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• Web application interacts bi-directional with server program?

  - by Roelof Berkepeis

  I want to write a web application to play chess against the engine Crafty. I'm not new to PHP and javascript, but must learn how to interact with a server process : how can a web application and/or (jQuery) ajax interact bi-directionally with a (linux) program running on the server? At this moment i am developing on (Apache) local host. Crafty is installed on my Ubuntu PC. This well-known chess engine has no GUI, it runs in terminal by the command $ /usr/games/crafty and so you can play chess against it and even see it's calculations. I can make Crafty run by PHP, using the functions proc_open() or exec(), and most documentation i found states that the output stream should be a file .. But i think i don't want such setup, because then the webpage should be constanty polling that file (eg. by ajax) to see if some new data was appended, right? How can Crafty talk to the web page directly, saying "i have calculated another variation" or "i have decided a move" etc, then display this info on the web page and let the user give some counter move, just like in terminal. Isn't it possible to use some session / stream / listener? I have no clue at all, can anybody point me in a right direction?

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• AI agents with FSM: a question regarding this

  - by Prog

  Finite State Machines implemented with the State design pattern are a common way to design AI agents. I am familiar with the State design pattern and know how to implement it. However I have a question regarding how this is used in games to design AI agents. Please consider a class Monster that represents an AI agent. Simplified it looks like this: class Monster{ State state; // other fields omitted public void update(){ // called every game-loop cycle state.execute(this); } public void setState(State state){ this.state = state; } // irrelevant stuff omitted } There are several State subclasses that implement execute() differently. So far classic State pattern. Here's my question: AI agents are subject to environmental effects and other objects communicating with them. For example an AI agent might tell another AI agent to attack (i.e. agent.attack()). Or a fireball might tell an AI agent to fall down. This means that the agent must have methods such as attack() and fallDown(), or commonly some message receiving mechanism to understand such messages. My question is divided to two parts: 1- Please say if this is correct: With an FSM, the current State of the agent should be the one taking care of such method calls - i.e. the agent delegates to the current state upon every event. Correct? Or wrong? 2- If correct, than how is this done? Are all states obligated by their superclass) to implement methods such as attack(), fallDown() etc., so the agent can always delegate to them on almost every event? Or is it done in some other way?

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• Should I use a config file or database for storing business rules?

  - by foiseworth

  I have recently been reading The Pragmatic Programmer which states that: Details mess up our pristine code—especially if they change frequently. Every time we have to go in and change the code to accommodate some change in business logic, or in the law, or in management's personal tastes of the day, we run the risk of breaking the system—of introducing a new bug. Hunt, Andrew; Thomas, David (1999-10-20). The Pragmatic Programmer: From Journeyman to Master (Kindle Locations 2651-2653). Pearson Education (USA). Kindle Edition. I am currently programming a web app that has some models that have properties that can only be from a set of values, e.g. (not actual example as the web app data confidential): light-type = sphere / cube / cylinder The light type can only be the above three values but according to TPP I should always code as if they could change and place their values in a config file. As there are several incidents of this throughout the app, my question is: Should I store possibly values like these in: a config file: 'light-types' = array(sphere, cube, cylinder), 'other-type' = value, 'etc = etc-value a single table in a database with one line for each config item a database with a table for each config item (e.g. table: light_types; columns: id, name) some other way? Many thanks for any assistance / expertise offered.

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• ISO 12207 - testing being only validation activity? [closed]

  - by user970696

  Possible Duplicate: How come verification does not include actual testing? ISO norm 12207 states that testing is only validation activity, while all static inspections are verification (that requirement, code.. is complete, correct..). I did found some articles saying its not correct but you know, it is not "official". I would like to understand because there are two different concepts (in books & articles): 1) Verification is all testing except for UAT (because only user can really validate the use). E.g. here OR 2) Verification is everything but testing. All testing is validation. E.g. here Definitions are mostly the same, as Sommerville's: The aim of verification is to check that the software meets its stated functional and non-functional requirements. Validation, however, is a more general process. The aim of validation is to ensure that the software meets the customer’s expectations. It goes beyond simply checking conformance with the specification to demonstrating that the software does what the customer expects it to do It is really bugging me because I tend to agree that functional testing done on a product (SIT) is still verification because I just follow the requirements. But ISO does not agree..

