out parameter - Page 284

Type for use in template object to compare double values

- by DaClown

I got this n-dimensional point object: template <class T, unsigned int dimension> class Obj { protected: T coords[dimension]; static const unsigned int size = dimension; public: Obj() { }; Obj(T def) { for (unsigned int i = 0; i < size; ++i) coords[i]=def; }; Obj(const Obj& o) { for (unsigned int i = 0; i < size; ++i) coords[i] = o.coords[i]; } const Obj& operator= (const Obj& rhs) { if (this != &rhs) for (unsigned int i = 0; i < size; ++i) coords[i] = rhs.coords[i]; return *this; } virtual ~Obj() { }; T get (unsigned int id) { if (id >= size) throw std::out_of_range("out of range"); return coords[id]; } void set (unsigned int id, T t) { if (id >= size) throw std::out_of_range("out of range"); coords[id] = t; } }; and a 3D point class which uses Obj as base class: template <class U> class Point3DBase : public Obj<U,3> { typedef U type; public: U &x, &y, &z; public: Point3DBase() : x(Obj<U,3>::coords[0]), y(Obj<U,3>::coords[1]), z(Obj<U,3>::coords[2]) { }; Point3DBase(U def) : Obj<U,3>(def), x(Obj<U,3>::coords[0]), y(Obj<U,3>::coords[1]), z(Obj<U,3>::coords[2]) { }; Point3DBase(U x_, U y_, U z_) : x(Obj<U,3>::coords[0]), y(Obj<U,3>::coords[1]), z(Obj<U,3>::coords[2]) { x = x_; y = y_; z= z_; }; Point3DBase(const Point3DBase& other) : x(Obj<U,3>::coords[0]), y(Obj<U,3>::coords[1]), z(Obj<U,3>::coords[2]) { x = other.x; y = other.y; z = other.z; } // several operators ... }; The operators, basically the ones for comparison, use the simple compare-the-member-object approach like: virtual friend bool operator== (const Point3DBase<U> &lhs, const Point3DBase<U> rhs) { return (lhs.x == rhs.x && lhs.y == rhs.y && lhs.z == rhs.z); } Then it occured to me that for the comparion of double values the simply equality approach is not very useful since double values should be compared with an error margin. What would be the best approach to introduce an error margin into the point? I thought about an epsDouble type as template parameter but I can't figure out how to achieve this.

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Fill container with template parameters

- by phlipsy

I want to fill the template parameters passed to a variadic template into an array with fixed length. For that purpose I wrote the following helper function templates template<typename ForwardIterator, typename T> void fill(ForwardIterator i) { } template<typename ForwardIterator, typename T, T head, T... tail> void fill(ForwardIterator i) { *i = head; fill<ForwardIterator, T, tail...>(++i); } the following class template template<typename T, T... args> struct params_to_array; template<typename T, T last> struct params_to_array<T, last> { static const std::size_t SIZE = 1; typedef std::array<T, SIZE> array_type; static const array_type params; private: void init_params() { array_type result; fill<typename array_type::iterator, T, head, tail...>(result.begin()); return result; } }; template<typename T, T head, T... tail> struct params_to_array<T, head, tail...> { static const std::size_t SIZE = params_to_array<T, tail...>::SIZE + 1; typedef std::array<T, SIZE> array_type; static const array_type params; private: void init_params() { array_type result; fill<typename array_type::iterator, T, last>(result.begin()); return result; } }; and initialized the static constants via template<typename T, T last> const typename param_to_array<T, last>::array_type param_to_array<T, last>::params = param_to_array<T, last>::init_params(); and template<typename T, T head, T... tail> const typename param_to_array<T, head, tail...>::array_type param_to_array<T, head, tail...>::params = param_to_array<T, head, tail...>::init_params(); Now the array param_to_array<int, 1, 3, 4>::params is a std::array<int, 3> and contains the values 1, 3 and 4. I think there must be a simpler way to achieve this behavior. Any suggestions? Edit: As Noah Roberts suggested in his answer I modified my program like the following: I wrote a new struct counting the elements in a parameter list: template<typename T, T... args> struct count; template<typename T, T head, T... tail> struct count<T, head, tail...> { static const std::size_t value = count<T, tail...>::value + 1; }; template<typename T, T last> stuct count<T, last> { static const std::size_t value = 1; }; and wrote the following function template<typename T, T... args> std::array<T, count<T, args...>::value> params_to_array() { std::array<T, count<T, args...>::value> result; fill<typename std::array<T, count<T, args...>::value>::iterator, T, args...>(result.begin()); return result; } Now I get with params_to_array<int, 10, 20, 30>() a std::array<int, 3> with the content 10, 20 and 30. Any further suggestions?

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Need a hand understanding this Java code please :-)

- by Brian

Hi all, Just wondering if anyone would be able to take a look at this code for implementing the quicksort algorithm and answer me a few questions, please :-) public class Run { /*************************************************************************** * Quicksort code from Sedgewick 7.1, 7.2. **************************************************************************/ public static void quicksort(double[] a) { //shuffle(a); // to guard against worst-case quicksort(a, 0, a.length - 1, 0); } static void quicksort(final double[] a, final int left, final int right, final int tdepth) { if (right <= left) return; final int i = partition(a, left, right); if ((tdepth < 4) && ((i - left) > 1000)) { final Thread t = new Thread() { public void run() { quicksort(a, left, i - 1, tdepth + 1); } }; t.start(); quicksort(a, i + 1, right, tdepth + 1); try { t.join(); } catch (InterruptedException e) { throw new RuntimeException("Cancelled", e); } } else { quicksort(a, left, i - 1, tdepth); quicksort(a, i + 1, right, tdepth); } } // partition a[left] to a[right], assumes left < right private static int partition(double[] a, int left, int right) { int i = left - 1; int j = right; while (true) { while (less(a[++i], a[right])) // find item on left to swap ; // a[right] acts as sentinel while (less(a[right], a[--j])) // find item on right to swap if (j == left) break; // don't go out-of-bounds if (i >= j) break; // check if pointers cross exch(a, i, j); // swap two elements into place } exch(a, i, right); // swap with partition element return i; } // is x < y ? private static boolean less(double x, double y) { return (x < y); } // exchange a[i] and a[j] private static void exch(double[] a, int i, int j) { double swap = a[i]; a[i] = a[j]; a[j] = swap; } // shuffle the array a[] private static void shuffle(double[] a) { int N = a.length; for (int i = 0; i < N; i++) { int r = i + (int) (Math.random() * (N - i)); // between i and N-1 exch(a, i, r); } } // test client public static void main(String[] args) { int N = 5000000; // Integer.parseInt(args[0]); // generate N random real numbers between 0 and 1 long start = System.currentTimeMillis(); double[] a = new double[N]; for (int i = 0; i < N; i++) a[i] = Math.random(); long stop = System.currentTimeMillis(); double elapsed = (stop - start) / 1000.0; System.out.println("Generating input: " + elapsed + " seconds"); // sort them start = System.currentTimeMillis(); quicksort(a); stop = System.currentTimeMillis(); elapsed = (stop - start) / 1000.0; System.out.println("Quicksort: " + elapsed + " seconds"); } } My questions are: What is the purpose of the variable tdepth? Is this considered a "proper" implementation of a parallel quicksort? I ask becuase it doesn't use implements Runnable or extends Thread... If it doesn't already, is it possible to modify this code to use multiple threads? By passing in the number of threads you want to use as a parameter, for example...? Many thanks, Brian

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Adjust parameters of serial port reading

- by clinisbut

Hello. I'm facing a particular issue that regards serial communication under win32. I'm communicating with a device can only accept frames when it is not already communicating. So I must find a valid frame and then inmediatelly send my request. I developed a class named Serial that handles basic operations on serial port (open, close, read, write) and then a Thread calls inside a loop read and write functions. Thread loop //Device is an object of class Serial while( device->isOpen() && !terminate ) { unsigned int readed = 0; unsigned long error = ERROR_SUCCESS; unsigned char* data = device->read( &readed, &error ); if( error==ERROR_SUCCESS ) { //If data received, deliver to upper level if( readed>0 ) { QByteArray output( (const char*)data, (signed int)readed ); emit dataArrived( output, readed ); } } else { //unrelated stuff } //Here I manage the writting issue //Only when nothing is received, and Upper layer wants to send a frame //(Upper layer only will mark as something to send when it detects a valid frame) if( readed==0 ) { out_lock.lock(); //If something to send... if( something_to_send > 0 ) { if( device->write( output_buffer, output_size, &error ) ) { //things... } } } } The Thread basically keeps reading, and when nothing is received, sees if somebody has signaled to send a frame (this means that a valid frame is just received). When this happens, it writes the frame through serial port. Here comes my problem. Inside the Serial::read() function: I use the overlapped way of reading: ::ClearCommError( handle, &dwErrors, &stat); if( stat.cbInQue ) { //If there's something to read, read it, please note the bytes to read parameter, here 1. bool ok = ::ReadFile( handle, buffer_in, 1, &bytes_read, &ov_reader ); if( !ok ) { DWORD _error = ::GetLastError(); if( _error == ERROR_IO_PENDING ) { DWORD result = ::WaitForMultipleObjects( 2, waiters, FALSE,INFINITE ); switch( result ) { //Eventshutdown case WAIT_OBJECT_0: /*code omitted*/break; case WAIT_OBJECT_0+1: ok = ::GetOverlappedResult( handle, &ov_reader, &bytes_read, true ); //check ok value omitted break; } } } } if( bytes_read>0 ) { *size = bytes_read; } Here starts my problem. When device sends me small frames (around 30 bytes) everything works fine, but when larger frames are sent, the code is not able to find any free time between frames causing the thread to never be able send any frame because readed is never 0. If I increase the number of bytes to read inside the read() function, lose the ability to detect when the device "listens": bool ok = ::ReadFile(handle, buffer_in, 50, &bytes_read, &ov_reader ); This happens because my app can receive the end of a frame together with the start of the next one. This behaviour is very common. In the other hand, if I change the INFINITE argument by a valid timeout in the WaitForMultipleObjects function, I lose data. So my question basically is... what I'm doing wrong? Why when reading 1 byte each time I don't find any free time to send my own frames? Thank you

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C++ copy-construct construct-and-assign question

- by Andy

Blockquote Here is an extract from item 56 of the book "C++ Gotchas": It's not uncommon to see a simple initialization of a Y object written any of three different ways, as if they were equivalent. Y a( 1066 ); Y b = Y(1066); Y c = 1066; In point of fact, all three of these initializations will probably result in the same object code being generated, but they're not equivalent. The initialization of a is known as a direct initialization, and it does precisely what one might expect. The initialization is accomplished through a direct invocation of Y::Y(int). The initializations of b and c are more complex. In fact, they're too complex. These are both copy initializations. In the case of the initialization of b, we're requesting the creation of an anonymous temporary of type Y, initialized with the value 1066. We then use this anonymous temporary as a parameter to the copy constructor for class Y to initialize b. Finally, we call the destructor for the anonymous temporary. To test this, I did a simple class with a data member (program attached at the end) and the results were surprising. It seems that for the case of b, the object was constructed by the copy constructor rather than as suggested in the book. Does anybody know if the language standard has changed or is this simply an optimisation feature of the compiler? I was using Visual Studio 2008. Code sample: #include <iostream> class Widget { std::string name; public: // Constructor Widget(std::string n) { name=n; std::cout << "Constructing Widget " << this->name << std::endl; } // Copy constructor Widget (const Widget& rhs) { std::cout << "Copy constructing Widget from " << rhs.name << std::endl; } // Assignment operator Widget& operator=(const Widget& rhs) { std::cout << "Assigning Widget from " << rhs.name << " to " << this->name << std::endl; return *this; } }; int main(void) { // construct Widget a("a"); // copy construct Widget b(a); // construct and assign Widget c("c"); c = a; // copy construct! Widget d = a; // construct! Widget e = "e"; // construct and assign Widget f = Widget("f"); return 0; } Output: Constructing Widget a Copy constructing Widget from a Constructing Widget c Assigning Widget from a to c Copy constructing Widget from a Constructing Widget e Constructing Widget f Copy constructing Widget from f I was most surprised by the results of constructing d and e.

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sherlock actionbar menu

- by user1647443

I am trying to setup a menu programatically and my method gets com.actionbarsherlock.view.Menu menu as a parameter. As I want to change the styling of the menu item I am trying to setup a SpannableString spannable and pass it to add. menu.add(0, MENU_ABOUT, 0, spannable); This is causing a crash only in ICS when I cick that menu item. Any ideas if I am missing something. Thanks Here is the code I am trying and it crashes when I run the app and select "About Application". FYI, I am using SpannableString because I want to add some styling and color to the menu item. The crash does NOT happen if I use a regular string, but then I cant do styling public boolean onCreateOptionsMenu(com.actionbarsherlock.view.Menu menu) { SpannableString spannable = new SpannableString("About Application"); menu.add(0, MENU_ABOUT, 0, spannable); return true; } Here is the stack trace: 09-05 02:25:32.849: E/AndroidRuntime(684): FATAL EXCEPTION: main 09-05 02:25:32.849: E/AndroidRuntime(684): java.lang.IllegalArgumentException: Invalid payload item type 09-05 02:25:32.849: E/AndroidRuntime(684): at android.util.EventLog.writeEvent(Native Method) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.app.Activity.onMenuItemSelected(Activity.java:2501) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.support.v4.app.FragmentActivity.onMenuItemSelected(FragmentActivity.java:351) 09-05 02:25:32.849: E/AndroidRuntime(684): at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:950) 09-05 02:25:32.849: E/AndroidRuntime(684): at com.android.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:735) 09-05 02:25:32.849: E/AndroidRuntime(684): at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:149) 09-05 02:25:32.849: E/AndroidRuntime(684): at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:874) 09-05 02:25:32.849: E/AndroidRuntime(684): at com.android.internal.view.menu.ListMenuPresenter.onItemClick(ListMenuPresenter.java:163) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.widget.AdapterView.performItemClick(AdapterView.java:292) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.widget.AbsListView.performItemClick(AbsListView.java:1058) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.widget.AbsListView$PerformClick.run(AbsListView.java:2514) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.widget.AbsListView.onTouchEvent(AbsListView.java:3180) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.view.View.dispatchTouchEvent(View.java:5541) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1951) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1712) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:1957) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1726) 09-05 02:25:32.849: E/AndroidRuntime(684): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1860) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.view.View.dispatchPointerEvent(View.java:5721) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:2890) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2466) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.view.ViewRootImpl.processInputEvents(ViewRootImpl.java:845) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2475) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.os.Handler.dispatchMessage(Handler.java:99) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.os.Looper.loop(Looper.java:137) 09-05 02:25:32.849: E/AndroidRuntime(684): at android.app.ActivityThread.main(ActivityThread.java:4424) 09-05 02:25:32.849: E/AndroidRuntime(684): at java.lang.reflect.Method.invokeNative(Native Method) 09-05 02:25:32.849: E/AndroidRuntime(684): at java.lang.reflect.Method.invoke(Method.java:511) 09-05 02:25:32.849: E/AndroidRuntime(684): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 09-05 02:25:32.849: E/AndroidRuntime(684): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 09-05 02:25:32.849: E/AndroidRuntime(684): at dalvik.system.NativeStart.main(Native Method) Thanks

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hosting simple python scripts in a container to handle concurrency, configuration, caching, etc.

