single instance - Page 210

JS best practice for member functions

- by MickMalone1983

I'm writing a little mobile games library, and I'm not sure the best practice for declaring member functions of instantiated function objects. For instance, I might create a simple object with one property, and a method to print it: function Foo(id){ this.id = id; this.print = function(){ console.log(this.id); }; }; However, a function which does not need access to 'private' members of the function does not need to be declared in the function at all. I could equally have written: function print(){ console.log(this.id); }; function Foo(id){ this.id = id; this.print = print; }; When the function is invoked through an instance of Foo, the instance becomes the context for this, so the output is the same in either case. I'm not entirely sure how memory is allocated with JS, and I can't find anything that I can understand about something this specific, but it seems to me that with the first example all members of Foo, including the print function, are duplicated each time it is instantiated - but with the second, it just gets a pointer to one, pre-declared function, which would save any more memory having to be allocated as more instances of Foo are created. Am I correct, and if I am, is there any memory/performance benefit to doing this?

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

- by James Michael Hare

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

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PTLQueue : a scalable bounded-capacity MPMC queue

- by Dave

Title: Fast concurrent MPMC queue -- I've used the following concurrent queue algorithm enough that it warrants a blog entry. I'll sketch out the design of a fast and scalable multiple-producer multiple-consumer (MPSC) concurrent queue called PTLQueue. The queue has bounded capacity and is implemented via a circular array. Bounded capacity can be a useful property if there's a mismatch between producer rates and consumer rates where an unbounded queue might otherwise result in excessive memory consumption by virtue of the container nodes that -- in some queue implementations -- are used to hold values. A bounded-capacity queue can provide flow control between components. Beware, however, that bounded collections can also result in resource deadlock if abused. The put() and take() operators are partial and wait for the collection to become non-full or non-empty, respectively. Put() and take() do not allocate memory, and are not vulnerable to the ABA pathologies. The PTLQueue algorithm can be implemented equally well in C/C++ and Java. Partial operators are often more convenient than total methods. In many use cases if the preconditions aren't met, there's nothing else useful the thread can do, so it may as well wait via a partial method. An exception is in the case of work-stealing queues where a thief might scan a set of queues from which it could potentially steal. Total methods return ASAP with a success-failure indication. (It's tempting to describe a queue or API as blocking or non-blocking instead of partial or total, but non-blocking is already an overloaded concurrency term. Perhaps waiting/non-waiting or patient/impatient might be better terms). It's also trivial to construct partial operators by busy-waiting via total operators, but such constructs may be less efficient than an operator explicitly and intentionally designed to wait. A PTLQueue instance contains an array of slots, where each slot has volatile Turn and MailBox fields. The array has power-of-two length allowing mod/div operations to be replaced by masking. We assume sensible padding and alignment to reduce the impact of false sharing. (On x86 I recommend 128-byte alignment and padding because of the adjacent-sector prefetch facility). Each queue also has PutCursor and TakeCursor cursor variables, each of which should be sequestered as the sole occupant of a cache line or sector. You can opt to use 64-bit integers if concerned about wrap-around aliasing in the cursor variables. Put(null) is considered illegal, but the caller or implementation can easily check for and convert null to a distinguished non-null proxy value if null happens to be a value you'd like to pass. Take() will accordingly convert the proxy value back to null. An advantage of PTLQueue is that you can use atomic fetch-and-increment for the partial methods. We initialize each slot at index I with (Turn=I, MailBox=null). Both cursors are initially 0. All shared variables are considered "volatile" and atomics such as CAS and AtomicFetchAndIncrement are presumed to have bidirectional fence semantics. Finally T is the templated type. I've sketched out a total tryTake() method below that allows the caller to poll the queue. tryPut() has an analogous construction. Zebra stripping : alternating row colors for nice-looking code listings. See also google code "prettify" : https://code.google.com/p/google-code-prettify/ Prettify is a javascript module that yields the HTML/CSS/JS equivalent of pretty-print. -- pre:nth-child(odd) { background-color:#ff0000; } pre:nth-child(even) { background-color:#0000ff; } border-left: 11px solid #ccc; margin: 1.7em 0 1.7em 0.3em; background-color:#BFB; font-size:12px; line-height:65%; " // PTLQueue : Put(v) : // producer : partial method - waits as necessary assert v != null assert Mask = 1 && (Mask & (Mask+1)) == 0 // Document invariants // doorway step // Obtain a sequence number -- ticket // As a practical concern the ticket value is temporally unique // The ticket also identifies and selects a slot auto tkt = AtomicFetchIncrement (&PutCursor, 1) slot * s = &Slots[tkt & Mask] // waiting phase : // wait for slot's generation to match the tkt value assigned to this put() invocation. // The "generation" is implicitly encoded as the upper bits in the cursor // above those used to specify the index : tkt div (Mask+1) // The generation serves as an epoch number to identify a cohort of threads // accessing disjoint slots while s-Turn != tkt : Pause assert s-MailBox == null s-MailBox = v // deposit and pass message Take() : // consumer : partial method - waits as necessary auto tkt = AtomicFetchIncrement (&TakeCursor,1) slot * s = &Slots[tkt & Mask] // 2-stage waiting : // First wait for turn for our generation // Acquire exclusive "take" access to slot's MailBox field // Then wait for the slot to become occupied while s-Turn != tkt : Pause // Concurrency in this section of code is now reduced to just 1 producer thread // vs 1 consumer thread. // For a given queue and slot, there will be most one Take() operation running // in this section. // Consumer waits for producer to arrive and make slot non-empty // Extract message; clear mailbox; advance Turn indicator // We have an obvious happens-before relation : // Put(m) happens-before corresponding Take() that returns that same "m" for T v = s-MailBox if v != null : s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 // unlock slot to admit next producer and consumer return v Pause tryTake() : // total method - returns ASAP with failure indication for auto tkt = TakeCursor slot * s = &Slots[tkt & Mask] if s-Turn != tkt : return null T v = s-MailBox // presumptive return value if v == null : return null // ratify tkt and v values and commit by advancing cursor if CAS (&TakeCursor, tkt, tkt+1) != tkt : continue s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 return v The basic idea derives from the Partitioned Ticket Lock "PTL" (US20120240126-A1) and the MultiLane Concurrent Bag (US8689237). The latter is essentially a circular ring-buffer where the elements themselves are queues or concurrent collections. You can think of the PTLQueue as a partitioned ticket lock "PTL" augmented to pass values from lock to unlock via the slots. Alternatively, you could conceptualize of PTLQueue as a degenerate MultiLane bag where each slot or "lane" consists of a simple single-word MailBox instead of a general queue. Each lane in PTLQueue also has a private Turn field which acts like the Turn (Grant) variables found in PTL. Turn enforces strict FIFO ordering and restricts concurrency on the slot mailbox field to at most one simultaneous put() and take() operation. PTL uses a single "ticket" variable and per-slot Turn (grant) fields while MultiLane has distinct PutCursor and TakeCursor cursors and abstract per-slot sub-queues. Both PTL and MultiLane advance their cursor and ticket variables with atomic fetch-and-increment. PTLQueue borrows from both PTL and MultiLane and has distinct put and take cursors and per-slot Turn fields. Instead of a per-slot queues, PTLQueue uses a simple single-word MailBox field. PutCursor and TakeCursor act like a pair of ticket locks, conferring "put" and "take" access to a given slot. PutCursor, for instance, assigns an incoming put() request to a slot and serves as a PTL "Ticket" to acquire "put" permission to that slot's MailBox field. To better explain the operation of PTLQueue we deconstruct the operation of put() and take() as follows. Put() first increments PutCursor obtaining a new unique ticket. That ticket value also identifies a slot. Put() next waits for that slot's Turn field to match that ticket value. This is tantamount to using a PTL to acquire "put" permission on the slot's MailBox field. Finally, having obtained exclusive "put" permission on the slot, put() stores the message value into the slot's MailBox. Take() similarly advances TakeCursor, identifying a slot, and then acquires and secures "take" permission on a slot by waiting for Turn. Take() then waits for the slot's MailBox to become non-empty, extracts the message, and clears MailBox. Finally, take() advances the slot's Turn field, which releases both "put" and "take" access to the slot's MailBox. Note the asymmetry : put() acquires "put" access to the slot, but take() releases that lock. At any given time, for a given slot in a PTLQueue, at most one thread has "put" access and at most one thread has "take" access. This restricts concurrency from general MPMC to 1-vs-1. We have 2 ticket locks -- one for put() and one for take() -- each with its own "ticket" variable in the form of the corresponding cursor, but they share a single "Grant" egress variable in the form of the slot's Turn variable. Advancing the PutCursor, for instance, serves two purposes. First, we obtain a unique ticket which identifies a slot. Second, incrementing the cursor is the doorway protocol step to acquire the per-slot mutual exclusion "put" lock. The cursors and operations to increment those cursors serve double-duty : slot-selection and ticket assignment for locking the slot's MailBox field. At any given time a slot MailBox field can be in one of the following states: empty with no pending operations -- neutral state; empty with one or more waiting take() operations pending -- deficit; occupied with no pending operations; occupied with one or more waiting put() operations -- surplus; empty with a pending put() or pending put() and take() operations -- transitional; or occupied with a pending take() or pending put() and take() operations -- transitional. The partial put() and take() operators can be implemented with an atomic fetch-and-increment operation, which may confer a performance advantage over a CAS-based loop. In addition we have independent PutCursor and TakeCursor cursors. Critically, a put() operation modifies PutCursor but does not access the TakeCursor and a take() operation modifies the TakeCursor cursor but does not access the PutCursor. This acts to reduce coherence traffic relative to some other queue designs. It's worth noting that slow threads or obstruction in one slot (or "lane") does not impede or obstruct operations in other slots -- this gives us some degree of obstruction isolation. PTLQueue is not lock-free, however. The implementation above is expressed with polite busy-waiting (Pause) but it's trivial to implement per-slot parking and unparking to deschedule waiting threads. It's also easy to convert the queue to a more general deque by replacing the PutCursor and TakeCursor cursors with Left/Front and Right/Back cursors that can move either direction. Specifically, to push and pop from the "left" side of the deque we would decrement and increment the Left cursor, respectively, and to push and pop from the "right" side of the deque we would increment and decrement the Right cursor, respectively. We used a variation of PTLQueue for message passing in our recent OPODIS 2013 paper. ul { list-style:none; padding-left:0; padding:0; margin:0; margin-left:0; } ul#myTagID { padding: 0px; margin: 0px; list-style:none; margin-left:0;} -- -- There's quite a bit of related literature in this area. I'll call out a few relevant references: Wilson's NYU Courant Institute UltraComputer dissertation from 1988 is classic and the canonical starting point : Operating System Data Structures for Shared-Memory MIMD Machines with Fetch-and-Add. Regarding provenance and priority, I think PTLQueue or queues effectively equivalent to PTLQueue have been independently rediscovered a number of times. See CB-Queue and BNPBV, below, for instance. But Wilson's dissertation anticipates the basic idea and seems to predate all the others. Gottlieb et al : Basic Techniques for the Efficient Coordination of Very Large Numbers of Cooperating Sequential Processors Orozco et al : CB-Queue in Toward high-throughput algorithms on many-core architectures which appeared in TACO 2012. Meneghin et al : BNPVB family in Performance evaluation of inter-thread communication mechanisms on multicore/multithreaded architecture Dmitry Vyukov : bounded MPMC queue (highly recommended) Alex Otenko : US8607249 (highly related). John Mellor-Crummey : Concurrent queues: Practical fetch-and-phi algorithms. Technical Report 229, Department of Computer Science, University of Rochester Thomasson : FIFO Distributed Bakery Algorithm (very similar to PTLQueue). Scott and Scherer : Dual Data Structures I'll propose an optimization left as an exercise for the reader. Say we wanted to reduce memory usage by eliminating inter-slot padding. Such padding is usually "dark" memory and otherwise unused and wasted. But eliminating the padding leaves us at risk of increased false sharing. Furthermore lets say it was usually the case that the PutCursor and TakeCursor were numerically close to each other. (That's true in some use cases). We might still reduce false sharing by incrementing the cursors by some value other than 1 that is not trivially small and is coprime with the number of slots. Alternatively, we might increment the cursor by one and mask as usual, resulting in a logical index. We then use that logical index value to index into a permutation table, yielding an effective index for use in the slot array. The permutation table would be constructed so that nearby logical indices would map to more distant effective indices. (Open question: what should that permutation look like? Possibly some perversion of a Gray code or De Bruijn sequence might be suitable). As an aside, say we need to busy-wait for some condition as follows : "while C == 0 : Pause". Lets say that C is usually non-zero, so we typically don't wait. But when C happens to be 0 we'll have to spin for some period, possibly brief. We can arrange for the code to be more machine-friendly with respect to the branch predictors by transforming the loop into : "if C == 0 : for { Pause; if C != 0 : break; }". Critically, we want to restructure the loop so there's one branch that controls entry and another that controls loop exit. A concern is that your compiler or JIT might be clever enough to transform this back to "while C == 0 : Pause". You can sometimes avoid this by inserting a call to a some type of very cheap "opaque" method that the compiler can't elide or reorder. On Solaris, for instance, you could use :"if C == 0 : { gethrtime(); for { Pause; if C != 0 : break; }}". It's worth noting the obvious duality between locks and queues. If you have strict FIFO lock implementation with local spinning and succession by direct handoff such as MCS or CLH,then you can usually transform that lock into a queue. Hidden commentary and annotations - invisible : * And of course there's a well-known duality between queues and locks, but I'll leave that topic for another blog post. * Compare and contrast : PTLQ vs PTL and MultiLane * Equivalent : Turn; seq; sequence; pos; position; ticket * Put = Lock; Deposit Take = identify and reserve slot; wait; extract & clear; unlock * conceptualize : Distinct PutLock and TakeLock implemented as ticket lock or PTL Distinct arrival cursors but share per-slot "Turn" variable provides exclusive role-based access to slot's mailbox field put() acquires exclusive access to a slot for purposes of "deposit" assigns slot round-robin and then acquires deposit access rights/perms to that slot take() acquires exclusive access to slot for purposes of "withdrawal" assigns slot round-robin and then acquires withdrawal access rights/perms to that slot At any given time, only one thread can have withdrawal access to a slot at any given time, only one thread can have deposit access to a slot Permissible for T1 to have deposit access and T2 to simultaneously have withdrawal access * round-robin for the purposes of; role-based; access mode; access role mailslot; mailbox; allocate/assign/identify slot rights; permission; license; access permission; * PTL/Ticket hybrid Asymmetric usage ; owner oblivious lock-unlock pairing K-exclusion add Grant cursor pass message m from lock to unlock via Slots[] array Cursor performs 2 functions : + PTL ticket + Assigns request to slot in round-robin fashion Deconstruct protocol : explication put() : allocate slot in round-robin fashion acquire PTL for "put" access store message into slot associated with PTL index take() : Acquire PTL for "take" access // doorway step seq = fetchAdd (&Grant, 1) s = &Slots[seq & Mask] // waiting phase while s-Turn != seq : pause Extract : wait for s-mailbox to be full v = s-mailbox s-mailbox = null Release PTL for both "put" and "take" access s-Turn = seq + Mask + 1 * Slot round-robin assignment and lock "doorway" protocol leverage the same cursor and FetchAdd operation on that cursor FetchAdd (&Cursor,1) + round-robin slot assignment and dispersal + PTL/ticket lock "doorway" step waiting phase is via "Turn" field in slot * PTLQueue uses 2 cursors -- put and take. Acquire "put" access to slot via PTL-like lock Acquire "take" access to slot via PTL-like lock 2 locks : put and take -- at most one thread can access slot's mailbox Both locks use same "turn" field Like multilane : 2 cursors : put and take slot is simple 1-capacity mailbox instead of queue Borrow per-slot turn/grant from PTL Provides strict FIFO Lock slot : put-vs-put take-vs-take at most one put accesses slot at any one time at most one put accesses take at any one time reduction to 1-vs-1 instead of N-vs-M concurrency Per slot locks for put/take Release put/take by advancing turn * is instrumental in ... * P-V Semaphore vs lock vs K-exclusion * See also : FastQueues-excerpt.java dice-etc/queue-mpmc-bounded-blocking-circular-xadd/ * PTLQueue is the same as PTLQB - identical * Expedient return; ASAP; prompt; immediately * Lamport's Bakery algorithm : doorway step then waiting phase Threads arriving at doorway obtain a unique ticket number Threads enter in ticket order * In the terminology of Reed and Kanodia a ticket lock corresponds to the busy-wait implementation of a semaphore using an eventcount and a sequencer It can also be thought of as an optimization of Lamport's bakery lock was designed for fault-tolerance rather than performance Instead of spinning on the release counter, processors using a bakery lock repeatedly examine the tickets of their peers --

