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  • Inside the DLR – Invoking methods

    - by Simon Cooper
    So, we’ve looked at how a dynamic call is represented in a compiled assembly, and how the dynamic lookup is performed at runtime. The last piece of the puzzle is how the resolved method gets invoked, and that is the subject of this post. Invoking methods As discussed in my previous posts, doing a full lookup and bind at runtime each and every single time the callsite gets invoked would be far too slow to be usable. The results obtained from the callsite binder must to be cached, along with a series of conditions to determine whether the cached result can be reused. So, firstly, how are the conditions represented? These conditions can be anything; they are determined entirely by the semantics of the language the binder is representing. The binder has to be able to return arbitary code that is then executed to determine whether the conditions apply or not. Fortunately, .NET 4 has a neat way of representing arbitary code that can be easily combined with other code – expression trees. All the callsite binder has to return is an expression (called a ‘restriction’) that evaluates to a boolean, returning true when the restriction passes (indicating the corresponding method invocation can be used) and false when it does’t. If the bind result is also represented in an expression tree, these can be combined easily like so: if ([restriction is true]) { [invoke cached method] } Take my example from my previous post: public class ClassA { public static void TestDynamic() { CallDynamic(new ClassA(), 10); CallDynamic(new ClassA(), "foo"); } public static void CallDynamic(dynamic d, object o) { d.Method(o); } public void Method(int i) {} public void Method(string s) {} } When the Method(int) method is first bound, along with an expression representing the result of the bind lookup, the C# binder will return the restrictions under which that bind can be reused. In this case, it can be reused if the types of the parameters are the same: if (thisArg.GetType() == typeof(ClassA) && arg1.GetType() == typeof(int)) { thisClassA.Method(i); } Caching callsite results So, now, it’s up to the callsite to link these expressions returned from the binder together in such a way that it can determine which one from the many it has cached it should use. This caching logic is all located in the System.Dynamic.UpdateDelegates class. It’ll help if you’ve got this type open in a decompiler to have a look yourself. For each callsite, there are 3 layers of caching involved: The last method invoked on the callsite. All methods that have ever been invoked on the callsite. All methods that have ever been invoked on any callsite of the same type. We’ll cover each of these layers in order Level 1 cache: the last method called on the callsite When a CallSite<T> object is first instantiated, the Target delegate field (containing the delegate that is called when the callsite is invoked) is set to one of the UpdateAndExecute generic methods in UpdateDelegates, corresponding to the number of parameters to the callsite, and the existance of any return value. These methods contain most of the caching, invoke, and binding logic for the callsite. The first time this method is invoked, the UpdateAndExecute method finds there aren’t any entries in the caches to reuse, and invokes the binder to resolve a new method. Once the callsite has the result from the binder, along with any restrictions, it stitches some extra expressions in, and replaces the Target field in the callsite with a compiled expression tree similar to this (in this example I’m assuming there’s no return value): if ([restriction is true]) { [invoke cached method] return; } if (callSite._match) { _match = false; return; } else { UpdateAndExecute(callSite, arg0, arg1, ...); } Woah. What’s going on here? Well, this resulting expression tree is actually the first level of caching. The Target field in the callsite, which contains the delegate to call when the callsite is invoked, is set to the above code compiled from the expression tree into IL, and then into native code by the JIT. This code checks whether the restrictions of the last method that was invoked on the callsite (the ‘primary’ method) match, and if so, executes that method straight away. This means that, the next time the callsite is invoked, the first code that executes is the restriction check, executing as native code! This makes this restriction check on the primary cached delegate very fast. But what if the restrictions don’t match? In that case, the second part of the stitched expression tree is executed. What this section should be doing is calling back into the UpdateAndExecute method again to resolve a new method. But it’s slightly more complicated than that. To understand why, we need to understand the second and third level caches. Level 2 cache: all methods that have ever been invoked on the callsite When a binder has returned the result of a lookup, as well as updating the Target field with a compiled expression tree, stitched together as above, the callsite puts the same compiled expression tree in an internal list of delegates, called the rules list. This list acts as the level 2 cache. Why use the same delegate? Stitching together expression trees is an expensive operation. You don’t want to do it every time the callsite is invoked. Ideally, you would create one expression tree from the binder’s result, compile it, and then use the resulting delegate everywhere in the callsite. But, if the same delegate is used to invoke the callsite in the first place, and in the caches, that means each delegate needs two modes of operation. An ‘invoke’ mode, for when the delegate is set as the value of the Target field, and a ‘match’ mode, used when UpdateAndExecute is searching for a method in the callsite’s cache. Only in the invoke mode would the delegate call back into UpdateAndExecute. In match mode, it would simply return without doing anything. This mode is controlled by the _match field in CallSite<T>. The first time the callsite is invoked, _match is false, and so the Target delegate is called in invoke mode. Then, if the initial restriction check fails, the Target delegate calls back into UpdateAndExecute. This method sets _match to true, then calls all the cached delegates in the rules list in match mode to try and find one that passes its restrictions, and invokes it. However, there needs to be some way for each cached delegate to inform UpdateAndExecute whether it passed its restrictions or not. To do this, as you can see above, it simply re-uses _match, and sets it to false if it did not pass the restrictions. This allows the code within each UpdateAndExecute method to check for cache matches like so: foreach (T cachedDelegate in Rules) { callSite._match = true; cachedDelegate(); // sets _match to false if restrictions do not pass if (callSite._match) { // passed restrictions, and the cached method was invoked // set this delegate as the primary target to invoke next time callSite.Target = cachedDelegate; return; } // no luck, try the next one... } Level 3 cache: all methods that have ever been invoked on any callsite with the same signature The reason for this cache should be clear – if a method has been invoked through a callsite in one place, then it is likely to be invoked on other callsites in the codebase with the same signature. Rather than living in the callsite, the ‘global’ cache for callsite delegates lives in the CallSiteBinder class, in the Cache field. This is a dictionary, typed on the callsite delegate signature, providing a RuleCache<T> instance for each delegate signature. This is accessed in the same way as the level 2 callsite cache, by the UpdateAndExecute methods. When a method is matched in the global cache, it is copied into the callsite and Target cache before being executed. Putting it all together So, how does this all fit together? Like so (I’ve omitted some implementation & performance details): That, in essence, is how the DLR performs its dynamic calls nearly as fast as statically compiled IL code. Extensive use of expression trees, compiled to IL and then into native code. Multiple levels of caching, the first of which executes immediately when the dynamic callsite is invoked. And a clever re-use of compiled expression trees that can be used in completely different contexts without being recompiled. All in all, a very fast and very clever reflection caching mechanism.