- by Justin Grant

My first real-world Python project is to write a simple framework (or re-use/adapt an existing one) which can wrap small python scripts (which are used to gather custom data for a monitoring tool) with a "container" to handle boilerplate tasks like: fetching a script's configuration from a file (and keeping that info up to date if the file changes and handle decryption of sensitive config data) running multiple instances of the same script in different threads instead of spinning up a new process for each one expose an API for caching expensive data and storing persistent state from one script invocation to the next Today, script authors must handle the issues above, which usually means that most script authors don't handle them correctly, causing bugs and performance problems. In addition to avoiding bugs, we want a solution which lowers the bar to create and maintain scripts, especially given that many script authors may not be trained programmers. Below are examples of the API I've been thinking of, and which I'm looking to get your feedback about. A scripter would need to build a single method which takes (as input) the configuration that the script needs to do its job, and either returns a python object or calls a method to stream back data in chunks. Optionally, a scripter could supply methods to handle startup and/or shutdown tasks. HTTP-fetching script example (in pseudocode, omitting the actual data-fetching details to focus on the container's API): def run (config, context, cache) : results = http_library_call (config.url, config.http_method, config.username, config.password, ...) return { html : results.html, status_code : results.status, headers : results.response_headers } def init(config, context, cache) : config.max_threads = 20 # up to 20 URLs at one time (per process) config.max_processes = 3 # launch up to 3 concurrent processes config.keepalive = 1200 # keep process alive for 10 mins without another call config.process_recycle.requests = 1000 # restart the process every 1000 requests (to avoid leaks) config.kill_timeout = 600 # kill the process if any call lasts longer than 10 minutes Database-data fetching script example might look like this (in pseudocode): def run (config, context, cache) : expensive = context.cache["something_expensive"] for record in db_library_call (expensive, context.checkpoint, config.connection_string) : context.log (record, "logDate") # log all properties, optionally specify name of timestamp property last_date = record["logDate"] context.checkpoint = last_date # persistent checkpoint, used next time through def init(config, context, cache) : cache["something_expensive"] = get_expensive_thing() def shutdown(config, context, cache) : expensive = cache["something_expensive"] expensive.release_me() Is this API appropriately "pythonic", or are there things I should do to make this more natural to the Python scripter? (I'm more familiar with building C++/C#/Java APIs so I suspect I'm missing useful Python idioms.) Specific questions: is it natural to pass a "config" object into a method and ask the callee to set various configuration options? Or is there another preferred way to do this? when a callee needs to stream data back to its caller, is a method like context.log() (see above) appropriate, or should I be using yield instead? (yeild seems natural, but I worry it'd be over the head of most scripters) My approach requires scripts to define functions with predefined names (e.g. "run", "init", "shutdown"). Is this a good way to do it? If not, what other mechanism would be more natural? I'm passing the same config, context, cache parameters into every method. Would it be better to use a single "context" parameter instead? Would it be better to use global variables instead? Finally, are there existing libraries you'd recommend to make this kind of simple "script-running container" easier to write?

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NHibernate: How is identity Id updated when saving a transient instance?

- by bretddog

If I use session-per-transaction and call: session.SaveOrUpdate(entity) corrected: session.SaveOrUpdateCopy(entity) ..and entity is a transient instance with identity-Id=0. Shall the above line automatically update the Id of the entity, and make the instance persistent? Or should it do so on transaction.Commit? Or do I have to somehow code that explicitly? Obviously the Id of the database row (new, since transient) is autogenerated and saved as some number, but I'm talking about the actual parameter instance here. Which is the business logic instance. EDIT Mappings: public class StoreMap : ClassMap<Store> { public StoreMap() { Id(x => x.Id).GeneratedBy.Identity(); Map(x => x.Name); HasMany(x => x.Staff) // 1:m .Cascade.All(); HasManyToMany(x => x.Products) // m:m .Cascade.All() .Table("StoreProduct"); } } public class EmployeeMap : ClassMap<Employee> { public EmployeeMap() { Id(x => x.Id).GeneratedBy.Identity(); Map(x => x.FirstName); Map(x => x.LastName); References(x => x.Store); // m:1 } } public class ProductMap : ClassMap<Product> { public ProductMap() { Id(x => x.Id).GeneratedBy.Identity(); Map(x => x.Name).Length(20); Map(x => x.Price).CustomSqlType("decimal").Precision(9).Scale(2); HasManyToMany(x => x.StoresStockedIn) .Cascade.All() .Inverse() .Table("StoreProduct"); } } EDIT2 Class definitions: public class Store { public int Id { get; private set; } public string Name { get; set; } public IList<Product> Products { get; set; } public IList<Employee> Staff { get; set; } public Store() { Products = new List<Product>(); Staff = new List<Employee>(); } // AddProduct & AddEmployee is required. "NH needs you to set both sides before // it will save correctly" public void AddProduct(Product product) { product.StoresStockedIn.Add(this); Products.Add(product); } public void AddEmployee(Employee employee) { employee.Store = this; Staff.Add(employee); } } public class Employee { public int Id { get; private set; } public string FirstName { get; set; } public string LastName { get; set; } public Store Store { get; set; } } public class Product { public int Id { get; private set; } public string Name { get; set; } public decimal Price { get; set; } public IList<Store> StoresStockedIn { get; private set; } }

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Getting the constructor of an Interface Type through reflection?

- by Will Marcouiller

I have written a generic type: IDirectorySource<T> where T : IDirectoryEntry, which I'm using to manage Active Directory entries through my interfaces objects: IGroup, IOrganizationalUnit, IUser. So that I can write the following: IDirectorySource<IGroup> groups = new DirectorySource<IGroup>(); // Where IGroup implements `IDirectoryEntry`, of course.` foreach (IGroup g in groups.ToList()) { listView1.Items.Add(g.Name).SubItems.Add(g.Description); } From the IDirectorySource<T>.ToList() methods, I use reflection to find out the appropriate constructor for the type parameter T. However, since T is given an interface type, it cannot find any constructor at all! Of course, I have an internal class Group : IGroup which implements the IGroup interface. No matter how hard I have tried, I can't figure out how to get the constructor out of my interface through my implementing class. [DirectorySchemaAttribute("group")] public interface IGroup { } internal class Group : IGroup { internal Group(DirectoryEntry entry) { NativeEntry = entry; Domain = NativeEntry.Path; } // Implementing IGroup interface... } Within the ToList() method of my IDirectorySource<T> interface implementation, I look for the constructor of T as follows: internal class DirectorySource<T> : IDirectorySource<T> { // Implementing properties... // Methods implementations... public IList<T> ToList() { Type t = typeof(T) // Let's assume we're always working with the IGroup interface as T here to keep it simple. // So, my `DirectorySchema` property is already set to "group". // My `DirectorySearcher` is already instantiated here, as I do it within the DirectorySource<T> constructor. Searcher.Filter = string.Format("(&(objectClass={0}))", DirectorySchema) ConstructorInfo ctor = null; ParameterInfo[] params = null; // This is where I get stuck for now... Please see the helper method. GetConstructor(out ctor, out params, new Type() { DirectoryEntry }); SearchResultCollection results = null; try { results = Searcher.FindAll(); } catch (DirectoryServicesCOMException ex) { // Handling exception here... } foreach (SearchResult entry in results) entities.Add(ctor.Invoke(new object() { entry.GetDirectoryEntry() })); return entities; } } private void GetConstructor(out ConstructorInfo constructor, out ParameterInfo[] parameters, Type paramsTypes) { Type t = typeof(T); ConstructorInfo[] ctors = t.GetConstructors(BindingFlags.CreateInstance | BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.InvokeMethod); bool found = true; foreach (ContructorInfo c in ctors) { parameters = c.GetParameters(); if (parameters.GetLength(0) == paramsTypes.GetLength(0)) { for (int index = 0; index < parameters.GetLength(0); ++index) { if (!(parameters[index].GetType() is paramsTypes[index].GetType())) found = false; } if (found) { constructor = c; return; } } } // Processing constructor not found message here... } My problem is that T will always be an interface, so it never finds a constructor. Might somebody guide me to the right path to follow in this situation?

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Problem detaching entire object graph in GAE-J with JDO

- by tempy

I am trying to load the full object graph for User, which contains a collection of decks, which then contains a collection of cards, as such: User: @PersistenceCapable(detachable = "true") @Inheritance(strategy = InheritanceStrategy.SUBCLASS_TABLE) @FetchGroup(name = "decks", members = { @Persistent(name = "_Decks") }) public abstract class User { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) protected Key _ID; @Persistent protected String _UniqueIdentifier; @Persistent(mappedBy = "_Owner") @Element(dependent = "true") protected Set<Deck> _Decks; protected User() { } } Each Deck has a collection of Cards, as such: @PersistenceCapable(detachable = "true") @FetchGroup(name = "cards", members = { @Persistent(name = "_Cards") }) public class Deck { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key _ID; @Persistent String _Name; @Persistent(mappedBy = "_Parent") @Element(dependent = "true") private Set<Card> _Cards = new HashSet<Card>(); @Persistent private Set<String> _Tags = new HashSet<String>(); @Persistent private User _Owner; } And finally, each card: @PersistenceCapable public class Card { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private Key _ID; @Persistent private Text _Question; @Persistent private Text _Answer; @Persistent private Deck _Parent; } I am trying to retrieve and then detach the entire object graph. I can see in the debugger that it loads fine, but then when I get to detaching, I can't make anything beyond the User object load. (No Decks, no Cards). At first I tried without a transaction to simply "touch" all the fields on the attached object before detaching, but that didn't help. Then I tried adding everything to the default fetch group, but that just generated warnings about GAE not supporting joins. I tried setting the fetch plan's max fetch depth to -1, but that didn't do it. Finally, I tried using FetchGroups as you can see above, and then retrieving with the following code: PersistenceManager pm = _pmf.getPersistenceManager(); pm.setDetachAllOnCommit(true); pm.getFetchPlan().setGroup("decks"); pm.getFetchPlan().setGroup("cards"); Transaction tx = pm.currentTransaction(); Query query = null; try { tx.begin(); query = pm.newQuery(GoogleAccountsUser.class); //Subclass of User query.setFilter("_UniqueIdentifier == TheUser"); query.declareParameters("String TheUser"); List<User> results = (List<User>)query.execute(ID); //ID = Supplied parameter //TODO: Test for more than one result and throw if(results.size() == 0) { tx.commit(); return null; } else { User usr = (User)results.get(0); //usr = pm.detachCopy(usr); tx.commit(); return usr; } } finally { query.closeAll(); if (tx.isActive()) { tx.rollback(); } pm.close(); } This also doesn't work, and I'm running out of ideas...

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How to select table column names in a view and pass to controller in rails?

- by zachd1_618

So I am new to Rails, and OO programming in general. I have some grasp of the MVC architecture. My goal is to make a (nearly) completely dynamic plug-and-play plotting web server. I am fairly confused with params, forms, and select helpers. What I want to do is use Rails drop downs to basically pass parameters as strings to my controller, which will use the params to select certain column data from my database and plot it dynamically. I have the latter part of the task working, but I can't seem to pass values from my view to controller. For simplicity's sake, say my database schema looks like this: --------------Plot--------------- |____x____|____y1____|____y2____| | 1 | 1 | 1 | | 2 | 2 | 4 | | 3 | 3 | 9 | | 4 | 4 | 16 | | 5 | 5 | 25 | ... and in my Model, I have dynamic selector scopes that will let me select just certain columns of data: in Plot.rb class Plot < ActiveRecord::Base scope :select_var, lambda {|varname| select(varname)} scope :between_x, lambda {|x1,x2| where("x BETWEEN ? and ?","#{x1}","#{x2}")} So this way, I can call: irb>>@p1 = Plot.select_var(['x','y1']).between_x(1,3) and get in return a class where @p1.x and @p1.y1 are my only attributes, only for values between x=1 to x=4, which I dynamically plot. I want to start off in a view (plot/index), where I can dynamically select which variable names (table column names), and which rows from the database to fetch and plot. The problem is, most select helpers don't seem to work with columns in the database, only rows. So to select columns, I first get an array of column names that exist in my database with a function I wrote. Plots Controller def index d=Plot.first @tags = d.list_vars end So @tags = ['x','y1','y2'] Then in my plot/index.html.erb I try to use a drop down to select wich variables I send back to the controller. index.html.erb <%= select_tag( :variable, options_for_select(@plots.first.list_vars,:name,:multiple=>:true) )%> <%= button_to 'Plot now!', :controller =>"plots/plot_vars", :variable => params[:variable]%> Finally, in the controller again Plots controller ... def plot_vars @plot_data=Plot.select_vars([params[:variable]]) end The problem is everytime I try this (or one of a hundred variations thereof), the params[:variable] is nill. How can I use a drop down to pass a parameter with string variable names to the controller? Sorry its so long, I have been struggling with this for about a month now. :-( I think my biggest problem is that this setup doesn't really match the Rails architecture. I don't have "users" and "articles" as individual entities. I really have a data structure, not a data object. Trying to work with the structure in terms of data object speak is not necessarily the easiest thing to do I think. For background: My actual database has about 250 columns and a couple million rows, and they get changed and modified from time to time. I know I can make the database smarter, but its not worth it on my end. I work at a scientific institute where there are a ton of projects with databases just like this. Each one has a web developer that spends months setting up a web interface and their own janky plotting setups. I want to make this completely dynamic, as a plug-and-play solution so all you have to do is specify your database connection, and this rails setup will automatically show and plot which data you want in it. I am more of a sequential programmer and number cruncher, as are many people here. I think this project could be very helpful in the end, but its difficult to figure out for me right now.

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PHP Ajax not working

- by Kostis

I have 3 buttons on my page and depending on which one the user is clickingi want to run through ajax call a delete query in my database. When the user clicks on a button the javascript function seems to work but it doesn't run the query in php script. The html page: <?php session_start(); ?> <!DOCTYPE HTML> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-7"> <script> function myFunction(name) { var r=confirm("Are you sure? This action cannot be undone!"); if (r==true) { alert(name); // check if is getting in if statement and confirm the parameter's value var xmlhttp; if (str.length==0) { document.getElementById("clearMessage").innerHTML=""; return; } if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari xmlhttp=new XMLHttpRequest(); } else {// code for IE6, IE5 xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); } xmlhttp.onreadystatechange=function() { if (xmlhttp.readyState==4 && xmlhttp.status==200) { document.getElementById("clearMessage").innerHTML= responseText; } } xmlhttp.open("GET","clearDatabase.php?q="+name,true); xmlhttp.send(); } else alert('pff'); } </script> </head> <body> <div id="wrapper"> <div id="header"></div> <div id="main"> <?php if (session_is_registered("username")){ ?>  <input type="button" value="???a????s? pa?a??? µ???µ?t??" onclick="myFunction('messages')" /> <input type="button" value="???a????s? pa?a??? s??ed????" onclick="myFunction('conferences')" /> <input type="button" value="???a????s? push notifications" onclick="myFunction('notifications')" /> <div id="clearMessage"></div> <?php } else echo "Login first."; ?> </div> <div id="footer"></div> </div> </body> </html> and the php script: <?php if (isset($_GET["q"])) $q=$_GET["q"]; $host = "localhost"; $database = "dbname"; $user = "dbuser"; $pass = "dbpass"; $con = mysql_connect($host,$user,$pass) or die(mysql_error()); mysql_select_db($database,$con) or die(mysql_error()); if ($q=="messages") $query = "DELETE FROM push_message WHERE time_sent IS NOT NULL"; else if ($q=="conferences") $query = "DELETE FROM push_message WHERE time_sent IS NOT NULL"; else if ($q=="notifications") { $query = "DELETE FROM push_friend WHERE time_sent IS NOT NULL"; } $res = mysql_query($query,$con) or die(mysql_error()); if ($res) echo "success"; else echo "failed"; mysql_close($con); ?>

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How to reserve public API to internal usage in .NET?