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• Complex shading using one single (small) texture

  - by teodron

  Recently I stumbled upon a demo reel in UDK about how one can attain beautiful results using just one (rather tiny) texture that's being sent to the shader pipeline. The famous link is this one. Basically, the author states that they've used just one texture and give a snapshot of the technique here. I see that every RGBA channel contains different grayscale information.. and that info could be used to inside a shader to obtain a colour blended output. The problem is that the reel displays a fairly complex scene. To top that, the author even makes use of a normal map. How did they manage to fit a normal map in an already cluttered texture? It makes sense to have a half-space normal map by using only RG from an RGB texture, but what about the rest of the information? Since it was proven to be possible, could someone please explain how it was done (the big picture, not the dirty details!)!? Here's the texture being used. Click to see in full size.

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• What are some good tips for a developer trying to design a scalable MySQL database?

  - by CFL_Jeff

  As the question states, I am a developer, not a DBA. I have experience with designing good ER schemas and am fairly knowledgeable about normalization and good schema design. I have also worked with data warehouses that use dimensional modeling with fact tables and dim tables. However, all of the database-driven applications I've developed at previous jobs have been internal applications on the company's intranet, never receiving "real-world traffic". Furthermore, at previous jobs, I have always had a DBA or someone who knew much more than me about these things. At this new job I just started, I've been asked to develop a public-facing application with a MySQL backend and the data stored by this application is expected to grow very rapidly. Oh, and we don't have a DBA. Well, I guess I am the DBA. ;) As far as designing a database to be scalable, I don't even know where to start. Does anyone have any good tips or know of any good educational materials for a developer who has been sort of shoved into a DBA/database designer role and has been tasked with designing a scalable database to support an application like this? Have any other developers been through this sort of thing? What did you do to quickly become good at this role? I've found some good slides on the subject here but it's hard to glean details from slides. Wish I could've attended that guy's talk. I also found a good blog entry called 5 Ways to Boost MySQL Scalability which had some good information, though some of it was over my head. tl;dr I just want to make sure the database doesn't have to be completely redesigned when it scales up, and I'm looking for tips to get it right the first time. The answer I'm looking for is a "list of things every developer should know about making a scalable MySQL database so your application doesn't perform like crap when the data gets huge".

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• Is white the best base color to start with when planning to shade sprites within Unity?

  - by SpartanDonut

  I'm looking into prototyping a game in Unity which will consist of solid square sprites / tiles. I figure I can represent different types of objects with different colors for each of the tiles in the game. I figure that I can import a single square sprite and shade it appropriately in Unity as opposed to imported squares of many different colors. My experience with adjusting the hue and saturation within Photoshop shows that white is not an easy color to change as things that are white often stay white. My testing in Unity shows that I can change the "color" of a sprite to anything other than white and the sprite is seemingly shaded appropriately, despite what I would have thought given my Photoshop experience. Since white objects do seem to take on the appropriate color shading when changed within Unity my gut tells me that this is the best base color to begin with, meaning that I can import a single white square sprite and simply adjust the color to represent different objects and object states. Is a white sprite actually the best color sprite to begin with and why does something like this work in Unity as opposed to adjusting the hue and saturation within Photoshop?

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• Back in Town and Ready for New Beginnings

  - by MOSSLover

  Originally posted on: http://geekswithblogs.net/MOSSLover/archive/2013/11/03/back-in-town-and-ready-for-new-beginnings.aspxI just took a super long trip that lasted from September 27th until today.  I flew into St. Louis and then rented a car and drove over 12,000 miles.  I just dropped the rental off last night.  I went to a ton of states, did a lot of really cool things, saw a lot of really cool people, and bought a ton of beer.  I made some decisions, but this post isn't really about my decisions.  It's more about the question that everyone has been asking, "Where am I going to work?".So here's the answer...BlueMetal Architects as a Senior SharePoint Engineer.  Here is their website: http://www.bluemetal.com/.  I basically start tomorrow.  I didn't want to post anything super early, because I didn't want to jinx things.  I am really excited.  Now that I'm back I'm hoping that things will start to turn around for me.  I look forward to the future.