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  • How do I make money from my FOSS while staying anonymous?

    - by user21007
    Let's say that: You have created a FOSS project that other people find useful, perhaps useful enough to donate to or pay for modifications to be done. It is a perfectly legitimate and innocuous software project. It has nothing to do with cryptography as munitions, p2p music, or anything likely to lead to a search warrant or being sued. You want your involvement to stay anonymous or pseudonymous. You would like to receive some money for your efforts, if people are willing. Is that possible, and if so, how could it be done? When I talk about anonymity, I realize that it is necessary to define the extent. I am not talking about Wikileaks style 20 layers of proxies worth of anonymity. I would expect a 3 letter agency to be able to identify the person easily. What is wanted is shielding from commercial competitors or random people, who would not be expected to be able to get the financial intermediary to divulge your details just by asking for them. Why would you want to stay anonymous? I can think of several valid reasons, maybe you operate a stealth mode startup and don't want to give your competitors clues as to the technology you are using. Maybe it is a project that has nothing to do with your daily job, is not developed there, but the company you work for has an unfair (and possibly unenforceable) policy stating that any coding you do is owned by them. Maybe you just value your privacy. For what it's worth, you intend to pay the relevant taxes in your country on any donations.

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  • How do you KISS?

    - by Conor
    The KISS principle is a highly quoted design mantra. The aim of this principle is to stamp out unnecessary complexity on a project. This is a good thing, saving time, energy and money. It can lead to a relatively stress free implementation and a simple, elegant, maintainable end product. A lot of discussion on KISS provides mechanisms to simplify requirements, design and implementation. Things that spring to mind include: avoid scope creep; simple obvious design and code; minimal run-time dependencies; refactoring to maintain simplicity; etc. However there are a lot of implicit things that we do to KISS. Examples: small team sizes; minimal management layers; tidy desk; mastery of a single IDE; clear concise error messages; scripts to automate/encapsulate tasks; etc Why KISS practices do you apply? How have they been of benefit? I'm especially interested in non-obvious practices.

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  • Where to implement storable items

    - by James Hay
    I'm creating a multiplayer online trading game. The things that are traded range from raw items to complex products. For example Steel is a raw item. Mechanical Assembly is a more complex item that requires 2x Steel and maybe 1x Rubber. Then Hydraulics is an item that contains 2x Mechanical Assemblies and 1x Electronics (which is another complex item). So and so forth. These items will be created by me, players can't create their own items, so it doesn't need to be able to handle arbitrary layers of complexity for items. If my example isn't clear, think Minecraft. You have wooden planks, which can be made into sticks. From there the sticks - combined with metals - can be made into tools. My game is nothing to do with minecraft or any sandbox building game, but it uses a similar progressive complexity to creating items that I want to have in my game. My question is basically, how do you store something like this assuming that I will want to add more items in the future? Do you store it in a database or in a seperate library that the game uses? EDIT None of the items actually "do" anything, they are simply there to either sell, purchase, or combine with other items to make a more complex item, which can then be sold, purchased or combined... you get the idea. The items themselves would not have any properties, but the instances of the items would. For example an item that one player has would have a certain "quality" and if they were selling it a certain "price". An instance of that same item that a different player had would need to have a different "quality" and "price" if they were selling it. I think the price part will not be required on an individual item because instead I would have a "sale" object which was for a price and contained certain items.

