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• BizTalk: History of one project architecture

  - by Leonid Ganeline

  "In the beginning God made heaven and earth. Then he started to integrate." At the very start was the requirement: integrate two working systems. Small digging up: It was one system. It was good but IT guys want to change it to the new one, much better, chipper, more flexible, and more progressive in technologies, more suitable for the future, for the faster world and hungry competitors. One thing. One small, little thing. We cannot turn off the old system (call it A, because it was the first), turn on the new one (call it B, because it is second but not the last one). The A has a hundreds users all across a country, they must study B. A still has a lot nice custom features, home-made features that cannot disappear. These features have to be moved to the B and it is a long process, months and months of redevelopment. So, the decision was simple. Let’s move not jump, let’s both systems working side-by-side several months. In this time we could teach the users and move all custom A’s special functionality to B. That automatically means both systems should work side-by-side all these months and use the same data. Data in A and B must be in sync. That’s how the integration projects get birth. Moreover, the specific of the user tasks requires the both systems must be in sync in real-time. Nightly synchronization is not working, absolutely.   First draft The first draft seems simple. Both systems keep data in SQL databases. When data changes, the Create, Update, Delete operations performed on the data, and the sync process could be started. The obvious decision is to use triggers on tables. When we are talking about data, we are talking about several entities. For example, Orders and Items [in Orders]. We decided to use the BizTalk Server to synchronize systems. Why it was chosen is another story. Second draft   Let’s take an example how it works in more details. 1.       User creates a new entity in the A system. This fires an insert trigger on the entity table. Trigger has to pass the message “Entity created”. This message includes all attributes of the new entity, but I focused on the Id of this entity in the A system. Notation for this message is id.A. System A sends id.A to the BizTalk Server. 2.       BizTalk transforms id.A to the format of the system B. This is easiest part and I will not focus on this kind of transformations in the following text. The message on the picture is still id.A but it is in slightly different format, that’s why it is changing in color. BizTalk sends id.A to the system B. 3.       The system B creates the entity on its side. But it uses different id-s for entities, these id-s are id.B. System B saves id.A+id.B. System B sends the message id.A+id.B back to the BizTalk. 4.       BizTalk sends the message id.A+id.B to the system A. 5.       System A saves id.A+id.B. Why both id-s should be saved on both systems? It was one of the next requirements. Users of both systems have to know the systems are in sync or not in sync. Users working with the entity on the system A can see the id.B and use it to switch to the system B and work there with the copy of the same entity. The decision was to store the pairs of entity id-s on both sides. If there is only one id, the entities are not in sync yet (for the Create operation). Third draft Next problem was the reliability of the synchronization. The synchronizing process can be interrupted on each step, when message goes through the wires. It can be communication problem, timeout, temporary shutdown one of the systems, the second system cannot be synchronized by some internal reason. There were several potential problems that prevented from enclosing the whole synchronization process in one transaction. Decision was to restart the whole sync process if it was not finished (in case of the error). For this purpose was created an additional service. Let’s call it the Resync service. We still keep the id pairs in both systems, but only for the fast access not for the synchronization process. For the synchronizing these id-s now are kept in one main place, in the Resync service database. The Resync service keeps record as: ·       Id.A ·       Id.B ·       Entity.Type ·       Operation (Create, Update, Delete) ·       IsSyncStarted (true/false) ·       IsSyncFinished (true/false0 The example now looks like: 1.       System A creates id.A. id.A is saved on the A. Id.A is sent to the BizTalk. 2.       BizTalk sends id.A to the Resync and to the B. id.A is saved on the Resync. 3.       System B creates id.B. id.A+id.B are saved on the B. id.A+id.B are sent to the BizTalk. 4.       BizTalk sends id.A+id.B to the Resync and to the A. id.A+id.B are saved on the Resync. 5.       id.A+id.B are saved on the B. Resync changes the IsSyncStarted and IsSyncFinished flags accordingly. The Resync service implements three main methods: ·       Save (id.A, Entity.Type, Operation) ·       Save (id.A, id.B, Entity.Type, Operation) ·       Resync () Two Save() are used to save id-s to the service storage. See in the above example, in 2 and 4 steps. What about the Resync()? It is the method that finishes the interrupted synchronization processes. If Save() is started by the trigger event, the Resync() is working as an independent process. It periodically scans the Resync storage to find out “unfinished” records. Then it restarts the synchronization processes. It tries to synchronize them several times then gives up.     One more thing, both systems A and B must tolerate duplicates of one synchronizing process. Say on the step 3 the system B was not able to send id.A+id.B back. The Resync service must restart the synchronization process that will send the id.A to B second time. In this case system B must just send back again also created id.A+id.B pair without errors. That means “tolerate duplicates”. Fourth draft Next draft was created only because of the aesthetics. As it always happens, aesthetics gave significant performance gain to the whole system. First was the stupid question. Why do we need this additional service with special database? Can we just master the BizTalk to do something like this Resync() does? So the Resync orchestration is doing the same thing as the Resync service. It is started by the Id.A and finished by the id.A+id.B message. The first works as a Start message, the second works as a Finish message.     Here is a diagram the whole process without errors. It is pretty straightforward. The Resync orchestration is waiting for the Finish message specific period of time then resubmits the Id.A message. It resubmits the Id.A message specific number of times then gives up and gets suspended. It can be resubmitted then it starts the whole process again: waiting [, resubmitting [, get suspended]], finishing. Tuning up The Resync orchestration resubmits the id.A message with special “Resubmitted” flag. The subscription filter on the Resync orchestration includes predicate as (Resubmit_Flag != “Resubmitted”). That means only the first Sync orchestration starts the Resync orchestration. Other Sync orchestration instantiated by the resubmitting can finish this Resync orchestration but cannot start another instance of the Resync   Here is a diagram where system B was inaccessible for some period of time. The Resync orchestration resubmitted the id.A two times. Then system B got the response the id.A+id.B and this finished the Resync service execution. What is interesting about this, there were submitted several identical id.A messages and only one id.A+id.B message. Because of this, the system B and the Resync must tolerate the duplicate messages. We also told about this requirement for the system B. Now the same requirement is for the Resunc. Let’s assume the system B was very slow in the first response and the Resync service had time to resubmit two id.A messages. System B responded not, as it was in previous case, with one id.A+id.B but with two id.A+id.B messages. First of them finished the Resync execution for the id.A. What about the second id.A+id.B? Where it goes? So, we have to add one more internal requirement. The whole solution must tolerate many identical id.A+id.B messages. It is easy task with the BizTalk. I added the “SinkExtraMessages” subscriber (orchestration with one receive shape), that just get these messages and do nothing. Real design Real architecture is much more complex and interesting. In reality each system can submit several id.A almost simultaneously and completely unordered. There are not only the “Create entity” operation but the Update and Delete operations. And these operations relate each other. Say the Update operation after Delete means not the same as Update after Create. In reality there are entities related each other. Say the Order and Order Items. Change on one of it could start the series of the operations on another. Moreover, the system internals are the “black boxes” and we cannot predict the exact content and order of the operation series. It worth to say, I had to spend a time to manage the zombie message problems. The zombies are still here, but this is not a problem now. And this is another story. What is interesting in the last design? One orchestration works to help another to be more reliable. Why two orchestration design is more reliable, isn’t it something strange? The Synch orchestration takes all the message exchange between systems, here is the area where most of the errors could happen. The Resync orchestration sends and receives messages only within the BizTalk server. Is there another design? Sure. All Resync functionality could be implemented inside the Sync orchestration. Hey guys, some other ideas?

