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• JavaOne Session Report - Java ME SDK 3.2

  - by Janice J. Heiss

  Oracle Product Manager for Java ME SDK, Sungmoon Cho, presented a session, "Developing Java Mobile and Embedded Applications with Java ME SDK 3.2,” wherein he covered the basic new features of the Java ME Platform SDK 3.2, a state-of-the-art toolbox for developing mobile and embedded applications. The session began with a summary of the four main components of Java ME SDK. A device emulator allows developers to quickly run and test applications before commercialization. It supports CLDC/MIDP CLDC/IMP.NG and CLC/AGUI. A development environment assists writing, running debugging and deploying and enables on-device debugging. Samples provide developers with useful codes and frameworks. IDE Plugins – NetBeans and Eclipse – equip developers with CPU Profiler, Memory Monitor, Network Monitor, and Device Selector. This means that manual integration is no longer necessary. Cho then talked about the Java ME SDK’s on-device tooling architecture: * Java ME SDK provides an architecture ideal for on-device-debugging.* Device Manager plays the central role by managing different devices whether it is the emulator or a device that Oracle provides or recommends or a third party device as long as the devices have a Java Runtime that supports the protocol that is designated.* The Emulator provides an accurate emulation, since it uses the same code base used in Oracle’s Java ME runtime.* The Universal Emulator Interface (UEI) makes it easy for IDEs to detect the platform.He then focused on the Java ME SDK release highlights, which include: * Implementation and support for the new Oracle® Java Wireless Client 3.2 runtime and the Oracle® Java ME Embedded runtime. A full emulation for the runtime is provided.* Support for JSR 228, the Information Module Profile-Next Generation API (IMP-NG). This is a new profile for embedded devices. * A new Custom Device Skin Creator.* An Eclipse plugin for CLDC/MIDP.* Profiling, Network monitoring, and Memory monitoring are now integrated with the NetBeans profiling tools.* Java ME SDK Update CenterCho summarized the main features: IDE Integration (NetBeans and Eclipse) enables developers to write, run, profile, and debug their applications on their favorite IDE. CPU ProfilerThis enables developers to more quickly detect the hot spot and where CPU time is being used. They can double click the method to jump directly into the source code.Memory Monitor Developers can monitor objects and memory usage in real time.Debugger on the Emulator and DeviceDevelopers can run their applications step by step, and inspect the variables to pinpoint the problem. The debugging can take place either on the emulator or the device.Embedded Application DevelopmentIMP-NG, Device Access, Logging, and AMS API Support are now available.On-Device ToolingConnect your device to your computer, and run and debug the application right on your device.Custom Device Skin CreatorDefine your own device and test on an environment that is closest to your target device. The informative session concluded with a demo that showed more concretely how to apply the new features in Java ME SDK 3.2.

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• Brain Teaser: How Did I Do This (Part 1: The Solution)

  - by Geertjan

  In Part 1: The Challenge, published this time last week, I introduced a "brain teaser". The brain teaser asks you to figure out how to allow images and other files to be meaningfully dropped onto a NetBeans Platform application, i.e., on the drop something useful should happen with the dropped file: if the file is an image, the image should open in the IDE; if the file is a PDF document, the PDF viewer should open externally; if the file is a text file, it should open as a text in the IDE, etc. Solution. And here is the solution: http://bits.netbeans.org/dev/javadoc/org-openide-windows/org/openide/windows/ExternalDropHandler.html When an implementation of the "ExternalDropHandler" class is available in the global Lookup, and an object is being dragged over some part of the main window, the window system may call the methods of this class to decide whether it can accept or reject the drag operation. And when the object is actually dropped, this class will be asked to handle the drop. OK, so go ahead and implement the above class and put it into the Lookup. Or... guess what? The NetBeans Platform has a default implementation of the above class, appropriately named "DefaultExternalDropHandler". Not only is this useful to learn about how to implement the ExternalDropHandler class (i.e., by reading the source here): you can simply include the module that contains this class in your own NetBeans Platform application and then your application will be able to receive external drag/drop events and do something meaningful with them thanks to the DefaultExternalDropHandler. Do this: Open your NetBeans Platform application in NetBeans IDE. Right-click the application in the Projects window and choose Properties. In the Libraries tab, expand the "ide" cluster, and select "User Utilities". (That's where "DefaultExternalDropHandler.java" is found and registered in the Lookup.) Now click the "Resolve" button, if it appears, because some additional related modules need to now be included, if they haven't been included yet. Again in the "ide" cluster in the Libraries tab, select "Image". That's the Image Editor. Click OK. Run the application. Drag an image or some other type of file into your application, from outside the application, and you'll see the application tries to handle the drop. If the file being dragged is an image, it will open in the Image Editor, which you included in the previous step of these instructions. Hurray, you're done. Without any programming at all, you've added a cool new feature to your application.

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• Draw images with warped triangles on a web server [migrated]

  - by epologee

  The scenario The Flash front end of my current project produces images that a web server needs to combine into a video. Both frame-rate and frame-resolution are sizeable enough that sending an image sequence to the back end is not feasible (in both time and client bandwidth). Instead, we're trying to recreate the image drawing on the back end as well. Correct and slow, or incorrect and fast The problem is that this involves quite a bit of drawing textured triangles, and two solutions we found in Python (here and there) are so inefficient, that the drawing takes about 60 seconds per frame, resulting in a whopping 7,5 hours of processing time for a 30 second clip. Unacceptable. When using a PHP-module to send commands to ImageMagick for image manipulation, the whole process is super fast (tenths of a second per frame), but ImageMagick seems to be unable to draw triangles the way we do it in the front end, so the final results do not match. Unacceptable. What I'm asking here, is if there's someone who would know a way to solve this issue, by any means necessary that would run on a web server. Warping an image Let me explain the process of the front end: Perform a Delaunay calculation on points in an image to get an evenly distributed mesh of triangles. Offset the points/vertices in the mesh, distorting or warping the image. Draw the warped triangles on a new bitmap. We can send the results (coordinates) of steps 1 and 2 to the back end, to then draw the warped triangles and save it to an image on disk (or append as a frame to the video). But that last step is what I need help with. The Question Is there an alternative to ImageMagick that can draw triangles in a bitmap? Is there some other library, like a C library, that would allow us to do this? Or could we achieve this effect more easily by switching back end technologies, like Ruby? (.Net and Java are, unfortunately, not really options right now) Many thanks. EP. P.S. I'd appreciate re-tagging efforts, I don't quite know what labels to put on this question. Thanks!

