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  • Multiplayer online game engine/pipeline

    - by Slav
    I am implementing online multiplayer game where client must be written in AS3 (Flash) to embed game into browser and server in C++ (abstract part of which is already written and used with other games). Networking models may differ from each other, but currently I'm looking toward game's logic run on both client and server parts but they're written on different languages while it's not the main problem. My previous game (pretty big one - was implemented with efforts of ~5 programmers in 1.5 years) was mainly "written" within electronic tables as structured objects with implemented inheritance: was written standalone tool which generated AS3 and C++ (languages of platforms to which the game was published) using specified electronic tables file (.xls or .ods). That file contained ~50 tables with ~50 rows and ~50 columns each and was mainly written by game designers which do not know any programming languages. But that game was single-player. Having declared problem with my currently implementing MMO, I'm looking toward some vast pipeline, where will be resolved such problems like: game objects descriptions (which starships exist within game, how much HP they have, how fast move, what damage deal...) actions descriptions (what players or NPCs can do: attack each other, collect resources, build structures, move, teleport, cast spells) - actions are transmitted through server between clients influences (what happens when specified action applied on specified object, e.i "Ship A attacked Ship B: field "HP" of Ship B reduced by amount of field "damage" of Ship A" Influences can be much more difficult, yes, e.i. "damage is twice it's size when Ship has =5 allies around him in a 200 units range during night" and so on. If to be able to write such logic within some "design document" it will be easily possible to: let designers to do their job without programmer's intervention or any bug-prone programming validate described logic transfer (transform, convert) to any programming language where it will be executed Did somebody worked on something like that? Is there some tools/engines/pipelines which concernes with it? How to handle all of this problems simultaneously in a best way or do I properly imagine my tasks and problems to myself?

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  • Class Design - Space Simulator

    - by Peteyslatts
    I have pretty much taught myself everything I know about programming, so while I know how to teach myself (books, internet and reading API's), I'm finding that there hasn't been a whole lot in the way of good programming. So I have two questions: First the broad one: Does anyone have suggestions as to sources for learning about good programming habits and techniques? I'd prefer it if the resource wasn't a 5000 page tome. The more I can read it in installments the better. More specifically: I am finishing up learning the basics of XNA and I want to create a space simulator to test my knowledge. This isn't a full scale simulator, but just something that covers everything I learned. It's also going to be modular so I can build on it, after I get the basics down. One of the early features I want to implement is AI. And I want to take this into account as I'm designing my classes so I can minimize rewriting code. So my question: How should I design ship classes so that both the player and AI can use them? The only idea I have so far is: Create a ship class that contains stats, models, textures, collision data etc. The player and AI would then have the data for position, rotation, health, etc and would base their status off of the ship stats.

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  • How do you keep your basic skills from atrophy?

    - by kojiro
    I've been programming for about 10 years, and I've started to migrate to more of a project management position. I still do coding, but less often now. One of the things that I think is holding me back in my career is that I can't "let go". I think I fear letting hard-won programming skills atrophy while I sit in meetings and annotate requirements. (Not to mention I don't trust people to write requirements who don't understand the code.) I can't just read books and magazines about coding. I'm involved in some open source projects in my free time, and stackoverflow and friends help a bit, because I get the opportunity to help people solve their programming problems without micromanaging, but neither of these are terribly structured, so it's tempting to work first on the problems I can solve easily. I guess what I'd like to find is a structured set of exercises (don't care what language or environment) that… …I can do periodically …has some kind of time requirement so I can tell if I've been goofing off …has some kind of scoring so I can tell if I'm making mistakes Is there such a thing? What would you do to keep your skills fresh?

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  • Knowing state of game in real time

    - by evthim
    I'm trying to code a tic tac toe game in java and I need help figuring out how to efficiently and without freezing the program check if someone won the game. I'm only in the design stages now, I haven't started programming anything but I'm wondering how would I know at all times the state of the game and exactly when someone wins? Response to MarkR: (note: had to place comment here, it was too long for comment section) It's not a homework problem, I'm trying to get more practice programming GUI's which I've only done once as a freshman in my second introductory programming course. I understand I'll have a 2D array. I plan to have a 2D integer array where x would equal 1 and o would equal 0. However, won't it take too much time if I check after every move if someone won the game? Is there a way or a data structure or algorithm I can use so that the program will know the state (when I say state I mean not just knowing every position on the board, the int array will take care of that, I mean knowing that user 1 will win if he places x on this block) of the game at all times and thus can know automatically when someone won?

