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  • A Method for Reducing Contention and Overhead in Worker Queues for Multithreaded Java Applications

    - by Janice J. Heiss
    A java.net article, rich in practical resources, by IBM India Labs’ Sathiskumar Palaniappan, Kavitha Varadarajan, and Jayashree Viswanathan, explores the challenge of writing code in a way that that effectively makes use of the resources of modern multicore processors and multiprocessor servers.As the article states: “Many server applications, such as Web servers, application servers, database servers, file servers, and mail servers, maintain worker queues and thread pools to handle large numbers of short tasks that arrive from remote sources. In general, a ‘worker queue’ holds all the short tasks that need to be executed, and the threads in the thread pool retrieve the tasks from the worker queue and complete the tasks. Since multiple threads act on the worker queue, adding tasks to and deleting tasks from the worker queue needs to be synchronized, which introduces contention in the worker queue.” The article goes on to explain ways that developers can reduce contention by maintaining one queue per thread. It also demonstrates a work-stealing technique that helps in effectively utilizing the CPU in multicore systems. Read the rest of the article here.

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  • Error java.lang.OutOfMemoryError: getNewTla using Oracle EPM products

    - by Marc Schumacher
    Running into a Java out of memory error, it is very common behaviour in the field that the Java heap size will be increased. While this might help to solve a heap space out of memory error, it might not help to fix an out of memory error for the Thread Local Area (TLA). Increasing the available heap space from 1 GB to 16 GB might not even help in this situation. The Thread Local Area (TLA) is part of the Java heap, but as the name already indicates, this memory area is local to a specific thread so there is no need to synchronize with other threads using this memory area. For optimization purposes the TLA size is configurable using the Java command line option “-XXtlasize”. Depending on the JRockit version and the available Java heap, the default values vary. Using Oracle EPM System (mainly 11.1.2.x) the following setting was tested successfully: -XXtlasize:min=8k,preferred=128k More information about the “-XXtlasize” parameter can be found in the JRockit documentation: http://docs.oracle.com/cd/E13150_01/jrockit_jvm/jrockit/jrdocs/refman/optionXX.html

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  • How To Get Web Site Thumbnail Image In ASP.NET

    - by SAMIR BHOGAYTA
    Overview One very common requirement of many web applications is to display a thumbnail image of a web site. A typical example is to provide a link to a dynamic website displaying its current thumbnail image, or displaying images of websites with their links as a result of search (I love to see it on Google). Microsoft .NET Framework 2.0 makes it quite easier to do it in a ASP.NET application. Background In order to generate image of a web page, first we need to load the web page to get their html code, and then this html needs to be rendered in a web browser. After that, a screen shot can be taken easily. I think there is no easier way to do this. Before .NET framework 2.0 it was quite difficult to use a web browser in C# or VB.NET because we either have to use COM+ interoperability or third party controls which becomes headache later. WebBrowser control in .NET framework 2.0 In .NET framework 2.0 we have a new Windows Forms WebBrowser control which is a wrapper around old shwdoc.dll. All you really need to do is to drop a WebBrowser control from your Toolbox on your form in .NET framework 2.0. If you have not used WebBrowser control yet, it's quite easy to use and very consistent with other Windows Forms controls. Some important methods of WebBrowser control are. public bool GoBack(); public bool GoForward(); public void GoHome(); public void GoSearch(); public void Navigate(Uri url); public void DrawToBitmap(Bitmap bitmap, Rectangle targetBounds); These methods are self explanatory with their names like Navigate function which redirects browser to provided URL. It also has a number of useful overloads. The DrawToBitmap (inherited from Control) draws the current image of WebBrowser to the provided bitmap. Using WebBrowser control in ASP.NET 2.0 The Solution Let's start to implement the solution which we discussed above. First we will define a static method to get the web site thumbnail image. public static Bitmap GetWebSiteThumbnail(string Url, int BrowserWidth, int BrowserHeight, int ThumbnailWidth, int ThumbnailHeight) { WebsiteThumbnailImage thumbnailGenerator = new WebsiteThumbnailImage(Url, BrowserWidth, BrowserHeight, ThumbnailWidth, ThumbnailHeight); return thumbnailGenerator.GenerateWebSiteThumbnailImage(); } The WebsiteThumbnailImage class will have a public method named GenerateWebSiteThumbnailImage which will generate the website thumbnail image in a separate STA thread and wait for the thread to exit. In this case, I decided to Join method of Thread class to block the initial calling thread until the bitmap is actually available, and then return the generated web site thumbnail. public Bitmap GenerateWebSiteThumbnailImage() { Thread m_thread = new Thread(new ThreadStart(_GenerateWebSiteThumbnailImage)); m_thread.SetApartmentState(ApartmentState.STA); m_thread.Start(); m_thread.Join(); return m_Bitmap; } The _GenerateWebSiteThumbnailImage will create a WebBrowser control object and navigate to the provided Url. We also register for the DocumentCompleted event of the web browser control to take screen shot of the web page. To pass the flow to the other controls we need to perform a method call to Application.DoEvents(); and wait for the completion of the navigation until the browser state changes to Complete in a loop. private void _GenerateWebSiteThumbnailImage() { WebBrowser m_WebBrowser = new WebBrowser(); m_WebBrowser.ScrollBarsEnabled = false; m_WebBrowser.Navigate(m_Url); m_WebBrowser.DocumentCompleted += new WebBrowserDocument CompletedEventHandler(WebBrowser_DocumentCompleted); while (m_WebBrowser.ReadyState != WebBrowserReadyState.Complete) Application.DoEvents(); m_WebBrowser.Dispose(); } The DocumentCompleted event will be fired when the navigation is completed and the browser is ready for screen shot. We will get screen shot using DrawToBitmap method as described previously which will return the bitmap of the web browser. Then the thumbnail image is generated using GetThumbnailImage method of Bitmap class passing it the required thumbnail image width and height. private void WebBrowser_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e) { WebBrowser m_WebBrowser = (WebBrowser)sender; m_WebBrowser.ClientSize = new Size(this.m_BrowserWidth, this.m_BrowserHeight); m_WebBrowser.ScrollBarsEnabled = false; m_Bitmap = new Bitmap(m_WebBrowser.Bounds.Width, m_WebBrowser.Bounds.Height); m_WebBrowser.BringToFront(); m_WebBrowser.DrawToBitmap(m_Bitmap, m_WebBrowser.Bounds); m_Bitmap = (Bitmap)m_Bitmap.GetThumbnailImage(m_ThumbnailWidth, m_ThumbnailHeight, null, IntPtr.Zero); } One more example here : http://www.codeproject.com/KB/aspnet/Website_URL_Screenshot.aspx

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  • A Look Inside JSR 360 - CLDC 8

    - by Roger Brinkley
    If you didn't notice during JavaOne the Java Micro Edition took a major step forward in its consolidation with Java Standard Edition when JSR 360 was proposed to the JCP community. Over the last couple of years there has been a focus to move Java ME back in line with it's big brother Java SE. We see evidence of this in JCP itself which just recently merged the ME and SE/EE Executive Committees into a single Java Executive Committee. But just before that occurred JSR 360 was proposed and approved for development on October 29. So let's take a look at what changes are now being proposed. In a way JSR 360 is returning back to the original roots of Java ME when it was first introduced. It was indeed a subset of the JDK 4 language, but as Java progressed many of the language changes were not implemented in the Java ME. Back then the tradeoff was still a functionality, footprint trade off but the major market was feature phones. Today the market has changed and CLDC, while it will still target feature phones, will have it primary emphasis on embedded devices like wireless modules, smart meters, health care monitoring and other M2M devices. The major changes will come in three areas: language feature changes, library changes, and consolidating the Generic Connection Framework.  There have been three Java SE versions that have been implemented since JavaME was first developed so the language feature changes can be divided into changes that came in JDK 5 and those in JDK 7, which mostly consist of the project Coin changes. There were no language changes in JDK 6 but the changes from JDK 5 are: Assertions - Assertions enable you to test your assumptions about your program. For example, if you write a method that calculates the speed of a particle, you might assert that the calculated speed is less than the speed of light. In the example code below if the interval isn't between 0 and and 1,00 the an error of "Invalid value?" would be thrown. private void setInterval(int interval) { assert interval > 0 && interval <= 1000 : "Invalid value?" } Generics - Generics add stability to your code by making more of your bugs detectable at compile time. Code that uses generics has many benefits over non-generic code with: Stronger type checks at compile time. Elimination of casts. Enabling programming to implement generic algorithms. Enhanced for Loop - the enhanced for loop allows you to iterate through a collection without having to create an Iterator or without having to calculate beginning and end conditions for a counter variable. The enhanced for loop is the easiest of the new features to immediately incorporate in your code. In this tip you will see how the enhanced for loop replaces more traditional ways of sequentially accessing elements in a collection. void processList(Vector<string> list) { for (String item : list) { ... Autoboxing/Unboxing - This facility eliminates the drudgery of manual conversion between primitive types, such as int and wrapper types, such as Integer.  Hashtable<Integer, string=""> data = new Hashtable<>(); void add(int id, String value) { data.put(id, value); } Enumeration - Prior to JDK 5 enumerations were not typesafe, had no namespace, were brittle because they were compile time constants, and provided no informative print values. JDK 5 added support for enumerated types as a full-fledged class (dubbed an enum type). In addition to solving all the problems mentioned above, it allows you to add arbitrary methods and fields to an enum type, to implement arbitrary interfaces, and more. Enum types provide high-quality implementations of all the Object methods. They are Comparable and Serializable, and the serial form is designed to withstand arbitrary changes in the enum type. enum Season {WINTER, SPRING, SUMMER, FALL}; } private Season season; void setSeason(Season newSeason) { season = newSeason; } Varargs - Varargs eliminates the need for manually boxing up argument lists into an array when invoking methods that accept variable-length argument lists. The three periods after the final parameter's type indicate that the final argument may be passed as an array or as a sequence of arguments. Varargs can be used only in the final argument position. void warning(String format, String... parameters) { .. for(String p : parameters) { ...process(p);... } ... } Static Imports -The static import construct allows unqualified access to static members without inheriting from the type containing the static members. Instead, the program imports the members either individually or en masse. Once the static members have been imported, they may be used without qualification. The static import declaration is analogous to the normal import declaration. Where the normal import declaration imports classes from packages, allowing them to be used without package qualification, the static import declaration imports static members from classes, allowing them to be used without class qualification. import static data.Constants.RATIO; ... double r = Math.cos(RATIO * theta); Annotations - Annotations provide data about a program that is not part of the program itself. They have no direct effect on the operation of the code they annotate. There are a number of uses for annotations including information for the compiler, compiler-time and deployment-time processing, and run-time processing. They can be applied to a program's declarations of classes, fields, methods, and other program elements. @Deprecated public void clear(); The language changes from JDK 7 are little more familiar as they are mostly the changes from Project Coin: String in switch - Hey it only took us 18 years but the String class can be used in the expression of a switch statement. Fortunately for us it won't take that long for JavaME to adopt it. switch (arg) { case "-data": ... case "-out": ... Binary integral literals and underscores in numeric literals - Largely for readability, the integral types (byte, short, int, and long) can also be expressed using the binary number system. and any number of underscore characters (_) can appear anywhere between digits in a numerical literal. byte flags = 0b01001111; long mask = 0xfff0_ff08_4fff_0fffl; Multi-catch and more precise rethrow - A single catch block can handle more than one type of exception. In addition, the compiler performs more precise analysis of rethrown exceptions than earlier releases of Java SE. This enables you to specify more specific exception types in the throws clause of a method declaration. catch (IOException | InterruptedException ex) { logger.log(ex); throw ex; } Type Inference for Generic Instance Creation - Otherwise known as the diamond operator, the type arguments required to invoke the constructor of a generic class can be replaced with an empty set of type parameters (<>) as long as the compiler can infer the type arguments from the context.  map = new Hashtable<>(); Try-with-resource statement - The try-with-resources statement is a try statement that declares one or more resources. A resource is an object that must be closed after the program is finished with it. The try-with-resources statement ensures that each resource is closed at the end of the statement.  try (DataInputStream is = new DataInputStream(...)) { return is.readDouble(); } Simplified varargs method invocation - The Java compiler generates a warning at the declaration site of a varargs method or constructor with a non-reifiable varargs formal parameter. Java SE 7 introduced a compiler option -Xlint:varargs and the annotations @SafeVarargs and @SuppressWarnings({"unchecked", "varargs"}) to supress these warnings. On the library side there are new features that will be added to satisfy the language requirements above and some to improve the currently available set of APIs.  The library changes include: Collections update - New Collection, List, Set and Map, Iterable and Iteratator as well as implementations including Hashtable and Vector. Most of the work is too support generics String - New StringBuilder and CharSequence as well as a Stirng formatter. The javac compiler  now uses the the StringBuilder instead of String Buffer. Since StringBuilder is synchronized there is a performance increase which has necessitated the wahat String constructor works. Comparable interface - The comparable interface works with Collections, making it easier to reuse. Try with resources - Closeable and AutoCloseable Annotations - While support for Annotations is provided it will only be a compile time support. SuppressWarnings, Deprecated, Override NIO - There is a subset of NIO Buffer that have been in use on the of the graphics packages and needs to be pulled in and also support for NIO File IO subset. Platform extensibility via Service Providers (ServiceLoader) - ServiceLoader interface dos late bindings of interface to existing implementations. It helpe to package an interface and behavior of the implementation at a later point in time.Provider classes must have a zero-argument constructor so that they can be instantiated during loading. They are located and instantiated on demand and are identified via a provider-configuration file in the METAINF/services resource directory. This is a mechansim from Java SE. import com.XYZ.ServiceA; ServiceLoader<ServiceA> sl1= new ServiceLoader(ServiceA.class); Resources: META-INF/services/com.XYZ.ServiceA: ServiceAProvider1 ServiceAProvider2 ServiceAProvider3 META-INF/services/ServiceB: ServiceBProvider1 ServiceBProvider2 From JSR - I would rather use this list I think The Generic Connection Framework (GCF) was previously specified in a number of different JSRs including CLDC, MIDP, CDC 1.2, and JSR 197. JSR 360 represents a rare opportunity to consolidated and reintegrate parts that were duplicated in other specifications into a single specification, upgrade the APIs as well provide new functionality. The proposal is to specify a combined GCF specification that can be used with Java ME or Java SE and be backwards compatible with previous implementations. Because of size limitations as well as the complexity of the some features like InvokeDynamic and Unicode 6 will not be included. Additionally, any language or library changes in JDK 8 will be not be included. On the upside, with all the changes being made, backwards compatibility will still be maintained. JSR 360 is a major step forward for Java ME in terms of platform modernization, language alignment, and embedded support. If you're interested in following the progress of this JSR see the JSR's java.net project for details of the email lists, discussions groups.