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• Material System

  - by Towelie

  I'm designing Material/Shader System (target API DX10+ and may be OpenGL3+, now only DX10). I know, there was a lot of topics about this, but i can't find what i need. I don't want to do some kind of compilation/parsing scripts in real-time. So there some artist-created material, written at some analog of CG. After it compiled to hlsl code and after to final shader. Also there are some hard-coded ConstantBuffers, like cbuffer EveryFrameChanging { float4x4 matView; float time; float delta; } And shader use shared constant buffers to get parameters. For each mesh in the scene, getting needs and what it can give (normals, binormals etc.) and finding corresponding permutation of shader or calculating missing parts. Also, during build calculating render states and the permutations or hash for this shader which later will be used for sorting or even giving the ID from 0 to ShaderCount w/o gaps to it for sorting. FinalShader have only 1 technique and one pass. After it for each Mesh setting some shader and it's good to render. some pseudo code SetConstantBuffer(ConstantBuffer::PerFrame); foreach (shader in FinalShaders) SetConstantBuffer(ConstantBuffer::PerShader, shader); SetRenderState(shader); foreach (mesh in shader.GetAllMeshes) SetConstantBuffer(ConstantBuffer::PerMesh, mesh); SetBuffers(mesh); Draw(); class FinalShader { public: UUID m_ID; RenderState m_RenderState; CBufferBindings m_BufferBindings; } But i have no idea how to create this CG language and do i really need it?

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• Fresh install of 64 bit 12.04 over 32 bit 11.10 alongside Windows 7

  - by Pareen

  I currently have Ubuntu 11.10 32 bit and Windows 7 dual boot in separate partitions. I am trying to do a fresh install of Ubuntu 12.04 64 bit (mistakenly installed the 32 bit 11.10 a little while ago.. I need a 64 bit version to support AOSP build) OVER my the exisiting 11.10 partition. I have referenced How to Install fresh 12.04 install to a PC with dual booting Windows 7 & Ubuntu11.10?, as well as other posts on using the Live CD to do a fresh install. However, the problem I am experiencing is when I bring up the install screen, it says the following: This computer has multiple operating systems on it. What would you like to do. (3 options) Install Ubuntu 12.04 alongside them Replace all with Ubuntu 12.04 (Warning, this will delete files across ALL operating systems) Something else (you can create or resize partitions yourself) This is different from what is in other posts, as mine states that there are "multiple O.Ses" and doesnt individually allow me to replace the Ubuntu 11.10. I don't want to replace ALL O.S.es: I need to preserve Windows 7 and am only trying to replace the old Ubuntu 11.10 partition with the new 12.04 64 bit. I did have Ubuntu installed via Wubi (I believe it was 10.04) prior to putting 11.10 in a separate partition, but I have removed it via Add/Remove programs in Windows. I was wondering how to go about doing this... Should I use the "Something else" option to bring up the partition manager, and just assign my existing 11.10 partition with root mount point + swap space. Will this do the same thing by overwriting with fresh 12.04 install?? I appreciate all your help.

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• How can I get my monitor's maximum resolution without the proprietary AMD graphic driver installed?

  - by Venki

  I am using Ubuntu 14.04. I have an AMD Radeon 5570 HD graphic card. Actually, the default open source REDWOOD drivers aren't allowing me to choose my monitor's maximum screen resolution(which is 1366 x 768). I just have two resolutions displayed which are 1024x768 and 800x600 . If I give the command : xrandr -s 1366x768 then the output is: Size 1366x768 not found in available modes So just for the sake of getting 1366x768 resolution I am forced to install the proprietary graphic driver that AMD gives me from its site. But if I install it(which itself is quite a problem-prone process), I undergo a lot of 'inconvenience'. Sometimes after an OS update, the driver crashes unity. Then I will have to uninstall that driver from a tty and google around for a solution. Also I encounter screen tearing problems occasionally. In addition I also cant see my login screen(See this question which states this particular problem). The main problem is AMD does not update its driver as quick as Ubuntu updates its OS. This is quite irritating. So, I want the maximum resolution(and performance) that my graphics card and monitor can give me without installing the 'problematic' proprietary graphic card driver that AMD gives. Is this possible? Suggestions please. Thanks in advance. PS :- More system specs details:- Intel i3 2100 processor AMD P8H61-M PLUS2 motherboard AMD Radeon 5570 HD graphic card DELL monitor (BTW, Thank you for reading through my elaborate description!)