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JBOSS 7.1 started hanging after 6 months of deployment

- by PVR

My application is been live from 6 months. The application is host on jboss 7.1 server. From last few days I am finding numerous problem of hanging of jboss server. Though I restart the jboss server again, it does not invoke. I need to restart the server machine itself. Can anyone please let me know what could be the cause of these problems and the workable resolutions or any suggestion ? Kindly dont degrade the question as I am facing a lot problems due to this hanging issue. Also for the information, the application is based on Java, GWT, Hibernate 3. Please find the standalone.xml file in case if it helps. <extensions> <extension module="org.jboss.as.clustering.infinispan"/> <extension module="org.jboss.as.configadmin"/> <extension module="org.jboss.as.connector"/> <extension module="org.jboss.as.deployment-scanner"/> <extension module="org.jboss.as.ee"/> <extension module="org.jboss.as.ejb3"/> <extension module="org.jboss.as.jaxrs"/> <extension module="org.jboss.as.jdr"/> <extension module="org.jboss.as.jmx"/> <extension module="org.jboss.as.jpa"/> <extension module="org.jboss.as.logging"/> <extension module="org.jboss.as.mail"/> <extension module="org.jboss.as.naming"/> <extension module="org.jboss.as.osgi"/> <extension module="org.jboss.as.pojo"/> <extension module="org.jboss.as.remoting"/> <extension module="org.jboss.as.sar"/> <extension module="org.jboss.as.security"/> <extension module="org.jboss.as.threads"/> <extension module="org.jboss.as.transactions"/> <extension module="org.jboss.as.web"/> <extension module="org.jboss.as.webservices"/> <extension module="org.jboss.as.weld"/> </extensions> <system-properties> <property name="org.apache.coyote.http11.Http11Protocol.COMPRESSION" value="on"/> <property name="org.apache.coyote.http11.Http11Protocol.COMPRESSION_MIME_TYPES" value="text/javascript,text/css,text/html,text/xml,text/json"/> </system-properties> <management> <security-realms> <security-realm name="ManagementRealm"> <authentication> <properties path="mgmt-users.properties" relative-to="jboss.server.config.dir"/> </authentication> </security-realm> <security-realm name="ApplicationRealm"> <authentication> <properties path="application-users.properties" relative-to="jboss.server.config.dir"/> </authentication> </security-realm> </security-realms> <management-interfaces> <native-interface security-realm="ManagementRealm"> <socket-binding native="management-native"/> </native-interface> <http-interface security-realm="ManagementRealm"> <socket-binding http="management-http"/> </http-interface> </management-interfaces> </management> <profile> <subsystem xmlns="urn:jboss:domain:logging:1.1"> <console-handler name="CONSOLE"> <level name="INFO"/> <formatter> <pattern-formatter pattern="%d{HH:mm:ss,SSS} %-5p [%c] (%t) %s%E%n"/> </formatter> </console-handler> <periodic-rotating-file-handler name="FILE"> <formatter> <pattern-formatter pattern="%d{HH:mm:ss,SSS} %-5p [%c] (%t) %s%E%n"/> </formatter> <file relative-to="jboss.server.log.dir" path="server.log"/> <suffix value=".yyyy-MM-dd"/> <append value="true"/> </periodic-rotating-file-handler> <logger category="com.arjuna"> <level name="WARN"/> </logger> <logger category="org.apache.tomcat.util.modeler"> <level name="WARN"/> </logger> <logger category="sun.rmi"> <level name="WARN"/> </logger> <logger category="jacorb"> <level name="WARN"/> </logger> <logger category="jacorb.config"> <level name="ERROR"/> </logger> <root-logger> <level name="INFO"/> <handlers> <handler name="CONSOLE"/> <handler name="FILE"/> </handlers> </root-logger> </subsystem> <subsystem xmlns="urn:jboss:domain:configadmin:1.0"/> <subsystem xmlns="urn:jboss:domain:datasources:1.0"> <datasources> <datasource jndi-name="java:jboss/datasources/ExampleDS" pool-name="ExampleDS" enabled="true" use-java-context="true"> <connection-url>jdbc:h2:mem:test;DB_CLOSE_DELAY=-1</connection-url> <driver>h2</driver> <security> <user-name>sa</user-name> <password>sa</password> </security> </datasource> <drivers> <driver name="h2" module="com.h2database.h2"> <xa-datasource-class>org.h2.jdbcx.JdbcDataSource</xa-datasource-class> </driver> </drivers> </datasources> </subsystem> <subsystem xmlns="urn:jboss:domain:deployment-scanner:1.1"> <deployment-scanner path="deployments" relative-to="jboss.server.base.dir" scan-interval="5000"/> </subsystem> <subsystem xmlns="urn:jboss:domain:ee:1.0"/> <subsystem xmlns="urn:jboss:domain:ejb3:1.2"> <session-bean> <stateless> <bean-instance-pool-ref pool-name="slsb-strict-max-pool"/> </stateless> <stateful default-access-timeout="5000" cache-ref="simple"/> <singleton default-access-timeout="5000"/> </session-bean> <pools> <bean-instance-pools> <strict-max-pool name="slsb-strict-max-pool" max-pool-size="20" instance-acquisition-timeout="5" instance-acquisition-timeout-unit="MINUTES"/> <strict-max-pool name="mdb-strict-max-pool" max-pool-size="20" instance-acquisition-timeout="5" instance-acquisition-timeout-unit="MINUTES"/> </bean-instance-pools> </pools> <caches> <cache name="simple" aliases="NoPassivationCache"/> <cache name="passivating" passivation-store-ref="file" aliases="SimpleStatefulCache"/> </caches> <passivation-stores> <file-passivation-store name="file"/> </passivation-stores> <async thread-pool-name="default"/> <timer-service thread-pool-name="default"> <data-store path="timer-service-data" relative-to="jboss.server.data.dir"/> </timer-service> <remote connector-ref="remoting-connector" thread-pool-name="default"/> <thread-pools> <thread-pool name="default"> <max-threads count="10"/> <keepalive-time time="100" unit="milliseconds"/> </thread-pool> </thread-pools> </subsystem> <subsystem xmlns="urn:jboss:domain:infinispan:1.2" default-cache-container="hibernate"> <cache-container name="hibernate" default-cache="local-query"> <local-cache name="entity"> <transaction mode="NON_XA"/> <eviction strategy="LRU" max-entries="10000"/> <expiration max-idle="100000"/> </local-cache> <local-cache name="local-query"> <transaction mode="NONE"/> <eviction strategy="LRU" max-entries="10000"/> <expiration max-idle="100000"/> </local-cache> <local-cache name="timestamps"> <transaction mode="NONE"/> <eviction strategy="NONE"/> </local-cache> </cache-container> </subsystem> <subsystem xmlns="urn:jboss:domain:jaxrs:1.0"/> <subsystem xmlns="urn:jboss:domain:jca:1.1"> <archive-validation enabled="true" fail-on-error="true" fail-on-warn="false"/> <bean-validation enabled="true"/> <default-workmanager> <short-running-threads> <core-threads count="50"/> <queue-length count="50"/> <max-threads count="50"/> <keepalive-time time="10" unit="seconds"/> </short-running-threads> <long-running-threads> <core-threads count="50"/> <queue-length count="50"/> <max-threads count="50"/> <keepalive-time time="100" unit="seconds"/> </long-running-threads> </default-workmanager> <cached-connection-manager/> </subsystem> <subsystem xmlns="urn:jboss:domain:jdr:1.0"/> <subsystem xmlns="urn:jboss:domain:jmx:1.1"> <show-model value="true"/> <remoting-connector/> </subsystem> <subsystem xmlns="urn:jboss:domain:jpa:1.0"> <jpa default-datasource=""/> </subsystem> <subsystem xmlns="urn:jboss:domain:mail:1.0"> <mail-session jndi-name="java:jboss/mail/Default"> <smtp-server outbound-socket-binding-ref="mail-smtp"/> </mail-session> </subsystem> <subsystem xmlns="urn:jboss:domain:naming:1.1"/> <subsystem xmlns="urn:jboss:domain:osgi:1.2" activation="lazy"> <properties> <property name="org.osgi.framework.startlevel.beginning"> 1 </property> </properties> <capabilities> <capability name="javax.servlet.api:v25"/> <capability name="javax.transaction.api"/> <capability name="org.apache.felix.log" startlevel="1"/> <capability name="org.jboss.osgi.logging" startlevel="1"/> <capability name="org.apache.felix.configadmin" startlevel="1"/> <capability name="org.jboss.as.osgi.configadmin" startlevel="1"/> </capabilities> </subsystem> <subsystem xmlns="urn:jboss:domain:pojo:1.0"/> <subsystem xmlns="urn:jboss:domain:remoting:1.1"> <connector name="remoting-connector" socket-binding="remoting" security-realm="ApplicationRealm"/> </subsystem> <subsystem xmlns="urn:jboss:domain:resource-adapters:1.0"/> <subsystem xmlns="urn:jboss:domain:sar:1.0"/> <subsystem xmlns="urn:jboss:domain:security:1.1"> <security-domains> <security-domain name="other" cache-type="default"> <authentication> <login-module code="Remoting" flag="optional"> <module-option name="password-stacking" value="useFirstPass"/> </login-module> <login-module code="RealmUsersRoles" flag="required"> <module-option name="usersProperties" value="${jboss.server.config.dir}/application-users.properties"/> <module-option name="rolesProperties" value="${jboss.server.config.dir}/application-roles.properties"/> <module-option name="realm" value="ApplicationRealm"/> <module-option name="password-stacking" value="useFirstPass"/> </login-module> </authentication> </security-domain> <security-domain name="jboss-web-policy" cache-type="default"> <authorization> <policy-module code="Delegating" flag="required"/> </authorization> </security-domain> <security-domain name="jboss-ejb-policy" cache-type="default"> <authorization> <policy-module code="Delegating" flag="required"/> </authorization> </security-domain> </security-domains> </subsystem> <subsystem xmlns="urn:jboss:domain:threads:1.1"/> <subsystem xmlns="urn:jboss:domain:transactions:1.1"> <core-environment> <process-id> <uuid/> </process-id> </core-environment> <recovery-environment socket-binding="txn-recovery-environment" status-socket-binding="txn-status-manager"/> <coordinator-environment default-timeout="300"/> </subsystem> <subsystem xmlns="urn:jboss:domain:web:1.1" default-virtual-server="default-host" native="false"> <connector name="http" protocol="HTTP/1.1" scheme="http" socket-binding="http"/> <virtual-server name="default-host" enable-welcome-root="false"> <alias name="localhost"/> <alias name="nextenders.com"/> </virtual-server> </subsystem> <subsystem xmlns="urn:jboss:domain:webservices:1.1"> <modify-wsdl-address>true</modify-wsdl-address> <wsdl-host>${jboss.bind.address:127.0.0.1}</wsdl-host> <endpoint-config name="Standard-Endpoint-Config"/> <endpoint-config name="Recording-Endpoint-Config"> <pre-handler-chain name="recording-handlers" protocol-bindings="##SOAP11_HTTP ##SOAP11_HTTP_MTOM ##SOAP12_HTTP ##SOAP12_HTTP_MTOM"> <handler name="RecordingHandler" class="org.jboss.ws.common.invocation.RecordingServerHandler"/> </pre-handler-chain> </endpoint-config> </subsystem> <subsystem xmlns="urn:jboss:domain:weld:1.0"/> </profile> <interfaces> <interface name="management"> <inet-address value="${jboss.bind.address.management:127.0.0.1}"/> </interface> <interface name="public"> <inet-address value="${jboss.bind.address:127.0.0.1}"/> </interface> <interface name="unsecure"> <inet-address value="${jboss.bind.address.unsecure:127.0.0.1}"/> </interface> </interfaces> <socket-binding-group name="standard-sockets" default-interface="public" port-offset="${jboss.socket.binding.port-offset:0}"> <socket-binding name="management-native" interface="management" port="${jboss.management.native.port:9999}"/> <socket-binding name="management-http" interface="management" port="${jboss.management.http.port:9990}"/> <socket-binding name="management-https" interface="management" port="${jboss.management.https.port:9443}"/> <socket-binding name="ajp" port="8009"/> <socket-binding name="http" port="80"/> <socket-binding name="https" port="443"/> <socket-binding name="osgi-http" interface="management" port="8090"/> <socket-binding name="remoting" port="4447"/> <socket-binding name="txn-recovery-environment" port="4712"/> <socket-binding name="txn-status-manager" port="4713"/> <outbound-socket-binding name="mail-smtp"> <remote-destination host="localhost" port="25"/> </outbound-socket-binding> </socket-binding-group>

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How to get full query string parameters not UrlDecoded

- by developerit

Introduction While developing Developer IT’s website, we came across a problem when the user search keywords containing special character like the plus ‘+’ char. We found it while looking for C++ in our search engine. The request parameter output in ASP.NET was “c “. I found it strange that it removed the ‘++’ and replaced it with a space… Analysis After a bit of Googling and Reflection, it turns out that ASP.NET calls UrlDecode on each parameters retreived by the Request(“item”) method. The Request.Params property is affected by this two since it mashes all QueryString, Forms and other collections into a single one. Workaround Finally, I solve the puzzle usign the Request.RawUrl property and parsing it with the same RegEx I use in my url re-writter. The RawUrl not affected by anything. As its name say it, it’s raw. Published on http://www.developerit.com/

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Dell PowerEdge R720xd stuck in BIOS

- by G_P

I have a Dell PowerEdge R720xd that gets stuck in the BIOS when booting. It successfully gets past the "configuring memory" and "configuring iDRAC" screens, but once it shows the "CPLD version : 103" with the various management engine versions/patches, it just hangs. No errors messages are displayed. This started happening when we tried adding additional RAM to the machine. Since then, we tried re-seating the new memory which resulted in the same issue. Then, we took out all the new memory, and the problem persists. We have also tried pressing F2 to get into System Setup, but it just indicates "Entering System Setup" and hangs at the same point. Has anybody seen this issue before or have any ideas on what to try next? UPDATE After troubleshooting and trying to isolate the issue (stripping things down to a single CPU and single DIMM, same problem, swapping to the other CPU and a different DIMM, same problem), Dell support will be coming out to swap the system board.