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• If You Include the Groovy Editor...

  - by Geertjan

  ...in a NetBeans RCP application, what additional JARs will you need to include for the Groovy Editor to work? Leaving aside the debate on the current state & quality of the NetBeans Groovy Editor, so, assuming you need the Groovy support that the NetBeans Groovy Editor provides, you would check the Groovy Editor checkbox in the Project Properties dialog of your application: As you can see, however, the Groovy Editor depends on other modules, some of which, in turn, depend on yet other modules, and so on. So, I clicked the "Resolve" button above and then created a ZIP distribution, to see which additional JARs had been included. Until that point, I had only been using the "platform" cluster, which means that absolutely everything found in the ZIP's "ide" cluster and "java" cluster have only been included so that the Groovy Editor could be included, i.e., all thanks to clicking the "Resolve" button above. Let's first look at what that means for the "java" cluster: That's not so bad and kind of a side effect of Groovy being Java, i.e., a lot of Java functionality is needed. Now let's look at the "ide" cluster: So, in answer to the original question, if all you want in your NetBeans Platform application, in terms of editor functionality, is the Groovy Editor, then you have a pretty high price to pay. At the very least, I would have assumed that the project support JARs and the debugger support JARs would not be so tightly coupled with the Groovy Editor. That would be a cool thing to separate out from the editor support.

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• C#/.NET Little Wonders: Constraining Generics with Where Clause