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• How to develop a Windows 8 app in 30 days!

  - by Scott Spradlin

  Begin your 30-day journey to create a Windows Store style app. Sign up to get started and receive: Insider tips and tricks on Windows 8 application development. Personal on-the-phone access to a Windows 8 architect*. An exclusive one-on-one Windows Store design consultation*. An opportunity to get expert help from a Microsoft Services Engineer at an App Excellence Lab. Sign up today and get started. Your new Windows 8 app could be mere days away. * Offer good only to legal residents in the 50 United States & D.C., age 18 or older to hobbyists, professionals or developers in the field of software tech who sign up for building a Windows 8 application on www.generationapp.com. Offer limited to 250 design consultations per month and 500 technical review consultations per month, on a first come first served basis. Limit of one session of each offer type per person. This offer is non-transferable and cannot be combined with any other offer. This offer ends when supplies are exhausted, and is not redeemable for cash.

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• design an extendible and pluggable business logic flow handler in php

  - by Broncha

  I am working on a project where I need to allow a pluggable way to inject business processes in the normal data flow. eg There is an ordering system. The standard flow of the application is A consumer orders an item. Pays for it and card is authorized. Admin captures the payment. Order is marked as complete and item is shipped. But this process may vary (extra steps in between) for different clients. Say a client would need to validate the location of the consumer before he is presented with a credit card form, OR his policies might require some other processes in between. I am thinking of using State Pattern for processing orders, saving the current state of the order in database, and initializing the state of order from the saved state. I would also need some mechanism, where a small plugin would be able to inject business specific states in the state machine. Am I thinking the right way? Are there already implemented patterns for this kind of situation? I am working with Codeigniter and basically this would mean for me, to redirect to proper controller according to the current state of the order. Like, if the state of the order is unconfirmed then redirect the user to details page and then change the state to pending. If some client would need to do some validation, then register an intermediate state between unconfirmed and pending Please suggest.

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• Stop Time Sync Between Host and Guest - VirtualBox

  - by KoopaTroopa

  So I've been googling and I've tried the following commands. I want to stop the virtual machine from having the correct time and just to stick with what time it last recorded. The host operating system is Ubuntu 12.04 and the guest is Windows XP. I've turned time syncing off in XP so it won't do that when I connect to the Internet. However it does appear to take the time from ubuntu and set it as it's own. VBoxManage setextradata XP11 “VBoxInternal/TM/WarpDrivePercentage” 200 vboxmanage setextradata XP11 "VBoxInternal/Devices/VMMDev/0/Config/GetHostTimeDisabled" "1" Both commands haven't work as the time is always set to the exact same as Ubuntu's. I've located the extradata entry in the virtualbox XML file. It states both changes that the commands above are set to make. But of course it still hasn't stopped updating the time. <ExtraData> <ExtraDataItem name="GUI/LastGuestSizeHint" value="1152,864"/> <ExtraDataItem name="GUI/LastNormalWindowPosition" value="74,52,1152,911"/> <ExtraDataItem name="VBoxInternal/Devices/VMMDev/0/Config/GetHostTimeDisabled" value="1"/> <ExtraDataItem name="&#x201C;VBoxInternal/TM/WarpDrivePercentage&#x201D;" value="200"/> </ExtraData>

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• Web Service Standard Complexity

  Are we over-standardizing web services and hindering their adoption? No, and in fact I feel that it is helping its adoption in the modern corporate world. Standards, although they can be daunting and tedious, provide a universal framework to which we all can operate in and around. These frameworks provide a common interface for all of to use when interaction with various computing environments so that data can be transfer freely.  Standards are protocols in which computers communicate with one another. If we take this to the living world, the united nations hires interprets for all each countries dignitaries so that they can understand what other countries are talking about. Imagine if the president of the United States wanted to talk to the ruler of China. How would these to communicate? The interpreter would translate data back and forth acting as in intermediary using both standard American English and Chinese. Without knowing the standards in either language no one would be able to communicate. Even though we work within the framework of standards does not mean that we are stuck with these standards. As technology evolves all standards will be out of touch, and when this occurs standards need to be refactored or replaced with new standards that are current with the technology at that time. How else are we as developers and the technology going to grow? What do you guys think?

