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  • Are the only types of data "sources" static and dynamic?

    - by blunders
    Thinking that there might be others, but not sure -- but before getting into that, let me explain what I mean by static and dynamic data sources. Static (or datastore) - Meaning that the data's state is non-changing, and if was changed, that would be a new state, and the old data would be considered stateless; meaning it no longer is known to exist, or not exist. Another way of possibly looking at a static data source might be that if read and written back without modification, the checksum for before and after should be exactly the same regardless of the duration of time between the reading and rewriting of the data. Examples: Photos, Files, Database Record, Dynamic (or datastream) - Meaning that the data's state is known to be in flux, and never expected to be the same per input. Example: Live video/audio feed, Stock Market feed, First let me say, the above is a very loose mapping of the concepts, and I'd welcome any feedback. Next, onto the core of the question, that being are these the only two types of data sources. My guess, is that yes, they are -- but that there are hybrid versions of the two. That being, streaming data that has a fixed state. For example, the data being streamed has a checksum given and each unique checksum is known to be a single instance of static data. On the flip side, static data could be chained via say a version control system; when played back, each version might be viewed as a segment of a stream; thing is, the very fact that it can be played back makes the data source static. Another type might be that the data source is being organically discovered, and it's simply unknown what the state is. Questions, feedback, requests -- just comment, thanks!!

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  • EBS ATG Advisor Webcasts - FREE!

    - by cwarticki
    For June 2012 we have scheduled 2 Webcasts - E-Business Suite OAM Overview and Usage session and the E-Business Suite Workflow Avisor.  We are driving 2 sessions for a better global alignment. E-Business Suite - OAM Overview and Monitoring   Agenda Oracle Applications Manager (OAM) Overview Log files Diagnostics and Logging Concurrent processing through OAM Applications Dashboard Troubleshooting Patch Management. Patch Wizard OAM "How To" Documents Questions &Answers EMEA Session : July 10, 2012 at 09:00 AM UK / 10:00 AM CET / 13:30 India / 17:00 Japan / 18:00 Australia Details & Registration : Note 1466056.1 Direct link to register in WebEx US Session : July 11, 2012 at 18:00 UK / 19:00 CET / 10:00 AM Pacific / 11:00 AM Mountain/ 01:00 PM Eastern Details & Registration : Note 1466057.1 Direct link to register in WebEx E-Business Suite - Workflow Analyzer - Follow-Up Agenda Overview of Workflow Analyzer Enhancements implemented in the latest Release Questions & Answers EMEA Session : July 24, 2012 at 09:00 AM UK / 10:00 AM CET / 13:30 India / 17:00 Japan / 18:00 Australia Details & Registration : Note 1466058.1 Direct link to register in WebEx US Session : July 25, 2012 at 18:00 UK / 19:00 CET / 10:00 AM Pacific / 11:00 AM Mountain/ 01:00 PM Eastern Details & Registration : Note 1466059.1 Direct link to register in WebEx Schedules, recordings and the Presentations of the Advisor Webcast drove under the EBS Applications Technology area can be found in Note 1186338.1. Current Schedules of Advisor Webcast for all Oracle Products can be found on Note 740966.1 Post Presentation Recordings of the Advisor Webcasts for all Oracle Products can be found on Note 740964.1 If you have any question about the schedules or if you have a suggestion for an Advisor Webcast to be planned in future, please send an E-Mail to Ruediger Ziegler.

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  • Proper method to update and draw from game loop?

    - by Lost_Soul
    Recently I've took up the challenge for myself to create a basic 2d side scrolling monster truck game for my little brother. Which seems easy enough in theory. After working with XNA it seems strange jumping into Java (which is what I plan to program it in). Inside my game class I created a private class called GameLoop that extends from Runnable, then in the overridden run() method I made a while loop that handles time and such and I implemented a targetFPS for drawing as well. The loop looks like this: @Override public void run() { long fpsTime = 0; gameStart = System.currentTimeMillis(); lastTime = System.currentTimeMillis(); while(game.isGameRunning()) { currentTime = System.currentTimeMillis(); long ellapsedTime = currentTime - lastTime; if(mouseState.leftIsDown) { que.add(new Dot(mouseState.getPosition())); } entities.addAll(que); game.updateGame(ellapsedTime); fpsTime += ellapsedTime; if(fpsTime >= (1000 / targetedFPS)) { game.drawGame(ellapsedTime); } lastTime = currentTime; } The problem I've ran into is adding of entities after a click. I made a class that has another private class that extends MouseListener and MouseMotionListener then on changes I have it set a few booleans to tell me if the mouse is pressed or not which seems to work great but when I add the entity it throws a CME (Concurrent Modification Exception) sometimes. I have all the entities stored in a LinkedList so later I tried adding a que linkedlist where I later add the que to the normal list in the update loop. I think this would work fine if it was just the update method in the gameloop but with the repaint() method (called inside game.drawGame() method) it throws the CME. The only other thing is that I'm currently drawing directly from the overridden paintComponent() method in a custom class that extends JPanel. Maybe there is a better way to go about this? As well as fix my CME? Thanks in advance!!!

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  • How is determined an impact of a requirement change on the existing code?