- by mark

Dear ladies and sirs. Let me first present the case, which will explain my question. This is going to be a bit long, so I apologize in advance :-). I have objects and collections, which should support the Merge API (it is my custom API, the signature of which is immaterial for this question). This API must be internal, meaning only my framework should be allowed to invoke it. However, derived types should be able to override the basic implementation. The natural way to implement this pattern as I see it, is this: The Merge API is declared as part of some internal interface, let us say IMergeable. Because the interface is internal, derived types would not be able to implement it directly. Rather they must inherit it from a common base type. So, a common base type is introduced, which would implement the IMergeable interface explicitly, where the interface methods delegate to respective protected virtual methods, providing the default implementation. This way the API is only callable by my framework, but derived types may override the default implementation. The following code snippet demonstrates the concept: internal interface IMergeable { void Merge(object obj); } public class BaseFrameworkObject : IMergeable { protected virtual void Merge(object obj) { // The default implementation. } void IMergeable.Merge(object obj) { Merge(obj); } } public class SomeThirdPartyObject : BaseFrameworkObject { protected override void Merge(object obj) { // A derived type implementation. } } All is fine, provided a single common base type suffices, which is usually true for non collection types. The thing is that collections must be mergeable as well. Collections do not play nicely with the presented concept, because developers do not develop collections from the scratch. There are predefined implementations - observable, filtered, compound, read-only, remove-only, ordered, god-knows-what, ... They may be developed from scratch in-house, but once finished, they serve wide range of products and should never be tailored to some specific product. Which means, that either: they do not implement the IMergeable interface at all, because it is internal to some product the scope of the IMergeable interface is raised to public and the API becomes open and callable by all. Let us refer to these collections as standard collections. Anyway, the first option screws my framework, because now each possible standard collection type has to be paired with the respective framework version, augmenting the standard with the IMergeable interface implementation - this is so bad, I am not even considering it. The second option breaks the framework as well, because the IMergeable interface should be internal for a reason (whatever it is) and now this interface has to open to all. So what to do? My solution is this. make IMergeable public API, but add an extra parameter to the Merge method, I call it a security token. The interface implementation may check that the token references some internal object, which is never exposed to the outside. If this is the case, then the method was called from within the framework, otherwise - some outside API consumer attempted to invoke it and so the implementation can blow up with a SecurityException. Here is the modified code snippet demonstrating this concept: internal static class InternalApi { internal static readonly object Token = new object(); } public interface IMergeable { void Merge(object obj, object token); } public class BaseFrameworkObject : IMergeable { protected virtual void Merge(object obj) { // The default implementation. } public void Merge(object obj, object token) { if (!object.ReferenceEquals(token, InternalApi.Token)) { throw new SecurityException("bla bla bla"); } Merge(obj); } } public class SomeThirdPartyObject : BaseFrameworkObject { protected override void Merge(object obj) { // A derived type implementation. } } Of course, this is less explicit than having an internally scoped interface and the check is moved from the compile time to run time, yet this is the best I could come up with. Now, I have a gut feeling that there is a better way to solve the problem I have presented. I do not know, may be using some standard Code Access Security features? I have only vague understanding of it, but can LinkDemand attribute be somehow related to it? Anyway, I would like to hear other opinions. Thanks.

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linked list problem (with insert)

- by JohnWong

The problem appears with the insert function that I wrote. 3 conditions must work, I tested b/w 1 and 2, b/w 2 and 3 and as last element, they worked. But b/w 3 and 4, it did not work. It only display up to the new added record, and did not show the fourth element. Efficiency is not my concern here (not yet). Please guide me through this debug process. Thank you very much. #include<iostream> #include<string> using namespace std; struct List // we create a structure called List { string name; string tele; List *nextAddr; }; void populate(List *); void display(List *); void insert(List *); int main() { const int MAXINPUT = 3; char ans; List * data, * current, * point; // create two pointers data = new List; current = data; for (int i = 0; i < (MAXINPUT - 1); i++) { populate(current); current->nextAddr = new List; current = current->nextAddr; } // last record we want to do it sepeartely populate(current); current->nextAddr = NULL; cout << "The current list consists of the following data records: " << endl; display(data); // now ask whether user wants to insert new record or not cout << "Do you want to add a new record (Y/N)?"; cin >> ans; if (ans == 'Y' || ans == 'y') { /* To insert b/w first and second, use point as parameter between second and third uses point->nextAddr between third and fourth uses point->nextAddr->nextAddr and insert as last element, uses current instead */ point = data; insert(()); display(data); } return 0; } void populate(List *data) { cout << "Enter a name: "; cin >> data->name; cout << "Enter a phone number: "; cin >> data->tele; return; } void display(List *content) { while (content != NULL) { cout << content->name << " " << content->tele; content = content->nextAddr; cout << endl; // we skip to next line } return; } void insert(List *last) { List * temp = last->nextAddr; //save the next address to temp last->nextAddr = new List; // now modify the address pointed to new allocation last = last->nextAddr; populate(last); last->nextAddr = temp; // now link all three together, eg 1-NEW-2 return; }

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Azure - Part 4 - Table Storage Service in Windows Azure

- by Shaun

In Windows Azure platform there are 3 storage we can use to save our data on the cloud. They are the Table, Blob and Queue. Before the Chinese New Year Microsoft announced that Azure SDK 1.1 had been released and it supports a new type of storage – Drive, which allows us to operate NTFS files on the cloud. I will cover it in the coming few posts but now I would like to talk a bit about the Table Storage. Concept of Table Storage Service The most common development scenario is to retrieve, create, update and remove data from the data storage. In the normal way we communicate with database. When we attempt to move our application over to the cloud the most common requirement should be have a storage service. Windows Azure provides a in-build service that allow us to storage the structured data, which is called Windows Azure Table Storage Service. The data stored in the table service are like the collection of entities. And the entities are similar to rows or records in the tradtional database. An entity should had a partition key, a row key, a timestamp and set of properties. You can treat the partition key as a group name, the row key as a primary key and the timestamp as the identifer for solving the concurrency problem. Different with a table in a database, the table service does not enforce the schema for tables, which means you can have 2 entities in the same table with different property sets. The partition key is being used for the load balance of the Azure OS and the group entity transaction. As you know in the cloud you will never know which machine is hosting your application and your data. It could be moving based on the transaction weight and the number of the requests. If the Azure OS found that there are many requests connect to your Book entities with the partition key equals “Novel” it will move them to another idle machine to increase the performance. So when choosing the partition key for your entities you need to make sure they indecate the category or gourp information so that the Azure OS can perform the load balance as you wish. Consuming the Table Although the table service looks like a database, you cannot access it through the way you are using now, neither ADO.NET nor ODBC. The table service exposed itself by ADO.NET Data Service protocol, which allows you can consume it through the RESTful style by Http requests. The Azure SDK provides a sets of classes for us to connect it. There are 2 classes we might need: TableServiceContext and TableServiceEntity. The TableServiceContext inherited from the DataServiceContext, which represents the runtime context of the ADO.NET data service. It provides 4 methods mainly used by us: CreateQuery: It will create a IQueryable instance from a given type of entity. AddObject: Add the specified entity into Table Service. UpdateObject: Update an existing entity in the Table Service. DeleteObject: Delete an entity from the Table Service. Beofre you operate the table service you need to provide the valid account information. It’s something like the connect string of the database but with your account name and the account key when you created the storage service on the Windows Azure Development Portal. After getting the CloudStorageAccount you can create the CloudTableClient instance which provides a set of methods for using the table service. A very useful method would be CreateTableIfNotExist. It will create the table container for you if it’s not exsited. And then you can operate the eneities to that table through the methods I mentioned above. Let me explain a bit more through an exmaple. We always like code rather than sentence. Straightforward Accessing to the Table Here I would like to build a WCF service on the Windows Azure platform, and for now just one requirement: it would allow the client to create an account entity on the table service. The WCF service would have a method named Register and accept an instance of the account which the client wants to create. After perform some validation it will add the entity into the table service. So the first thing I should do is to create a Cloud Application on my VIstial Studio 2010 RC. (The Azure SDK 1.1 only supports VS2008 and VS2010 RC.) The solution should be like this below. Then I added a configuration items for the storage account through the Settings section under the cloud project. (Double click the Services file under Roles folder and navigate to the Setting section.) This setting will be used when to retrieve my storage account information. Since for now I just in the development phase I will select “UseDevelopmentStorage=true”. And then I navigated to the WebRole.cs file under my WCF project. If you have read my previous posts you would know that this file defines the process when the application start, and terminate on the cloud. What I need to do is to when the application start, set the configuration publisher to load my config file with the config name I specified. So the code would be like below. I removed the original service and contract created by the VS template and add my IAccountService contract and its implementation class - AccountService. And I add the service method Register with the parameters: email, password and it will return a boolean value to indicates the result which is very simple. At this moment if I press F5 the application will be established on my local development fabric and I can see my service runs well through the browser. Let’s implement the service method Rigister, add a new entity to the table service. As I said before the entities you want to store in the table service must have 3 properties: partition key, row key and timespan. You can create a class with these 3 properties. The Azure SDK provides us a base class for that named TableServiceEntity in Microsoft.WindowsAzure.StorageClient namespace. So what we need to do is more simply, create a class named Account and let it derived from the TableServiceEntity. And I need to add my own properties: Email, Password, DateCreated and DateDeleted. The DateDeleted is a nullable date time value to indecate whether this entity had been deleted and when. Do you notice that I missed something here? Yes it’s the partition key and row key I didn’t assigned. The TableServiceEntity base class defined 2 constructors one was a parameter-less constructor which will be used to fill values into the properties from the table service when retrieving data. The other was one with 2 parameters: partition key and row key. As I said below the partition key may affect the load balance and the row key must be unique so here I would like to use the email as the parition key and the email plus a Guid as the row key. OK now we finished the entity class we need to store onto the table service. The next step is to create a data access class for us to add it. Azure SDK gives us a base class for it named TableServiceContext as I mentioned below. So let’s create a class for operate the Account entities. The TableServiceContext need the storage account information for its constructor. It’s the combination of the storage service URI that we will create on Windows Azure platform, and the relevant account name and key. The TableServiceContext will use this information to find the related address and verify the account to operate the storage entities. Hence in my AccountDataContext class I need to override this constructor and pass the storage account into it. All entities will be saved in the table storage with one or many tables which we call them “table containers”. Before we operate an entity we need to make sure that the table container had been created on the storage. There’s a method we can use for that: CloudTableClient.CreateTableIfNotExist. So in the constructor I will perform it firstly to make sure all method will be invoked after the table had been created. Notice that I passed the storage account enpoint URI and the credentials to specify where my storage is located and who am I. Another advise is that, make your entity class name as the same as the table name when create the table. It will increase the performance when you operate it over the cloud especially querying. Since the Register WCF method will add a new account into the table service, here I will create a relevant method to add the account entity. Before implement, I should add a reference - System.Data.Services.Client to the project. This reference provides some common method within the ADO.NET Data Service which can be used in the Windows Azure Table Service. I will use its AddObject method to create my account entity. Since the table service are not fully implemented the ADO.NET Data Service, there are some methods in the System.Data.Services.Client that TableServiceContext doesn’t support, such as AddLinks, etc. Then I implemented the serivce method to add the account entity through the AccountDataContext. You can see in the service implmentation I load the storage account information through my configuration file and created the account table entity from the parameters. Then I created the AccountDataContext. If it’s my first time to invoke this method the constructor of the AccountDataContext will create a table container for me. Then I use Add method to add the account entity into the table. Next, let’s create a farely simple client application to test this service. I created a windows console application and added a service reference to my WCF service. The metadata information of the WCF service cannot be retrieved if it’s deployed on the Windows Azure even though the <serviceMetadata httpGetEnabled="true"/> had been set. If we need to get its metadata we can deploy it on the local development service and then changed the endpoint to the address which is on the cloud. In the client side app.config file I specified the endpoint to the local development fabric address. And the just implement the client to let me input an email and a password then invoke the WCF service to add my acocunt. Let’s run my application and see the result. Of course it should return TRUE to me. And in the local SQL Express I can see the data had been saved in the table. Summary In this post I explained more about the Windows Azure Table Storage Service. I also created a small application for demostration of how to connect and consume it through the ADO.NET Data Service Managed Library provided within the Azure SDK. I only show how to create an eneity in the storage service. In the next post I would like to explain about how to query the entities with conditions thruogh LINQ. I also would like to refactor my AccountDataContext class to make it dyamic for any kinds of entities. Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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Using a WPF ListView as a DataGrid