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Using LINQ Distinct: With an Example on ASP.NET MVC SelectListItem

- by Joe Mayo

One of the things that might be surprising in the LINQ Distinct standard query operator is that it doesn’t automatically work properly on custom classes. There are reasons for this, which I’ll explain shortly. The example I’ll use in this post focuses on pulling a unique list of names to load into a drop-down list. I’ll explain the sample application, show you typical first shot at Distinct, explain why it won’t work as you expect, and then demonstrate a solution to make Distinct work with any custom class. The technologies I’m using are LINQ to Twitter, LINQ to Objects, Telerik Extensions for ASP.NET MVC, ASP.NET MVC 2, and Visual Studio 2010. The function of the example program is to show a list of people that I follow. In Twitter API vernacular, these people are called “Friends”; though I’ve never met most of them in real life. This is part of the ubiquitous language of social networking, and Twitter in particular, so you’ll see my objects named accordingly. Where Distinct comes into play is because I want to have a drop-down list with the names of the friends appearing in the list. Some friends are quite verbose, which means I can’t just extract names from each tweet and populate the drop-down; otherwise, I would end up with many duplicate names. Therefore, Distinct is the appropriate operator to eliminate the extra entries from my friends who tend to be enthusiastic tweeters. The sample doesn’t do anything with the drop-down list and I leave that up to imagination for what it’s practical purpose could be; perhaps a filter for the list if I only want to see a certain person’s tweets or maybe a quick list that I plan to combine with a TextBox and Button to reply to a friend. When the program runs, you’ll need to authenticate with Twitter, because I’m using OAuth (DotNetOpenAuth), for authentication, and then you’ll see the drop-down list of names above the grid with the most recent tweets from friends. Here’s what the application looks like when it runs: As you can see, there is a drop-down list above the grid. The drop-down list is where most of the focus of this article will be. There is some description of the code before we talk about the Distinct operator, but we’ll get there soon. This is an ASP.NET MVC2 application, written with VS 2010. Here’s the View that produces this screen: <%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<TwitterFriendsViewModel>" %> <%@ Import Namespace="DistinctSelectList.Models" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server"> Home Page </asp:Content><asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <fieldset> <legend>Twitter Friends</legend> <div> <%= Html.DropDownListFor( twendVM => twendVM.FriendNames, Model.FriendNames, "<All Friends>") %> </div> <div> <% Html.Telerik().Grid<TweetViewModel>(Model.Tweets) .Name("TwitterFriendsGrid") .Columns(cols => { cols.Template(col => { %> <img src="<%= col.ImageUrl %>" alt="<%= col.ScreenName %>" /> <% }); cols.Bound(col => col.ScreenName); cols.Bound(col => col.Tweet); }) .Render(); %> </div> </fieldset> </asp:Content> As shown above, the Grid is from Telerik’s Extensions for ASP.NET MVC. The first column is a template that renders the user’s Avatar from a URL provided by the Twitter query. Both the Grid and DropDownListFor display properties that are collections from a TwitterFriendsViewModel class, shown below: using System.Collections.Generic; using System.Web.Mvc; namespace DistinctSelectList.Models { /// /// For finding friend info on screen /// public class TwitterFriendsViewModel { /// /// Display names of friends in drop-down list /// public List FriendNames { get; set; } /// /// Display tweets in grid /// public List Tweets { get; set; } } } I created the TwitterFreindsViewModel. The two Lists are what the View consumes to populate the DropDownListFor and Grid. Notice that FriendNames is a List of SelectListItem, which is an MVC class. Another custom class I created is the TweetViewModel (the type of the Tweets List), shown below: namespace DistinctSelectList.Models { /// /// Info on friend tweets /// public class TweetViewModel { /// /// User's avatar /// public string ImageUrl { get; set; } /// /// User's Twitter name /// public string ScreenName { get; set; } /// /// Text containing user's tweet /// public string Tweet { get; set; } } } The initial Twitter query returns much more information than we need for our purposes and this a special class for displaying info in the View. Now you know about the View and how it’s constructed. Let’s look at the controller next. The controller for this demo performs authentication, data retrieval, data manipulation, and view selection. I’ll skip the description of the authentication because it’s a normal part of using OAuth with LINQ to Twitter. Instead, we’ll drill down and focus on the Distinct operator. However, I’ll show you the entire controller, below, so that you can see how it all fits together: using System.Linq; using System.Web.Mvc; using DistinctSelectList.Models; using LinqToTwitter; namespace DistinctSelectList.Controllers { [HandleError] public class HomeController : Controller { private MvcOAuthAuthorization auth; private TwitterContext twitterCtx; /// /// Display a list of friends current tweets /// /// public ActionResult Index() { auth = new MvcOAuthAuthorization(InMemoryTokenManager.Instance, InMemoryTokenManager.AccessToken); string accessToken = auth.CompleteAuthorize(); if (accessToken != null) { InMemoryTokenManager.AccessToken = accessToken; } if (auth.CachedCredentialsAvailable) { auth.SignOn(); } else { return auth.BeginAuthorize(); } twitterCtx = new TwitterContext(auth); var friendTweets = (from tweet in twitterCtx.Status where tweet.Type == StatusType.Friends select new TweetViewModel { ImageUrl = tweet.User.ProfileImageUrl, ScreenName = tweet.User.Identifier.ScreenName, Tweet = tweet.Text }) .ToList(); var friendNames = (from tweet in friendTweets select new SelectListItem { Text = tweet.ScreenName, Value = tweet.ScreenName }) .Distinct() .ToList(); var twendsVM = new TwitterFriendsViewModel { Tweets = friendTweets, FriendNames = friendNames }; return View(twendsVM); } public ActionResult About() { return View(); } } } The important part of the listing above are the LINQ to Twitter queries for friendTweets and friendNames. Both of these results are used in the subsequent population of the twendsVM instance that is passed to the view. Let’s dissect these two statements for clarification and focus on what is happening with Distinct. The query for friendTweets gets a list of the 20 most recent tweets (as specified by the Twitter API for friend queries) and performs a projection into the custom TweetViewModel class, repeated below for your convenience: var friendTweets = (from tweet in twitterCtx.Status where tweet.Type == StatusType.Friends select new TweetViewModel { ImageUrl = tweet.User.ProfileImageUrl, ScreenName = tweet.User.Identifier.ScreenName, Tweet = tweet.Text }) .ToList(); The LINQ to Twitter query above simplifies what we need to work with in the View and the reduces the amount of information we have to look at in subsequent queries. Given the friendTweets above, the next query performs another projection into an MVC SelectListItem, which is required for binding to the DropDownList. This brings us to the focus of this blog post, writing a correct query that uses the Distinct operator. The query below uses LINQ to Objects, querying the friendTweets collection to get friendNames: var friendNames = (from tweet in friendTweets select new SelectListItem { Text = tweet.ScreenName, Value = tweet.ScreenName }) .Distinct() .ToList(); The above implementation of Distinct seems normal, but it is deceptively incorrect. After running the query above, by executing the application, you’ll notice that the drop-down list contains many duplicates. This will send you back to the code scratching your head, but there’s a reason why this happens. To understand the problem, we must examine how Distinct works in LINQ to Objects. Distinct has two overloads: one without parameters, as shown above, and another that takes a parameter of type IEqualityComparer<T>. In the case above, no parameters, Distinct will call EqualityComparer<T>.Default behind the scenes to make comparisons as it iterates through the list. You don’t have problems with the built-in types, such as string, int, DateTime, etc, because they all implement IEquatable<T>. However, many .NET Framework classes, such as SelectListItem, don’t implement IEquatable<T>. So, what happens is that EqualityComparer<T>.Default results in a call to Object.Equals, which performs reference equality on reference type objects. You don’t have this problem with value types because the default implementation of Object.Equals is bitwise equality. However, most of your projections that use Distinct are on classes, just like the SelectListItem used in this demo application. So, the reason why Distinct didn’t produce the results we wanted was because we used a type that doesn’t define its own equality and Distinct used the default reference equality. This resulted in all objects being included in the results because they are all separate instances in memory with unique references. As you might have guessed, the solution to the problem is to use the second overload of Distinct that accepts an IEqualityComparer<T> instance. If you were projecting into your own custom type, you could make that type implement IEqualityComparer<T>, but SelectListItem belongs to the .NET Framework Class Library. Therefore, the solution is to create a custom type to implement IEqualityComparer<T>, as in the SelectListItemComparer class, shown below: using System.Collections.Generic; using System.Web.Mvc; namespace DistinctSelectList.Models { public class SelectListItemComparer : EqualityComparer { public override bool Equals(SelectListItem x, SelectListItem y) { return x.Value.Equals(y.Value); } public override int GetHashCode(SelectListItem obj) { return obj.Value.GetHashCode(); } } } The SelectListItemComparer class above doesn’t implement IEqualityComparer<SelectListItem>, but rather derives from EqualityComparer<SelectListItem>. Microsoft recommends this approach for consistency with the behavior of generic collection classes. However, if your custom type already derives from a base class, go ahead and implement IEqualityComparer<T>, which will still work. EqualityComparer is an abstract class, that implements IEqualityComparer<T> with Equals and GetHashCode abstract methods. For the purposes of this application, the SelectListItem.Value property is sufficient to determine if two items are equal. Since SelectListItem.Value is type string, the code delegates equality to the string class. The code also delegates the GetHashCode operation to the string class.You might have other criteria in your own object and would need to define what it means for your object to be equal. Now that we have an IEqualityComparer<SelectListItem>, let’s fix the problem. The code below modifies the query where we want distinct values: var friendNames = (from tweet in friendTweets select new SelectListItem { Text = tweet.ScreenName, Value = tweet.ScreenName }) .Distinct(new SelectListItemComparer()) .ToList(); Notice how the code above passes a new instance of SelectListItemComparer as the parameter to the Distinct operator. Now, when you run the application, the drop-down list will behave as you expect, showing only a unique set of names. In addition to Distinct, other LINQ Standard Query Operators have overloads that accept IEqualityComparer<T>’s, You can use the same techniques as shown here, with SelectListItemComparer, with those other operators as well. Now you know how to resolve problems with getting Distinct to work properly and also have a way to fix problems with other operators that require equality comparisons. @JoeMayo

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SDL2 sprite batching and texture atlases

- by jms

I have been programming a 2D game in C++, using the SDL2 graphics API for rendering. My game concept currently features effects that could result in even tens of thousands of sprites being drawn simultaneously to the screen. I'd like to know what can be done for increasing rendering efficiency if the need arises, preferably using the SDL2 API only. I have previously given a quick look at OpenGL-based 2D rendering, and noticed that SDL2 lacks a command like int SDL_RenderCopyMulti(SDL_Renderer* renderer, SDL_Texture* texture, const SDL_Rect* srcrects, SDL_Rect* dstrects, int count) Which would permit SDL to benefit from two common techniques used for efficient 2D graphics: Texture batching: Sorting sprites by the texture used, and then simultaneously rendering as many sprites that use the same texture as possible, changing only the source area on the texture and the destination area on the render target between sprites. This allows the encapsulation of the whole operation in a single GPU command, reducing the overhead drastically from multiple distinct calls. Texture atlases: Instead of creating one texture for each frame of each animation of each sprite, combining multiple animations and even multiple sprites into a single large texture. This lessens the impact of changing the current texture when switching between sprites, as the correct texture is often ready to be used from the previous draw call. Furthemore the GPU is optimized for handling large textures, in contrast to the many tiny textures typically used for sprites. My question: Would SDL2 still get somewhat faster from any rudimentary sprite sorting or from combining multiple images into one texture thanks to automatic video driver optimizations? If I will encounter performance issues related to 2D rendering in the future, will I be forced to switch to OpenGL for lower level control over the GPU? Edit: Are there any plans to include such functionality in the near future?

