:oasis:names:tc:SAML:2.0:nameid-format:entity">https://sp.com/oam/fed</saml:Issuer> <samlp:NameIDPolicy Format="urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress" AllowCreate="true"/></samlp:AuthnRequest> Protocol Binding The SAML 2.0 specifications define a way for the SP to request which binding should be used by the IdP to redirect the user to the SP with the SAML 2.0 Assertion: the ProtocolBinding attribute indicates the binding the IdP should use. It is set to: Either urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST for HTTP-POST Or urn:oasis:names:tc:SAML:2.0:bindings:Artifact for Artifact The SAML 2.0 specifications also define different ways to redirect the user from the SP to the IdP with the SAML 2.0 AuthnRequest message, as the SP can send the message: Either via HTTP Redirect Or HTTP POST (Other bindings can theoretically be used such as Artifact, but these are not used in practice) Configuring OIF OIF can be configured: Via the OAM Administration Console or the OIF WLST configureSAMLBinding() command to set the Assertion Response binding to be used Via the OIF WLST configureSAMLBinding() command to indicate how the SAML AuthnRequest message should be sent Note: the binding for sending the SAML 2.0 AuthnRequest message will also be used to send the SAML 2.0 LogoutRequest and LogoutResponse messages. OAM Administration Console To configure the SSO Response/Assertion Binding via the OAM Administration Console, perform the following steps: Go to the OAM Administration Console: http(s)://oam-admin-host:oam-admin-port/oamconsole Navigate to Identity Federation -> Service Provider Administration Open the IdP Partner you wish to modify Check the "HTTP POST SSO Response Binding" box to request the IdP to return the SSO Response via HTTP POST, otherwise uncheck it to request artifact Save WLST Command To configure the SSO Response/Assertion Binding as well as the AuthnRequest Binding via the OIF WLST configureSAMLBinding() command, perform the following steps: Enter the WLST environment by executing:$IAM_ORACLE_HOME/common/bin/wlst.sh Connect to the WLS Admin server:connect() Navigate to the Domain Runtime branch:domainRuntime() Execute the configureSAMLBinding() command:configureSAMLBinding("PARTNER", "PARTNER_TYPE", binding, ssoResponseBinding="httppost") Replace PARTNER with the Partner name Replace PARTNER_TYPE with the Partner type (idp or sp) Replace binding with the binding to be used to send the AuthnRequest and LogoutRequest/LogoutResponse messages (should be httpredirect in most case; default) httppost for HTTP-POST binding httpredirect for HTTP-Redirect binding Specify optionally ssoResponseBinding to indicate how the SSO Assertion should be sent back httppost for HTTP-POST binding artifactfor for Artifact binding An example would be:configureSAMLBinding("AcmeIdP", "idp", "httpredirect", ssoResponseBinding="httppost") Exit the WLST environment:exit() Test In this test, OIF/SP is integrated with a remote SAML 2.0 IdP Partner, with the OOTB configuration which requests HTTP-POST from the IdP to send the SSO Assertion. Based on this setup, when OIF/SP starts a Federation SSO flow, the following SAML 2.0 AuthnRequest would be generated: <samlp:AuthnRequest ProtocolBinding="urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST" ID="id-E4BOT7lwbYK56lO57dBaqGUFq01WJSjAHiSR60Q4" Version="2.0" IssueInstant="2014-04-01T21:39:14Z" Destination="https://acme.com/saml20/sso">   <saml:Issuer Format="urn:oasis:names:tc:SAML:2.0:nameid-format:entity">https://sp.com/oam/fed</saml:Issuer>   <samlp:NameIDPolicy AllowCreate="true"/></samlp:AuthnRequest> In the next article, I will cover the various crypto configuration properties in OIF that are used to affect the Federation SSO exchanges.Cheers,Damien Carru

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  • If I define a property to prototype appears in the constructor of object, why?

    - by Eduard Florinescu
    I took the example from this question modified a bit: What is the point of the prototype method? function employee(name,jobtitle,born) { this.name=name; this.jobtitle=jobtitle; this.born=born; this.status="single" } employee.prototype.salary=10000000; var fred=new employee("Fred Flintstone","Caveman",1970); console.log(fred.salary); fred.salary=20000; console.log(fred.salary) And the output in console is this: What is the difference salary is in constructor but I still can access it with fred.salary, how can I see if is in constructor from code, status is still employee property how can I tell for example if name is the one of employee or has been touch by initialization? Why is salary in constructor, when name,jobtitle,born where "touched" by employee("Fred Flintstone","Caveman",1970); «constructor»?