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  • Actor based concurrency and cancellation

    - by Akash
    I'm reading about actor based concurrency and I appreciate the simplicity of actors sequentially processing messages on a single thread. However there is one scenario that doesn't seen possible. Suppose that actor A sends a message to actor B, who then performs some long running task and returns a completion message to actor A. How can actor A force actor B to cancel the long running task after it has started? If actor B is running the task in its message queue thread, it won't pick up the cancellation message until it had completed the task; if actor B runs the task in a background thread then it seems to be violating the principle of actors. Is there a common way that this scenario is handled with actors? Or does each actor language/framework take a different approach? Or is this not a suitable problem to tackle via actors?

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  • Rewrite Generic URLs into real URLs on Google Analytics

    - by valdroni
    I have an iPhone app for a forum which also has a limited Google Analytics reporting. This app reports the page views in following generic form: /forum/67 /thread/29036 etc... The numbers above represent forum and thread ID's I am trying to set an Advanced filter, which will rewrite/report the page views in Google Analytics in following form: http://www.mysite.com/forum-67.html http://www.mysite.com/thread-29036.html Can someone please assist me in creating an Advanced Google Analytics filter which will enable me to see URL's so they can be live and send to correct page. Is there another method to achieve what I'm looking for ? Obviously there will be a need for some RegExp matches, but I cannot get around it.

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  • One True Event Loop

    - by CyberShadow
    Simple programs that collect data from only one system need only one event loop. For example, Windows applications have the message loop, POSIX network programs usually have a select/epoll/etc. loop at their core, pure SDL games use SDL's event loop. But what if you need to collect events from several subsystems? Such as an SDL game which doesn't use SDL_net for networking. I can think of several solutions: Polling (ugh) Put each event loop in its own thread, and: Send messages to the main thread, which collects and processes the events, or Place the event-processing code of each thread in a critical section, so that the threads can wait for events asynchronously but process them synchronously Choose one subsystem for the main event loop, and pass events from other subsystems via that subsystem as custom messages (for example, the Windows message loop and custom messages, or a socket select() loop and passing events via a loopback connection). Option 2.1 is more interesting on platforms where message-passing is a well-developed threading primitive (e.g. in the D programming language), but 2.2 looks like the best option to me.

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  • What is So Unique About Node.js?

    - by Adrian Shum
    Recently there has been a lot of praise for Node.js. I am not a developer that has had much exposure to network application. From my bare understanding of Nodes.js, its strength is: we have only one thread handling multiple connections, providing an event-based architecture. However, for example in Java, I can create only one thread using NIO/AIO (which is non-blocking APIs from my bare understanding), and handle multiple connections using that thread, and I provide an event-based architecture to implement the data handling logic (shouldn't be that difficult by providing some callback etc) ? Given JVM being a even more mature VM than V8 (I expect it to run faster too), and event-based handling architecture seems to be something not difficult to create, I am not sure why Node.js is attracting so much attention. Did I miss some important points?

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  • Why Nodes.js being that "unique"?

    - by Adrian Shum
    Recently years there are lots of praise to Nodes.js. I am not a developer that have much exposure on network application. From my bare understanding of Nodes.js, its strength is: We are having only on thread handling multiple connections, providing a event-based architecture. However, for example in Java, what if I am having only one thread, using NIO/AIO (which is non-blocking APIs from my bare understanding), and handle multiple connections using that thread, and I provide an event-based architecture to implement the data handling logic (shouldn't be that difficult by providing some callback etc) ? Given JVM being a even more mature VM than V8 (I expect it run faster too), and event-based handling architecture seems not something difficult to create. I am not sure why Nodes.js is attracting so much attention. Did I miss some important points?

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  • DIY Touch Screen Mod Makes Regular Gloves Smartphone-friendly

    - by Jason Fitzpatrick
    Smartphone-friendly winter gloves are expensive (and often ugly). Skip shelling out for store-bought gloves when, armed with a needle and thread, you can turn any gloves into smartphone-friendly ones. Over at Popular Science, Taylor Kubota shares the simple trick: 1. Order silver-plated nylon thread (silver conducts electricity). This can be difficult to find in stores, but major online retailers carry it. 2. Pick a pair of gloves to modify. Although leather works, it’s harder to push a needle through. 3. Stitch the figure of a star or other solid shape onto the glove’s index finger with the thread, making sure it will contact both the touchscreen and your skin. Our Geek Trivia App for Windows 8 is Now Available Everywhere How To Boot Your Android Phone or Tablet Into Safe Mode HTG Explains: Does Your Android Phone Need an Antivirus?

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  • Threading iPhone

    - by bobobobo
    Say I have a group of large meshes that I have to intersect rays against. Assume also, for whatever reason, I cannot further simplify/reduce poly check count by spatial subdivisioning. I can do this in parallel: bool intersects( list of meshes ) // a mesh is a group of triangles { create n threads foreach mesh in meshes assign to a thread in threads wait until ( threads.run() ) ; // run asynchronously // when they're all done // pull out intersected triangles // from per-thread context data } Can you do this in ios for games? Or is the overhead of thread creation and mutex waiting going to beat-out the benefit of multithreading?

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  • Is it safe to run multiple XNA ContentManager instances on multiple threads?

    - by Boinst
    My XNA project currently uses one ContentManager instance, and one dedicated background thread for loading all content. I wonder, would it be safe to have multiple ContentManager instances, each in it's own dedicated thread, loading different content at the same time? I'm prompted to ask this question because this article makes the following statement: If there are two textures created at the same time on different threads, they will clobber the other and you will end up with some garbage in the textures. I think that what the author is saying here, is that if I access one ContentManager simultaneously on two threads, I'll get garbage. But what if I have separate ContentManager instances for each thread? If no-one knows the answer already from experience, I'll go ahead and try it and see what happens.

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  • 3 threads printing numbers of different range

    - by user875036
    This question was asked in an Electronic Arts interview: There are 3 threads. The first thread prints the numbers 1 to 10. The second thread prints the numbers 11 to 20. The third thread prints the numbers from from 21 to 30. Now, all three threads are running. The numbers are printed in an irregular order like 1, 11, 2, 21, 12 etc. If I want numbers to be printed in sorted order like 1, 2, 3, 4..., what should I do with these threads?

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  • Do games use threads?

    - by Nubcake
    I understand that the concept of how a game runs i.e while (game_loop = true) { //handle events // input/output/sound etc } But it has come to my attention while programming in another HLL is do some games use threads for certain operations? For example take any Pokemon game ; during interaction a textbox appears to display information. Now I've been trying to simulate that sort of textbox and the only way I could have got it to be exactly the same is by using a loop and yes once a loop is started there is no way to handle window events unless they are handled again inside the loop itself. I couldn't have used this loop inside a different thread other than the main one (due to a DirectX limitation) so the only option was to use it inside the main program thread. I was wondering if some games work like this ; do they only use the main program thread and handle events again if they're inside a loop? Edit: I forgot to mention this is about console games not PC games! Thanks Nubcake

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  • Why doesn't my implementation of ElGamal work for long text strings?

