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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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  • Oracle UCM GET_SEARCH_RESULTS service with full text search

    - by Lyudmil Pelov
    Newly I was working on portlet which should be able to do full text search through the UCM documents and I was experimenting with the Ridc and also with the CIS API's. There are some ticks you may take care of, for example using quotes is a very spacial case and most of situations UCM will throw an exception if you not use them well. So during my tests I was able to develop one solution which works very well for me doing full text search and here is it: final IdcClientManager idcManager = new IdcClientManager(); final IdcClient idcClient = idcManager.createClient("idc://127.0.0.1:4444"); final IdcContext idcContext = new IdcContext("sysadmin"); final DataBinder binder = idcClient.createBinder(); // populate the binder with the parameters binder.putLocal ("IdcService", "GET_SEARCH_RESULTS"); binder.putLocal ("QueryText", "dDocFullText <substring> <qsch>"+yourSearchWordOrWords+"</qsch>");  binder.putLocal ("SearchEngineName", "databasefulltext"); binder.putLocal ("ResultCount", "20"); // execute the request ServiceResponse response = idcClient.sendRequest (idcContext, binder); // get the binder DataBinder serverBinder = response.getResponseAsBinder (); DataResultSet resultSet = serverBinder.getResultSet ("SearchResults"); // loop over the results for (DataObject dataObject : resultSet.getRows ()) { System.out.println ("Title is: " + dataObject.get ("dDocTitle")); System.out.println ("Author is: " + dataObject.get ("dDocAuthor")); }Nothing special so far except the line which declares the full text search. To be able to proceed with the full text search you have to use dDocFullText attribute inside the search query. The tag <substring> is the same as 'like'. Also you have to put your searching string or words in quotes which could be a problem sometime, so I used the tag <qsch>. Using this tag you can have quotes now inside you searching string without to break the code and get parsing exceptions.To be able to test the example, you do have to enable full text search inside UCM. To do this follow the steps for example from this blog here and then re-index the documents in UCM.There is also one very nice article about how to define UCM queries if want to replace the full text search with something more specific, you can read this article from Kyle's Blog here.

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  • Scrum in 5 Minutes

    - by Stephen.Walther
    The goal of this blog entry is to explain the basic concepts of Scrum in less than five minutes. You learn how Scrum can help a team of developers to successfully complete a complex software project. Product Backlog and the Product Owner Imagine that you are part of a team which needs to create a new website – for example, an e-commerce website. You have an overwhelming amount of work to do. You need to build (or possibly buy) a shopping cart, install an SSL certificate, create a product catalog, create a Facebook page, and at least a hundred other things that you have not thought of yet. According to Scrum, the first thing you should do is create a list. Place the highest priority items at the top of the list and the lower priority items lower in the list. For example, creating the shopping cart and buying the domain name might be high priority items and creating a Facebook page might be a lower priority item. In Scrum, this list is called the Product Backlog. How do you prioritize the items in the Product Backlog? Different stakeholders in the project might have different priorities. Gary, your division VP, thinks that it is crucial that the e-commerce site has a mobile app. Sally, your direct manager, thinks taking advantage of new HTML5 features is much more important. Multiple people are pulling you in different directions. According to Scrum, it is important that you always designate one person, and only one person, as the Product Owner. The Product Owner is the person who decides what items should be added to the Product Backlog and the priority of the items in the Product Backlog. The Product Owner could be the customer who is paying the bills, the project manager who is responsible for delivering the project, or a customer representative. The critical point is that the Product Owner must always be a single person and that single person has absolute authority over the Product Backlog. Sprints and the Sprint Backlog So now the developer team has a prioritized list of items and they can start work. The team starts implementing the first item in the Backlog — the shopping cart — and the team is making good progress. Unfortunately, however, half-way through the work of implementing the shopping cart, the Product Owner changes his mind. The Product Owner decides that it is much more important to create the product catalog before the shopping cart. With some frustration, the team switches their developmental efforts to focus on implementing the product catalog. However, part way through completing this work, once again the Product Owner changes his mind about the highest priority item. Getting work done when priorities are constantly shifting is frustrating for the developer team and it results in lower productivity. At the same time, however, the Product Owner needs to have absolute authority over the priority of the items which need to get done. Scrum solves this conflict with the concept of Sprints. In Scrum, a developer team works in Sprints. At the beginning of a Sprint the developers and the Product Owner agree on the items from the backlog which they will complete during the Sprint. This subset of items from the Product Backlog becomes the Sprint Backlog. During the Sprint, the Product Owner is not allowed to change the items in the Sprint Backlog. In other words, the Product Owner cannot shift priorities on the developer team during the Sprint. Different teams use Sprints of different lengths such as one month Sprints, two-week Sprints, and one week Sprints. For high-stress, time critical projects, teams typically choose shorter sprints such as one week sprints. For more mature projects, longer one month sprints might be more appropriate. A team can pick whatever Sprint length makes sense for them just as long as the team is consistent. You should pick a Sprint length and stick with it. Daily Scrum During a Sprint, the developer team needs to have meetings to coordinate their work on completing the items in the Sprint Backlog. For example, the team needs to discuss who is working on what and whether any blocking issues have been discovered. Developers hate meetings (well, sane developers hate meetings). Meetings take developers away from their work of actually implementing stuff as opposed to talking about implementing stuff. However, a developer team which never has meetings and never coordinates their work also has problems. For example, Fred might get stuck on a programming problem for days and never reach out for help even though Tom (who sits in the cubicle next to him) has already solved the very same problem. Or, both Ted and Fred might have started working on the same item from the Sprint Backlog at the same time. In Scrum, these conflicting needs – limiting meetings but enabling team coordination – are resolved with the idea of the Daily Scrum. The Daily Scrum is a meeting for coordinating the work of the developer team which happens once a day. To keep the meeting short, each developer answers only the following three questions: 1. What have you done since yesterday? 2. What do you plan to do today? 3. Any impediments in your way? During the Daily Scrum, developers are not allowed to talk about issues with their cat, do demos of their latest work, or tell heroic stories of programming problems overcome. The meeting must be kept short — typically about 15 minutes. Issues which come up during the Daily Scrum should be discussed in separate meetings which do not involve the whole developer team. Stories and Tasks Items in the Product or Sprint Backlog – such as building a shopping cart or creating a Facebook page – are often referred to as User Stories or Stories. The Stories are created by the Product Owner and should represent some business need. Unlike the Product Owner, the developer team needs to think about how a Story should be implemented. At the beginning of a Sprint, the developer team takes the Stories from the Sprint Backlog and breaks the stories into tasks. For example, the developer team might take the Create a Shopping Cart story and break it into the following tasks: · Enable users to add and remote items from shopping cart · Persist the shopping cart to database between visits · Redirect user to checkout page when Checkout button is clicked During the Daily Scrum, members of the developer team volunteer to complete the tasks required to implement the next Story in the Sprint Backlog. When a developer talks about what he did yesterday or plans to do tomorrow then the developer should be referring to a task. Stories are owned by the Product Owner and a story is all about business value. In contrast, the tasks are owned by the developer team and a task is all about implementation details. A story might take several days or weeks to complete. A task is something which a developer can complete in less than a day. Some teams get lazy about breaking stories into tasks. Neglecting to break stories into tasks can lead to “Never Ending Stories” If you don’t break a story into tasks, then you can’t know how much of a story has actually been completed because you don’t have a clear idea about the implementation steps required to complete the story. Scrumboard During the Daily Scrum, the developer team uses a Scrumboard to coordinate their work. A Scrumboard contains a list of the stories for the current Sprint, the tasks associated with each Story, and the state of each task. The developer team uses the Scrumboard so everyone on the team can see, at a glance, what everyone is working on. As a developer works on a task, the task moves from state to state and the state of the task is updated on the Scrumboard. Common task states are ToDo, In Progress, and Done. Some teams include additional task states such as Needs Review or Needs Testing. Some teams use a physical Scrumboard. In that case, you use index cards to represent the stories and the tasks and you tack the index cards onto a physical board. Using a physical Scrumboard has several disadvantages. A physical Scrumboard does not work well with a distributed team – for example, it is hard to share the same physical Scrumboard between Boston and Seattle. Also, generating reports from a physical Scrumboard is more difficult than generating reports from an online Scrumboard. Estimating Stories and Tasks Stakeholders in a project, the people investing in a project, need to have an idea of how a project is progressing and when the project will be completed. For example, if you are investing in creating an e-commerce site, you need to know when the site can be launched. It is not enough to just say that “the project will be done when it is done” because the stakeholders almost certainly have a limited budget to devote to the project. The people investing in the project cannot determine the business value of the project unless they can have an estimate of how long it will take to complete the project. Developers hate to give estimates. The reason that developers hate to give estimates is that the estimates are almost always completely made up. For example, you really don’t know how long it takes to build a shopping cart until you finish building a shopping cart, and at that point, the estimate is no longer useful. The problem is that writing code is much more like Finding a Cure for Cancer than Building a Brick Wall. Building a brick wall is very straightforward. After you learn how to add one brick to a wall, you understand everything that is involved in adding a brick to a wall. There is no additional research required and no surprises. If, on the other hand, I assembled a team of scientists and asked them to find a cure for cancer, and estimate exactly how long it will take, they would have no idea. The problem is that there are too many unknowns. I don’t know how to cure cancer, I need to do a lot of research here, so I cannot even begin to estimate how long it will take. So developers hate to provide estimates, but the Product Owner and other product stakeholders, have a legitimate need for estimates. Scrum resolves this conflict by using the idea of Story Points. Different teams use different units to represent Story Points. For example, some teams use shirt sizes such as Small, Medium, Large, and X-Large. Some teams prefer to use Coffee Cup sizes such as Tall, Short, and Grande. Finally, some teams like to use numbers from the Fibonacci series. These alternative units are converted into a Story Point value. Regardless of the type of unit which you use to represent Story Points, the goal is the same. Instead of attempting to estimate a Story in hours (which is doomed to failure), you use a much less fine-grained measure of work. A developer team is much more likely to be able to estimate that a Story is Small or X-Large than the exact number of hours required to complete the story. So you can think of Story Points as a compromise between the needs of the Product Owner and the developer team. When a Sprint starts, the developer team devotes more time to thinking about the Stories in a Sprint and the developer team breaks the Stories into Tasks. In Scrum, you estimate the work required to complete a Story by using Story Points and you estimate the work required to complete a task by using hours. The difference between Stories and Tasks is that you don’t create a task until you are just about ready to start working on a task. A task is something that you should be able to create within a day, so you have a much better chance of providing an accurate estimate of the work required to complete a task than a story. Burndown Charts In Scrum, you use Burndown charts to represent the remaining work on a project. You use Release Burndown charts to represent the overall remaining work for a project and you use Sprint Burndown charts to represent the overall remaining work for a particular Sprint. You create a Release Burndown chart by calculating the remaining number of uncompleted Story Points for the entire Product Backlog every day. The vertical axis represents Story Points and the horizontal axis represents time. A Sprint Burndown chart is similar to a Release Burndown chart, but it focuses on the remaining work for a particular Sprint. There are two different types of Sprint Burndown charts. You can either represent the remaining work in a Sprint with Story Points or with task hours (the following image, taken from Wikipedia, uses hours). When each Product Backlog Story is completed, the Release Burndown chart slopes down. When each Story or task is completed, the Sprint Burndown chart slopes down. Burndown charts typically do not always slope down over time. As new work is added to the Product Backlog, the Release Burndown chart slopes up. If new tasks are discovered during a Sprint, the Sprint Burndown chart will also slope up. The purpose of a Burndown chart is to give you a way to track team progress over time. If, halfway through a Sprint, the Sprint Burndown chart is still climbing a hill then you know that you are in trouble. Team Velocity Stakeholders in a project always want more work done faster. For example, the Product Owner for the e-commerce site wants the website to launch before tomorrow. Developers tend to be overly optimistic. Rarely do developers acknowledge the physical limitations of reality. So Project stakeholders and the developer team often collude to delude themselves about how much work can be done and how quickly. Too many software projects begin in a state of optimism and end in frustration as deadlines zoom by. In Scrum, this problem is overcome by calculating a number called the Team Velocity. The Team Velocity is a measure of the average number of Story Points which a team has completed in previous Sprints. Knowing the Team Velocity is important during the Sprint Planning meeting when the Product Owner and the developer team work together to determine the number of stories which can be completed in the next Sprint. If you know the Team Velocity then you can avoid committing to do more work than the team has been able to accomplish in the past, and your team is much more likely to complete all of the work required for the next Sprint. Scrum Master There are three roles in Scrum: the Product Owner, the developer team, and the Scrum Master. I’v e already discussed the Product Owner. The Product Owner is the one and only person who maintains the Product Backlog and prioritizes the stories. I’ve also described the role of the developer team. The members of the developer team do the work of implementing the stories by breaking the stories into tasks. The final role, which I have not discussed, is the role of the Scrum Master. The Scrum Master is responsible for ensuring that the team is following the Scrum process. For example, the Scrum Master is responsible for making sure that there is a Daily Scrum meeting and that everyone answers the standard three questions. The Scrum Master is also responsible for removing (non-technical) impediments which the team might encounter. For example, if the team cannot start work until everyone installs the latest version of Microsoft Visual Studio then the Scrum Master has the responsibility of working with management to get the latest version of Visual Studio as quickly as possible. The Scrum Master can be a member of the developer team. Furthermore, different people can take on the role of the Scrum Master over time. The Scrum Master, however, cannot be the same person as the Product Owner. Using SonicAgile SonicAgile (SonicAgile.com) is an online tool which you can use to manage your projects using Scrum. You can use the SonicAgile Product Backlog to create a prioritized list of stories. You can estimate the size of the Stories using different Story Point units such as Shirt Sizes and Coffee Cup sizes. You can use SonicAgile during the Sprint Planning meeting to select the Stories that you want to complete during a particular Sprint. You can configure Sprints to be any length of time. SonicAgile calculates Team Velocity automatically and displays a warning when you add too many stories to a Sprint. In other words, it warns you when it thinks you are overcommitting in a Sprint. SonicAgile also includes a Scrumboard which displays the list of Stories selected for a Sprint and the tasks associated with each story. You can drag tasks from one task state to another. Finally, SonicAgile enables you to generate Release Burndown and Sprint Burndown charts. You can use these charts to view the progress of your team. To learn more about SonicAgile, visit SonicAgile.com. Summary In this post, I described many of the basic concepts of Scrum. You learned how a Product Owner uses a Product Backlog to create a prioritized list of tasks. I explained why work is completed in Sprints so the developer team can be more productive. I also explained how a developer team uses the daily scrum to coordinate their work. You learned how the developer team uses a Scrumboard to see, at a glance, who is working on what and the state of each task. I also discussed Burndown charts. You learned how you can use both Release and Sprint Burndown charts to track team progress in completing a project. Finally, I described the crucial role of the Scrum Master – the person who is responsible for ensuring that the rules of Scrum are being followed. My goal was not to describe all of the concepts of Scrum. This post was intended to be an introductory overview. For a comprehensive explanation of Scrum, I recommend reading Ken Schwaber’s book Agile Project Management with Scrum: http://www.amazon.com/Agile-Project-Management-Microsoft-Professional/dp/073561993X/ref=la_B001H6ODMC_1_1?ie=UTF8&qid=1345224000&sr=1-1

