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• Best way to go for simple online multi-player games?

  - by Mr_CryptoPrime

  I want to create a trivia game for my website. The graphic design does not have to be too fancy, probably no more advanced than a typical flash game. It needs to be secure because I want users to be able to play for real money. It also needs to run fast so users don't spend their time frustrated with game freezing. Compatibility, as with almost all online products, is key because of the large target market. I am most acquainted with Java programming, but I don't want to do it in Java if there is something much better. I am assuming I will have to utilize a variety of different languages in order for everything to come together. If someone could point out the main structure of everything so I could get a good start that would be great! 1) Language choice for simple secure online multiplayer games? 2) Perhaps use a database like MySQL, stored on a secure server for the trivia questions? 3) Free educational resources and even simpler projects to practice? Any ideas or suggestions would be helpful...Thanks!

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• Creating new games on Android and/or iPhone

  - by James Clifton

  I have a succesfull facebook poker game that is running very nicely, now some people have asked if I can port this to other platforms - mainly mobile devices (and I have been asked to make a tablet version, do I really need a seperate version?) I am currently a PHP programmer (and game designer) and I simply dont' have the time to learn Android and other languages - so I have decided to pay third parties to program them (if viable). The information I need to know is what programming language is needed for the following four devices - Android mobile phone, iPhone, iPad and tablets? Can they all run off a central sql database? If they can't then i'm not interested :( Do any of these run FLASH? Have I covered all my main bases here? For example if a person programs for a ANDROID mobile phone is that to much differant to an ANDROID tablet? They will have slightly differant graphics (because the tablet has a greater screen area might as well use it) but do they need to be started from scratch? Same goes for iPhone/iPad, do they really need to be programmed differantly if the only differance is the graphics?

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• OBIEE 11.1.1.6.5 Bundle Patch released Oct 2012

  - by user554629

  October  2012 OBIEE 11.1.1.6.5 Bundle Patch released Bundle patches are collection of controlled, well tested critical bug fixes for a specific product  which may include security contents and occasionally minor enhancements. These are cumulative in nature meaning the latest bundle patch in a particular series would include the contents of the previous bundle patches released.  A suite bundle patch is an aggregation of multiple product  bundle patches that are part of a product suite. For OBIEE on 11.1.1.6.0, we plan to run a monthly bundle patch cadence. 11.1.1.6.5 bundle patch- available for download from  My Oracle Support . - is cumulative, so it includes everything from previous updates- available for supported platforms ( Windows, Linux, Solaris, AIX, HPUX-IA ) Navigate to https://support.oracle.com and login- Knowledge Base tab  Select a product line [ Business Intelligence ]  Select a Task [ Patching and Maintenance ]  Click Search- Oct 23, 2012, OBIEE 11g: Required and Recommended Patches and Patch Sets, ID 1488475.1- 11.1.1.6.5 Published 19th October 2012 Note: The 11.1.1.6 versions on top of 11.1.1.6.0 are not upgrades, they are opatch fixes.  This is not an upgrade process like from OBIEE 10g to 11g, or from OBIEE 11.1.1.5 to 11.1.1.6.  It is much safer than applying any one-off fixes, which are not regression tested.  You will be more successful using 11.1.1.6.5.  

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• XboxMP Helps You Find Multiplayer Games for the Xbox

  - by Jason Fitzpatrick

  Searching for the perfect versus or cooperative Xbox multiplayer game can be challenging–the game publisher says it plays four but what exactly does that mean? XboxMP catalogs games with detailed breakdowns of what the multiplayer experience actually entails. You can search first generation Xbox games, Xbox 360 games, and Xbox Live Arcade games with a variety of detailed criteria including the number of players it supports for local, system link, and online play (it may be a deal breaker, for example, that the only way to play the game with 4 players is to have two Xboxes or an Xbox live account). In addition to the multiplayer game data each game listing also includes addition information about the general game play including peripheral support and other features. Hit up the link below to check it out and, for more help finding multiplayer cooperative games, make sure to check out previously reviewed Co-Optimus. XBoxMP What Is the Purpose of the “Do Not Cover This Hole” Hole on Hard Drives? How To Log Into The Desktop, Add a Start Menu, and Disable Hot Corners in Windows 8 HTG Explains: Why You Shouldn’t Use a Task Killer On Android