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  • How to focus on one topic? [closed]

    - by Brian
    I have a huge problem while reading computer books. Every couple pages I'll end up googling something I want to learn more about, but then I'll find something on that page that I'll want to learn more about and google that (sometimes programming related, sometime hardware related). Normally after wasting around 3 hours going into different subjects I'll return to the original text only to repeat the process a few pages later. Any advice for sticking to one subject and learning that in-depth? I have tons of programming books I've read half-way through since I'll become interested in other languages/topics (not that I'm not interested in the books I've started). Also, what would be worth focusing on in depth? I've gone into Python in the most depth but for classes I'm learning Java and assembly (ARM and Motorola 68000). Also, I've taken a class on C++. Lately I've been spending most of my time learning about Linux instead of programming though. I'm not sure what would be worth focusing on the most to get a job. In other words, how can you focus on one topic and not let curiosity about everything else get in the way? Thanks in advance, Brian

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

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

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  • How do I use an API?

    - by GRardB
    Background I have no idea how to use an API. I know that all APIs are different, but I've been doing research and I don't fully understand the documentation that comes along with them. There's a programming competition at my university in a month and a half that I want to compete in (revolved around APIs) but nobody on my team has ever used one. We're computer science majors, so we have experience programming, but we've just never been exposed to an API. I tried looking at Twitter's documentation, but I'm lost. Would anyone be able to give me some tips on how to get started? Maybe a very easy API with examples, or explaining essential things about common elements of different APIs? I don't need a full-blown tutorial on Stack Overflow; I just need to be pointed in the right direction. Update The programming languages that I'm most fluent in are C (simple text editor usually) and Java (Eclipse). In an attempt to be more specific with my question: I understand that APIs (and yes, external libraries are what I was referring to) are simply sets of functions. Question I guess what I'm trying to ask is how I would go about accessing those functions. Do I need to download specific files and include them in my programs, or do they need to be accessed remotely, etc.?

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  • How do I use an API?

    - by GRardB
    Background I have no idea how to use an API. I know that all APIs are different, but I've been doing research and I don't fully understand the documentation that comes along with them. There's a programming competition at my university in a month and a half that I want to compete in (revolved around APIs) but nobody on my team has ever used one. We're computer science majors, so we have experience programming, but we've just never been exposed to an API. I tried looking at Twitter's documentation, but I'm lost. Would anyone be able to give me some tips on how to get started? Maybe a very easy API with examples, or explaining essential things about common elements of different APIs? I don't need a full-blown tutorial on Stack Overflow; I just need to be pointed in the right direction. Update The programming languages that I'm most fluent in are C (simple text editor usually) and Java (Eclipse). In an attempt to be more specific with my question: I understand that APIs (and yes, external libraries are what I was referring to) are simply sets of functions. Question I guess what I'm trying to ask is how I would go about accessing those functions. Do I need to download specific files and include them in my programs, or do they need to be accessed remotely, etc.?

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  • How to tackle an experienced C# Programmer?

    - by nandu.com
    I am a noob in c# and asp.net developing. I have spent 6 months in design and another 6 in sql and asp.net programming. I just know the basics of asp.net and C#. I was programming as per the instruction of my tech leads and all good things changed in a day. :( All my tech leads (2+ experienced) left the company complaining about salary. And instead of those, company has recruited a 5+ experienced programmer cum tech lead (who is very strict), he is expecting me to code anything he says. Previous seniors of me, would say 'use ajax for this, use query for this instead of coding' and so on. I will do it exactly. I am not experienced enough to perform it myself. Now I am in a dilemma. I want to stay in the company and learn some more, but this new tech lead is expecting me to learn everything myself (he is telling me to learn jquery, javascript menus, session and chart in .Net, and so on and do things myself without asking him anything...I mean anything) :(((( PLease suggest to me some good tips to handle him. I think all programmers world wide would have faced a similar problem atleast once in the big programming life. So please..help .. 911

