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• Using the Coherence ConcurrentMap Interface (Locking API)

  - by jpurdy

  For many developers using Coherence, the first place they look for concurrency control is the com.tangosol.util.ConcurrentMap interface (part of the NamedCache interface). The ConcurrentMap interface includes methods for explicitly locking data. Despite the obvious appeal of a lock-based API, these methods should generally be avoided for a variety of reasons: They are very "chatty" in that they can't be bundled with other operations (such as get and put) and there are no collection-based versions of them. Locks do directly not impact mutating calls (including puts and entry processors), so all code must make explicit lock requests before modifying (or in some cases reading) cache entries. They require coordination of all code that may mutate the objects, including the need to lock at the same level of granularity (there is no built-in lock hierarchy and thus no concept of lock escalation). Even if all code is properly coordinated (or there's only one piece of code), failure during updates that may leave a collection of changes to a set of objects in a partially committed state. There is no concept of a read-only lock. In general, use of locking is highly discouraged for most applications. Instead, the use of entry processors provides a far more efficient approach, at the cost of some additional complexity.

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• How to retrieve connection details of CheckPoint SSL Network Extender?

  - by amoe

  My workplace uses a Java-based VPN tool named CheckPoint SSL Network Extender. I would like to configure the VPN connection myself using stock OS tools, because I find the applet to be rather unstable. How would I go about getting all of the connection details needed to manually connect to the VPN? My workplace only supports the official client. When I am connected with the Java applet, if I run ipconfig /all I can see that a hidden network connection is created named Check Point Virtual Network Adapter For SSL Network Extender - Packet Scheduler Miniport. I can see the various IP and DNS details there as well. However, because I need to log in to the applet-based tool, I presume I need to export some kind of key in order to use OS tools to configure this. Is this even possible? Answers for any OS are great although I am using Windows XP to test, and also want to use Linux clients.

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• BPM 11g Hands on Training

  - by mseika

  BPM 11g Hands on Training11-14 December 2012, Birmingham (UK) DescriptionThis free hands-on workshop covers the life cycle of a business process from analysis, modeling, simulation, process customization and monitoring using Oracle BPM Suite 11g. The process modeled in the workshop includes integrating with web services, creating complex human workflows with user interfaces for task forms and incorporating rule engine-based decision services. After taking this course on Oracle BPM Suite 11g, you can go onto build industry-focused solutions, customer-facing demos, proof-of-concepts (POCs), pilot implementations and reference architectures. REGISTER NOW Partner Registration Guide Price: FREE Address:Hockley Suite - Oracle OfficesBlythe Valley Business ParkShirley, SolihullWest Midlands B90 8ADUnited Kingdom 11 - 14 December 2012 You will also be able to extend your current SOA implementations with BPMN based business processes.You will have the opportunity to sit the BPM 11g Implementation Specialization exam at the end of the boot camp. The training will finish at 3pm on Friday 14th to allow time for the on-line exam to take place. AgendaThis workshop is 4 days long. 08:30 am: Arrival and sign-in09:00 am: Workshop begins 17:30 pm: Workshop ends (more detail to be provided) Workstation RequirementsAttendees must use their own laptops and it is essential they have the following:           · Minimum 8GB RAM. 40GB free disk space           · VirtualBox (latest version)           ·7zip (required for extracting the VirtualBox image) For more information please contact [email protected].

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• If an entity is composed, is it still a god object?

  - by Telastyn

  I am working on a system to configure hardware. Unfortunately, there is tons of variety in the hardware, which means there's a wide variety of capabilities and configurations depending on what specific hardware the software connects to. To deal with this, we're using a Component Based Entity design where the "hardware" class itself is a very thin container for components that are composed at runtime based on what capabilities/configuration are available. This works great, and the design itself has worked well elsewhere (particularly in games). The problem is that all this software does is configure the hardware. As such, almost all of the code is a component of the hardware instance. While the consumer only ever works against the strongly typed interfaces for the components, it could be argued that the class that represents an instance of the hardware is a God Object. If you want to do anything to/with the hardware, you query an interface and work with it. So, even if the components of an object are modular and decoupled well, is their container a God Object and the downsides associated with the anti-pattern?