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  • Round Table - Minimum Cost Algorithm

    - by 7Aces
    Problem Link - http://www.iarcs.org.in/zco2013/index.php/problems/ROUNDTABLE It's dinner time in Castle Camelot, and the fearsome Knights of the Round Table are clamouring for dessert. You, the chef, are in a soup. There are N knights, including King Arthur, each with a different preference for dessert, but you cannot afford to make desserts for all of them. You are given the cost of manufacturing each Knight's preferred dessert-since it is a round table, the list starts with the cost of King Arthur's dessert, and goes counter-clockwise. You decide to pick the cheapest desserts to make, such that for every pair of adjacent Knights, at least one gets his dessert. This will ensure that the Knights do not protest. What is the minimum cost of tonight's dinner, given this condition? I used the Dynamic Programming approach, considering the smallest of i-1 & i-2, & came up with the following code - #include<cstdio> #include<algorithm> using namespace std; int main() { int n,i,j,c,f; scanf("%d",&n); int k[n],m[n][2]; for(i=0;i<n;++i) scanf("%d",&k[i]); m[0][0]=k[0]; m[0][1]=0; m[1][0]=k[1]; m[1][1]=1; for(i=2;i<n;++i) { c=1000; for(j=i-2;j<i;++j) { if(m[j][0]<c) { c=m[j][0]; f=m[j][1];} } m[i][0]=c+k[i]; m[i][1]=f; } if(m[n-2][0]<m[n-1][0] && m[n-2][1]==0) printf("%d\n",m[n-2][0]); else printf("%d\n",m[n-1][0]); } I used the second dimension of the m array to store from which knight the given sequence started (1st or 2nd). I had to do this because of the case when m[n-2]<m[n-1] but the sequence started from knight 2, since that would create two adjacent knights without dessert. The problem arises because of the table's round shape. Now an anomaly arises when I consider the case - 2 1 1 2 1 2. The program gives an answer 5 when the answer should be 4, by picking the 1st, 3rd & 5th knight. At this point, I started to doubt my initial algorithm (approach) itself! Where did I go wrong?

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  • Are you cashing in on the MVP complimentary subscriptions ?

    - by Tarun Arora
    The two most asked questions in the Microsoft technology communities around the Microsoft MVP program are, 1. How do I become a Microsoft MVP? 2. What benefits do I get as an MVP? The answer to the first question has been well answered here. In this blog post, I’ll try and answer the second question.           Please find a comprehensive list of Not for Resale personal subscriptions of various products that Microsoft MVP’s are eligible for Product Description Details JetBrains Resharper, dotTrace, dotCover & WebStorm  https://www.jetbrains.com/resharper/buy/mvp.html RedGate Sql server development, database administration, .net development, azure development (merged with Cerebrata), mySQL development, Oracle development http://www.red-gate.com/community/mvp-program Pluralsight Pluralsight on demand training http://blog.pluralsight.com/2011/02/28/pluralsight-for-mvp/ Cerebrata Cloud storage studio and Azure Diagnostic Manager (part of redgate now) https://www.cerebrata.com/Offers/mvp.aspx Telerik Telerik Ultimate collection & Telerik TeamPulse http://blogs.telerik.com/blogs/posts/11-03-01/telerik-gift-for-microsoft-mvps.aspx Developer Express DevEx controls http://www.devexpress.com/Home/Community/mvp.xml InnerWorking 600 hours of .net training catalogue http://www.innerworkings.com/mvp Typemock Typemock Isolator, Typemock Isolator for Sharepoint developers, Typemock Isolator for web developers, TestDriven.NET http://www.typemock.com/mvp SpeakFlow A suite of tools for creating, managing, and delivering non-linear presentations http://www.speakflow.com/ TechSmith Camtasia Studio, SnagIt, screen cast http://www.techsmith.com/camtasia.html Altova Altova XML spy http://www.altova.com/xml-editor/ Visual SVN VisualSVN Subversion integration plug-in for Visual Studio http://www.visualsvn.com/visualsvn/purchase/mvp/ PreEmptive Solution Professional PreEmptive Analytics, Dotfuscator http://www.preemptive.com/landing/mvp Armadillo Armadillo Adaptive Bug Prevention http://www.armadilloverdrive.com/ IS Decisions NFR license to Userlock, RemoteExec, FileAudit & WinReporter http://www.isdecisions.com/download/mvp-mct-program.htm Idera SQL tools http://www.idera.com/Content/Home.aspx West Wind Help Builder Help builder solution http://www.west-wind.com/weblog/posts/2005/Mar/09/Are-you-a-Microsoft-MVP-Get-a-FREE-copy-of-West-Wind-Html-Help-Builder Bamboo Sharepoint tools http://community.bamboosolutions.com/blogs/partner-advantage-program/archive/2008/08/01/partner-advantage-program-mvp.aspx Nitriq Nitriq code analysis http://blog.nitriq.com/FreeLicensesForMicrosoftMVPs.aspx ByteScout Components, Libraries and Developer Tools http://bytescout.com/buy/purchase_nfr_for_mvp.html YourKit Java and .net Profiler http://yourkit.com/.net/profiler/index.jsp Aspose .NET components http://www.aspose.com/corporate/community/2012_05_08_nfr-licenses-for-community-leaders.aspx Apart from google bing fu; stackoverflow and breathtech were a great help in compiling the above list. If you know of any other benefits, offers or complimentary subscriptions on offer for MVPs not cover in the list above, please add to the comment thread and I’ll have it updated in the list. Enjoy

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  • Dynamic Paging and Sorting