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Upgrading Team Foundation Server 2008 to 2010

- by Martin Hinshelwood

I am sure you will have seen my posts on upgrading our internal Team Foundation Server from TFS2008 to TFS2010 Beta 2, RC and RTM, but what about a fresh upgrade of TFS2008 to TFS2010 using the RTM version of TFS. One of our clients is taking the plunge with TFS2010, so I have the job of doing the upgrade. It is sometimes very useful to have a team member that starts work when most of the Sydney workers are heading home as I can do the upgrade without impacting them. The down side is that if you have any blockers then you can be pretty sure that everyone that can deal with your problem is asleep I am starting with an existing blank installation of TFS 2010, but Adam Cogan let slip that he was the one that did the install so I thought it prudent to make sure that it was OK. Verifying Team Foundation Server 2010 We need to check that TFS 2010 has been installed correctly. First, check the Admin console and have a root about for any errors. Figure: Even the SQL Setup looks good. I don’t know how Adam did it! Backing up the Team Foundation Server 2008 Databases As we are moving from one server to another (recommended method) we will be taking a backup of our TFS2008 databases and resorting them to the SQL Server for the new TFS2010 Server. Do not just detach and reattach. This will cause problems with the version of the database. If you are running a test migration you just need to create a backup of the TFS 2008 databases, but if you are doing the live migration then you should stop IIS on the TFS 2008 server before you backup the databases. This will stop any inadvertent check-ins or changes to TFS 2008. Figure: Stop IIS before you take a backup to prevent any TFS 2008 changes being written to the database. It is good to leave a little time between taking the TFS 2008 server offline and commencing the upgrade as there is always one developer who has not finished and starts screaming. This time it was John Liu that needed 10 more minutes to make his changes and check-in, so I always give it 30 minutes and see if anyone screams. John Liu [SSW] said: are you doing something to TFS :-O MrHinsh [SSW UK][VS ALM MVP] said: I have stopped TFS 2008 as per my emails John Liu [SSW] said: haven't finish check in @_@ can we have it for 10mins? :) MrHinsh [SSW UK][VS ALM MVP] said: TFS 2008 has been started John Liu [SSW] said: I love you! -IM conversation at TFS Upgrade +25 minutes After John confirmed that he had everything done I turned IIS off again and made a cup of tea. There were no more screams so the upgrade can continue. Figure: Backup all of the databases for TFS and include the Reporting Services, just in case. Figure: Check that all the backups have been taken Once you have your backups, you need to copy them to your new TFS2010 server and restore them. This is a good way to proceed as if we have any problems, or just plain run out of time, then you just turn the TFS 2008 server back on and all you have lost is one upgrade day, and not 10 developer days. As per the rules, you should record the number of files and the total number of areas and iterations before the upgrade so you have something to compare to: TFS2008 File count: Type Count 1 1845 2 15770 Areas & Iterations: 139 You can use this to verify that the upgrade was successful. it should however be noted that the numbers in TFS 2010 will be bigger. This is due to some of the sorting out that TFS does during the upgrade process. Restore Team Foundation Server 2008 Databases Restoring the databases is much more time consuming than just attaching them as you need to do them one at a time. But you may be taking a backup of an operational database and need to restore all your databases to a particular point in time instead of to the latest. I am doing latest unless I encounter any problems. Figure: Restore each of the databases to either a latest or specific point in time. Figure: Restore all of the required databases Now that all of your databases are restored you now need to upgrade them to Team Foundation Server 2010. Upgrade Team Foundation Server 2008 Databases This is probably the easiest part of the process. You need to call a fire and forget command that will go off to the database specified, find the TFS 2008 databases and upgrade them to 2010. During this process all of the 6 main TFS 2008 databases are merged into the TfsVersionControl database, upgraded and then the database is renamed to TFS_[CollectionName]. The rename is only the database and not the physical files, so it is worth going back and renaming the physical file as well. This keeps everything neat and tidy. If you plan to keep the old TFS 2008 server around, for example if you are doing a test migration first, then you will need to change the TFS GUID. This GUID is unique to each TFS instance and is preserved when you upgrade. This GUID is used by the clients and they can get a little confused if there are two servers with the same one. To kick of the upgrade you need to open a command prompt and change the path to “C:\Program Files\Microsoft Team Foundation Server 2010\Tools” and run the “import” command in “tfsconfig”. TfsConfig import /sqlinstance:<Previous TFS Data Tier> /collectionName:<Collection Name> /confirmed Imports a TFS 2005 or 2008 data tier as a new project collection. Important: This command should only be executed after adequate backups have been performed. After you import, you will need to configure portal and reporting settings via the administration console. EXAMPLES -------- TfsConfig import /sqlinstance:tfs2008sql /collectionName:imported /confirmed TfsConfig import /sqlinstance:tfs2008sql\Instance /collectionName:imported /confirmed OPTIONS: -------- sqlinstance The sql instance of the TFS 2005 or 2008 data tier. The TFS databases at that location will be modified directly and will no longer be usable as previous version databases. Ensure you have back-ups. collectionName The name of the new Team Project Collection. confirmed Confirm that you have backed-up databases before importing. This command will automatically look for the TfsIntegration database and verify that all the other required databases exist. In this case it took around 5 minutes to complete the upgrade as the total database size was under 700MB. This was unlike the upgrade of SSW’s production database with over 17GB of data which took a few hours. At the end of the process you should get no errors and no warnings. The Upgrade operation on the ApplicationTier feature has completed. There were 0 errors and 0 warnings. As this is a new server and not a pure upgrade there should not be a problem with the GUID. If you think at any point you will be doing this more than once, for example doing a test migration, or merging many TFS 2008 instances into a single one, then you should go back and rename the physical TfsVersionControl.mdf file to the same as the new collection. This will avoid confusion later down the line. To do this, detach the new collection from the server and rename the physical files. Then reattach and change the physical file locations to match the new name. You can follow http://www.mssqltips.com/tip.asp?tip=1122 for a more detailed explanation of how to do this. Figure: Stop the collection so TFS does not take a wobbly when we detach the database. When you try to start the new collection again you will get a conflict with project names and will require to remove the Test Upgrade collection. This is fine and it just needs detached. Figure: Detaching the test upgrade from the new Team Foundation Server 2010 so we can start the new Collection again. You will now be able to start the new upgraded collection and you are ready for testing. Do you remember the stats we took off the TFS 2008 server? TFS2008 File count: Type Count 1 1845 2 15770 Areas & Iterations: 139 Well, now we need to compare them to the TFS 2010 stats, remembering that there will probably be more files under source control. TFS2010 File count: Type Count 1 19288 Areas & Iterations: 139 Lovely, the number of iterations are the same, and the number of files is bigger. Just what we were looking for. Testing the upgraded Team Foundation Server 2010 Project Collection Can we connect to the new collection and project? Figure: We can connect to the new collection and project. Figure: make sure you can connect to The upgraded projects and that you can see all of the files. Figure: Team Web Access is there and working. Note that for Team Web Access you now use the same port and URL as for TFS 2010. So in this case as I am running on the local box you need to use http://localhost:8080/tfs which will redirect you to http://localhost:8080/tfs/web for the web access. If you need to connect with a Visual Studio 2008 client you will need to use the full path of the new collection, http://[servername]/tfs/[collectionname] and this will work with all of your collections. With Visual Studio 2005 you will only be able to connect to the Default collection and in both VS2008 and VS2005 you will need to install the forward compatibility updates. Visual Studio Team System 2005 Service Pack 1 Forward Compatibility Update for Team Foundation Server 2010 Visual Studio Team System 2008 Service Pack 1 Forward Compatibility Update for Team Foundation Server 2010 To make sure that you have everything up to date, make sure that you run SSW Diagnostics and get all green ticks. Upgrade Done! At this point you can send out a notice to everyone that the upgrade is complete and and give them the connection details. You need to remember that at this stage we have 2008 project upgraded to run under TFS 2010 but it is still running under that same process template that it was running before. You can only “enable” 2010 features in a process template you can’t upgrade. So what to do? Well, you need to create a new project and migrate things you want to keep across. Souse code is easy, you can move or Branch, but Work Items are more difficult as you can’t move them between projects. This instance is complicated more as the old project uses the Conchango/EMC Scrum for Team System template and I will need to write a script/application to get the work items across with their attachments in tact. That is my next task! Technorati Tags: TFS 2010,TFS 2008,VS ALM

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July 2013 Release of the Ajax Control Toolkit

- by Stephen.Walther

I’m super excited to announce the July 2013 release of the Ajax Control Toolkit. You can download the new version of the Ajax Control Toolkit from CodePlex (http://ajaxControlToolkit.CodePlex.com) or install the Ajax Control Toolkit from NuGet: With this release, we have completely rewritten the way the Ajax Control Toolkit combines, minifies, gzips, and caches JavaScript files. The goal of this release was to improve the performance of the Ajax Control Toolkit and make it easier to create custom Ajax Control Toolkit controls. Improving Ajax Control Toolkit Performance Previous releases of the Ajax Control Toolkit optimized performance for a single page but not multiple pages. When you visited each page in an app, the Ajax Control Toolkit would combine all of the JavaScript files required by the controls in the page into a new JavaScript file. So, even if every page in your app used the exact same controls, visitors would need to download a new combined Ajax Control Toolkit JavaScript file for each page visited. Downloading new scripts for each page that you visit does not lead to good performance. In general, you want to make as few requests for JavaScript files as possible and take maximum advantage of caching. For most apps, you would get much better performance if you could specify all of the Ajax Control Toolkit controls that you need for your entire app and create a single JavaScript file which could be used across your entire app. What a great idea! Introducing Control Bundles With this release of the Ajax Control Toolkit, we introduce the concept of Control Bundles. You define a Control Bundle to indicate the set of Ajax Control Toolkit controls that you want to use in your app. You define Control Bundles in a file located in the root of your application named AjaxControlToolkit.config. For example, the following AjaxControlToolkit.config file defines two Control Bundles: <ajaxControlToolkit> <controlBundles> <controlBundle> <control name="CalendarExtender" /> <control name="ComboBox" /> </controlBundle> <controlBundle name="CalendarBundle"> <control name="CalendarExtender"></control> </controlBundle> </controlBundles> </ajaxControlToolkit> The first Control Bundle in the file above does not have a name. When a Control Bundle does not have a name then it becomes the default Control Bundle for your entire application. The default Control Bundle is used by the ToolkitScriptManager by default. For example, the default Control Bundle is used when you declare the ToolkitScriptManager like this: <ajaxToolkit:ToolkitScriptManager runat=”server” /> The default Control Bundle defined in the file above includes all of the scripts required for the CalendarExtender and ComboBox controls. All of the scripts required for both of these controls are combined, minified, gzipped, and cached automatically. The AjaxControlToolkit.config file above also defines a second Control Bundle with the name CalendarBundle. Here’s how you would use the CalendarBundle with the ToolkitScriptManager: <ajaxToolkit:ToolkitScriptManager runat="server"> <ControlBundles> <ajaxToolkit:ControlBundle Name="CalendarBundle" /> </ControlBundles> </ajaxToolkit:ToolkitScriptManager> In this case, only the JavaScript files required by the CalendarExtender control, and not the ComboBox, would be downloaded because the CalendarBundle lists only the CalendarExtender control. You can use multiple named control bundles with the ToolkitScriptManager and you will get all of the scripts from both bundles. Support for ControlBundles is a new feature of the ToolkitScriptManager that we introduced with this release. We extended the ToolkitScriptManager to support the Control Bundles that you can define in the AjaxControlToolkit.config file. Let me be explicit about the rules for Control Bundles: 1. If you do not create an AjaxControlToolkit.config file then the ToolkitScriptManager will download all of the JavaScript files required for all of the controls in the Ajax Control Toolkit. This is the easy but low performance option. 2. If you create an AjaxControlToolkit.config file and create a ControlBundle without a name then the ToolkitScriptManager uses that Control Bundle by default. For example, if you plan to use only the CalendarExtender and ComboBox controls in your application then you should create a default bundle that lists only these two controls. 3. If you create an AjaxControlToolkit.config file and create one or more named Control Bundles then you can use these named Control Bundles with the ToolkitScriptManager. For example, you might want to use different subsets of the Ajax Control Toolkit controls in different sections of your app. I should also mention that you can use the AjaxControlToolkit.config file with custom Ajax Control Toolkit controls – new controls that you write. For example, here is how you would register a set of custom controls from an assembly named MyAssembly: <ajaxControlToolkit> <controlBundles> <controlBundle name="CustomBundle"> <control name="MyAssembly.MyControl1" assembly="MyAssembly" /> <control name="MyAssembly.MyControl2" assembly="MyAssembly" /> </controlBundle> </ajaxControlToolkit> What about ASP.NET Bundling and Minification? The idea of Control Bundles is similar to the idea of Script Bundles used in ASP.NET Bundling and Minification. You might be wondering why we didn’t simply use Script Bundles with the Ajax Control Toolkit. There were several reasons. First, ASP.NET Bundling does not work with scripts embedded in an assembly. Because all of the scripts used by the Ajax Control Toolkit are embedded in the AjaxControlToolkit.dll assembly, ASP.NET Bundling was not an option. Second, Web Forms developers typically think at the level of controls and not at the level of individual scripts. We believe that it makes more sense for a Web Forms developer to specify the controls that they need in an app (CalendarExtender, ToggleButton) instead of the individual scripts that they need in an app (the 15 or so scripts required by the CalenderExtender). Finally, ASP.NET Bundling does not work with older versions of ASP.NET. The Ajax Control Toolkit needs to support ASP.NET 3.5, ASP.NET 4.0, and ASP.NET 4.5. Therefore, using ASP.NET Bundling was not an option. There is nothing wrong with using Control Bundles and Script Bundles side-by-side. The ASP.NET 4.0 and 4.5 ToolkitScriptManager supports both approaches to bundling scripts. Using the AjaxControlToolkit.CombineScriptsHandler Browsers cache JavaScript files by URL. For example, if you request the exact same JavaScript file from two different URLs then the exact same JavaScript file must be downloaded twice. However, if you request the same JavaScript file from the same URL more than once then it only needs to be downloaded once. With this release of the Ajax Control Toolkit, we have introduced a new HTTP Handler named the AjaxControlToolkit.CombineScriptsHandler. If you register this handler in your web.config file then the Ajax Control Toolkit can cache your JavaScript files for up to one year in the future automatically. You should register the handler in two places in your web.config file: in the <httpHandlers> section and the <system.webServer> section (don’t forget to register the handler for the AjaxFileUpload while you are there!). <httpHandlers> <add verb="*" path="AjaxFileUploadHandler.axd" type="AjaxControlToolkit.AjaxFileUploadHandler, AjaxControlToolkit" /> <add verb="*" path="CombineScriptsHandler.axd" type="AjaxControlToolkit.CombineScriptsHandler, AjaxControlToolkit" /> </httpHandlers> <system.webServer> <validation validateIntegratedModeConfiguration="false" /> <handlers> <add name="AjaxFileUploadHandler" verb="*" path="AjaxFileUploadHandler.axd" type="AjaxControlToolkit.AjaxFileUploadHandler, AjaxControlToolkit" /> <add name="CombineScriptsHandler" verb="*" path="CombineScriptsHandler.axd" type="AjaxControlToolkit.CombineScriptsHandler, AjaxControlToolkit" /> </handlers> <system.webServer> The handler is only used in release mode and not in debug mode. You can enable release mode in your web.config file like this: <compilation debug=”false”> You also can override the web.config setting with the ToolkitScriptManager like this: <act:ToolkitScriptManager ScriptMode=”Release” runat=”server”/> In release mode, scripts are combined, minified, gzipped, and cached with a far future cache header automatically. When the handler is not registered, scripts are requested from the page that contains the ToolkitScriptManager: When the handler is registered in the web.config file, scripts are requested from the handler: If you want the best performance, always register the handler. That way, the Ajax Control Toolkit can cache the bundled scripts across page requests with a far future cache header. If you don’t register the handler then a new JavaScript file must be downloaded whenever you travel to a new page. Dynamic Bundling and Minification Previous releases of the Ajax Control Toolkit used a Visual Studio build task to minify the JavaScript files used by the Ajax Control Toolkit controls. The disadvantage of this approach to minification is that it made it difficult to create custom Ajax Control Toolkit controls. Starting with this release of the Ajax Control Toolkit, we support dynamic minification. The JavaScript files in the Ajax Control Toolkit are minified at runtime instead of at build time. Scripts are minified only when in release mode. You can specify release mode with the web.config file or with the ToolkitScriptManager ScriptMode property. Because of this change, the Ajax Control Toolkit now depends on the Ajax Minifier. You must include a reference to AjaxMin.dll in your Visual Studio project or you cannot take advantage of runtime minification. If you install the Ajax Control Toolkit from NuGet then AjaxMin.dll is added to your project as a NuGet dependency automatically. If you download the Ajax Control Toolkit from CodePlex then the AjaxMin.dll is included in the download. This change means that you no longer need to do anything special to create a custom Ajax Control Toolkit. As an open source project, we hope more people will contribute to the Ajax Control Toolkit (Yes, I am looking at you.) We have been working hard on making it much easier to create new custom controls. More on this subject with the next release of the Ajax Control Toolkit. A Single Visual Studio Solution We also made substantial changes to the Visual Studio solution and projects used by the Ajax Control Toolkit with this release. This change will matter to you only if you need to work directly with the Ajax Control Toolkit source code. In previous releases of the Ajax Control Toolkit, we maintained separate solution and project files for ASP.NET 3.5, ASP.NET 4.0, and ASP.NET 4.5. Starting with this release, we now support a single Visual Studio 2012 solution that takes advantage of multi-targeting to build ASP.NET 3.5, ASP.NET 4.0, and ASP.NET 4.5 versions of the toolkit. This change means that you need Visual Studio 2012 to open the Ajax Control Toolkit project downloaded from CodePlex. For details on how we setup multi-targeting, please see Budi Adiono’s blog post: http://www.budiadiono.com/2013/07/25/visual-studio-2012-multi-targeting-framework-project/ Summary You can take advantage of this release of the Ajax Control Toolkit to significantly improve the performance of your website. You need to do two things: 1) You need to create an AjaxControlToolkit.config file which lists the controls used in your app and 2) You need to register the AjaxControlToolkit.CombineScriptsHandler in the web.config file. We made substantial changes to the Ajax Control Toolkit with this release. We think these changes will result in much better performance for multipage apps and make the process of building custom controls much easier. As always, we look forward to hearing your feedback.