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• knowing all available entity types

  - by plofplof

  I'm making a game where at some point the game will create enemies of random types. Each type of enemy available is defined on its own class derived from an enemy superclass. To do this, obviously the different types of enemies should be known. This is what I have thought of: Just make a list manually. Very simple to do, but I don't like it because I'll be adding more enemy types over time, so any time I add a new class I have to remember to update this (same if I remove an enemy). I would like some kind of auto-updating list. A completely component based system. There are no different classes for each enemy, but definitions of enemies in some file where all enemy types can be found. I really don't need that level of complexity for my game. I'm still using a component based model to some degree, but each Enemy type gets defined on its own class. Java Annotation processing. Give each enemy subclass an annotation like @EnemyType("whatever"), then code an annotation processor that writes in a file all available enemy types. Any time a new class is added the file gets updated after compilation.This gives me a feeling of failure even if its a good solution, it's very dependant on Java, so it means I cant think of a general design good for any kind of language. Also I think that this would be too much work for something so simple. I would like to see comments on these ideas and other possible solutions Thanks

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• WCF Publish/Subscribe and using callbacks to send data to specific users

  - by manemawanna

  Hello thanks for looking, I'm working on a project at the moment and have become a little stuck. I'm creating a client server app, which allows a client to subscribe to the server to have messages forwarded to it. The issue I'm having is that when the client subscribes I wish for them to only recieve updates that relate to them. The system basically passes messages from a SQL server DB which the server monitors. When a new message is recieved the server should only forward the message to the clients that it applys to, based on whos logged on the client machine. I've had a look and found code samples which sign up for messages to be broadcast across all clients who have subscribed, but not any that show how to identify individual clients and if messages apply to them. If anyone could help or point me in the right direction it would be appreciated. You can now find some of my code below: namespace AnnouncementServiceLibrary { [ServiceContract(CallbackContract = typeof(IMessageCallback))] public interface IMessageCheck { [OperationContract] void MessageCheck(); } } namespace AnnouncementServiceLibrary { public interface IMessageCallback { [OperationContract(IsOneWay = true)] void OnNewMessage(Mess message); } } public bool Subscribe() { try { IMessageCallback callback = OperationContext.Current.GetCallbackChannel<IMessageCallback>(); //If they dont already exist in the subscribers list, adds them to it if (!subscribers.Contains(callback)) subscribers.Add(callback); return true; } catch { //Otherwise if an error occurs returns false return false; } } Subscribe/Unsubscribe: private static readonly List<IMessageCallback> subscribers = new List<IMessageCallback>(); /// <summary> /// Unsubscribes the user from recieving new messages when they become avaliable /// </summary> /// <returns>Returns a bool that indicates whether the operation worked or not</returns> public bool Unsubscribe() { try { IMessageCallback callback = OperationContext.Current.GetCallbackChannel<IMessageCallback>(); //If they exist in the list of subscribers they are then removed if (subscribers.Contains(callback)) subscribers.Remove(callback); return true; } catch { //Otherwise if an error occurs returns false return false; } } Finally this at the moment isnt't working as basically when a user subscribes as it loops through I want it to filter based on the users userID: #region IMessageCheck Members /// <summary> /// This method checks for new messages recieved based on those who have subscribed for the service /// </summary> public void MessageCheck() { //A continuous loop to keep the method going while(true) { //Changes the thread to a sleep state for 2 mins? Thread.Sleep(200000); //Go through each subscriber based on there callback information subscribers.ForEach(delegate(IMessageCallback callback) { //Checks if the person who wanted the callback can still be communicated with if (((ICommunicationObject)callback).State == CommunicationState.Opened) { //Creates a link to the database and gets the required information List<Mess> mess = new List<Mess>(); List<Message> me; List<MessageLink> messLink; AnnouncementDBDataContext aDb = new AnnouncementDBDataContext(); me = aDb.Messages.ToList(); messLink = aDb.MessageLinks.ToList(); //Query to retrieve any messages which are newer than the time when the last cycle finished var result = (from a in messLink join b in me on a.UniqueID equals b.UniqueID where b.TimeRecieved > _time select new { b.UniqueID, b.Author, b.Title, b.Body, b.Priority, a.Read, b.TimeRecieved }); //Foreach result a new message is created and returned to the PC that subscribed foreach (var a in result) { Mess message = new Mess(a.UniqueID, a.Author, a.Title, a.Body, a.Priority, (bool)a.Read, a.TimeRecieved); callback.OnNewMessage(message); } } //If the requesting PC can't be contacted they are removed from the subscribers list else { subscribers.Remove(callback); } }); //Sets the datetime so the next cycle can measure against to see if new messages have been recieved _time = DateTime.Now; } } #endregion

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• Modern Java alternatives

  - by Ralph

  I'm not sure if stackoverflow is the best forum for this discussion. I have been a Java developer for 14 years and have written an enterprise-level (~500,000 line) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for the stackoverflow readerships' opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. If anyone has a suggestion for another JVM-based language that can be used for enterprise level development, please list it. Also, it is not my intent to start a flame war. Thanks, Ralph

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• Jquery getJSON cross domain problems