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  • Using Delegates in C# (Part 1)

    - by rajbk
    This post provides a very basic introduction of delegates in C#. Part 2 of this post can be read here. A delegate is a class that is derived from System.Delegate.  It contains a list of one or more methods called an invocation list. When a delegate instance is “invoked” with the arguments as defined in the signature of the delegate, each of the methods in the invocation list gets invoked with the arguments. The code below shows example with static and instance methods respectively: Static Methods 1: using System; 2: using System.Linq; 3: using System.Collections.Generic; 4: 5: public delegate void SayName(string name); 6: 7: public class Program 8: { 9: [STAThread] 10: static void Main(string[] args) 11: { 12: SayName englishDelegate = new SayName(SayNameInEnglish); 13: SayName frenchDelegate = new SayName(SayNameInFrench); 14: SayName combinedDelegate =(SayName)Delegate.Combine(englishDelegate, frenchDelegate); 15: 16: combinedDelegate.Invoke("Tom"); 17: Console.ReadLine(); 18: } 19: 20: static void SayNameInFrench(string name) { 21: Console.WriteLine("J'ai m'appelle " + name); 22: } 23: 24: static void SayNameInEnglish(string name) { 25: Console.WriteLine("My name is " + name); 26: } 27: } We have declared a delegate of type SayName with return type of void and taking an input parameter of name of type string. On line 12, we create a new instance of this delegate which refers to a static method - SayNameInEnglish.  SayNameInEnglish has the same return type and parameter list as the delegate declaration.  Once a delegate is instantiated, the instance will always refer to the same target. Delegates are immutable. On line 13, we create a new instance of the delegate but point to a different static method. As you may recall, a delegate instance encapsulates an invocation list. You create an invocation list by combining delegates using the Delegate.Combine method (there is an easier syntax as you will see later). When two non null delegate instances are combined, their invocation lists get combined to form a new invocation list. This is done in line 14.  On line 16, we invoke the delegate with the Invoke method and pass in the required string parameter. Since the delegate has an invocation list with two entries, each of the method in the invocation list is invoked. If an unhandled exception occurs during the invocation of one of these methods, the exception gets bubbled up to the line where the invocation was made (line 16). If a delegate is null and you try to invoke it, you will get a System.NullReferenceException. We see the following output when the method is run: My name is TomJ'ai m'apelle Tom Instance Methods The code below outputs the same results as before. The only difference here is we are creating delegates that point to a target object (an instance of Translator) and instance methods which have the same signature as the delegate type. The target object can never be null. We also use the short cut syntax += to combine the delegates instead of Delegate.Combine. 1: public delegate void SayName(string name); 2: 3: public class Program 4: { 5: [STAThread] 6: static void Main(string[] args) 7: { 8: Translator translator = new Translator(); 9: SayName combinedDelegate = new SayName(translator.SayNameInEnglish); 10: combinedDelegate += new SayName(translator.SayNameInFrench); 11:  12: combinedDelegate.Invoke("Tom"); 13: Console.ReadLine(); 14: } 15: } 16: 17: public class Translator { 18: public void SayNameInFrench(string name) { 19: Console.WriteLine("J'ai m'appelle " + name); 20: } 21: 22: public void SayNameInEnglish(string name) { 23: Console.WriteLine("My name is " + name); 24: } 25: } A delegate can be removed from a combination of delegates by using the –= operator. Removing a delegate from an empty list or removing a delegate that does not exist in a non empty list will not result in an exception. Delegates are invoked synchronously using the Invoke method. We can also invoke them asynchronously using the BeginInvoke and EndInvoke methods which are compiler generated.