    - by Ricardo Peres
    Since .NET 3.5 brought us LINQ and expressions, I became a great fan of these technologies. There are times, however, when strong typing cannot be used - for example, when you are developing an ObjectDataSource and you need to do paging having just a column name, a page index and a page size, so I set out to fix this. Yes, I know about Dynamic LINQ, and even talked on it previously, but there's no need to add this extra assembly. So, without further delay, here's the code, in both generic and non-generic versions: public static IList ApplyPagingAndSorting(IEnumerable enumerable, Type elementType, Int32 pageSize, Int32 pageIndex, params String [] orderByColumns) { MethodInfo asQueryableMethod = typeof(Queryable).GetMethods(BindingFlags.Static | BindingFlags.Public).Where(m = (m.Name == "AsQueryable") && (m.ContainsGenericParameters == false)).Single(); IQueryable query = (enumerable is IQueryable) ? (enumerable as IQueryable) : asQueryableMethod.Invoke(null, new Object [] { enumerable }) as IQueryable; if ((orderByColumns != null) && (orderByColumns.Length 0)) { PropertyInfo orderByProperty = elementType.GetProperty(orderByColumns [ 0 ]); MemberExpression member = Expression.MakeMemberAccess(Expression.Parameter(elementType, "n"), orderByProperty); LambdaExpression orderBy = Expression.Lambda(member, member.Expression as ParameterExpression); MethodInfo orderByMethod = typeof(Queryable).GetMethods(BindingFlags.Public | BindingFlags.Static).Where(m = m.Name == "OrderBy").ToArray() [ 0 ].MakeGenericMethod(elementType, orderByProperty.PropertyType); query = orderByMethod.Invoke(null, new Object [] { query, orderBy }) as IQueryable; if (orderByColumns.Length 1) { MethodInfo thenByMethod = typeof(Queryable).GetMethods(BindingFlags.Public | BindingFlags.Static).Where(m = m.Name == "ThenBy").ToArray() [ 0 ].MakeGenericMethod(elementType, orderByProperty.PropertyType); PropertyInfo thenByProperty = null; MemberExpression thenByMember = null; LambdaExpression thenBy = null; for (Int32 i = 1; i 0) { MethodInfo takeMethod = typeof(Queryable).GetMethod("Take", BindingFlags.Public | BindingFlags.Static).MakeGenericMethod(elementType); MethodInfo skipMethod = typeof(Queryable).GetMethod("Skip", BindingFlags.Public | BindingFlags.Static).MakeGenericMethod(elementType); query = skipMethod.Invoke(null, new Object [] { query, pageSize * pageIndex }) as IQueryable; query = takeMethod.Invoke(null, new Object [] { query, pageSize }) as IQueryable; } MethodInfo toListMethod = typeof(Enumerable).GetMethod("ToList", BindingFlags.Static | BindingFlags.Public).MakeGenericMethod(elementType); IList list = toListMethod.Invoke(null, new Object [] { query }) as IList; return (list); } public static List ApplyPagingAndSorting(IEnumerable enumerable, Int32 pageSize, Int32 pageIndex, params String [] orderByColumns) { return (ApplyPagingAndSorting(enumerable, typeof(T), pageSize, pageIndex, orderByColumns) as List); } List list = new List { new DateTime(2010, 1, 1), new DateTime(1999, 1, 12), new DateTime(1900, 10, 10), new DateTime(1900, 2, 20), new DateTime(2012, 5, 5), new DateTime(2012, 1, 20) }; List sortedList = ApplyPagingAndSorting(list, 3, 0, "Year", "Month", "Day"); SyntaxHighlighter.config.clipboardSwf = 'http://alexgorbatchev.com/pub/sh/2.0.320/scripts/clipboard.swf'; SyntaxHighlighter.brushes.CSharp.aliases = ['c#', 'c-sharp', 'csharp']; SyntaxHighlighter.all();

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  • Silverlight Cream for March 22, 2010 -- #817

    - by Dave Campbell
    In this Issue: Bart Czernicki, Tim Greenfield, Andrea Boschin(-2-), AfricanGeek, Fredrik Normén, Ian Griffiths, Christian Schormann, Pete Brown, Jeff Handley, Brad Abrams, and Tim Heuer. Shoutout: At the beginning of MIX10, Brad Abrams reported Silverlight 4 and RIA Services Release Candidate Available NOW From SilverlightCream.com: Using the Bing Maps Silverlight control on the Windows Phone 7 Bart Czernicki has a very cool BingMaps and WP7 tutorial up... you're going to want to bookmark this one for sure! Code included and external links... thanks Bart! Silverlight Rx DataClient within MVVM Tim Greenfield has a great post up about Rx and MVVM with Silverlight 3. Lots of good insight into Rx and interesting code bits. SilverVNC - a VNC Viewer with Silverlight 4.0 RC Andrea Boschin digs into Silverlight 4 RC and it's full-trust on sockets and builds an implementation of RFB protocol... give it a try and give Andrea some feedback. Chromeless Window for OOB applications in Silverlight 4.0 RC Andrea Boschin also has a post up on investigating the OOB no-chrome features in SL4RC. Windows Phone 7 and WCF AfricanGeek has his latest video tutorial up and it's on WCF and WP7... I've got a feeling we're all going to have to get our arms around this. Some steps for moving WCF RIA Services Preveiw to the RC version Fredrik Normén details his steps in transitioning to the RC version of RIA Services. Silverlight Business Apps: Module 8.5 - The Value of MEF with Silverlight Ian Griffiths has a video tutorial up at Channel 9 on MEF and Silverlight, posted by John Papa Introducing Blend 4 – For Silverlight, WPF and Windows Phone Christian Schormann has an early MIX10 post up about te new features in Expression Blend with regard to Silverlight, WPF, and WP7. Building your first Silverlight for Windows Phone Application Pete Brown has his first post up on building a WP7 app with the MIX10 bits. Lookups in DataGrid and DataForm with RIA Services Jeff Handley elaborates on a post by someone else about using lookup data in the DataGrid and DataForm with RIA Services Silverlight 4 + RIA Services - Ready for Business: Starting a New Project with the Business Application Template Brad Abrams is starting a series highlighting the key features of Silverlight 4 and RIA with the new releases. He has a post up Silverlight 4 + RIA Services - Ready for Business: Index, including links and source. Then in this first post of the series, he introduces the Business Application Template. Custom Window Chrome and Events Watch a tutorial video by Tim Heuer on creating custom chrome for OOB apps. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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  • Lost all privileges since upgrading to 13.10

    - by Chris Poole
    Since upgrading to 13.10, I no longer have the 'privileges' to do the following things: Mount USB/CDROM drives Run software centre or software updater Press the GUI shut down or restart buttons Unlock my account in the 'settings - user accounts' section (padlock is greyed out) Also, when logging on as a guest user I get error messages relating to Compiz crashing with SIGSEGV and it hangs on a blank wallpaper screen. However, I still am able to use sudo in the terminal. Output of 'groups' is jenchris adm dialout cdrom sudo audio video plugdev lpadmin admin pulse pulse-access sambashare sudo usermod -U username doesn't have any effect Output of sudo dpkg-reconfigure -phigh -a acpid stop/waiting acpid start/running, process 30454 * Starting AppArmor profiles Skipping profile in /etc/apparmor.d/disable: usr.bin.firefox Skipping profile in /etc/apparmor.d/disable: usr.sbin.rsyslogd [ OK ] * Reloading AppArmor profiles Skipping profile in /etc/apparmor.d/disable: usr.bin.firefox Skipping profile in /etc/apparmor.d/disable: usr.sbin.rsyslogd [ OK ] apport stop/waiting apport start/running gpg: key 437D05B5: "Ubuntu Archive Automatic Signing Key <[email protected]>" not changed gpg: key FBB75451: "Ubuntu CD Image Automatic Signing Key <[email protected]>" not changed gpg: key C0B21F32: "Ubuntu Archive Automatic Signing Key (2012) <[email protected]>" not changed gpg: key EFE21092: "Ubuntu CD Image Automatic Signing Key (2012) <[email protected]>" not changed gpg: Total number processed: 4 gpg: unchanged: 4 atd stop/waiting atd start/running, process 1388 avahi-daemon stop/waiting avahi-daemon start/running, process 1521 Rebuilding /usr/share/applications/bamf-2.index... update-alternatives: using /usr/share/man/man7/bash-builtins.7.gz to provide /usr/share/man/man7/builtins.7.gz (builtins.7.gz) in auto mode update-binfmts: warning: current package is openjdk-7, but binary format already installed by openjdk-6 binfmt-support stop/waiting bluetooth stop/waiting bluetooth start/running, process 4255 update-initramfs: deferring update (trigger activated) /var/lib/dpkg/info/compiz.config: 1: /var/lib/dpkg/info/compiz.config: [general]: not found /var/lib/dpkg/info/compiz.config: 2: /var/lib/dpkg/info/compiz.config: backend: not found /var/lib/dpkg/info/compiz.config: 3: /var/lib/dpkg/info/compiz.config: plugin_list_autosort: not found /var/lib/dpkg/info/compiz.config: 5: /var/lib/dpkg/info/compiz.config: [gnome_session]: not found /var/lib/dpkg/info/compiz.config: 6: /var/lib/dpkg/info/compiz.config: backend: not found /var/lib/dpkg/info/compiz.config: 7: /var/lib/dpkg/info/compiz.config: integration: not found /var/lib/dpkg/info/compiz.config: 8: /var/lib/dpkg/info/compiz.config: plugin_list_autosort: not found /var/lib/dpkg/info/compiz.config: 9: /var/lib/dpkg/info/compiz.config: profile: not found /var/lib/dpkg/info/compiz.config: 11: /var/lib/dpkg/info/compiz.config: [general_ubuntu]: not found /var/lib/dpkg/info/compiz.config: 12: /var/lib/dpkg/info/compiz.config: backend: not found /var/lib/dpkg/info/compiz.config: 13: /var/lib/dpkg/info/compiz.config: integration: not found /var/lib/dpkg/info/compiz.config: 14: /var/lib/dpkg/info/compiz.config: plugin_list_autosort: not found /var/lib/dpkg/info/compiz.config: 15: /var/lib/dpkg/info/compiz.config: profile: not found

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  • CRMIT Solution´s CRM++ Asterisk Telephony Connector Achieves Oracle Validated Integration with Oracle Sales Cloud

    - by Richard Lefebvre
    To achieve Oracle Validated Integration, Oracle partners are required to meet a stringent set of requirements that are based on the needs and priorities of the customers. Based on a Telephony Application Programming Interface (TAPI) framework the CRM++ Asterisk Telephony Connector integrates the Asterisk telephony solutions with Oracle® Sales Cloud. "The CRM++ Asterisk Telephony Connector for Oracle® Sales Cloud showcases CRMIT Solutions focus and commitment to extend the Customer Experience (CX) expertise to our existing and potential customers," said Vinod Reddy, Founder & CEO, CRMIT Solutions. "Oracle® Validated Integration applies a rigorous technical review and test process," said Kevin O’Brien, senior director, ISV and SaaS Strategy, Oracle®. "Achieving Oracle® Validated Integration through Oracle® PartnerNetwork gives our customers confidence that the CRM++ Asterisk Telephony Connector for Oracle® Sales Cloud has been validated and that the products work together as designed. This helps reduce deployment risk and improves the user experience for our joint customers." CRM++ is a suite of native Customer Experience solutions for Oracle® CRM On Demand, Oracle® Sales Cloud and Oracle® RightNow Cloud Service. With over 3000+ users the CRM++ framework helps extend the Customer Experience (CX) and the power of Customer Relations Management features including Email WorkBench, Self Service Portal, Mobile CRM, Social CRM and Computer Telephony Integration.. About CRMIT Solutions CRMIT Solutions is a pioneer in delivering SaaS-based customer experience (CX) consulting and solutions. With more than 200 certified customer relationship management (CRM) consultants and more than 175 successful CRM deployments globally, CRMIT Solutions offers a range of CRM++ applications for accelerated deployments including various rapid implementation and migration utilities for Oracle® Sales Cloud, Oracle® CRM On Demand, Oracle® Eloqua, Oracle® Social Relationship Management and Oracle® RightNow Cloud Service. About Oracle Validated Integration Oracle Validated Integration, available through the Oracle PartnerNetwork (OPN), gives customers confidence that the integration of complementary partner software products with Oracle Applications and specific Oracle Fusion Middleware solutions have been validated, and the products work together as designed. This can help customers reduce risk, improve system implementation cycles, and provide for smoother upgrades and simpler maintenance. Oracle Validated Integration applies a rigorous technical process to review partner integrations. Partners who have successfully completed the program are authorized to use the “Oracle Validated Integration” logo. For more information, please visit Oracle.com at http://www.oracle.com/us/partnerships/solutions/index.html.