    - by angstrom91
    I'm playing with the El Gamal cryptosystem, and my goal is to be able to encipher and decipher long sequences of text. I have come up with a method that works for short sequences, but does not work for long sequences, and I cannot figure out why. El Gamal requires the plaintext to be an integer. I have turned my string into a byte[] using the .getBytes() method for Strings, and then created a BigInteger out of the byte[]. After encryption/decryption, I turn the BigInteger into a byte[] using the .toByteArray() method for BigIntegers, and then create a new String object from the byte[]. This works perfectly when i call ElGamalEncipher with strings up to 129 characters. With 130 or more characters, the output produced from ElGamalDecipher is garbled. Can someone suggest how to solve this issue? Is this an issue with my method of turning the string into a BigInteger? If so, is there a better way to turn my string of text into a BigInteger and back? Below is my encipher/decipher code with a program to demonstrate the problem. import java.math.BigInteger; public class Main { static BigInteger P = new BigInteger("15893293927989454301918026303382412" + "2586402937727056707057089173871237566896685250125642378268385842" + "6917261652781627945428519810052550093673226849059197769795219973" + "9423619267147615314847625134014485225178547696778149706043781174" + "2873134844164791938367765407368476144402513720666965545242487520" + "288928241768306844169"); static BigInteger G = new BigInteger("33234037774370419907086775226926852" + "1714093595439329931523707339920987838600777935381196897157489391" + "8360683761941170467795379762509619438720072694104701372808513985" + "2267495266642743136795903226571831274837537691982486936010899433" + "1742996138863988537349011363534657200181054004755211807985189183" + "22832092343085067869"); static BigInteger R = new BigInteger("72294619754760174015019300613282868" + "7219874058383991405961870844510501809885568825032608592198728334" + "7842806755320938980653857292210955880919036195738252708294945320" + "3969657021169134916999794791553544054426668823852291733234236693" + "4178738081619274342922698767296233937873073756955509269717272907" + "8566607940937442517"); static BigInteger A = new BigInteger("32189274574111378750865973746687106" + "3695160924347574569923113893643975328118502246784387874381928804" + "6865920942258286938666201264395694101012858796521485171319748255" + "4630425677084511454641229993833255506759834486100188932905136959" + "7287419551379203001848457730376230681693887924162381650252270090" + "28296990388507680954"); public static void main(String[] args) { FewChars(); System.out.println(); ManyChars(); } public static void FewChars() { //ElGamalEncipher(String plaintext, BigInteger p, BigInteger g, BigInteger r) BigInteger[] cipherText = ElGamal.ElGamalEncipher("This is a string " + "of 129 characters which works just fine . This is a string " + "of 129 characters which works just fine . This is a s", P, G, R); System.out.println("This is a string of 129 characters which works " + "just fine . This is a string of 129 characters which works " + "just fine . This is a s"); //ElGamalDecipher(BigInteger c, BigInteger d, BigInteger a, BigInteger p) System.out.println("The decrypted text is: " + ElGamal.ElGamalDecipher(cipherText[0], cipherText[1], A, P)); } public static void ManyChars() { //ElGamalEncipher(String plaintext, BigInteger p, BigInteger g, BigInteger r) BigInteger[] cipherText = ElGamal.ElGamalEncipher("This is a string " + "of 130 characters which doesn’t work! This is a string of " + "130 characters which doesn’t work! This is a string of ", P, G, R); System.out.println("This is a string of 130 characters which doesn’t " + "work! This is a string of 130 characters which doesn’t work!" + " This is a string of "); //ElGamalDecipher(BigInteger c, BigInteger d, BigInteger a, BigInteger p) System.out.println("The decrypted text is: " + ElGamal.ElGamalDecipher(cipherText[0], cipherText[1], A, P)); } } import java.math.BigInteger; import java.security.SecureRandom; public class ElGamal { public static BigInteger[] ElGamalEncipher(String plaintext, BigInteger p, BigInteger g, BigInteger r) { // returns a BigInteger[] cipherText // cipherText[0] is c // cipherText[1] is d SecureRandom sr = new SecureRandom(); BigInteger[] cipherText = new BigInteger[2]; BigInteger pText = new BigInteger(plaintext.getBytes()); // 1: select a random integer k such that 1 <= k <= p-2 BigInteger k = new BigInteger(p.bitLength() - 2, sr); // 2: Compute c = g^k(mod p) BigInteger c = g.modPow(k, p); // 3: Compute d= P*r^k = P(g^a)^k(mod p) BigInteger d = pText.multiply(r.modPow(k, p)).mod(p); // C =(c,d) is the ciphertext cipherText[0] = c; cipherText[1] = d; return cipherText; } public static String ElGamalDecipher(BigInteger c, BigInteger d, BigInteger a, BigInteger p) { //returns the plaintext enciphered as (c,d) // 1: use the private key a to compute the least non-negative residue // of an inverse of (c^a)' (mod p) BigInteger z = c.modPow(a, p).modInverse(p); BigInteger P = z.multiply(d).mod(p); byte[] plainTextArray = P.toByteArray(); return new String(plainTextArray); } }

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  • Android SQLlite crashes after trying retrieving data from it

    - by Pavel
    Hey everyone. I'm kinda new to android programming so please bear with me. I'm having some problems with retrieving records from the db. Basically, all I want to do is to store latitudes and longitudes which GPS positioning functions outputs and display them in a list using ListActivity on different tab later on. This is how the code for my DBAdapter helper class looks like: public class DBAdapter { public static final String KEY_ROWID = "_id"; public static final String KEY_LATITUDE = "latitude"; public static final String KEY_LONGITUDE = "longitude"; private static final String TAG = "DBAdapter"; private static final String DATABASE_NAME = "coords"; private static final String DATABASE_TABLE = "coordsStorage"; private static final int DATABASE_VERSION = 1; private static final String DATABASE_CREATE = "create table coordsStorage (_id integer primary key autoincrement, " + "latitude integer not null, longitude integer not null);"; private final Context context; private DatabaseHelper DBHelper; private SQLiteDatabase db; public DBAdapter(Context ctx) { this.context = ctx; DBHelper = new DatabaseHelper(context); } private static class DatabaseHelper extends SQLiteOpenHelper { DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL(DATABASE_CREATE); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { Log.w(TAG, "Upgrading database from version " + oldVersion + " to " + newVersion + ", which will destroy all old data"); db.execSQL("DROP TABLE IF EXISTS titles"); onCreate(db); } } //---opens the database--- public DBAdapter open() throws SQLException { db = DBHelper.getWritableDatabase(); return this; } //---closes the database--- public void close() { DBHelper.close(); } //---insert a title into the database--- public long insertCoords(int latitude, int longitude) { ContentValues initialValues = new ContentValues(); initialValues.put(KEY_LATITUDE, latitude); initialValues.put(KEY_LONGITUDE, longitude); return db.insert(DATABASE_TABLE, null, initialValues); } //---deletes a particular title--- public boolean deleteTitle(long rowId) { return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) 0; } //---retrieves all the titles--- public Cursor getAllTitles() { return db.query(DATABASE_TABLE, new String[] { KEY_ROWID, KEY_LATITUDE, KEY_LONGITUDE}, null, null, null, null, null); } //---retrieves a particular title--- public Cursor getTitle(long rowId) throws SQLException { Cursor mCursor = db.query(true, DATABASE_TABLE, new String[] { KEY_ROWID, KEY_LATITUDE, KEY_LONGITUDE}, KEY_ROWID + "=" + rowId, null, null, null, null, null); if (mCursor != null) { mCursor.moveToFirst(); } return mCursor; } //---updates a title--- /*public boolean updateTitle(long rowId, int latitude, int longitude) { ContentValues args = new ContentValues(); args.put(KEY_LATITUDE, latitude); args.put(KEY_LONGITUDE, longitude); return db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) 0; }*/ } Now my question is - am I doing something wrong here? If yes could someone please tell me what? And how I should retrieve the records in organised list manner? Help would be greatly appreciated!!

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  • 3-way quicksort, question

    - by peiska
    I am trying to understand the 3-way radix Quicksort, and i dont understand why the the CUTOFF variable there? and the insertion method? public class Quick3string { private static final int CUTOFF = 15; // cutoff to insertion sort // sort the array a[] of strings public static void sort(String[] a) { // StdRandom.shuffle(a); sort(a, 0, a.length-1, 0); assert isSorted(a); } // return the dth character of s, -1 if d = length of s private static int charAt(String s, int d) { assert d >= 0 && d <= s.length(); if (d == s.length()) return -1; return s.charAt(d); } // 3-way string quicksort a[lo..hi] starting at dth character private static void sort(String[] a, int lo, int hi, int d) { // cutoff to insertion sort for small subarrays if (hi <= lo + CUTOFF) { insertion(a, lo, hi, d); return; } int lt = lo, gt = hi; int v = charAt(a[lo], d); int i = lo + 1; while (i <= gt) { int t = charAt(a[i], d); if (t < v) exch(a, lt++, i++); else if (t > v) exch(a, i, gt--); else i++; } // a[lo..lt-1] < v = a[lt..gt] < a[gt+1..hi]. sort(a, lo, lt-1, d); if (v >= 0) sort(a, lt, gt, d+1); sort(a, gt+1, hi, d); } // sort from a[lo] to a[hi], starting at the dth character private static void insertion(String[] a, int lo, int hi, int d) { for (int i = lo; i <= hi; i++) for (int j = i; j > lo && less(a[j], a[j-1], d); j--) exch(a, j, j-1); } // exchange a[i] and a[j] private static void exch(String[] a, int i, int j) { String temp = a[i]; a[i] = a[j]; a[j] = temp; } // is v less than w, starting at character d private static boolean less(String v, String w, int d) { assert v.substring(0, d).equals(w.substring(0, d)); return v.substring(d).compareTo(w.substring(d)) < 0; } // is the array sorted private static boolean isSorted(String[] a) { for (int i = 1; i < a.length; i++) if (a[i].compareTo(a[i-1]) < 0) return false; return true; } public static void main(String[] args) { // read in the strings from standard input String[] a = StdIn.readAll().split("\\s+"); int N = a.length; // sort the strings sort(a); // print the results for (int i = 0; i < N; i++) StdOut.println(a[i]); } } from http://www.cs.princeton.edu/algs4/51radix/Quick3string.java.html

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  • DropDownList and SelectListItem Array Item Updates in MVC