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• Understanding Application binary interface (ABI)

  - by Tim

  I am trying to understand the concept of Application binary interface (ABI). From The Linux Kernel Primer: An ABI is a set of conventions that allows a linker to combine separately compiled modules into one unit without recompilation, such as calling conventions, machine interface, and operating-system interface. Among other things, an ABI defines the binary interface between these units. ... The benefits of conforming to an ABI are that it allows linking object files compiled by different compilers. From Wikipedia: an application binary interface (ABI) describes the low-level interface between an application (or any type of) program and the operating system or another application. ABIs cover details such as data type, size, and alignment; the calling convention, which controls how functions' arguments are passed and return values retrieved; the system call numbers and how an application should make system calls to the operating system; and in the case of a complete operating system ABI, the binary format of object files, program libraries and so on. I was wondering whether ABI depends on both the instruction set and the OS. Are the two all that ABI depends on? What kinds of role does ABI play in different stages of compilation: preprocessing, conversion of code from C to Assembly, conversion of code from Assembly to Machine code, and linking? From the first quote above, it seems to me that ABI is needed for only linking stage, not the other stages. Is it correct? When is ABI needed to be considered? Is ABI needed to be considered during programming in C, Assembly or other languages? If yes, how are ABI and API different? Or is it only for linker or compiler? Is ABI specified for/in machine code, Assembly language, and/or of C?

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• How to start and maintain an after-work project

  - by Sam

  I work as a full time developer. My workplace, however, is very limiting in the technologies and programming languages I can use. All of the work is done in C++. It is clear that C++ is rapidly losing (or maybe already lost) its leading position. (please don't flame me, I have years and years of C++ experience, and I love this language, I am merely stating a fact). I have a few ideas for java/android projects as well as a project I would like to implement in C#. I see this as a way for me to stay current with the job market's trends and I hope that it will help me find my next job in a more up to date area. So here's the problem, my normal workday is 10-11 hours, after finishing with the kids and house chores I get about 1-2.5 hours before I am too tired to think much less code. at that point I am going to bed frustrated, disappointed with myself for not being able to stick with my plans, and then I wake up the next morning to do it all again. I have a few hours more during the weekends but clearly I would need to do something different if I want to reach any of my goals. Is there any way for me to make better use of the time I have? Did any of you guys have a similar problem, and had succefully resolved it?

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• Engine for 2D Top-Down Physics-Based Skeletal Animation

  - by RylandAlmanza

  I just watched at the Sui Generis video, and was completely amazed. Specifically, the part where the big troll thing is beating up the player with his flail. This got me really excited, and I would like to try implementing something like this in a 2D Top-Down format. Something like this. That atloria example seems simple enough, but it's not exactly what I'm looking to make. I think atloria is using predefined animations, where as I would like to make something more physics-based like the Sui Generis engine does. So, I'm wondering what physics engines might work for something like this, and if I'd need to implement my own skeletal system, or if I could just use "joints" and such from the engine. The only experience I have in terms of physics engines is Box2D, which I've heard shouldn't be used for top-down settings, and I can think of a few reasons it wouldn't work out well. One of those reasons being gravity. In box 2D, gravity pulls towards a side of the screen (usually the bottom.) I wouldn't want my player's forearms constantly being pulled to one side. :) Also should mention that the programming language doesn't matter all that much to me. I'm currently playing with HTML5 stuff, though. :) Thanks in advance!

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• Ubuntu 12.04 Network Connection Unavailable

  - by user211315

  I recently added a EDIMAX EW-7811Un to my computer to allow wireless networking. That was working. Now after a reboot I am unable to connect to either wireless or wired network. the result of ifconfig is ifconfig eth0 Link encap:Ethernet HWaddr bc:ae:c5:46:19:6d inet6 addr: fe80::beae:c5ff:fe46:196d/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:231 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:62615 (62.6 KB) Interrupt:51 Base address:0x4000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:664 errors:0 dropped:0 overruns:0 frame:0 TX packets:664 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:52639 (52.6 KB) TX bytes:52639 (52.6 KB) tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 inet addr:10.8.0.1 P-t-P:10.8.0.2 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

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• Is ZeroMQ a good choice to make a Python app and a C# managed assembly work together?