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• Can observer pattern be represented by cars and traffic lights?

  - by eeerahul

  I wanted to verify with all of you, if I have a correct Observer Pattern analogy. The scenario is as follows: Consider, at a junction, there is a traffic signal, having red, yellow and green lights respectively. There are vehicles facing the traffic signal post. When it shows red, the vehicles stop, when it shows green, the vehicles move on. In case, it is yellow, the driver must decide whether to go or to stop, depending on whether he/she has crossed the stop line or not. At the same time, there are vehicles that do not care about the signal. They would do as they like. The similarities are that, the Traffic Signal happens to be the subject, notifying its states by glowing the appropriate lights. Those looking at it and following the signal are the ones subscribed to it, and behave according to the state of the subject. Those who do not care about it, are sort-of un-subscribed from the traffic signal. Please tell me, if you think this is a correct analogy or not?

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• Ubuntu 12.04 + Bluetooth problems with maintaining connection

  - by ifndefx

  I have an Apple Wireless Mouse, Apple Wireless Keyboard, Apple Wireless Trackpad, and a pair of headphones. All of these connect to the computer via a Bluetooth dongle. After several hours I've managed to get the devices paired (all except the headphones) with the computer. However, I'm facing a problem where a connection can't be maintained even with one device. I first started with the gnome bluetooth applet, this couldn't even pick up devices, so I installed blueman, and this at least detected the devices but it couldn't keep the connection going. Then i read somewhere to get hidd installed and use the command line using the mac address of the device (which I got from blueman) and this worked really well, the connection was stable, but there's still a couple of issues that I need help with: If I am to use hidd I need to execute this via terminal, which means for the keyboard and the mouse I need to have two of each. This doesn't make sense. I need the bluetooth daemon to have started with the devices picked up a lot earlier, and especially at grub bootloader. The mouse and the trackpad both work if i use hidd, however, I cannot get the right mouse to work nor the scroll wheel to work. The headphones don't work period, they don't work with any of the bluetooth applets, and with hidd either. When I use blueman aplet, it attempts to pair and states 'Authentication Rejected". The headphone is Phillips SHB9100. If someone can help me with this, I would be grateful.

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• PyQt application architecture

  - by L. De Leo

  I'm trying to give a sound structure to a PyQt application that implements a card game. So far I have the following classes: Ui_Game: this describes the ui of course and is responsible of reacting to the events emitted by my CardWidget instances MainController: this is responsible for managing the whole application: setup and all the subsequent states of the application (like starting a new hand, displaying the notification of state changes on the ui or ending the game) GameEngine: this is a set of classes that implement the whole game logic Now, the way I concretely coded this in Python is the following: class CardWidget(QtGui.QLabel): def __init__(self, filename, *args, **kwargs): QtGui.QLabel.__init__(self, *args, **kwargs) self.setPixmap(QtGui.QPixmap(':/res/res/' + filename)) def mouseReleaseEvent(self, ev): self.emit(QtCore.SIGNAL('card_clicked'), self) class Ui_Game(QtGui.QWidget): def __init__(self, window, *args, **kwargs): QtGui.QWidget.__init__(self, *args, **kwargs) self.setupUi(window) self.controller = None def place_card(self, card): cards_on_table = self.played_cards.count() + 1 print cards_on_table if cards_on_table <= 2: self.played_cards.addWidget(card) if cards_on_table == 2: self.controller.play_hand() class MainController(object): def __init__(self): self.app = QtGui.QApplication(sys.argv) self.window = QtGui.QMainWindow() self.ui = Ui_Game(self.window) self.ui.controller = self self.game_setup() Is there a better way other than injecting the controller into the Ui_Game class in the Ui_Game.controller? Or am I totally off-road?