    - by Rick Strahl
    So I ran into an interesting behavior today as I deployed my first MVC 4 app tonight. I have a list form that has a filter drop down that allows selection of categories. This list is static and rarely changes so rather than loading these items from the database each time I load the items once and then cache the actual SelectListItem[] array in a static property. However, when we put the site online tonight we immediately noticed that the drop down list was coming up with pre-set values that randomly changed. Didn't take me long to trace this back to the cached list of SelectListItem[]. Clearly the list was getting updated - apparently through the model binding process in the selection postback. To clarify the scenario here's the drop down list definition in the Razor View:@Html.DropDownListFor(mod => mod.QueryParameters.Category, Model.CategoryList, "All Categories") where Model.CategoryList gets set with:[HttpPost] [CompressContent] public ActionResult List(MessageListViewModel model) { InitializeViewModel(model); busEntry entryBus = new busEntry(); var entries = entryBus.GetEntryList(model.QueryParameters); model.Entries = entries; model.DisplayMode = ApplicationDisplayModes.Standard; model.CategoryList = AppUtils.GetCachedCategoryList(); return View(model); } The AppUtils.GetCachedCategoryList() method gets the cached list or loads the list on the first access. The code to load up the list is housed in a Web utility class. The method looks like this:/// <summary> /// Returns a static category list that is cached /// </summary> /// <returns></returns> public static SelectListItem[] GetCachedCategoryList() { if (_CategoryList != null) return _CategoryList; lock (_SyncLock) { if (_CategoryList != null) return _CategoryList; var catBus = new busCategory(); var categories = catBus.GetCategories().ToList(); // Turn list into a SelectItem list var catList= categories .Select(cat => new SelectListItem() { Text = cat.Name, Value = cat.Id.ToString() }) .ToList(); catList.Insert(0, new SelectListItem() { Value = ((int)SpecialCategories.AllCategoriesButRealEstate).ToString(), Text = "All Categories except Real Estate" }); catList.Insert(1, new SelectListItem() { Value = "-1", Text = "--------------------------------" }); _CategoryList = catList.ToArray(); } return _CategoryList; } private static SelectListItem[] _CategoryList ; This seemed normal enough to me - I've been doing stuff like this forever caching smallish lists in memory to avoid an extra trip to the database. This list is used in various places throughout the application - for the list display and also when adding new items and setting up for notifications etc.. Watch that ModelBinder! However, it turns out that this code is clearly causing a problem. It appears that the model binder on the [HttpPost] method is actually updating the list that's bound to and changing the actual entry item in the list and setting its selected value. If you look at the code above I'm not setting the SelectListItem.Selected value anywhere - the only place this value can get set is through ModelBinding. Sure enough when stepping through the code I see that when an item is selected the actual model - model.CategoryList[x].Selected - reflects that. This is bad on several levels: First it's obviously affecting the application behavior - nobody wants to see their drop down list values jump all over the place randomly. But it's also a problem because the array is getting updated by multiple ASP.NET threads which likely would lead to odd crashes from time to time. Not good! In retrospect the modelbinding behavior makes perfect sense. The actual items and the Selected property is the ModelBinder's way of keeping track of one or more selected values. So while I assumed the list to be read-only, the ModelBinder is actually updating it on a post back producing the rather surprising results. Totally missed this during testing and is another one of those little - "Did you know?" moments. So, is there a way around this? Yes but it's maybe not quite obvious. I can't change the behavior of the ModelBinder, but I can certainly change the way that the list is generated. Rather than returning the cached list, I can return a brand new cloned list from the cached items like this:/// <summary> /// Returns a static category list that is cached /// </summary> /// <returns></returns> public static SelectListItem[] GetCachedCategoryList() { if (_CategoryList != null) { // Have to create new instances via projection // to avoid ModelBinding updates to affect this // globally return _CategoryList .Select(cat => new SelectListItem() { Value = cat.Value, Text = cat.Text }) .ToArray(); } …}  The key is that newly created instances of SelectListItems are returned not just filtered instances of the original list. The key here is 'new instances' so that the ModelBinding updates do not update the actual static instance. The code above uses LINQ and a projection into new SelectListItem instances to create this array of fresh instances. And this code works correctly - no more cross-talk between users. Unfortunately this code is also less efficient - it has to reselect the items and uses extra memory for the new array. Knowing what I know now I probably would have not cached the list and just take the hit to read from the database. If there is even a possibility of thread clashes I'm very wary of creating code like this. But since the method already exists and handles this load in one place this fix was easy enough to put in. Live and learn. It's little things like this that can cause some interesting head scratchers sometimes…© Rick Strahl, West Wind Technologies, 2005-2012Posted in MVC  ASP.NET  .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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  • Sending Messages to SignalR Hubs from the Outside

    - by Ricardo Peres
    Introduction You are by now probably familiarized with SignalR, Microsoft’s API for real-time web functionality. This is, in my opinion, one of the greatest products Microsoft has released in recent time. Usually, people login to a site and enter some page which is connected to a SignalR hub. Then they can send and receive messages – not just text messages, mind you – to other users in the same hub. Also, the server can also take the initiative to send messages to all or a specified subset of users on its own, this is known as server push. The normal flow is pretty straightforward, Microsoft has done a great job with the API, it’s clean and quite simple to use. And for the latter – the server taking the initiative – it’s also quite simple, just involves a little more work. The Problem The API for sending messages can be achieved from inside a hub – an instance of the Hub class – which is something that we don’t have if we are the server and we want to send a message to some user or group of users: the Hub instance is only instantiated in response to a client message. The Solution It is possible to acquire a hub’s context from outside of an actual Hub instance, by calling GlobalHost.ConnectionManager.GetHubContext<T>(). This API allows us to: Broadcast messages to all connected clients (possibly excluding some); Send messages to a specific client; Send messages to a group of clients. So, we have groups and clients, each is identified by a string. Client strings are called connection ids and group names are free-form, given by us. The problem with client strings is, we do not know how these map to actual users. One way to achieve this mapping is by overriding the Hub’s OnConnected and OnDisconnected methods and managing the association there. Here’s an example: 1: public class MyHub : Hub 2: { 3: private static readonly IDictionary<String, ISet<String>> users = new ConcurrentDictionary<String, ISet<String>>(); 4:  5: public static IEnumerable<String> GetUserConnections(String username) 6: { 7: ISet<String> connections; 8:  9: users.TryGetValue(username, out connections); 10:  11: return (connections ?? Enumerable.Empty<String>()); 12: } 13:  14: private static void AddUser(String username, String connectionId) 15: { 16: ISet<String> connections; 17:  18: if (users.TryGetValue(username, out connections) == false) 19: { 20: connections = users[username] = new HashSet<String>(); 21: } 22:  23: connections.Add(connectionId); 24: } 25:  26: private static void RemoveUser(String username, String connectionId) 27: { 28: users[username].Remove(connectionId); 29: } 30:  31: public override Task OnConnected() 32: { 33: AddUser(this.Context.Request.User.Identity.Name, this.Context.ConnectionId); 34: return (base.OnConnected()); 35: } 36:  37: public override Task OnDisconnected() 38: { 39: RemoveUser(this.Context.Request.User.Identity.Name, this.Context.ConnectionId); 40: return (base.OnDisconnected()); 41: } 42: } As you can see, I am using a static field to store the mapping between a user and its possibly many connections – for example, multiple open browser tabs or even multiple browsers accessing the same page with the same login credentials. The user identity, as is normal in .NET, is obtained from the IPrincipal which in SignalR hubs case is stored in Context.Request.User. Of course, this property will only have a meaningful value if we enforce authentication. Another way to go is by creating a group for each user that connects: 1: public class MyHub : Hub 2: { 3: public override Task OnConnected() 4: { 5: this.Groups.Add(this.Context.ConnectionId, this.Context.Request.User.Identity.Name); 6: return (base.OnConnected()); 7: } 8:  9: public override Task OnDisconnected() 10: { 11: this.Groups.Remove(this.Context.ConnectionId, this.Context.Request.User.Identity.Name); 12: return (base.OnDisconnected()); 13: } 14: } In this case, we will have a one-to-one equivalence between users and groups. All connections belonging to the same user will fall in the same group. So, if we want to send messages to a user from outside an instance of the Hub class, we can do something like this, for the first option – user mappings stored in a static field: 1: public void SendUserMessage(String username, String message) 2: { 3: var context = GlobalHost.ConnectionManager.GetHubContext<MyHub>(); 4: 5: foreach (String connectionId in HelloHub.GetUserConnections(username)) 6: { 7: context.Clients.Client(connectionId).sendUserMessage(message); 8: } 9: } And for using groups, its even simpler: 1: public void SendUserMessage(String username, String message) 2: { 3: var context = GlobalHost.ConnectionManager.GetHubContext<MyHub>(); 4:  5: context.Clients.Group(username).sendUserMessage(message); 6: } Using groups has the advantage that the IHubContext interface returned from GetHubContext has direct support for groups, no need to send messages to individual connections. Of course, you can wrap both mapping options in a common API, perhaps exposed through IoC. One example of its interface might be: 1: public interface IUserToConnectionMappingService 2: { 3: //associate and dissociate connections to users 4:  5: void AddUserConnection(String username, String connectionId); 6:  7: void RemoveUserConnection(String username, String connectionId); 8: } SignalR has built-in dependency resolution, by means of the static GlobalHost.DependencyResolver property: 1: //for using groups (in the Global class) 2: GlobalHost.DependencyResolver.Register(typeof(IUserToConnectionMappingService), () => new GroupsMappingService()); 3:  4: //for using a static field (in the Global class) 5: GlobalHost.DependencyResolver.Register(typeof(IUserToConnectionMappingService), () => new StaticMappingService()); 6:  7: //retrieving the current service (in the Hub class) 8: var mapping = GlobalHost.DependencyResolver.Resolve<IUserToConnectionMappingService>(); Now all you have to do is implement GroupsMappingService and StaticMappingService with the code I shown here and change SendUserMessage method to rely in the dependency resolver for the actual implementation. Stay tuned for more SignalR posts!

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  • How to use ULS in SharePoint 2010 for Custom Code Exception Logging?