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  • XPath & XML EDI B2B

    - by PearlFactory
    GoodToGo :) Best XML Editor is Altova XMLSpy 2011 http://www.torrenthound.com/hash/bfdbf55baa4ca6f8e93464c9a42cbd66450bb950/torrent-info/Altova-XMLSpy-Enterprise-Edition-SP1-2011-v13-0-1-0-h33t-com-Full For whatever reason Piratebay has trojans and other nasties..Search in torrent.eu for Altova XMLSpy Enterprise Edition SP1 2011 v13.0.1.0 Also if you like the product purchase it in a Commercial Enviroment Any well structured/complex XML can be parsed @ the speed of light using XPATH querys and not the C# objects XPathNodeIterator and others etc ....Never do loops  or Genirics or whatever highlevel language technology. Use the power of XPATH i.e Will use a Simple (Do while) as an example. We could have many different techs all achieveing the same result Instead of   xmlNI2 = xmlNav.Select("/p:BookShop")         if (xmlNI2.Count != 0)            {                                 while ((xmlNI2.MoveNext()))              string aNode =xmlNI2.SelectSingleNode('Book', nsmgr); if (aNode =="The Book I am after")       Console.WriteLine("Found My Book);   This lengthy cumbersome task can be achieved with a simple XPATH query Console.WriteLine((xmlNavg.SelectSingleNode("/p:BookShop/Book[.='The Book I am aFter ']", nsmgr)).Value.ToString()); Use the power of the parser and eliminate the middleman C#/MSIL/JIT etc etc Get Started Fast and use the parser as Outlined 1) Open XML and goto Grid Mode 2) Select XPATH tab on the bottom viewer/window as shown  From here you get intellisense and can quickly learn how to navigate/find the data using XPATH A key component to Navigation with XPATH is to use the "../ " command . This basically says from where I am now go up 1 level . With Xpath all commands are cumalative. i.e you can search for a book title @ the 2nd level of the XML and from there traverse 15 layers to paragraphs or words on a page with expression validation occuring throughout this process etc  (So in essence you may have arrived @ a node within the XML and have met 15 conditions along the way ) Given 1-2 days with XmlSpy and XPATH you unlock a technology that is super fast and simple to use. XML is a core component to what lays under the hood of so many techs. So it is no wonder that you want to be able to goto  the atomic level to achieve the result you want Justin P.S For a long time I saw XML as slow and a bit boring but now converted

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  • ORAchk version 2.2.5 is now available for download

    - by Gerry Haskins
    Those awfully nice ORAchk folks have asked me to let you know about their latest release... ORAchk version 2.2.5 is now available for download, new features in 2.2.5: Running checks for multiple databases in parallel Ability to schedule multiple automated runs via ORAchk daemon New "scratch area" for ORAchk temporary files moved from /tmp to a configurable $HOME directory location System health score calculation now ignores skipped checks Checks the health of pluggable databases using OS authentication New report section to report top 10 time consuming checks to be used for optimizing runtime in the future More readable report output for clusterwide checks Includes over 50 new Health Checks for the Oracle Stack Provides a single dashboard to view collections across your entire enterprise using the Collection Manager, now pre-bundled Expands coverage of pre and post upgrade checks to include standalone databases, with new profile options to run only these checks Expands to additional product areas in E-Business Suite of Workflow & Oracle Purchasing and in Enterprise Manager Cloud Control ORAchk has replaced the popular RACcheck tool, extending the coverage based on prioritization of top issues reported by users, to proactively scan for known problems within the area of: Oracle Database Standalone Database Grid Infrastructure & RAC Maximum Availability Architecture (MAA) Validation Upgrade Readiness Validation Golden Gate Enterprise Manager Cloud Control Repository E-Business Suite Oracle Payables (R12 only) Oracle Workflow Oracle Purchasing (R12 only) Oracle Sun Systems Oracle Solaris ORAchk features: Proactively scans for the most impactful problems across the various layers of your stack Streamlines how to investigate and analyze which known issues present a risk to you Executes lightweight checks in your environment, providing immediate results with no configuration data sent to Oracle Local reporting capability showing specific problems and their resolutions Ability to configure email notifications when problems are detected Provides a single dashboard to view collections across your entire enterprise using the Collection Manager ORAchk will expand in the future with high impact checks in existing and additional product areas. If you have particular checks or product areas you would like to see covered, please post suggestions in the ORAchk subspace in My Oracle Support Community. For more details about ORAchk see Document 1268927.2

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  • Clean MVC design when there is viewer latency