  - by Charlie

  I cant seem to get my JSON file to work when pulling it in from another domain using JQuerys getJSON. I have placed the callback part at the end of the url but still have no joy. Firebug tells me its a cross domain issue, which seems to make sense as if I place the json file locally the below code (excluding the ?jsoncallback=? works fine) Heres the Jquery part $.getJSON("http://anotherdomain/js/morearticles.js?jsoncallback=?", function(json){ if (show5More.nextSetCount ' + this.titletext + '' + this.paratext + '').appendTo("#lineupswitch"); } else { $('' + this.titletext + '' + this.paratext + '').appendTo("#lineupswitch"); } }); return false; } }); } }); } And the JSON, which I have validated. { "items": [ [ { "href": "/edinburgh/video/news-090415-s2-squalor-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19721015001_asset-1239819553334.jpg?pubId=1486976045", "titletext": "Cannabis plants found in house with neglected children", "paratext": "A court has heard four young children lived in", "cname": "" }, { "href": "/edinburgh/video/news-090414-s2-waverley-station-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19537855001_asset-1239732920496.jpg?pubId=1486976045", "titletext": "Multi-million pound revamp for Waverley Station", "paratext": "Edinburgh's Waverley Station is set for a", "cname": "" }, { "href": "/edinburgh/video/news-s2-natal-20090408/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18948154001_asset-1239206353135.jpg?pubId=1486976045", "titletext": "Stillbirth charity on the road to raise awareness", "paratext": "SANDS Lothian are hoping to highlight their", "cname": "" }, { "href": "/edinburgh/video/news-090407-l2-rbs/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18827378001_asset-1239110600777.jpg?pubId=1486976045", "titletext": "Thousands of jobs to go at Royal Bank of Scotland", "paratext": "Edinburgh-based bank to cut 4,500 positions in the", "cname": "" }, { "href": "/edinburgh/video/news-090415-s2-squalor-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19721015001_asset-1239819553334.jpg?pubId=1486976045", "titletext": "1", "paratext": "A court has heard four young children lived in", "cname": "lastlineup" } ], [ { "href": "/edinburgh/video/news-090415-s2-squalor-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19721015001_asset-1239819553334.jpg?pubId=1486976045", "titletext": "1", "paratext": "A court has heard four young children lived in", "cname": "" }, { "href": "/edinburgh/video/news-090414-s2-waverley-station-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19537855001_asset-1239732920496.jpg?pubId=1486976045", "titletext": "2", "paratext": "Edinburgh's Waverley Station is set for a", "cname": "" }, { "href": "/edinburgh/video/news-s2-natal-20090408/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18948154001_asset-1239206353135.jpg?pubId=1486976045", "titletext": "Stillbirth charity on the road to raise awareness", "paratext": "3", "cname": "" }, { "href": "/edinburgh/video/news-090407-l2-rbs/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18827378001_asset-1239110600777.jpg?pubId=1486976045", "titletext": "Thousands of jobs to go at Royal Bank of Scotland", "paratext": "4", "cname": "" }, { "href": "/edinburgh/video/news-090407-l2-rbs/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18827378001_asset-1239110600777.jpg?pubId=1486976045", "titletext": "Thousands of jobs to go at Royal Bank of Scotland", "paratext": "Edinburgh-based bank to cut 4,500 positions in the", "cname": "lastlineup" } ] ] } { "items": [ [ { "href": "/edinburgh/video/news-090415-s2-squalor-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19721015001_asset-1239819553334.jpg?pubId=1486976045", "titletext": "Cannabis plants found in house with neglected children", "paratext": "A court has heard four young children lived in", "cname": "" }, { "href": "/edinburgh/video/news-090414-s2-waverley-station-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19537855001_asset-1239732920496.jpg?pubId=1486976045", "titletext": "Multi-million pound revamp for Waverley Station", "paratext": "Edinburgh's Waverley Station is set for a", "cname": "" }, { "href": "/edinburgh/video/news-s2-natal-20090408/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18948154001_asset-1239206353135.jpg?pubId=1486976045", "titletext": "Stillbirth charity on the road to raise awareness", "paratext": "SANDS Lothian are hoping to highlight their", "cname": "" }, { "href": "/edinburgh/video/news-090407-l2-rbs/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18827378001_asset-1239110600777.jpg?pubId=1486976045", "titletext": "Thousands of jobs to go at Royal Bank of Scotland", "paratext": "Edinburgh-based bank to cut 4,500 positions in the", "cname": "" }, { "href": "/edinburgh/video/news-090415-s2-squalor-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19721015001_asset-1239819553334.jpg?pubId=1486976045", "titletext": "1", "paratext": "A court has heard four young children lived in", "cname": "lastlineup" } ], [ { "href": "/edinburgh/video/news-090415-s2-squalor-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19721015001_asset-1239819553334.jpg?pubId=1486976045", "titletext": "1", "paratext": "A court has heard four young children lived in", "cname": "" }, { "href": "/edinburgh/video/news-090414-s2-waverley-station-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19537855001_asset-1239732920496.jpg?pubId=1486976045", "titletext": "2", "paratext": "Edinburgh's Waverley Station is set for a", "cname": "" }, { "href": "/edinburgh/video/news-s2-natal-20090408/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18948154001_asset-1239206353135.jpg?pubId=1486976045", "titletext": "Stillbirth charity on the road to raise awareness", "paratext": "3", "cname": "" }, { "href": "/edinburgh/video/news-090407-l2-rbs/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18827378001_asset-1239110600777.jpg?pubId=1486976045", "titletext": "Thousands of jobs to go at Royal Bank of Scotland", "paratext": "4", "cname": "" }, { "href": "/edinburgh/video/news-090407-l2-rbs/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18827378001_asset-1239110600777.jpg?pubId=1486976045", "titletext": "Thousands of jobs to go at Royal Bank of Scotland", "paratext": "Edinburgh-based bank to cut 4,500 positions in the", "cname": "lastlineup" } ] ] }