  - by Alex Bausk

  I have a task that involves talking to a .NET-based API (namely AutoCAD) to retrieve data, send commands, and react to events. I want to separate the API operations and the proper program logic (largely already implemented in Python) by using natural tools for both: a C# DLL for the former and a Python app for the latter. To connect these two pieces, I began exchanging JSON in ZeroMQ messages. I'm at early development stages but having recently discovered that ZeroMQ does not guarantee message delivery/order, I have reservations about whether this is a feasible way to go. Right now my app is a very basic REQ/REP pair and I plan to handle reacting to events and executing different commands by adding some sort of 'recipient-function' field to my message format. The reason that I want to use ZMQ is that I might be able to scale the software into a larger, multi-user, distributed solution sometime. I am a lay programmer so I would ask for your advice about this architecture. Should I just go ahead with it and plan to deal with message reliability/ordering when problems appear? Should I consider developing some kind of a REST wrapper around ZMQ?

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• Should I build a multi-threaded system that handles events from a game and sorts them, independently, into different threads based on priority?

  - by JonathonG

  Can I build a multi-threaded system that handles events from a game and sorts them, independently, into different threads based on priority, and is it a good idea? Here's more info: I am about to begin work on porting a mid-sized game from Flash/AS3 to Java so that I can continue development with multi-threading capabilities. Here's a small bit of background about the game: The game contains numerous asynchronous activities, such as "world updating" (the game environment is constantly changing based on a set of natural laws and forces), procedural generation of terrain, NPCs, quests, items, etc., and on top of that, the effects of all of the player's interactions with his environment are programmatically calculated in real time, based on a set of constantly changing "stats" and once again, natural laws and forces. All of these things going on at once, in an asynchronous manner, seem to lend themselves to multi-threading very well. My question is: Can I build some kind of central engine that handles the "stacking" of all of these events as they are triggered, and dynamically sorts them out amongst the available threads, and would it be a good idea? As an example: Essentially, every time something happens (IE, a magic missile being generated by a spell, or a bunch of plants need to grow to their next stage), instead of just processing that task right then and adding the new object(s) to a list of managed objects, send a reference to that event to a core "event handler" that throws it into a stack of all other currently queued events, which then sorts them out and orders them according to urgency, splits them between a number of available threads for as-fast-as-possible multithreaded execution.

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• What are some practical uses of the "new" modifier in C# with respect to hiding?

  - by Joel Etherton

  A co-worker and I were looking at the behavior of the new keyword in C# as it applies to the concept of hiding. From the documentation: Use the new modifier to explicitly hide a member inherited from a base class. To hide an inherited member, declare it in the derived class using the same name, and modify it with the new modifier. We've read the documentation, and we understand what it basically does and how it does it. What we couldn't really get a handle on is why you would need to do it in the first place. The modifier has been there since 2003, and we've both been working with .Net for longer than that and it's never come up. When would this behavior be necessary in a practical sense (e.g.: as applied to a business case)? Is this a feature that has outlived its usefulness or is what it does simply uncommon enough in what we do (specifically we do web forms and MVC applications and some small factor WinForms and WPF)? In trying this keyword out and playing with it we found some behaviors that it allows that seem a little hazardous if misused. This sounds a little open-ended, but we're looking for a specific use case that can be applied to a business application that finds this particular tool useful.

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• Architecture of a "website generator" web application

  - by Resorath

  What is the most maintainable and efficient way to architect a web application who's purpose is to host and generate websites which can be customized to a certain degree? There are a lot of these style of applications in the wild that generate all kinds of sites, from sites that host World of Warcraft guilds like guildlaunch to other sites like my wedding for wedding site hosting. My question is, what is the basic architecture that these sites operate on? I imagine there are two ways of thinking about this. A central set of code that all sites on the host run against, and it acts differently based on which site was visited. In this manner, when the base code is updated all sites are updated simultaneously. Or, the code for an individual site exists in a silo, and is simply replicated to a new directory each time a site is created. When an update needs to be applied, the code is pushed out to each site silo. In my case, I am working in PHP with the CodeIgniter framework, however the answer need not be limited to this case. Which method (if any) creates a more maintainable and efficient architecture to manage this style of web application?