  - by James Michael Hare

  Back when I was primarily a C++ developer, I loved C++ templates.  The power of writing very reusable generic classes brought the art of programming to a brand new level.  Unfortunately, when .NET 1.0 came about, they didn’t have a template equivalent.  With .NET 2.0 however, we finally got generics, which once again let us spread our wings and program more generically in the world of .NET However, C# generics behave in some ways very differently from their C++ template cousins.  There is a handy clause, however, that helps you navigate these waters to make your generics more powerful. The Problem – C# Assumes Lowest Common Denominator In C++, you can create a template and do nearly anything syntactically possible on the template parameter, and C++ will not check if the method/fields/operations invoked are valid until you declare a realization of the type.  Let me illustrate with a C++ example: 1: // compiles fine, C++ makes no assumptions as to T 2: template <typename T> 3: class ReverseComparer 4: { 5: public: 6: int Compare(const T& lhs, const T& rhs) 7: { 8: return rhs.CompareTo(lhs); 9: } 10: }; Notice that we are invoking a method CompareTo() off of template type T.  Because we don’t know at this point what type T is, C++ makes no assumptions and there are no errors. C++ tends to take the path of not checking the template type usage until the method is actually invoked with a specific type, which differs from the behavior of C#: 1: // this will NOT compile! C# assumes lowest common denominator. 2: public class ReverseComparer<T> 3: { 4: public int Compare(T lhs, T rhs) 5: { 6: return lhs.CompareTo(rhs); 7: } 8: } So why does C# give us a compiler error even when we don’t yet know what type T is?  This is because C# took a different path in how they made generics.  Unless you specify otherwise, for the purposes of the code inside the generic method, T is basically treated like an object (notice I didn’t say T is an object). That means that any operations, fields, methods, properties, etc that you attempt to use of type T must be available at the lowest common denominator type: object.  Now, while object has the broadest applicability, it also has the fewest specific.  So how do we allow our generic type placeholder to do things more than just what object can do? Solution: Constraint the Type With Where Clause So how do we get around this in C#?  The answer is to constrain the generic type placeholder with the where clause.  Basically, the where clause allows you to specify additional constraints on what the actual type used to fill the generic type placeholder must support. You might think that narrowing the scope of a generic means a weaker generic.  In reality, though it limits the number of types that can be used with the generic, it also gives the generic more power to deal with those types.  In effect these constraints says that if the type meets the given constraint, you can perform the activities that pertain to that constraint with the generic placeholders. Constraining Generic Type to Interface or Superclass One of the handiest where clause constraints is the ability to specify the type generic type must implement a certain interface or be inherited from a certain base class. For example, you can’t call CompareTo() in our first C# generic without constraints, but if we constrain T to IComparable<T>, we can: 1: public class ReverseComparer<T> 2: where T : IComparable<T> 3: { 4: public int Compare(T lhs, T rhs) 5: { 6: return lhs.CompareTo(rhs); 7: } 8: } Now that we’ve constrained T to an implementation of IComparable<T>, this means that our variables of generic type T may now call any members specified in IComparable<T> as well.  This means that the call to CompareTo() is now legal. If you constrain your type, also, you will get compiler warnings if you attempt to use a type that doesn’t meet the constraint.  This is much better than the syntax error you would get within C++ template code itself when you used a type not supported by a C++ template. Constraining Generic Type to Only Reference Types Sometimes, you want to assign an instance of a generic type to null, but you can’t do this without constraints, because you have no guarantee that the type used to realize the generic is not a value type, where null is meaningless. Well, we can fix this by specifying the class constraint in the where clause.  By declaring that a generic type must be a class, we are saying that it is a reference type, and this allows us to assign null to instances of that type: 1: public static class ObjectExtensions 2: { 3: public static TOut Maybe<TIn, TOut>(this TIn value, Func<TIn, TOut> accessor) 4: where TOut : class 5: where TIn : class 6: { 7: return (value != null) ? accessor(value) : null; 8: } 9: } In the example above, we want to be able to access a property off of a reference, and if that reference is null, pass the null on down the line.  To do this, both the input type and the output type must be reference types (yes, nullable value types could also be considered applicable at a logical level, but there’s not a direct constraint for those). Constraining Generic Type to only Value Types Similarly to constraining a generic type to be a reference type, you can also constrain a generic type to be a value type.  To do this you use the struct constraint which specifies that the generic type must be a value type (primitive, struct, enum, etc). Consider the following method, that will convert anything that is IConvertible (int, double, string, etc) to the value type you specify, or null if the instance is null. 1: public static T? ConvertToNullable<T>(IConvertible value) 2: where T : struct 3: { 4: T? result = null; 5:  6: if (value != null) 7: { 8: result = (T)Convert.ChangeType(value, typeof(T)); 9: } 10:  11: return result; 12: } Because T was constrained to be a value type, we can use T? (System.Nullable<T>) where we could not do this if T was a reference type. Constraining Generic Type to Require Default Constructor You can also constrain a type to require existence of a default constructor.  Because by default C# doesn’t know what constructors a generic type placeholder does or does not have available, it can’t typically allow you to call one.  That said, if you give it the new() constraint, it will mean that the type used to realize the generic type must have a default (no argument) constructor. Let’s assume you have a generic adapter class that, given some mappings, will adapt an item from type TFrom to type TTo.  Because it must create a new instance of type TTo in the process, we need to specify that TTo has a default constructor: 1: // Given a set of Action<TFrom,TTo> mappings will map TFrom to TTo 2: public class Adapter<TFrom, TTo> : IEnumerable<Action<TFrom, TTo>> 3: where TTo : class, new() 4: { 5: // The list of translations from TFrom to TTo 6: public List<Action<TFrom, TTo>> Translations { get; private set; } 7:  8: // Construct with empty translation and reverse translation sets. 9: public Adapter() 10: { 11: // did this instead of auto-properties to allow simple use of initializers 12: Translations = new List<Action<TFrom, TTo>>(); 13: } 14:  15: // Add a translator to the collection, useful for initializer list 16: public void Add(Action<TFrom, TTo> translation) 17: { 18: Translations.Add(translation); 19: } 20:  21: // Add a translator that first checks a predicate to determine if the translation 22: // should be performed, then translates if the predicate returns true 23: public void Add(Predicate<TFrom> conditional, Action<TFrom, TTo> translation) 24: { 25: Translations.Add((from, to) => 26: { 27: if (conditional(from)) 28: { 29: translation(from, to); 30: } 31: }); 32: } 33:  34: // Translates an object forward from TFrom object to TTo object. 35: public TTo Adapt(TFrom sourceObject) 36: { 37: var resultObject = new TTo(); 38:  39: // Process each translation 40: Translations.ForEach(t => t(sourceObject, resultObject)); 41:  42: return resultObject; 43: } 44:  45: // Returns an enumerator that iterates through the collection. 46: public IEnumerator<Action<TFrom, TTo>> GetEnumerator() 47: { 48: return Translations.GetEnumerator(); 49: } 50:  51: // Returns an enumerator that iterates through a collection. 52: IEnumerator IEnumerable.GetEnumerator() 53: { 54: return GetEnumerator(); 55: } 56: } Notice, however, you can’t specify any other constructor, you can only specify that the type has a default (no argument) constructor. Summary The where clause is an excellent tool that gives your .NET generics even more power to perform tasks higher than just the base "object level" behavior.  There are a few things you cannot specify with constraints (currently) though: Cannot specify the generic type must be an enum. Cannot specify the generic type must have a certain property or method without specifying a base class or interface – that is, you can’t say that the generic must have a Start() method. Cannot specify that the generic type allows arithmetic operations. Cannot specify that the generic type requires a specific non-default constructor. In addition, you cannot overload a template definition with different, opposing constraints.  For example you can’t define a Adapter<T> where T : struct and Adapter<T> where T : class.  Hopefully, in the future we will get some of these things to make the where clause even more useful, but until then what we have is extremely valuable in making our generics more user friendly and more powerful!   Technorati Tags: C#,.NET,Little Wonders,BlackRabbitCoder,where,generics

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• New York Alt.NET Dinner

  - by Liam McLennan

  While I was in the New York area Stephen Bohlen graciously organised an Alt.NET dinner. I left Rockville Centre on the 17:15 train, thinking I had plenty of time to get to Toloache Mexican Bistro on W 50th St. However, when I changed at Penn Station I took the service downtown, instead of uptown. I corrected that mistake and made it to 51st St, but then ended up in completely the wrong place because I did not understand the street numbering system. For future reference I now have the following rules for NYC navigation: Uptown means North, Downtown means South Streets run East-West, Avenues North-South Street number are symmetrical on the 5th Avenue axis. That is, street numbers increase from zero both east and west of 5th Av. Having gotten totally confused I called Steve, who helped me find the restaurant. I still had my luggage, which we stowed in a corner. Over some descent Mexican food we had some great discussions about Alt.NET, the 2010 conference, and other things of interest to Alt.NET folks. Thanks to Steve for organising and to all the guys who turned up.

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• Differentiating between Hard and Soft Dependencies - Fedora Yum [closed]

  - by Sujit

  I will ask this with an example - I have installed gnash-plugin on fedora 64 bit with Yum. It pulled in following packages - Installing : agg-2.5-9.fc13.x86_64 1/6 Installing : gtkglext-libs-1.2.0-10.fc12.x86_64 2/6 Installing : boost-thread-1.44.0-7.fc14.x86_64 3/6 Installing : boost-date-time-1.44.0-7.fc14.x86_64 4/6 Installing : 1:gnash-0.8.8-4.fc14.x86_64 5/6 Installing : 1:gnash-plugin-0.8.8-4.fc14.x86_64 6/6 Now, I tested the plugin and I didn't like it. I want to remove all these above packages which got installed with the plugin as I don't longer going to need them. How can I do this? I checked remove-with-plugin for yum but it pulls in all the packages which are currently depending on the packages. I understand the thought process behind showing what packages are getting affected - but I am wondering if there is any way of looking at the history with what package got installed when I installed a certain package. When gnash-plugin wasn't there firefox was running fine with but after I installation firefox is now depends on this new plugin. Has any one worked on differentiating hard-dependencies(hard means the program will break if that package is not there) and soft-dependencies ( soft means the program may not get affected fatally) ?