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  • sharing life experience

    - by gcc
    I am a student of computer engineering. I have never done any programming before, and as you can understand, I don't know how to study it or how to make my own programs. My English is weak [edited for clarity - ed], and so if you don't like the choices I list, please feel free to provide others. How should I study? How should I learn programming languages? Study completely from a book. Don't study from a book, just try writing code. A mix of the two; study from a book, then try writing code. Study half the book, then write the code by hand on paper. Listed to the teacher, then try to solve general problems (those not from any specific chapter). I have send that question to stackoverflow before when I am at first year. Now, I want to construct webpage to guide fresh students by giving advise of yours and mines.Maybe, you wonder Why I want to construct webpage , I just want help the other student. I am giving a link to that question < http://stackoverflow.com/questions/3389465/how-should-i-study-programming-languagess If you have other advice, feel free. EDIT: This web cite, I think , is constructed to share member's life experience and also I know these experiences is valuable . So I have no right to want your opinion, But I want your opinion / experience even if you think it is not so helpful to other

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  • How should an undergraduate programmer organize his time learning the maximum possible?

    - by nischayn22
    I started programming lately(pre-final year of a CS degree) and now feel like there's a sea of uncovered treasure for me out there. So, I decided to cover as much as is possible before I look out for a job after graduation. So, I started to read books (The C++ Programming Language, Introduction to Algorithms, Cracking the Coding Interview, Programming Pearls,etc ) participate in StackExchange sites, solving problems (InterviewStreet and ProjectEuler), coding for open source, chatting to fellow programmers/mentors and try to learn more and more. Good,then what's the problem?? The problem is I am trying to do many things, but I am doubtful that I am still utilizing my time properly. I am reading many books and sometimes I just leave a book halfway (jumping from one book to another), sometimes I spend way too much time on chatting and also in getting lost somewhere in the huge internet world, and lastly the wasteful burden of attending classes (I don't think my teachers know good enough or I prefer learning on my own) May be some of you had similar situation. How did you organize your time? Or what do you think is the best way to organize it for an undergraduate? Also what mistakes am I making that you can warn me of

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  • JVM Language Summit in July

    - by Tori Wieldt
    A reminder that the 2012 JVM Language Summit is happening July 30–August 1, 2012 in Santa Clara, CA. The JVM Language Summit is an open technical collaboration among language designers, compiler writers, tool builders, runtime engineers, and VM architects, sharing their experiences as creators of programming languages for the JVM, and of the JVM itself. Non-JVM developers are welcome to attend or speak on their runtime, VM, or language of choice. About 70 language and VM implementers attended last year—and over one third presented. What’s at the JVM Language Summit? Three days of technical presentations and conversations about programming languages and the JVM. Prepared talks by numerous visiting language experts, OpenJDK engineers, and other Java luminaries. Many opportunities to visit and network with your peers. Da Vinci Machine Project memorabilia. Dinner at a local restaurant, such as last year’s Faultline Brewing Company. A chance to help shape the future of programming languages on the JVM. Space is limited: This summit is organized around a single classroom-style room, to support direct communication between participants. To cover costs, there is a nominal conference fee of $100. Learn more.

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  • Moving From IT to Embedded software Developing

    - by Ameer Adel
    i worked for two years at a channel station, managing various Types of tasks, varying from printers installation, software solution, down to managing and maintaining server automation, to be honest, i always been enthusiastic about programming, i studied at some affordable college and finished my IT path successfully, my graduation project was in C# ADO.NET couple of years ago. Obviously it was so much of a beginner spaghetti code than a well furnished code. I also had the chance; after leaving the IT career, to study about some ASP.NET MVC and web apps development. I have rookie level of coding skills due to the poor level of education i endured, and sufficient resources. Currently i m working as a trainee in a newly opened embedded software development company, that is being said, i am, as i sound, have a little idea about the algorithms included, as i was reading for the past couple of days, embedded system development requires more strict coding skills, including memory management, CPU optimization according to its architect, and couple of other tricks regarding the display, and power management if mobile.. etc. My question is, What type of Algorithms am i supposed to use in such cases, as i mentioned before, i am really enthusiastic about learning programming skills and algorithms related to embedded systems and programming languages, including C/C++, Java, C#, and some EC++ if still operational.