    - by venkatx5
    What is ULS in SharePoint 2010? ULS stands for Unified Logging Service which captures and writes Exceptions/Logs in Log File(A Plain Text File with .log extension). SharePoint logs Each and every exceptions with ULS. SharePoint Administrators should know ULS and it's very useful when anything goes wrong. but when you ask any SharePoint 2007 Administrator to check log file then most of them will Kill you. Because read and understand the log file is not so easy. Imagine open a plain text file of 20 MB in NotePad and go thru line by line. Now Microsoft developed a tool "ULS Viewer" to view those Log files in easily readable format. This tools also helps to filter events based on exception priority. You can read on this blog to know in details about ULS Viewer . Where to get ULS Viewer? ULS Viewer is developed by Microsoft and available to download for free. URL : http://code.msdn.microsoft.com/ULSViewer/Release/ProjectReleases.aspx?ReleaseId=3308 Note: Eventhought this tool developed by Microsoft, it's not supported by Microsoft. Means you can't support for this tool from Microsoft and use it on your own Risk. By the way what's the risk in viewing Log Files?! How to use ULS in SharePoint 2010 Custom Code? ULS can be extended to use in user solutions to log exceptions. In Detail, Developer can use ULS to log his own application errors and exceptions on SharePoint Log files. So now all in Single Place (That's why it's called "Unified Logging"). Well in this article I am going to use Waldek's Code (Reference Link). However the article is core and am writing container for that (Basically how to implement the code in Detail). Let's see the steps. Open Visual Studio 2010 -> File -> New Project -> Visual C# -> Windows -> Class Library -> Name : ULSLogger (Make sure you've selected .net Framework 3.5)   In Solution Explorer Panel, Rename the Class1.cs to LoggingService.cs   Right Click on References -> Add Reference -> Under .Net tab select "Microsoft.SharePoint"   Right Click on the Project -> Properties. Select "Signing" Tab -> Check "Sign the Assembly".   In the below drop down select <New> and enter "ULSLogger", uncheck the "Protect my key with a Password" option.   Now copy the below code and paste. (Or Just refer.. :-) ) using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.SharePoint; using Microsoft.SharePoint.Administration; using System.Runtime.InteropServices; namespace ULSLogger { public class LoggingService : SPDiagnosticsServiceBase { public static string vsDiagnosticAreaName = "Venkats SharePoint Logging Service"; public static string CategoryName = "vsProject"; public static uint uintEventID = 700; // Event ID private static LoggingService _Current; public static LoggingService Current {  get   {    if (_Current == null)     {       _Current = new LoggingService();     }    return _Current;   } }private LoggingService() : base("Venkats SharePoint Logging Service", SPFarm.Local) {}protected override IEnumerable<SPDiagnosticsArea> ProvideAreas() { List<SPDiagnosticsArea> areas = new List<SPDiagnosticsArea>  {   new SPDiagnosticsArea(vsDiagnosticAreaName, new List<SPDiagnosticsCategory>    {     new SPDiagnosticsCategory(CategoryName, TraceSeverity.Medium, EventSeverity.Error)    })   }; return areas; }public static string LogErrorInULS(string errorMessage) { string strExecutionResult = "Message Not Logged in ULS. "; try  {   SPDiagnosticsCategory category = LoggingService.Current.Areas[vsDiagnosticAreaName].Categories[CategoryName];   LoggingService.Current.WriteTrace(uintEventID, category, TraceSeverity.Unexpected, errorMessage);   strExecutionResult = "Message Logged"; } catch (Exception ex) {  strExecutionResult += ex.Message; } return strExecutionResult; }public static string LogErrorInULS(string errorMessage, TraceSeverity tsSeverity) { string strExecutionResult = "Message Not Logged in ULS. "; try  {  SPDiagnosticsCategory category = LoggingService.Current.Areas[vsDiagnosticAreaName].Categories[CategoryName];  LoggingService.Current.WriteTrace(uintEventID, category, tsSeverity, errorMessage);  strExecutionResult = "Message Logged";  } catch (Exception ex)  {   strExecutionResult += ex.Message;   } return strExecutionResult;  } } }   Just build the solution and it's ready to use now. This ULS solution can be used in SharePoint Webparts or Console Application. Lets see how to use it in a Console Application. SharePoint Server 2010 must be installed in the same Server or the application must be hosted in SharPoint Server 2010 environment. The console application must be set to "x64" Platform target.   Create a New Console Application. (Visual Studio -> File -> New Project -> C# -> Windows -> Console Application) Right Click on References -> Add Reference -> Under .Net tab select "Microsoft.SharePoint" Open Program.cs add "using Microsoft.SharePoint.Administration;" Right Click on References -> Add Reference -> Under "Browse" tab select the "ULSLogger.dll" which we created first. (Path : ULSLogger\ULSLogger\bin\Debug\) Right Click on Project -> Properties -> Select "Build" Tab -> Under "Platform Target" option select "x64". Open the Program.cs and paste the below code. using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.SharePoint.Administration; using ULSLogger; namespace ULSLoggerClient {  class Program   {   static void Main(string[] args)     {     Console.WriteLine("ULS Logging Started.");     string strResult = LoggingService.LogErrorInULS("My Application is Working Fine.");      Console.WriteLine("ULS Logging Info. Result : " + strResult);     string strResult = LoggingService.LogErrorInULS("My Application got an Exception.", TraceSeverity.High);     Console.WriteLine("ULS Logging Waring Result : " + strResult);      Console.WriteLine("ULS Logging Completed.");      Console.ReadLine();     }   } } Just build the solution and execute. It'll log the message on the log file. Make sure you are using Farm Administrator User ID. You can play with Message and TraceSeverity as required. Now Open ULS Viewer -> File -> Open From -> ULS -> Select First Option to open the default ULS Log. It's Uls RealTime and will show all log entries in readable table format. Right Click on a row and select "Filter By This Item". Select "Event ID" and enter value "700" that we used in the application. Click Ok and now you'll see the Exceptions/Logs which logged by our application.   If you want to see High Priority Messages only then Click Icons except Red Cross Icon on the Toolbar. The tooltip will tell what's the icons used for.

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  • SDL_BlitSurface segmentation fault (surfaces aren't null)

    - by Trollkemada
    My app is crashing on SDL_BlitSurface() and i can't figure out why. I think it has something to do with my static object. If you read the code you'll why I think so. This happens when the limits of the map are reached, i.e. (iwidth || jheight). This is the code: Map.cpp (this render) Tile const * Map::getTyle(int i, int j) const { if (i >= 0 && j >= 0 && i < width && j < height) { return data[i][j]; } else { return &Tile::ERROR_TYLE; // This makes SDL_BlitSurface (called later) crash //return new Tile(TileType::ERROR); // This works with not problem (but is memory leak, of course) } } void Map::render(int x, int y, int width, int height) const { //DEBUG("(Rendering...) x: "<<x<<", y: "<<y<<", width: "<<width<<", height: "<<height); int firstI = x / TileType::PIXEL_PER_TILE; int firstJ = y / TileType::PIXEL_PER_TILE; int lastI = (x+width) / TileType::PIXEL_PER_TILE; int lastJ = (y+height) / TileType::PIXEL_PER_TILE; // The previous integer division rounds down when dealing with positive values, but it rounds up // negative values. This is a fix for that (We need those values always rounded down) if (firstI < 0) { firstI--; } if (firstJ < 0) { firstJ--; } const int firstX = x; const int firstY = y; SDL_Rect srcRect; SDL_Rect dstRect; for (int i=firstI; i <= lastI; i++) { for (int j=firstJ; j <= lastJ; j++) { if (i*TileType::PIXEL_PER_TILE < x) { srcRect.x = x % TileType::PIXEL_PER_TILE; srcRect.w = TileType::PIXEL_PER_TILE - (x % TileType::PIXEL_PER_TILE); dstRect.x = i*TileType::PIXEL_PER_TILE + (x % TileType::PIXEL_PER_TILE) - firstX; } else if (i*TileType::PIXEL_PER_TILE >= x + width) { srcRect.x = 0; srcRect.w = x % TileType::PIXEL_PER_TILE; dstRect.x = i*TileType::PIXEL_PER_TILE - firstX; } else { srcRect.x = 0; srcRect.w = TileType::PIXEL_PER_TILE; dstRect.x = i*TileType::PIXEL_PER_TILE - firstX; } if (j*TileType::PIXEL_PER_TILE < y) { srcRect.y = 0; srcRect.h = TileType::PIXEL_PER_TILE - (y % TileType::PIXEL_PER_TILE); dstRect.y = j*TileType::PIXEL_PER_TILE + (y % TileType::PIXEL_PER_TILE) - firstY; } else if (j*TileType::PIXEL_PER_TILE >= y + height) { srcRect.y = y % TileType::PIXEL_PER_TILE; srcRect.h = y % TileType::PIXEL_PER_TILE; dstRect.y = j*TileType::PIXEL_PER_TILE - firstY; } else { srcRect.y = 0; srcRect.h = TileType::PIXEL_PER_TILE; dstRect.y = j*TileType::PIXEL_PER_TILE - firstY; } SDL::YtoSDL(dstRect.y, srcRect.h); SDL_BlitSurface(getTyle(i,j)->getType()->getSurface(), &srcRect, SDL::getScreen(), &dstRect); // <-- Crash HERE /*DEBUG("i = "<<i<<", j = "<<j); DEBUG("srcRect.x = "<<srcRect.x<<", srcRect.y = "<<srcRect.y<<", srcRect.w = "<<srcRect.w<<", srcRect.h = "<<srcRect.h); DEBUG("dstRect.x = "<<dstRect.x<<", dstRect.y = "<<dstRect.y);*/ } } } Tile.h #ifndef TILE_H #define TILE_H #include "TileType.h" class Tile { private: TileType const * type; public: static const Tile ERROR_TYLE; Tile(TileType const * t); ~Tile(); TileType const * getType() const; }; #endif Tile.cpp #include "Tile.h" const Tile Tile::ERROR_TYLE(TileType::ERROR); Tile::Tile(TileType const * t) : type(t) {} Tile::~Tile() {} TileType const * Tile::getType() const { return type; } TileType.h #ifndef TILETYPE_H #define TILETYPE_H #include "SDL.h" #include "DEBUG.h" class TileType { protected: TileType(); ~TileType(); public: static const int PIXEL_PER_TILE = 30; static const TileType * ERROR; static const TileType * AIR; static const TileType * SOLID; virtual SDL_Surface * getSurface() const = 0; virtual bool isSolid(int x, int y) const = 0; }; #endif ErrorTyle.h #ifndef ERRORTILE_H #define ERRORTILE_H #include "TileType.h" class ErrorTile : public TileType { friend class TileType; private: ErrorTile(); mutable SDL_Surface * surface; static const char * FILE_PATH; public: SDL_Surface * getSurface() const; bool isSolid(int x, int y) const ; }; #endif ErrorTyle.cpp (The surface can't be loaded when building the object, because it is a static object and SDL_Init() needs to be called first) #include "ErrorTile.h" const char * ErrorTile::FILE_PATH = ("C:\\error.bmp"); ErrorTile::ErrorTile() : TileType(), surface(NULL) {} SDL_Surface * ErrorTile::getSurface() const { if (surface == NULL) { if (SDL::isOn()) { surface = SDL::loadAndOptimice(ErrorTile::FILE_PATH); if (surface->w != TileType::PIXEL_PER_TILE || surface->h != TileType::PIXEL_PER_TILE) { WARNING("Bad tile surface size"); } } else { ERROR("Trying to load a surface, but SDL is not on"); } } if (surface == NULL) { // This if doesn't get called, so surface != NULL ERROR("WTF? Can't load surface :\\"); } return surface; } bool ErrorTile::isSolid(int x, int y) const { return true; }

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  • Invalid algorithm specified on Windows 2003 Server only