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AWS RDS (SQL Server): SSL Connection - The target principal name is incorrect

- by AX1

I have a Amazon Web Services (AWS) Relational Database Service (RDS) instance running SQL Server 2012 Express. I've installed Amazon's aws.amazon.com/rds certificate in the client machine's Trusted Root Certification Authorities store. However, when I connect to the RDS instance (using SQL Server Management Studio 2012) and check off "Encrypt Connection", I get the following error: A connection was successfully established with the server, but then an error occurred during the login process. (provider: SSL Provider, error: 0 - The target principal name is incorrect.) (Microsoft SQL Server) What does this mean, and how can I fix it? Thanks!

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SQL Server Agent was not running on Server Dynamics CRM 2013

- by No1_Melman

I'm trying to install Dynamics CRM 2013 on a server. This server is on a VM. There are several other VMs, an ADDS & DNS, a MSSQL and a WebServer VM. Each server is a Windows Server 2012 R2. The SQL Server is 2012 Enterprise. Each VM is part of the main Domain, set by the ADDS & DNS. NSLookup confirms I can see the computer at the right IP address. Each separate VM has its own static IP, the DNS is set to the ADDS & DNS. I use the domain administrator to log into all the servers, and make the that domain administrator a local administrator. I've set up all the domain users for the CRM and gave them appropriate permissions, I have also added the accounts to the appropriate places, such that the CRM Deployment user is in the SQL security. The SQL Agent is running. SQL server configuration manager has SQL server network configuration TCP/IP enabled to allow remote connections. The SQL server has the domain user as a administrator, which is the same user being used to install the CRM. In the CRM setup i point to the [Servername]\[Instance] and I have also tried just the [Servername]. to make this easier I called the server MSSQL and left the instance name to the default. I even install the MSSQL instance as the domain administrator. CRM can find the ReportServer url. I have enable all the ports required, including: 135, 1433, 1434, 2382, 2383, 4022. 1434 UDP. I feel like I have absolutely done everything, I have google many times and tried all the different methods, and for the life of me I cant seem to get the CRM setup to find the SQL server agent. It passes everything else perfectly fine. I can even ping the MSSQL server. What is the problem, why does the CRM still keep giving the error: SQLSERVERAGENT (SQLSERVERAGENT) service is not running on the server MSSQL On the MSSQL server, the name of the sql server agent service is: SQL Server Agent (MSSQLSERVER)

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Oracle Linux Delivers Top CPU Benchmark Results on Sun Blades

- by sergio.leunissen

From the Performance and Best Practices blog: Fresh SPEC CPU2006 results for Sun Blade X6275 M2 Server Modules running Oracle Linux 5.5. The highlights: The dual-node Sun Blade X6275 M2 server module, equipped with two Intel Xeon X5670 2.93 GHz processors per node and running the Oracle Enterprise Linux 5.5 operating system delivered the best SPECint_rate2006 and SPECfp_rate2006 benchmark results for all systems with Intel Xeon processor 5000 sequence. With a SPECint_rate2006 benchmark result of 679, the Sun Blade X6275 M2 server module, with two compute nodes per blade, delivers maximum performance for space constrained environments. Comparing Oracle's dual-node blade to HP's dual-node blade server, based on their single node performance, the Sun Blade X6275 M2 server module SPECfp_rate2006 score of 241 outperforms the best published HP ProLiant BL2X220c G5 server score by 3.2x. A single node of a Sun Blade X6275 M2 server module using 2.93 GHz Intel Xeon X5670 processors delivered 37% improvement in SPECint_rate2006 benchmark results and 22% improvement in SPECfp_rate2006 benchmark results compared to the previous generation Sun Blade X6275 server module. Both nodes of a Sun Blade X6275 M2 server module using 2.93 GHz Intel Xeon X5670 processors delivered 59% improvement on the SPECint_rate2006 benchmark and 40% improvement on the SPECfp_rate2006 benchmark compared to the previous generation Sun Blade X6275 server module.

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How about a new platform for your next API… a CMS?

- by Elton Stoneman

Originally posted on: http://geekswithblogs.net/EltonStoneman/archive/2014/05/22/how-about-a-new-platform-for-your-next-apihellip-a.aspxSay what? I’m seeing a type of API emerge which serves static or long-lived resources, which are mostly read-only and have a controlled process to update the data that gets served. Think of something like an app configuration API, where you want a central location for changeable settings. You could use this server side to store database connection strings and keep all your instances in sync, or it could be used client side to push changes out to all users (and potentially driving A/B or MVT testing). That’s a good candidate for a RESTful API which makes proper use of HTTP expiration and validation caching to minimise traffic, but really you want a front end UI where you can edit the current config that the API returns and publish your changes. Sound like a Content Mangement System would be a good fit? I’ve been looking at that and it’s a great fit for this scenario. You get a lot of what you need out of the box, the amount of custom code you need to write is minimal, and you get a whole lot of extra stuff from using CMS which is very useful, but probably not something you’d build if you had to put together a quick UI over your API content (like a publish workflow, fine-grained security and an audit trail). You typically use a CMS for HTML resources, but it’s simple to expose JSON instead – or to do content negotiation to support both, so you can open a resource in a browser and see a nice visual representation, or request it with: Accept=application/json and get the same content rendered as JSON for the app to use. Enter Umbraco Umbraco is an open source .NET CMS that’s been around for a while. It has very good adoption, a lively community and a good release cycle. It’s easy to use, has all the functionality you need for a CMS-driven API, and it’s scalable (although you won’t necessarily put much scale on the CMS layer). In the rest of this post, I’ll build out a simple app config API using Umbraco. We’ll define the structure of the configuration resource by creating a new Document Type and setting custom properties; then we’ll build a very simple Razor template to return configuration documents as JSON; then create a resource and see how it looks. And we’ll look at how you could build this into a wider solution. If you want to try this for yourself, it’s ultra easy – there’s an Umbraco image in the Azure Website gallery, so all you need to to is create a new Website, select Umbraco from the image and complete the installation. It will create a SQL Azure website to store all the content, as well as a Website instance for editing and accessing content. They’re standard Azure resources, so you can scale them as you need. The default install creates a starter site for some HTML content, which you can use to learn your way around (or just delete). 1. Create Configuration Document Type In Umbraco you manage content by creating and modifying documents, and every document has a known type, defining what properties it holds. We’ll create a new Document Type to describe some basic config settings. In the Settings section from the left navigation (spanner icon), expand Document Types and Master, hit the ellipsis and select to create a new Document Type: This will base your new type off the Master type, which gives you some existing properties that we’ll use – like the Page Title which will be the resource URL. In the Generic Properties tab for the new Document Type, you set the properties you’ll be able to edit and return for the resource: Here I’ve added a text string where I’ll set a default cache lifespan, an image which I can use for a banner display, and a date which could show the user when the next release is due. This is the sort of thing that sits nicely in an app config API. It’s likely to change during the life of the product, but not very often, so it’s good to have a centralised place where you can make and publish changes easily and safely. It also enables A/B and MVT testing, as you can change the response each client gets based on your set logic, and their apps will behave differently without needing a release. 2. Define the response template Now we’ve defined the structure of the resource (as a document), in Umbraco we can define a C# Razor template to say how that resource gets rendered to the client. If you only want to provide JSON, it’s easy to render the content of the document by building each property in the response (Umbraco uses dynamic objects so you can specify document properties as object properties), or you can support content negotiation with very little effort. Here’s a template to render the document as HTML or JSON depending on the Accept header, using JSON.NET for the API rendering: @inherits Umbraco.Web.Mvc.UmbracoTemplatePage @using Newtonsoft.Json @{ Layout = null; } @if(UmbracoContext.HttpContext.Request.Headers["accept"] != null && UmbracoContext.HttpContext.Request.Headers["accept"] == "application/json") { Response.ContentType = "application/json"; @Html.Raw(JsonConvert.SerializeObject(new { cacheLifespan = CurrentPage.cacheLifespan, bannerImageUrl = CurrentPage.bannerImage, nextReleaseDate = CurrentPage.nextReleaseDate })) } else { <h1>App configuration</h1> <p>Cache lifespan: <b>@CurrentPage.cacheLifespan</b></p> <p>Banner Image: </p> <img src="@CurrentPage.bannerImage"> <p>Next Release Date: <b>@CurrentPage.nextReleaseDate</b></p> } That’s a rough-and ready example of what you can do. You could make it completely generic and just render all the document’s properties as JSON, but having a specific template for each resource gives you control over what gets sent out. And the templates are evaluated at run-time, so if you need to change the output – or extend it, say to add caching response headers – you just edit the template and save, and the next client request gets rendered from the new template. No code to build and ship. 3. Create the content With your document type created, in the Content pane you can create a new instance of that document, where Umbraco gives you a nice UI to input values for the properties we set up on the Document Type: Here I’ve set the cache lifespan to an xs:duration value, uploaded an image for the banner and specified a release date. Each property gets the appropriate input control – text box, file upload and date picker. At the top of the page is the name of the resource – myapp in this example. That specifies the URL for the resource, so if I had a DNS entry pointing to my Umbraco instance, I could access the config with a URL like http://static.x.y.z.com/config/myapp. The setup is all done now, so when we publish this resource it’ll be available to access. 4. Access the resource Now if you open that URL in the browser, you’ll see the HTML version rendered: - complete with the image and formatted date. Umbraco lets you save changes and preview them before publishing, so the HTML view could be a good way of showing editors their changes in a usable view, before they confirm them. If you browse the same URL from a REST client, specifying the Accept=application/json request header, you get this response: That’s the exact same resource, with a managed UI to publish it, being accessed as HTML or JSON with a tiny amount of effort. 5. The wider landscape If you have fairy stable content to expose as an API, I think this approach is really worth considering. Umbraco scales very nicely, but in a typical solution you probably wouldn’t need it to. When you have additional requirements, like logging API access requests - but doing it out-of-band so clients aren’t impacted, you can put a very thin API layer on top of Umbraco, and cache the CMS responses in your API layer: Here the API does a passthrough to CMS, so the CMS still controls the content, but it caches the response. If the response is cached for 1 minute, then Umbraco only needs to handle 1 request per minute (multiplied by the number of API instances), so if you need to support 1000s of request per second, you’re scaling a thin, simple API layer rather than having to scale the more complex CMS infrastructure (including the database). This diagram also shows an approach to logging, by asynchronously publishing a message to a queue (Redis in this case), which can be picked up later and persisted by a different process. Does it work? Beautifully. Using Azure, I spiked the solution above (including the Redis logging framework which I’ll blog about later) in half a day. That included setting up different roles in Umbraco to demonstrate a managed workflow for publishing changes, and a couple of document types representing different resources. Is it maintainable? We have three moving parts, which are all managed resources in Azure – an Azure Website for Umbraco which may need a couple of instances for HA (or may not, depending on how long the content can be cached), a message queue (Redis is in preview in Azure, but you can easily use Service Bus Queues if performance is less of a concern), and the Web Role for the API. Two of the components are off-the-shelf, from open source projects, and the only custom code is the API which is very simple. Does it scale? Pretty nicely. With a single Umbraco instance running as an Azure Website, and with 4x instances for my API layer (Standard sized Web Roles), I got just under 4,000 requests per second served reliably, with a Worker Role in the background saving the access logs. So we had a nice UI to publish app config changes, with a friendly Web preview and a publishing workflow, capable of supporting 14 million requests in an hour, with less than a day’s effort. Worth considering if you’re publishing long-lived resources through your API.