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  • What are some good ways for an intermediate programmer to build skills?

    - by Jordan
    Preface: I work mostly in Python, and Web Dev languages (HTML, CSS, Javascript and Jquery, PHP) I'm proficient at coding but I want to get better. In larger more advanced projects my programming skills break down. The more code there is the more trouble I have fitting all the pieces together. I understand syntax well, and I can catch and correct errors fairly easier. But the more advanced it gets the more I struggle. I believe I have a good understand of the basic and nuts and bolts of programming and I understand what's going on, but when it comes to larger projects, especially ones with heavy math involved my confidence flags and I start making mistakes. It's not that I can't do it, I'm just not used to doing it. Does anyone have any advice for someone who knows programming, but wants to get better? The only tutorials I can really find are beginner basic type stuff. Basically what I'm saying is I want to be confident when I'm tackling advanced projects, but I can't because I have little experience dealing with difficult situations.

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  • How much a programmer should read in order to keep himself updated? [closed]

    - by anything
    There are lots of technical books available. Below are few links which lists some good books If you could only have one programming related book on your bookshelf what would it be and why? What non-programming books should a programmer read to help develop programming/thinking skills? Best books on the theory and practice of software architecture? http://stackoverflow.com/questions/1711/what-is-the-single-most-influential-book-every-programmer-should-read ... and the list can go on and on and on. It will be really difficult to read all of the above mentioned books. I am not sure if its even possible for anyone to do that. Even if you filter it based on one's area of interest or work, list is still very large. .. and the technology keeps on changing (even more books :-( ) So, my question is how much a programmer should read lets say per year? How much hours one should put in such activities to keep oneself up to date? How do we find out the time required? PS: Average programmer reads less than one book per year (Code complete). What about the good programmers?

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  • What is involved with writing a lobby server?

    - by Kira
    So I'm writing a Chess matchmaking system based on a Lobby view with gaming rooms, general chat etc. So far I have a working prototype but I have big doubts regarding some things I did with the server. Writing a gaming lobby server is a new programming experience to me and so I don't have a clear nor precise programming model for it. I also couldn't find a paper that describes how it should work. I ordered "Java Network Programming 3rd edition" from Amazon and still waiting for shipment, hopefully I'll find some useful examples/information in this book. Meanwhile, I'd like to gather your opinions and see how you would handle some things so I can learn how to write a server correctly. Here are a few questions off the top of my head: (may be more will come) First, let's define what a server does. It's primary functionality is to hold TCP connections with clients, listen to the events they generate and dispatch them to the other players. But is there more to it than that? Should I use one thread per client? If so, 300 clients = 300 threads. Isn't that too much? What hardware is needed to support that? And how much bandwidth does a lobby consume then approx? What kind of data structure should be used to hold the clients' sockets? How do you protect it from concurrent modification (eg. a player enters or exists the lobby) when iterating through it to dispatch an event without hurting throughput? Is ConcurrentHashMap the correct answer here, or are there some techniques I should know? When a user enters the lobby, what mechanism would you use to transfer the state of the lobby to him? And while this is happening, where do the other events bubble up? Screenshot : http://imageshack.us/photo/my-images/695/sansrewyh.png/

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  • Book / software to learn ERP?

    - by user22311
    For a while I've been wanting to learn ERP. What I would like to do is set up a system, and then practice running a business doing things like generating invoices, raising purchase orders, producing monthly accounts, keeping track of fixed assets etc. Then look at enhancing the system further by adding custom code. I know there are a variety of open source ERP systems around, but really I would prefer a widely used commercial system as having familiarity with such a system would be more marketable. So are there any such systems that have a free developer version available? I've looked around, but I've had trouble finding such a system. Also I would like to find a good book or more likely books to read on ERP. Ideally I would be able to get an indepth explanation ERP from a business perspective, ie the accounting operations it supports, how to do all the regular accounting tasks, configuration, business operations best practices, accounting controls and so on. In addition I would like an IT perspective, ie setting up the system, developing forms and reports. Unfortunately the few books I've looked at have been really superficial and totally inadequate. They either fall into the beginning programmer camp, where they use the programming tools but concentrate on programming 101 topics like loops, flow control etc. Or they cover setting up the system with lots of screen shots, but little substance as to why things should be done a certain way. I have a programming background but no real experience in implementing ERP systems. Also I have a reasonable accounting knowledge, and have used ERP systems in various jobs, but only to a very limited degree. So are there any ERP experts who can point me in the right direction? Thanks.