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• Hopping/Tumbling Windows Could Introduce Latency.

  This is a pre-article to one I am going to be writing on adjusting an event’s time and duration to satisfy business process requirements but it is one that I think is really useful when understanding the way that Hopping/Tumbling windows work within StreamInsight.  A Tumbling window is just a special shortcut version of  a Hopping window where the width of the window is equal to the size of the hop Here is the simplest and often used definition for a Hopping Window.  You can find them all here public static CepWindowStream<CepWindow<TPayload>> HoppingWindow<TPayload>(     this CepStream<TPayload> source,     TimeSpan windowSize,     TimeSpan hopSize,     WindowInputPolicy inputPolicy,     HoppingWindowOutputPolicy outputPolicy )   And here is the definition for a Tumbling Window public static CepWindowStream<CepWindow<TPayload>> TumblingWindow<TPayload>(     this CepStream<TPayload> source,     TimeSpan windowSize,     WindowInputPolicy inputPolicy,     HoppingWindowOutputPolicy outputPolicy )   These methods allow you to group events into windows of a temporal size.  It is a really useful and simple feature in StreamInsight.  One of the downsides though is that the windows cannot be flushed until an event in a following window occurs.  This means that you will potentially never see some events or see them with a delay.  Let me explain. Remember that a stream is a potentially unbounded sequence of events. Events in StreamInsight are given a StartTime.  It is this StartTime that is used to calculate into which temporal window an event falls.  It is best practice to assign a timestamp from the source system and not one from the system clock on the processing server.  StreamInsight cannot know when a window is over.  It cannot tell whether you have received all events in the window or whether some events have been delayed which means that StreamInsight cannot flush the stream for you.   Imagine you have events with the following Timestamps 12:10:10 PM 12:10:20 PM 12:10:35 PM 12:10:45 PM 11:59:59 PM And imagine that you have defined a 1 minute Tumbling Window over this stream using the following syntax var HoppingStream = from shift in inputStream.TumblingWindow(TimeSpan.FromMinutes(1),HoppingWindowOutputPolicy.ClipToWindowEnd) select new WindowCountPayload { CountInWindow = (Int32)shift.Count() };   The events between 12:10:10 PM and 12:10:45 PM will not be seen until the event at 11:59:59 PM arrives.  This could be a real problem if you need to react to windows promptly This can always be worked around by using a different design pattern but a lot of the examples I see assume there is a constant, very frequent stream of events resulting in windows always being flushed. Further examples of using windowing in StreamInsight can be found here

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• PCI Encryption Key Management

  - by Unicorn Bob

  (Full disclosure: I'm already an active participant here and at StackOverflow, but for reasons that should hopefully be obvious, I'm choosing to ask this particular question anonymously). I currently work for a small software shop that produces software that's sold commercially to manage small- to mid-size business in a couple of fairly specialized industries. Because these industries are customer-facing, a large portion of the software is related to storing and managing customer information. In particular, the storage (and securing) of customer credit card information. With that, of course, comes PCI compliance. To make a long story short, I'm left with a couple of questions about why certain things were done the way they were, and I'm unfortunately without much of a resource at the moment. This is a very small shop (I report directly to the owner, as does the only other full-time employee), and the owner doesn't have an answer to these questions, and the previous developer is...err...unavailable. Issue 1: Periodic Re-encryption As of now, the software prompts the user to do a wholesale re-encryption of all of the sensitive information in the database (basically credit card numbers and user passwords) if either of these conditions is true: There are any NON-encrypted pieces of sensitive information in the database (added through a manual database statement instead of through the business object, for example). This should not happen during the ordinary use of the software. The current key has been in use for more than a particular period of time. I believe it's 12 months, but I'm not certain of that. The point here is that the key "expires". This is my first foray into commercial solution development that deals with PCI, so I am unfortunately uneducated on the practices involved. Is there some aspect of PCI compliance that mandates (or even just strongly recommends) periodic key updating? This isn't a huge issue for me other than I don't currently have a good explanation to give to end users if they ask why they are being prompted to run it. Question 1: Is the concept of key expiration standard, and, if so, is that simply industry-standard or an element of PCI? Issue 2: Key Storage Here's my real issue...the encryption key is stored in the database, just obfuscated. The key is padded on the left and right with a few garbage bytes and some bits are twiddled, but fundamentally there's nothing stopping an enterprising person from examining our (dotfuscated) code, determining the pattern used to turn the stored key into the real key, then using that key to run amok. This seems like a horrible practice to me, but I want to make sure that this isn't just one of those "grin and bear it" practices that people in this industry have taken to. I have developed an alternative approach that would prevent such an attack, but I'm just looking for a sanity check here. Question 2: Is this method of key storage--namely storing the key in the database using an obfuscation method that exists in client code--normal or crazy? Believe me, I know that free advice is worth every penny that I've paid for it, nobody here is an attorney (or at least isn't offering legal advice), caveat emptor, etc. etc., but I'm looking for any input that you all can provide. Thank you in advance!