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  • Example: Controlling randomizer using code contracts

    - by DigiMortal
    One cool addition to Visual Studio 2010 is support for code contracts. Code contracts make sure that all conditions under what method is supposed to run correctly are met. Those who are familiar with unit tests will find code contracts easy to use. In this posting I will show you simple example about static contract checking (example solution is included). To try out code contracts you need at least Visual Studio 2010 Standard Edition. Also you need code contracts package. You can download package from DevLabs Code Contracts page. NB! Speakers, you can use the example solution in your presentations as long as you mention me and this blog in your sessions. Solution has readme.txt file that gives you steps to go through when presenting solution in sessions. This blog posting is companion posting for Visual Studio solution referred below. As an example let’s look at the following class. public class Randomizer {     public static int GetRandomFromRange(int min, int max)     {         var rnd = new Random();         return rnd.Next(min, max);     }       public static int GetRandomFromRangeContracted(int min, int max)     {         Contract.Requires(min < max, "Min must be less than max");           var rnd = new Random();         return rnd.Next(min, max);     } } GetRandomFromRange() method returns results without any checking. GetRandomFromRangeContracted() uses one code contract that makes sure that minimum value is less than maximum value. Now let’s run the following code. class Program {     static void Main(string[] args)     {         var random1 = Randomizer.GetRandomFromRange(0, 9);         Console.WriteLine("Random 1: " + random1);           var random2 = Randomizer.GetRandomFromRange(1, 1);         Console.WriteLine("Random 2: " + random2);           var random3 = Randomizer.GetRandomFromRangeContracted(5, 5);         Console.WriteLine("Random 3: " + random3);           Console.WriteLine(" ");         Console.WriteLine("Press any key to exit ...");         Console.ReadKey();     } } As we have not turned on support for code contracts the code runs without any problems and we get no warnings by Visual Studio that something is wrong. Now let’s turn on static checking for code contracts. As you can see then code still compiles without any errors but Visual Studio warns you about possible problems with contracts. Click on image to see it at original size.  When we open Error list and run our application we get the following output to errors list. Note that these messages are not shown immediately. There is little delay between application starting and appearance of these messages. So wait couple of seconds before going out of your mind. Click on image to see it at original size.  If you look at these warnings you can see that warnings show you illegal calls and also contracts against what they are going. Third warning points to GetRandomFromRange() method and shows that there should be also problem that can be detected by contract. Download Code Contracts example VS2010 solution | 30KB

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  • A Basic Thread

    - by Joe Mayo
    Most of the programs written are single-threaded, meaning that they run on the main execution thread. For various reasons such as performance, scalability, and/or responsiveness additional threads can be useful. .NET has extensive threading support, from the basic threads introduced in v1.0 to the Task Parallel Library (TPL) introduced in v4.0. To get started with threads, it's helpful to begin with the basics; starting a Thread. Why Do I Care? The scenario I'll use for needing to use a thread is writing to a file.  Sometimes, writing to a file takes a while and you don't want your user interface to lock up until the file write is done. In other words, you want the application to be responsive to the user. How Would I Go About It? The solution is to launch a new thread that performs the file write, allowing the main thread to return to the user right away.  Whenever the file writing thread completes, it will let the user know.  In the meantime, the user is free to interact with the program for other tasks. The following examples demonstrate how to do this. Show Me the Code? The code we'll use to work with threads is in the System.Threading namespace, so you'll need the following using directive at the top of the file: using System.Threading; When you run code on a thread, the code is specified via a method.  Here's the code that will execute on the thread: private static void WriteFile() { Thread.Sleep(1000); Console.WriteLine("File Written."); } The call to Thread.Sleep(1000) delays thread execution. The parameter is specified in milliseconds, and 1000 means that this will cause the program to sleep for approximately 1 second.  This method happens to be static, but that's just part of this example, which you'll see is launched from the static Main method.  A thread could be instance or static.  Notice that the method does not have parameters and does not have a return type. As you know, the way to refer to a method is via a delegate.  There is a delegate named ThreadStart in System.Threading that refers to a method without parameters or return type, shown below: ThreadStart fileWriterHandlerDelegate = new ThreadStart(WriteFile); I'll show you the whole program below, but the ThreadStart instance above goes in the Main method. The thread uses the ThreadStart instance, fileWriterHandlerDelegate, to specify the method to execute on the thread: Thread fileWriter = new Thread(fileWriterHandlerDelegate); As shown above, the argument type for the Thread constructor is the ThreadStart delegate type. The fileWriterHandlerDelegate argument is an instance of the ThreadStart delegate type. This creates an instance of a thread and what code will execute, but the new thread instance, fileWriter, isn't running yet. You have to explicitly start it, like this: fileWriter.Start(); Now, the code in the WriteFile method is executing on a separate thread. Meanwhile, the main thread that started the fileWriter thread continues on it's own.  You have two threads running at the same time. Okay, I'm Starting to Get Glassy Eyed. How Does it All Fit Together? The example below is the whole program, pulling all the previous bits together. It's followed by its output and an explanation. using System; using System.Threading; namespace BasicThread { class Program { static void Main() { ThreadStart fileWriterHandlerDelegate = new ThreadStart(WriteFile); Thread fileWriter = new Thread(fileWriterHandlerDelegate); Console.WriteLine("Starting FileWriter"); fileWriter.Start(); Console.WriteLine("Called FileWriter"); Console.ReadKey(); } private static void WriteFile() { Thread.Sleep(1000); Console.WriteLine("File Written"); } } } And here's the output: Starting FileWriter Called FileWriter File Written So, Why are the Printouts Backwards? The output above corresponds to Console.Writeline statements in the program, with the second and third seemingly reversed. In a single-threaded program, "File Written" would print before "Called FileWriter". However, this is a multi-threaded (2 or more threads) program.  In multi-threading, you can't make any assumptions about when a given thread will run.  In this case, I added the Sleep statement to the WriteFile method to greatly increase the chances that the message from the main thread will print first. Without the Thread.Sleep, you could run this on a system with multiple cores and/or multiple processors and potentially get different results each time. Interesting Tangent but What Should I Get Out of All This? Going back to the main point, launching the WriteFile method on a separate thread made the program more responsive.  The file writing logic ran for a while, but the main thread returned to the user, as demonstrated by the print out of "Called FileWriter".  When the file write finished, it let the user know via another print statement. This was a very efficient use of CPU resources that made for a more pleasant user experience. Joe