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• Languages and VMs: Features that are hard to optimize and why

  - by mrjoltcola

  I'm doing a survey of features in preparation for a research project. Name a mainstream language or language feature that is hard to optimize, and why the feature is or isn't worth the price paid, or instead, just debunk my theories below with anecdotal evidence. Before anyone flags this as subjective, I am asking for specific examples of languages or features, and ideas for optimization of these features, or important features that I haven't considered. Also, any references to implementations that prove my theories right or wrong. Top on my list of hard to optimize features and my theories (some of my theories are untested and are based on thought experiments): 1) Runtime method overloading (aka multi-method dispatch or signature based dispatch). Is it hard to optimize when combined with features that allow runtime recompilation or method addition. Or is it just hard, anyway? Call site caching is a common optimization for many runtime systems, but multi-methods add additional complexity as well as making it less practical to inline methods. 2) Type morphing / variants (aka value based typing as opposed to variable based) Traditional optimizations simply cannot be applied when you don't know if the type of someting can change in a basic block. Combined with multi-methods, inlining must be done carefully if at all, and probably only for a given threshold of size of the callee. ie. it is easy to consider inlining simple property fetches (getters / setters) but inlining complex methods may result in code bloat. The other issue is I cannot just assign a variant to a register and JIT it to the native instructions because I have to carry around the type info, or every variable needs 2 registers instead of 1. On IA-32 this is inconvenient, even if improved with x64's extra registers. This is probably my favorite feature of dynamic languages, as it simplifies so many things from the programmer's perspective. 3) First class continuations - There are multiple ways to implement them, and I have done so in both of the most common approaches, one being stack copying and the other as implementing the runtime to use continuation passing style, cactus stacks, copy-on-write stack frames, and garbage collection. First class continuations have resource management issues, ie. we must save everything, in case the continuation is resumed, and I'm not aware if any languages support leaving a continuation with "intent" (ie. "I am not coming back here, so you may discard this copy of the world"). Having programmed in the threading model and the contination model, I know both can accomplish the same thing, but continuations' elegance imposes considerable complexity on the runtime and also may affect cache efficienty (locality of stack changes more with use of continuations and co-routines). The other issue is they just don't map to hardware. Optimizing continuations is optimizing for the less-common case, and as we know, the common case should be fast, and the less-common cases should be correct. 4) Pointer arithmetic and ability to mask pointers (storing in integers, etc.) Had to throw this in, but I could actually live without this quite easily. My feelings are that many of the high-level features, particularly in dynamic languages just don't map to hardware. Microprocessor implementations have billions of dollars of research behind the optimizations on the chip, yet the choice of language feature(s) may marginalize many of these features (features like caching, aliasing top of stack to register, instruction parallelism, return address buffers, loop buffers and branch prediction). Macro-applications of micro-features don't necessarily pan out like some developers like to think, and implementing many languages in a VM ends up mapping native ops into function calls (ie. the more dynamic a language is the more we must lookup/cache at runtime, nothing can be assumed, so our instruction mix is made up of a higher percentage of non-local branching than traditional, statically compiled code) and the only thing we can really JIT well is expression evaluation of non-dynamic types and operations on constant or immediate types. It is my gut feeling that bytecode virtual machines and JIT cores are perhaps not always justified for certain languages because of this. I welcome your answers.

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• Modern alternatives to Java

  - by Ralph

  I have been a Java developer for 14 years and have written an enterprise-level (~500 kloc) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. Are there other JVM-based languages that can be used for enterprise level development?

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• Android - determine specific locations (X,Y coordinates) on a Bitmap on different resolutions?