    - by Tony Suffolk 66
    It isn't clear if this question has already been answered, so apologies in advance if this is a duplicate : I am implementing a game and trying to design around a clean MVC pattern - so my Control plane will implement the rules of the game (but not how the game is displayed), and the View plane implements how the game is displayed, and user iteraction - i.e. what game items or controls the user has activated. The challenge that I have is this : In my game the Control Plane can move game items more or less instaneously (The decision about what item to place where - and some of the initial consequences of that placement are reasonably trivial to calculate), but I want to design the Control Plane so that the View plane can display these movements either instaneously or using movement animations. The other complication is that player interaction must be locked out while those game items are moving (similar to chess - you can't attack an opposing piece as it moves past one of your pieces) So do I : Implement all the logic in the Control Plane asynchronously - and separate the descision making from the actions - so the Control plane decides piece 'A' needs to move to a given place - tells the view plane, and but does not implement the move in data until the view plane informs the control plane that the move/animation is complete. A lot of interlock points between the two layers. Implement all the control plane logic in one place - decisions and movement (keeping track of what moved where), and pass all the movements in one go to the View plane to do with what it will. Control Plane is almost fire and forget here. A hybrid of 1 & 2 - The control plane implements all the moves in a temporary data store - but maintains a second store which reflects what is actually visible to the viewer, based on calls and feedback from the View plane. All 3 are relatively easy to implement (target language is python), but having never done a clean MVC pattern with view latency before - I am not sure which design is best

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  • Need advice on framework design: how to make extending easy

    - by beginner_
    I'm creating a framework/library for a rather specific use-case (data type). It uses diverse spring components, including spring-data. The library has a set of entity classes properly set up and according service and dao layers. The main work or main benefit of the framework lies in the dao and service layer. Developers using the framework should be able to extend my entity classes to add additional fields they require. Therefore I made dao and service layer generic so it can be used by such extended entity classes. I now face an issue in the IO part of the framework. It must be able to import the according "special data type" into the database. In this part I need to create a new entity instance and hence need the actual class used. My current solution is to configure in spring a bean of the actual class used. The problem with this is that an application using the framework could only use 1 implementation of the entity (the original one from me or exactly 1 subclass but not 2 different classes of the same hierarchy. I'm looking for suggestions / desgins for solving this issue. Any ideas?

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  • Dojo and Separate JavaScript File

    - by Bunch
    For a project I needed to use the ArcGIS API for some mapping. To use this you need to use Dojo but in this case all it really comes down to is adding some require lines and a addOnLoad on your web page. At first everything was working great, the maps rendered and the various layers would populate as needed. Once it was working I started moving the various javascript functions into their own files to keep everything nice and neat. Then the problems started, mainly the map would not show up any more. So that was a pretty big problem. Luckily the fix was pretty simple, just move the dojo.addOnLoad line into it’s own script tag. If I had the dojo.addOnLoad in the same script block as the various require lines it would not work as expected. Works: <script type="text/javascript" language="javascript" src="javascript/test.js" />     <script type="text/javascript">       dojo.require("esri.map");       dojo.require("esri.tasks.locator");       dojo.require("esri.tasks.query");       dojo.require("esri.tasks.geometry");  </script>  <script type="text/javascript">      dojo.addOnLoad(init);  </script> Does not work: <script type="text/javascript" language="javascript" src="javascript/test.js" /> <script type="text/javascript">       dojo.require("esri.map");       dojo.require("esri.tasks.locator");       dojo.require("esri.tasks.query");       dojo.require("esri.tasks.geometry");       dojo.addOnLoad(init); </script> Technorati Tags: JavaScript,Dojo

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  • Navigation in Win8 Metro Style applications