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  • Thread.Interrupt Is Evil

    - by Alois Kraus
    Recently I have found an interesting issue with Thread.Interrupt during application shutdown. Some application was crashing once a week and we had not really a clue what was the issue. Since it happened not very often it was left as is until we have got some memory dumps during the crash. A memory dump usually means WindDbg which I really like to use (I know I am one of the very few fans of it).  After a quick analysis I did find that the main thread already had exited and the thread with the crash was stuck in a Monitor.Wait. Strange Indeed. Running the application a few thousand times under the debugger would potentially not have shown me what the reason was so I decided to what I call constructive debugging. I did create a simple Console application project and try to simulate the exact circumstances when the crash did happen from the information I have via memory dump and source code reading. The thread that was  crashing was actually MS code from an old version of the Microsoft Caching Application Block. From reading the code I could conclude that the main thread did call the Dispose method on the CacheManger class which did call Thread.Interrupt on the cache scavenger thread which was just waiting for work to do. My first version of the repro looked like this   static void Main(string[] args) { Thread t = new Thread(ThreadFunc) { IsBackground = true, Name = "Test Thread" }; t.Start(); Console.WriteLine("Interrupt Thread"); t.Interrupt(); } static void ThreadFunc() { while (true) { object value = Dequeue(); // block until unblocked or awaken via ThreadInterruptedException } } static object WaitObject = new object(); static object Dequeue() { object lret = "got value"; try { lock (WaitObject) { } } catch (ThreadInterruptedException) { Console.WriteLine("Got ThreadInterruptException"); lret = null; } return lret; } I do start a background thread and call Thread.Interrupt on it and then directly let the application terminate. The thread in the meantime does plenty of Monitor.Enter/Leave calls to simulate work on it. This first version did not crash. So I need to dig deeper. From the memory dump I did know that the finalizer thread was doing just some critical finalizers which were closing file handles. Ok lets add some long running finalizers to the sample. class FinalizableObject : CriticalFinalizerObject { ~FinalizableObject() { Console.WriteLine("Hi we are waiting to finalize now and block the finalizer thread for 5s."); Thread.Sleep(5000); } } class Program { static void Main(string[] args) { FinalizableObject fin = new FinalizableObject(); Thread t = new Thread(ThreadFunc) { IsBackground = true, Name = "Test Thread" }; t.Start(); Console.WriteLine("Interrupt Thread"); t.Interrupt(); GC.KeepAlive(fin); // prevent finalizing it too early // After leaving main the other thread is woken up via Thread.Abort // while we are finalizing. This causes a stackoverflow in the CLR ThreadAbortException handling at this time. } With this changed Main method and a blocking critical finalizer I did get my crash just like the real application. The funny thing is that this is actually a CLR bug. When the main method is left the CLR does suspend all threads except the finalizer thread and declares all objects as garbage. After the normal finalizers were called the critical finalizers are executed to e.g. free OS handles (usually). Remember that I did call Thread.Interrupt as one of the last methods in the Main method. The Interrupt method is actually asynchronous and does wake a thread up and throws a ThreadInterruptedException only once unlike Thread.Abort which does rethrow the exception when an exception handling clause is left. It seems that the CLR does not expect that a frozen thread does wake up again while the critical finalizers are executed. While trying to raise a ThreadInterrupedException the CLR goes down with an stack overflow. Ups not so nice. Why has this nobody noticed for years is my next question. As it turned out this error does only happen on the CLR for .NET 4.0 (x86 and x64). It does not show up in earlier or later versions of the CLR. I have reported this issue on connect here but so far it was not confirmed as a CLR bug. But I would be surprised if my console application was to blame for a stack overflow in my test thread in a Monitor.Wait call. What is the moral of this story? Thread.Abort is evil but Thread.Interrupt is too. It is so evil that even the CLR of .NET 4.0 contains a race condition during the CLR shutdown. When the CLR gurus can get it wrong the chances are high that you get it wrong too when you use this constructs. If you do not believe me see what Patrick Smacchia does blog about Thread.Abort and List.Sort. Not only the CLR creators can get it wrong. The BCL writers do sometimes have a hard time with correct exception handling as well. If you do tell me that you use Thread.Abort frequently and never had problems with it I do suspect that you do not have looked deep enough into your application to find such sporadic errors.