- by psheriff

Many people like to view data in a grid format of rows and columns. WPF did not come with a data grid control that automatically creates rows and columns for you based on the object you pass it. However, the WPF Toolkit can be downloaded from CodePlex.com that does contain a DataGrid control. This DataGrid gives you the ability to pass it a DataTable or a Collection class and it will automatically figure out the columns or properties and create all the columns for you and display the data.The DataGrid control also supports editing and many other features that you might not always need. This means that the DataGrid does take a little more time to render the data. If you want to just display data (see Figure 1) in a grid format, then a ListView works quite well for this task. Of course, you will need to create the columns for the ListView, but with just a little generic code, you can create the columns on the fly just like the WPF Toolkit’s DataGrid. Figure 1: A List of Data using a ListView A Simple ListView ControlThe XAML below is what you would use to create the ListView shown in Figure 1. However, the problem with using XAML is you have to pre-define the columns. You cannot re-use this ListView except for “Product” data. <ListView x:Name="lstData" ItemsSource="{Binding}"> <ListView.View> <GridView> <GridViewColumn Header="Product ID" Width="Auto" DisplayMemberBinding="{Binding Path=ProductId}" /> <GridViewColumn Header="Product Name" Width="Auto" DisplayMemberBinding="{Binding Path=ProductName}" /> <GridViewColumn Header="Price" Width="Auto" DisplayMemberBinding="{Binding Path=Price}" /> </GridView> </ListView.View></ListView> So, instead of creating the GridViewColumn’s in XAML, let’s learn to create them in code to create any amount of columns in a ListView. Create GridViewColumn’s From Data TableTo display multiple columns in a ListView control you need to set its View property to a GridView collection object. You add GridViewColumn objects to the GridView collection and assign the GridView to the View property. Each GridViewColumn object needs to be bound to a column or property name of the object that the ListView will be bound to. An ADO.NET DataTable object contains a collection of columns, and these columns have a ColumnName property which you use to bind to the GridViewColumn objects. Listing 1 shows a sample of reading and XML file into a DataSet object. After reading the data a GridView object is created. You can then loop through the DataTable columns collection and create a GridViewColumn object for each column in the DataTable. Notice the DisplayMemberBinding property is set to a new Binding to the ColumnName in the DataTable. C#private void FirstSample(){ // Read the data DataSet ds = new DataSet(); ds.ReadXml(GetCurrentDirectory() + @"\Xml\Product.xml"); // Create the GridView GridView gv = new GridView(); // Create the GridView Columns foreach (DataColumn item in ds.Tables[0].Columns) { GridViewColumn gvc = new GridViewColumn(); gvc.DisplayMemberBinding = new Binding(item.ColumnName); gvc.Header = item.ColumnName; gvc.Width = Double.NaN; gv.Columns.Add(gvc); } // Setup the GridView Columns lstData.View = gv; // Display the Data lstData.DataContext = ds.Tables[0];} VB.NETPrivate Sub FirstSample() ' Read the data Dim ds As New DataSet() ds.ReadXml(GetCurrentDirectory() & "\Xml\Product.xml") ' Create the GridView Dim gv As New GridView() ' Create the GridView Columns For Each item As DataColumn In ds.Tables(0).Columns Dim gvc As New GridViewColumn() gvc.DisplayMemberBinding = New Binding(item.ColumnName) gvc.Header = item.ColumnName gvc.Width = [Double].NaN gv.Columns.Add(gvc) Next ' Setup the GridView Columns lstData.View = gv ' Display the Data lstData.DataContext = ds.Tables(0)End SubListing 1: Loop through the DataTable columns collection to create GridViewColumn objects A Generic Method for Creating a GridViewInstead of having to write the code shown in Listing 1 for each ListView you wish to create, you can create a generic method that given any DataTable will return a GridView column collection. Listing 2 shows how you can simplify the code in Listing 1 by setting up a class called WPFListViewCommon and create a method called CreateGridViewColumns that returns your GridView. C#private void DataTableSample(){ // Read the data DataSet ds = new DataSet(); ds.ReadXml(GetCurrentDirectory() + @"\Xml\Product.xml"); // Setup the GridView Columns lstData.View = WPFListViewCommon.CreateGridViewColumns(ds.Tables[0]); lstData.DataContext = ds.Tables[0];} VB.NETPrivate Sub DataTableSample() ' Read the data Dim ds As New DataSet() ds.ReadXml(GetCurrentDirectory() & "\Xml\Product.xml") ' Setup the GridView Columns lstData.View = _ WPFListViewCommon.CreateGridViewColumns(ds.Tables(0)) lstData.DataContext = ds.Tables(0)End SubListing 2: Call a generic method to create GridViewColumns. The CreateGridViewColumns MethodThe CreateGridViewColumns method will take a DataTable as a parameter and create a GridView object with a GridViewColumn object in its collection for each column in your DataTable. C#public static GridView CreateGridViewColumns(DataTable dt){ // Create the GridView GridView gv = new GridView(); gv.AllowsColumnReorder = true; // Create the GridView Columns foreach (DataColumn item in dt.Columns) { GridViewColumn gvc = new GridViewColumn(); gvc.DisplayMemberBinding = new Binding(item.ColumnName); gvc.Header = item.ColumnName; gvc.Width = Double.NaN; gv.Columns.Add(gvc); } return gv;} VB.NETPublic Shared Function CreateGridViewColumns _ (ByVal dt As DataTable) As GridView ' Create the GridView Dim gv As New GridView() gv.AllowsColumnReorder = True ' Create the GridView Columns For Each item As DataColumn In dt.Columns Dim gvc As New GridViewColumn() gvc.DisplayMemberBinding = New Binding(item.ColumnName) gvc.Header = item.ColumnName gvc.Width = [Double].NaN gv.Columns.Add(gvc) Next Return gvEnd FunctionListing 3: The CreateGridViewColumns method takes a DataTable and creates GridViewColumn objects in a GridView. By separating this method out into a class you can call this method anytime you want to create a ListView with a collection of columns from a DataTable. SummaryIn this blog you learned how to create a ListView that acts like a DataGrid. You are able to use a DataTable as both the source of the data, and for creating the columns for the ListView. In the next blog entry you will learn how to use the same technique, but for Collection classes. NOTE: You can download the complete sample code (in both VB and C#) at my website. http://www.pdsa.com/downloads. Choose Tips & Tricks, then "WPF ListView as a DataGrid" from the drop-down. Good Luck with your Coding,Paul Sheriff ** SPECIAL OFFER FOR MY BLOG READERS **Visit http://www.pdsa.com/Event/Blog for a free eBook on "Fundamentals of N-Tier".

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Visual Studio 2013 Static Code Analysis in depth: What? When and How?

- by Hosam Kamel

In this post I'll illustrate in details the following points What is static code analysis? When to use? Supported platforms Supported Visual Studio versions How to use Run Code Analysis Manually Run Code Analysis Automatically Run Code Analysis while check-in source code to TFS version control (TFSVC) Run Code Analysis as part of Team Build Understand the Code Analysis results & learn how to fix them Create your custom rule set Q & A References What is static Rule analysis? Static Code Analysis feature of Visual Studio performs static code analysis on code to help developers identify potential design, globalization, interoperability, performance, security, and a lot of other categories of potential problems according to Microsoft's rules that mainly targets best practices in writing code, and there is a large set of those rules included with Visual Studio grouped into different categorized targeting specific coding issues like security, design, Interoperability, globalizations and others. Static here means analyzing the source code without executing it and this type of analysis can be performed through automated tools (like Visual Studio 2013 Code Analysis Tool) or manually through Code Review which already supported in Visual Studio 2012 and 2013 (check Using Code Review to Improve Quality video on Channel9) There is also Dynamic analysis which performed on executing programs using software testing techniques such as Code Coverage for example. When to use? Running Code analysis tool at regular intervals during your development process can enhance the quality of your software, examines your code for a set of common defects and violations is always a good programming practice. Adding that Code analysis can also find defects in your code that are difficult to discover through testing allowing you to achieve first level quality gate for you application during development phase before you release it to the testing team. Supported platforms .NET Framework, native (C and C++) Database applications. Support Visual Studio versions All version of Visual Studio starting Visual Studio 2013 (except Visual Studio Test Professional) check Feature comparisons Create and modify a custom rule set required Visual Studio Premium or Ultimate. How to use? Code Analysis can be run manually at any time from within the Visual Studio IDE, or even setup to automatically run as part of a Team Build or check-in policy for Team Foundation Server. Run Code Analysis Manually To run code analysis manually on a project, on the Analyze menu, click Run Code Analysis on your project or simply right click on the project name on the Solution Explorer choose Run Code Analysis from the context menu Run Code Analysis Automatically To run code analysis each time that you build a project, you select Enable Code Analysis on Build on the project's Property Page Run Code Analysis while check-in source code to TFS version control (TFSVC) Team Foundation Version Control (TFVC) provides a way for organizations to enforce practices that lead to better code and more efficient group development through Check-in policies which are rules that are set at the team project level and enforced on developer computers before code is allowed to be checked in. (This is available only if you're using Team Foundation Server) Require permissions on Team Foundation Server: you must have the Edit project-level information permission set to Allow typically your account must be part of Project Administrators, Project Collection Administrators, for more information about Team Foundation permissions check http://msdn.microsoft.com/en-us/library/ms252587(v=vs.120).aspx In Team Explorer, right-click the team project name, point to Team Project Settings, and then click Source Control. In the Source Control dialog box, select the Check-in Policy tab. Click Add to create a new check-in policy. Double-click the existing Code Analysis item in the Policy Type list to change the policy. Check or Uncheck the policy option based on the configurations you need to perform as illustrated below: Enforce check-in to only contain files that are part of current solution: code analysis can run only on files specified in solution and project configuration files. This policy guarantees that all code that is part of a solution is analyzed. Enforce C/C++ Code Analysis (/analyze): Requires that all C or C++ projects be built with the /analyze compiler option to run code analysis before they can be checked in. Enforce Code Analysis for Managed Code: Requires that all managed projects run code analysis and build before they can be checked in. Check Code analysis rule set reference on MSDN What is Rule Set? Rule Set is a group of code analysis rules like the example below where Microsoft.Design is the rule set name where "Do not declare static members on generic types" is the code analysis rule Once you configured the Analysis rule the policy will be enabled for all the team member in this project whenever a team member check-in any source code to the TFSVC the policy section will highlight the Code Analysis policy as below TFS is a very extensible platform so you can simply implement your own custom Code Analysis Check-in policy, check this link for more details http://msdn.microsoft.com/en-us/library/dd492668.aspx but you have to be aware also about compatibility between different TFS versions check http://msdn.microsoft.com/en-us/library/bb907157.aspx Run Code Analysis as part of Team Build With Team Foundation Build (TFBuild), you can create and manage build processes that automatically compile and test your applications, and perform other important functions. Code Analysis can be enabled in the Build Definition file by selecting the correct value for the build process parameter "Perform Code Analysis" Once configure, Kick-off your build definition to queue a new build, Code Analysis will run as part of build workflow and you will be able to see code analysis warning as part of build report Understand the Code Analysis results & learn how to fix them Now after you went through Code Analysis configurations and the different ways of running it, we will go through the Code Analysis result how to understand them and how to resolve them. Code Analysis window in Visual Studio will show all the analysis results based on the rule sets you configured in the project file properties, let's dig deep into what each result item contains: 1 Check ID The unique identifier for the rule. CheckId and Category are used for in-source suppression of a warning. 2 Title The title of warning message 3 Description A description of the problem or suggested fix 4 File Name File name and the line of code number which violate the code analysis rule set 5 Category The code analysis category for this error 6 Warning /Error Depend on how you configure it in the rule set the default is Warning level 7 Action Copy: copy the warning information to the clipboard Create Work Item: If you're connected to Team Foundation Server you can create a work item most probably you may create a Task or Bug and assign it for a developer to fix certain code analysis warning Suppress Message: There are times when you might decide not to fix a code analysis warning. You might decide that resolving the warning requires too much recoding in relation to the probability that the issue will arise in any real-world implementation of your code. Or you might believe that the analysis that is used in the warning is inappropriate for the particular context. You can suppress individual warnings so that they no longer appear in the Code Analysis window. Two options available: In Source inserts a SuppressMessage attribute in the source file above the method that generated the warning. This makes the suppression more discoverable. In Suppression File adds a SuppressMessage attribute to the GlobalSuppressions.cs file of the project. This can make the management of suppressions easier. Note that the SuppressMessage attribute added to GlobalSuppression.cs also targets the method that generated the warning. It does not suppress the warning globally. Visual Studio makes it very easy to fix Code analysis warning, all you have to do is clicking on the Check Id hyperlink if you are not aware how to fix the warring and you'll be directed to MSDN online or local copy based on the configuration you did while installing Visual Studio and you will find all the information about the warring including how to fix it. Create a Custom Code Analysis Rule Set The Microsoft standard rule sets provide groups of rules that are organized by function and depth. For example, the Microsoft Basic Design Guidelines Rules and the Microsoft Extended Design Guidelines Rules contain rules that focus on usability and maintainability issues, with added emphasis on naming rules in the Extended rule set, you can create and modify a custom rule set to meet specific project needs associated with code analysis. To create a custom rule set, you open one or more standard rule sets in the rule set editor. Create and modify a custom rule set required Visual Studio Premium or Ultimate. You can check How to: Create a Custom Rule Set on MSDN for more details http://msdn.microsoft.com/en-us/library/dd264974.aspx Q & A Visual Studio static code analysis vs. FxCop vs. StyleCpp http://www.excella.com/blog/stylecop-vs-fxcop-difference-between-code-analysis-tools/ Code Analysis for SharePoint Apps and SPDisposeCheck? This post lists some of the rule set you can run specifically for SharePoint applications and how to integrate SPDisposeCheck as well. Code Analysis for SQL Server Database Projects? This post illustrate how to run static code analysis on T-SQL through SSDT ReSharper 8 vs. Visual Studio 2013? This document lists some of the features that are provided by ReSharper 8 but are missing or not as fully implemented in Visual Studio 2013. References A Few Billion Lines of Code Later: Using Static Analysis to Find Bugs in the Real World http://cacm.acm.org/magazines/2010/2/69354-a-few-billion-lines-of-code-later/fulltext What is New in Code Analysis for Visual Studio 2013 http://blogs.msdn.com/b/visualstudioalm/archive/2013/07/03/what-is-new-in-code-analysis-for-visual-studio-2013.aspx Analyze the code quality of Windows Store apps using Visual Studio static code analysis http://msdn.microsoft.com/en-us/library/windows/apps/hh441471.aspx [Hands-on-lab] Using Code Analysis with Visual Studio 2012 to Improve Code Quality http://download.microsoft.com/download/A/9/2/A9253B14-5F23-4BC8-9C7E-F5199DB5F831/Using%20Code%20Analysis%20with%20Visual%20Studio%202012%20to%20Improve%20Code%20Quality.docx Originally posted at "Hosam Kamel| Developer & Platform Evangelist" http://blogs.msdn.com/hkamel

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Parallelism in .NET – Part 11, Divide and Conquer via Parallel.Invoke