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• Development teams do not scale

  - by Matt Watson

  Recently I have been thinking about how development teams don't scale very well. The bigger a team and the product get, the more time the team spends fixing software bugs. This means they spend more time doing troubleshooting and debugging as the grow. The problem is that since developers don't typically have access to production servers, there is a bottleneck in the process when doing production troubleshooting.For a team that has 10 developers, I would guess than 0-2 of them have access to production servers. If that team grows to 20 people, it is probably the same 0-2 people that have production access still. This means that those 2 key people are a bottleneck and the team does not scale correctly as you add more resources. All those new developers want is to help track down and fix software bugs, but they don't have the visibility to do it. So they end up being less productive and frustrated because they really want to fix the problems. The people who do have production access end up spending too much of their time doing troubleshooting instead of working on new projects.The solution is to remove the bottlenecks and get those people working on more important tasks. Stackify can solve this problem by giving all the developers read only access to production servers. This allows them to access the information they need to do troubleshooting on their own.

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• HLSL - Creating Shadows in 2D

  - by richard

  The way that I create shadows is by the following technique: http://www.catalinzima.com/2010/07/my-technique-for-the-shader-based-dynamic-2d-shadows/ But I have questions to HLSL. The way that I currently do it is, I have a black and white image, where Black means 'object', and white means 'nothing'. I then distort the image like in the tutorial. I do this with a pixel shader, but instead of rendering to the screen, I render to a texture, back to my application. I then take this, and create the shadows, and then send it back to the graphics card to undo the distortion, after the shadow has been added - this comes back and I have a stencil of shadow. I can put this ontop of the original image and send them back to the graphics card, which then puts them on the screen. To me this is alot of back and forth. Is there a way i can avoid this? The problem that I am having is that I need to basically go through all positions in the texture 3 times, and use the new new texture every time instead of the orginal one. I tried to read up on Passes, but i don't think that i am heading in the right direction there. Help?

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• Html 5 ping pong game side collision problem

  - by Gurjit

  I am making a simple ping pong game where I am facing a side collision problem means when the ball collides with the either side of the paddle . Although I have written code for making it works but something is failing....I want plz someone to give suggestions and tell how to avoid it. Means while trying to hit the ball with side face of the paddle poses a problem.!! Here is the main part of the code causing problem function checkCollision(){ ///// This is collision detection for the upper part ///// if( cy + radius >= paddleTop && cx + radius > paddleLeft && cy + radius >= paddleTop + 5 && cx - radius <= paddleLeft + paddleWidth ) { dy = -dy; ++hits; /// On collision we are increasing the Score playSound(); } else if( cy + radius >= paddleTop && cy + radius <= paddleTop + paddleHeight && cx + radius >= paddleLeft && cy - radius <= paddleLeft - (radius + 1) ) { dx = -dx; } } here is working fiddle for it :- http://jsfiddle.net/gurjitmehta/orzpzf69/

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• How can I perform 2D side-scroller collision checks in a tile-based map?

  - by bill

  I am trying to create a game where you have a player that can move horizontally and jump. It's kind of like Mario but it isn't a side scroller. I'm using a 2D array to implement a tile map. My problem is that I don't understand how to check for collisions using this implementation. After spending about two weeks thinking about it, I've got two possible solutions, but both of them have some problems. Let's say that my map is defined by the following tiles: 0 = sky 1 = player 2 = ground The data for the map itself might look like: 00000 10002 22022 For solution 1, I'd move the player (the 1) a complete tile and update the map directly. This make the collision easy because you can check if the player is touching the ground simply by looking at the tile directly below the player: // x and y are the tile coordinates of the player. The tile origin is the upper-left. if (grid[x][y+1] == 2){ // The player is standing on top of a ground tile. } The problem with this approach is that the player moves in discrete tile steps, so the animation isn't smooth. For solution 2, I thought about moving the player via pixel coordinates and not updating the tile map. This will make the animation much smoother because I have a smaller movement unit per frame. However, this means I can't really accurately store the player in the tile map because sometimes he would logically be between two tiles. But the bigger problem here is that I think the only way to check for collision is to use Java's intersection method, which means the player would need to be at least a single pixel "into" the ground to register collision, and that won't look good. How can I solve this problem?

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• MyMessageBox for Phone and Store apps

  - by Daniel Moth

  I am sharing a class I use for both my Windows Phone 8 and Windows Store app projects. Background and my requirements For my Windows Phone 7 projects two years ago I wrote an improved custom MessageBox class that preserves the well-known MessageBox interface while offering several advantages. I documented those and shared it for Windows Phone 7 here: Guide.BeginShowMessageBox wrapper. Aside: With Windows Phone 8 we can now use the async/await feature out of the box without taking a dependency on additional/separate pre-release software. As I try to share code between my existing Windows Phone 8 projects and my new Windows Store app projects, I wanted to preserve the calling code, so I decided to wrap the WinRT MessageDialog class in a custom class to present the same MessageBox interface to my codebase. BUT. The MessageDialog class has to be called with the await keyword preceding it (which as we know is viral) which means all my calling code will also have to use await. Which in turn means that I have to change my MessageBox wrapper to present the same interface to the shared codebase and be callable with await… for both Windows Phone projects and Windows Store app projects. Solution The solution is what the requirements above outlined: a single code file with a MessageBox class that you can drop in your project, regardless of whether it targets Windows Phone 8, or Windows 8 Store apps or both. Just call any of its static Show functions using await and dependent on the overload check the return type to see which button the user chose.// example from http://www.danielmoth.com/Blog/GuideBeginShowMessageBox-Wrapper.aspx if (await MyMessageBox.Show("my message", "my caption", "ok, got it", "that sucks") == MyMessageBoxResult.Button1) { // Do something Debug.WriteLine("OK"); } The class can be downloaded from the bottom of my older blog post. Comments about this post by Daniel Moth welcome at the original blog.