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• UDK - How to make sure a PhysicalMaterial mask actually works?

  - by tomacmuni

  Hello, I have been reading the documentation for UDK about physical materials and masks. I have my 1bit BMP mask, and the two physical material assets I want to shoot off in the black and white channels. I have applied my material to both a rigid body and to a skeletal mesh and neither apparently uses the mask. If I assign a regular physical material (one that doesn't use a mask) then it will work fine, but this defeats the point because it gives only one hit reaction. In the documentation it states that it is possible to extend a class on which we want to use a physical material based on the KActor class's usage. How to do that? Here is the quote: "The following properties [ie, ImpactEffect - Particle system to spawn at the point of impact + ImpactSound - Sound to play when an impact occurs] allow you to attach sounds and effects to physical collisions. These only work on classes which support them, which at the moment is only KActor. By looking at the implementation in KActor though, you can add this functionality to other classes (or you can subclass KActor)." Essentially, how to make sure a PhysicalMaterial mask actually works? What code could be added to a skeletal mesh class perhaps, to get it going? Any help appreciated.

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• Location-Based redirection and duplication in sub-directories affecting SEO

  - by Joshua

  I currently own the website www.xyz.com. The website has a sub-directory for each of the 3 target countries: .../en-US/ (United States), .../es-MX/ (Mexico), and .../es-DO/ (Dominican Republic). I have two main questions about this setup: Currently, the main domain/root (xyz.com) contains a blank index.php file, but I would like for a user to be redirected to one of the sub-directories based on their regional location. What is the best way to accomplish this? I have looked at using browser language-based redirection, but how would I know whether to direct a user to the MX or DO site if the browser language is set to spanish? Is there a way to detect a user's geographic location? Also, the 3 websites are practically identical except they all have 3 unique color schemes and the US site is in english while the MX and DO sites are in spanish. My problem is that I believe GoogleBot is penalizing/banning my site because the spanish text on the MX and DO pages are nearly identical and are thus marked as duplicates/spam. Is there a way to avoid this?

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• How to force ADF to speak your language (or any common language)

  - by Blueberry Coder

  When I started working for Oracle, one of the first tasks I was given was to contribute some content to a great ADF course Frank and Chris are building. Among other things, they asked me to work on a module about Internationalization. While doing research work, I unearthed a little gem I had overlooked all those years. JDeveloper, as you may know, speaks your language - as long as your language is English, that is. Oracle ADF, on the other hand, is a citizen of the world. It is available in more than 25 different languages. But while this is a wonderful feature for end users, it is rather cumbersome for developers. Why is that? Have you ever tried to search the OTN forums for a solution with a non-English error message as your query? I have, once. But how can you force ADF to use English for its logging operations? Playing with your system settings will not help, unfortunately. By default, ADF will output its error messages in the selected locale for the operating system account the application server runs on. The only way to change this behavior is to pass initialization parameters to the JVM used by the application server. It is even possible to specify the language and country/region separately. In the example below, we choose English and the United States respectively. -Duser.language=en -Duser.country=US In the case of WebLogic Server, it is possible to add such parameters in setDomainEnv.sh (or .cmd) to apply the settings to all the managed servers present on a node. In the coming weeks, I will write a few posts about other internationalization issues. Is there anything you would like me to cover? Let me know in the comments.

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• Change the Log Level of Node Manager.

  - by adejuanc

  This is useful to troubleshoot issues related to Node Manager, such as problems starting a Managed Server or reasons a server could be (re)started. To change the Log Level of Node Manager, you need to edit the nodemanager.properties file. This is usually located at: <MIDDLEWARE_HOME>/wlserver_10.3/common/nodemanager What you need to modify is property: ...LogLevel=INFO... Information about the appropriate values for this property is available in the Node Manager Documentation at 10.3 WebLogic Documentation (and in further releases) which states: LogLevel: Severity level of logging used for the Node Manager log. Node Manager uses the same logging levels as WebLogic Server. Default value: INFO However, this is incorrect. WLS has its own implementation of LogLevel, but Node Manager uses the standard Log Level from the java.util.logging.Level class. Therefore, the possible values for Node Manager LogLevel, in descending order are: SEVERE (highest value) WARNING INFO CONFIG FINE FINER FINEST (lowest value) The highest value provides only messages at the severe level. The warning level provides warning messages and severe messages, and so on. Besides those levels, ALL and OFF are also accepted. For example, if you only want Severe messages to be logged, select SEVERE. If you need the most detailed tracing available, select FINEST. For more information on what it will log at each level, please read the Java SE API for LoggingLevel.