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• How to place rooms proceduraly (rule based) on in a game word

  - by gardian06

  I am trying to design the algorithm for my level generation which is a rule driven system. I have created all the rules for the system. I have taken care to insure that all rooms make sense in a grid type setup. for example: these rooms could make this configuration The logic flow code that I have so far Door{ Vector3 position; POD orient; // 5 possible values (up is not an option) bool Open; } Room{ String roomRule; Vector3 roomPos; Vector3 dimensions; POD roomOrient; // 4 possible values List doors<Door>; } LevelManager{ float scale = 18f; List usedRooms<Room>; List openDoors<Door> bool Grid[][][]; Room CreateRoom(String rule, Vector3 position, POD Orient){ place recieved values based on rule fill in other data } Vector3 getDimenstions(String rule){ return dimensions of the room } RotateRoom(POD rotateAmount){ rotate all items in the room } MoveRoom(Room toBeMoved, POD orientataion, float distance){ move the position of the room based on inputs } GenerateMap(Vector3 size, Vector3 start, Vector3 end){ Grid = array[size.y][size.x][size.z]; Room floatingRoom; floatingRoom = Room.CreateRoom(S01, start, rand(4)); usedRooms.Add(floatingRoom); for each Door in floatingRoom.doors{ openDoors.Add(door); } // fill used grid spaces floatingRoom = Room.CreateRoom(S02, end, rand(4); usedRooms.Add(floatingRoom); for each Door in floatingRoom.doors{ openDoors.Add(door); } Vector3 nRoomLocation; Door workingDoor; string workingRoom; // fill used grid spaces // pick random door on the openDoors list workingDoor = /*randomDoor*/ // get a random rule nRoomLocation = workingDoor.position; // then I'm lost } } I know that I have to make sure for convergence (namely the end is reachable), and to do this until there are no more doors on the openDoors list. right now I am simply trying to get this to work in 2D (there are rules that introduce 3D), but I am working on a presumption that a rigorous algorithm can be trivially extended to 3D. EDIT: my thought pattern so far is to take an existing open door and then pick a random room (restrictions can be put in later) place that room's center at the doors location move the room in the direction of the doors orientation half the rooms dimension w/respect to that axis then test against the 3D array to see if all the grid points are open, or have been used, or if there is even space to put the room (caseEdge) if caseEdge (which can also occur in between rooms) then put the door on a toBeClosed list, and remove it from the open list (placing a wall or something there). then to do some kind of test that both the start, and the goal are connected, and reachable from each other (each room has nodes for AI, but I don't want to "have" to pull those out to accomplish this). but this logic has the problem for say the U, or L shaped rooms in my example, and then I also have a problem conceptually if the room needs to be rotated.

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• How to deal with fellow programmer who likes to delegate task with lack any support from boss [closed]

  - by Rudy

  I have a problem with my fellow programmer. We are currently working together in a small project that need to be shipped every 2 weeks. She has a tendency to ask for help for every issues that she is facing. Whether it's a compile error, algorithm problem or even sync/merge issue that caused by herself. She does not even bother to check Google or try to find out by herself. I can be asked to help her for 5-10 times a day. Everyday her husband keeps calling (4-6 times a day), and most of the code that has been delivered by her are actually incorrect. Today she framed me for sending the wrong delivery product. She went home after lunch on the delivery day without telling PM and other team member on that day and her code she commited does not work at all. It's not even tested. I have no choice to roll back her code and cleaning her code just for sake to able to run the product. I have warned her about her defective codes for almost 3 iterations. She said when she was not around I should be able to test her module for her. I snapped and yelled that I am not her slave and directly reported to my boss. However, my boss is not a person that can manage and care about software quality. What is the most important thing to my boss is delivery of product, whether it tested or not. He can even asked us to deliver something that not even tested by QA to the client, on the next day. Most of our suggestion is not followed by him. He even asked me to apologize to her because I snapped. I am tired of the whole situation. This kind of thing keeps repeated. I do have saving to be able to survive for 6 months and the idea of resigning is keep haunting. There is nothing else that can be learned in my current job and I had been in a better environment than this. What should I do with the situation?

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• Webcast On-Demand: Building Java EE Apps That Scale

  - by jeckels

  With some awesome work by one of our architects, Randy Stafford, we recently completed a webcast on scaling Java EE apps efficiently. Did you miss it? No problem. We have a replay available on-demand for you. Just hit the '+' sign drop-down for access.Topics include: Domain object caching Service response caching Session state caching JSR-107 HotCache and more! Further, we had several interesting questions asked by our audience, and we thought we'd share a sampling of those here for you - just in case you had the same queries yourself. Enjoy! What is the largest Coherence deployment out there? We have seen deployments with over 500 JVMs in the Coherence cluster, and deployments with over 1000 JVMs using the Coherence jar file, in one system. On the management side there is an ecosystem of monitoring tools from Oracle and third parties with dashboards graphing values from Coherence's JMX instrumentation. For lifecycle management we have seen a lot of custom scripting over the years, but we've also integrated closely with WebLogic to leverage its management ecosystem for deploying Coherence-based applications and managing process life cycles. That integration introduces a new Java EE archive type, the Grid Archive or GAR, which embeds in an EAR and can be seen by a WAR in WebLogic. That integration also doesn't require any extra WebLogic licensing if Coherence is licensed. How is Coherence different from a NoSQL Database like MongoDB? Coherence can be considered a NoSQL technology. It pre-dates the NoSQL movement, having been first released in 2001 whereas the term "NoSQL" was coined in 2009. Coherence has a key-value data model primarily but can also be used for document data models. Coherence manages data in memory currently, though disk persistence is in a future release currently in beta testing. Where the data is managed yields a few differences from the most well-known NoSQL products: access latency is faster with Coherence, though well-known NoSQL databases can manage more data. Coherence also has features that well-known NoSQL database lack, such as grid computing, eventing, and data source integration. Finally Coherence has had 15 years of maturation and hardening from usage in mission-critical systems across a variety of industries, particularly financial services. Can I use Coherence for local caching? Yes, you get additional features beyond just a java.util.Map: you get expiration capabilities, size-limitation capabilities, eventing capabilites, etc. Are there APIs available for GoldenGate HotCache? It's mostly a black box. You configure it, and it just puts objects into your caches. However you can treat it as a glass box, and use Coherence event interceptors to enhance its behavior - and there are use cases for that. Are Coherence caches updated transactionally? Coherence provides several mechanisms for concurrency control. If a project insists on full-blown JTA / XA distributed transactions, Coherence caches can participate as resources. But nobody does that because it's a performance and scalability anti-pattern. At finer granularity, Coherence guarantees strict ordering of all operations (reads and writes) against a single cache key if the operations are done using Coherence's "EntryProcessor" feature. And Coherence has a unique feature called "partition-level transactions" which guarantees atomic writes of multiple cache entries (even in different caches) without requiring JTA / XA distributed transaction semantics.