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• How to make a btrfs snapshot?

  - by MountainX

  My /home partition consists of an entire physical disk. It is formatted as btrfs. I want to snapshot it. I'm confused regarding subvolume naming, in particular. I am aware that there are similar questions, but each similar question seems to be asking something different from what I'm asking (and they are older, which means probably outdated, given the rapid development of btrfs). For example, the answer to this question is apparently not the answer to my question because my /home partition is a separate volume and the man page for btrfs shows a different command for creating snapshots now. another similar problem, no solid solution. someone else as confused as me on the naming issues My question: Starting simple: is this the correct command to take a simple snapshot of my home partition? btrfs subvolume snapshot /home/@home /home/@home_snapshot_20120421 I got really brave and tested it and it does not work. The error is error accessing /home/@home. As shown below, @home is listed. I'm obviously confused on subvolume names. Do I need to use them in creating snapshots? Some examples show taking snapshots of home using /home as the source parameter, but based on examples of root volumes, it seems to me that I need to use /home/@home. Would this command work? And if not, why? btrfs subvolume snapshot /home /home/@home_snapshot_20120421 Is the @ just a naming convention? Is it meaningful at all? Here's some output that may be relevant: btrfs subvolume list /home ID 256 top level 5 path @home I'm not sure what that means, exactly. When I try btrfs device scan it gives an error (e.g. unable to scan the device /dev/sda1). My file system doesn't have any errors. Everything is fine.

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• JMX Monitoring of GlassFish Servers

  - by tjquinn

  Did you ever wonder what this message in your GlassFish server.log file means? JMXStartupService has started JMXConnector on JMXService URL service:jmx:rmi://192.168.2.102:8686/jndi/rmi://192.168.2.102:8686/jmxrmi It means you can monitor any GlassFish server process, remotely or locally, using any standard Java Management Extensions (JMX) client.  Examples: jconsole or jvisualvm.   Copy the part of the log message that starts with "service:" into the Add JMX Connection dialog of jvisualvm:  or into the New Connection dialog of jconsole: (The full string is truncated in the on-screen display, but if you copied from the server.log and pasted into the form it should all be there.) The examples above are for a DAS, and your host will probably be different.   The server.log files for other GlassFish servers (instances) will have similar log entries giving the JMX connection string to use for those processes.  Look for the host and/or port to be different. Note a few things about security: Here we've assumed you are using the default admin username and password.  If you are not, just enter a valid admin username and password for your installation.  Once connected, you have normal access to all the JVM statistics and controls. You can use JMX clients that support MBeans to view the GlassFish configuration.  When you connect to the DAS, you can also change that configuration, but you can only view configuration when you connect to an instance. To use a JMX client on one system to connect to a GlassFish server running on another system, you need to enable secure admin if you have not already done so: asadmin change-admin-password (respond to the prompts) asadmin enable-secure-admin asadmin restart-domain (as prompted in the output from enable-secure-admin)

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• Fujitsu Raku-Raku SmartPhone: Japanese Digital Seniors UX Insight from @debralilley

  - by ultan o'broin

  Super blog posting on the super-important subject of digital inclusion by Oracle partner Fujitsu appstech maven and Oracle Applications User Experience FXA-er and ACE Director Debra Lilley (@debralilley). Debra tells us how Fujitsu is enabling digital inclusion for older mobile users in Japan with their  Raku-Raku (??????. ????)smart phone: Fujitsu Raku-Raku - My UX Homework (Raku-Raku means easy or comfortable in Japanese). There are UX mobile, social media, and methodology takeaways there for us in Debra's blog. Fujitsu Raku-Raku Smartphone Demo  I encourage you to read Debra's blog. In it, she makes reference to a tailored social media experience for those digital seniors (???????) as they'd be called in Japan (UK and Ireland uses the term silver surfers). You can find that online experience here. Online Community site for Fujitsu Raku-Raku Smartphone Digital Seniors (English translation via Google Translate) It's an important reminder that UX is global sure, but also that worldwide accessibility and digital inclusion are priorities too for UX. It's vital that we understand such aspects of technology adoption and how the requirements of different categories of technology users can be met. Oracle is committed to providing the best possible user experience for enterprise users of all ages and abilities. That means talking with all sorts of people worldwide and understanding how and why they want to use our technology and what their context of use is. You can read more about Oracle's accessibility program on our corporate website. Proud to say I prompted a few questions in Japan all the way from Ireland. So, UX is not only global but you can drive UX research globally too without ever leaving home. Brilliant job, Debra. Here's to more such joint research creativity and UX collaborations worldwide between us. Wondering where we might go next? And what a fun way to do things too!

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• SubMain Ghost Doc Pro with SpellChecking

  - by TATWORTH

  SubMain have announced at http://community.submain.com/forums/2/1556/ShowThread.aspx#1556 that the next version of GhostDoc will include a VS2005/VS2008/VS2010 compatible spell checker. This replaces their existing spellchecker (http://submain.com/products/codespell.aspx)  which is being discontinued. If you buy GhostDoc Pro now (I urge you to as it helps tremendously in documenting both C# and VB.NET code) , be sure to include Licence Protection as it means you will get the next version that includes the spell-checker free! Why is a spell checker important? By spell checking all your comments, you will make your documentation much easier to read. This means that instead of you being distracted by typographic errors, your mind will be free to see errors in what has been written. Remember the next person that has to struggle to read your code could well be yourself! So be kind to your self. Do the following: Document whole source files in VB.NET of C# with GhostDoc Pro Run Stylecop and fix the issues it uncovers. Run the spellchecker (when it is available) Add remarks where necessary Specify in the project to produce XML documentation Compile the XML using Sandcastle to help files Review the help files and ask yourself if the explanations are sufficient.