    - by JL
    I am decoding a file using the following method: string outFileName = zfoFileName.Replace(".zfo", "_tmp.zfo"); FileStream inFile = null; FileStream outFile = null; inFile = File.Open(zfoFileName, FileMode.Open); outFile = File.Create(outFileName); LargeCMS.CMS cms = new LargeCMS.CMS(); cms.Decode(inFile, outFile); This is working fine on my Win 7 dev machine, but on a Windows 2003 server production machine it fails with the following exception: Exception: System.Exception: CryptMsgUpdate error #-2146893816 --- System.ComponentModel.Win32Exception: Invalid algorithm specified --- End of inner exception stack trace --- at LargeCMS.CMS.Decode(FileStream inFile, FileStream outFile) Here are the classes below which I call to do the decoding, if needed I can upload a sample file for decoding, its just strange it works on Win 7, and not on Win2k3 server: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO; using System.Security.Cryptography; using System.Security.Cryptography.X509Certificates; using System.Runtime.InteropServices; using System.ComponentModel; namespace LargeCMS { class CMS { // File stream to use in callback function private FileStream m_callbackFile; // Streaming callback function for encoding private Boolean StreamOutputCallback(IntPtr pvArg, IntPtr pbData, int cbData, Boolean fFinal) { // Write all bytes to encoded file Byte[] bytes = new Byte[cbData]; Marshal.Copy(pbData, bytes, 0, cbData); m_callbackFile.Write(bytes, 0, cbData); if (fFinal) { // This is the last piece. Close the file m_callbackFile.Flush(); m_callbackFile.Close(); m_callbackFile = null; } return true; } // Encode CMS with streaming to support large data public void Encode(X509Certificate2 cert, FileStream inFile, FileStream outFile) { // Variables Win32.CMSG_SIGNER_ENCODE_INFO SignerInfo; Win32.CMSG_SIGNED_ENCODE_INFO SignedInfo; Win32.CMSG_STREAM_INFO StreamInfo; Win32.CERT_CONTEXT[] CertContexts = null; Win32.BLOB[] CertBlobs; X509Chain chain = null; X509ChainElement[] chainElements = null; X509Certificate2[] certs = null; RSACryptoServiceProvider key = null; BinaryReader stream = null; GCHandle gchandle = new GCHandle(); IntPtr hProv = IntPtr.Zero; IntPtr SignerInfoPtr = IntPtr.Zero; IntPtr CertBlobsPtr = IntPtr.Zero; IntPtr hMsg = IntPtr.Zero; IntPtr pbPtr = IntPtr.Zero; Byte[] pbData; int dwFileSize; int dwRemaining; int dwSize; Boolean bResult = false; try { // Get data to encode dwFileSize = (int)inFile.Length; stream = new BinaryReader(inFile); pbData = stream.ReadBytes(dwFileSize); // Prepare stream for encoded info m_callbackFile = outFile; // Get cert chain chain = new X509Chain(); chain.Build(cert); chainElements = new X509ChainElement[chain.ChainElements.Count]; chain.ChainElements.CopyTo(chainElements, 0); // Get certs in chain certs = new X509Certificate2[chainElements.Length]; for (int i = 0; i < chainElements.Length; i++) { certs[i] = chainElements[i].Certificate; } // Get context of all certs in chain CertContexts = new Win32.CERT_CONTEXT[certs.Length]; for (int i = 0; i < certs.Length; i++) { CertContexts[i] = (Win32.CERT_CONTEXT)Marshal.PtrToStructure(certs[i].Handle, typeof(Win32.CERT_CONTEXT)); } // Get cert blob of all certs CertBlobs = new Win32.BLOB[CertContexts.Length]; for (int i = 0; i < CertContexts.Length; i++) { CertBlobs[i].cbData = CertContexts[i].cbCertEncoded; CertBlobs[i].pbData = CertContexts[i].pbCertEncoded; } // Get CSP of client certificate key = (RSACryptoServiceProvider)certs[0].PrivateKey; bResult = Win32.CryptAcquireContext( ref hProv, key.CspKeyContainerInfo.KeyContainerName, key.CspKeyContainerInfo.ProviderName, key.CspKeyContainerInfo.ProviderType, 0 ); if (!bResult) { throw new Exception("CryptAcquireContext error #" + Marshal.GetLastWin32Error().ToString(), new Win32Exception(Marshal.GetLastWin32Error())); } // Populate Signer Info struct SignerInfo = new Win32.CMSG_SIGNER_ENCODE_INFO(); SignerInfo.cbSize = Marshal.SizeOf(SignerInfo); SignerInfo.pCertInfo = CertContexts[0].pCertInfo; SignerInfo.hCryptProvOrhNCryptKey = hProv; SignerInfo.dwKeySpec = (int)key.CspKeyContainerInfo.KeyNumber; SignerInfo.HashAlgorithm.pszObjId = Win32.szOID_OIWSEC_sha1; // Populate Signed Info struct SignedInfo = new Win32.CMSG_SIGNED_ENCODE_INFO(); SignedInfo.cbSize = Marshal.SizeOf(SignedInfo); SignedInfo.cSigners = 1; SignerInfoPtr = Marshal.AllocHGlobal(Marshal.SizeOf(SignerInfo)); Marshal.StructureToPtr(SignerInfo, SignerInfoPtr, false); SignedInfo.rgSigners = SignerInfoPtr; SignedInfo.cCertEncoded = CertBlobs.Length; CertBlobsPtr = Marshal.AllocHGlobal(Marshal.SizeOf(CertBlobs[0]) * CertBlobs.Length); for (int i = 0; i < CertBlobs.Length; i++) { Marshal.StructureToPtr(CertBlobs[i], new IntPtr(CertBlobsPtr.ToInt64() + (Marshal.SizeOf(CertBlobs[i]) * i)), false); } SignedInfo.rgCertEncoded = CertBlobsPtr; // Populate Stream Info struct StreamInfo = new Win32.CMSG_STREAM_INFO(); StreamInfo.cbContent = dwFileSize; StreamInfo.pfnStreamOutput = new Win32.StreamOutputCallbackDelegate(StreamOutputCallback); // TODO: CMSG_DETACHED_FLAG // Open message to encode hMsg = Win32.CryptMsgOpenToEncode( Win32.X509_ASN_ENCODING | Win32.PKCS_7_ASN_ENCODING, 0, Win32.CMSG_SIGNED, ref SignedInfo, null, ref StreamInfo ); if (hMsg.Equals(IntPtr.Zero)) { throw new Exception("CryptMsgOpenToEncode error #" + Marshal.GetLastWin32Error().ToString(), new Win32Exception(Marshal.GetLastWin32Error())); } // Process the whole message gchandle = GCHandle.Alloc(pbData, GCHandleType.Pinned); pbPtr = gchandle.AddrOfPinnedObject(); dwRemaining = dwFileSize; dwSize = (dwFileSize < 1024 * 1000 * 100) ? dwFileSize : 1024 * 1000 * 100; while (dwRemaining > 0) { // Update message piece by piece bResult = Win32.CryptMsgUpdate( hMsg, pbPtr, dwSize, (dwRemaining <= dwSize) ? true : false ); if (!bResult) { throw new Exception("CryptMsgUpdate error #" + Marshal.GetLastWin32Error().ToString(), new Win32Exception(Marshal.GetLastWin32Error())); } // Move to the next piece pbPtr = new IntPtr(pbPtr.ToInt64() + dwSize); dwRemaining -= dwSize; if (dwRemaining < dwSize) { dwSize = dwRemaining; } } } finally { // Clean up if (gchandle.IsAllocated) { gchandle.Free(); } if (stream != null) { stream.Close(); } if (m_callbackFile != null) { m_callbackFile.Close(); } if (!CertBlobsPtr.Equals(IntPtr.Zero)) { Marshal.FreeHGlobal(CertBlobsPtr); } if (!SignerInfoPtr.Equals(IntPtr.Zero)) { Marshal.FreeHGlobal(SignerInfoPtr); } if (!hProv.Equals(IntPtr.Zero)) { Win32.CryptReleaseContext(hProv, 0); } if (!hMsg.Equals(IntPtr.Zero)) { Win32.CryptMsgClose(hMsg); } } } // Decode CMS with streaming to support large data public void Decode(FileStream inFile, FileStream outFile) { // Variables Win32.CMSG_STREAM_INFO StreamInfo; Win32.CERT_CONTEXT SignerCertContext; BinaryReader stream = null; GCHandle gchandle = new GCHandle(); IntPtr hMsg = IntPtr.Zero; IntPtr pSignerCertInfo = IntPtr.Zero; IntPtr pSignerCertContext = IntPtr.Zero; IntPtr pbPtr = IntPtr.Zero; IntPtr hStore = IntPtr.Zero; Byte[] pbData; Boolean bResult = false; int dwFileSize; int dwRemaining; int dwSize; int cbSignerCertInfo; try { // Get data to decode dwFileSize = (int)inFile.Length; stream = new BinaryReader(inFile); pbData = stream.ReadBytes(dwFileSize); // Prepare stream for decoded info m_callbackFile = outFile; // Populate Stream Info struct StreamInfo = new Win32.CMSG_STREAM_INFO(); StreamInfo.cbContent = dwFileSize; StreamInfo.pfnStreamOutput = new Win32.StreamOutputCallbackDelegate(StreamOutputCallback); // Open message to decode hMsg = Win32.CryptMsgOpenToDecode( Win32.X509_ASN_ENCODING | Win32.PKCS_7_ASN_ENCODING, 0, 0, IntPtr.Zero, IntPtr.Zero, ref StreamInfo ); if (hMsg.Equals(IntPtr.Zero)) { throw new Exception("CryptMsgOpenToDecode error #" + Marshal.GetLastWin32Error().ToString(), new Win32Exception(Marshal.GetLastWin32Error())); } // Process the whole message gchandle = GCHandle.Alloc(pbData, GCHandleType.Pinned); pbPtr = gchandle.AddrOfPinnedObject(); dwRemaining = dwFileSize; dwSize = (dwFileSize < 1024 * 1000 * 100) ? dwFileSize : 1024 * 1000 * 100; while (dwRemaining > 0) { // Update message piece by piece bResult = Win32.CryptMsgUpdate( hMsg, pbPtr, dwSize, (dwRemaining <= dwSize) ? true : false ); if (!bResult) { throw new Exception("CryptMsgUpdate error #" + Marshal.GetLastWin32Error().ToString(), new Win32Exception(Marshal.GetLastWin32Error())); } // Move to the next piece pbPtr = new IntPtr(pbPtr.ToInt64() + dwSize); dwRemaining -= dwSize; if (dwRemaining < dwSize) { dwSize = dwRemaining; } } // Get signer certificate info cbSignerCertInfo = 0; bResult = Win32.CryptMsgGetParam( hMsg, Win32.CMSG_SIGNER_CERT_INFO_PARAM, 0, IntPtr.Zero, ref cbSignerCertInfo ); if (!bResult) { throw new Exception("CryptMsgGetParam error #" + Marshal.GetLastWin32Error().ToString(), new Win32Exception(Marshal.GetLastWin32Error())); } pSignerCertInfo = Marshal.AllocHGlobal(cbSignerCertInfo); bResult = Win32.CryptMsgGetParam( hMsg, Win32.CMSG_SIGNER_CERT_INFO_PARAM, 0, pSignerCertInfo, ref cbSignerCertInfo ); if (!bResult) { throw new Exception("CryptMsgGetParam error #" + Marshal.GetLastWin32Error().ToString(), new Win32Exception(Marshal.GetLastWin32Error())); } // Open a cert store in memory with the certs from the message hStore = Win32.CertOpenStore( Win32.CERT_STORE_PROV_MSG, Win32.X509_ASN_ENCODING | Win32.PKCS_7_ASN_ENCODING, IntPtr.Zero, 0, hMsg ); if (hStore.Equals(IntPtr.Zero)) { throw new Exception("CertOpenStore error #" + Marshal.GetLastWin32Error().ToString(), new Win32Exception(Marshal.GetLastWin32Error())); } // Find the signer's cert in the store pSignerCertContext = Win32.CertGetSubjectCertificateFromStore( hStore, Win32.X509_ASN_ENCODING | Win32.PKCS_7_ASN_ENCODING, pSignerCertInfo ); if (pSignerCertContext.Equals(IntPtr.Zero)) { throw new Exception("CertGetSubjectCertificateFromStore error #" + Marshal.GetLastWin32Error().ToString(), new Win32Exception(Marshal.GetLastWin32Error())); } // Set message for verifying SignerCertContext = (Win32.CERT_CONTEXT)Marshal.PtrToStructure(pSignerCertContext, typeof(Win32.CERT_CONTEXT)); bResult = Win32.CryptMsgControl( hMsg, 0, Win32.CMSG_CTRL_VERIFY_SIGNATURE, SignerCertContext.pCertInfo ); if (!bResult) { throw new Exception("CryptMsgControl error #" + Marshal.GetLastWin32Error().ToString(), new Win32Exception(Marshal.GetLastWin32Error())); } } finally { // Clean up if (gchandle.IsAllocated) { gchandle.Free(); } if (!pSignerCertContext.Equals(IntPtr.Zero)) { Win32.CertFreeCertificateContext(pSignerCertContext); } if (!pSignerCertInfo.Equals(IntPtr.Zero)) { Marshal.FreeHGlobal(pSignerCertInfo); } if (!hStore.Equals(IntPtr.Zero)) { Win32.CertCloseStore(hStore, Win32.CERT_CLOSE_STORE_FORCE_FLAG); } if (stream != null) { stream.Close(); } if (m_callbackFile != null) { m_callbackFile.Close(); } if (!hMsg.Equals(IntPtr.Zero)) { Win32.CryptMsgClose(hMsg); } } } } } and using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.InteropServices; using System.Security.Cryptography.X509Certificates; using System.ComponentModel; using System.Security.Cryptography; namespace LargeCMS { class Win32 { #region "CONSTS" public const int X509_ASN_ENCODING = 0x00000001; public const int PKCS_7_ASN_ENCODING = 0x00010000; public const int CMSG_SIGNED = 2; public const int CMSG_DETACHED_FLAG = 0x00000004; public const int AT_KEYEXCHANGE = 1; public const int AT_SIGNATURE = 2; public const String szOID_OIWSEC_sha1 = "1.3.14.3.2.26"; public const int CMSG_CTRL_VERIFY_SIGNATURE = 1; public const int CMSG_CERT_PARAM = 12; public const int CMSG_SIGNER_CERT_INFO_PARAM = 7; public const int CERT_STORE_PROV_MSG = 1; public const int CERT_CLOSE_STORE_FORCE_FLAG = 1; #endregion #region "STRUCTS" [StructLayout(LayoutKind.Sequential)] public struct CRYPT_ALGORITHM_IDENTIFIER { public String pszObjId; BLOB Parameters; } [StructLayout(LayoutKind.Sequential)] public struct CERT_ID { public int dwIdChoice; public BLOB IssuerSerialNumberOrKeyIdOrHashId; } [StructLayout(LayoutKind.Sequential)] public struct CMSG_SIGNER_ENCODE_INFO { public int cbSize; public IntPtr pCertInfo; public IntPtr hCryptProvOrhNCryptKey; public int dwKeySpec; public CRYPT_ALGORITHM_IDENTIFIER HashAlgorithm; public IntPtr pvHashAuxInfo; public int cAuthAttr; public IntPtr rgAuthAttr; public int cUnauthAttr; public IntPtr rgUnauthAttr; public CERT_ID SignerId; public CRYPT_ALGORITHM_IDENTIFIER HashEncryptionAlgorithm; public IntPtr pvHashEncryptionAuxInfo; } [StructLayout(LayoutKind.Sequential)] public struct CERT_CONTEXT { public int dwCertEncodingType; public IntPtr pbCertEncoded; public int cbCertEncoded; public IntPtr pCertInfo; public IntPtr hCertStore; } [StructLayout(LayoutKind.Sequential)] public struct BLOB { public int cbData; public IntPtr pbData; } [StructLayout(LayoutKind.Sequential)] public struct CMSG_SIGNED_ENCODE_INFO { public int cbSize; public int cSigners; public IntPtr rgSigners; public int cCertEncoded; public IntPtr rgCertEncoded; public int cCrlEncoded; public IntPtr rgCrlEncoded; public int cAttrCertEncoded; public IntPtr rgAttrCertEncoded; } [StructLayout(LayoutKind.Sequential)] public struct CMSG_STREAM_INFO { public int cbContent; public StreamOutputCallbackDelegate pfnStreamOutput; public IntPtr pvArg; } #endregion #region "DELEGATES" public delegate Boolean StreamOutputCallbackDelegate(IntPtr pvArg, IntPtr pbData, int cbData, Boolean fFinal); #endregion #region "API" [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)] public static extern Boolean CryptAcquireContext( ref IntPtr hProv, String pszContainer, String pszProvider, int dwProvType, int dwFlags ); [DllImport("Crypt32.dll", SetLastError = true)] public static extern IntPtr CryptMsgOpenToEncode( int dwMsgEncodingType, int dwFlags, int dwMsgType, ref CMSG_SIGNED_ENCODE_INFO pvMsgEncodeInfo, String pszInnerContentObjID, ref CMSG_STREAM_INFO pStreamInfo ); [DllImport("Crypt32.dll", SetLastError = true)] public static extern IntPtr CryptMsgOpenToDecode( int dwMsgEncodingType, int dwFlags, int dwMsgType, IntPtr hCryptProv, IntPtr pRecipientInfo, ref CMSG_STREAM_INFO pStreamInfo ); [DllImport("Crypt32.dll", SetLastError = true)] public static extern Boolean CryptMsgClose( IntPtr hCryptMsg ); [DllImport("Crypt32.dll", SetLastError = true)] public static extern Boolean CryptMsgUpdate( IntPtr hCryptMsg, Byte[] pbData, int cbData, Boolean fFinal ); [DllImport("Crypt32.dll", SetLastError = true)] public static extern Boolean CryptMsgUpdate( IntPtr hCryptMsg, IntPtr pbData, int cbData, Boolean fFinal ); [DllImport("Crypt32.dll", SetLastError = true)] public static extern Boolean CryptMsgGetParam( IntPtr hCryptMsg, int dwParamType, int dwIndex, IntPtr pvData, ref int pcbData ); [DllImport("Crypt32.dll", SetLastError = true)] public static extern Boolean CryptMsgControl( IntPtr hCryptMsg, int dwFlags, int dwCtrlType, IntPtr pvCtrlPara ); [DllImport("advapi32.dll", SetLastError = true)] public static extern Boolean CryptReleaseContext( IntPtr hProv, int dwFlags ); [DllImport("Crypt32.dll", SetLastError = true)] public static extern IntPtr CertCreateCertificateContext( int dwCertEncodingType, IntPtr pbCertEncoded, int cbCertEncoded ); [DllImport("Crypt32.dll", SetLastError = true)] public static extern Boolean CertFreeCertificateContext( IntPtr pCertContext ); [DllImport("Crypt32.dll", SetLastError = true)] public static extern IntPtr CertOpenStore( int lpszStoreProvider, int dwMsgAndCertEncodingType, IntPtr hCryptProv, int dwFlags, IntPtr pvPara ); [DllImport("Crypt32.dll", SetLastError = true)] public static extern IntPtr CertGetSubjectCertificateFromStore( IntPtr hCertStore, int dwCertEncodingType, IntPtr pCertId ); [DllImport("Crypt32.dll", SetLastError = true)] public static extern IntPtr CertCloseStore( IntPtr hCertStore, int dwFlags ); #endregion } }