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  • Resources such as libraries, engines and frameworks to make Javacript-based MMORTS? [closed]

    - by hhh
    I am looking for resources outlined to make a MMORTS with Javascript as the client-side, probably just a simple canvas for the frontend. The guy in the video here mentions that JavaScript is one of the most misunderstood language -- and I do believe that. I think one can make quite cool games with it in the future. So I am now proactively looking for resources and perhaps some ideas. My first idea contained Node.js, C and NetBSD/bozohttpd (or the-4-7-chars' *ix-thing with green-logo -thing, move the q here) but I acknowledge my beginner -style approach -- this issue is broad and not only for one person to make it all-the-time-improved project! So I think perfect for community to tinker. Some games and examples possibly easy to make into MMORTS BrowserQuest here under MPL 2.0 and its content licensed under CC-BY-SA 3.0 (source here) [proprietary] LoU here and built with JS/Qooxdoo/c#/Windows-Server/ISS/etc, source. MY ANSWER BEGINS HERE TO BE MOVED BELOW, REQUIRING RE-OPENING. PLEASE, VOTE TO OPEN IT -- HELP US TO TINKER! My answer Generic Is there an MMO-related research body? Although about Android, certain things also appropriate with JS -game: Are there any 2D gaming libraries/frameworks/engines for Android? Why is it so hard to develop a MMO? Browser based MMO Architecture MMO architecture - Highly Scalable with Reporting capabilities What are the Elements of an MMO Game? Is this the right architecture for our MMORPG mobile game? Looking for architectures to develop massive multiplayer game server Information on seamless MMO server architecture Game-mechanics (search) Question sounding like about LoU: What are the different ways to balance an online multiplayer game where user spend different amounts of time online? Building an instance system What are the different ways to balance an online multiplayer game where user spend different amounts of time online? Hosting is it possible to make a MMO starting with scalable hosting? Should I keep login server apart from game server? MMO techniques, algorithms and resources for keeping bandwidth low? MMO Proxy Server Javascript and Client-based things What do I need to do a MMORTS in JavaScript with small amount of Developers? How to update the monsters in my MMO server using Node.js and Socket.IO Are there any good html 5 mmo design tutorials? Networking Loadbalancing Questions Something about TCP, routers, NAT, etc: How do I start writing an MMO game server? Who does the AI calculations in an MMO? They need someone more knowledgable to work with, a lot of cases where the same words mean different things. Data Structures What data structure should I use for a Diablo/WoW-style talent tree? Game Engine Need an engine for MMO mockup Helper sites http://www.gamedev.net/page/index.html

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  • Web.Config is Cached

    - by SGWellens
    There was a question from a student over on the Asp.Net forums about improving site performance. The concern was that every time an app setting was read from the Web.Config file, the disk would be accessed. With many app settings and many users, it was believed performance would suffer. Their intent was to create a class to hold all the settings, instantiate it and fill it from the Web.Config file on startup. Then, all the settings would be in RAM. I knew this was not correct and didn't want to just say so without any corroboration, so I did some searching. Surprisingly, this is a common misconception. I found other code postings that cached the app settings from Web.Config. Many people even thanked the posters for the code. In a later post, the student said their text book recommended caching the Web.Config file. OK, here's the deal. The Web.Config file is already cached. You do not need to re-cache it. From this article http://msdn.microsoft.com/en-us/library/aa478432.aspx It is important to realize that the entire <appSettings> section is read, parsed, and cached the first time we retrieve a setting value. From that point forward, all requests for setting values come from an in-memory cache, so access is quite fast and doesn't incur any subsequent overhead for accessing the file or parsing the XML. The reason the misconception is prevalent may be because it's hard to search for Web.Config and cache without getting a lot of hits on how to setup caching in the Web.Config file. So here's a string for search engines to index on: "Is the Web.Config file Cached?" A follow up question was, are the connection strings cached? Yes. http://msdn.microsoft.com/en-us/library/ms178683.aspx At run time, ASP.NET uses the Web.Config files to hierarchically compute a unique collection of configuration settings for each incoming URL request. These settings are calculated only once and then cached on the server. And, as everyone should know, if you modify the Web.Config file, the web application will restart. I hope this helps people to NOT write code! Steve WellensCodeProject

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  • Web.Config is Cached

    - by SGWellens
    There was a question from a student over on the Asp.Net forums about improving site performance. The concern was that every time an app setting was read from the Web.Config file, the disk would be accessed. With many app settings and many users, it was believed performance would suffer. Their intent was to create a class to hold all the settings, instantiate it and fill it from the Web.Config file on startup. Then, all the settings would be in RAM. I knew this was not correct and didn't want to just say so without any corroboration, so I did some searching. Surprisingly, this is a common misconception. I found other code postings that cached the app settings from Web.Config. Many people even thanked the posters for the code. In a later post, the student said their text book recommended caching the Web.Config file. OK, here's the deal. The Web.Config file is already cached. You do not need to re-cache it. From this article http://msdn.microsoft.com/en-us/library/aa478432.aspx It is important to realize that the entire <appSettings> section is read, parsed, and cached the first time we retrieve a setting value. From that point forward, all requests for setting values come from an in-memory cache, so access is quite fast and doesn't incur any subsequent overhead for accessing the file or parsing the XML. The reason the misconception is prevalent may be because it's hard to search for Web.Config and cache without getting a lot of hits on how to setup caching in the Web.Config file. So here's a string for search engines to index on: "Is the Web.Config file Cached?" A follow up question was, are the connection strings cached? Yes. http://msdn.microsoft.com/en-us/library/ms178683.aspx At run time, ASP.NET uses the Web.Config files to hierarchically compute a unique collection of configuration settings for each incoming URL request. These settings are calculated only once and then cached on the server. And, as everyone should know, if you modify the Web.Config file, the web application will restart. I hope this helps people to NOT write code!   Steve WellensCodeProject

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  • Qml and QfileSystemModel interaction problem

    - by user136432
    I'm having some problem in realizing an interaction between QML and C++ to obtain a very basic file browser that is shown within a ListView. I tried to use as model for my data the QT class QFileSystemModel, but it did't work as I expected, probably I didn't fully understand the QT class documentation about the use of this model or the example I found on the internet. Here is the code that I am using: File main.cpp #include <QModelIndex> #include <QFileSystemModel> #include <QQmlContext> #include <QApplication> #include "qtquick2applicationviewer.h" int main(int argc, char *argv[]) { QApplication app(argc, argv); QFileSystemModel* model = new QFileSystemModel; model->setRootPath("C:/"); model->setFilter(QDir::Files | QDir::AllDirs); QtQuick2ApplicationViewer viewer; // Make QFileSystemModel* available for QML use. viewer.rootContext()->setContextProperty("myFileModel", model); viewer.setMainQmlFile(QStringLiteral("qml/ProvaQML/main.qml")); viewer.showExpanded(); return app.exec(); } File main.qml Rectangle { id: main width: 800 height: 600 ListView { id: view property string root_path: "C:/Users" x: 40 y: 20 width: parent.width - (2*x) height: parent.height - (2*y) VisualDataModel { id: myVisualModel model: myFileModel // Get the model QFileSystemModel exposed from C++ delegate { Rectangle { width: 210; height: 20; radius: 5; border.width: 2; border.color: "orange"; color: "yellow"; Text { text: fileName; x: parent.x + 10; } MouseArea { anchors.fill: parent onDoubleClicked: { myVisualModel.rootIndex = myVisualModel.modelIndex(index) } } } } } highlight: Rectangle { color: "lightsteelblue"; radius: 5 } focus: true } } The first problem with this code is that first elements that I can see within my list are my PC logical drives even if I set a specific path. Then when I first double click on drive "C:\" it shows the list of files and directories on that path, but when I double click on a directory a second time the screen flickers for one moment and then it shows again the PC logical drives. Can anyone tell me how should I use the QFileSystemModel class with a ListView QML object? Thanks in advance! Carlo

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  • Querying Networking Statistics: dlstat(1M)

    - by user12612042
    Oracle Solaris 11 took another big leap forward in networking technologies providing a reliable, secure and scalable infrastructure to meet the growing needs of today's datacenter implementations. Oracle Solaris 11 introduced a new and powerful network stack architecture, also known as Project Crossbow. From Solaris 11 onwards, we introduced a command line tool viz. dlstat(1M) to query network statistics. dlstat (for datalink statistics) is a statistics querying counterpart for dladm(1M) - the datalink administration tool. The tool is very easy to get started. Just type dlstat on a shell prompt on Solaris 11 (or later). For example,: # dlstat LINK IPKTS RBYTES OPKTS OBYTES net0 834.11K 145.91M 575.19K 104.24M net1 7.87K 2.04M 0 0 In this example, the system has two datalinks net0 and net1. The output columns denote input packets/bytes as well as output packets/bytes. The numbers are abbreviated in xxx.xxUnit format. However, one could get the actual counts by simply running dlstat -u R (R for raw): # dlstat -u R LINK IPKTS RBYTES OPKTS OBYTES net0 834271 145931244 575246 104242934 net1 7869 2036958 0 0 In addition, dlstat also supports various subcommands dlstat help The following subcommands are supported: Stats : show-aggr show-ether show-link show-phys show-bridge For more info, run: dlstat help {default|} I will only describe couple of interesting subcommands/options here. For a comprehensive description of all the dlstat subcommands refer dlstat's official manual . For NICs that support multiple rings (e.g. ixgbe), dlstat show-phys -r allows us to query per Rx ring statistics. For example: dlstat show-phys -r net4 LINK TYPE INDEX IPKTS RBYTES net4 rx 0 0 0 net4 rx 1 0 0 net4 rx 2 0 0 net4 rx 3 0 0 net4 rx 4 0 0 net4 rx 5 0 0 net4 rx 6 0 0 net4 rx 7 0 0 In this case, net4 is just a vanity name for an ixgbe datalink. This view is especially useful if one wants to look at the network traffic spread across all the available rings. Furthermore, any of the dlstat commands could be run with -i option to periodically query and display stats. For example, running dlstat show-phys -r net4 -i 5 will emit per Rx ring stats every 5 seconds. This is especially useful while analyzing a live system. Similarly, dlstat show-phys -t could be used to query per Tx ring stats. -r and -t could also be combined as dlstat show-phys -rt to query both Rx as well as Tx stats at the same time. Finally, there is also a quick way to dump ALL the stats. Just run dlstat -A. You probably want to redirect this output to a file because you are going to get a whole load of stats :-).