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• Is there any kind of established architecture for browser based games?

  - by black_puppydog

  I am beginning the development of a broser based game in which players take certain actions at any point in time. Big parts of gameplay will be happening in real life and just have to be entered into the system. I believe a good kind of comparison might be a platform for managing fantasy football, although I have virtually no experience playing that, so please correct me if I am mistaken here. The point is that some events happen in the program (i.e. on the server, out of reach for the players) like pulling new results from some datasource, starting of a new round by a game master and such. Other events happen in real life (two players closing a deal on the transfer of some team member or whatnot - again: have never played fantasy football) and have to be entered into the system. The first part is pretty easy since the game masters will be "staff" and thus can be trusted to a certain degree to not mess with the system. But the second part bothers me quite a lot, especially since the actions may involve multiple steps and interactions with different players, like registering a deal with the system that then has to be approved by the other party or denied and passed on to a game master to decide. I would of course like to separate the game logic as far as possible from the presentation and basic form validation but am unsure how to do this in a clean fashion. Of course I could (and will) put some effort into making my own architectural decisions and prototype different ideas. But I am bound to make some stupid mistakes at some point, so I would like to avoid some of that by getting a little "book smart" beforehand. So the question is: Is there any kind of architectural works that I can read up on? Papers, blogs, maybe design documents or even source code? Writing this down this seems more like a business application with business rules, workflows and such... Any good entry points for that? EDIT: After reading the first answers I am under the impression of having made a mistake when including the "MMO" part into the title. The game will not be all fancy (i.e. 3D or such) on the client side and the logic will completely exist on the server. That is, apart from basic form validation for the user which will also be mirrored on the server side. So the target toolset will be HTML5, JavaScript, probably JQuery(UI). My question is more related to the software architecture/design of a system that enforces certain rules. Separation of ruleset and presentation One problem I am having is that I want to separate the game rules from the presentation. The first step would be to make an own module for the game "engine" that only exposes an interface that allows all actions to be taken in a clean way. If an action fails with regard to some pre/post condition, the engine throws an exception which is then presented to the user like "you cannot sell something you do not own" or "after that you would end up in a situation which is not a valid game state." The problem here is that I would like to be able to not even present invalid action in the first place or grey out the corresponding UI elements. Changing and tweaking the ruleset Another big thing is the ruleset. It will probably evolve over time and most definitely must be tweaked. What's more, it should be possible (to a certain extent) to build a ruleset that fits a specific game round, i.e. choosing different kinds of behaviours in different aspects of the game. This would do something like "we play it with extension A today but we throw out extension B." For me, this screams "Architectural/Design pattern" but I have no idea on who might have published on something like this, not even what to google for.

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• Best way to load application settings

  - by enzom83

  A simple way to keep the settings of a Java application is represented by a text file with ".properties" extension containing the identifier of each setting associated with a specific value (this value may be a number, string, date, etc..). C# uses a similar approach, but the text file must be named "App.config". In both cases, in source code you must initialize a specific class for reading settings: this class has a method that returns the value (as string) associated with the specified setting identifier. // Java example Properties config = new Properties(); config.load(...); String valueStr = config.getProperty("listening-port"); // ... // C# example NameValueCollection setting = ConfigurationManager.AppSettings; string valueStr = setting["listening-port"]; // ... In both cases we should parse strings loaded from the configuration file and assign the ??converted values to the related typed objects (parsing errors could occur during this phase). After the parsing step, we must check that the setting values ??belong to a specific domain of validity: for example, the maximum size of a queue should be a positive value, some values ??may be related (example: min < max), and so on. Suppose that the application should load the settings as soon as it starts: in other words, the first operation performed by the application is to load the settings. Any invalid values for the settings ??must be replaced automatically with default values??: if this happens to a group of related settings, those settings are all set with default values. The easiest way to perform these operations is to create a method that first parses all the settings, then checks the loaded values ??and finally sets any default values??. However maintenance is difficult if you use this approach: as the number of settings increases while developing the application, it becomes increasingly difficult to update the code. In order to solve this problem, I had thought of using the Template Method pattern, as follows. public abstract class Setting { protected abstract bool TryParseValues(); protected abstract bool CheckValues(); public abstract void SetDefaultValues(); /// <summary> /// Template Method /// </summary> public bool TrySetValuesOrDefault() { if (!TryParseValues() || !CheckValues()) { // parsing error or domain error SetDefaultValues(); return false; } return true; } } public class RangeSetting : Setting { private string minStr, maxStr; private byte min, max; public RangeSetting(string minStr, maxStr) { this.minStr = minStr; this.maxStr = maxStr; } protected override bool TryParseValues() { return (byte.TryParse(minStr, out min) && byte.TryParse(maxStr, out max)); } protected override bool CheckValues() { return (0 < min && min < max); } public override void SetDefaultValues() { min = 5; max = 10; } } The problem is that in this way we need to create a new class for each setting, even for a single value. Are there other solutions to this kind of problem? In summary: Easy maintenance: for example, the addition of one or more parameters. Extensibility: a first version of the application could read a single configuration file, but later versions may give the possibility of a multi-user setup (admin sets up a basic configuration, users can set only certain settings, etc..). Object oriented design.

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• Why is 0 false?