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Prolink 5200 modem/router connected to Linksys WRT54GS wireless router

- by lksanta

Hello does any one knows how to conect prolink 5200 single port modem/router with Linksys wireless router ......i dont know how to configerat these to togather

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Pure Server-Side Filtering with RadGridView and WCF RIA Services

Those of you who are familiar with WCF RIA Services know that the DomainDataSource control provides a FilterDescriptors collection that enables you to filter data returned by the query on the server. We have been using this DomainDataSource feature in our RIA Services with DomainDataSource online example for almost an year now. In the example, we are listening for RadGridViews Filtering event in order to intercept any filtering that is performed on the client and translate it to something that the DomainDataSource will understand, in this case a System.Windows.Data.FilterDescriptor being added or removed from its FilterDescriptors collection. Think of RadGridView.FilterDescriptors as client-side filtering and of DomainDataSource.FilterDescriptors as server-side filtering. We no longer need the client-side one. With the introduction of the Custom Filtering Controls feature many new possibilities have opened. With these custom controls we no longer need to do any filtering on the client. I have prepared a very small project that demonstrates how to filter solely on the server by using a custom filtering control. As I have already mentioned filtering on the server is done through the FilterDescriptors collection of the DomainDataSource control. This collection holds instances of type System.Windows.Data.FilterDescriptor. The FilterDescriptor has three important properties: PropertyPath: Specifies the name of the property that we want to filter on (the left operand). Operator: Specifies the type of comparison to use when filtering. An instance of FilterOperator Enumeration. Value: The value to compare with (the right operand). An instance of the Parameter Class. By adding filters, you can specify that only entities which meet the condition in the filter are loaded from the domain context. In case you are not familiar with these concepts you might find Brad Abrams blog interesting. Now, our requirements are to create some kind of UI that will manipulate the DomainDataSource.FilterDescriptors collection. When it comes to collections, my first choice of course would be RadGridView. If you are not familiar with the Custom Filtering Controls concept I would strongly recommend getting acquainted with my step-by-step tutorial Custom Filtering with RadGridView for Silverlight and checking the online example out. I have created a simple custom filtering control that contains a RadGridView and several buttons. This control is aware of the DomainDataSource instance, since it is operating on its FilterDescriptors collection. In fact, the RadGridView that is inside it is bound to this collection. In order to display filters that are relevant for the current column only, I have applied a filter to the grid. This filter is a Telerik.Windows.Data.FilterDescriptor and is used to filter the little grid inside the custom control. It should not be confused with the DomainDataSource.FilterDescriptors collection that RadGridView is actually bound to. These are the RIA filters. Additionally, I have added several other features. For example, if you have specified a DataFormatString on your original column, the Value column inside the custom control will pick it up and format the filter values accordingly. Also, I have transferred the data type of the column that you are filtering to the Value column of the custom control. This will help the little RadGridView determine what kind of editor to show up when you begin edit, for example a date picker for DateTime columns. Finally, I have added four buttons two of them can be used to add or remove filters and the other two will communicate the changes you have made to the server. Here is the full source code of the DomainDataSourceFilteringControl. The XAML: <UserControl x:Class="PureServerSideFiltering.DomainDataSourceFilteringControl" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:telerikGrid="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.GridView" xmlns:telerik="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls" Width="300"> <Border x:Name="LayoutRoot" BorderThickness="1" BorderBrush="#FF8A929E" Padding="5" Background="#FFDFE2E5"> <Grid> <Grid.RowDefinitions> <RowDefinition Height="Auto"/> <RowDefinition Height="150"/> <RowDefinition Height="Auto"/> </Grid.RowDefinitions> <StackPanel Grid.Row="0" Margin="2" Orientation="Horizontal" HorizontalAlignment="Center"> <telerik:RadButton Name="addFilterButton" Click="OnAddFilterButtonClick" Content="Add Filter" Margin="2" Width="96"/> <telerik:RadButton Name="removeFilterButton" Click="OnRemoveFilterButtonClick" Content="Remove Filter" Margin="2" Width="96"/> </StackPanel> <telerikGrid:RadGridView Name="filtersGrid" Grid.Row="1" Margin="2" ItemsSource="{Binding FilterDescriptors}" AddingNewDataItem="OnFilterGridAddingNewDataItem" ColumnWidth="*" ShowGroupPanel="False" AutoGenerateColumns="False" CanUserResizeColumns="False" CanUserReorderColumns="False" CanUserFreezeColumns="False" RowIndicatorVisibility="Collapsed" IsFilteringAllowed="False" CanUserSortColumns="False"> <telerikGrid:RadGridView.Columns> <telerikGrid:GridViewComboBoxColumn DataMemberBinding="{Binding Operator}" UniqueName="Operator"/> <telerikGrid:GridViewDataColumn Header="Value" DataMemberBinding="{Binding Value.Value}" UniqueName="Value"/> </telerikGrid:RadGridView.Columns> </telerikGrid:RadGridView> <StackPanel Grid.Row="2" Margin="2" Orientation="Horizontal" HorizontalAlignment="Center"> <telerik:RadButton Name="filterButton" Click="OnApplyFiltersButtonClick" Content="Apply Filters" Margin="2" Width="96"/> <telerik:RadButton Name="clearButton" Click="OnClearFiltersButtonClick" Content="Clear Filters" Margin="2" Width="96"/> </StackPanel> </Grid> </Border> </UserControl> And the code-behind: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes; using Telerik.Windows.Controls.GridView; using System.Windows.Data; using Telerik.Windows.Controls; using Telerik.Windows.Data; namespace PureServerSideFiltering { /// <summary> /// A custom filtering control capable of filtering purely server-side. /// </summary> public partial class DomainDataSourceFilteringControl : UserControl, IFilteringControl { // The main player here. DomainDataSource domainDataSource; // This is the name of the property that this column displays. private string dataMemberName; // This is the type of the property that this column displays. private Type dataMemberType; /// <summary> /// Identifies the <see cref="IsActive"/> dependency property. /// </summary> /// <remarks> /// The state of the filtering funnel (i.e. full or empty) is bound to this property. /// </remarks> public static readonly DependencyProperty IsActiveProperty = DependencyProperty.Register( "IsActive", typeof(bool), typeof(DomainDataSourceFilteringControl), new PropertyMetadata(false)); /// <summary> /// Gets or sets a value indicating whether the filtering is active. /// </summary> /// <remarks> /// Set this to true if you want to lit-up the filtering funnel. /// </remarks> public bool IsActive { get { return (bool)GetValue(IsActiveProperty); } set { SetValue(IsActiveProperty, value); } } /// <summary> /// Gets or sets the domain data source. /// We need this in order to work on its FilterDescriptors collection. /// </summary> /// <value>The domain data source.</value> public DomainDataSource DomainDataSource { get { return this.domainDataSource; } set { this.domainDataSource = value; } } public System.Windows.Data.FilterDescriptorCollection FilterDescriptors { get { return this.DomainDataSource.FilterDescriptors; } } public DomainDataSourceFilteringControl() { InitializeComponent(); } public void Prepare(GridViewBoundColumnBase column) { this.LayoutRoot.DataContext = this; if (this.DomainDataSource == null) { // Sorry, but we need a DomainDataSource. Can't do anything without it. return; } // This is the name of the property that this column displays. this.dataMemberName = column.GetDataMemberName(); // This is the type of the property that this column displays. // We need this in order to see which FilterOperators to feed to the combo-box column. this.dataMemberType = column.DataType; // We will use our magic Type extension method to see which operators are applicable for // this data type. You can go to the extension method body and see what it does. ((GridViewComboBoxColumn)this.filtersGrid.Columns["Operator"]).ItemsSource = this.dataMemberType.ApplicableFilterOperators(); // This is very nice as well. We will tell the Value column its data type. In this way // RadGridView will pick up the best editor according to the data type. For example, // if the data type of the value is DateTime, you will be editing it with a DatePicker. // Nice! ((GridViewDataColumn)this.filtersGrid.Columns["Value"]).DataType = this.dataMemberType; // Yet another nice feature. We will transfer the original DataFormatString (if any) to // the Value column. In this way if you have specified a DataFormatString for the original // column, you will see all filter values formatted accordingly. ((GridViewDataColumn)this.filtersGrid.Columns["Value"]).DataFormatString = column.DataFormatString; // This is important. Since our little filtersGrid will be bound to the entire collection // of this.domainDataSource.FilterDescriptors, we need to set a Telerik filter on the // grid so that it will display FilterDescriptor which are relevane to this column ONLY! Telerik.Windows.Data.FilterDescriptor columnFilter = new Telerik.Windows.Data.FilterDescriptor("PropertyPath" , Telerik.Windows.Data.FilterOperator.IsEqualTo , this.dataMemberName); this.filtersGrid.FilterDescriptors.Add(columnFilter); // We want to listen for this in order to activate and de-activate the UI funnel. this.filtersGrid.Items.CollectionChanged += this.OnFilterGridItemsCollectionChanged; } /// <summary> // Since the DomainDataSource is a little bit picky about adding uninitialized FilterDescriptors // to its collection, we will prepare each new instance with some default values and then // the user can change them later. Go to the event handler to see how we do this. /// </summary> void OnFilterGridAddingNewDataItem(object sender, GridViewAddingNewEventArgs e) { // We need to initialize the new instance with some values and let the user go on from here. System.Windows.Data.FilterDescriptor newFilter = new System.Windows.Data.FilterDescriptor(); // This is a must. It should know what member it is filtering on. newFilter.PropertyPath = this.dataMemberName; // Initialize it with one of the allowed operators. // TypeExtensions.ApplicableFilterOperators method for more info. newFilter.Operator = this.dataMemberType.ApplicableFilterOperators().First(); if (this.dataMemberType == typeof(DateTime)) { newFilter.Value.Value = DateTime.Now; } else if (this.dataMemberType == typeof(string)) { newFilter.Value.Value = "<enter text>"; } else if (this.dataMemberType.IsValueType) { // We need something non-null for all value types. newFilter.Value.Value = Activator.CreateInstance(this.dataMemberType); } // Let the user edit the new filter any way he/she likes. e.NewObject = newFilter; } void OnFilterGridItemsCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) { // We are active only if we have any filters define. In this case the filtering funnel will lit-up. this.IsActive = this.filtersGrid.Items.Count > 0; } private void OnApplyFiltersButtonClick(object sender, RoutedEventArgs e) { if (this.DomainDataSource.IsLoadingData) { return; } // Comment this if you want the popup to stay open after the button is clicked. this.ClosePopup(); // Since this.domainDataSource.AutoLoad is false, this will take into // account all filtering changes that the user has made since the last // Load() and pull the new data to the client. this.DomainDataSource.Load(); } private void OnClearFiltersButtonClick(object sender, RoutedEventArgs e) { if (this.DomainDataSource.IsLoadingData) { return; } // We want to remove ONLY those filters from the DomainDataSource // that this control is responsible for. this.DomainDataSource.FilterDescriptors .Where(fd => fd.PropertyPath == this.dataMemberName) // Only "our" filters. .ToList() .ForEach(fd => this.DomainDataSource.FilterDescriptors.Remove(fd)); // Bye-bye! // Comment this if you want the popup to stay open after the button is clicked. this.ClosePopup(); // After we did our housekeeping, get the new data to the client. this.DomainDataSource.Load(); } private void OnAddFilterButtonClick(object sender, RoutedEventArgs e) { if (this.DomainDataSource.IsLoadingData) { return; } // Let the user enter his/or her requirements for a new filter. this.filtersGrid.BeginInsert(); this.filtersGrid.UpdateLayout(); } private void OnRemoveFilterButtonClick(object sender, RoutedEventArgs e) { if (this.DomainDataSource.IsLoadingData) { return; } // Find the currently selected filter and destroy it. System.Windows.Data.FilterDescriptor filterToRemove = this.filtersGrid.SelectedItem as System.Windows.Data.FilterDescriptor; if (filterToRemove != null && this.DomainDataSource.FilterDescriptors.Contains(filterToRemove)) { this.DomainDataSource.FilterDescriptors.Remove(filterToRemove); } } private void ClosePopup() { System.Windows.Controls.Primitives.Popup popup = this.ParentOfType<System.Windows.Controls.Primitives.Popup>(); if (popup != null) { popup.IsOpen = false; } } } } Finally, we need to tell RadGridViews Columns to use this custom control instead of the default one. Here is how to do it: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes; using System.Windows.Data; using Telerik.Windows.Data; using Telerik.Windows.Controls; using Telerik.Windows.Controls.GridView; namespace PureServerSideFiltering { public partial class MainPage : UserControl { public MainPage() { InitializeComponent(); this.grid.AutoGeneratingColumn += this.OnGridAutoGeneratingColumn; // Uncomment this if you want the DomainDataSource to start pre-filtered. // You will notice how our custom filtering controls will correctly read this information, // populate their UI with the respective filters and lit-up the funnel to indicate that // filtering is active. Go ahead and try it. this.employeesDataSource.FilterDescriptors.Add(new System.Windows.Data.FilterDescriptor("Title", System.Windows.Data.FilterOperator.Contains, "Assistant")); this.employeesDataSource.FilterDescriptors.Add(new System.Windows.Data.FilterDescriptor("HireDate", System.Windows.Data.FilterOperator.IsGreaterThan, new DateTime(1998, 12, 31))); this.employeesDataSource.FilterDescriptors.Add(new System.Windows.Data.FilterDescriptor("HireDate", System.Windows.Data.FilterOperator.IsLessThanOrEqualTo, new DateTime(1999, 12, 31))); this.employeesDataSource.Load(); } /// <summary> /// First of all, we will need to replace the default filtering control /// of each column with out custom filtering control DomainDataSourceFilteringControl /// </summary> private void OnGridAutoGeneratingColumn(object sender, GridViewAutoGeneratingColumnEventArgs e) { GridViewBoundColumnBase dataColumn = e.Column as GridViewBoundColumnBase; if (dataColumn != null) { // We do not like ugly dates. if (dataColumn.DataType == typeof(DateTime)) { dataColumn.DataFormatString = "{0:d}"; // Short date pattern. // Notice how this format will be later transferred to the Value column // of the grid that we have inside the DomainDataSourceFilteringControl. } // Replace the default filtering control with our. dataColumn.FilteringControl = new DomainDataSourceFilteringControl() { // Let the control know about the DDS, after all it will work directly on it. DomainDataSource = this.employeesDataSource }; // Finally, lit-up the filtering funnel through the IsActive dependency property // in case there are some filters on the DDS that match our column member. string dataMemberName = dataColumn.GetDataMemberName(); dataColumn.FilteringControl.IsActive = this.employeesDataSource.FilterDescriptors .Where(fd => fd.PropertyPath == dataMemberName) .Count() > 0; } } } } The best part is that we are not only writing filters for the DomainDataSource we can read and load them. If the DomainDataSource has some pre-existing filters (like I have created in the code above), our control will read them and will populate its UI accordingly. Even the filtering funnel will light-up! Remember, the funnel is controlled by the IsActive property of our control. While this is just a basic implementation, the source code is absolutely yours and you can take it from here and extend it to match your specific business requirements. Below the main grid there is another debug grid. With its help you can monitor what filter descriptors are added and removed to the domain data source. Download Source Code. (You will have to have the AdventureWorks sample database installed on the default SQLExpress instance in order to run it.) Enjoy!Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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User Provisioning Tool for SQL Server 2008?