    - by Dennis Vroegop
    In Windows 8, Touch is, as they say, a first class citizen. Now, to be honest: they also said that in Windows 7. However in Win8 this is actually true. Applications are meant to be used by touch. Yes, you can still use mouse, keyboard and pen and your apps should take that into account but touch is where you should focus on initially. Will all users have touch enabled devices? No, not in the first place. I don’t think touchscreens will be on every device sold next year. But in 5 years? Who knows? Don’t forget: if your app is successful it will be around for a long time and by that time touchscreens will be everywhere. Another reason to embrace touch is that it’s easier to develop a touch-oriented app and then to make sure that keyboard, nouse and pen work as doing it the other way around. Porting a mouse-based application to a touch based application almost never works. The reverse gives you much more chances for success. That being said, there are some things that you need to think about. Most people have more than one finger, while most users only use one mouse at the time. Still, most touch-developers translate their mouse-knowledge to the touch and think they did a good job. Martin Tirion from Microsoft said that since Touch is a new language people face the same challenges they do when learning a new real spoken language. The first thing people try when learning a new language is simply replace the words in their native language to the newly learned words. At first they don’t care about grammar. To a native speaker of that other language this sounds all wrong but they still will be able to understand what the intention was. If you don’t believe me: try Google translate to translate something for you from your language to another and then back and see what happens. The same thing happens with Touch. Most developers translate a mouse-click into a tap-event and think they’re done. Well matey, you’re not done. Not by far. There are things you can do with a mouse that you cannot do with touch. Think hover. A mouse has the ability to ‘slide’ over UI elements. Touch doesn’t (I know: with Pen you can do this but I’m talking about actual fingers here). A touch is either there or it isn’t. And right-click? Forget about it. A click is a click.  Yes, you have more than one finger but the machine doesn’t know which finger you use… The other way around is also true. Like I said: most users only have one mouse but they are likely to have more than one finger. So how do we take that into account? Thinking about this is really worth the time: you might come up with some surprisingly good ideas! Still: don’t forget that not every user has touch-enabled hardware so make sure your app is useable for both groups. Keep this in mind: we’re going to need it later on! Now. Apps should be easy to use. You don’t want your user to read through pages and pages of documentation before they can use the app. Imagine that spotter next to an airfield suddenly seeing a prototype of a Concorde 2 landing on the nearby runway. He probably wants to enter that information in our app NOW and not after he’s taken a 3 day course. Even if he still has to download the app, install it for the first time and then run it he should be on his way immediately. At least, fast enough to note down the details of that unique, rare and possibly exciting sighting he just did. So.. How do we do this? Well, I am not talking about games here. Games are in a league of their own. They fall outside the scope of the apps I am describing. But all the others can roughly be characterized as being one of two flavors: the navigation is either flat or hierarchical. That’s it. And if it’s hierarchical it’s no more than three levels deep. Not more. Your users will get lost otherwise and we don’t want that. Flat is simple. Just imagine we have one screen that is as high as our physical screen is and as wide as you need it to be. Don’t worry if it doesn’t fit on the screen: people can scroll to the right and left. Don’t combine up/down and left/right scrolling: it’s confusing. Next to that, since most users will hold their device in landscape mode it’s very natural to scroll horizontal. So let’s use that when we have a flat model. The same applies to the hierarchical model. Try to have at most three levels. If you need more space, find a way to group the items in such a way that you can fit it in three, very wide lanes. At the highest level we have the so called hub level. This is the entry point of the app and as such it should give the user an immediate feeling of what the app is all about. If your app has categories if items then you might show these categories here. And while you’re at it: also show 2 or 3 of the items itself here to give the user a taste of what lies beneath. If the user selects a category you go to the section part. Here you show several sections (again, go as wide as you need) with again some detail examples. After that: the details layer shows each item. By giving some samples of the underlaying layer you achieve several things: you make the layer attractive by showing several different things, you show some highlights so the user sees actual content and you provide a shortcut to the layers underneath. The image below is borrowed from the http://design.windows.com website which has tons and tons of examples: For our app we’ll use this layout. So what will we show? Well, let’s see what sorts of features our app has to offer. I’ll repeat them here: Note planes Add pictures of that plane Notify friends of new spots Share new spots on social media Write down arrival times Write down departure times Write down the runway they take I am sure you can think of some more items but for now we'll use these. In the hub we’ll show something that represents “Spots”, “Friends”, “Social”. Apparently we have an inner list of spotter-friends that are in the app, while we also have to whole world in social. In the layer below we show something else, depending on what the user choose. When they choose “Spots” we’ll display the last spots, last spots by our friends (so we can actually jump from this category to the one next to it) and so on. When they choose a “spot” (or press the + icon in the App bar, which I’ll talk about next time) they go to the lowest and final level that shows details about that spot, including a picture, date and time and the notes belonging to that entry. You’d be amazed at how easy it is to organize your app this way. If you don’t have enough room in these three layers you probably could easily get away with grouping items. Take a look at our hub: we have three completely different things in one place. If you still can’t fit it all in in a logical and consistent way, chances are you are trying to do too much in this app. Go back to your mission statement, determine if it is specific enough and if your feature list helps that statement or makes it unclear. Go ahead. Give it a go! Next time we’ll talk about the look and feel, the charms and the app-bar….

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  • Companies and Ships

    - by TechnicalWriting
    I have worked for small, medium, large, and extra large companies and they have something in common with ships. These metaphors have been used before, I know, but I will have a go at them.The small company is like a speed boat, exciting and fast, and can turn on a dime, literally. Captain and crew share a lot of the work. A speed boat has a short range and needs to refuel a lot. It has difficulty getting through bad weather. (Small companies often live quarter to quarter. By the way, if a larger company is living quarter to quarter, it is taking on water.)The medium company is is like a battleship. It can maneuver, has a longer range, and the crew is focused on its mission. Its main concern are the other battleships trying to blow it out of the water, but it can respond quickly. Bad weather can jostle it, but it can get through most storms.The large company is like an aircraft carrier; a floating city. It is well-provisioned and can carry a specialized load for a very long range. Because of its size and complexity, it has to be well-organized to be effective and most of its functions are specialized (with little to no functional cross-over). There are many divisions and layers between Captain and crew. It is not very maneuverable; it has to set its course well in advance and have a plan of action.The extra large company is like a cruise liner. It also has to be well-organized and changes in direction are often slow. Some of the people are hard at work behind the scenes to run the ship; others can be along for the ride. They sail the same routes over and over again (often happily) with the occasional cosmetic face-lift to the ship and entertainment. It should stay in warm, friendly waters and avoid risky speed through fields of ice bergs.I have enjoyed my career on the various Ships of Technical Writing, but I get the most of my juice from the battleship where I am closer to the campaign and my contributions have the greater impact on success.Mark Metcalfewww.linkedin.com/in/MarkMetcalfe

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  • ORM and component-based architecture

    - by EagleBeek
    I have joined an ongoing project, where the team calls their architecture "component-based". The lowest level is one big database. The data access (via ORM) and business layers are combined into various components, which are separated according to business logic. E.g., there's a component for handling bank accounts, one for generating invoices, etc. The higher levels of service contracts and presentation are irrelevant for the question, so I'll omit them here. From my point of view the separation of the data access layer into various components seems counterproductive, because it denies us the relational mapping capabilities of the ORM. E.g., when I want to query all invoices for one customer I have to identify the customer with the "customers" component and then make another call to the "invoices" component to get the invoices for this customer. My impression is that it would be better to leave the data access in one component and separate it from business logic, which may well be cut into various components. Does anybody have some advice? Have I overlooked something?