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  • Java update alert: issue with EAS 11.1.2.3

    - by inowodwo
    (in via Nancy) Customers using EPM 11.1.2.3 and a web browser to launch the Essbase Administration Services Console will lose the ability to launch EAS Console via the Web URL if they apply Java 1.7 build 45. Development is currently investigating this issue. Workaround: If Java 1.7 Update 45 has been installed, it will need to be uninstalled and a previous version will need to be installed. Older versions of Java are available in the Java Archive Note: Though it may work, Java 1.7 is not supported in previous versions of EAS. Customers running a version of EAS Console prior to 11.1.2.3 need to install the supported version of JRE. Follow this in the Community

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  • How to use PAM to restrict HTTP access for some users?

    - by MaxB
    I've read that PAM can be used to restrict HTTP access for some users, but I can't figure out how to do it in Ubuntu 12.04. The /etc/security/time.conf man page contains this example: All users except for root are denied access to console-login at all times: login ; tty* & !ttyp* ; !root ; !Al0000-2400 For this to work, /etc/pam.d/login needs to have a line account requisite pam_time.so This example works, and I tried to adapt it to limit HTTP access from the console. I added http ; tty* & !ttyp* ; !root ; !Al0000-2400 to /etc/security/time.conf, and created /etc/pam.d/http with account requisite pam_time.so This doesn't work. I can still use wget as non-root from the console.

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  • My ubuntu with unity not loading after last reboot

    - by Abonec
    I have asus u36sd and after last reboot I can't start up my ubuntu 11.10. Usually I suspend my notebook by closing cover but today I reboot it and it not starting up. Booting flowing by normal till to login screen but if I move mouse cursor after that image immediately switch to console (without any error; only normal loading startup processes) and back to login screen. I can type my password and boot continuing loading but after few moment it again switch back to dark console and switch again to login screen. I can load recovery mode but if I try touch my cursor (by mouse or internal notebook touchpad) it again switch back to console and to login screen. But if I use only keyboard it work fine. Where I can see detailed log information about my problem?