- by Reed

Many algorithms are easily written to work via recursion. For example, most data-oriented tasks where a tree of data must be processed are much more easily handled by starting at the root, and recursively “walking” the tree. Some algorithms work this way on flat data structures, such as arrays, as well. This is a form of divide and conquer: an algorithm design which is based around breaking up a set of work recursively, “dividing” the total work in each recursive step, and “conquering” the work when the remaining work is small enough to be solved easily. Recursive algorithms, especially ones based on a form of divide and conquer, are often a very good candidate for parallelization. This is apparent from a common sense standpoint. Since we’re dividing up the total work in the algorithm, we have an obvious, built-in partitioning scheme. Once partitioned, the data can be worked upon independently, so there is good, clean isolation of data. Implementing this type of algorithm is fairly simple. The Parallel class in .NET 4 includes a method suited for this type of operation: Parallel.Invoke. This method works by taking any number of delegates defined as an Action, and operating them all in parallel. The method returns when every delegate has completed: Parallel.Invoke( () => { Console.WriteLine("Action 1 executing in thread {0}", Thread.CurrentThread.ManagedThreadId); }, () => { Console.WriteLine("Action 2 executing in thread {0}", Thread.CurrentThread.ManagedThreadId); }, () => { Console.WriteLine("Action 3 executing in thread {0}", Thread.CurrentThread.ManagedThreadId); } ); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Running this simple example demonstrates the ease of using this method. For example, on my system, I get three separate thread IDs when running the above code. By allowing any number of delegates to be executed directly, concurrently, the Parallel.Invoke method provides us an easy way to parallelize any algorithm based on divide and conquer. We can divide our work in each step, and execute each task in parallel, recursively. For example, suppose we wanted to implement our own quicksort routine. The quicksort algorithm can be designed based on divide and conquer. In each iteration, we pick a pivot point, and use that to partition the total array. We swap the elements around the pivot, then recursively sort the lists on each side of the pivot. For example, let’s look at this simple, sequential implementation of quicksort: public static void QuickSort<T>(T[] array) where T : IComparable<T> { QuickSortInternal(array, 0, array.Length - 1); } private static void QuickSortInternal<T>(T[] array, int left, int right) where T : IComparable<T> { if (left >= right) { return; } SwapElements(array, left, (left + right) / 2); int last = left; for (int current = left + 1; current <= right; ++current) { if (array[current].CompareTo(array[left]) < 0) { ++last; SwapElements(array, last, current); } } SwapElements(array, left, last); QuickSortInternal(array, left, last - 1); QuickSortInternal(array, last + 1, right); } static void SwapElements<T>(T[] array, int i, int j) { T temp = array[i]; array[i] = array[j]; array[j] = temp; } Here, we implement the quicksort algorithm in a very common, divide and conquer approach. Running this against the built-in Array.Sort routine shows that we get the exact same answers (although the framework’s sort routine is slightly faster). On my system, for example, I can use framework’s sort to sort ten million random doubles in about 7.3s, and this implementation takes about 9.3s on average. Looking at this routine, though, there is a clear opportunity to parallelize. At the end of QuickSortInternal, we recursively call into QuickSortInternal with each partition of the array after the pivot is chosen. This can be rewritten to use Parallel.Invoke by simply changing it to: // Code above is unchanged... SwapElements(array, left, last); Parallel.Invoke( () => QuickSortInternal(array, left, last - 1), () => QuickSortInternal(array, last + 1, right) ); } This routine will now run in parallel. When executing, we now see the CPU usage across all cores spike while it executes. However, there is a significant problem here – by parallelizing this routine, we took it from an execution time of 9.3s to an execution time of approximately 14 seconds! We’re using more resources as seen in the CPU usage, but the overall result is a dramatic slowdown in overall processing time. This occurs because parallelization adds overhead. Each time we split this array, we spawn two new tasks to parallelize this algorithm! This is far, far too many tasks for our cores to operate upon at a single time. In effect, we’re “over-parallelizing” this routine. This is a common problem when working with divide and conquer algorithms, and leads to an important observation: When parallelizing a recursive routine, take special care not to add more tasks than necessary to fully utilize your system. This can be done with a few different approaches, in this case. Typically, the way to handle this is to stop parallelizing the routine at a certain point, and revert back to the serial approach. Since the first few recursions will all still be parallelized, our “deeper” recursive tasks will be running in parallel, and can take full advantage of the machine. This also dramatically reduces the overhead added by parallelizing, since we’re only adding overhead for the first few recursive calls. There are two basic approaches we can take here. The first approach would be to look at the total work size, and if it’s smaller than a specific threshold, revert to our serial implementation. In this case, we could just check right-left, and if it’s under a threshold, call the methods directly instead of using Parallel.Invoke. The second approach is to track how “deep” in the “tree” we are currently at, and if we are below some number of levels, stop parallelizing. This approach is a more general-purpose approach, since it works on routines which parse trees as well as routines working off of a single array, but may not work as well if a poor partitioning strategy is chosen or the tree is not balanced evenly. This can be written very easily. If we pass a maxDepth parameter into our internal routine, we can restrict the amount of times we parallelize by changing the recursive call to: // Code above is unchanged... SwapElements(array, left, last); if (maxDepth < 1) { QuickSortInternal(array, left, last - 1, maxDepth); QuickSortInternal(array, last + 1, right, maxDepth); } else { --maxDepth; Parallel.Invoke( () => QuickSortInternal(array, left, last - 1, maxDepth), () => QuickSortInternal(array, last + 1, right, maxDepth)); } We no longer allow this to parallelize indefinitely – only to a specific depth, at which time we revert to a serial implementation. By starting the routine with a maxDepth equal to Environment.ProcessorCount, we can restrict the total amount of parallel operations significantly, but still provide adequate work for each processing core. With this final change, my timings are much better. On average, I get the following timings: Framework via Array.Sort: 7.3 seconds Serial Quicksort Implementation: 9.3 seconds Naive Parallel Implementation: 14 seconds Parallel Implementation Restricting Depth: 4.7 seconds Finally, we are now faster than the framework’s Array.Sort implementation.

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Create and Consume WCF service using Visual Studio 2010

- by sreejukg

In this article I am going to demonstrate how to create a WCF service, that can be hosted inside IIS and a windows application that consume the WCF service. To support service oriented architecture, Microsoft developed the programming model named Windows Communication Foundation (WCF). ASMX was the prior version from Microsoft, was completely based on XML and .Net framework continues to support ASMX web services in future versions also. While ASMX web services was the first step towards the service oriented architecture, Microsoft has made a big step forward by introducing WCF. An overview of planning for WCF can be found from this link http://msdn.microsoft.com/en-us/library/ff649584.aspx . The following are the important differences between WCF and ASMX from an asp.net developer point of view. 1. ASMX web services are easy to write, configure and consume 2. ASMX web services are only hosted in IIS 3. ASMX web services can only use http 4. WCF, can be hosted inside IIS, windows service, console application, WAS(Windows Process Activation Service) etc 5. WCF can be used with HTTP, TCP/IP, MSMQ and other protocols. The detailed difference between ASMX web service and WCF can be found here. http://msdn.microsoft.com/en-us/library/cc304771.aspx Though WCF is a bigger step for future, Visual Studio makes it simpler to create, publish and consume the WCF service. In this demonstration, I am going to create a service named SayHello that accepts 2 parameters such as name and language code. The service will return a hello to user name that corresponds to the language. So the proposed service usage is as follows. Caller: SayHello(“Sreeju”, “en”) -> return value -> Hello Sreeju Caller: SayHello(“???”, “ar”) -> return value -> ????? ??? Caller: SayHello(“Sreeju”, “es”) - > return value -> Hola Sreeju Note: calling an automated translation service is not the intention of this article. If you are interested, you can find bing translator API and can use in your application. http://www.microsofttranslator.com/dev/ So Let us start First I am going to create a Service Application that offer the SayHello Service. Open Visual Studio 2010, Go to File -> New Project, from your preferred language from the templates section select WCF, select WCF service application as the project type, give the project a name(I named it as HelloService), click ok so that visual studio will create the project for you. In this demonstration, I have used C# as the programming language. Visual studio will create the necessary files for you to start with. By default it will create a service with name Service1.svc and there will be an interface named IService.cs. The screenshot for the project in solution explorer is as follows Since I want to demonstrate how to create new service, I deleted Service1.Svc and IService1.cs files from the project by right click the file and select delete. Now in the project there is no service available, I am going to create one. From the solution explorer, right click the project, select Add -> New Item Add new item dialog will appear to you. Select WCF service from the list, give the name as HelloService.svc, and click on the Add button. Now Visual studio will create 2 files with name IHelloService.cs and HelloService.svc. These files are basically the service definition (IHelloService.cs) and the service implementation (HelloService.svc). Let us examine the IHelloService interface. The code state that IHelloService is the service definition and it provides an operation/method (similar to web method in ASMX web services) named DoWork(). Any WCF service will have a definition file as an Interface that defines the service. Let us see what is inside HelloService.svc The code illustrated is implementing the interface IHelloService. The code is self-explanatory; the HelloService class needs to implement all the methods defined in the Service Definition. Let me do the service as I require. Open IHelloService.cs in visual studio, and delete the DoWork() method and add a definition for SayHello(), do not forget to add OperationContract attribute to the method. The modified IHelloService.cs will look as follows Now implement the SayHello method in the HelloService.svc.cs file. Here I wrote the code for SayHello method as follows. I am done with the service. Now you can build and run the service by clicking f5 (or selecting start debugging from the debug menu). Visual studio will host the service in give you a client to test it. The screenshot is as follows. In the left pane, it shows the services available in the server and in right side you can invoke the service. To test the service sayHello, double click on it from the above window. It will ask you to enter the parameters and click on the invoke button. See a sample output below. Now I have done with the service. The next step is to write a service client. Creating a consumer application involves 2 steps. One generating the class and configuration file corresponds to the service. Create a project that utilizes the generated class and configuration file. First I am going to generate the class and configuration file. There is a great tool available with Visual Studio named svcutil.exe, this tool will create the necessary class and configuration files for you. Read the documentation for the svcutil.exe here http://msdn.microsoft.com/en-us/library/aa347733.aspx . Open Visual studio command prompt, you can find it under Start Menu -> All Programs -> Visual Studio 2010 -> Visual Studio Tools -> Visual Studio command prompt Make sure the service is in running state in visual studio. Note the url for the service(from the running window, you can right click and choose copy address). Now from the command prompt, enter the svcutil.exe command as follows. I have mentioned the url and the /d switch – for the directory to store the output files(In this case d:\temp). If you are using windows drive(in my case it is c: ) , make sure you open the command prompt with run as administrator option, otherwise you will get permission error(Only in windows 7 or windows vista). The tool has created 2 files, HelloService.cs and output.config. Now the next step is to create a new project and use the created files and consume the service. Let us do that now. I am going to add a console application to the current solution. Right click solution name in the solution explorer, right click, Add-> New Project Under Visual C#, select console application, give the project a name, I named it TestService Now navigate to d:\temp where I generated the files with the svcutil.exe. Rename output.config to app.config. Next step is to add both files (d:\temp\helloservice.cs and app.config) to the files. In the solution explorer, right click the project, Add -> Add existing item, browse to the d:\temp folder, select the 2 files as mentioned before, click on the add button. Now you need to add a reference to the System.ServiceModel to the project. From solution explorer, right click the references under testservice project, select Add reference. In the Add reference dialog, select the .Net tab, select System.ServiceModel, and click ok Now open program.cs by double clicking on it and add the code to consume the web service to the main method. The modified file looks as follows Right click the testservice project and set as startup project. Click f5 to run the project. See the sample output as follows Publishing WCF service under IIS is similar to publishing ASP.Net application. Publish the application to a folder using Visual studio publishing feature, create a virtual directory and create it as an application. Don’t forget to set the application pool to use ASP.Net version 4. One last thing you need to check is the app.config file you have added to the solution. See the element client under ServiceModel element. There is an endpoint element with address attribute that points to the published service URL. If you permanently host the service under IIS, you can simply change the address parameter to the corresponding one and your application will consume the service. You have seen how easily you can build/consume WCF service. If you need the solution in zipped format, please post your email below.

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CodePlex Daily Summary for Saturday, February 20, 2010

CodePlex Daily Summary for Saturday, February 20, 2010New ProjectsBerkeliumDotNet: BerkeliumDotNet is a .NET wrapper for the Berkelium library written in C++/CLI. Berkelium provides off-screen browser rendering via Google's Chromi...BoxBinary Descriptive WebCacheManager Framework: Allows you to take a simple, different, and more effective method of caching items in ASP.NET. The developer defines descriptive categories to deco...CHS Extranet: CHS Extranet Project, working with the RM Community to build the new RM Easylink type applicationDbModeller: Generates one class having properties with the basic C# types aimed to serve as a business object by using reflection from the passed objects insta...Dice.NET: Dice.NET is a simple dice roller for those cases where you just kinda forgot your real dices. It's very simple in setup/use.EBI App with the SQL Server CE and websync: EBI App with the SQL Server CE and SQL Server DEV with Merge Replication(Web Synchronization) ere we are trying to develop an application which yo...Family Tree Analyzer: This project with be a c# project which aims to allow users to import their GEDCOM files and produce various data analysis reports such as a list o...Go! Embedded Device Builder: Go! is a complete software engineering environment for the creation of embedded Linux devices. It enables you to engineer, design, develop, build, ...HiddenWordsReadingPlan: HiddenWordsReadingPlanHtml to OpenXml: A library to convert simple or advanced html to plain OpenXml document.Jeffrey Palermo's shared source: This project contains multiple samples with various snippets and projects from blog posts, user group talks, and conference sessions.Krypton Palette Selectors: A small C# control library that allows for simplified palette selection and management. It makes use of and relies on Component Factory's excellen...OCInject: A DI container on a diet. This is a basic DI container that lives in your project not an external assembly with support for auto generated delegat...Photo Organiser: A small utility to sort photos into a new file structure based on date held in their XMP or EXIF tags (YYYY/MM/DD/hhmmss.jpg). Developed in C# / WPF.QPAPrintLib: Print every document by its recommended programmReusable Library: A collection of reusable abstractions for enterprise application developer.Runtime Intelligence Data Visualizer: WPF application used to visualize Runtime Intelligence data using the Data Query Service from the Runtime Intelligence Endpoint Starter Kit.ScreenRec: ScreenRec is program for record your desktop and save to images or save one picture.Silverlight Internet Desktop Application Guidance: SLIDA (Silverlight Internet Desktop Applications) provides process guidance for developers creating Silverlight applications that run exclusively o...WSUS Web Administration: Web Application to remotely manage WSUSNew Releases7zbackup - PowerShell Script to Backup Files with 7zip: 7zBackup v. 1.7.0 Stable: Bug Solved : Test-Path-Writable fails on root of system drive on Windows 7. Therefore the function now accepts an optional parameter to specify if ...aqq: sec 1.02: Projeto SEC - Sistema economico Comercial - em Visual FoxPro 9.0 OpenSource ou seja gratis e com fontes, licença GNU/GPL para maiores informações e...ASP.NET MVC Attribute Based Route Mapper: Attribute Based Routes v0.2: ASP.NET MVC Attribute Based Route MapperBoxBinary Descriptive WebCacheManager Framework: Initial release: Initial assembly release for anyone wanting the files referenced in my talk at Umbraco's 5th Birthday London meetup 16/Feb/2010 The code is fairly...Build Version Increment Add-In Visual Studio: Build Version Increment v2.2 Beta: 2.2.10050.1548Added support for custom increment schemes via pluginsBuild Version Increment Add-In Visual Studio: BuildVersionIncrement v2.1: 2.1.10050.1458Fix: Localization issues Feature: Unmanaged C support Feature: Multi-Monitor support Feature: Global/Default settings Fix: De...CHS Extranet: Beta 2.3: Beta 2.3 Release Change Log: Fixed the update my details not updating the department/form Tried to fix the issue when the ampersand (&) is in t...Cover Creator: CoverCreator 1.2.2: Resolved BUG: If there is only one CD entry in freedb.org application do nothing. Instalation instructions Just unzip CoverCreator and run CoverCr...Employee Scheduler: Employee Scheduler 2.3: Extract the files to a directory and run Lab Hours.exe. Add an employee. Double click an employee to modify their times. Please contact me through ...EnOceanNet: EnOceanNet v1.11: Recompiled for .NET Framework 4 RCFree Silverlight & WPF Chart Control - Visifire: Visifire SL and WPF Charts 3.0.3 beta 4 Released: Hi, This release contains fix for the following bugs: * DataBinding was not working as expected with RIA services. * DataSeries visual wa...Html to OpenXml: HtmlToOpenXml 0.1 Beta: This is a beta version for testing purpose.Jeffrey Palermo's shared source: Web Forms front controller: This code goes along with my blog post about adding code that executes before your web form http://jeffreypalermo.com/blog/add-post-backs-to-mvc-nd...Krypton Palette Selectors: Initial Release: The initial release. Contains only the KryptonPaletteDropButton control.LaunchMeNot: LaunchMeNot 1.10: Lots has been added in this release. Feel free, however, to suggest features you'd like on the forums. Changes in LaunchMeNot 1.10 (19th February ...Magellan: Magellan 1.1.36820.4796 Stable: This is a stable release. It contains a fix for a bug whereby the content of zones in a shared layout couldn't use element bindings (due to name sc...Magellan: Magellan 1.1.36883.4800 Stable: This release includes a couple of major changes: A new Forms object model. See this page for details. Magellan objects are now part of the defau...MAISGestão: LayerDiagram: LayerDiagramMatrix3DEx: Matrix3DEx 1.0.2.0: Fixes the SwapHandedness method. This release includes factory methods for all common transformation matrices like rotation, scaling, translation, ...MDownloader: MDownloader-0.15.1.55880: Fixed bugs.NewLineReplacer: QPANewLineReplacer 1.1: Replace letter fast and easy in great textfilesOAuthLib: OAuthLib (1.5.0.1): Difference between 1.5.0.0 is just version number.OCInject: First Release: First ReleasePhoto Organiser: Installer alpha release: First release - contains known bugs, but works for the most part.Pinger: Pinger-1.0.0.0 Source: The Latest and First Source CodePinger: Pinger-1.0.0.2 Binary: Hi, This version can! work on Older versions of windows than 7 but i haven't test it! tnxPinger: Pinger-1.0.0.2 Source: Hi, It's the raw source!Reusable Library: v1.0: A collection of reusable abstractions for enterprise application developer.ScreenRec: Version 1: One version of this programSense/Net Enterprise Portal & ECMS: SenseNet 6.0 Beta 5: Sense/Net 6.0 Beta 5 Release Notes We are proud to finally present you Sense/Net 6.0 Beta 5, a major feature overhaul over beta43, and hopefully th...Silverlight Internet Desktop Application Guidance: v1: Project templates for Silverlight IDA and Silverlight Navigation IDA.SLAM! SharePoint List Association Manager: SLAM v1.3: The SharePoint List Association Manager is a platform for managing lists in SharePoint in a relational manner. The SLAM Hierarchy Extension works ...SQL Server PowerShell Extensions: 2.0.2 Production: Release 2.0.1 re-implements SQLPSX as PowersShell version 2.0 modules. SQLPSX consists of 8 modules with 133 advanced functions, 2 cmdlets and 7 sc...StoryQ: StoryQ 2.0.2 Library and Converter UI: Fixes: 16086 This release includes the following files: StoryQ.dll - the actual StoryQ library for you to reference StoryQ.xml - the xmldoc for ...Text to HTML: 0.4.0 beta: Cambios de la versión:Inclusión de los idiomas castellano, inglés y francés. Adición de una ventana de configuración. 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Java Logger API