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  • how to properly implement alpha blending in a complex 3d scene

    - by Gajet
    I know this question might sound a bit easy to answer but It's driving me crazy. There are too many possible situations that a good alpha blending mechanism should handle, and for each Algorithm I can think of there is something missing. these are the methods I've though about so far: first of I though about object sorting by depth, this one simply fails because Objects are not simple shapes, they might have curves and might loop inside each other. so I can't always tell which one is closer to camera. then I thought about sorting triangles but this one also might fail, thought I'm not sure how to implement it there is a rare case that might again cause problem, in which two triangle pass through each other. again no one can tell which one is nearer. the next thing was using depth buffer, at least the main reason we have depth buffer is because of the problems with sorting that I mentioned but now we get another problem. Since objects might be transparent, in a single pixel there might be more than one object visible. So for which Object should I store pixel depth? I then thought maybe I can only store the most front Object depth, and using that determine how should I blend next draw calls at that pixel. But again there was a problem, think about 2 semi transparent planes with a solid plane in middle of them. I was going to render the solid plane at the end, one can see the most distant plane. note that I was going to merge every two planes until there is only one color left for that pixel. Obviously I can use sorting methods too because of the same reasons I've explained above. Finally the only thing I imagine being able to work is to render all objects into different render targets and then sort those layers and display the final output. But this time I don't know how can I implement this algorithm.

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  • Unity Problem with colliding instances of same object

    - by Kuba Sienkiewicz
    I want to check if object's instance is overlapping with another instance (any spawned object with another spawned object, not necessary the same object). I'm doing this by detecting collisions between bodies. But I have a problem. Spawned object (instances) are detecting collision with everything but other spawned objects. I've checked collision layers etc. All of spawned objects have rigidbodies and mesh colliders. Also when I attach my script to another body and I touch that body with an instanced object it detects collision. So problem is visible only in collision between spawned objects. And one more information I have script, rigid body and collider attached to child of main object. using UnityEngine; using System.Collections; public class CantPlace : MonoBehaviour { public bool collided = false; // Use this for initialization void Start () { } // Update is called once per frame void Update () { //Debug.Log (collided); } void OnTriggerEnter(Collider collider) { //if (true) { //foreach (Transform child in this.transform) { // if (child.name == "Cylinder") { //collided = true; Color c; c = this.renderer.material.color; c.g = 0f; c.b = 1f; c.r = 0f; this.renderer.material.color = c; Debug.Log (collider.name); //} // } //} //foreach (ContactPoint contact in collision.contacts) { // Debug.DrawRay(contact.point, contact.normal, Color.red,15f); // } } }

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  • Possible to draw a select portion of a render target? (in XNA)

    - by TheBroodian
    I'm going to try to do this in reverse fashion and skip straight to the punch line, and then give the back story afterward: Is it possible to, after drawing a scene to a RenderTarget2D, only draw a select portion of the RenderTarget2D, if I don't want the entire thing? I'm using xTile to manage world data in my game (it's a great piece of work, colinvella [xTile's author] has made an amazing product), and for the most part it works great. xTile supports parallax effects in its layers to add some wonderful depth to 2d scenes, which was great, until I implemented a dynamic split-screen system into my game. Wanted to make a co-op game that wouldn't require players to be in close proximity to each other, so I made it so that if the players separate too far apart, the singular full-screen viewport 'snaps-apart', and is replaced by two split-screen viewports, which then smoothly transition to their respective player targets. The effect is pretty smooth aside from the part where the parallax backgrounds become skewed once the viewports split, because xTile's ratio for handling parallax effects is dependent upon viewport size. This is unfortunate, because the effect would otherwise be really snazzy, but the backgrounds become pretty heavily affected when the game goes from single-viewport to multi-viewport. So, Colinvella suggests using rendertargets to record the scene at full viewport size, and then only drawing a portion of it. But as far as I can tell, that isn't even possible? That being said, I've never even used render targets before, so I'm still learning, hence the question here.