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  • Calling AuditQuerySystemPolicy() (advapi32.dll) from C# returns "The parameter is incorrect"

    - by JCCyC
    The sequence is like follows: Open a policy handle with LsaOpenPolicy() (not shown) Call LsaQueryInformationPolicy() to get the number of categories; For each category: Call AuditLookupCategoryGuidFromCategoryId() to turn the enum value into a GUID; Call AuditEnumerateSubCategories() to get a list of the GUIDs of all subcategories; Call AuditQuerySystemPolicy() to get the audit policies for the subcategories. All of these work and return expected, sensible values except the last. Calling AuditQuerySystemPolicy() gets me a "The parameter is incorrect" error. I'm thinking there must be some subtle unmarshaling problem. I'm probably misinterpreting what exactly AuditEnumerateSubCategories() returns, but I'm stumped. You'll see (commented) I tried to dereference the return pointer from AuditEnumerateSubCategories() as a pointer. Doing or not doing that gives the same result. Code: #region LSA types public enum POLICY_INFORMATION_CLASS { PolicyAuditLogInformation = 1, PolicyAuditEventsInformation, PolicyPrimaryDomainInformation, PolicyPdAccountInformation, PolicyAccountDomainInformation, PolicyLsaServerRoleInformation, PolicyReplicaSourceInformation, PolicyDefaultQuotaInformation, PolicyModificationInformation, PolicyAuditFullSetInformation, PolicyAuditFullQueryInformation, PolicyDnsDomainInformation } public enum POLICY_AUDIT_EVENT_TYPE { AuditCategorySystem, AuditCategoryLogon, AuditCategoryObjectAccess, AuditCategoryPrivilegeUse, AuditCategoryDetailedTracking, AuditCategoryPolicyChange, AuditCategoryAccountManagement, AuditCategoryDirectoryServiceAccess, AuditCategoryAccountLogon } [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)] public struct POLICY_AUDIT_EVENTS_INFO { public bool AuditingMode; public IntPtr EventAuditingOptions; public UInt32 MaximumAuditEventCount; } [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)] public struct GUID { public UInt32 Data1; public UInt16 Data2; public UInt16 Data3; public Byte Data4a; public Byte Data4b; public Byte Data4c; public Byte Data4d; public Byte Data4e; public Byte Data4f; public Byte Data4g; public Byte Data4h; public override string ToString() { return Data1.ToString("x8") + "-" + Data2.ToString("x4") + "-" + Data3.ToString("x4") + "-" + Data4a.ToString("x2") + Data4b.ToString("x2") + "-" + Data4c.ToString("x2") + Data4d.ToString("x2") + Data4e.ToString("x2") + Data4f.ToString("x2") + Data4g.ToString("x2") + Data4h.ToString("x2"); } } #endregion #region LSA Imports [DllImport("kernel32.dll")] extern static int GetLastError(); [DllImport("advapi32.dll", CharSet = CharSet.Unicode, PreserveSig = true)] public static extern UInt32 LsaNtStatusToWinError( long Status); [DllImport("advapi32.dll", CharSet = CharSet.Unicode, PreserveSig = true)] public static extern long LsaOpenPolicy( ref LSA_UNICODE_STRING SystemName, ref LSA_OBJECT_ATTRIBUTES ObjectAttributes, Int32 DesiredAccess, out IntPtr PolicyHandle ); [DllImport("advapi32.dll", CharSet = CharSet.Unicode, PreserveSig = true)] public static extern long LsaClose(IntPtr PolicyHandle); [DllImport("advapi32.dll", CharSet = CharSet.Unicode, PreserveSig = true)] public static extern long LsaFreeMemory(IntPtr Buffer); [DllImport("advapi32.dll", CharSet = CharSet.Unicode, PreserveSig = true)] public static extern void AuditFree(IntPtr Buffer); [DllImport("advapi32.dll", SetLastError = true, PreserveSig = true)] public static extern long LsaQueryInformationPolicy( IntPtr PolicyHandle, POLICY_INFORMATION_CLASS InformationClass, out IntPtr Buffer); [DllImport("advapi32.dll", SetLastError = true, PreserveSig = true)] public static extern bool AuditLookupCategoryGuidFromCategoryId( POLICY_AUDIT_EVENT_TYPE AuditCategoryId, IntPtr pAuditCategoryGuid); [DllImport("advapi32.dll", SetLastError = true, PreserveSig = true)] public static extern bool AuditEnumerateSubCategories( IntPtr pAuditCategoryGuid, bool bRetrieveAllSubCategories, out IntPtr ppAuditSubCategoriesArray, out ulong pCountReturned); [DllImport("advapi32.dll", SetLastError = true, PreserveSig = true)] public static extern bool AuditQuerySystemPolicy( IntPtr pSubCategoryGuids, ulong PolicyCount, out IntPtr ppAuditPolicy); #endregion Dictionary<string, UInt32> retList = new Dictionary<string, UInt32>(); long lretVal; uint retVal; IntPtr pAuditEventsInfo; lretVal = LsaQueryInformationPolicy(policyHandle, POLICY_INFORMATION_CLASS.PolicyAuditEventsInformation, out pAuditEventsInfo); retVal = LsaNtStatusToWinError(lretVal); if (retVal != 0) { LsaClose(policyHandle); throw new System.ComponentModel.Win32Exception((int)retVal); } POLICY_AUDIT_EVENTS_INFO myAuditEventsInfo = new POLICY_AUDIT_EVENTS_INFO(); myAuditEventsInfo = (POLICY_AUDIT_EVENTS_INFO)Marshal.PtrToStructure(pAuditEventsInfo, myAuditEventsInfo.GetType()); IntPtr subCats = IntPtr.Zero; ulong nSubCats = 0; for (int audCat = 0; audCat < myAuditEventsInfo.MaximumAuditEventCount; audCat++) { GUID audCatGuid = new GUID(); if (!AuditLookupCategoryGuidFromCategoryId((POLICY_AUDIT_EVENT_TYPE)audCat, new IntPtr(&audCatGuid))) { int causingError = GetLastError(); LsaFreeMemory(pAuditEventsInfo); LsaClose(policyHandle); throw new System.ComponentModel.Win32Exception(causingError); } if (!AuditEnumerateSubCategories(new IntPtr(&audCatGuid), true, out subCats, out nSubCats)) { int causingError = GetLastError(); LsaFreeMemory(pAuditEventsInfo); LsaClose(policyHandle); throw new System.ComponentModel.Win32Exception(causingError); } // Dereference the first pointer-to-pointer to point to the first subcategory // subCats = (IntPtr)Marshal.PtrToStructure(subCats, subCats.GetType()); if (nSubCats > 0) { IntPtr audPolicies = IntPtr.Zero; if (!AuditQuerySystemPolicy(subCats, nSubCats, out audPolicies)) { int causingError = GetLastError(); if (subCats != IntPtr.Zero) AuditFree(subCats); LsaFreeMemory(pAuditEventsInfo); LsaClose(policyHandle); throw new System.ComponentModel.Win32Exception(causingError); } AUDIT_POLICY_INFORMATION myAudPol = new AUDIT_POLICY_INFORMATION(); for (ulong audSubCat = 0; audSubCat < nSubCats; audSubCat++) { // Process audPolicies[audSubCat], turn GUIDs into names, fill retList. // http://msdn.microsoft.com/en-us/library/aa373931%28VS.85%29.aspx // http://msdn.microsoft.com/en-us/library/bb648638%28VS.85%29.aspx IntPtr itemAddr = IntPtr.Zero; IntPtr itemAddrAddr = new IntPtr(audPolicies.ToInt64() + (long)(audSubCat * (ulong)Marshal.SizeOf(itemAddr))); itemAddr = (IntPtr)Marshal.PtrToStructure(itemAddrAddr, itemAddr.GetType()); myAudPol = (AUDIT_POLICY_INFORMATION)Marshal.PtrToStructure(itemAddr, myAudPol.GetType()); retList[myAudPol.AuditSubCategoryGuid.ToString()] = myAudPol.AuditingInformation; } if (audPolicies != IntPtr.Zero) AuditFree(audPolicies); } if (subCats != IntPtr.Zero) AuditFree(subCats); subCats = IntPtr.Zero; nSubCats = 0; } lretVal = LsaFreeMemory(pAuditEventsInfo); retVal = LsaNtStatusToWinError(lretVal); if (retVal != 0) throw new System.ComponentModel.Win32Exception((int)retVal); lretVal = LsaClose(policyHandle); retVal = LsaNtStatusToWinError(lretVal); if (retVal != 0) throw new System.ComponentModel.Win32Exception((int)retVal);

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  • DLLImport error: System.AccessViolationException with Manifest file and c#

    - by RP
    When trying to call (DLLImport) an external c++ dll from a .net application that has a manifest file with requireAdministrator, I get this error trying to call function from the C++ dll in Windows 7 with UAC enabled. Method I am calling: EnCrypts System.AccessViolationException: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. public class BlowFish { [DllImport("BlowfishTool.dll", CharSet = CharSet.Auto)] public static extern String EnCrypt(String strData, String strPassword); [DllImport("BlowfishTool.dll", CharSet = CharSet.Auto)] public static extern String EnCrypt(String strData, String strPassword, bool doNotUsePassChecking); [DllImport("BlowfishTool.dll", CharSet = CharSet.Auto)] public static extern String DeCrypt(String strData, String strPassword, bool doNotUsePassChecking); [DllImport("BlowfishTool.dll", CharSet = CharSet.Auto)] public static extern String DeCrypt(String strData, String strPassword); public static String EnCrypts(String strData, String strPassword) { return EnCrypt(strData, strPassword, true); } } }

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  • Handy ASP.NET MVC 2 Extension Methods &ndash; Where am I?

    - by Bobby Diaz
    Have you ever needed to detect what part of the application is currently being viewed?  This might be a bigger issue if you write a lot of shared/partial views or custom display or editor templates.  Another scenario, which is the one I encountered when I first started down this path, is when you have some type of menu and you’d like to be able to determine which item represents the current page so you can highlight it in some way.  A simple example is the menu that is created as part of the default ASP.NET MVC 2 Application template.   <div id="menucontainer">       <ul id="menu">         <li><%= Html.ActionLink("Home", "Index", "Home") %></li>         <li><%= Html.ActionLink("About", "About", "Home") %></li>     </ul>   </div>   The part that got me at first, however, was the following entry in the default style sheet (Site.css):   ul#menu li.selected a {     background-color: #fff;     color: #000; }   I assumed that the .selected class would automatically get applied to the active menu item.  After trying a few different things, including the MvcContrib MenuBuilder, I decided to write my own extension methods so I would have more control over the output.  First, I needed a way to determine what view the user has navigated to based on the requested URL and route configuration.  Now, I am sure there are many ways to do this, but this is what I came up with:   public static class RequestExtensions {     public static bool IsCurrentRoute(this RequestContext context, String areaName,         String controllerName, params String[] actionNames)     {         var routeData = context.RouteData;         var routeArea = routeData.DataTokens["area"] as String;         var current = false;           if ( ((String.IsNullOrEmpty(routeArea) && String.IsNullOrEmpty(areaName)) ||               (routeArea == areaName)) &&              ((String.IsNullOrEmpty(controllerName)) ||               (routeData.GetRequiredString("controller") == controllerName)) &&              ((actionNames == null) ||                actionNames.Contains(routeData.GetRequiredString("action"))) )         {             current = true;         }           return current;     }       // additional overloads omitted... }   With that in place, I was able to write several UrlHelper methods that check if the supplied values map to the current view.   public static class UrlExtensions {     public static bool IsCurrent(this UrlHelper urlHelper, String areaName,         String controllerName, params String[] actionNames)     {         return urlHelper.RequestContext.IsCurrentRoute(areaName, controllerName, actionNames);     }       public static string Selected(this UrlHelper urlHelper, String areaName,         String controllerName, params String[] actionNames)     {         return urlHelper.IsCurrent(areaName, controllerName, actionNames)             ? "selected" : String.Empty;     }       // additional overloads omitted... }   Now I can re-work the original menu to utilize these new methods.  Note: be sure to import the proper namespace so the extension methods become available inside your views!   <div id="menucontainer">       <ul id="menu">         <li class="<%= Url.Selected(null, "Home", "Index") %>">             <%= Html.ActionLink("Home", "Index", "Home")%></li>           <li class="<%= Url.Selected(null, "Home", "About") %>">             <%= Html.ActionLink("About", "About", "Home")%></li>     </ul>   </div>   If we take it one step further, we can clean up the markup even more.  Check out the Html.ActionMenuItem() extension method and the refined menu:   public static class HtmlExtensions {     public static MvcHtmlString ActionMenuItem(this HtmlHelper htmlHelper, String linkText,         String actionName, String controllerName)     {         var html = new StringBuilder("<li");           if ( htmlHelper.ViewContext.RequestContext                 .IsCurrentRoute(null, controllerName, actionName) )         {             html.Append(" class=\"selected\"");         }           html.Append(">")             .Append(htmlHelper.ActionLink(linkText, actionName, controllerName))             .Append("</li>");           return MvcHtmlString.Create(html.ToString());     }       // additional overloads omitted... }   <div id="menucontainer">       <ul id="menu">         <%= Html.ActionMenuItem("Home", "Index", "Home") %>         <%= Html.ActionMenuItem("About", "About", "Home") %>     </ul>   </div>   Which generates the following HTML:   <div id="menucontainer">       <ul id="menu">         <li class="selected"><a href="/">Home</a></li>         <li><a href="/Home/About">About</a></li>     </ul>   </div>     I have created a codepaste of these extension methods if you are interested in using them in your own projects.  Enjoy!

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