- by Koppar

This is a more like a tip rather than technical write up and serves as a quick intro for newbies. The logger API helps to diagnose application level or JDK level issues at runtime. There are 7 levels which decide the detailing in logging (SEVERE, WARNING, INFO, CONFIG, FINE, FINER, FINEST). Its best to start with highest level and as we narrow down, use more detailed logging for a specific area. SEVERE is the highest and FINEST is the lowest. This may not make sense until we understand some jargon. The Logger class provides the ability to stream messages to an output stream in a format that can be controlled by the user. What this translates to is, I can create a logger with this simple invocation and use it add debug messages in my class: import java.util.logging.*; private static final Logger focusLog = Logger.getLogger("java.awt.focus.KeyboardFocusManager"); if (focusLog.isLoggable(Level.FINEST)) { focusLog.log(Level.FINEST, "Calling peer setCurrentFocusOwner}); LogManager acts like a book keeper and all the getLogger calls are forwarded to LogManager. The LogManager itself is a singleton class object which gets statically initialized on JVM start up. More on this later. If there is no existing logger with the given name, a new one is created. If there is one (and not yet GC’ed), then the existing Logger object is returned. By default, a root logger is created on JVM start up. All anonymous loggers are made as the children of the root logger. Named loggers have the hierarchy as per their name resolutions. Eg: java.awt.focus is the parent logger for java.awt.focus.KeyboardFocusManager etc. Before logging any message, the logger checks for the log level specified. If null is specified, the log level of the parent logger will be set. However, if the log level is off, no log messages would be written, irrespective of the parent’s log level. All the messages that are posted to the Logger are handled as a LogRecord object.i.e. FocusLog.log would create a new LogRecord object with the log level and message as its data members). The level of logging and thread number are also tracked. LogRecord is passed on to all the registered Handlers. Handler is basically a means to output the messages. The output may be redirected to either a log file or console or a network logging service. The Handler classes use the LogManager properties to set filters and formatters. During initialization or JVM start up, LogManager looks for logging.properties file in jre/lib and sets the properties if the file is provided. An alternate location for properties file can also be specified by setting java.util.logging.config.file system property. This can be set in Java Control Panel ? Java ? Runtime parameters as -Djava.util.logging.config.file = <mylogfile> or passed as a command line parameter java -Djava.util.logging.config.file = C:/Sunita/myLog The redirection of logging depends on what is specified rather registered as a handler with JVM in the properties file. java.util.logging.ConsoleHandler sends the output to system.err and java.util.logging.FileHandler sends the output to file. File name of the log file can also be specified. If you prefer XML format output, in the configuration file, set java.util.logging.FileHandler.formatter = java.util.logging.XMLFormatter and if you prefer simple text, set set java.util.logging.FileHandler.formatter =java.util.logging.SimpleFormatter Below is the default logging Configuration file: ############################################################ # Default Logging Configuration File # You can use a different file by specifying a filename # with the java.util.logging.config.file system property. # For example java -Djava.util.logging.config.file=myfile ############################################################ ############################################################ # Global properties ############################################################ # "handlers" specifies a comma separated list of log Handler # classes. These handlers will be installed during VM startup. # Note that these classes must be on the system classpath. # By default we only configure a ConsoleHandler, which will only # show messages at the INFO and above levels. handlers= java.util.logging.ConsoleHandler # To also add the FileHandler, use the following line instead. #handlers= java.util.logging.FileHandler, java.util.logging.ConsoleHandler # Default global logging level. # This specifies which kinds of events are logged across # all loggers. For any given facility this global level # can be overriden by a facility specific level # Note that the ConsoleHandler also has a separate level # setting to limit messages printed to the console. .level= INFO ############################################################ # Handler specific properties. # Describes specific configuration info for Handlers. ############################################################ # default file output is in user's home directory. java.util.logging.FileHandler.pattern = %h/java%u.log java.util.logging.FileHandler.limit = 50000 java.util.logging.FileHandler.count = 1 java.util.logging.FileHandler.formatter = java.util.logging.XMLFormatter # Limit the message that are printed on the console to INFO and above. java.util.logging.ConsoleHandler.level = INFO java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter ############################################################ # Facility specific properties. # Provides extra control for each logger. ############################################################ # For example, set the com.xyz.foo logger to only log SEVERE # messages: com.xyz.foo.level = SEVERE Since I primarily use this method to track focus issues, here is how I get detailed awt focus related logging. Just set the logger name to java.awt.focus.level=FINEST and change the default log level to FINEST. Below is a basic sample program. The sample programs are from http://www2.cs.uic.edu/~sloan/CLASSES/java/ and have been modified to illustrate the logging API. By changing the .level property in the logging.properties file, one can control the output written to the logs. To play around with the example, try changing the levels in the logging.properties file and notice the difference in messages going to the log file. Example --------KeyboardReader.java------------------------------------------------------------------------------------- import java.io.*; import java.util.*; import java.util.logging.*; public class KeyboardReader { private static final Logger mylog = Logger.getLogger("samples.input"); public static void main (String[] args) throws java.io.IOException { String s1; String s2; double num1, num2, product; // set up the buffered reader to read from the keyboard BufferedReader br = new BufferedReader (new InputStreamReader (System.in)); System.out.println ("Enter a line of input"); s1 = br.readLine(); if (mylog.isLoggable(Level.SEVERE)) { mylog.log (Level.SEVERE,"The line entered is " + s1); } if (mylog.isLoggable(Level.INFO)) { mylog.log (Level.INFO,"The line has " + s1.length() + " characters"); } if (mylog.isLoggable(Level.FINE)) { mylog.log (Level.FINE,"Breaking the line into tokens we get:"); } int numTokens = 0; StringTokenizer st = new StringTokenizer (s1); while (st.hasMoreTokens()) { s2 = st.nextToken(); numTokens++; if (mylog.isLoggable(Level.FINEST)) { mylog.log (Level.FINEST, " Token " + numTokens + " is: " + s2); } } } } ----------MyFileReader.java---------------------------------------------------------------------------------------- import java.io.*; import java.util.*; import java.util.logging.*; public class MyFileReader extends KeyboardReader { private static final Logger mylog = Logger.getLogger("samples.input.file"); public static void main (String[] args) throws java.io.IOException { String s1; String s2; // set up the buffered reader to read from the keyboard BufferedReader br = new BufferedReader (new FileReader ("MyFileReader.txt")); s1 = br.readLine(); if (mylog.isLoggable(Level.SEVERE)) { mylog.log (Level.SEVERE,"ATTN The line is " + s1); } if (mylog.isLoggable(Level.INFO)) { mylog.log (Level.INFO, "The line has " + s1.length() + " characters"); } if (mylog.isLoggable(Level.FINE)) { mylog.log (Level.FINE,"Breaking the line into tokens we get:"); } int numTokens = 0; StringTokenizer st = new StringTokenizer (s1); while (st.hasMoreTokens()) { s2 = st.nextToken(); numTokens++; if (mylog.isLoggable(Level.FINEST)) { mylog.log (Level.FINEST,"Breaking the line into tokens we get:"); mylog.log (Level.FINEST," Token " + numTokens + " is: " + s2); } } //end of while } // end of main } // end of class ----------MyFileReader.txt------------------------------------------------------------------------------------------ My first logging example -------logging.properties------------------------------------------------------------------------------------------- handlers= java.util.logging.ConsoleHandler, java.util.logging.FileHandler .level= FINEST java.util.logging.FileHandler.pattern = java%u.log java.util.logging.FileHandler.limit = 50000 java.util.logging.FileHandler.count = 1 java.util.logging.FileHandler.formatter = java.util.logging.SimpleFormatter java.util.logging.ConsoleHandler.level = FINEST java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter java.awt.focus.level=ALL ------Output log------------------------------------------------------------------------------------------- May 21, 2012 11:44:55 AM MyFileReader main SEVERE: ATTN The line is My first logging example May 21, 2012 11:44:55 AM MyFileReader main INFO: The line has 24 characters May 21, 2012 11:44:55 AM MyFileReader main FINE: Breaking the line into tokens we get: May 21, 2012 11:44:55 AM MyFileReader main FINEST: Breaking the line into tokens we get: May 21, 2012 11:44:55 AM MyFileReader main FINEST: Token 1 is: My May 21, 2012 11:44:55 AM MyFileReader main FINEST: Breaking the line into tokens we get: May 21, 2012 11:44:55 AM MyFileReader main FINEST: Token 2 is: first May 21, 2012 11:44:55 AM MyFileReader main FINEST: Breaking the line into tokens we get: May 21, 2012 11:44:55 AM MyFileReader main FINEST: Token 3 is: logging May 21, 2012 11:44:55 AM MyFileReader main FINEST: Breaking the line into tokens we get: May 21, 2012 11:44:55 AM MyFileReader main FINEST: Token 4 is: example Invocation command: "C:\Program Files (x86)\Java\jdk1.6.0_29\bin\java.exe" -Djava.util.logging.config.file=logging.properties MyFileReader References Further technical details are available here: http://docs.oracle.com/javase/1.4.2/docs/guide/util/logging/overview.html#1.0 http://docs.oracle.com/javase/1.4.2/docs/api/java/util/logging/package-summary.html http://www2.cs.uic.edu/~sloan/CLASSES/java/

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ASP.NET MVC ‘Extendable-hooks’ – ControllerActionInvoker class

- by nmarun

There’s a class ControllerActionInvoker in ASP.NET MVC. This can be used as one of an hook-points to allow customization of your application. Watching Brad Wilsons’ Advanced MP3 from MVC Conf inspired me to write about this class. What MSDN says: “Represents a class that is responsible for invoking the action methods of a controller.” Well if MSDN says it, I think I can instill a fair amount of confidence into what the class does. But just to get to the details, I also looked into the source code for MVC. Seems like the base class Controller is where an IActionInvoker is initialized: 1: protected virtual IActionInvoker CreateActionInvoker() { 2: return new ControllerActionInvoker(); 3: } In the ControllerActionInvoker (the O-O-B behavior), there are different ‘versions’ of InvokeActionMethod() method that actually call the action method in question and return an instance of type ActionResult. 1: protected virtual ActionResult InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary<string, object> parameters) { 2: object returnValue = actionDescriptor.Execute(controllerContext, parameters); 3: ActionResult result = CreateActionResult(controllerContext, actionDescriptor, returnValue); 4: return result; 5: } I guess that’s enough on the ‘behind-the-screens’ of this class. Let’s see how we can use this class to hook-up extensions. Say I have a requirement that the user should be able to get different renderings of the same output, like html, xml, json, csv and so on. The user will type-in the output format in the url and should the get result accordingly. For example: http://site.com/RenderAs/ – renders the default way (the razor view) http://site.com/RenderAs/xml http://site.com/RenderAs/csv … and so on where RenderAs is my controller. There are many ways of doing this and I’m using a custom ControllerActionInvoker class (even though this might not be the best way to accomplish this). For this, my one and only route in the Global.asax.cs is: 1: routes.MapRoute("RenderAsRoute", "RenderAs/{outputType}", 2: new {controller = "RenderAs", action = "Index", outputType = ""}); Here the controller name is ‘RenderAsController’ and the action that’ll get called (always) is the Index action. The outputType parameter will map to the type of output requested by the user (xml, csv…). I intend to display a list of food items for this example. 1: public class Item 2: { 3: public int Id { get; set; } 4: public string Name { get; set; } 5: public Cuisine Cuisine { get; set; } 6: } 7: 8: public class Cuisine 9: { 10: public int CuisineId { get; set; } 11: public string Name { get; set; } 12: } Coming to my ‘RenderAsController’ class. I generate an IList<Item> to represent my model. 1: private static IList<Item> GetItems() 2: { 3: Cuisine cuisine = new Cuisine { CuisineId = 1, Name = "Italian" }; 4: Item item = new Item { Id = 1, Name = "Lasagna", Cuisine = cuisine }; 5: IList<Item> items = new List<Item> { item }; 6: item = new Item {Id = 2, Name = "Pasta", Cuisine = cuisine}; 7: items.Add(item); 8: //... 9: return items; 10: } My action method looks like 1: public IList<Item> Index(string outputType) 2: { 3: return GetItems(); 4: } There are two things that stand out in this action method. The first and the most obvious one being that the return type is not of type ActionResult (or one of its derivatives). Instead I’m passing the type of the model itself (IList<Item> in this case). We’ll convert this to some type of an ActionResult in our custom controller action invoker class later. The second thing (a little subtle) is that I’m not doing anything with the outputType value that is passed on to this action method. This value will be in the RouteData dictionary and we’ll use this in our custom invoker class as well. It’s time to hook up our invoker class. First, I’ll override the Initialize() method of my RenderAsController class. 1: protected override void Initialize(RequestContext requestContext) 2: { 3: base.Initialize(requestContext); 4: string outputType = string.Empty; 5: 6: // read the outputType from the RouteData dictionary 7: if (requestContext.RouteData.Values["outputType"] != null) 8: { 9: outputType = requestContext.RouteData.Values["outputType"].ToString(); 10: } 11: 12: // my custom invoker class 13: ActionInvoker = new ContentRendererActionInvoker(outputType); 14: } Coming to the main part of the discussion – the ContentRendererActionInvoker class: 1: public class ContentRendererActionInvoker : ControllerActionInvoker 2: { 3: private readonly string _outputType; 4: 5: public ContentRendererActionInvoker(string outputType) 6: { 7: _outputType = outputType.ToLower(); 8: } 9: //... 10: } So the outputType value that was read from the RouteData, which was passed in from the url, is being set here in a private field. Moving to the crux of this article, I now override the CreateActionResult method. 1: protected override ActionResult CreateActionResult(ControllerContext controllerContext, ActionDescriptor actionDescriptor, object actionReturnValue) 2: { 3: if (actionReturnValue == null) 4: return new EmptyResult(); 5: 6: ActionResult result = actionReturnValue as ActionResult; 7: if (result != null) 8: return result; 9: 10: // This is where the magic happens 11: // Depending on the value in the _outputType field, 12: // return an appropriate ActionResult 13: switch (_outputType) 14: { 15: case "json": 16: { 17: JavaScriptSerializer serializer = new JavaScriptSerializer(); 18: string json = serializer.Serialize(actionReturnValue); 19: return new ContentResult { Content = json, ContentType = "application/json" }; 20: } 21: case "xml": 22: { 23: XmlSerializer serializer = new XmlSerializer(actionReturnValue.GetType()); 24: using (StringWriter writer = new StringWriter()) 25: { 26: serializer.Serialize(writer, actionReturnValue); 27: return new ContentResult { Content = writer.ToString(), ContentType = "text/xml" }; 28: } 29: } 30: case "csv": 31: controllerContext.HttpContext.Response.AddHeader("Content-Disposition", "attachment; filename=items.csv"); 32: return new ContentResult 33: { 34: Content = ToCsv(actionReturnValue as IList<Item>), 35: ContentType = "application/ms-excel" 36: }; 37: case "pdf": 38: string filePath = controllerContext.HttpContext.Server.MapPath("~/items.pdf"); 39: controllerContext.HttpContext.Response.AddHeader("content-disposition", 40: "attachment; filename=items.pdf"); 41: ToPdf(actionReturnValue as IList<Item>, filePath); 42: return new FileContentResult(StreamFile(filePath), "application/pdf"); 43: 44: default: 45: controllerContext.Controller.ViewData.Model = actionReturnValue; 46: return new ViewResult 47: { 48: TempData = controllerContext.Controller.TempData, 49: ViewData = controllerContext.Controller.ViewData 50: }; 51: } 52: } A big method there! The hook I was talking about kinda above actually is here. This is where different kinds / formats of output get returned based on the output type requested in the url. When the _outputType is not set (string.Empty as set in the Global.asax.cs file), the razor view gets rendered (lines 45-50). This is the default behavior in most MVC applications where-in a view (webform/razor) gets rendered on the browser. As you see here, this gets returned as a ViewResult. But then, for an outputType of json/xml/csv, a ContentResult gets returned, while for pdf, a FileContentResult is returned. Here are how the different kinds of output look like: This is how we can leverage this feature of ASP.NET MVC to developer a better application. I’ve used the iTextSharp library to convert to a pdf format. Mike gives quite a bit of detail regarding this library here. You can download the sample code here. (You’ll get an option to download once you open the link). Verdict: Hot chocolate: $3; Reebok shoes: $50; Your first car: $3000; Being able to extend a web application: Priceless.