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  • How to perform feature upgrade in SharePoint2010 part2

    - by ybbest
    In my last post, I showed you how to perform feature upgrade and upgrade my feature from 0.0.0.0 to 1.0.0.1. In this post, I’d like to continue on this topic and upgrade the feature again. For the first version of my solution, I deploy a document library with a custom document set content type and then upgrade the solution so I index the application number column. Now , I will create a new version of the solution so that it will remove the threshold of the list. You can download the solution here. Once you extract your solution, the first version is in the original folder. In order to deploy the original solution, you need to run the sitecreation.ps1 in the script folder. The version 1.1 will be in the Upgrade folder and version 1.2 will be in the Upgrade2 folder. You need to make the following changes to the existing solution. 1. Modify the ApplicationLibrary.Template.xml as highlighted below: 2. Adding the following code into the feature event receiver. </pre> public override void FeatureUpgrading(SPFeatureReceiverProperties properties, string upgradeActionName, System.Collections.Generic.IDictionary<string, string> parameters) { base.FeatureUpgrading(properties, upgradeActionName, parameters); SPWeb web = GetFeatureWeb(properties); SPList applicationLibrary = web.Lists.TryGetList(ApplicationLibraryNamesConstant.ApplicationLibraryName); switch (upgradeActionName) { case "IndexApplicationNumber": if (applicationLibrary != null) { SPField queueField = applicationLibrary.Fields["ApplicationNumber"]; queueField.Indexed = true; queueField.Update(); } break; case "RemoveListThreshold": applicationLibrary.EnableThrottling = false; applicationLibrary.Update(); break; } } <pre> 3. Package your solution and run the feature upgrade PowerShell script. $wspFolder ="v1.2" $scriptPath=Split-Path $myInvocation.MyCommand.Path $siteUrl = "http://ybbest" $featureToCheckGuid="1b9d84cd-227d-45f1-92d4-a43008aa8fe7" $requiredFeatureVersion="1.0.0.1" $siteUrlOfFeatureToBeChecked="http://ybbest" AppendLog "Starting Solution UpgradeSolutionAndFeatures.ps1" Magenta & "$scriptPath\UpgradeSolutionAndFeatures.ps1" $siteUrl $wspFolder $featureToCheckGuid $requiredFeatureVersion $siteUrlOfFeatureToBeChecked Write-Host AppendLog "All features updated" "Green" References: Feature upgrade.

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  • ASP.NET Frameworks and Raw Throughput Performance

    - by Rick Strahl
    A few days ago I had a curious thought: With all these different technologies that the ASP.NET stack has to offer, what's the most efficient technology overall to return data for a server request? When I started this it was mere curiosity rather than a real practical need or result. Different tools are used for different problems and so performance differences are to be expected. But still I was curious to see how the various technologies performed relative to each just for raw throughput of the request getting to the endpoint and back out to the client with as little processing in the actual endpoint logic as possible (aka Hello World!). I want to clarify that this is merely an informal test for my own curiosity and I'm sharing the results and process here because I thought it was interesting. It's been a long while since I've done any sort of perf testing on ASP.NET, mainly because I've not had extremely heavy load requirements and because overall ASP.NET performs very well even for fairly high loads so that often it's not that critical to test load performance. This post is not meant to make a point  or even come to a conclusion which tech is better, but just to act as a reference to help understand some of the differences in perf and give a starting point to play around with this yourself. I've included the code for this simple project, so you can play with it and maybe add a few additional tests for different things if you like. Source Code on GitHub I looked at this data for these technologies: ASP.NET Web API ASP.NET MVC WebForms ASP.NET WebPages ASMX AJAX Services  (couldn't get AJAX/JSON to run on IIS8 ) WCF Rest Raw ASP.NET HttpHandlers It's quite a mixed bag, of course and the technologies target different types of development. What started out as mere curiosity turned into a bit of a head scratcher as the results were sometimes surprising. What I describe here is more to satisfy my curiosity more than anything and I thought it interesting enough to discuss on the blog :-) First test: Raw Throughput The first thing I did is test raw throughput for the various technologies. This is the least practical test of course since you're unlikely to ever create the equivalent of a 'Hello World' request in a real life application. The idea here is to measure how much time a 'NOP' request takes to return data to the client. So for this request I create the simplest Hello World request that I could come up for each tech. Http Handler The first is the lowest level approach which is an HTTP handler. public class Handler : IHttpHandler { public void ProcessRequest(HttpContext context) { context.Response.ContentType = "text/plain"; context.Response.Write("Hello World. Time is: " + DateTime.Now.ToString()); } public bool IsReusable { get { return true; } } } WebForms Next I added a couple of ASPX pages - one using CodeBehind and one using only a markup page. The CodeBehind page simple does this in CodeBehind without any markup in the ASPX page: public partial class HelloWorld_CodeBehind : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Response.Write("Hello World. Time is: " + DateTime.Now.ToString() ); Response.End(); } } while the Markup page only contains some static output via an expression:<%@ Page Language="C#" AutoEventWireup="false" CodeBehind="HelloWorld_Markup.aspx.cs" Inherits="AspNetFrameworksPerformance.HelloWorld_Markup" %> Hello World. Time is <%= DateTime.Now %> ASP.NET WebPages WebPages is the freestanding Razor implementation of ASP.NET. Here's the simple HelloWorld.cshtml page:Hello World @DateTime.Now WCF REST WCF REST was the token REST implementation for ASP.NET before WebAPI and the inbetween step from ASP.NET AJAX. I'd like to forget that this technology was ever considered for production use, but I'll include it here. Here's an OperationContract class: [ServiceContract(Namespace = "")] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class WcfService { [OperationContract] [WebGet] public Stream HelloWorld() { var data = Encoding.Unicode.GetBytes("Hello World" + DateTime.Now.ToString()); var ms = new MemoryStream(data); // Add your operation implementation here return ms; } } WCF REST can return arbitrary results by returning a Stream object and a content type. The code above turns the string result into a stream and returns that back to the client. ASP.NET AJAX (ASMX Services) I also wanted to test ASP.NET AJAX services because prior to WebAPI this is probably still the most widely used AJAX technology for the ASP.NET stack today. Unfortunately I was completely unable to get this running on my Windows 8 machine. Visual Studio 2012  removed adding of ASP.NET AJAX services, and when I tried to manually add the service and configure the script handler references it simply did not work - I always got a SOAP response for GET and POST operations. No matter what I tried I always ended up getting XML results even when explicitly adding the ScriptHandler. So, I didn't test this (but the code is there - you might be able to test this on a Windows 7 box). ASP.NET MVC Next up is probably the most popular ASP.NET technology at the moment: MVC. Here's the small controller: public class MvcPerformanceController : Controller { public ActionResult Index() { return View(); } public ActionResult HelloWorldCode() { return new ContentResult() { Content = "Hello World. Time is: " + DateTime.Now.ToString() }; } } ASP.NET WebAPI Next up is WebAPI which looks kind of similar to MVC. Except here I have to use a StringContent result to return the response: public class WebApiPerformanceController : ApiController { [HttpGet] public HttpResponseMessage HelloWorldCode() { return new HttpResponseMessage() { Content = new StringContent("Hello World. Time is: " + DateTime.Now.ToString(), Encoding.UTF8, "text/plain") }; } } Testing Take a minute to think about each of the technologies… and take a guess which you think is most efficient in raw throughput. The fastest should be pretty obvious, but the others - maybe not so much. The testing I did is pretty informal since it was mainly to satisfy my curiosity - here's how I did this: I used Apache Bench (ab.exe) from a full Apache HTTP installation to run and log the test results of hitting the server. ab.exe is a small executable that lets you hit a URL repeatedly and provides counter information about the number of requests, requests per second etc. ab.exe and the batch file are located in the \LoadTests folder of the project. An ab.exe command line  looks like this: ab.exe -n100000 -c20 http://localhost/aspnetperf/api/HelloWorld which hits the specified URL 100,000 times with a load factor of 20 concurrent requests. This results in output like this:   It's a great way to get a quick and dirty performance summary. Run it a few times to make sure there's not a large amount of varience. You might also want to do an IISRESET to clear the Web Server. Just make sure you do a short test run to warm up the server first - otherwise your first run is likely to be skewed downwards. ab.exe also allows you to specify headers and provide POST data and many other things if you want to get a little more fancy. Here all tests are GET requests to keep it simple. I ran each test: 100,000 iterations Load factor of 20 concurrent connections IISReset before starting A short warm up run for API and MVC to make sure startup cost is mitigated Here is the batch file I used for the test: IISRESET REM make sure you add REM C:\Program Files (x86)\Apache Software Foundation\Apache2.2\bin REM to your path so ab.exe can be found REM Warm up ab.exe -n100 -c20 http://localhost/aspnetperf/MvcPerformance/HelloWorldJsonab.exe -n100 -c20 http://localhost/aspnetperf/api/HelloWorldJson ab.exe -n100 -c20 http://localhost/AspNetPerf/WcfService.svc/HelloWorld ab.exe -n100000 -c20 http://localhost/aspnetperf/handler.ashx > handler.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/HelloWorld_CodeBehind.aspx > AspxCodeBehind.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/HelloWorld_Markup.aspx > AspxMarkup.txt ab.exe -n100000 -c20 http://localhost/AspNetPerf/WcfService.svc/HelloWorld > Wcf.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/MvcPerformance/HelloWorldCode > Mvc.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/api/HelloWorld > WebApi.txt I ran each of these tests 3 times and took the average score for Requests/second, with the machine otherwise idle. I did see a bit of variance when running many tests but the values used here are the medians. Part of this has to do with the fact I ran the tests on my local machine - result would probably more consistent running the load test on a separate machine hitting across the network. I ran these tests locally on my laptop which is a Dell XPS with quad core Sandibridge I7-2720QM @ 2.20ghz and a fast SSD drive on Windows 8. CPU load during tests ran to about 70% max across all 4 cores (IOW, it wasn't overloading the machine). Ideally you can try running these tests on a separate machine hitting the local machine. If I remember correctly IIS 7 and 8 on client OSs don't throttle so the performance here should be Results Ok, let's cut straight to the chase. Below are the results from the tests… It's not surprising that the handler was fastest. But it was a bit surprising to me that the next fastest was WebForms and especially Web Forms with markup over a CodeBehind page. WebPages also fared fairly well. MVC and WebAPI are a little slower and the slowest by far is WCF REST (which again I find surprising). As mentioned at the start the raw throughput tests are not overly practical as they don't test scripting performance for the HTML generation engines or serialization performances of the data engines. All it really does is give you an idea of the raw throughput for the technology from time of request to reaching the endpoint and returning minimal text data back to the client which indicates full round trip performance. But it's still interesting to see that Web Forms performs better in throughput than either MVC, WebAPI or WebPages. It'd be interesting to try this with a few pages that actually have some parsing logic on it, but that's beyond the scope of this throughput test. But what's also amazing about this test is the sheer amount of traffic that a laptop computer is handling. Even the slowest tech managed 5700 requests a second, which is one hell of a lot of requests if you extrapolate that out over a 24 hour period. Remember these are not static pages, but dynamic requests that are being served. Another test - JSON Data Service Results The second test I used a JSON result from several of the technologies. I didn't bother running WebForms and WebPages through this test since that doesn't make a ton of sense to return data from the them (OTOH, returning text from the APIs didn't make a ton of sense either :-) In these tests I have a small Person class that gets serialized and then returned to the client. The Person class looks like this: public class Person { public Person() { Id = 10; Name = "Rick"; Entered = DateTime.Now; } public int Id { get; set; } public string Name { get; set; } public DateTime Entered { get; set; } } Here are the updated handler classes that use Person: Handler public class Handler : IHttpHandler { public void ProcessRequest(HttpContext context) { var action = context.Request.QueryString["action"]; if (action == "json") JsonRequest(context); else TextRequest(context); } public void TextRequest(HttpContext context) { context.Response.ContentType = "text/plain"; context.Response.Write("Hello World. Time is: " + DateTime.Now.ToString()); } public void JsonRequest(HttpContext context) { var json = JsonConvert.SerializeObject(new Person(), Formatting.None); context.Response.ContentType = "application/json"; context.Response.Write(json); } public bool IsReusable { get { return true; } } } This code adds a little logic to check for a action query string and route the request to an optional JSON result method. To generate JSON, I'm using the same JSON.NET serializer (JsonConvert.SerializeObject) used in Web API to create the JSON response. WCF REST   [ServiceContract(Namespace = "")] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class WcfService { [OperationContract] [WebGet] public Stream HelloWorld() { var data = Encoding.Unicode.GetBytes("Hello World " + DateTime.Now.ToString()); var ms = new MemoryStream(data); // Add your operation implementation here return ms; } [OperationContract] [WebGet(ResponseFormat=WebMessageFormat.Json,BodyStyle=WebMessageBodyStyle.WrappedRequest)] public Person HelloWorldJson() { // Add your operation implementation here return new Person(); } } For WCF REST all I have to do is add a method with the Person result type.   ASP.NET MVC public class MvcPerformanceController : Controller { // // GET: /MvcPerformance/ public ActionResult Index() { return View(); } public ActionResult HelloWorldCode() { return new ContentResult() { Content = "Hello World. Time is: " + DateTime.Now.ToString() }; } public JsonResult HelloWorldJson() { return Json(new Person(), JsonRequestBehavior.AllowGet); } } For MVC all I have to do for a JSON response is return a JSON result. ASP.NET internally uses JavaScriptSerializer. ASP.NET WebAPI public class WebApiPerformanceController : ApiController { [HttpGet] public HttpResponseMessage HelloWorldCode() { return new HttpResponseMessage() { Content = new StringContent("Hello World. Time is: " + DateTime.Now.ToString(), Encoding.UTF8, "text/plain") }; } [HttpGet] public Person HelloWorldJson() { return new Person(); } [HttpGet] public HttpResponseMessage HelloWorldJson2() { var response = new HttpResponseMessage(HttpStatusCode.OK); response.Content = new ObjectContent<Person>(new Person(), GlobalConfiguration.Configuration.Formatters.JsonFormatter); return response; } } Testing and Results To run these data requests I used the following ab.exe commands:REM JSON RESPONSES ab.exe -n100000 -c20 http://localhost/aspnetperf/Handler.ashx?action=json > HandlerJson.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/MvcPerformance/HelloWorldJson > MvcJson.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/api/HelloWorldJson > WebApiJson.txt ab.exe -n100000 -c20 http://localhost/AspNetPerf/WcfService.svc/HelloWorldJson > WcfJson.txt The results from this test run are a bit interesting in that the WebAPI test improved performance significantly over returning plain string content. Here are the results:   The performance for each technology drops a little bit except for WebAPI which is up quite a bit! From this test it appears that WebAPI is actually significantly better performing returning a JSON response, rather than a plain string response. Snag with Apache Benchmark and 'Length Failures' I ran into a little snag with Apache Benchmark, which was reporting failures for my Web API requests when serializing. As the graph shows performance improved significantly from with JSON results from 5580 to 6530 or so which is a 15% improvement (while all others slowed down by 3-8%). However, I was skeptical at first because the WebAPI test reports showed a bunch of errors on about 10% of the requests. Check out this report: Notice the Failed Request count. What the hey? Is WebAPI failing on roughly 10% of requests when sending JSON? Turns out: No it's not! But it took some sleuthing to figure out why it reports these failures. At first I thought that Web API was failing, and so to make sure I re-ran the test with Fiddler attached and runiisning the ab.exe test by using the -X switch: ab.exe -n100 -c10 -X localhost:8888 http://localhost/aspnetperf/api/HelloWorldJson which showed that indeed all requests where returning proper HTTP 200 results with full content. However ab.exe was reporting the errors. After some closer inspection it turned out that the dates varying in size altered the response length in dynamic output. For example: these two results: {"Id":10,"Name":"Rick","Entered":"2012-09-04T10:57:24.841926-10:00"} {"Id":10,"Name":"Rick","Entered":"2012-09-04T10:57:24.8519262-10:00"} are different in length for the number which results in 68 and 69 bytes respectively. The same URL produces different result lengths which is what ab.exe reports. I didn't notice at first bit the same is happening when running the ASHX handler with JSON.NET result since it uses the same serializer that varies the milliseconds. Moral: You can typically ignore Length failures in Apache Benchmark and when in doubt check the actual output with Fiddler. Note that the other failure values are accurate though. Another interesting Side Note: Perf drops over Time As I was running these tests repeatedly I was finding that performance steadily dropped from a startup peak to a 10-15% lower stable level. IOW, with Web API I'd start out with around 6500 req/sec and in subsequent runs it keeps dropping until it would stabalize somewhere around 5900 req/sec occasionally jumping lower. For these tests this is why I did the IIS RESET and warm up for individual tests. This is a little puzzling. Looking at Process Monitor while the test are running memory very quickly levels out as do handles and threads, on the first test run. Subsequent runs everything stays stable, but the performance starts going downwards. This applies to all the technologies - Handlers, Web Forms, MVC, Web API - curious to see if others test this and see similar results. Doing an IISRESET then resets everything and performance starts off at peak again… Summary As I stated at the outset, these were informal to satiate my curiosity not to prove that any technology is better or even faster than another. While there clearly are differences in performance the differences (other than WCF REST which was by far the slowest and the raw handler which was by far the highest) are relatively minor, so there is no need to feel that any one technology is a runaway standout in raw performance. Choosing a technology is about more than pure performance but also about the adequateness for the job and the easy of implementation. The strengths of each technology will make for any minor performance difference we see in these tests. However, to me it's important to get an occasional reality check and compare where new technologies are heading. Often times old stuff that's been optimized and designed for a time of less horse power can utterly blow the doors off newer tech and simple checks like this let you compare. Luckily we're seeing that much of the new stuff performs well even in V1.0 which is great. To me it was very interesting to see Web API perform relatively badly with plain string content, which originally led me to think that Web API might not be properly optimized just yet. For those that caught my Tweets late last week regarding WebAPI's slow responses was with String content which is in fact considerably slower. Luckily where it counts with serialized JSON and XML WebAPI actually performs better. But I do wonder what would make generic string content slower than serialized code? This stresses another point: Don't take a single test as the final gospel and don't extrapolate out from a single set of tests. Certainly Twitter can make you feel like a fool when you post something immediate that hasn't been fleshed out a little more <blush>. Egg on my face. As a result I ended up screwing around with this for a few hours today to compare different scenarios. Well worth the time… I hope you found this useful, if not for the results, maybe for the process of quickly testing a few requests for performance and charting out a comparison. Now onwards with more serious stuff… Resources Source Code on GitHub Apache HTTP Server Project (ab.exe is part of the binary distribution)© Rick Strahl, West Wind Technologies, 2005-2012Posted in ASP.NET  Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • JRockit R28/JRockit Mission Control 4.0 is out!