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  • How do I tell my parents that landing a job is what actually counts?

    - by shovonr
    On one side, I just want to get a degree with a 3.0 GPA. On the other side, my parents want more than just a 3. Now here's the thing. I program with a passion. I spend day and night programming. And I ace all my programming courses. However, I do terrible on all my elective courses -- such as writing, history, and all that stuff -- which only leaves me with a 3.1 to 3.2 GPA. And my parents want more. They think that university is like high school, where you need super-stellar grades to get to the next level. But they don't realize that good enough grades will land me a job. And they don't realize that a programmer needs to practice to become good at programming, and that having good skills is what will land a job in a nice software development company. Thankfully, though, they don't threaten to beat me with a baseball bat or anything like that. They just occasionally give me the little "tsk-tsk". But even that little "tsk-tsk" makes me feel guilty for opening up an IDE. And on top of that, I procrastinate because of that feeling of guilt. So now, I want to come clean with them. I want to know what's a good way to do that. [Edit] OK, so now, I realized, I should aim for higher grades, as some have suggested below.

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  • Problem with understanding how to start

    - by Coolface
    Okay, this might be a little off-topic but i try anyway. Sorry to bother. So i'm working as sysadmin for at least 5 years now and i quite enjoy IT field in general. Somehow i was never interested in programming much but always want to learn something at least easy and for personal usage. As sysadmin i need scripting skills so learn shell scripting without much problems, i also try to learn pascal, delphi, basic over time and must recent was python. Well, my problem is when i try to learn programming i just can't apply what i learn from the books to the real word. What i mean is i understand there are data structures, algorithms, variables, lib's, if-then logic, etc. but i just can't understand how to apply this things when i want to do real things. Like i want to get a something simple as parse web page, i draw a quick algorithm like get a web page, find a word on it and write a to file, on the paper everything look simple but when i get to the coding i just stuck pretty much from the start. I try read code of the real programs that just totally confusing especially big parts with many classes so i'm just quickly lost a trail what this code do. I think i just lack some fundamentals to see a big picture but don't really know what this might be? Or maybe i just don't have a passion to programming at all... My best bet was a shell scripting so i have really no problems to write complex scripts but this just not enough. Recently i was read around 5 or 6 python books because everyone say it's so easy even kid can code something but still no much luck, python is good and easy but i can't make something harder then a prodecurial style code like in bash for easy things but when i want harder things i'm still stuck. In college i was also not a math and tech guy and like to study non-tech stuff mostly like economy, psychology maybe that my problem? Anyway any advice would be greatly appriciated.

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  • Using TPL and PLINQ to raise performance of feed aggregator