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• Oracle Database Appliance and Remarketers - A Whole New Opportunity

  - by Martin Morganti

  We have recently had another exciting announcement for the remarketer initiative. The Oracle Database Appliance is now available for resale through your authorized Value Added Distributor. This means that with no fees, no barriers and no upfront commitments, a remarketer can identify and close transactions for the Oracle Database Appliance without having to sign an Oracle contract. In addition, the remarketer is now authorized to sell the Oracle Database Appliance with Oracle Database 11G Enterprise Edition, RAC or RAC One Node software included in the transaction. The availability of the Oracle Database Appliance for remarketers means that a broad base of customers through remarketers can now start engaging with Oracle by taking advantage of this engineered system technology; basically Oracle Hardware and Software Engineered to Work Together to drive incremental revenue. The Oracle Database Appliance is a simple, reliable and affordable way to rapidly deploy a database cluster by plugging in the power; the network and pushing the one button install for the Appliance Manager software. Find out more about the Oracle Database Appliance, including a webinar by Oracle President Mark Hurd, as well as other material to help you better understand the opportunity available to you as remarketers. If you want Oracle to keep you informed about developments in Remarketer complete the free registration, or talk to your local Oracle Remarketer Authorized value added distributors. (Complete list available on the Oracle Remarketer page).

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• The premier support for Sun Cluster 3.1 ended

  - by JuergenS

  In October 2011 the premier support for Sun Cluster 3.1 ended. See details in Oracle Lifetime Support Policy for Oracle and Sun System Software document. There no 'Extended Support' and the 'Sustaining Support Ends' is indefinite. But for indefinite 'Sustaining Support' I like to point out from the mentioned document (version Sept. 2011) on page 5: Sustaining Support does NOT include: * New program updates, fixes, security alerts, general maintenance releases, selected functionality releases and documentation updates or upgrade tools * Certification with most new third-party products/versions and most new Oracle products * 24 hour commitment and response guidelines for Severity 1 service requests *Previously released fixes or updates that Oracle no longer supports This means Solaris 10 9/10 update9 is the last qualified release for Sun Cluster 3.1. So, Sun Cluster 3.1 is not qualified on Solaris 10 8/11 Update10. Furthermore there is an issue around with SVM patch 145899-06 or higher. This SVM patch is part of Solaris 10 8/11 Update10. The 145899-06 is the first released patch of this number, therefore the support for Sun Cluster 3.1 ends with the previous SVM patches 144622-01 and 139967-02. For details about the known problem with SVM patch 145899-06 please refer to doc 1378828.1. Further this means you should freeze (no patching, no upgrade) your Sun Cluster 3.1 configuration not later than Solaris 10 9/10 update9. Or even better plan an upgrade to Solaris Cluster 3.3 now to get back to full support.

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• Google ranking, page crawl

  - by Nawaf Mubarak

  please don't mind me for asking this newbie question about Google ranking. I know that in order to get ranked the page has to be crawled by Google bots, I have had a page example of which I will get a better understanding of how the system works with Google. I have made a page on my website last month, it got indexed pretty quickly, then I found that it's in Google's page 15 on my keyword as a start, next day it made it to page 13, then after a week it was jumping back and forth in page 17/18 up to 20. Now a month passed by, when and it isn't listed in any position of that 'keyword' sometimes I will find it in page 30, but later I won't find it anywhere, keep happening this way these days. Even if it isn't listed in any page for my keyword if I do a search for "site:thepageadress" it will be listed which means I'm not penalized and my page is there for google to see, but it isn't in the search result for my keyword. But when I write "site:thepage_adress" and I hit "search tools" option and click on "Past day" or "past week" it isn't listed, it is only listed when I click on "Past month" which I think means that Google indexed the page, looked at it once when I published it, and never looked at it again, is this a fair statement? So two questions that comes to mind here. 1- Should Google keep looking at a page even if I haven't changed any info for it? and is this an indication for me that my page is doing fine? or is it normal that Google see's it once and thats it? 2- Why and how to fix the fact that my page keeps jumping back and forth in the ranking result for keyword, and sometimes it isn't even listed, what does that mean? Sorry for the long msg, I hope to god that somebody help me with this. Thank you!

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• Making simple forms in web applications

  - by levalex

  How do you work with forms in your web applications? I am not talking about RESTful applications, I don't want to build heavy front-end using frameworks like Backbone. For example, I need to add "contact us" form. I need to check data which was filled by user and tell him that his data was sent. Requirements: I want to use AJAX. I want to validate form on back-end side and don't want to duplicate the same code on front-end side. I have my own solution, but it doesn't satisfy me. I make an AJAX request with serialized data on form submit and get response. The next is checking "Content-type" header. html - It means that errors with filling form are exists and response html is form with error labels. - I will replace my form with response html. json and response.error_code == 0 - It means that form was successfully submited. - I will show user notification about success. json and response.error_code != 0 - Something was broken on back-end (like connection with database). other - I display the following message : We have been notified and have started to work with that problem. Please, try it later. The problem of that way is that I can't use it with forms that upload file. What is your practise? What libraries and principles do you use?

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• Understanding Box2d Restitution & Bouncing

  - by layzrr

  I'm currently trying to implement basketball bouncing into my game using Box2d (jBox2d technically), but I'm a bit confused about restitution. While trying to create the ball in the testbed first, I've run into infinite bouncing, as described in this question, however obviously not using my own implementation. The Box2d manual describes restitution as follows: Restitution is used to make objects bounce. The restitution value is usually set to be between 0 and 1. Consider dropping a ball on a table. A value of zero means the ball won't bounce. This is called an inelastic collision. A value of one means the ball's velocity will be exactly reflected. This is called a perfectly elastic collision. My confusion lies in that I am still getting infinite bouncing with restitution values at 0.75/0.8. The same behavior can be seen in the testbed under Collision Watching - Varying Restitution, on the 6th and 7th balls. I believe the last one has restitution of 1, which makes sense, but I don't understand why the second to last ball bounces infinitely (as is happening with my working basketball I've created). I am looking to understand the restitution concept more fully, as well as look for a solution to infinite bouncing with the Box2d framework. My instinct was to sleep objects that appeared to be moving in very small increments, but this seems like a misuse of the engine. Should I just work with lower restitution values altogether?

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• Is my concept in open source license correct?