    - by Marcus Hirt
    The next major release of JRockit is finally out! Here are some highlights: Includes the all new JRockit Flight Recorder – supersedes the old JRockit Runtime Analyser. The new flight recorder is inspired by the “black box” in airplanes. It uses a highly efficient recording engine and thread local buffers to capture data about the runtime and the application running in the JVM. It can be configured to always be on, so that whenever anything “interesting” happens, data can be dumped for some time back. Think of it as your own personal profiling time machine. Automatic shortest path calculation in Memleak – no longer any need for running around in circles when trying to find your way back to a thread root from an instance. Memleak can now show class loader related information and split graphs on a per class loader basis. More easily configured JMX agent – default port for both RMI Registry and RMI Server can be configured, and is by default the same, allowing easier configuration of firewalls. Up to 64 GB (was 4GB) compressed references. Per thread allocation profiling in the Management Console. Native Memory Tracking – it is now possible to track native memory allocations with very high resolution. The information can either be accessed using JRCMD, or the dedicated Native Memory Tracking experimental plug-in for the Management Console (alas only available for the upcoming 4.0.1 release). JRockit can now produce heap dumps in HPROF format. Cooperative suspension – JRockit is no longer using system signals for stopping threads, which could lead to hangs if signals were lost or blocked (for example bad NFS shares). Now threads check periodically to see if they are suspended. VPAT/Section 508 compliant JRMC – greatly improved keyboard navigation and screen reader support. See New and Noteworthy for more information. JRockit Mission Control 4.0.0 can be downloaded from here: http://www.oracle.com/technology/software/products/jrockit/index.html <shameless ad> There is even a book to go with JRMC 4.0.0/JRockit R28! http://www.packtpub.com/oracle-jrockit-the-definitive-guide/book/ </shameless ad>

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  • Skinny controller in ASP.NET MVC 4