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Calling Web Service Functions Asynchronously from a Web Page

- by SGWellens

Over on the Asp.Net forums where I moderate, a user had a problem calling a Web Service from a web page asynchronously. I tried his code on my machine and was able to reproduce the problem. I was able to solve his problem, but only after taking the long scenic route through some of the more perplexing nuances of Web Services and Proxies. Here is the fascinating story of that journey. Start with a simple Web Service public class Service1 : System.Web.Services.WebService { [WebMethod] public string HelloWorld() { // sleep 10 seconds System.Threading.Thread.Sleep(10 * 1000); return "Hello World"; } } The 10 second delay is added to make calling an asynchronous function more apparent. If you don't call the function asynchronously, it takes about 10 seconds for the page to be rendered back to the client. If the call is made from a Windows Forms application, the application freezes for about 10 seconds. Add the web service to a web site. Right-click the project and select "Add Web Reference…" Next, create a web page to call the Web Service. Note: An asp.net web page that calls an 'Async' method must have the Async property set to true in the page's header: <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" Async='true' %> Here is the code to create the Web Service proxy and connect the event handler. Shrewdly, we make the proxy object a member of the Page class so it remains instantiated between the various events. public partial class _Default : System.Web.UI.Page { localhost.Service1 MyService; // web service proxy // ---- Page_Load --------------------------------- protected void Page_Load(object sender, EventArgs e) { MyService = new localhost.Service1(); MyService.HelloWorldCompleted += EventHandler; } Here is the code to invoke the web service and handle the event: // ---- Async and EventHandler (delayed render) -------------------------- protected void ButtonHelloWorldAsync_Click(object sender, EventArgs e) { // blocks ODS("Pre HelloWorldAsync..."); MyService.HelloWorldAsync(); ODS("Post HelloWorldAsync"); } public void EventHandler(object sender, localhost.HelloWorldCompletedEventArgs e) { ODS("EventHandler"); ODS(" " + e.Result); } // ---- ODS ------------------------------------------------ // // Helper function: Output Debug String public static void ODS(string Msg) { String Out = String.Format("{0} {1}", DateTime.Now.ToString("hh:mm:ss.ff"), Msg); System.Diagnostics.Debug.WriteLine(Out); } I added a utility function I use a lot: ODS (Output Debug String). Rather than include the library it is part of, I included it in the source file to keep this example simple. Fire up the project, open up a debug output window, press the button and we get this in the debug output window: 11:29:37.94 Pre HelloWorldAsync... 11:29:37.94 Post HelloWorldAsync 11:29:48.94 EventHandler 11:29:48.94 Hello World Sweet. The asynchronous call was made and returned immediately. About 10 seconds later, the event handler fires and we get the result. Perfect….right? Not so fast cowboy. Watch the browser during the call: What the heck? The page is waiting for 10 seconds. Even though the asynchronous call returned immediately, Asp.Net is waiting for the event to fire before it renders the page. This is NOT what we wanted. I experimented with several techniques to work around this issue. Some may erroneously describe my behavior as 'hacking' but, since no ingesting of Twinkies was involved, I do not believe hacking is the appropriate term. If you examine the proxy that was automatically created, you will find a synchronous call to HelloWorld along with an additional set of methods to make asynchronous calls. I tried the other asynchronous method supplied in the proxy: // ---- Begin and CallBack ---------------------------------- protected void ButtonBeginHelloWorld_Click(object sender, EventArgs e) { ODS("Pre BeginHelloWorld..."); MyService.BeginHelloWorld(AsyncCallback, null); ODS("Post BeginHelloWorld"); } public void AsyncCallback(IAsyncResult ar) { String Result = MyService.EndHelloWorld(ar); ODS("AsyncCallback"); ODS(" " + Result); } The BeginHelloWorld function in the proxy requires a callback function as a parameter. I tested it and the debug output window looked like this: 04:40:58.57 Pre BeginHelloWorld... 04:40:58.57 Post BeginHelloWorld 04:41:08.58 AsyncCallback 04:41:08.58 Hello World It works the same as before except for one critical difference: The page rendered immediately after the function call. I was worried the page object would be disposed after rendering the page but the system was smart enough to keep the page object in memory to handle the callback. Both techniques have a use: Delayed Render: Say you want to verify a credit card, look up shipping costs and confirm if an item is in stock. You could have three web service calls running in parallel and not render the page until all were finished. Nice. You can send information back to the client as part of the rendered page when all the services are finished. Immediate Render: Say you just want to start a service running and return to the client. You can do that too. However, the page gets sent to the client before the service has finished running so you will not be able to update parts of the page when the service finishes running. Summary: YourFunctionAsync() and an EventHandler will not render the page until the handler fires. BeginYourFunction() and a CallBack function will render the page as soon as possible. I found all this to be quite interesting and did a lot of searching and researching for documentation on this subject….but there isn't a lot out there. The biggest clues are the parameters that can be sent to the WSDL.exe program: http://msdn.microsoft.com/en-us/library/7h3ystb6(VS.100).aspx Two parameters are oldAsync and newAsync. OldAsync will create the Begin/End functions; newAsync will create the Async/Event functions. Caveat: I haven't tried this but it was stated in this article. I'll leave confirming this as an exercise for the student J. Included Code: I'm including the complete test project I created to verify the findings. The project was created with VS 2008 SP1. There is a solution file with 3 projects, the 3 projects are: Web Service Asp.Net Application Windows Forms Application To decide which program runs, you right-click a project and select "Set as Startup Project". I created and played with the Windows Forms application to see if it would reveal any secrets. I found that in the Windows Forms application, the generated proxy did NOT include the Begin/Callback functions. Those functions are only generated for Asp.Net pages. Probably for the reasons discussed earlier. Maybe those Microsoft boys and girls know what they are doing. I hope someone finds this useful. Steve Wellens

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Entity Framework version 1- Brief Synopsis and Tips – Part 1

- by Rohit Gupta

To Do Eager loading use Projections (for e.g. from c in context.Contacts select c, c.Addresses) or use Include Query Builder Methods (Include(“Addresses”)) If there is multi-level hierarchical Data then to eager load all the relationships use Include Query Builder methods like customers.Include("Order.OrderDetail") to include Order and OrderDetail collections or use customers.Include("Order.OrderDetail.Location") to include all Order, OrderDetail and location collections with a single include statement =========================================================================== If the query uses Joins then Include() Query Builder method will be ignored, use Nested Queries instead If the query does projections then Include() Query Builder method will be ignored Use Address.ContactReference.Load() OR Contact.Addresses.Load() if you need to Deferred Load Specific Entity – This will result in extra round trips to the database ObjectQuery<> cannot return anonymous types... it will return a ObjectQuery<DBDataRecord> Only Include method can be added to Linq Query Methods Any Linq Query method can be added to Query Builder methods. If you need to append a Query Builder Method (other than Include) after a LINQ method then cast the IQueryable<Contact> to ObjectQuery<Contact> and then append the Query Builder method to it =========================================================================== Query Builder methods are Select, Where, Include Methods which use Entity SQL as parameters e.g. "it.StartDate, it.EndDate" When Query Builder methods do projection then they return ObjectQuery<DBDataRecord>, thus to iterate over this collection use contact.Item[“Name”].ToString() When Linq To Entities methods do projection, they return collection of anonymous types --- thus the collection is strongly typed and supports Intellisense EF Object Context can track changes only on Entities, not on Anonymous types. If you use a Defining Query for a EntitySet then the EntitySet becomes readonly since a Defining Query is the same as a View (which is treated as a ReadOnly by default). However if you want to use this EntitySet for insert/update/deletes then we need to map stored procs (as created in the DB) to the insert/update/delete functions of the Entity in the Designer You can use either Execute method or ToList() method to bind data to datasources/bindingsources If you use the Execute Method then remember that you can traverse through the ObjectResult<> collection (returned by Execute) only ONCE. In WPF use ObservableCollection to bind to data sources , for keeping track of changes and letting EF send updates to the DB automatically. Use Extension Methods to add logic to Entities. For e.g. create extension methods for the EntityObject class. Create a method in ObjectContext Partial class and pass the entity as a parameter, then call this method as desired from within each entity. ================================================================ DefiningQueries and Stored Procedures: For Custom Entities, one can use DefiningQuery or Stored Procedures. Thus the Custom Entity Collection will be populated using the DefiningQuery (of the EntitySet) or the Sproc. If you use Sproc to populate the EntityCollection then the query execution is immediate and this execution happens on the Server side and any filters applied will be applied in the Client App. If we use a DefiningQuery then these queries are composable, meaning the filters (if applied to the entityset) will all be sent together as a single query to the DB, returning only filtered results. If the sproc returns results that cannot be mapped to existing entity, then we first create the Entity/EntitySet in the CSDL using Designer, then create a dummy Entity/EntitySet using XML in the SSDL. When creating a EntitySet in the SSDL for this dummy entity, use a TSQL that does not return any results, but does return the relevant columns e.g. select ContactID, FirstName, LastName from dbo.Contact where 1=2 Also insure that the Entity created in the SSDL uses the SQL DataTypes and not .NET DataTypes. If you are unable to open the EDMX file in the designer then note the Errors ... they will give precise info on what is wrong. The Thrid option is to simply create a Native Query in the SSDL using <Function Name="PaymentsforContact" IsComposable="false"> <CommandText>SELECT ActivityId, Activity AS ActivityName, ImagePath, Category FROM dbo.Activities </CommandText></FuncTion> Then map this Function to a existing Entity. This is a quick way to get a custom Entity which is regular Entity with renamed columns or additional columns (which are computed columns). The disadvantage to using this is that It will return all the rows from the Defining query and any filter (if defined) will be applied only at the Client side (after getting all the rows from DB). If you you DefiningQuery instead then we can use that as a Composable Query. The Fourth option (for mapping a READ stored proc results to a non-existent Entity) is to create a View in the Database which returns all the fields that the sproc also returns, then update the Model so that the model contains this View as a Entity. Then map the Read Sproc to this View Entity. The other option would be to simply create the View and remove the sproc altogether. ================================================================ To Execute a SProc that does not return a entity, use a EntityCommand to execute that proc. You cannot call a sproc FunctionImport that does not return Entities From Code, the only way is to use SSDL function calls using EntityCommand. This changes with EntityFramework Version 4 where you can return Scalar Types, Complex Types, Entities or NonQuery ================================================================ UDF when created as a Function in SSDL, we need to set the Name & IsComposable properties for the Function element. IsComposable is always false for Sprocs, for UDF's set this to true. You cannot call UDF "Function" from within code since you cannot import a UDF Function into the CSDL Model (with Version 1 of EF). only stored procedures can be imported and then mapped to a entity ================================================================ Entity Framework requires properties that are involved in association mappings to be mapped in all of the function mappings for the entity (Insert, Update and Delete). Because Payment has an association to Reservation... hence we need to pass both the paymentId and reservationId to the Delete sproc even though just the paymentId is the PK on the Payment Table. ================================================================ When mapping insert, update and delete procs to a Entity, insure that all the three or none are mapped. Further if you have a base class and derived class in the CSDL, then you must map (ins, upd, del) sprocs to all parent and child entities in the inheritance relationship. Note that this limitation that base and derived entity methods must all must be mapped does not apply when you are mapping Read Stored Procedures.... ================================================================ You can write stored procedures SQL directly into the SSDL by creating a Function element in the SSDL and then once created, you can map this Function to a CSDL Entity directly in the designer during Function Import ================================================================ You can do Entity Splitting such that One Entity maps to multiple tables in the DB. For e.g. the Customer Entity currently derives from Contact Entity...in addition it also references the ContactPersonalInfo Entity. One can copy all properties from the ContactPersonalInfo Entity into the Customer Entity and then Delete the CustomerPersonalInfo entity, finall one needs to map the copied properties to the ContactPersonalInfo Table in Table Mapping (by adding another table (ContactPersonalInfo) to the Table Mapping... this is called Entity Splitting. Thus now when you insert a Customer record, it will automatically create SQL to insert records into the Contact, Customers and ContactPersonalInfo tables even though you have a Single Entity called Customer in the CSDL =================================================================== There is Table by Type Inheritance where another EDM Entity can derive from another EDM entity and absorb the inherted entities properties, for example in the Break Away Geek Adventures EDM, the Customer entity derives (inherits) from the Contact Entity and absorbs all the properties of Contact entity. Thus when you create a Customer Entity in Code and then call context.SaveChanges the Object Context will first create the TSQL to insert into the Contact Table followed by a TSQL to insert into the Customer table =================================================================== Then there is the Table per Hierarchy Inheritance..... where different types are created based on a condition (similar applying a condition to filter a Entity to contain filtered records)... the diference being that the filter condition populates a new Entity Type (derived from the base Entity). In the BreakAway sample the example is Lodging Entity which is a Abstract Entity and Then Resort and NonResort Entities which derive from Lodging Entity and records are filtered based on the value of the Resort Boolean field =================================================================== Then there is Table per Concrete Type Hierarchy where we create a concrete Entity for each table in the database. In the BreakAway sample there is a entity for the Reservation table and another Entity for the OldReservation table even though both the table contain the same number of fields. The OldReservation Entity can then inherit from the Reservation Entity and configure the OldReservation Entity to remove all Scalar Properties from the Entity (since it inherits the properties from Reservation and filters based on ReservationDate field) =================================================================== Complex Types (Complex Properties) Entities in EF can also contain Complex Properties (in addition to Scalar Properties) and these Complex Properties reference a ComplexType (not a EntityType) DropdownList, ListBox, RadioButtonList, CheckboxList, Bulletedlist are examples of List server controls (not data bound controls) these controls cannot use Complex properties during databinding, they need Scalar Properties. So if a Entity contains Complex properties and you need to bind those to list server controls then use projections to return Scalar properties and bind them to the control (the disadvantage is that projected collections are not tracked by the Object Context and hence cannot persist changes to the projected collections bound to controls) ObjectDataSource and EntityDataSource do account for Complex properties and one can bind entities with Complex Properties to Data Source controls and they will be tracked for changes... with no additional plumbing needed to persist changes to these collections bound to controls So DataBound controls like GridView, FormView need to use EntityDataSource or ObjectDataSource as a datasource for entities that contain Complex properties so that changes to the datasource done using the GridView can be persisted to the DB (enabling the controls for updates)....if you cannot use the EntityDataSource you need to flatten the ComplexType Properties using projections With EF Version 4 ComplexTypes are supported by the Designer and can add/remove/compose Complex Types directly using the Designer =================================================================== Conditional Mapping ... is like Table per Hierarchy Inheritance where Entities inherit from a base class and then used conditions to populate the EntitySet (called conditional Mapping). Conditional Mapping has limitations since you can only use =, is null and IS NOT NULL Conditions to do conditional mapping. If you need more operators for filtering/mapping conditionally then use QueryView(or possibly Defining Query) to create a readonly entity. QueryView are readonly by default... the EntitySet created by the QueryView is enabled for change tracking by the ObjectContext, however the ObjectContext cannot create insert/update/delete TSQL statements for these Entities when SaveChanges is called since it is QueryView. One way to get around this limitation is to map stored procedures for the insert/update/delete operations in the Designer. =================================================================== Difference between QueryView and Defining Query : QueryView is defined in the (MSL) Mapping File/section of the EDM XML, whereas the DefiningQuery is defined in the store schema (SSDL). QueryView is written using Entity SQL and is this database agnostic and can be used against any database/Data Layer. DefiningQuery is written using Database Lanaguage i.e. TSQL or PSQL thus you have more control =================================================================== Performance: Lazy loading is deferred loading done automatically. lazy loading is supported with EF version4 and is on by default. If you need to turn it off then use context.ContextOptions.lazyLoadingEnabled = false To improve Performance consider PreCompiling the ObjectQuery using the CompiledQuery.Compile method