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  • does class reference itself static anti pattern in prism

    - by Michael Riva
    I have an application and my desing approach look like this: class Manager { public int State; static Manager _instance = null; public static Manager Instance { get { return _instance; } set { if (_instance == value) return; _instance = value; } } public Manager() { State = 0; Instance=this; } } class Module1 { public void GetState() { Console.WriteLine(Manager.Instance.State); } } class Module2 { public void GetState() { Console.WriteLine(Manager.Instance.State); } } class Module3 { public void GetState() { Console.WriteLine(Manager.Instance.State); } } Manager class already registered in Bootstrapper like : protected override void ConfigureContainer() { base.ConfigureContainer(); Container.RegisterType<Manager>(new ContainerControlledLifetimeManager()); } protected override void InitializeModules() { Manager man= Container.Resolve<Manager>(); } Question is do I need to define my manager object as static in its field to be able to reach its state? Or this is anti pattern or bad for performance?

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  • C# : Parsing information out of a path

    - by mbcrump
    If you have a path for example: \\MyServer\MyFolderA\MyFolderB\MyFile.jpg and you need to parse out the filename, directory name or the directory parent name. You should use the fileinfo class instead of a regex expression or a string split. See the example code below:   Code Snippet using System; using System.IO;   class Test {     static void Main(string[] args)     {         string file = @"\\MyServer\MyFolderA\MyFolderB\MyFile.jpg";         FileInfo fi = new FileInfo(file);         Console.WriteLine(fi.Name);                  // Prints File.jpg         Console.WriteLine(fi.Directory.Name);        // Prints FolderB         Console.WriteLine(fi.Directory.Parent.Name); // Prints FolderA     } }

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  • How to get output from upstart jobs when logged in via SSH?

    - by Binarus
    Hi, at the moment, I am trying to learn upstart and can't get around a basic problem. To monitor what my job definitions are doing, I would like to see text output from the jobs. That does not seem to be possible when I am logged on via SSH. Currently, I am having this problem with Natty 11.04, but I am convinced that it is a more common one. Probably I just don't know about some important, yet very basic, fact. A simple job file I use (filename /etc/init/test.conf): description "test" start on test console owner kill timeout 5 task script /bin/echo Gotcha... end script My goal is to see the text "Gotcha..." when doing "initctl emit test" or "initctl start test". But that does not work. What I have tried so far: "console output" instead of "console owner" "exec /bin/echo Gotcha..." instead of script...end script I am grateful for any advice. Thank you very much, Binarus

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  • Is JScript dying? If so, where should I go? [closed]

    - by David Is Not Here
    I recently poked around Google for a little bit, looking for information about coding JScript. It's very sparse, which surprised me -- it took a link to a link to find Microsoft's own reference, which appears to omit most if not all references to console-based scripting that extends past Javascript. I'm working with the console here, not a webpage, so input and output seems very different than what Microsoft explains. If JScript is dying (and it appears to be so), where do I go from here? VBScript? My options are limited because the computers I'm using this on are carefully patrolled for new software. JScript's similarity to JavaScript was the biggest reason I had chosen it for porting over some of my prior work. I'm specifically looking for, at best, a console scripting language that doesn't need any extra software on Windows XP or higher, that at least supports standard input, output, pause, and file manipulation, little else.

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  • Given an integer, determine if it is a Palindrome in less than O(n) [on hold]

    - by user134235
    There is an O(n) solution to the problem of determining if an integer is a palindrome below. Is it possible to solve this problem in O(log n) or better? static void IsPalindrome(int Number) { int OrignalNum = Number; int Reverse = 0; int Remainder = 0; if (Number > 0) { while (Number > 0) { Remainder = Number % 10; Reverse = Reverse * 10 + Remainder; Number = Number / 10; } if (OrignalNum == Reverse) Console.WriteLine("It is a Palindrome"); else Console.WriteLine("It is not a Palindrome"); } else Console.WriteLine("Enter Number Again"); }

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  • problem to change my Xenserver password

    - by Michlaou
    I try to change my root password on my Xenserver 6.0. I follow these steps: enter boot: menu.c32 selecet xe-serial and press tab add "single" before the 2nd triple hyphens and i press enter. I have that: mboot.c32 /boot/xen.gz com1=115200,8n1 console=com1, vga mem=1024G dom0_max_vcpus4 dom0_mem=752M lowmem_emergency_pool=1M crashkernel=64M@32M single --- /boot/vmlinuz-2.6-xen root=LABEL=root-rodraxar ro console=tty0 xencons=hvc console=hvc0 --- /boot/initrd-2.6-xen.img I have commande on the screen and it's stop at: ext3-fs: monted filesystem with ordered data mode. Can you help me?

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