  - by Mike

  My app that I am trying to create is a board game. It will have one bitmap as the board and pieces that will move to different locations on the board. The general design of the board is square, has a certain number of columns and rows and has a border for looks. Think of a chess board or scrabble board. Before using bitmaps, I first created the board and boarder by manually drawing it - drawLine & drawRect. I decided how many pixels in width the border would be based on the screen width and height passed in on "onSizeChanged". The remaining screen I divided by the number of columns or rows I needed. For examples sake, let's say the screen dimensions are 102 x 102. I may have chosen to set the border at 1 and set the number of rows & columns at 10. That would leave 100 x 100 left (reduced by two to account for the top & bottom border, as well as left/right border). Then with columns and rows set to 10, that would leave 10 pixels left for both height and width. No matter what screen size is passed in, I store exactly how many pixels in width the boarder is and the height & width of each square on the board. I know exactly what location on the screen to move the pieces to based on a simple formula and I know exactly what cell a user touched to make a move. Now how does that work with bitmaps? Meaning, if I create 3 different background bitmaps, once for each density, won't they still be resized to fit each devices screen resolution, because from what I read there were not just 3 screen resolutions, but 5 and now with tablets - even more. If I or Android scales the bitmaps up or down to fit the current devices screen size, how will I know how wide the border is scaled to and the dimensions of each square in order to figure out where to move a piece or calculate where a player touched. So far the examples I have looked at just show how to scale the overall bitmap and get the overall bitmaps width and height. But, I don't see how to tell how many pixels wide or tall each part of the board would be after it was scaled. When I draw each line and rectangle myself based in the screen dimensions from onSizeChanged, I always know these dimensions. If anyone has any sample code or a URL to point me to that I can a read about this with bitmaps, I would appreciate it. Thanks, --Mike BTW, here is some sample code (very simplified) on how I know the dimensions of my game board (border and squares) no matter the screen size. Now I just need to know how to do this with the board as a bitmap that gets scaled to any screen size. @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { intScreenWidth = w; intScreenHeight = h; // Set Border width - my real code changes this value based on the dimensions of w // and h that are passed in. In other words bigger screens get a slightly larger // border. intOuterBorder = 1; /** Reserve part of the board for the boardgame and part for player controls & score My real code forces this to be square, but this is good enough to get the point across. **/ floatBoardHeight = intScreenHeight / 4 * 3; // My real code actually causes floatCellWidth and floatCellHeight to // be equal (Square). floatCellWidth = (intScreenWidth - intOuterBorder * 2 ) / intNumColumns; floatCellHeight = (floatBoardHeight - intOuterBorder * 2) / intNumRows; super.onSizeChanged(w, h, oldw, oldh); }

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• Good locations worldwide for a coder gypsy wannabe

  - by fung

  Yes, this is not programming related but please bear with me =). I run a small niche SaaS business. Lately I've been thinking of traveling and experiencing life in other places. Would really appreciate suggestions for good places a developer could relocate to. In particular I'm looking for a place that: Has good internet connection (cheap stable broadband, lots of places that provide free wifi, etc.) Low cost of living (rent and food fairly cheap). At least half of the population speak English. Has a local courier agent (DHL, Fedex, any...). The government allows for extended stay of foreigners. I'm thinking of staying for about 6 months at each location and maybe doing it for 3 years. So looking for 5 to 6 locations in total. So if any of you think you're staying in a place that would be great for a visiting developer then please shout out. Include as detailed a description as possible. And include any cons about the place if there are. The only place that pops to mind right now is Bali =). Isle of Skye also seems interesting but I think immigration is tight and cost of living would definitely be higher. Thanks in advance for suggestions =)

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• HTML.CheckBox persisting state after POST - Refresh ModelState?

  - by Kirschstein

  I have a form that's made up of many items (think order items on an amazon order). Each row has a checkbox associated with them so the user can select many items and click 'remove'. The form is built up a bit like this; <% for (int i = 0; i < Model.OrderItems.Count; i++) { %> <tr> <td><%= Html.Hidden(String.Format("OrderItems[{0}].Id", i), Model.OrderItems[i].Id)%> <%= Html.CheckBox(String.Format("OrderItems[{0}].Checked", i), Model.OrderItems[i].Checked)%></td> <td><%= Html.TextBox(String.Format("OrderItems[{0}].Name", i), Model.OrderItems[i].Name)%></td> <td><%= Html.TextBox(String.Format("OrderItems[{0}].Cost", i), Model.OrderItems[i].Cost)%></td> <td><%= Html.TextBox(String.Format("OrderItems[{0}].Quantity", i), Model.OrderItems[i].Quantity)%></td> </tr> <% } %> The model binder does its magic just fine and the list is correctly populated. However, after I process the request in the action (e.g. remove the appropriate items) and return a new view containing fewer items, the state of the form is 'semi' persisted. Some check boxes remain checked, even though in the edit model all the bools are set to false. I don't have this problem if I return a RedirectToActionResult, but using that as a solution seems a bit of a hacky work around. I think I need to flush/refresh the ModelState, or something similiar, but I'm unsure of the terms to search for to find out how.