- by Rob Sanders

Yesterday I moved my machine from one domain to another - foolishly forgetting the implications for my local instance of SQL Server! Mixed Mode authentication is not enabled, and the only local account login has only "public" permissions. SQL Server 2005 Service Pack 2 had a tool called the User Provisioning Tool for Windows Vista (sqlprov.exe) which allowed you to add Domain Users to a local SQL 2005 instance (it doesn't work against SQL 2008 btw) - my question is.. is there a similar tool for SQL Server 2008 or am I going to have to do a reinstall? Also let me know if you think this belongs on StackOverflow

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C# Neural Networks with Encog

- by JoshReuben

Neural Networks · I recently read a book Introduction to Neural Networks for C# , by Jeff Heaton. http://www.amazon.com/Introduction-Neural-Networks-C-2nd/dp/1604390093/ref=sr_1_2?ie=UTF8&s=books&qid=1296821004&sr=8-2-spell. Not the 1st ANN book I've perused, but a nice revision. · Artificial Neural Networks (ANNs) are a mechanism of machine learning – see http://en.wikipedia.org/wiki/Artificial_neural_network , http://en.wikipedia.org/wiki/Category:Machine_learning · Problems Not Suited to a Neural Network Solution- Programs that are easily written out as flowcharts consisting of well-defined steps, program logic that is unlikely to change, problems in which you must know exactly how the solution was derived. · Problems Suited to a Neural Network – pattern recognition, classification, series prediction, and data mining. Pattern recognition - network attempts to determine if the input data matches a pattern that it has been trained to recognize. Classification - take input samples and classify them into fuzzy groups. · As far as machine learning approaches go, I thing SVMs are superior (see http://en.wikipedia.org/wiki/Support_vector_machine ) - a neural network has certain disadvantages in comparison: an ANN can be overtrained, different training sets can produce non-deterministic weights and it is not possible to discern the underlying decision function of an ANN from its weight matrix – they are black box. · In this post, I'm not going to go into internals (believe me I know them). An autoassociative network (e.g. a Hopfield network) will echo back a pattern if it is recognized. · Under the hood, there is very little maths. In a nutshell - Some simple matrix operations occur during training: the input array is processed (normalized into bipolar values of 1, -1) - transposed from input column vector into a row vector, these are subject to matrix multiplication and then subtraction of the identity matrix to get a contribution matrix. The dot product is taken against the weight matrix to yield a boolean match result. For backpropogation training, a derivative function is required. In learning, hill climbing mechanisms such as Genetic Algorithms and Simulated Annealing are used to escape local minima. For unsupervised training, such as found in Self Organizing Maps used for OCR, Hebbs rule is applied. · The purpose of this post is not to mire you in technical and conceptual details, but to show you how to leverage neural networks via an abstraction API - Encog Encog · Encog is a neural network API · Links to Encog: http://www.encog.org , http://www.heatonresearch.com/encog, http://www.heatonresearch.com/forum · Encog requires .Net 3.5 or higher – there is also a Silverlight version. Third-Party Libraries – log4net and nunit. · Encog supports feedforward, recurrent, self-organizing maps, radial basis function and Hopfield neural networks. · Encog neural networks, and related data, can be stored in .EG XML files. · Encog Workbench allows you to edit, train and visualize neural networks. The Encog Workbench can generate code. Synapses and layers · the primary building blocks - Almost every neural network will have, at a minimum, an input and output layer. In some cases, the same layer will function as both input and output layer. · To adapt a problem to a neural network, you must determine how to feed the problem into the input layer of a neural network, and receive the solution through the output layer of a neural network. · The Input Layer - For each input neuron, one double value is stored. An array is passed as input to a layer. Encog uses the interface INeuralData to hold these arrays. The class BasicNeuralData implements the INeuralData interface. Once the neural network processes the input, an INeuralData based class will be returned from the neural network's output layer. · convert a double array into an INeuralData object : INeuralData data = new BasicNeuralData(= new double[10]); · the Output Layer- The neural network outputs an array of doubles, wraped in a class based on the INeuralData interface. · The real power of a neural network comes from its pattern recognition capabilities. The neural network should be able to produce the desired output even if the input has been slightly distorted. · Hidden Layers– optional. between the input and output layers. very much a “black box”. If the structure of the hidden layer is too simple it may not learn the problem. If the structure is too complex, it will learn the problem but will be very slow to train and execute. Some neural networks have no hidden layers. The input layer may be directly connected to the output layer. Further, some neural networks have only a single layer. A single layer neural network has the single layer self-connected. · connections, called synapses, contain individual weight matrixes. These values are changed as the neural network learns. Constructing a Neural Network · the XOR operator is a frequent “first example” -the “Hello World” application for neural networks. · The XOR Operator- only returns true when both inputs differ. 0 XOR 0 = 0 1 XOR 0 = 1 0 XOR 1 = 1 1 XOR 1 = 0 · Structuring a Neural Network for XOR - two inputs to the XOR operator and one output. · input: 0.0,0.0 1.0,0.0 0.0,1.0 1.0,1.0 · Expected output: 0.0 1.0 1.0 0.0 · A Perceptron - a simple feedforward neural network to learn the XOR operator. · Because the XOR operator has two inputs and one output, the neural network will follow suit. Additionally, the neural network will have a single hidden layer, with two neurons to help process the data. The choice for 2 neurons in the hidden layer is arbitrary, and often comes down to trial and error. · Neuron Diagram for the XOR Network · · The Encog workbench displays neural networks on a layer-by-layer basis. · Encog Layer Diagram for the XOR Network: · Create a BasicNetwork - Three layers are added to this network. the FinalizeStructure method must be called to inform the network that no more layers are to be added. The call to Reset randomizes the weights in the connections between these layers. var network = new BasicNetwork(); network.AddLayer(new BasicLayer(2)); network.AddLayer(new BasicLayer(2)); network.AddLayer(new BasicLayer(1)); network.Structure.FinalizeStructure(); network.Reset(); · Neural networks frequently start with a random weight matrix. This provides a starting point for the training methods. These random values will be tested and refined into an acceptable solution. However, sometimes the initial random values are too far off. Sometimes it may be necessary to reset the weights again, if training is ineffective. These weights make up the long-term memory of the neural network. Additionally, some layers have threshold values that also contribute to the long-term memory of the neural network. Some neural networks also contain context layers, which give the neural network a short-term memory as well. The neural network learns by modifying these weight and threshold values. · Now that the neural network has been created, it must be trained. Training a Neural Network · construct a INeuralDataSet object - contains the input array and the expected output array (of corresponding range). Even though there is only one output value, we must still use a two-dimensional array to represent the output. public static double[][] XOR_INPUT ={ new double[2] { 0.0, 0.0 }, new double[2] { 1.0, 0.0 }, new double[2] { 0.0, 1.0 }, new double[2] { 1.0, 1.0 } }; public static double[][] XOR_IDEAL = { new double[1] { 0.0 }, new double[1] { 1.0 }, new double[1] { 1.0 }, new double[1] { 0.0 } }; INeuralDataSet trainingSet = new BasicNeuralDataSet(XOR_INPUT, XOR_IDEAL); · Training is the process where the neural network's weights are adjusted to better produce the expected output. Training will continue for many iterations, until the error rate of the network is below an acceptable level. Encog supports many different types of training. Resilient Propagation (RPROP) - general-purpose training algorithm. All training classes implement the ITrain interface. The RPROP algorithm is implemented by the ResilientPropagation class. Training the neural network involves calling the Iteration method on the ITrain class until the error is below a specific value. The code loops through as many iterations, or epochs, as it takes to get the error rate for the neural network to be below 1%. Once the neural network has been trained, it is ready for use. ITrain train = new ResilientPropagation(network, trainingSet); for (int epoch=0; epoch < 10000; epoch++) { train.Iteration(); Debug.Print("Epoch #" + epoch + " Error:" + train.Error); if (train.Error > 0.01) break; } Executing a Neural Network · Call the Compute method on the BasicNetwork class. Console.WriteLine("Neural Network Results:"); foreach (INeuralDataPair pair in trainingSet) { INeuralData output = network.Compute(pair.Input); Console.WriteLine(pair.Input[0] + "," + pair.Input[1] + ", actual=" + output[0] + ",ideal=" + pair.Ideal[0]); } · The Compute method accepts an INeuralData class and also returns a INeuralData object. Neural Network Results: 0.0,0.0, actual=0.002782538818034049,ideal=0.0 1.0,0.0, actual=0.9903741937121177,ideal=1.0 0.0,1.0, actual=0.9836807956566187,ideal=1.0 1.0,1.0, actual=0.0011646072586172778,ideal=0.0 · the network has not been trained to give the exact results. This is normal. Because the network was trained to 1% error, each of the results will also be within generally 1% of the expected value.

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500 internal server error on certain page after a few hours

- by Brian Leach

I am getting a 500 Internal Server Error on a certain page of my site after a few hours of being up. I restart uWSGI instance with uwsgi --ini /home/metheuser/webapps/ers_portal/ers_portal_uwsgi.ini and it works again for a few hours. The rest of the site seems to be working. When I navigate to my_table, I am directed to the login page. But, I get the 500 error on my table page on login. I followed the instructions here to set up my nginx and uwsgi configs. That is, I have ers_portal_nginx.conf located i my app folder that is symlinked to /etc/nginx/conf.d/. I start my uWSGI "instance" (not sure what exactly to call it) in a Screen instance as mentioned above, with the .ini file located in my app folder My ers_portal_nginx.conf: server { listen 80; server_name www.mydomain.com; location / { try_files $uri @app; } location @app { include uwsgi_params; uwsgi_pass unix:/home/metheuser/webapps/ers_portal/run_web_uwsgi.sock; } } My ers_portal_uwsgi.ini: [uwsgi] #user info uid = metheuser gid = ers_group #application's base folder base = /home/metheuser/webapps/ers_portal #python module to import app = run_web module = %(app) home = %(base)/ers_portal_venv pythonpath = %(base) #socket file's location socket = /home/metheuser/webapps/ers_portal/%n.sock #permissions for the socket file chmod-socket = 666 #uwsgi varible only, does not relate to your flask application callable = app #location of log files logto = /home/metheuser/webapps/ers_portal/logs/%n.log Relevant parts of my views.py data_modification_time = None data = None def reload_data(): global data_modification_time, data, sites, column_names filename = '/home/metheuser/webapps/ers_portal/app/static/' + ec.dd_filename mtime = os.stat(filename).st_mtime if data_modification_time != mtime: data_modification_time = mtime with open(filename) as f: data = pickle.load(f) return data @a bunch of authentication stuff... @app.route('/') @app.route('/index') def index(): return render_template("index.html", title = 'Main',) @app.route('/login', methods = ['GET', 'POST']) def login(): login stuff... @app.route('/my_table') @login_required def my_table(): print 'trying to access data table...' data = reload_data() return render_template("my_table.html", title = "Rundata Viewer", sts = sites, cn = column_names, data = data) # dictionary of data I installed nginx via yum as described here (yesterday) I am using uWSGI installed in my venv via pip I am on CentOS 6 My uwsgi log shows: Wed Jun 11 17:20:01 2014 - uwsgi_response_writev_headers_and_body_do(): Broken pipe [core/writer.c line 287] during GET /whm-server-status (127.0.0.1) IOError: write error [pid: 9586|app: 0|req: 135/135] 127.0.0.1 () {24 vars in 292 bytes} [Wed Jun 11 17:20:01 2014] GET /whm-server-status => generated 0 bytes in 3 msecs (HTTP/1.0 404) 2 headers in 0 bytes (0 switches on core 0) When its working, the print statement in the views "my_table" route prints into the log file. But not once it stops working. Any ideas?

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Advantages of SQL Backup Pro

- by Grant Fritchey

Getting backups of your databases in place is a fundamental issue for protection of the business. Yes, I said business, not data, not databases, but business. Because of a lack of good, tested, backups, companies have gone completely out of business or suffered traumatic financial loss. That’s just a simple fact (outlined with a few examples here). So you want to get backups right. That’s a big part of why we make Red Gate SQL Backup Pro work the way it does. Yes, you could just use native backups, but you’ll be missing a few advantages that we provide over and above what you get out of the box from Microsoft. Let’s talk about them. Guidance If you’re a hard-core DBA with 20+ years of experience on every version of SQL Server and several other data platforms besides, you may already know what you need in order to get a set of tested backups in place. But, if you’re not, maybe a little help would be a good thing. To set up backups for your servers, we supply a wizard that will step you through the entire process. It will also act to guide you down good paths. For example, if your databases are in Full Recovery, you should set up transaction log backups to run on a regular basis. When you choose a transaction log backup from the Backup Type you’ll see that only those databases that are in Full Recovery will be listed: This makes it very easy to be sure you have a log backup set up for all the databases you should and none of the databases where you won’t be able to. There are other examples of guidance throughout the product. If you have the responsibility of managing backups but very little knowledge or time, we can help you out. Throughout the software you’ll notice little green question marks. You can see two in the screen above and more in each of the screens in other topics below this one. Clicking on these will open a window with additional information about the topic in question which should help to guide you through some of the tougher decisions you may have to make while setting up your backup jobs. Here’s an example: Backup Copies As a part of the wizard you can choose to make a copy of your backup on your network. This process runs as part of the Red Gate SQL Backup engine. It will copy your backup, after completing the backup so it doesn’t cause any additional blocking or resource use within the backup process, to the network location you define. Creating a copy acts as a mechanism of protection for your backups. You can then backup that copy or do other things with it, all without affecting the original backup file. This requires either an additional backup or additional scripting to get it done within the native Microsoft backup engine. Offsite Storage Red Gate offers you the ability to immediately copy your backup to the cloud as a further, off-site, protection of your backups. It’s a service we provide and expose through the Backup wizard. Your backup will complete first, just like with the network backup copy, then an asynchronous process will copy that backup to cloud storage. Again, this is built right into the wizard or even the command line calls to SQL Backup, so it’s part a single process within your system. With native backup you would need to write additional scripts, possibly outside of T-SQL, to make this happen. Before you can use this with your backups you’ll need to do a little setup, but it’s built right into the product to get this done. You’ll be directed to the web site for our hosted storage where you can set up an account. Compression If you have SQL Server 2008 Enterprise, or you’re on SQL Server 2008R2 or greater and you have a Standard or Enterprise license, then you have backup compression. It’s built right in and works well. But, if you need even more compression then you might want to consider Red Gate SQL Backup Pro. We offer four levels of compression within the product. This means you can get a little compression faster, or you can just sacrifice some CPU time and get even more compression. You decide. For just a simple example I backed up AdventureWorks2012 using both methods of compression. The resulting file from native was 53mb. Our file was 33mb. That’s a file that is smaller by 38%, not a small number when we start talking gigabytes. We even provide guidance here to help you determine which level of compression would be right for you and your system: So for this test, if you wanted maximum compression with minimum CPU use you’d probably want to go with Level 2 which gets you almost as much compression as Level 3 but will use fewer resources. And that compression is still better than the native one by 10%. Restore Testing Backups are vital. But, a backup is just a file until you restore it. How do you know that you can restore that backup? Of course, you’ll use CHECKSUM to validate that what was read from disk during the backup process is what gets written to the backup file. You’ll also use VERIFYONLY to check that the backup header and the checksums on the backup file are valid. But, this doesn’t do a complete test of the backup. The only complete test is a restore. So, what you really need is a process that tests your backups. This is something you’ll have to schedule separately from your backups, but we provide a couple of mechanisms to help you out here. First, when you create a backup schedule, all done through our wizard which gives you as much guidance as you get when running backups, you get the option of creating a reminder to create a job to test your restores. You can enable this or disable it as you choose when creating your scheduled backups. Once you’re ready to schedule test restores for your databases, we have a wizard for this as well. After you choose the databases and restores you want to test, all configurable for automation, you get to decide if you’re going to restore to a specified copy or to the original database: If you’re doing your tests on a new server (probably the best choice) you can just overwrite the original database if it’s there. If not, you may want to create a new database each time you test your restores. Another part of validating your backups is ensuring that they can pass consistency checks. So we have DBCC built right into the process. You can even decide how you want DBCC run, which error messages to include, limit or add to the checks being run. With this you could offload some DBCC checks from your production system so that you only run the physical checks on your production box, but run the full check on this backup. That makes backup testing not just a general safety process, but a performance enhancer as well: Finally, assuming the tests pass, you can delete the database, leave it in place, or delete it regardless of the tests passing. All this is automated and scheduled through the SQL Agent job on your servers. Running your databases through this process will ensure that you don’t just have backups, but that you have tested backups. Single Point of Management If you have more than one server to maintain, getting backups setup could be a tedious process. But, with Red Gate SQL Backup Pro you can connect to multiple servers and then manage all your databases and all your servers backups from a single location. You’ll be able to see what is scheduled, what has run successfully and what has failed, all from a single interface without having to connect to different servers. Log Shipping Wizard If you want to set up log shipping as part of a disaster recovery process, it can frequently be a pain to get configured correctly. We supply a wizard that will walk you through every step of the process including setting up alerts so you’ll know should your log shipping fail. Summary You want to get your backups right. As outlined above, Red Gate SQL Backup Pro will absolutely help you there. We supply a number of processes and functionalities above and beyond what you get with SQL Server native. Plus, with our guidance, hints and reminders, you will get your backups set up in a way that protects your business.