  - by Morwenn

  This question may sound dumb, but why does 0 evaluates to false and any other [integer] value to true is most of programming languages? String comparison Since the question seems a little bit too simple, I will explain myself a little bit more: first of all, it may seem evident to any programmer, but why wouldn't there be a programming language - there may actually be, but not any I used - where 0 evaluates to true and all the other [integer] values to false? That one remark may seem random, but I have a few examples where it may have been a good idea. First of all, let's take the example of strings three-way comparison, I will take C's strcmp as example: any programmer trying C as his first language may be tempted to write the following code: if (strcmp(str1, str2)) { // Do something... } Since strcmp returns 0 which evaluates to false when the strings are equal, what the beginning programmer tried to do fails miserably and he generally does not understand why at first. Had 0 evaluated to true instead, this function could have been used in its most simple expression - the one above - when comparing for equality, and the proper checks for -1 and 1 would have been done only when needed. We would have considered the return type as bool (in our minds I mean) most of the time. Moreover, let's introduce a new type, sign, that just takes values -1, 0 and 1. That can be pretty handy. Imagine there is a spaceship operator in C++ and we want it for std::string (well, there already is the compare function, but spaceship operator is more fun). The declaration would currently be the following one: sign operator<=>(const std::string& lhs, const std::string& rhs); Had 0 been evaluated to true, the spaceship operator wouldn't even exist, and we could have declared operator== that way: sign operator==(const std::string& lhs, const std::string& rhs); This operator== would have handled three-way comparison at once, and could still be used to perform the following check while still being able to check which string is lexicographically superior to the other when needed: if (str1 == str2) { // Do something... } Old errors handling We now have exceptions, so this part only applies to the old languages where no such thing exist (C for example). If we look at C's standard library (and POSIX one too), we can see for sure that maaaaany functions return 0 when successful and any integer otherwise. I have sadly seen some people do this kind of things: #define TRUE 0 // ... if (some_function() == TRUE) { // Here, TRUE would mean success... // Do something } If we think about how we think in programming, we often have the following reasoning pattern: Do something Did it work? Yes -> That's ok, one case to handle No -> Why? Many cases to handle If we think about it again, it would have made sense to put the only neutral value, 0, to yes (and that's how C's functions work), while all the other values can be there to solve the many cases of the no. However, in all the programming languages I know (except maybe some experimental esotheric languages), that yes evaluates to false in an if condition, while all the no cases evaluate to true. There are many situations when "it works" represents one case while "it does not work" represents many probable causes. If we think about it that way, having 0 evaluate to true and the rest to false would have made much more sense. Conclusion My conclusion is essentially my original question: why did we design languages where 0 is false and the other values are true, taking in account my few examples above and maybe some more I did not think of? Follow-up: It's nice to see there are many answers with many ideas and as many possible reasons for it to be like that. I love how passionate you seem to be about it. I originaly asked this question out of boredom, but since you seem so passionate, I decided to go a little further and ask about the rationale behind the Boolean choice for 0 and 1 on Math.SE :)

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• WPF MVVM ComboBox SelectedItem or SelectedValue not working

  - by cjibo

  Update After a bit of investigating. What seems to be the issue is that the SelectedValue/SelectedItem is occurring before the Item source is finished loading. If I sit in a break point and weight a few seconds it works as expected. Don't know how I'm going to get around this one. End Update I have an application using in WPF using MVVM with a ComboBox. Below is the ViewModel Example. The issue I'm having is when we leave our page and migrate back the ComboBox is not selecting the current Value that is selected. View Model public class MyViewModel { private MyObject _selectedObject; private Collection<Object2> _objects; private IModel _model; public MyViewModel(IModel model) { _model = model; _objects = _model.GetObjects(); } public Collection<MyObject> Objects { get { return _objects; } private set { _objects = value; } } public MyObject SelectedObject { get { return _selectedObject; } set { _selectedObject = value; } } } For the sake of this example lets say MyObject has two properties (Text and Id). My XAML for the ComboBox looks like this. XAML <ComboBox Name="MyComboBox" Height="23" Width="auto" SelectedItem="{Binding Path=SelectedObject,Mode=TwoWay}" ItemsSource="{Binding Objects}" DisplayMemberPath="Text" SelectedValuePath="Id"> No matter which way I configure this when I come back to the page and the object is reassembled the ComboBox will not select the value. The object is returning the correct object via the get in the property though. I'm not sure if this is just an issue with the way the ComboBox and MVVM pattern works. The text box binding we are doing works correctly.

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• Silverlight nested RadGridView SelectedItem DataContext

  - by Ciaran

  Hi, I'm developing a Silverlight 4 app and am using the 2010 Q1 release 1 RadGridView. I'm developing this app using the MVVM pattern and trying to keep my codebehind to a minimum. On my View I have a RadGridView and this binds to a property on my ViewModel. I am setting a property via the SelectedItem. I have a nested RadGridView and I want to set a property on my ViewModel to the SelectedItem but I cannot. I think the DataContext of my nested grid is the element in the parent's bound collection, rather than my ViewModel. I can easily use codebehind to set my ViewModel property from the SelectionChanged event on the nested grid, but I'd rather not do this. I have tried to use my viewModelName in the ElementName in my nested grid to specify that for SelectedItem, the ViewModel is the DataContext, but I cannot get this to work. Any ideas? Here is my Xaml: <grid:RadGridView x:Name="master" ItemsSource="{Binding EntityClassList, Mode=TwoWay}" SelectedItem="{Binding SelectedEntityClass, Mode=TwoWay}" AutoGenerateColumns="False" > <grid:RadGridView.Columns> <grid:GridViewSelectColumn></grid:GridViewSelectColumn> <grid:GridViewDataColumn DataMemberBinding="{Binding Description}" Header="Description"/. </grid:RadGridView.Columns> <grid:RadGridView.RowDetailsTemplate> <DataTemplate> <grid:RadGridView x:Name="child" ItemsSource="{Binding EntityDetails, Mode=TwoWay}" SelectedItem="{Binding DataContext.SelectedEntityDetail, ElementName='RequestView', Mode=TwoWay}" AutoGenerateColumns="False" > <grid:RadGridView.Columns> <grid:GridViewSelectColumn></grid:GridViewSelectColumn> <grid:GridViewDataColumn DataMemberBinding="{Binding ServiceItem}" Header="Service Item" /> <grid:GridViewDataColumn DataMemberBinding="{Binding Comment}" Header="Comments" /> </grid:RadGridView.Columns> </grid:RadGridView> </DataTemplate> </grid:RadGridView.RowDetailsTemplate> </grid:RadGridView>

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• Why LINQ to Entities won't let me initialize just some properties of an Entity?