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• Could CouchDB benefit significantly from the use of BERT instead of JSON?

  - by Victor Rodrigues

  I appreciate a lot CouchDB attempt to use universal web formats in everything it does: RESTFUL HTTP methods in every interaction, JSON objects, javascript code to customize database and documents. CouchDB seems to scale pretty well, but the individual cost to make a request usually makes 'relational' people afraid of. Many small business applications should deal with only one machine and that's all. In this case the scalability talk doesn't say too much, we need more performance per request, or people will not use it. BERT (Binary ERlang Term http://bert-rpc.org/ ) has proven to be a faster and lighter format than JSON and it is native for Erlang, the language in which CouchDB is written. Could we benefit from that, using BERT documents instead of JSON ones? I'm not saying just for retrieving in views, but for everything CouchDB does, including syncing. And, as a consequence of it, use Erlang functions instead of javascript ones. This would modify some original CouchDB principles, because today it is very web oriented. Considering I imagine few people would make their database API public and usually its data is accessed by the users through an application, it would be a good deal to have the ability to configure CouchDB for working faster. HTTP+JSON calls could still be handled by CouchDB, considering an extra cost in these cases because of parsing.

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• shortest digest of a string

  - by meta

  [Description] Given a string of char type, find a shortest digest, which is defined as: a shortest sub-string which contains all the characters in the original string. [Example] A = "aaabedacd" B = "bedac" is the answer. [My solution] Define an integer table with 256 elements, which is used to record the occurring times for each kind of character in the current sub-string. Scan the whole string, statistic the total kinds of character in the given string by using the above table. Use two pointers, start, end, which are initially pointing to the start and (start + 1) of the given string. The current kinds of character is 1. Expand sub-string[start, end) at the end until it contains all kinds of character. Update the shortest digest if possible. Contract sub-string[start, end] at the start by one character each time, try to restore its digest property if necessary by step 4. The time cost is O(n), and the extra space cost is constant. Any better solution without extra space?

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• Compile android project to apk without eclipse

  - by sandis

  What I have done is I have taken the class-files from my eclipse project and run them trough an optimizer/obfuscator. So I now have optimized class-files that I want to get in the form of an apk so I can sign and publish it. However, I am lost on how to do this. I guess I cant just copy them into the bin-folder of my eclipse-project, because eclipse would just overwrite them with a new compilation when I try to export a signed apk. So how do I create an apk from these class-files? Cheers,

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• Starting a new business with former colleagues, advice needed

  - by Sparafusile

  I was recently contacted by a former boss of mine who is thinking of starting a new business. The business will be online only it will by my job to design, build, and maintain the software going into it. I will also have to maintain the server it's running on, being the only technical person on the team. I will be one of four members of the business, the other three being the actual business know-hows and salesmen. The other three are shouldering the cost of getting the business going (incorporation, attorney fees, etc) and we will be splitting the cost of the server. I have no business knowledge at all, and don't want any part of it, I am only interested in the technical aspects. Now that we are finalizing our plans, determining roles, and getting ready to start actual work, we have come to the point where we have to determine what percentage stake each of us has. Since I have never done anything like this before, or met anyone that has, I don't know what I should expect. Can anyone give me some pointers on what to ask for in this deal?

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• Operator issues with cout

  - by BSchlinker

  I have a simple package class which is overloaded so I can output package data simply with cout << packagename. I also have two data types, name which is a string and shipping cost with a double. protected: string name; string address; double weight; double shippingcost; ostream &operator<<( ostream &output, const Package &package ) { output << "Package Information ---------------"; output << "Recipient: " << package.name << endl; output << "Shipping Cost (including any applicable fees): " << package.shippingcost; The problem is occurring with the 4th line (output << "Recipient:...). I'm receiving the error "no operator "<<" matches these operands". However, line 5 is fine. I'm guessing this has to do with the data type being a string for the package name. Any ideas?

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• Development environment for ASP.NET with EpiServer

  - by Binary255

  At our company we are going to develop more for the Windows platform than we have done up until now. As this scale of Windows development is new to us it would be nice with some feedback from experienced developers. Requirements we have: 5 developers from the beginning. 15 developers a year from now. All developers should be able to develop at the same time. Be able to develop solution for ASP.NET and EpiServer 5. Our idea: A shared server which developers use for development through Terminal Services. SQL Server Express. Start with some free express edition of Visual Studio, upgrade to a commercial version if we need the additional features. Use IIS and not the web server built into Visual Studio. Questions: Are we on the right track? In terms of license costs the above should be cheapest, right? What do you think about multiple developers doing development using a shared TS-server? Do you know of any company which has a similar development environment? Are we going to miss some features of the full Visual Studio version immediately? Is using Express version a bad choice? Is IIS the best choice? If use IIS the developers may use the same port for deployment. If we use the built in web server each one has to set their own port as we're sharing a machine. Comment answer: We are thinking about a shared server as it will most likely decrease the license costs. So it's purely a cost issue. We are using CVS for version control. Our situation is that we develop on Mac and Linux, that's why buying 1 server license + Visual Studio licenses seems to be a cost effective way of starting this type of development.