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• Question regarding Readability vs Processing Time

  - by Jordy

  I am creating a flowchart for a program with multiple sequential steps. Every step should be performed if the previous step is succesful. I use a c-based programming language so the lay-out would be something like this: METHOD 1: if(step_one_succeeded()) { if(step_two_succeeded()) { if(step_three_succeeded()) { //etc. etc. } } } If my program would have 15+ steps, the resulting code would be terribly unfriendly to read. So I changed my design and implemented a global errorcode that I keep passing by reference, make everything more readable. The resulting code would be something like this: METHOD 2: int _no_error = 0; step_one(_no_error); if(_no_error == 0) step_two(_no_error); if(_no_error == 0) step_three(_no_error); if(_no_error == 0) step_two(_no_error); The cyclomatic complexibility stays the same. Now let's say there are N number of steps. And let's assume that checking a condition is 1 clock long and performing a step doesn't take up time. The processing speed of Method1 can be anywhere between 1 and N. The processing speed of Method2 however is always equal to N-1. So Method1 will be faster most of the time. Which brings me to my question, is it bad practice to sacrifice time in order to make the code more readable? And why (not)?

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• Are long methods always bad?

  - by wobbily_col

  So looking around earlier I noticed some comments about long methods being bad practice. I am not sure I always agree that long methods are bad (and would like opinions from others). For example I have some Django views that do a bit of processing of the objects before sending them to the view, a long method being 350 lines of code. I have my code written so that it deals with the paramaters - sorting / filtering the queryset, then bit by bit does some processing on the objects my query has returned. So the processing is mainly conditional aggregation, that has complex enough rules it can't easily be done in the database, so I have some variables declared outside the main loop then get altered during the loop. varaible_1 = 0 variable_2 = 0 for object in queryset : if object.condition_condition_a and variable_2 > 0 : variable 1+= 1 ..... ... . more conditions to alter the variables return queryset, and context So according to the theory I should factor out all the code into smaller methods, so That I have the view method as being maximum one page long. However having worked on various code bases in the past, I sometimes find it makes the code less readable, when you need to constantly jump from one method to the next figuring out all the parts of it, while keeping the outermost method in your head. I find that having a long method that is well formatted, you can see the logic more easily, as it isn't getting hidden away in inner methods. I could factor out the code into smaller methods, but often there is is an inner loop being used for two or three things, so it would result in more complex code, or methods that don't do one thing but two or three (alternatively I could repeat inner loops for each task, but then there will be a performance hit). So is there a case that long methods are not always bad? Is there always a case for writing methods, when they will only be used in one place?

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• What to Return with Async CRUD methods C#

  - by RualStorge

  While there is a similar question focused on Java, I've been in debates with utilizing Task objects. What's the best way to handle returns on CRUD methods (and similar)? Common returns we've seen over the years are: Void (no return unless there is an exception) Boolean (True on Success, False on Failure, exception on unhandled failure) Int or GUID (Return the newly created objects Id, 0 or null on failure, exception on unhandled failure) The updated Object (exception on failure) Result Object (Object that houses the manipulated object's ID, Boolean or status field to with success or failure indicated, Exception information if there was one, etc) The concern comes into play as we've started moving over to utilizing C# 5's Async functionality, and this brought the question up of how we should handle CRUD returns large-scale. In our systems we have a little of everything in regards to what we return, we want to make these returns standardized... Now the question is what is the recommended standard? Is there even a recommended standard yet? (I realize we need to decide our standard, but typically we do so by looking at best practices, see if it makes sense for us and go from there, but here we're not finding much to work with)

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• Assuming "clean code/architecture" is there a difference in "effort" between PHP or Java/J2EE web application development?