  - by tester

  I would like to justify whether my concept in the open source license is correct, as you know that, misunderstanding the terms may lead to a serious law sue. Thank you. The main difference among the open source license is whether the license is copyleft. Copyleft license means allow the others to reproduce, modify and distribute the products but the released product is bound by the same licensing restriction. That means they have to use the same license for the modified version. Also, the copyleft license require all the released modified version to be free software. On the other hand, if any others create derived work incorporating non-copyleft licensed code, they can choose any license for the code. The serveral kinds of license and comparsion GPL is a restrictive license. Software requires to released as GPL license if that integrate or is modified from the other GPL license software . The library used in developing GPL license software are also restricted to GPL and LGPL , proprietary software are not allowed to employ (or complied with) in any part of the GPL application. LGPL is similar to GPL , but was more permissive with regarding allow the using of other non-GPL software. BSD is relatively simple license, it allow developer to do anything on the original source code . The license holder do not hold any legal responsibilities for their released product. Apache license is evolved from the BSD license. The legal terms are improved and are written by legal professionals in a more modern way. It covers comprehensive intellectual property ownership and liability issues. Also, are there any popular license beside these? Thank you

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• Building Enterprise Smartphone App &ndash; Part 4: Application Development Considerations

  - by Tim Murphy

  This is the final part in a series of posts based on a talk I gave recently at the Chicago Information Technology Architects Group.  Feel free to leave feedback. Application Development Considerations Now we get to the actual building of your solutions.  What are the skills and resources that will be needed in order to develop a smartphone application in the enterprise? Language Knowledge One of the first things you need to consider when you are deciding which platform language do you either have the most in house skill base or can you easily acquire.  If you already have developers who know Java or C# you may want to use either Android or Windows Phone.  You should also take into consideration the market availability of developers.  If your key developer leaves how easy is it to find a knowledgeable replacement? A second consideration when it comes to programming languages is the qualities exposed by the languages of a particular platform.  How well does that development language and its associated frameworks support things like security and access to the features of the smartphone hardware?  This will play into your overall cost of ownership if you have to create this infrastructure on your own. Manage Limited Resources Everything is limited on a smartphone: battery, memory, processing power, network bandwidth.  When developing your applications you will have to keep your footprint as small as possible in every way.  This means not running unnecessary processes in the background that will drain the battery or pulling more data over the airwaves than you have to.  You also want to keep your on device in as compact a format as possible. Mobile Design Patterns There are a number of design patterns that have either come to life because of smartphone development or have been adapted for this use.  The main pattern in the Windows Phone environment is the MVVM (Model-View-View-Model).  This is great for overall application structure and separation of concerns.  The fun part is trying to keep that separation as pure as possible.  Many of the other patterns may or may not have strict definitions, but some that you need to be concerned with are push notification, asynchronous communication and offline data storage. Real estate is limited on smartphones and even tablets. You are also limited in the type of controls that can be represented in the UI. This means rethinking how you modularize your application. Typing is also much harder to do so you want to reduce this as much as possible.  This leads to UI patterns.  While not what we would traditionally think of as design patterns the guidance each platform has for UI design is critical to the success of your application.  If user find the application difficult navigate they will not use it. Development Process Because of the differences in development tools required, test devices and certification and deployment processes your teams will need to learn new way of working together.  This will include the need to integrate service contracts of back-end systems with mobile applications.  You will also want to make sure that you present consistency across different access points to corporate data.  Your web site may have more functionality than your smartphone application, but it should have a consistent core set of functionality.  This all requires greater communication between sub-teams of your developers. Testing Process Testing of smartphone apps has a lot more to do with what happens when you lose connectivity or if the user navigates away from your application. There are a lot more opportunities for the user or the device to perform disruptive acts.  This should be your main testing concentration aside from the main business requirements.  You will need to do things like setting the phone to airplane mode and seeing what the application does in order to weed out any gaps in your handling communication interruptions. Need For Outside Experts Since this is a development area that is new to most companies the need for experts is a lot greater. Whether these are consultants, vendor representatives or just development community forums you will need to establish expert contacts. Nothing is more dangerous for your project timelines than a lack of knowledge.  Make sure you know who to call to avoid lengthy delays in your project because of knowledge gaps. Security Security has to be a major concern for enterprise applications. You aren't dealing with just someone's game standings. You are dealing with a companies intellectual property and competitive advantage. As such you need to start by limiting access to the application itself.  Once the user is in the app you need to ensure that the data is secure at all times.  This includes both local storage and across the wire.  This means if a platform doesn’t natively support encryption for these functions you will need to find alternatives to secure your data.  You also need to keep secret (encryption) keys obfuscated or locked away outside of the application. People can disassemble the code otherwise and break your encryption. Offline Capabilities As we discussed earlier one your biggest concerns is not having connectivity.  Because of this a good portion of your code may be dedicated to handling loss of connection and reconnection situations.  What do you do if you lose the network?  Back up all your transactions and store of any supporting data so that operations can continue off line. In order to support this you will need to determine the available flat file or local data base capabilities of the platform.  Any failed transactions will need to support a retry mechanism whether it is automatic or user initiated.  This also includes your services since they will need to be able to roll back partially completed transactions.  What ever you do, don’t ignore this area when you are designing your system. Deployment Each platform has different deployment capabilities. Some are more suited to enterprise situations than others. Apple's approach is probably the most mature at the moment. Prior to the current generation of smartphone platforms it would have been Windows CE. Windows Phone 7 has the limitation that the app has to be distributed through the same network as public facing applications. You mark them as private which means that they are only accessible by a direct URL. Unfortunately this does not make them undiscoverable (although it is very difficult). This will change with Windows Phone 8 where companies will be able to certify their own applications and distribute them.  Given this Windows Phone applications need to be more diligent with application access in order to keep them restricted to the company's employees. My understanding of the Android deployment schemes is that it is much less standardized then either iOS or Windows Phone. Someone would have to confirm or deny that for me though since I have not yet put the time into researching this platform further. Given my limited exposure to the iOS and Android platforms I have not been able to confirm this, but there are varying degrees of user involvement to install and keep applications updated. At one extreme the user just goes to a website to do the install and in other case they may need to download files and perform steps to install them. Future Bluetooth Today we use Bluetooth for keyboards, mice and headsets.  In the future it could be used to interrogate car computers or manufacturing systems or possibly retail machines by service techs.  This would open smartphones to greater use as a almost a Star Trek Tricorder.  You would get you all your data as well as being able to use it as a universal remote for just about any device or machine. Better corporation controlled deployment At least in the Windows Phone world the upcoming release of Windows Phone 8 will include a private certification and deployment option that is currently not available with Windows Phone 7 (Mango). We currently have to run the apps through the Marketplace certification process and use a targeted distribution method. Platform independent approaches HTML5 and JavaScript with Web Service has become a popular topic lately for not only creating flexible web site, but also creating cross platform mobile applications.  I’m not yet convinced that this lowest common denominator approach is viable in most cases, but it does have it’s place and seems to be growing.  Be sure to keep an eye on it. Summary From my perspective enterprise smartphone applications can offer a great competitive advantage to many companies.  They are not cheap to build and should be approached cautiously.  Understand the factors I have outlined in this series, do you due diligence and see if there is a portion of your business that can benefit from the mobile experience. del.icio.us Tags: Architecture,Smartphones,Windows Phone,iOS,Android