    - by DigiMortal
    In this posting I will show you how to use Task Parallel Library (TPL) and PLINQ features to boost performance of simple RSS-feed aggregator. I will use here only very basic .NET classes that almost every developer starts from when learning parallel programming. Of course, we will also measure how every optimization affects performance of feed aggregator. Feed aggregator Our feed aggregator works as follows: Load list of blogs Download RSS-feed Parse feed XML Add new posts to database Our feed aggregator is run by task scheduler after every 15 minutes by example. We will start our journey with serial implementation of feed aggregator. Second step is to use task parallelism and parallelize feeds downloading and parsing. And our last step is to use data parallelism to parallelize database operations. We will use Stopwatch class to measure how much time it takes for aggregator to download and insert all posts from all registered blogs. After every run we empty posts table in database. Serial aggregation Before doing parallel stuff let’s take a look at serial implementation of feed aggregator. All tasks happen one after other. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();           for (var index = 0; index <blogs.Count; index++)         {              ImportFeed(blogs[index]);         }     }       private void ImportFeed(BlogDto blog)     {         if(blog == null)             return;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                 }       private void ImportRssFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = RssFeed.Create(uri);           foreach (var item in feed.Channel.Items)         {             SaveRssFeedItem(item, blog.Id, blog.CreatedById);         }     }       private void ImportAtomFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           foreach (var item in feed.Entries)         {             SaveAtomFeedEntry(item, blog.Id, blog.CreatedById);         }     } } Serial implementation of feed aggregator downloads and inserts all posts with 25.46 seconds. Task parallelism Task parallelism means that separate tasks are run in parallel. You can find out more about task parallelism from MSDN page Task Parallelism (Task Parallel Library) and Wikipedia page Task parallelism. Although finding parts of code that can run safely in parallel without synchronization issues is not easy task we are lucky this time. Feeds import and parsing is perfect candidate for parallel tasks. We can safely parallelize feeds import because importing tasks doesn’t share any resources and therefore they don’t also need any synchronization. After getting the list of blogs we iterate through the collection and start new TPL task for each blog feed aggregation. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();                var tasks = new Task[blogs.Count];           for (var index = 0; index <blogs.Count; index++)         {             tasks[index] = new Task(ImportFeed, blogs[index]);             tasks[index].Start();         }           Task.WaitAll(tasks);     }       private void ImportFeed(object blogObject)     {         if(blogObject == null)             return;         var blog = (BlogDto)blogObject;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                }       private void ImportRssFeed(BlogDto blog)     {          var uri = new Uri(blog.RssUrl);          var feed = RssFeed.Create(uri);           foreach (var item in feed.Channel.Items)          {              SaveRssFeedItem(item, blog.Id, blog.CreatedById);          }     }     private void ImportAtomFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           foreach (var item in feed.Entries)         {             SaveAtomFeedEntry(item, blog.Id, blog.CreatedById);         }     } } You should notice first signs of the power of TPL. We made only minor changes to our code to parallelize blog feeds aggregating. On my machine this modification gives some performance boost – time is now 17.57 seconds. Data parallelism There is one more way how to parallelize activities. Previous section introduced task or operation based parallelism, this section introduces data based parallelism. By MSDN page Data Parallelism (Task Parallel Library) data parallelism refers to scenario in which the same operation is performed concurrently on elements in a source collection or array. In our code we have independent collections we can process in parallel – imported feed entries. As checking for feed entry existence and inserting it if it is missing from database doesn’t affect other entries the imported feed entries collection is ideal candidate for parallelization. internal class FeedClient {     private readonly INewsService _newsService;     private const int FeedItemContentMaxLength = 255;       public FeedClient()     {          ObjectFactory.Initialize(container =>          {              container.PullConfigurationFromAppConfig = true;          });           _newsService = ObjectFactory.GetInstance<INewsService>();     }       public void Execute()     {         var blogs = _newsService.ListPublishedBlogs();                var tasks = new Task[blogs.Count];           for (var index = 0; index <blogs.Count; index++)         {             tasks[index] = new Task(ImportFeed, blogs[index]);             tasks[index].Start();         }           Task.WaitAll(tasks);     }       private void ImportFeed(object blogObject)     {         if(blogObject == null)             return;         var blog = (BlogDto)blogObject;         if (string.IsNullOrEmpty(blog.RssUrl))             return;           var uri = new Uri(blog.RssUrl);         SyndicationContentFormat feedFormat;           feedFormat = SyndicationDiscoveryUtility.SyndicationContentFormatGet(uri);           if (feedFormat == SyndicationContentFormat.Rss)             ImportRssFeed(blog);         if (feedFormat == SyndicationContentFormat.Atom)             ImportAtomFeed(blog);                }       private void ImportRssFeed(BlogDto blog)     {         var uri = new Uri(blog.RssUrl);         var feed = RssFeed.Create(uri);           feed.Channel.Items.AsParallel().ForAll(a =>         {             SaveRssFeedItem(a, blog.Id, blog.CreatedById);         });      }        private void ImportAtomFeed(BlogDto blog)      {         var uri = new Uri(blog.RssUrl);         var feed = AtomFeed.Create(uri);           feed.Entries.AsParallel().ForAll(a =>         {              SaveAtomFeedEntry(a, blog.Id, blog.CreatedById);         });      } } We did small change again and as the result we parallelized checking and saving of feed items. This change was data centric as we applied same operation to all elements in collection. On my machine I got better performance again. Time is now 11.22 seconds. Results Let’s visualize our measurement results (numbers are given in seconds). As we can see then with task parallelism feed aggregation takes about 25% less time than in original case. When adding data parallelism to task parallelism our aggregation takes about 2.3 times less time than in original case. More about TPL and PLINQ Adding parallelism to your application can be very challenging task. You have to carefully find out parts of your code where you can safely go to parallel processing and even then you have to measure the effects of parallel processing to find out if parallel code performs better. If you are not careful then troubles you will face later are worse than ones you have seen before (imagine error that occurs by average only once per 10000 code runs). Parallel programming is something that is hard to ignore. Effective programs are able to use multiple cores of processors. Using TPL you can also set degree of parallelism so your application doesn’t use all computing cores and leaves one or more of them free for host system and other processes. And there are many more things in TPL that make it easier for you to start and go on with parallel programming. In next major version all .NET languages will have built-in support for parallel programming. There will be also new language constructs that support parallel programming. Currently you can download Visual Studio Async to get some idea about what is coming. Conclusion Parallel programming is very challenging but good tools offered by Visual Studio and .NET Framework make it way easier for us. In this posting we started with feed aggregator that imports feed items on serial mode. With two steps we parallelized feed importing and entries inserting gaining 2.3 times raise in performance. Although this number is specific to my test environment it shows clearly that parallel programming may raise the performance of your application significantly.