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  • svcbundle for easier SMF manifest creation

    - by Glynn Foster
    One of the new features we've introduced in Oracle Solaris 11.1 is a new utility called svcbundle. This utility allows for the easy creation of Service Management Facility (SMF) manifests and profiles, allowing you to take advantage of the benefits of automatic application restart without requiring you to have full knowledge of the XML file format that is used when integrating with the SMF. Integrating into SMF is one of the easiest and most obvious ways to take advantage of some of the mission critical aspects of the operating system, but many customers were often finding the initial learning curve of creating an XML manifest to be too hard. With the release of Oracle Solaris 11 11/11, SMF had a more integral part to play as more and more system configuration was starting to use the SMF configuration repository for the backend storage. This provides a number of aspects, including the ability to carefully manage customized administrative configuration, site specific configuration, and vendor provided configuration at different layers, helping to preserve them during system update. I've written a new article, Using svcbundle to Create SMF Manifests and Profiles in Oracle Solaris 11, to give you a feel for the help we can provide in converting your applications over to SMF, or doing some site wide configuration using profiles. This is the first pass at creating such a tool, so we'd love to hear feedback of your experiences using it.

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  • canvas tile grid, hover effects, single tilesheet, etc

    - by user121730
    I'm currently in the process of building both the client and server side of an html5, canvas, and WebSocket game. This is what I have thus far for the client: http://jsfiddle.net/dDmTf/7/ Current obstacles The hover effect has no idea what to put back after the mouse leaves. Currently it's just drawing a "void" tile, but I can't figure out how to redraw a single tile without redrawing the whole map. How would I go about storing multiple layers within the map variable? I was considering just using a multi-dimensional array for each layer (similar to what you see as the current array), and just iterating through it, but is that really an efficient way of doing it? Side note The tile sheet being used for the jsfiddle display is only for development. I'll be replacing it as things progress in the engine. I hope you can help! Hopefully you guys can help me, I've been struggling to get through things, since I'm learning how things kind of stuff works as I go. If you guys have any pointers for my JavaScript, feel free. As I'm more or less learning advanced usage as I go, I'm sure I'm doing plenty of things wrong. Note: I will continue to update this post as the engine improves, but updating the jsfiddle link and updating the obstacles list by striking things that have been solved, or adding additions. Thanks!

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  • Entity framework separating entities for product and customer specific implementation

    - by Codecat
    I am designing an application with intention into making it a product line. I would like to extend the functionality across all layers and first struggle is with domain models. For example, core functionality would have entity named Invoice with few standard fields and then customer requirements will add some new fields to it, but I don't want to add to core Invoice class. For every customer I could use customer specific DbContext and injected correct context with dependency injection. Also every customer will get they own deployment public class Product.Domain.Invoice { public int InvoiceId { get; set; } // Other fields } How to approach this problem? Solution 1 does not work since Entity Framework does not allow same simple name classes. public class CustomerA.Domain.Invoice : Product.Domain.Invoice { public User ReviewedBy { get; set; } public DateTime? ReviewedOn { get; set; } } Solution 2 Create separate table and link it to core domain table. Reusing services and controllers could be harder. public class CustomerA.Domain.CustomerAInvoice { public Product.Domain.Invoice Invoice { get; set; } public User ReviewedBy { get; set; } public DateTime? ReviewedOn { get; set; } }

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  • Is there really anything to gain with complex design? [duplicate]

    - by SB2055
    This question already has an answer here: What is enterprise software, exactly? 8 answers I've been working for a consulting firm for some time, with clients of various sizes, and I've seen web applications ranging in complexity from really simple: MVC Service Layer EF DB To really complex: MVC UoW DI / IoC Repository Service UI Tests Unit Tests Integration Tests But on both ends of the spectrum, the quality requirements are about the same. In simple projects, new devs / consultants can hop on, make changes, and contribute immediately, without having to wade through 6 layers of abstraction to understand what's going on, or risking misunderstanding some complex abstraction and costing down the line. In all cases, there was never a need to actually make code swappable or reusable - and the tests were never actually maintained past the first iteration because requirements changed, it was too time-consuming, deadlines, business pressure, etc etc. So if - in the end - testing and interfaces aren't used rapid development (read: cost-savings) is a priority the project's requirements will be changing a lot while in development ...would it be wrong to recommend a super-simple architecture, even to solve a complex problem, for an enterprise client? Is it complexity that defines enterprise solutions, or is it the reliability, # concurrent users, ease-of-maintenance, or all of the above? I know this is a very vague question, and any answer wouldn't apply to all cases, but I'm interested in hearing from devs / consultants that have been in the business for a while and that have worked with these varying degrees of complexity, to hear if the cool-but-expensive abstractions are worth the overall cost, at least while the project is in development.

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  • Is there a typical career path to learn game development "on the job"?