  - by emzero

  So I've started to add Entity Framework 4 into a legacy web application (ASP.NET WebForms). As a start I have auto-generated some entities from the database. Also I want to apply Repository Pattern. There is an entity called Visitor and its repository VisitorRepository In VisitorRepository I have the following method: public IEnumerable<Visitor> GetActiveVisitors() { var visitors = from v in _context.Visitors where v.IsActive select new Visitor { VisitorID = v.VisitorID, EmailAddress = v.EmailAddress, RegisterDate = v.RegisterDate, Company = v.Company, Position = v.Position, FirstName = v.FirstName, LastName = v.LastName }; return visitors.ToList(); } That List is then bound to a repeater and when trying to do <%# Eval('EmailAddress') #%> it throws the following exception. The entity or complex type 'Model.Visitor' cannot be constructed in a LINQ to Entities query. A) Why is this happening? How I can workaround this? Do I need to select an anonymous type and then use that to initialize my entities??? B) Why every example I've seen makes use of 'select new' (anonymous object) instead of initializing a known type? Anonymous types are useless unless you are retrieving the data and showing it in the same layer. As far as I know anonymous types cannot be returned from methods? So what's the real point of them??? Thank you all

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• MVC2 DataAnnotations on ViewModel - ModelState.isValid Always Returns true

  - by ScottSEA

  I have an MVC2 Application that uses MVVM pattern. I am trying use Data Annotations to validate form input. In my ThingsController I have two methods: [HttpGet] public ActionResult Index() { return View(); } public ActionResult Details(ThingsViewModel tvm) { if (!ModelState.IsValid) return View(tvm); try { Query q = new Query(tvm.Query); ThingRepository repository = new ThingRepository(q); tvm.Airplanes = repository.All(); return View(tvm); } catch (Exception) { return View(); } } My Details.aspx view is strongly typed to the ThingsViewModel: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<Config.Web.Models.ThingsViewModel>" %> The ViewModel is a class consisting of a IList of returned Thing objects and the Query string (which is submitted on the form) and has the Required data annotation: public class ThingsViewModel { public IList<Thing> Things{ get; set; } [Required(ErrorMessage="You must enter a query")] public string Query { get; set; } } When I run this, and click the submit button on the form without entering a value I get a YSOD with the following error: The model item passed into the dictionary is of type 'Config.Web.Models.ThingsViewModel', but this dictionary requires a model item of type System.Collections.Generic.IEnumerable`1[Config.Domain.Entities.Thing]'. How can I get Data Annotations to work with a ViewModel? I cannot see what I'm missing or where I'm going wrong - the VM was working just fine before I started mucking around with validation.

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• NServiceBus and NHibernate - Message Handler and Transactions

  - by mattcodes

  From my understanding NServiceBus executes the Handle method of an IMessageHandler within a transaction, if an exception propagates out of this method, then NServiceBus will ensure the message is put back on the message queue (up X amount of times before error queue) etc.. so we have an atomic operation so to speak. Now when if I inside my NServiceBus Message Handle method I do something like this using(var trans = session.BeginTransaction()) { person.Age = 10; session.Update<Person>(person); trans.Commit() } using(var trans2 = session.BeginTransaction()) { person.Age = 20; session.Update<Person>(person); // throw new ApplicationException("Oh no"); trans2.Commit() } What is the effect of this on the transaction scope? Is trans1 now counted as a nested transaction in terms of its relationship with the Nservicebus transaction even though we have done nothing to marry them up? (if not how would one link onto the transaction of NServiceBus? Looking at the second block (trans2), if I uncomment the throw statement, will the NServiceBus transaction then rollback trans1 as well? In basic scenarios, say I dump the above into a console app, then trans1 is independent, commit, flushed and won't rollback. I'm trying to clarify what happens now we sit in someone else's transaction like NServiceBus? The above is just example code, im wouldnt be working directly with session, more like through a uow pattern.

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• Silverlight data binding to parent user control's properties with using MVVM in both controls

  - by MagicMax

  Hello! I have two UserControls ("UserControlParentView" and "UserControlChildView") with MVVM pattern implemented in both controls. Parent control is a container for Child control and child control's property should be updated by data binding from Parent control in order to show/hide some check box inside Child control. Parent Control Description UserControlParentViewModel has property: private bool isShowCheckbox = false; public bool IsShowCheckbox { get { return isShowCheckbox; } set { isShowCheckbox = value; NotifyPropertyChanged("IsShowCheckbox"); } } UserControlParentViewModel - how I set DataContext of Parent control: public UserControlParentView() { InitializeComponent(); this.DataContext = new UserControlParentViewModel(); } UserControlParentView contains toggle button (in XAML), bound to UserControlParentViewModel's property IsShowCheckbox <ToggleButton Grid.Column="1" IsChecked="{Binding IsShowCheckbox, Mode=TwoWay}"></ToggleButton> Also Parent control contains instance of child element (somewhere in XAML) <local:UserControlChildView IsCheckBoxVisible="{Binding IsShowCheckbox}" ></local:UserControlChildView> so property in child control should be updated when user togggle/untoggle button. Child control contains Boolean property to be updated from parent control, but nothing happened! Breakpoint never fired! Property in UserControlChildView that should be updated from Parent control (here I plan to make chechBox visible/hidden in code behind): public bool IsCheckBoxVisible { get { return (bool)GetValue(IsCheckBoxVisibleProperty); } set { SetValue(IsCheckBoxVisibleProperty, value); } } // Using a DependencyProperty as the backing store for IsCheckBoxVisible. This enables animation, styling, binding, etc... public static readonly DependencyProperty IsCheckBoxVisibleProperty = DependencyProperty.Register("IsCheckBoxVisible", typeof(bool), typeof(TopMenuButton), new PropertyMetadata(false)); So the question is - what I'm doing wrong? Why child's property is never updated? BTW - there is no any binding error warnings in Output window...