  - by PhD

  A client asked us to estimate effort when selecting PHP as the implementation language for his next web-based application. We spent about a week exploring PHP, prototyping, testing etc., We are quite new to this language - may have hacked around it in the past but, let's go with PHP-noobs but application development experts (for the lack of a better, less flattering word :) It seems, that if we write, clean maintainable code, follow separation of concerns, enterprise architecture patters (DAOs etc.) the 'effort' in creating an object-oriented PHP based web-application seems to be the same for a Java based one. Here's our equation for estimating the effort (development/delivery time): ConstructionEffort = f(analysis, design, coding, testing, review, deployment) We were specifically comparing effort estimates in creating an enterprise application with the following: PHP + CakePHP/CodeIgniter (should we have considered others?) Java + Spring + Restlet It's an end-to-end application: Client: Javascript/jQuery + HTML/CSS Middle tier/Business Logic - (Still evaluating PHP/Java) Database: MySQL The effort estimates of the 1st and 3rd tier are constant and relatively independent of the middle tier's technology. At a high level with an initial breakdown into user stories of the requested features as well as a high-level SWAG on the sheer number of classes/SLOC that would be required for PHP doesn't seem to differ by much from what is required of the same in Java. Is this correct? We are basing our initial estimates on the initial prototyping/coding we've done with PHP - we are currently disregarding fluency with the language as a factor, since that'll be an initial hurdle and not a long term impediment IMHO (we also have sufficient time to become quite fluent with PHP). I'm interested in knowing the programmers' perspective with respect to effort when creating similar applications with either of the languages to justify choosing one over the other. Are we missing something here? It seems we are going against popular belief of PHP being quicker to market (or we being very fluent with Java have our vision clouded). It doesn't seem to have any coding/programming effort saving from what we/ve played around with.

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• Displaying a Grid of Data in ASP.NET MVC

  One of the most common tasks we face as a web developers is displaying data in a grid. In its simplest incarnation, a grid merely displays information about a set of records - the orders placed by a particular customer, perhaps; however, most grids offer features like sorting, paging, and filtering to present the data in a more useful and readable manner. In ASP.NET WebForms the GridView control offers a quick and easy way to display a set of records in a grid, and offers features like sorting, paging, editing, and deleting with just a little extra work. On page load, the GridView automatically renders as an HTML <table> element, freeing you from having to write any markup and letting you focus instead on retrieving and binding the data to display to the GridView. In an ASP.NET MVC application, however, developers are on the hook for generating the markup rendered by each view. This task can be a bit daunting for developers new to ASP.NET MVC, especially those who have a background in WebForms. This is the first in a series of articles that explore how to display grids in an ASP.NET MVC application. This installment starts with a walk through of creating the ASP.NET MVC application and data access code used throughout this series. Next, it shows how to display a set of records in a simple grid. Future installments examine how to create richer grids that include sorting, paging, filtering, and client-side enhancements. We'll also look at pre-built grid solutions, like the Grid component in the MvcContrib project and JavaScript-based grids like jqGrid. But first things first - let's create an ASP.NET MVC application and see how to display database records in a web page. Read on to learn more! Read More >

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• How to configure KDE default settings for a new user of a group?

  - by Adobe

  I'm a sys admin on Kubuntu 11.10 machine. Where do I configure the basic config for a new user (say belonging to group "users")? Edit 1: I want to configure langauages - currently my new users get English and Bulgarian Languages. I want them to get English and Russian - and also to set Alt-CapsLock - to be the input-language-switching-combination. Edit 2: How do I configure things in /usr/share/kde4 When I do kdesudo systemsettings and save configurations - only root settings got changed - not the /usr/share/kde4 ones. Edit 3: New user gets the /etc/skel files controlling bash behaviour-appearence. What about the KDE new user's default files - where are they stored? Edit 4: Oh, I found some hints: kde4-config --path config gives a list of folders (separated by the colon) where KDE looks for configs. My machine responded with: /home/boris/.kde/share/config/ /etc/kde4/ /usr/share/kubuntu-default-settings/kde4-profile/default/share/config/ /usr/share/kde4/config/ /usr/share/desktop-base/profiles/kde-profile/share/config/ It looks like third line is where KDE takes the default options. So I found these zilions of settings - but no GUI way to configure it ((. Edit 5: Finally, I've created a dummy user, configured it, and wrote a script which gives it's settings to a given user(s). The trick - is to chown after one transfered the dot files from one user to another. I've tested it - it works fine.

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• Visually and audibly unambiguous subset of the Latin alphabet?