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• State Changes in a Component Based Architecture [closed]

  - by Maxem

  I'm currently working on a game and using the naive component based architecture thingie (Entities are a bag of components, entity.Update() calls Update on each updateable component), while the addition of new features is really simple, it makes a few things really difficult: a) multithreading / currency b) networking c) unit testing. Multithreading / Concurrency is difficult because I basically have to do poor mans concurrency (running the entity updates in separate threads while locking only stuff that crashes (like lists) and ignoring the staleness of read state (some states are already updated, others aren't)) Networking: There are no explicit state changes that I could efficiently push over the net. Unit testing: All updates may or may not conflict, so automated testing is at least awkward. I was thinking about these issues a bit and would like your input on these changes / idea: Switch from the naive cba to a cba with sub systems that work on lists of components Make all state changes explicit Combine 1 and 2 :p Example world update: statePostProcessing.Wait() // ensure that post processing has finished Apply(postProcessedState) state = new StateBag() Concurrently( () => LifeCycleSubSystem.Update(state), // populates the state bag () => MovementSubSystem.Update(state), // populates the state bag .... }) statePostProcessing = Future(() => PostProcess(state)) statePostProcessing.Start() // Tick is finished, the post processing happens in the background So basically the changes are (consistently) based on the data for the last tick; the post processing can a) generate network packages and b) fix conflicts / remove useless changes (example: entity has been destroyed - ignore movement etc.). EDIT: To clarify the granularity of the state changes: If I save these post processed state bags and apply them to an empty world, I see exactly what has happened in the game these state bags originated from - "Free" replay capability. EDIT2: I guess I should have used the term Event instead of State Change and point out that I kind of want to use the Event Sourcing pattern

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• Offsite Backup

  - by Grant Fritchey

  There was a recent weather event in the United States that seriously impacted our power grid and our physical well being. Lots of businesses found that they couldn’t get to their building or that their building was gone. Many of them got to do a full test of their disaster recovery processes. A big part of DR is having the ability to get yourself back online in a different location. Now, most of us are not going to be paying for multiple sites, but, we need the ability to move to one if needed. The best thing you can to start to set this up is have an off-site backup. Want an easy way to automate that? I mean, yeah, you can go to tape or to a portable drive (much more likely these days) and then carry that home, but we’ve all got access to offsite storage these days, SkyDrive, DropBox, S3, etc. How about just backing up to there? I agree. Great idea. That’s why Red Gate is setting up some methods around it. Want to take part in the early access program? Go here and try it out.

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• How to choose between Tell don't Ask and Command Query Separation?

  - by Dakotah North

  The principle Tell Don't Ask says: you should endeavor to tell objects what you want them to do; do not ask them questions about their state, make a decision, and then tell them what to do. The problem is that, as the caller, you should not be making decisions based on the state of the called object that result in you then changing the state of the object. The logic you are implementing is probably the called object’s responsibility, not yours. For you to make decisions outside the object violates its encapsulation. A simple example of "Tell, don't Ask" is Widget w = ...; if (w.getParent() != null) { Panel parent = w.getParent(); parent.remove(w); } and the tell version is ... Widget w = ...; w.removeFromParent(); But what if I need to know the result from the removeFromParent method? My first reaction was just to change the removeFromParent to return a boolean denoting if the parent was removed or not. But then I came across Command Query Separation Pattern which says NOT to do this. It states that every method should either be a command that performs an action, or a query that returns data to the caller, but not both. In other words, asking a question should not change the answer. More formally, methods should return a value only if they are referentially transparent and hence possess no side effects. Are these two really at odds with each other and how do I choose between the two? Do I go with the Pragmatic Programmer or Bertrand Meyer on this?

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