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• Implementing the double-click event on Silverlight 4 Datagrid

  - by Mohammed Mudassir Azeemi

  Any good soul have an example of implementing the "Command Pattern" introduced by Prism on "Double-click event" of Silverlight 4.0 DataGrid. I did try the following: <data:DataGrid x:Name="dgUserRoles" AutoGenerateColumns="False" Margin="0" Grid.Row="0" ItemsSource="{Binding Path=SelectedUser.UserRoles}" IsReadOnly="False" > <data:DataGrid.Columns> <data:DataGridTemplateColumn Header=" "> <data:DataGridTemplateColumn.CellTemplate> <DataTemplate> <Button Width="20" Height="20" Click="Button_Click" Command="{Binding EditRoleClickedCommand}" CommandParameter="{Binding SelectedRole}" > </Button> </DataTemplate> </data:DataGridTemplateColumn.CellTemplate> </data:DataGridTemplateColumn> <data:DataGridTextColumn Header="Role Name" Binding="{Binding RoleName}" /> <data:DataGridTextColumn Header="Role Code" Binding="{Binding UserroleCode}" IsReadOnly="True"/> <data:DataGridCheckBoxColumn Header="UDFM Managed" Binding="{Binding RoleIsManaged}" IsReadOnly="True" /> <data:DataGridCheckBoxColumn Header="UDFM Role Assigned" Binding="{Binding UserroleIsUdfmRoleAssignment}" IsReadOnly="True" /> <data:DataGridTextColumn Header="Source User" Binding="{Binding SourceUser}" IsReadOnly="True" /> </data:DataGrid.Columns> </data:DataGrid> As you see I did try to hook up the Command there and it is not firing the event in my View Model. Looking for a good alternative.

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• Pass data to Child Window in Silverlight 4 using MVVM

  - by Archie

  Hello, I have a datagrid with master detail implementation as follows: <data:DataGrid x:Name="dgData" Width="600" ItemsSource="{Binding Path=ItemCollection}" HorizontalScrollBarVisibility="Hidden" CanUserSortColumns="False" RowDetailsVisibilityChanged="dgData_RowDetailsVisibilityChanged"> <data:DataGrid.Columns> <data:DataGridTextColumn Header="Item" Width="*" Binding="{Binding Item,Mode=TwoWay}"/> <data:DataGridTextColumn Header="Company" Width="*" Binding="{Binding Company,Mode=TwoWay}"/> </data:DataGrid.Columns> <data:DataGrid.RowDetailsTemplate> <DataTemplate> <data:DataGrid x:Name="dgrdRowDetail" Width="400" AutoGenerateColumns="False" HorizontalAlignment="Center" HorizontalScrollBarVisibility="Hidden" Grid.Row="1"> <data:DataGrid.Columns> <data:DataGridTextColumn Header="Date" Width="*" Binding="{Binding Date,Mode=TwoWay}"/> <data:DataGridTextColumn Header="Price" Width="*" Binding="{Binding Price, Mode=TwoWay}"/> <data:DataGridTemplateColumn> <data:DataGridTemplateColumn.CellTemplate> <DataTemplate> <Button Content="Show More Details" Click="buttonShowDetail_Click"></Button> </DataTemplate> </data:DataGridTemplateColumn.CellTemplate> </data:DataGridTemplateColumn> </data:DataGrid.Columns> </data:DataGrid> </DataTemplate> </data:DataGrid.RowDetailsTemplate> </data:DataGrid> I want to open a Child window in clicking the button which shows more details about the product. I'm using MVVM pattern. My Model contains a method which takes the Item name as input and retursn the Details data. My problem is how should I pass the Item to ViewModel which will get the Details data from Model? and where shoukd I open the new Child Window? In View or ViewModel? Please help.Thanks.

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• log file is not getting created using JDK logging with Commons-logging

  - by Saida Dhanavath

  When I run the TestJcLLoggingService class log messages are coming to Console but no log file is created, please help me if you know the answer. two source files are pasted below. TestJcLLoggingService.java package com.amadeus.psp.pasd.logging; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.stereotype.Service; @Service public class TestJCLLoggingService { private static Log psp_log = LogFactory.getLog(TestJCLLoggingService.class); public static String testJCLLoggingServiceMethod(){ psp_log.info("start of method testJCLLoggingServiceMethod class TestJCLLoggingService"); psp_log.info("start of method testJCLLoggingServiceMethod class TestJCLLoggingService"); return "This is a test string for JCLLogging"; } public static void main(String[] args){ testJCLLoggingServiceMethod(); } } logging.properties handlers = java.util.logging.ConsoleHandler, java.util.logging.FileHandler .level = ALL com.amadeus.psp.pasd.level=ALL java.util.logging.ConsoleHandler.level = ALL java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter java.util.logging.FileHandler.pattern = %h/java%u.log java.util.logging.FileHandler.level=ALL java.util.logging.FileHandler.limit=50000 java.util.logging.FileHandler.count=1 java.util.logging.FileHandler.formatter=java.util.logging.SimpleFormatter java.util.logging.FileHandler.append=true Thanks in advance.