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  • When to use CouchDB vs RDBMS

    - by Andrew Whitehouse
    I am looking at CouchDB, which has a number of appealing features over relational databases including: intuitive REST/HTTP interface easy replication data stored as documents, rather than normalised tables I appreciate that this is not a mature product so should be adopted with caution, but am wondering whether it is actually a viable replacement for an RDBMS (in spite of the intro page saying otherwise - http://couchdb.apache.org/docs/intro.html). Under what circumstances would CouchDB be a better choice of database than an RDBMS (e.g. MySQL), e.g. in terms of scalability, design + development time, reliability and maintenance. Are there still cases where an RDBMS is still clearly the right choice? Is this an either-or choice, or is a hybrid solution more likely to emerge as best practice?

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  • Good way to edit the previous defined class in ipython

    - by leo
    Hi, I am wondering a good way to follow if i would like to redefine the members of a previous defined class in ipython. say : I have defined a class intro like below, and later i want to redefine part of the function definition _print_api. Any way to do that without retyping it . class intro(object): def _print_api(self,obj): def _print(key): if key.startswith('_'): return '' value = getattr(obj,key) if not hasattr(value,im_func): doc = type(valuee).__name__ else: if value.__doc__ is None: doc = 'no docstring' else: doc = value.__doc__ return ' %s :%s' %(key,doc) res = [_print(element) for element in dir(obj)] return '\n'.join([element for element in res if element != '']) def __get__(self,instance,klass): if instance is not None: return self._print(instance) else: return self._print_api(klass)

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  • Emacs enum indentation

    - by Masterofpsi
    I'm having a problem with Emacs's indentation of Java enums. While it indents the first member OK, it wants to give all of the rest of the static enum members an additional level of indentation. It looks like this: class MyClass { public enum MyEnum { ONE(1), //good TWO(2), // not good! THREE(3), FOUR(4); private final int value; } } When I run C-c C-s on the line that opens the enum, it gives me ((inclass 1) (topmost-intro 1)), which doesn't seem quite right -- it seems like it should be giving brace-list-open. When I run it on the first enum member, it gives me ((defun-block-intro 21)), which is definitely not right. Every subsequent member gives (statement-cont 50). I'm in java-mode and I'm using the java style of indentation. Does anyone know what the problem might be?

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  • [Wordpress] How do I return values from custom created meta box?

    - by Steven
    I've just followed this example from Wordpress and I have successfully added an extra Meta Box in Post interface, and the value is stored in DB. Now my question is, how can I retrieve and display the content of this meta box? I'm trying the following code: $intro = get_post_meta($post->ID, 'post_intro', true); echo $intro; But I get nada. What am I doing wrong? And while I'm here, does anybody know if I can place this extra meta box above the default text box in Wordpress post page?

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