  - by elliot42

  Imagine you give someone a card with the code "5SBDO0" on it. In some fonts, the letter "S" is difficult to visually distinguish from the number five, (as with number zero and letter "O"). Reading the code out loud, it might be difficult to distinguish "B" from "D", necessitating saying "B as in boy," "D as in dog," or using a "phonetic alphabet" instead. What's the biggest subset of letters and numbers that will, in most cases, both look unambiguous visually and sound unambiguous when read aloud? Background: We want to generate a short string that can encode as many values as possible while still being easy to communicate. Imagine you have a 6-character string, "123456". In base 10 this can encode 10^6 values. In hex "1B23DF" you can encode 16^6 values in the same number of characters, but this can sound ambiguous when read aloud. ("B" vs. "D") Likewise for any string of N characters, you get (size of alphabet)^N values. The string is limited to a length of about six characters, due to wanting to fit easily within the capacity of human working memory capacity. Thus to find the max number of values we can encode, we need to find that largest unambiguous set of letters/numbers. There's no reason we can't consider the letters G-Z, and some common punctuation, but I don't want to have to go manually pairwise compare "does G sound like A?", "does G sound like B?", "does G sound like C" myself. As we know this would be O(n^2) linguistic work to do =)...

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• Server-side Architecture for Online Game

  - by Draiken

  basically I have a game client that has communicate with a server for almost every action it takes, the game is in Java (using LWJGL) and right now I will start making the server. The base of the game is normally one client communicating with the server alone, but I will require later on for several clients to work together for some functionalities. I've already read how authentication server should be sepparated and I intend on doing it. The problem is I am completely inexperienced in this kind of server-side programming, all I've ever programmed were JSF web applications. I imagine I'll do socket connections for pretty much every game communication since HTML is very slow, but I still don't really know where to start on my server. I would appreciate reading material or guidelines on where to start, what architecture should the game server have and maybe some suggestions on frameworks that could help me getting the client-server communication. I've looked into JNAG but I have no experience with this kind of thing, so I can't really tell if it is a solid and good messaging layer. Any help is appreciated... Thanks ! EDIT: Just a little more information about the game. It is intended to be a very complex game with several functionalities, making some functionalities a "program" inside the program. It is not an usual game, like FPS or RPG but I intend on having a lot of users using these many different "programs" inside the game. If I wasn't clear enough, I'd really appreciate people that have already developed games with java client/server architecture, how they communicated, any frameworks, apis, messaging systems, etc. It is not a question of lack of knowledge of language, more a question for advice, so I don't end up creating something that works, but in the later stages will have to be rewriten for any kind of limiting reason. PS: sorry if my english is not perfect...

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• How to Set Up a Hadoop Cluster Using Oracle Solaris (Hands-On Lab)

  - by Orgad Kimchi

  Oracle Technology Network (OTN) published the "How to Set Up a Hadoop Cluster Using Oracle Solaris" OOW 2013 Hands-On Lab. This hands-on lab presents exercises that demonstrate how to set up an Apache Hadoop cluster using Oracle Solaris 11 technologies such as Oracle Solaris Zones, ZFS, and network virtualization. Key topics include the Hadoop Distributed File System (HDFS) and the Hadoop MapReduce programming model. We will also cover the Hadoop installation process and the cluster building blocks: NameNode, a secondary NameNode, and DataNodes. In addition, you will see how you can combine the Oracle Solaris 11 technologies for better scalability and data security, and you will learn how to load data into the Hadoop cluster and run a MapReduce job. Summary of Lab Exercises This hands-on lab consists of 13 exercises covering various Oracle Solaris and Apache Hadoop technologies:     Install Hadoop.     Edit the Hadoop configuration files.     Configure the Network Time Protocol.     Create the virtual network interfaces (VNICs).     Create the NameNode and the secondary NameNode zones.     Set up the DataNode zones.     Configure the NameNode.     Set up SSH.     Format HDFS from the NameNode.     Start the Hadoop cluster.     Run a MapReduce job.     Secure data at rest using ZFS encryption.     Use Oracle Solaris DTrace for performance monitoring.  Read it now

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• Is error suppression acceptable in role of logic mechanism?