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• Database Design Question regaurding duplicate information.

  - by galford13x

  I have a database that contains a history of product sales. For example the following table CREATE TABLE SalesHistoryTable ( OrderID, // Order Number Unique to all orders ProductID, // Product ID can be used as a Key to look up product info in another table Price, // Price of the product per unit at the time of the order Quantity, // quantity of the product for the order Total, // total cost of the order for the product. (Price * Quantity) Date, // Date of the order StoreID, // The store that created the Order PRIMARY KEY(OrderID)); The table will eventually have millions of transactions. From this, profiles can be created for products in different geographical regions (based on the StoreID). Creating these profiles can be very time consuming as a database query. For example. SELECT ProductID, StoreID, SUM(Total) AS Total, SUM(Quantity) QTY, SUM(Total)/SUM(Quantity) AS AvgPrice FROM SalesHistoryTable GROUP BY ProductID, StoreID; The above query could be used to get the Information based on products for any particular store. You could then determine which store has sold the most, has made the most money, and on average sells for the most/least. This would be very costly to use as a normal query run anytime. What are some design descisions in order to allow these types of queries to run faster assuming storage size isn’t an issue. For example, I could create another Table with duplicate information. Store ID (Key), Product ID, TotalCost, QTY, AvgPrice And provide a trigger so that when a new order is received, the entry for that store is updated in a new table. The cost for the update is almost nothing. What should be considered when given the above scenario?

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• Assert parameters in a table-valued UDF

  - by Clay Lenhart

  Is there a way to create "asserts" on the parameters of a table-valued UDF. I'd like to use a table-valued UDF for performance reasons, however I know that certain parameter combinations (like start and end dates that are more than a month apart) will cause performance issues on the server for all users. End users query the database via Excel using UDFs. UDFs (and table-valued UDFs in particular) are useful when the data is too large for Excel. Users write simple SQL queries that categorizes the data into groups to reduce the number of rows. For example, the user may be interested in weekly aggregates rather than hourly ones. Users write a group by SELECT statement to reduce the rows by 24x7=168 times. I know I can write RAISERROR statements in multistatement UDFs, but table-valued UDFs are integrated in the query optimizer so these queries are more efficient with table-valued UDFs. So, can I define assertions on the parameters passed to a table-valued UDF?

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• SQL Server insert performance

  - by Jose

  I have an insert query that gets generated like this INSERT INTO InvoiceDetail (LegacyId,InvoiceId,DetailTypeId,Fee,FeeTax,Investigatorid,SalespersonId,CreateDate,CreatedById,IsChargeBack,Expense,RepoAgentId,PayeeName,ExpensePaymentId,AdjustDetailId) VALUES(1,1,2,1500.0000,0.0000,163,1002,'11/30/2001 12:00:00 AM',1116,0,550.0000,850,NULL,@ExpensePay1,NULL); DECLARE @InvDetail1 INT; SET @InvDetail1 = (SELECT @@IDENTITY); This query is generated for only 110K rows. It takes 30 minutes for all of these query's to execute I checked the query plan and the largest % nodes are A Clustered Index Insert at 57% query cost which has a long xml that I don't want to post. A Table Spool which is 38% query cost <RelOp AvgRowSize="35" EstimateCPU="5.01038E-05" EstimateIO="0" EstimateRebinds="0" EstimateRewinds="0" EstimateRows="1" LogicalOp="Eager Spool" NodeId="80" Parallel="false" PhysicalOp="Table Spool" EstimatedTotalSubtreeCost="0.0466109"> <OutputList> <ColumnReference Database="[SkipPro]" Schema="[dbo]" Table="[InvoiceDetail]" Column="InvoiceId" /> <ColumnReference Database="[SkipPro]" Schema="[dbo]" Table="[InvoiceDetail]" Column="InvestigatorId" /> <ColumnReference Column="Expr1054" /> <ColumnReference Column="Expr1055" /> </OutputList> <Spool PrimaryNodeId="3" /> </RelOp> So my question is what is there that I can do to improve the speed of this thing? I already run ALTER TABLE TABLENAME NOCHECK CONSTRAINTS ALL Before the queries and then ALTER TABLE TABLENAME NOCHECK CONSTRAINTS ALL after the queries. And that didn't shave off hardly anything off of the time. Know I am running these queries in a .NET application that uses a SqlCommand object to send the query. I then tried to output the sql commands to a file and then execute it using sqlcmd, but I wasn't getting any updates on how it was doing, so I gave up on that. Any ideas or hints or help?