    - by thangchung
    Rails community are always inspire a lot of best ideas. I really love this community by the time. One of these is "Fat models and skinny controllers". I have spent a lot of time on ASP.NET MVC, and really I did some miss-takes, because I made the controller so fat. That make controller is really dirty and very hard to maintain in the future. It is violate seriously SRP principle and KISS as well. But how can we achieve that in ASP.NET MVC? That question is really clear after I read "Manning ASP.NET MVC 4 in Action". It is simple that we can separate it into ActionResult, and try to implementing logic and persistence data inside this. In last 2 years, I have read this from Jimmy Bogard blog, but in that time I never had a consideration about it. That's enough for talking now. I just published a sample on ASP.NET MVC 4, implemented on Visual Studio 2012 RC at here. I used EF framework at here for implementing persistence layer, and also use 2 free templates from internet to make the UI for this sample. In this sample, I try to implementing the simple magazine website that managing all articles, categories and news. It is not finished at all in this time, but no problems, because I just show you about how can we make the controller skinny. And I wanna hear more about your ideas. The first thing, I am abstract the base ActionResult class like this:    public abstract class MyActionResult : ActionResult, IEnsureNotNull     {         public abstract void EnsureAllInjectInstanceNotNull();     }     public abstract class ActionResultBase<TController> : MyActionResult where TController : Controller     {         protected readonly Expression<Func<TController, ActionResult>> ViewNameExpression;         protected readonly IExConfigurationManager ConfigurationManager;         protected ActionResultBase (Expression<Func<TController, ActionResult>> expr)             : this(DependencyResolver.Current.GetService<IExConfigurationManager>(), expr)         {         }         protected ActionResultBase(             IExConfigurationManager configurationManager,             Expression<Func<TController, ActionResult>> expr)         {             Guard.ArgumentNotNull(expr, "ViewNameExpression");             Guard.ArgumentNotNull(configurationManager, "ConfigurationManager");             ViewNameExpression = expr;             ConfigurationManager = configurationManager;         }         protected ViewResult GetViewResult<TViewModel>(TViewModel viewModel)         {             var m = (MethodCallExpression)ViewNameExpression.Body;             if (m.Method.ReturnType != typeof(ActionResult))             {                 throw new ArgumentException("ControllerAction method '" + m.Method.Name + "' does not return type ActionResult");             }             var result = new ViewResult             {                 ViewName = m.Method.Name             };             result.ViewData.Model = viewModel;             return result;         }         public override void ExecuteResult(ControllerContext context)         {             EnsureAllInjectInstanceNotNull();         }     } I also have an interface for validation all inject objects. This interface make sure all inject objects that I inject using Autofac container are not null. The implementation of this as below public interface IEnsureNotNull     {         void EnsureAllInjectInstanceNotNull();     } Afterwards, I am just simple implementing the HomePageViewModelActionResult class like this public class HomePageViewModelActionResult<TController> : ActionResultBase<TController> where TController : Controller     {         #region variables & ctors         private readonly ICategoryRepository _categoryRepository;         private readonly IItemRepository _itemRepository;         private readonly int _numOfPage;         public HomePageViewModelActionResult(Expression<Func<TController, ActionResult>> viewNameExpression)             : this(viewNameExpression,                    DependencyResolver.Current.GetService<ICategoryRepository>(),                    DependencyResolver.Current.GetService<IItemRepository>())         {         }         public HomePageViewModelActionResult(             Expression<Func<TController, ActionResult>> viewNameExpression,             ICategoryRepository categoryRepository,             IItemRepository itemRepository)             : base(viewNameExpression)         {             _categoryRepository = categoryRepository;             _itemRepository = itemRepository;             _numOfPage = ConfigurationManager.GetAppConfigBy("NumOfPage").ToInteger();         }         #endregion         #region implementation         public override void ExecuteResult(ControllerContext context)         {             base.ExecuteResult(context);             var cats = _categoryRepository.GetCategories();             var mainViewModel = new HomePageViewModel();             var headerViewModel = new HeaderViewModel();             var footerViewModel = new FooterViewModel();             var mainPageViewModel = new MainPageViewModel();             headerViewModel.SiteTitle = "Magazine Website";             if (cats != null && cats.Any())             {                 headerViewModel.Categories = cats.ToList();                 footerViewModel.Categories = cats.ToList();             }             mainPageViewModel.LeftColumn = BindingDataForMainPageLeftColumnViewModel();             mainPageViewModel.RightColumn = BindingDataForMainPageRightColumnViewModel();             mainViewModel.Header = headerViewModel;             mainViewModel.DashBoard = new DashboardViewModel();             mainViewModel.Footer = footerViewModel;             mainViewModel.MainPage = mainPageViewModel;             GetViewResult(mainViewModel).ExecuteResult(context);         }         public override void EnsureAllInjectInstanceNotNull()         {             Guard.ArgumentNotNull(_categoryRepository, "CategoryRepository");             Guard.ArgumentNotNull(_itemRepository, "ItemRepository");             Guard.ArgumentMustMoreThanZero(_numOfPage, "NumOfPage");         }         #endregion         #region private functions         private MainPageRightColumnViewModel BindingDataForMainPageRightColumnViewModel()         {             var mainPageRightCol = new MainPageRightColumnViewModel();             mainPageRightCol.LatestNews = _itemRepository.GetNewestItem(_numOfPage).ToList();             mainPageRightCol.MostViews = _itemRepository.GetMostViews(_numOfPage).ToList();             return mainPageRightCol;         }         private MainPageLeftColumnViewModel BindingDataForMainPageLeftColumnViewModel()         {             var mainPageLeftCol = new MainPageLeftColumnViewModel();             var items = _itemRepository.GetNewestItem(_numOfPage);             if (items != null && items.Any())             {                 var firstItem = items.First();                 if (firstItem == null)                     throw new NoNullAllowedException("First Item".ToNotNullErrorMessage());                 if (firstItem.ItemContent == null)                     throw new NoNullAllowedException("First ItemContent".ToNotNullErrorMessage());                 mainPageLeftCol.FirstItem = firstItem;                 if (items.Count() > 1)                 {                     mainPageLeftCol.RemainItems = items.Where(x => x.ItemContent != null && x.Id != mainPageLeftCol.FirstItem.Id).ToList();                 }             }             return mainPageLeftCol;         }         #endregion     }  Final step, I get into HomeController and add some line of codes like this [Authorize]     public class HomeController : BaseController     {         [AllowAnonymous]         public ActionResult Index()         {             return new HomePageViewModelActionResult<HomeController>(x=>x.Index());         }         [AllowAnonymous]         public ActionResult Details(int id)         {             return new DetailsViewModelActionResult<HomeController>(x => x.Details(id), id);         }         [AllowAnonymous]         public ActionResult Category(int id)         {             return new CategoryViewModelActionResult<HomeController>(x => x.Category(id), id);         }     } As you see, the code in controller is really skinny, and all the logic I move to the custom ActionResult class. Some people said, it just move the code out of controller and put it to another class, so it is still hard to maintain. Look like it just move the complicate codes from one place to another place. But if you have a look and think it in details, you have to find out if you have code for processing all logic that related to HttpContext or something like this. You can do it on Controller, and try to delegating another logic  (such as processing business requirement, persistence data,...) to custom ActionResult class. Tell me more your thinking, I am really willing to hear all of its from you guys. All source codes can be find out at here. Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="http://weblogs.asp.net//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs");

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  • Oracle Financial Analytics for SAP Certified with Oracle Data Integrator EE

    - by denis.gray
    Two days ago Oracle announced the release of Oracle Financial Analytics for SAP.  With the amount of press this has garnered in the past two days, there's a key detail that can't be missed.  This release is certified with Oracle Data Integrator EE - now making the combination of Data Integration and Business Intelligence a force to contend with.  Within the Oracle Press Release there were two important bullets: ·         Oracle Financial Analytics for SAP includes a pre-packaged ABAP code compliant adapter and is certified with Oracle Data Integrator Enterprise Edition to integrate SAP Financial Accounting data directly with the analytic application.  ·         Helping to integrate SAP financial data and disparate third-party data sources is Oracle Data Integrator Enterprise Edition which delivers fast, efficient loading and transformation of timely data into a data warehouse environment through its high-performance Extract Load and Transform (E-LT) technology. This is very exciting news, demonstrating Oracle's overall commitment to Oracle Data Integrator EE.   This is a great way to start off the new year and we look forward to building on this momentum throughout 2011.   The following links contain additional information and media responses about the Oracle Financial Analytics for SAP release. IDG News Service (Also appeared in PC World, Computer World, CIO: "Oracle is moving further into rival SAP's turf with Oracle Financial Analytics for SAP, a new BI (business intelligence) application that can crunch ERP (enterprise resource planning) system financial data for insights." Information Week: "Oracle talks a good game about the appeal of an optimized, all-Oracle stack. But the company also recognizes that we live in a predominantly heterogeneous IT world" CRN: "While some businesses with SAP Financial Accounting already use Oracle BI, those integrations had to be custom developed. The new offering provides pre-built integration capabilities." ECRM Guide:  "Among other features, Oracle Financial Analytics for SAP helps front-line managers improve financial performance and decision-making with what the company says is comprehensive, timely and role-based information on their departments' expenses and revenue contributions."   SAP Getting Started Guide for ODI on OTN: http://www.oracle.com/technetwork/middleware/data-integrator/learnmore/index.html For more information on the ODI and its SAP connectivity please review the Oracle® Fusion Middleware Application Adapters Guide for Oracle Data Integrator11g Release 1 (11.1.1)

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  • How to perform feature upgrade in SharePoint2010 part1

    - by ybbest
    Once your custom SharePoint solution went into production. Any changes made to it require you to perform feature upgrade. Today, I’d like to show you how to perform feature upgrade. For the first version of my solution, I deploy a document library with a custom document set content type. You can download the solution here. Once you extract your solution, the first version is in the original folder. In order to deploy the original solution, you need to run the sitecreation.ps1 in the script folder. Next, I will modify the solution so that I will index the application number in the document library I just created in my original solution. 1. Modify the ApplicationLibrary.Template.xml as highlighted below: 2. Adding the following code into the feature event receiver. public override void FeatureUpgrading(SPFeatureReceiverProperties properties, string upgradeActionName, System.Collections.Generic.IDictionary<string, string> parameters) { base.FeatureUpgrading(properties, upgradeActionName, parameters); SPWeb web = GetFeatureWeb(properties); switch (upgradeActionName) { case "IndexApplicationNumber": SPList applicationLibrary = web.Lists.TryGetList(ApplicationLibraryNamesConstant.ApplicationLibraryName); if (applicationLibrary != null) { SPField queueField = applicationLibrary.Fields["ApplicationNumber"]; queueField.Indexed = true; queueField.Update(); } break; } } 3. Package your solution and run the feature upgrade PowerShell script. $wspFolder ="v1.1" $scriptPath=Split-Path $myInvocation.MyCommand.Path $siteUrl = "http://ybbest" $featureToCheckGuid="1b9d84cd-227d-45f1-92d4-a43008aa8fe7" $requiredFeatureVersion="0.0.0.0" $siteUrlOfFeatureToBeChecked="http://ybbest" AppendLog "Starting Solution UpgradeSolutionAndFeatures.ps1" Magenta & "$scriptPath\UpgradeSolutionAndFeatures.ps1" $siteUrl $wspFolder $featureToCheckGuid $requiredFeatureVersion $siteUrlOfFeatureToBeChecked Write-Host AppendLog "All features updated" "Green" Note: If you have not version your feature explicitly , your feature version will be 0.0.0.0 . References: Feature upgrade.