  - by Rarst

  This came up in code review at work in context of PHP and @ operator. However I want to try keep this in more generic form, since few question about it I found on SO got bogged down in technical specifics. Accessing array field, which is not set, results in error message and is commonly handled by following logic (pseudo code): if field value is set output field value Code in question was doing it like: start ignoring errors output field value stop ignoring errors The reasoning for latter was that it's more compact and readable code in this specific case. I feel that those benefits do not justify misuse (IMO) of language mechanics. Is such code is being "clever" in a bad way? Is discarding possible error (for any reason) acceptable practice over explicitly handling it (even if that leads to more extensive and/or intensive code)? Is it acceptable for programming operators to cross boundaries of intended use (like in this case using error handling for controlling output)? Edit I wanted to keep it more generic, but specific code being discussed was like this: if ( isset($array['field']) ) { echo '<li>' . $array['field'] . '</li>'; } vs the following example: echo '<li>' . @$array['field'] . '</li>';

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• Wireless connected but internet not working, modem is fine because I'm typing over wifi on my android

  - by Sandro Livaja

  I can't connect to the Internet in 11.10. I tried switching my wifi card to another USB slot but nothing changed. Is it possible that the card is able to connect while not being able to receive packages? $ ifconfig eth0 Link encap:Ethernet HWaddr 40:61:86:35:11:b0 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Interrupt:43 Base address:0x6000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) wlan0 Link encap:Ethernet HWaddr 74:ea:3a:8c:d5:5c inet addr:192.168.2.5 Bcast:192.168.2.255 Mask:255.255.255.0 inet6 addr: fe80::76ea:3aff:fe8c:d55c/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:12 errors:0 dropped:0 overruns:0 frame:0 TX packets:102 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1209 (1.2 KB) TX bytes:15329 (15.3 KB)

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• Why is math taught "backwards"? [closed]

  - by Yorirou

  A friend of mine showed me a pretty practical Java example. It was a riddle. I got excited and quickly solved the problem. After it, he showed me the mathematical explanation of my solution (he proved why is it good), and it was completely clear for me. This seems like natural approach for me: solve problems, and generalize. This is very familiar to me, I do it all the time when I am programming: I write a function. When I have to write a similar function, I generalize the problem, grab the generic parts, and refactor them to a function, and solve the original problems as a specialization of the general function. At the university (or at least where I study), things work backwards. The professors shows just the highest possible level of the solutions ("cryptic" mathematical formulas). My problem is that this is too abstract for me. There is no connection of my previous knowledge (== reality in my sense), so even if I can understand it, I can't really learn it properly. Others are learning these formulas word-by-word, and get good grades, since they can write exactly the same to the test, but this is not an option for me. I am a curious person, I can learn interesting things, but I can't learn just text. My brain is for storing toughts, not strings. There are proofs for the theories, but they are also really hard to understand because of this, and in most of the cases they are omitted. What is the reason for this? I don't understand why is it a good idea to show the really high level of abstraction and then leave the practical connections (or some important ideas / practical motivations) out?

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• Game Messaging System Design

  - by you786

  I'm making a simple game, and have decided to try to implement a messaging system. The system basically looks like this: Entity generates message - message is posted to global message queue - messageManager notifies every object of the new message through onMessageReceived(Message msg) - if object wants, it acts on the message. The way I'm making message objects is like this: //base message class, never actually instantiated abstract class Message{ Entity sender; } PlayerDiedMessage extends Message{ int livesLeft; } Now my SoundManagerEntity can do something like this in its onMessageReceived() method public void messageReceived(Message msg){ if(msg instanceof PlayerDiedMessage){ PlayerDiedMessage diedMessage = (PlayerDiedMessage) msg; if(diedMessage.livesLeft == 0) playSound(SOUND_DEATH); } } The pros to this approach: Very simple and easy to implement The message can contain as much as information as you want, because you can just create a new Message subclass that has whatever info necessary. The cons: I can't figure out how I can recycle Message objects to a object pool, unless I have a different pool for each subclass of Message. So I have lots and lots of object creation/memory allocation over time. Can't send a message to a specific recipient, but I haven't needed that yet in my game so I don't mind it too much. What am I missing here? There must be a better implementation or some idea that I'm missing.

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