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• Silverlight 4 with WCF RIA architecture applying DDD

  - by doteneter

  Hello, In my ASP.NET MVC applications I use DDD and it works very well. I'm new to Silverlight development and would like to know how could I apply DDD to build a new architecture. I had a look on WCF RIA Services and what is exposed by default it's the simple CRUD methods. I would like to use MVVM pattern. I thought about general architecture and don't know if what I'm thinking about make sense in Silverlight development. I thought about creating Domain Model on the top of SVC. I would than expose by WCF RIA some operation that deals with aggreates in my Domain Model instead of simple CRUD. What I would aloso expose is the ViewModel entieties that could be used by the view. I don't know if it's make sense, if I'm going in a good direction or if applying DDD in Silverlight 4 development is a good practice. I didn't find much informations on Internet. I'll appreciate if you could point me to some interesting links or if you can give me some hints. Thanks for your help.

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• Exception from HRESULT: 0x80020009 (DISP_E_EXCEPTION)) in SharePoint

  - by BeraCim

  Hi all: After googling for many hours for a solution for the above Sharepoint exception, I have come to SO for help on this one... I believe the cause of me getting the above exception is because of the following code: try { using (SPSite site = new SPSite(siteId, spUserToken)) { using (SPWeb web = site.OpenWeb(webId)) { createNewSite(web); } } } createNewSite(web) changes the name and URL of "web" using AllowUnsafeUpdates, so when it comes out of the method it has been changed. My few months worth of Sharepoint developing experience suggest that that is the cause of the exception. "web" is no longer used anymore so I can comfortably null it myself. The problem here is... it didnt work: try { using (SPSite site = new SPSite(siteId, spUserToken)) { SPWeb web = null; using (web = site.OpenWeb(webId)) { createNewSite(web); if (web != null) { web = null; } } } } I believe that the original developer used the using declaration to avoid SPWeb objects from leaking. Asides that I think it is okay for me to break this pattern solely for the purpose of getting rid of that dreaded exception. So the question: what can I do to the above code to potentially fix this exception? Thanks.

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• Applying Test Driven Development to a tightly coupled architecture

  - by Chris D

  Hi all, I've recently been studying TDD, attended a conference and have dabbled in few tests and already I'm 100% sold, I absolutely love it TDD. As a result I've raised this with my seniors and they are prepared to give it a chance, so they have tasked me with coming up with a way to implement TDD in the development of our enterprise product. The problem is our system has evolved since the days of VB6 to .NET and implements alot of legacy technology and some far from best practice development techniques i.e. alot of business logic in the ASP.NET code behind and client script. The largest problem however is how our classes are tightly coupled with database access; properties, methods, constructors - usually has some database access in some form or another. We use an in-house data access code generator tool that creates sqlDataAdapters that gives us all the database access we could ever want, which helps us develop extremely quickly, however, classes in our business layer are very tightly coupled to this data layer - we aren't even close to implementing some form of repository design. This and the issues above have created me all sorts of problems. I have tried to develop some unit tests for some existing classes I've already written but the tests take ALOT longer to run since db access is required, not to mention since we use the MS Enterprise Caching framework I am forced to fake a httpcontext for my tests to run successfully which isn't practical. Also, I can't see how to use TDD to drive the design of any new classes I write since they have to be soo tightly coupled to the database ... help! Because of the architecture of the system it appears I can't implement TDD without some real hack which in my eyes just defeats the aim of TDD and the huge benefits that come with. Does anyone have any suggestions how I could implement TDD with the constraints I'm bound too? or do I need to push the repository design pattern down my seniors throats and tell them we either change our architecture/development methodology or forget about TDD altogether? :) Thanks

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• How create a Firefox-like search textbox in WPF?

  - by Simon

  Hey there. I'm writing an application in WPF using the MVVM-pattern and will really often use TextBoxes. I don't want to use labels for the user to know user what the text box is for, i.e. I don't want something like this: <TextBlock> Name: </TextBlock> <TextBox /> Instead, I would like the TextBox to contain its own label. Statically, you would express it like this: <TextBox>Name</TextBox> If the cursor is displayed in the textbox, i.e. the TextBox gains focus, I want the description text to disappear. If the TextBox is left empty and it loses the focus, the description text should be shown again. It's similar to the search textbox of StackOverflow or the one of Firefox. (please tell me if your not sure what I mean). One TextBox's label may change at runtime, dependending on e.g. a ComboBox's selected element or a value in my ViewModel. (It's like in Firefox's search TextBox, if you select google from the search engins' menu, the TextBox's label changes to "Google", if you select "Yahoo" its set to "Yahoo"). Thus I want to be able to bind the label's content. Consider that I may already have a Binding on the Text-Property of the TextBox. How can implement such a behaviour and make it reusable for any of my TextBox's? Code is welcome but not needed; a description of what to do is enough. Thank you in advance.

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• Writing a Javascript library that is code-completion and code-inspection friendly

  - by Vivin Paliath

  I recently made my own Javascript library and I initially used the following pattern: var myLibrary = (function () { var someProp = "..."; function someFunc() { ... } function someFunc2() { ... } return { func: someFunc, fun2: someFunc2, prop: someProp; } }()); The problem with this is that I can't really use code completion because the IDE doesn't know about the properties that the function literal is returning (I'm using IntelliJ IDEA 9 by the way). I've looked at jQuery code and tried to do this: (function(window, undefined) { var myLibrary = (function () { var someProp = "..."; function someFunc() { ... } function someFunc2() { ... } return { func: someFunc, fun2: someFunc2, prop: someProp; } }()); window.myLibrary = myLibrary; }(window)); I tried this, but now I have a different problem. The IDE doesn't really pick up on myLibrary either. The way I'm solving the problem now is this way: var myLibrary = { func: function() { }, func2: function() { }, prop: "" }; myLibrary = (function () { var someProp = "..."; function someFunc() { ... } function someFunc2() { ... } return { func: someFunc, fun2: someFunc2, prop: someProp; } }()); But that seems kinda clunky, and I can't exactly figure out how jQuery is doing it. Another question I have is how to handle functions with arbitrary numbers of parameters. For example, jQuery.bind can take 2 or 3 parameters, and the IDE doesn't seem to complain. I tried to do the same thing with my library, where a function could take 0 arguments or 1 argument. However, the IDE complains and warns that the correct number of parameters aren't being sent in. How do I handle this?

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