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What code smell best describes this code?

- by Paul Stovell

Suppose you have this code in a class: private DataContext _context; public Customer[] GetCustomers() { GetContext(); return _context.Customers.ToArray(); } public Order[] GetOrders() { GetContext(); return _context.Customers.ToArray(); } // For the sake of this example, a new DataContext is *required* // for every public method call private void GetContext() { if (_context != null) { _context.Dispose(); } _context = new DataContext(); } This code isn't thread-safe - if two calls to GetOrders/GetCustomers are made at the same time from different threads, they may end up using the same context, or the context could be disposed while being used. Even if this bug didn't exist, however, it still "smells" like bad code. A much better design would be for GetContext to always return a new instance of DataContext and to get rid of the private field, and to dispose of the instance when done. Changing from an inappropriate private field to a local variable feels like a better solution. I've looked over the code smell lists and can't find one that describes this. In the past I've thought of it as temporal coupling, but the Wikipedia description suggests that's not the term: Temporal coupling When two actions are bundled together into one module just because they happen to occur at the same time. This page discusses temporal coupling, but the example is the public API of a class, while my question is about the internal design. Does this smell have a name? Or is it simply "buggy code"?

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How bad is it to use display: none in CSS?

- by Andy

I've heard many times that it's bad to use display: none for SEO reasons, as it could be an attempt to push in irrelevant popular keywords. A few questions: Is that still received wisdom? Does it make a difference if you're only hiding a single word, or perhaps a single character? If you should avoid any use of it, what are the preferred techniques for hiding (in situations where you need it to become visible again on certain conditions)? Some references I've found so far: Matt Cutts from 2005 in a comment If you're straight-out using CSS to hide text, don't be surprised if that is called spam. I'm not saying that mouseovers or DHTML text or have-a-logo-but-also-have-text is spam; I answered that last one at a conference when I said "imagine how it would look to a visitor, a competitor, or someone checking out a spam report. If you show your company's name and it's Expo Markers instead of an Expo Markers logo, you should be fine. If the text you decide to show is 'Expo Markers cheap online discount buy online Expo Markers sale ...' then I would be more cautious, because that can look bad." And in another comment on the same article We can flag text that appears to be hidden using CSS at Google. To date we have not algorithmically removed sites for doing that. We try hard to avoid throwing babies out with bathwater. (My emphasis) Eric Enge said in 2008 The legitimate use of this technique is so prevalent that I would rarely expect search engines to penalize a site for using the display: none attribute. It’s just very difficult to implement an algorithm that could truly ferret out whether the particular use of display: none is meant to deceive the search engines or not. Thanks in advance, Andy

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SQL Server – Learning SQL Server Performance: Indexing Basics – Interview of Vinod Kumar by Pinal Dave

- by pinaldave

Recently I just wrote a blog post on about Learning SQL Server Performance: Indexing Basics and I received lots of request that if we can share some insight into the course. Every single time when Performance is discussed, Indexes are mentioned along with it. In recent times, data and application complexity is continuously growing. The demand for faster query response, performance, and scalability by organizations is increasing and developers and DBAs need to now write efficient code to achieve this. When we developed the course – we made sure that this course remains practical and demo heavy instead of just theories on this subject. Vinod Kumar and myself we often thought about this and realized that practical understanding of the indexes is very important. One can not master every single aspects of the index. However there are some minimum expertise one should gain if performance is one of the concern. Here is 200 seconds interview of Vinod Kumar I took right after completing the course. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Index, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology, Video

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Loading a Template From a User Control

- by Ricardo Peres

What if you wanted to load a template (ITemplate property) from an external user control (.ascx) file? Yes, it is possible; there are a number of ways to do this, the one I'll talk about here is through a type converter. You need to apply a TypeConverterAttribute to your ITemplate property where you specify a custom type converter that does the job. This type converter relies on InstanceDescriptor. Here is the code for it: public class TemplateTypeConverter: TypeConverter { public override Boolean CanConvertFrom(ITypeDescriptorContext context, Type sourceType) { return ((sourceType == typeof(String)) || (base.CanConvertFrom(context, sourceType) == true)); } public override Boolean CanConvertTo(ITypeDescriptorContext context, Type destinationType) { return ((destinationType == typeof(InstanceDescriptor)) || (base.CanConvertTo(context, destinationType) == true)); } public override Object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, Object value, Type destinationType) { if (destinationType == typeof(InstanceDescriptor)) { Object objectFactory = value.GetType().GetField("_objectFactory", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(value); Object builtType = objectFactory.GetType().BaseType.GetField("_builtType", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(objectFactory); MethodInfo loadTemplate = typeof(TemplateTypeConverter).GetMethod("LoadTemplate"); return (new InstanceDescriptor(loadTemplate, new Object [] { "~/" + (builtType as Type).Name.Replace('_', '/').Replace("/ascx", ".ascx") })); } return base.ConvertTo(context, culture, value, destinationType); } public static ITemplate LoadTemplate(String virtualPath) { using (Page page = new Page()) { return (page.LoadTemplate(virtualPath)); } } } And, on your control: public class MyControl: Control { [Browsable(false)] [TypeConverter(typeof(TemplateTypeConverter))] public ITemplate Template { get; set; } } This allows the following declaration: Hope this helps! SyntaxHighlighter.config.clipboardSwf = 'http://alexgorbatchev.com/pub/sh/2.0.320/scripts/clipboard.swf'; SyntaxHighlighter.brushes.CSharp.aliases = ['c#', 'c-sharp', 'csharp']; SyntaxHighlighter.brushes.Xml.aliases = ['xml']; SyntaxHighlighter.all();

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ASP.NET MVC Validation Complete

- by Ricardo Peres

OK, so let’s talk about validation. Most people are probably familiar with the out of the box validation attributes that MVC knows about, from the System.ComponentModel.DataAnnotations namespace, such as EnumDataTypeAttribute, RequiredAttribute, StringLengthAttribute, RangeAttribute, RegularExpressionAttribute and CompareAttribute from the System.Web.Mvc namespace. All of these validators inherit from ValidationAttribute and perform server as well as client-side validation. In order to use them, you must include the JavaScript files MicrosoftMvcValidation.js, jquery.validate.js or jquery.validate.unobtrusive.js, depending on whether you want to use Microsoft’s own library or jQuery. No significant difference exists, but jQuery is more extensible. You can also create your own attribute by inheriting from ValidationAttribute, but, if you want to have client-side behavior, you must also implement IClientValidatable (all of the out of the box validation attributes implement it) and supply your own JavaScript validation function that mimics its server-side counterpart. Of course, you must reference the JavaScript file where the declaration function is. Let’s see an example, validating even numbers. First, the validation attribute: 1: [Serializable] 2: [AttributeUsage(AttributeTargets.Property, AllowMultiple = false, Inherited = true)] 3: public class IsEvenAttribute : ValidationAttribute, IClientValidatable 4: { 5: protected override ValidationResult IsValid(Object value, ValidationContext validationContext) 6: { 7: Int32 v = Convert.ToInt32(value); 8: 9: if (v % 2 == 0) 10: { 11: return (ValidationResult.Success); 12: } 13: else 14: { 15: return (new ValidationResult("Value is not even")); 16: } 17: } 18: 19: #region IClientValidatable Members 20: 21: public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context) 22: { 23: yield return (new ModelClientValidationRule() { ValidationType = "iseven", ErrorMessage = "Value is not even" }); 24: } 25: 26: #endregion 27: } The iseven validation function is declared like this in JavaScript, using jQuery validation: 1: jQuery.validator.addMethod('iseven', function (value, element, params) 2: { 3: return (true); 4: return ((parseInt(value) % 2) == 0); 5: }); 6: 7: jQuery.validator.unobtrusive.adapters.add('iseven', [], function (options) 8: { 9: options.rules['iseven'] = options.params; 10: options.messages['iseven'] = options.message; 11: }); Do keep in mind that this is a simple example, for example, we are not using parameters, which may be required for some more advanced scenarios. As a side note, if you implement a custom validator that also requires a JavaScript function, you’ll probably want them together. One way to achieve this is by including the JavaScript file as an embedded resource on the same assembly where the custom attribute is declared. You do this by having its Build Action set as Embedded Resource inside Visual Studio: Then you have to declare an attribute at assembly level, perhaps in the AssemblyInfo.cs file: 1: [assembly: WebResource("SomeNamespace.IsEven.js", "text/javascript")] In your views, if you want to include a JavaScript file from an embedded resource you can use this code: 1: public static class UrlExtensions 2: { 3: private static readonly MethodInfo getResourceUrlMethod = typeof(AssemblyResourceLoader).GetMethod("GetWebResourceUrlInternal", BindingFlags.NonPublic | BindingFlags.Static); 4: 5: public static IHtmlString Resource<TType>(this UrlHelper url, String resourceName) 6: { 7: return (Resource(url, typeof(TType).Assembly.FullName, resourceName)); 8: } 9: 10: public static IHtmlString Resource(this UrlHelper url, String assemblyName, String resourceName) 11: { 12: String resourceUrl = getResourceUrlMethod.Invoke(null, new Object[] { Assembly.Load(assemblyName), resourceName, false, false, null }).ToString(); 13: return (new HtmlString(resourceUrl)); 14: } 15: } And on the view: 1: <script src="<%: this.Url.Resource("SomeAssembly", "SomeNamespace.IsEven.js") %>" type="text/javascript"></script> Then there’s the CustomValidationAttribute. It allows externalizing your validation logic to another class, so you have to tell which type and method to use. The method can be static as well as instance, if it is instance, the class cannot be abstract and must have a public parameterless constructor. It can be applied to a property as well as a class. It does not, however, support client-side validation. Let’s see an example declaration: 1: [CustomValidation(typeof(ProductValidator), "OnValidateName")] 2: public String Name 3: { 4: get; 5: set; 6: } The validation method needs this signature: 1: public static ValidationResult OnValidateName(String name) 2: { 3: if ((String.IsNullOrWhiteSpace(name) == false) && (name.Length <= 50)) 4: { 5: return (ValidationResult.Success); 6: } 7: else 8: { 9: return (new ValidationResult(String.Format("The name has an invalid value: {0}", name), new String[] { "Name" })); 10: } 11: } Note that it can be either static or instance and it must return a ValidationResult-derived class. ValidationResult.Success is null, so any non-null value is considered a validation error. The single method argument must match the property type to which the attribute is attached to or the class, in case it is applied to a class: 1: [CustomValidation(typeof(ProductValidator), "OnValidateProduct")] 2: public class Product 3: { 4: } The signature must thus be: 1: public static ValidationResult OnValidateProduct(Product product) 2: { 3: } Continuing with attribute-based validation, another possibility is RemoteAttribute. This allows specifying a controller and an action method just for performing the validation of a property or set of properties. This works in a client-side AJAX way and it can be very useful. Let’s see an example, starting with the attribute declaration and proceeding to the action method implementation: 1: [Remote("Validate", "Validation")] 2: public String Username 3: { 4: get; 5: set; 6: } The controller action method must contain an argument that can be bound to the property: 1: public ActionResult Validate(String username) 2: { 3: return (this.Json(true, JsonRequestBehavior.AllowGet)); 4: } If in your result JSON object you include a string instead of the true value, it will consider it as an error, and the validation will fail. This string will be displayed as the error message, if you have included it in your view. You can also use the remote validation approach for validating your entire entity, by including all of its properties as included fields in the attribute and having an action method that receives an entity instead of a single property: 1: [Remote("Validate", "Validation", AdditionalFields = "Price")] 2: public String Name 3: { 4: get; 5: set; 6: } 7: 8: public Decimal Price 9: { 10: get; 11: set; 12: } The action method will then be: 1: public ActionResult Validate(Product product) 2: { 3: return (this.Json("Product is not valid", JsonRequestBehavior.AllowGet)); 4: } Only the property to which the attribute is applied and the additional properties referenced by the AdditionalFields will be populated in the entity instance received by the validation method. The same rule previously stated applies, if you return anything other than true, it will be used as the validation error message for the entity. The remote validation is triggered automatically, but you can also call it explicitly. In the next example, I am causing the full entity validation, see the call to serialize(): 1: function validate() 2: { 3: var form = $('form'); 4: var data = form.serialize(); 5: var url = '<%: this.Url.Action("Validation", "Validate") %>'; 6: 7: var result = $.ajax 8: ( 9: { 10: type: 'POST', 11: url: url, 12: data: data, 13: async: false 14: } 15: ).responseText; 16: 17: if (result) 18: { 19: //error 20: } 21: } Finally, by implementing IValidatableObject, you can implement your validation logic on the object itself, that is, you make it self-validatable. This will only work server-side, that is, the ModelState.IsValid property will be set to false on the controller’s action method if the validation in unsuccessful. Let’s see how to implement it: 1: public class Product : IValidatableObject 2: { 3: public String Name 4: { 5: get; 6: set; 7: } 8: 9: public Decimal Price 10: { 11: get; 12: set; 13: } 14: 15: #region IValidatableObject Members 16: 17: public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) 18: { 19: if ((String.IsNullOrWhiteSpace(this.Name) == true) || (this.Name.Length > 50)) 20: { 21: yield return (new ValidationResult(String.Format("The name has an invalid value: {0}", this.Name), new String[] { "Name" })); 22: } 23: 24: if ((this.Price <= 0) || (this.Price > 100)) 25: { 26: yield return (new ValidationResult(String.Format("The price has an invalid value: {0}", this.Price), new String[] { "Price" })); 27: } 28: } 29: 30: #endregion 31: } The errors returned will be matched against the model properties through the MemberNames property of the ValidationResult class and will be displayed in their proper labels, if present on the view. On the controller action method you can check for model validity by looking at ModelState.IsValid and you can get actual error messages and related properties by examining all of the entries in the ModelState dictionary: 1: Dictionary<String, String> errors = new Dictionary<String, String>(); 2: 3: foreach (KeyValuePair<String, ModelState> keyValue in this.ModelState) 4: { 5: String key = keyValue.Key; 6: ModelState modelState = keyValue.Value; 7: 8: foreach (ModelError error in modelState.Errors) 9: { 10: errors[key] = error.ErrorMessage; 11: } 12: } And these are the ways to perform date validation in ASP.NET MVC. Don’t forget to use them!

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