    - by mac
    The extended version of the question is: what is the typical career paths that a developer without specific experience in game development should take if he/she wishes to work in the game development industry? In other words, what are the positions such a programmer might aspire to get hired for, in the game industry? I am asking because it seems to me that - even without direct experience with 3D modelling, physics engines, shaders, etc... - for as much complex as these topics might be - they are still "just" top layers one can learn "on the job" if he/she has already good programming skills and experience in software design (for example during peer-programming sessions). I have no knowledge whatsoever of the game industry, so maybe I am being naïve here, but for all the other programming jobs I previously took, I learnt most of the specificities while working on concrete projects... so I wonder if there is a chance to do the same with game development. Thanks for your time and advice! :) PS: I don't know if this is important or not for answering the question, but scripting languages are the languages I am more proficient in. /mac

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  • Designing a system with different business rules for different customers

    - by user1595846
    My company is rewriting our proprietary business application. The current architecture is poorly done and inflexible. It is coded more procedural oriented as opposed to object oriented. It has become difficult to maintain. Our system is a web application written in .Net Webforms. I am considering ASP.Net MVC for the rewrite. We intend to rewrite it with a good, solid architecture with the goal of maintainability and reusable classes for some of our other systems and services. We would also like the system to be customizable for different customers in the event that we market the system. I am considering redesigning the system based on the layered architecture (Presentation, Business, Data Access layers) described in the Microsoft Patterns and Practices Application Architecture Guide. http://msdn.microsoft.com/en-us/library/ff650706.aspx Hopefully this isn't too open ended, but how would you recommend allowing for different business logic/rules for different customers? I'm aware of Windows Workflow Foundation, but from what I've read about it, it seems many business rules could be too complicated to handle there. Also, Can anyone point me to where I can download an example of a .net solution that is based on the Application Architecture Guide? I have already downloaded the Layered Architecture Solution Guidance and the Expense Sample on codeplex. I was looking for something a bit larger and more robust that I could step through the code and see how it works. If you feel there are better architectures to base our redesign on please feel free to share. I appreciate your help!

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  • Having the same texture data in different ID3D11Texture2D

    - by bdmnd
    Sorry if this has been answered elsewhere - I'm rather new to DX. My question concerns conservation of resources - specifically textures in VRAM. I assume that upon returning from a call to CreateTexture2D, a copy of any textures data supplied has been copied elsewhere, likely VRAM. Does DX11 have any facility for having multiple ID3D11Texture2D objects which point to the same data? This might at first seem silly, but imagine a ID3D11Texture2D which is an array of textures. In one material, an artist has chosen to blend three identically sized maps, saved on disk as A.dds, B.dds, and C.dds. Then imagine they have another material which also uses three maps, but this time A.dds, B.dds, and D.dds. The shader code knows the diffuse texture is a texture array, and also has the number of layers baked (three in each case). I would essentially like to set up just two ID3D11Texture2D objects, one for each material, but I don't want to waste VRAM for two identical copies of A.dds and B.dds. I could use explicit texture arrays, of course, but this reduces the number of resources available to the shader and can complicate code somewhat more than would otherwise be needed.

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  • how to calculate intersection time and place of multiple moving arcs

    - by user20733
    I have rocks orbiting moons, moons orbiting planets, planets orbiting suns, and suns orbiting black holes, and the current system could have many many layers of orbitage. the position of any object is a function of time and relative to the object it orbits. (so far so good). now I want to know for a given 2 objects(A,B), a start time and a speed, how can I work out the when and where to go. I can work out where A and B is given a time. so i just need. 1: direction to travel in from A to B(remember B is moving(not in a straight line)) 2: Time to get to b in a straight line. travel must be in a straight line with the shortest possible distance. as an extension to this question, how will i know if its better to wait, EG is it faster to stay on object A and wait for a hour when the objects may be closer, than to set off from A to B at the start. Cheers, it hurt my brain.

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  • Clustering Strings on the basis of Common Substrings

    - by pk188
    I have around 10000+ strings and have to identify and group all the strings which looks similar(I base the similarity on the number of common words between any two give strings). The more number of common words, more similar the strings would be. For instance: How to make another layer from an existing layer Unable to edit data on the network drive Existing layers in the desktop Assistance with network drive In this case, the strings 1 and 3 are similar with common words Existing, Layer and 2 and 4 are similar with common words Network Drive(eliminating stop word) The steps I'm following are: Iterate through the data set Do a row by row comparison Find the common words between the strings Form a cluster where number of common words is greater than or equal to 2(eliminating stop words) If number of common words<2, put the string in a new cluster. Assign the rows either to the existing clusters or form a new one depending upon the common words Continue until all the strings are processed I am implementing the project in C#, and have got till step 3. However, I'm not sure how to proceed with the clustering. I have researched a lot about string clustering but could not find any solution that fits my problem. Your inputs would be highly appreciated.

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  • How to revert to Eclipse's old behavior when double-clicking on frames or windows, in Juno?

    - by mattquiros
    I find Eclipse Juno very counter-intuitive. In my workspace, I used to just have the package view at the left, my code on the right, and whenever I'm printing something in the console, that's only when the console frame shows up from the bottom right. When you double click on a particular window, it either only goes fullscreen within Eclipse, or back to its original size together with the size of the other frames. In Juno, however, it seems that frames are put on layers on top of each other. When I print something to the console, the output frame only shows up as a small, useless square to my right. When I double-click, it goes full screen. When I double-click again, it occupies the full right frame, hiding my code. I double-click again and it goes full screen, then it double-clicks before it shares the right frame with my code on top of it. Then when I minimize it, it goes to the side. Any way to go back to the good old days of Eclipse? Thanks.

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