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A Nondeterministic Engine written in VB.NET 2010

- by neil chen

When I'm reading SICP (Structure and Interpretation of Computer Programs) recently, I'm very interested in the concept of an "Nondeterministic Algorithm". According to wikipedia: In computer science, a nondeterministic algorithm is an algorithm with one or more choice points where multiple different continuations are possible, without any specification of which one will be taken. For example, here is an puzzle came from the SICP: Baker, Cooper, Fletcher, Miller, and Smith live on different floors of an apartment housethat contains only five floors. Baker does not live on the top floor. Cooper does not live onthe bottom floor. Fletcher does not live on either the top or the bottom floor. Miller lives ona higher floor than does Cooper. Smith does not live on a floor adjacent to Fletcher's.Fletcher does not live on a floor adjacent to Cooper's. Where does everyone live? After reading this I decided to build a simple nondeterministic calculation engine with .NET. The rough idea is that we can use an iterator to track each set of possible values of the parameters, and then we implement some logic inside the engine to automate the statemachine, so that we can try one combination of the values, then test it, and then move to the next. We also used a backtracking algorithm to go back when we are running out of choices at some point. Following is the core code of the engine itself: Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--Public Class NonDeterministicEngine Private _paramDict As New List(Of Tuple(Of String, IEnumerator)) 'Private _predicateDict As New List(Of Tuple(Of Func(Of Object, Boolean), IEnumerable(Of String))) Private _predicateDict As New List(Of Tuple(Of Object, IList(Of String))) Public Sub AddParam(ByVal name As String, ByVal values As IEnumerable) _paramDict.Add(New Tuple(Of String, IEnumerator)(name, values.GetEnumerator())) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(1, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(2, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Object, Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(3, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Object, Object, Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(4, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Object, Object, Object, Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(5, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Object, Object, Object, Object, Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(6, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Object, Object, Object, Object, Object, Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(7, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Public Sub AddRequire(ByVal predicate As Func(Of Object, Object, Object, Object, Object, Object, Object, Object, Boolean), ByVal paramNames As IList(Of String)) CheckParamCount(8, paramNames) _predicateDict.Add(New Tuple(Of Object, IList(Of String))(predicate, paramNames)) End Sub Sub CheckParamCount(ByVal count As Integer, ByVal paramNames As IList(Of String)) If paramNames.Count <> count Then Throw New Exception("Parameter count does not match.") End If End Sub Public Property IterationOver As Boolean Private _firstTime As Boolean = True Public ReadOnly Property Current As Dictionary(Of String, Object) Get If IterationOver Then Return Nothing Else Dim _nextResult = New Dictionary(Of String, Object) For Each item In _paramDict Dim iter = item.Item2 _nextResult.Add(item.Item1, iter.Current) Next Return _nextResult End If End Get End Property Function MoveNext() As Boolean If IterationOver Then Return False End If If _firstTime Then For Each item In _paramDict Dim iter = item.Item2 iter.MoveNext() Next _firstTime = False Return True Else Dim canMoveNext = False Dim iterIndex = _paramDict.Count - 1 canMoveNext = _paramDict(iterIndex).Item2.MoveNext If canMoveNext Then Return True End If Do While Not canMoveNext iterIndex = iterIndex - 1 If iterIndex = -1 Then Return False IterationOver = True End If canMoveNext = _paramDict(iterIndex).Item2.MoveNext If canMoveNext Then For i = iterIndex + 1 To _paramDict.Count - 1 Dim iter = _paramDict(i).Item2 iter.Reset() iter.MoveNext() Next Return True End If Loop End If End Function Function GetNextResult() As Dictionary(Of String, Object) While MoveNext() Dim result = Current If Satisfy(result) Then Return result End If End While Return Nothing End Function Function Satisfy(ByVal result As Dictionary(Of String, Object)) As Boolean For Each item In _predicateDict Dim pred = item.Item1 Select Case item.Item2.Count Case 1 Dim p1 = DirectCast(pred, Func(Of Object, Boolean)) Dim v1 = result(item.Item2(0)) If Not p1(v1) Then Return False End If Case 2 Dim p2 = DirectCast(pred, Func(Of Object, Object, Boolean)) Dim v1 = result(item.Item2(0)) Dim v2 = result(item.Item2(1)) If Not p2(v1, v2) Then Return False End If Case 3 Dim p3 = DirectCast(pred, Func(Of Object, Object, Object, Boolean)) Dim v1 = result(item.Item2(0)) Dim v2 = result(item.Item2(1)) Dim v3 = result(item.Item2(2)) If Not p3(v1, v2, v3) Then Return False End If Case 4 Dim p4 = DirectCast(pred, Func(Of Object, Object, Object, Object, Boolean)) Dim v1 = result(item.Item2(0)) Dim v2 = result(item.Item2(1)) Dim v3 = result(item.Item2(2)) Dim v4 = result(item.Item2(3)) If Not p4(v1, v2, v3, v4) Then Return False End If Case 5 Dim p5 = DirectCast(pred, Func(Of Object, Object, Object, Object, Object, Boolean)) Dim v1 = result(item.Item2(0)) Dim v2 = result(item.Item2(1)) Dim v3 = result(item.Item2(2)) Dim v4 = result(item.Item2(3)) Dim v5 = result(item.Item2(4)) If Not p5(v1, v2, v3, v4, v5) Then Return False End If Case 6 Dim p6 = DirectCast(pred, Func(Of Object, Object, Object, Object, Object, Object, Boolean)) Dim v1 = result(item.Item2(0)) Dim v2 = result(item.Item2(1)) Dim v3 = result(item.Item2(2)) Dim v4 = result(item.Item2(3)) Dim v5 = result(item.Item2(4)) Dim v6 = result(item.Item2(5)) If Not p6(v1, v2, v3, v4, v5, v6) Then Return False End If Case 7 Dim p7 = DirectCast(pred, Func(Of Object, Object, Object, Object, Object, Object, Object, Boolean)) Dim v1 = result(item.Item2(0)) Dim v2 = result(item.Item2(1)) Dim v3 = result(item.Item2(2)) Dim v4 = result(item.Item2(3)) Dim v5 = result(item.Item2(4)) Dim v6 = result(item.Item2(5)) Dim v7 = result(item.Item2(6)) If Not p7(v1, v2, v3, v4, v5, v6, v7) Then Return False End If Case 8 Dim p8 = DirectCast(pred, Func(Of Object, Object, Object, Object, Object, Object, Object, Object, Boolean)) Dim v1 = result(item.Item2(0)) Dim v2 = result(item.Item2(1)) Dim v3 = result(item.Item2(2)) Dim v4 = result(item.Item2(3)) Dim v5 = result(item.Item2(4)) Dim v6 = result(item.Item2(5)) Dim v7 = result(item.Item2(6)) Dim v8 = result(item.Item2(7)) If Not p8(v1, v2, v3, v4, v5, v6, v7, v8) Then Return False End If Case Else Throw New NotSupportedException End Select Next Return True End FunctionEnd Class And now we can use the engine to solve the problem we mentioned above: Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--Sub Test2() Dim engine = New NonDeterministicEngine() engine.AddParam("baker", {1, 2, 3, 4, 5}) engine.AddParam("cooper", {1, 2, 3, 4, 5}) engine.AddParam("fletcher", {1, 2, 3, 4, 5}) engine.AddParam("miller", {1, 2, 3, 4, 5}) engine.AddParam("smith", {1, 2, 3, 4, 5}) engine.AddRequire(Function(baker) As Boolean Return baker <> 5 End Function, {"baker"}) engine.AddRequire(Function(cooper) As Boolean Return cooper <> 1 End Function, {"cooper"}) engine.AddRequire(Function(fletcher) As Boolean Return fletcher <> 1 And fletcher <> 5 End Function, {"fletcher"}) engine.AddRequire(Function(miller, cooper) As Boolean 'Return miller = cooper + 1 Return miller > cooper End Function, {"miller", "cooper"}) engine.AddRequire(Function(smith, fletcher) As Boolean Return smith <> fletcher + 1 And smith <> fletcher - 1 End Function, {"smith", "fletcher"}) engine.AddRequire(Function(fletcher, cooper) As Boolean Return fletcher <> cooper + 1 And fletcher <> cooper - 1 End Function, {"fletcher", "cooper"}) engine.AddRequire(Function(a, b, c, d, e) As Boolean Return a <> b And a <> c And a <> d And a <> e And b <> c And b <> d And b <> e And c <> d And c <> e And d <> e End Function, {"baker", "cooper", "fletcher", "miller", "smith"}) Dim result = engine.GetNextResult() While Not result Is Nothing Console.WriteLine(String.Format("baker: {0}, cooper: {1}, fletcher: {2}, miller: {3}, smith: {4}", result("baker"), result("cooper"), result("fletcher"), result("miller"), result("smith"))) result = engine.GetNextResult() End While Console.WriteLine("Calculation ended.")End Sub Also, this engine can solve the classic 8 queens puzzle and find out all 92 results for me. Code highlighting produced by Actipro CodeHighlighter (freeware)http://www.CodeHighlighter.com/--Sub Test3() ' The 8-Queens problem. Dim engine = New NonDeterministicEngine() ' Let's assume that a - h represents the queens in row 1 to 8, then we just need to find out the column number for each of them. engine.AddParam("a", {1, 2, 3, 4, 5, 6, 7, 8}) engine.AddParam("b", {1, 2, 3, 4, 5, 6, 7, 8}) engine.AddParam("c", {1, 2, 3, 4, 5, 6, 7, 8}) engine.AddParam("d", {1, 2, 3, 4, 5, 6, 7, 8}) engine.AddParam("e", {1, 2, 3, 4, 5, 6, 7, 8}) engine.AddParam("f", {1, 2, 3, 4, 5, 6, 7, 8}) engine.AddParam("g", {1, 2, 3, 4, 5, 6, 7, 8}) engine.AddParam("h", {1, 2, 3, 4, 5, 6, 7, 8}) Dim NotInTheSameDiagonalLine = Function(cols As IList) As Boolean For i = 0 To cols.Count - 2 For j = i + 1 To cols.Count - 1 If j - i = Math.Abs(cols(j) - cols(i)) Then Return False End If Next Next Return True End Function engine.AddRequire(Function(a, b, c, d, e, f, g, h) As Boolean Return a <> b AndAlso a <> c AndAlso a <> d AndAlso a <> e AndAlso a <> f AndAlso a <> g AndAlso a <> h AndAlso b <> c AndAlso b <> d AndAlso b <> e AndAlso b <> f AndAlso b <> g AndAlso b <> h AndAlso c <> d AndAlso c <> e AndAlso c <> f AndAlso c <> g AndAlso c <> h AndAlso d <> e AndAlso d <> f AndAlso d <> g AndAlso d <> h AndAlso e <> f AndAlso e <> g AndAlso e <> h AndAlso f <> g AndAlso f <> h AndAlso g <> h AndAlso NotInTheSameDiagonalLine({a, b, c, d, e, f, g, h}) End Function, {"a", "b", "c", "d", "e", "f", "g", "h"}) Dim result = engine.GetNextResult() While Not result Is Nothing Console.WriteLine("(1,{0}), (2,{1}), (3,{2}), (4,{3}), (5,{4}), (6,{5}), (7,{6}), (8,{7})", result("a"), result("b"), result("c"), result("d"), result("e"), result("f"), result("g"), result("h")) result = engine.GetNextResult() End While Console.WriteLine("Calculation ended.")End Sub (Chinese version of the post: http://www.cnblogs.com/RChen/archive/2010/05/17/1737587.html) Cheers,

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