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• PostgreSQL - Error: SQL state: XX000.

  - by rob

  I have a table in Postgres that looks like this: CREATE TABLE "Population" ( "Id" bigint NOT NULL DEFAULT nextval('"population_Id_seq"'::regclass), "Name" character varying(255) NOT NULL, "Description" character varying(1024), "IsVisible" boolean NOT NULL CONSTRAINT "pk_Population" PRIMARY KEY ("Id") ) WITH ( OIDS=FALSE ); And a select function that looks like this: CREATE OR REPLACE FUNCTION "Population_SelectAll"() RETURNS SETOF "Population" AS $BODY$select "Id", "Name", "Description", "IsVisible" from "Population"; $BODY$ LANGUAGE 'sql' STABLE COST 100 Calling the select function returns all the rows in the table as expected. I have a need to add a couple of columns to the table (both of which are foreign keys to other tables in the database). This gives me a new table def as follows: CREATE TABLE "Population" ( "Id" bigint NOT NULL DEFAULT nextval('"population_Id_seq"'::regclass), "Name" character varying(255) NOT NULL, "Description" character varying(1024), "IsVisible" boolean NOT NULL, "DefaultSpeciesId" bigint NOT NULL, "DefaultEcotypeId" bigint NOT NULL, CONSTRAINT "pk_Population" PRIMARY KEY ("Id"), CONSTRAINT "fk_Population_DefaultEcotypeId" FOREIGN KEY ("DefaultEcotypeId") REFERENCES "Ecotype" ("Id") MATCH SIMPLE ON UPDATE NO ACTION ON DELETE NO ACTION, CONSTRAINT "fk_Population_DefaultSpeciesId" FOREIGN KEY ("DefaultSpeciesId") REFERENCES "Species" ("Id") MATCH SIMPLE ON UPDATE NO ACTION ON DELETE NO ACTION ) WITH ( OIDS=FALSE ); and function: CREATE OR REPLACE FUNCTION "Population_SelectAll"() RETURNS SETOF "Population" AS $BODY$select "Id", "Name", "Description", "IsVisible", "DefaultSpeciesId", "DefaultEcotypeId" from "Population"; $BODY$ LANGUAGE 'sql' STABLE COST 100 ROWS 1000; Calling the function after these changes results in the following error message: ERROR: could not find attribute 11 in subquery targetlist SQL state: XX000 What is causing this error and how do I fix it? I have tried to drop and recreate the columns and function - but the same error occurs. Platform is PostgreSQL 8.4 running on Windows Server. Thanks.

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• Java: Combine 2 List <String[]>

  - by battousai622

  I have two List of array string. I want to be able to create a New List (newList) by combining the 2 lists. But it must meet these 3 conditions: 1) Copy the contents of store_inventory into newList. 2) Then if the item names in store_inventory & new_acquisitions match, just add the two quantities together and change it in newList. 3) If new_acquisitions has a new item that does not exist in store_inventory, then add it to the newList. The titles for the CSV list are: Item Name, Quantity, Cost, Price. The List contains an string[] of item name, quantity, cost and price for each row. CSVReader from = new CSVReader(new FileReader("/test/new_acquisitions.csv")); List <String[]> acquisitions = from.readAll(); CSVReader to = new CSVReader(new FileReader("/test/store_inventory.csv")); List <String[]> inventory = to.readAll(); List <String[]> newList; Any code to get me started would be great! =] this is what i have so far... for (int i = 0; i < acquisitions.size(); i++) { temp1 = acquisitions.get(i); for (int j = 1; j < inventory.size(); j++) { temp2 = inventory.get(j); if (temp1[0].equals(temp2[0])) { //if match found... do something? //break out of loop } } //if new item found... do something? }

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• Concurrent WCF calls via shared channel

  - by Kent Boogaart

  I have a web tier that forwards calls onto an application tier. The web tier uses a shared, cached channel to do so. The application tier services in question are stateless and have concurrency enabled. But they are not being called concurrently. If I alter the web tier to create a new channel on every call, then I do get concurrent calls onto the application tier. But I wanted to avoid that cost since it is functionally unnecessary for my scenario. I have no session state, and nor do I need to re-authenticate the caller each time. I understand that the creation of the channel factory is far more expensive than than the creation of the channels, but it is still a cost I'd like to avoid if possible. I found this article on MSDN that states: While channels and clients created by the channels are thread-safe, they might not support writing more than one message to the wire concurrently. If you are sending large messages, particularly if streaming, the send operation might block waiting for another send to complete. Firstly, I'm not sending large messages (just a lot of small ones since I'm doing load testing) but am still seeing the blocking behavior. Secondly, this is rather open-ended and unhelpful documentation. It says they "might not" support writing more than one message but doesn't explain the scenarios under which they would support concurrent messages. Can anyone shed some light on this?

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