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• starting up with VPS or cloud hosting? [closed]

  - by FlyOn

  Possible Duplicate: How to find web hosting that meets my requirements? Summary: I want to start hosting my product. I'd like to register domains (at some point). I'm a linux beginner. Thinking about scalability and price, I'm thinking am I better off on a VPN to get started or would some form of cloud hosting be better (not being familiar with either). Full question: I'm creating a product where people can create their own 3D representations of whatever data / info they have, and (re)organise that data. The product is coming along beautifully on my local environment, but it's about time I start getting some form of hosting ready, and I could really use some advice where / how to get started: I'd like people to be able to move/register their own domains on my server. I could start without this just to demo the product, but it would be the very first on the todo list. I'd like to automatically copy some files / install databases etc for each domain. I probably want to see if I can let users manage their own subdomains at some points, but for now: I'd like start as simple as possible. I've always on a windows machine, so my linux experience is quite basic. I really don't mind getting into it, but I'm thinking it's better to get my product out first of all and see where to go from there. Although... I'd like things to be scalable. If I set up some reseller VPN now which only scales to 100 domains or so, which means I have to set up something else / move again when I pass that level, or which means that I'm in trouble if I suddenly get lots of new customers... hmm. Finally, I need to start cheap. I'm putting all I have into starting this company, and live on very little. So before I have any customers, 50 dollars a month is a fair bit and 100 dollars a month may be too much. If anyone has some tips to help get me started I'd be really grateful.

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• ZFS Basics

  - by user12614620

  Stage 1 basics: creating a pool # zpool create $NAME $REDUNDANCY $DISK1_0..N [$REDUNDANCY $DISK2_0..N]... $NAME = name of the pool you're creating. This will also be the name of the first filesystem and, by default, be placed at the mountpoint "/$NAME" $REDUNDANCY = either mirror or raidzN, and N can be 1, 2, or 3. If you leave N off, then it defaults to 1. $DISK1_0..N = the disks assigned to the pool. Example 1: zpool create tank mirror c4t1d0 c4t2d0 name of pool: tank redundancy: mirroring disks being mirrored: c4t1d0 and c4t2d0 Capacity: size of a single disk Example 2: zpool create tank raidz c4t1d0 c4t2d0 c4t3d0 c4t4d0 c4t5d0 Here the redundancy is raidz, and there are five disks, in a 4+1 (4 data, 1 parity) config. This means that the capacity is 4 times the disk size. If the command used "raidz2" instead, then the config would be 3+2. Likewise, "raidz3" would be a 2+3 config. Example 3: zpool create tank mirror c4t1d0 c4t2d0 mirror c4t3d0 c4t4d0 This is the same as the first mirror example, except there are two mirrors now. ZFS will stripe data across both mirrors, which means that writing data will go a bit faster. Note: you cannot create a mirror of two raidzs. You can create a raidz of mirrors, but to do that requires trickery.

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• CA For A Large Intranet

  - by Tim Post

  I'm managing what has become a very large intranet (over 100 different hosts / services) and will be stepping down from my role in the near future. I want to make things easy for the next victim person who takes my place. All hosts are secured via SSL. This includes various portals, wikis, data entry systems, HR systems and other sensitive things. We're using self signed certificates which worked o.k. in the past, but are now problematic because: Browsers make it harder for users to understand exactly what is going on when a self signed certificate is encountered, much less accept them. Putting up a new host means 100 phone calls asking what "Add an exception" means What we were doing is just importing the self signed certs when we set up a new workstation. This was fine when we only had a dozen to deal with, but now its just overwhelming. Our I.T. Department has classified this as ya all's problem, all we get from them is support for switch and router configurations. Beyond the user having connectivity, everything else is up to the intranet administrators. We have a mix of Ubuntu and Windows workstations. We'd like to set up our own self signed CA root, which can sign certificates for each host that we deploy on the intranet. Client browsers would of course be told to trust our CA. My question is, would this be dangerous and would we be better off going with intermediate certificates from someone like Verisign? Either way, I still have to import the root for the intermediate CA, so I really don't see what the difference is? Other than charging us money, what would Verisign be doing that we could not, beyond protecting the root CA cert so it can't be used to make forgeries?

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• Is realtime validation of username good or bad?

  - by iamserious

  I have a simple form for the user to sign up to my site; with email, username and password fields. We are now trying to implement an ajax validation so the user doesn't have to post the form to find out if the username is already taken. I can do this either on keyup event or on text blur event. My question is, which of these is really the best way to do? Keyup From the user POV, it would be good if the validation is done as and when they are typing, (on key up event) - of course, I am waiting for half a second to see if the user stops typing before firing off the request, and user can make any adjustments immediately. But this means I am sending way more requests than if I validated the username on Blur event. Blur The number of requests will be much lower when the validation is done on blur event, But this means the user has to actually go away from the textbox, look at the validation result, and if necessary go back to it to make any changes and repeat the whole process until he gets it right. I had a quick look at google, tumblr, twitter and no one actually does username validations on keyup events, (heck, tubmlr waits for the form to be posted) but I can swear I have seen keyup validations in a lot of places too. So, coming back to the question, will keyup validations be too many for server, is it an unnecessary overhead? or is it worth taking these hits to give user a better experience? ps: all my regex validations etc are already done on javascript and only when it passes all these other criteria does it send a request to server to check if a username already exists. (And the server is doing a select count(1) from user where username = '' - nothing substantial, but still enough to occupy some resource) pps: I'm on asp.net, MS SQL stack., if that matters.

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