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  • Chunking a List - .NET vs Python

    - by Abhijeet Patel
    Chunking a List As I mentioned last time, I'm knee deep in python these days. I come from a statically typed background so it's definitely a mental adjustment. List comprehensions is BIG in Python and having worked with a few of them I can see why. Let's say we need to chunk a list into sublists of a specified size. Here is how we'd do it in C#  static class Extensions   {       public static IEnumerable<List<T>> Chunk<T>(this List<T> l, int chunkSize)       {           if (chunkSize <0)           {               throw new ArgumentException("chunkSize cannot be negative", "chunkSize");           }           for (int i = 0; i < l.Count; i += chunkSize)           {               yield return new List<T>(l.Skip(i).Take(chunkSize));           }       }    }    static void Main(string[] args)  {           var l = new List<string> { "a", "b", "c", "d", "e", "f","g" };             foreach (var list in l.Chunk(7))           {               string str = list.Aggregate((s1, s2) => s1 + "," + s2);               Console.WriteLine(str);           }   }   A little wordy but still pretty concise thanks to LINQ.We skip the iteration number plus chunkSize elements and yield out a new List of chunkSize elements on each iteration. The python implementation is a bit more terse. def chunkIterable(iter, chunkSize):      '''Chunks an iterable         object into a list of the specified chunkSize     '''        assert hasattr(iter, "__iter__"), "iter is not an iterable"      for i in xrange(0, len(iter), chunkSize):          yield iter[i:i + chunkSize]    if __name__ == '__main__':      l = ['a', 'b', 'c', 'd', 'e', 'f']      generator = chunkIterable(l,2)      try:          while(1):              print generator.next()      except StopIteration:          pass   xrange generates elements in the specified range taking in a seed and returning a generator. which can be used in a for loop(much like using a C# iterator in a foreach loop) Since chunkIterable has a yield statement, it turns this method into a generator as well. iter[i:i + chunkSize] essentially slices the list based on the current iteration index and chunksize and creates a new list that we yield out to the caller one at a time. A generator much like an iterator is a state machine and each subsequent call to it remembers the state at which the last call left off and resumes execution from that point. The caveat to keep in mind is that since variables are not explicitly typed we need to ensure that the object passed in is iterable using hasattr(iter, "__iter__").This way we can perform chunking on any object which is an "iterable", very similar to accepting an IEnumerable in the .NET land

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  • Getting Started With Sinatra

    - by Liam McLennan
    Sinatra is a Ruby DSL for building web applications. It is distinguished from its peers by its minimalism. Here is hello world in Sinatra: require 'rubygems' require 'sinatra' get '/hi' do "Hello World!" end A haml view is rendered by: def '/' haml :name_of_your_view end Haml is also new to me. It is a ruby-based view engine that uses significant white space to avoid having to close tags. A hello world web page in haml might look like: %html %head %title Hello World %body %div Hello World You see how the structure is communicated using indentation instead of opening and closing tags. It makes views more concise and easier to read. Based on my syntax highlighter for Gherkin I have started to build a sinatra web application that publishes syntax highlighted gherkin feature files. I have found that there is a need to have features online so that customers can access them, and so that they can be linked to project management tools like Jira, Mingle, trac etc. The first thing I want my application to be able to do is display a list of the features that it knows about. This will happen when a user requests the root of the application. Here is my sinatra handler: get '/' do feature_service = Finding::FeatureService.new(Finding::FeatureFileFinder.new, Finding::FeatureReader.new) @features = feature_service.features(settings.feature_path, settings.feature_extensions) haml :index end The handler and the view are in the same scope so the @features variable will be available in the view. This is the same way that rails passes data between actions and views. The view to render the result is: %h2 Features %ul - @features.each do |feature| %li %a{:href => "/feature/#{feature.name}"}= feature.name Clearly this is not a complete web page. I am using a layout to provide the basic html page structure. This view renders an <li> for each feature, with a link to /feature/#{feature.name}. Here is what the page looks like: When the user clicks on one of the links I want to display the contents of that feature file. The required handler is: get '/feature/:feature' do @feature_name = params[:feature] feature_service = Finding::FeatureService.new(Finding::FeatureFileFinder.new, Finding::FeatureReader.new) # TODO replace with feature_service.feature(name) @feature = feature_service.features(settings.feature_path, settings.feature_extensions).find do |feature| feature.name == @feature_name end haml :feature end and the view: %h2= @feature.name %pre{:class => "brush: gherkin"}= @feature.description %div= partial :_back_to_index %script{:type => "text/javascript", :src => "/scripts/shCore.js"} %script{:type => "text/javascript", :src => "/scripts/shBrushGherkin.js"} %script{:type => "text/javascript" } SyntaxHighlighter.all(); Now when I click on the Search link I get a nicely formatted feature file: If you would like see the full source it is available on bitbucket.

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  • Quickie Guide Getting Java Embedded Running on Raspberry Pi

    - by hinkmond
    Gary C. and I did a Bay Area Java User Group presentation of how to get Java Embedded running on a RPi. See: here. But, if you want the Quickie Guide on how to get Java up and running on the RPi, then follow these steps (which I'm doing right now as we speak, since I got my RPi in the mail on Monday. Woo-hoo!!!). So, follow along at home as I do the same steps here on my board... 1. Download the Win32DiskImager if you are on Windows, or use dd on a Linux PC: https://launchpad.net/win32-image-writer/0.6/0.6/+download/win32diskimager-binary.zip 2. Download the RPi Debian Wheezy image from here: http://files.velocix.com/c1410/images/debian/7/2012-08-08-wheezy-armel/2012-08-08-wheezy-armel.zip 3. Insert a blank 4GB SD Card into your Windows or Linux PC. 4. Use either Win32DiskImager or Linux dd to burn the unzipped image from #2 to the SD Card. 5. Insert the SD Card into your RPi. Connect an Ethernet cable to your RPi to your network. Connect the RPi Power Adapter. 6. The RPi will boot onto your network. Find its IP address using Windows Wireshark or Linux: sudo tcpdump -vv -ieth0 port 67 and port 68 7. ssh to your RPi: ssh <ip_addr_rpi> -l pi <Password: "raspberry"> 8. Download Java SE Embedded: http://www.oracle.com/technetwork/java/embedded/downloads/javase/index.html NOTE: First click accept, then choose the first bundle in the list: ARMv6/7 Linux - Headless EABI, VFP, SoftFP ABI, Little Endian - ejre-7u6-fcs-b24-linux-arm-vfp-client_headless-10_aug_2012.tar.gz 9. scp the bundle from #8 to your RPi: scp <ejre-bundle> pi@<ip_addr_rpi> 10. mkdir /usr/local, untar the bundle from #9 and rename (move) the ejre1.7.0_06 directory to /usr/local/java That's it! You are ready to roll with Java Embedded on your RPi. Hinkmond

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  • Oracle Coherence 3.5 : Create Internet-scale applications using Oracle's high-performance data grid

    - by frederic.michiara
    Oracle Coherence Coherence provides replicated and distributed (partitioned) data management and caching services on top of a reliable, highly scalable peer-to-peer clustering protocol. Coherence has no single points of failure; it automatically and transparently fails over and redistributes its clustered data management services when a server becomes inoperative or is disconnected from the network. When a new server is added, or when a failed server is restarted, it automatically joins the cluster and Coherence fails back services to it, transparently redistributing the cluster load. Coherence includes network-level fault tolerance features and transparent soft re-start capability to enable servers to self-heal. For the ones looking at an easy reading and first good approach to Oracle Coherence, I would recommend reading the following book : Overview of Oracle Coherence 3.5 Build scalable web sites and Enterprise applications using a market-leading data grid product Design and implement your domain objects to work most effectively with Coherence and apply Domain Driven Designs (DDD) to Coherence applications Leverage Coherence events and continuous queries to provide real-time updates to client applications Successfully integrate various persistence technologies, such as JDBC, Hibernate, or TopLink, with Coherence Filled with numerous examples that provide best practice guidance, and a number of classes you can readily reuse within your own applications This book is targeted to Architects and developers, and as in our team we're more about Solutions Architects than developers I found interest in this book as it help to understand better Oracle Coherence and its value. The only point I may not agree with the authors is that Oracle Coherence is not an alternative to Oracle RAC in providing High Availability, but combining both Oracle RAC and Oracle Coherence will help Architects and Customers to reach higher level of service and high-availability. This book is available on https://www.packtpub.com/oracle-coherence-3-5/book Need to find out about Table of contents : https://www.packtpub.com/toc/oracle-coherence-35-table-contents Discover a sample chapter : https://www.packtpub.com/sites/default/files/6125_Oracle%20Coherence_SampleChapter.pdf Read also articles from the Authors on http://www.packtpub.com/ : Working with Aggregators in Oracle Coherence 3.5 Working with Value Extractors and Simplifying Queries in Oracle Coherence 3.5 Querying the Data Grid in Coherence 3.5: Obtaining Query Results and Using Indexes Installing Coherence 3.5 and Accessing the Data Grid: Part 1 Installing Coherence 3.5 and Accessing the Data Grid: Part 2 For more information on Oracle Coherence : What Oracle Coherence Can Do for You... : http://www.oracle.com/technology/products/coherence/coherencedatagrid/coherence_solutions.html Oracle Coherence on OTN : http://www.oracle.com/technology/products/coherence/index.html Oracle Coherence Knowledge Base : http://coherence.oracle.com/display/COH/Oracle+Coherence+Knowledge+Base+Home

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  • .NET development on a “Retina” MacBook Pro

    - by Jeff
    The rumor that Apple would release a super high resolution version of its 15” laptop has been around for quite awhile, and one I watched closely. After more than three years with a 17” MacBook Pro, and all of the screen real estate it offered, I was ready to replace it with something much lighter. It was a fantastic machine, still doing 6 or 7 hours after 460 charge cycles, but I wanted lighter and faster. With the SSD I put in it, I was able to sell it for $750. The appeal of higher resolution goes way back, when I would plug into a projector and scale up. Consolas, as it turns out, is a nice looking font for code when it’s bigger. While I have mostly indifference for iOS, I have to admit that a higher dot pitch on the iPhone and iPad is pretty to look at. So I ordered the new 15” “Retina” model as soon as the Apple Store went live with it, and got it seven days later. I’ve been primarily using Parallels as my VM of choice from OS X for about five years. They recently put out an update for compatibility with the display, though I’m not entirely sure what that means. I figured there would have to be some messing around to get the VM to look right. The combination that seems to work best is this: Set the display in OS X to “more room,” which is roughly the equivalent of the 1920x1200 that my 17” did. It’s not as stunning as the text at the default 1440x900 equivalent (in OS X), but it’s still quite readable. Parallels still doesn’t entirely know what to do with the high resolution, though what it should do is somehow treat it as native. That flaw aside, I set the Windows 7 scaling to 125%, and it generally looks pretty good. It’s not really taking advantage of the display for sharpness, but hopefully that’s something that Parallels will figure out. Screen tweaking aside, I got the base model with 16 gigs of RAM, so I give the VM 8. I can boot a Windows 7 VM in 9 seconds. Nine seconds! The Windows Experience Index scores are all 7 and above, except for graphics, which are both at 6. Again, that’s in a VM. It’s hard to believe there’s something so fast in a little slim package like that. Hopefully this one gets me at least three years, like the last one.

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