    - by MainMa
    Hi, How companies working on large projects evaluate an impact of a single modification on an existing code? Since my question is probably not very clear, here's an example: Let's take a sample business application which deals with tasks. In the database, each task has a state, 0 being "Pending", ... 5 - "Finished". A new requirement adds a new state, between 2nd and 3rd one. It means that: A constraint on the values 1 - 5 in the database must be changed, Business layer and code contracts must be changed to add a new state, Data access layer must be changed to take in account that, for example the state StateReady is now 6 instead of 5, etc. The application must implement a new state visually, add new controls for it, new localized strings for tool-tips, etc. When an application is written recently by one developer, it's more or less easy to predict every change to do. On the other hand, when an application was written for years by many people, no single person can anticipate every change immediately, without any investigation. So since this situation (such changes in requirements) is very frequent, I imagine there are already some clever techniques and ways to predict the impact. Is there any? Do you know any books which deal about this subject? Note: my question is not related to How do you deal with changing requirements? question. In fact, I'm not interested in evaluating the cost of a change, but rather the way to predict the parts of an application which will be concerned by the change. What will be those changes and how difficult they are really doesn't matter in my question.

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

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

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  • Unified data source for k2 installed Joomla websites

    - by Özkan ÖZLÜ
    I am responsible for a few web sites of my organization. I use Joomla! 2.5.9 for those web sites. They all are running at the same server. I use K2 component for content managing. I have a general website in which shows all the staff information at the 'Staff' page. Also some of those people and their contents are shown in another department's website. So, there are databases for each web site. For example: In the general website (let's say general.org), when I click on the 'Staff' menu item, page shows all of the people work at my organization. Also they work at different departments. In another web site (eg: education.general.org) when I click on the 'Staff' menu item, it shows the people work at education department. But for each web site, I have different user accounts which means a modification in one of them does not affect the other one. If the one of the education staff tries to change his profile picture on the education web site, he also has to do it on the general web site. And sometimes one person might be working at two departments. Thus he has to edit three times of his data. Is it possible to merge the records for all websites? In other words, I want everyone to insert/update their data on the general web site, and the other web sites will be updated automatically.

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  • XNA 2D Spritesheet drawing rendering problem

    - by user24092
    I'm making a tile-based game, using one spritesheet containing all tile graphics. Each tile has a size of 32x32 pixels. The main problem is: when I draw the tile to the screen, if the tile position x and y are not rounded or if scale is activated in spriteBatch.Draw() method (scale != 1.0f), I get some lines of adjacent tiles on the spritesheet into the current tile drawed. I already tried setting SamplerState to PointClamp, removing AntiAlias, but still doesn't work. Here I'll show images of some tests that I made, with a test sprite sheet that I've created (I made a 9x9 spritesheet, with each sprite of size 32x32 containing a unique solid color). Tests: http://img6.imageshack.us/img6/5946/testsqj.png SpriteSheet used: http://imageshack.us/a/img821/1341/tilesm.png Already tried to remove anti-alias, set PointClamp as sampler state, but still getting this issue, XNA keeps drawing part of the adjacent pixels of the texture on the screen. What I want is to get the correct area of the tilesheet texture (as seen in the first test, that gets just the yellow pixels). My question is: Is there any way that I can fix this, WITHOUT adding tile spacing or any other modification involving the tilesheet? Maybe disabling a texture filtering that is done by XNA, or something like that.

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  • 2D Smooth Turning in a Tile-Based Game

    - by ApoorvaJ
    I am working on a 2D top-view grid-based game. A ball that rolls on the grid made up of different tiles. The tiles interact with the ball in a variety of ways. I am having difficulty cleanly implementing the turning tile. The image below represents a single tile in the grid, which turns the ball by a right angle. If the ball rolls in from the bottom, it smoothly changes direction and rolls to the right. If it rolls in from the right, it is turned smoothly to the bottom. If the ball rolls in from top or left, its trajectory remains unchanged by the tile. The tile shouldn't change the magnitude of the velocity of the ball - only change its direction. The ball has Velocity and Position vectors, and the tile has Position and Dimension vectors. I have already implemented this, but the code is messy and buggy. What is an elegant way to achieve this, preferably by modification of the ball's Velocity vector by a formula?

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  • Identify high CPU consumed thread for Java app

    - by Vincent Ma
    Following java code to emulate busy and Idle thread and start it. import java.util.concurrent.*;import java.lang.*; public class ThreadTest {    public static void main(String[] args) {        new Thread(new Idle(), "Idle").start();        new Thread(new Busy(), "Busy").start();    }}class Idle implements Runnable {    @Override    public void run() {        try {            TimeUnit.HOURS.sleep(1);        } catch (InterruptedException e) {        }    }}class Busy implements Runnable {    @Override    public void run() {        while(true) {            "Test".matches("T.*");        }    }} Using Processor Explorer to get this busy java processor and get Thread id it cost lots of CPU see the following screenshot: Cover to 4044 to Hexadecimal is oxfcc. Using VistulVM to dump thread and get that thread. see the following screenshot In Linux you can use  top -H to get Thread information. That it! Any question let me know. Thanks

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  • Smarter Search Results in NetBeans IDE 7.2

    - by Geertjan
    After you search your code using NetBeans IDE (using Ctrl-F for "Find" or Ctrl-H for "Replace"), you see the Search Results window, which looks like this: At least, the above is how it looks in NetBeans IDE 7.2. Before that, you didn't have all those extra columns (which can be displayed in the Search Results window after clicking the small button top right in the view) and you also didn't have the quick search (which is invoked by typing directly into the Search Results window), as can be seen here: So, the Search Results window now provides a lot more info than before. Being able to know the path to a file I've found, as well as the last modification date, file size, and the number of matches within the file, is useful at the end of a search process. In the NetBeans IDE 7.2 New & Noteworthy, the above changes are described in the Utilities section, as well as in the Quick Search in OutlineView section, where you can read that these are generic solutions that can be used in your own OutlineViews. Other OutlineViews in NetBeans IDE 7.2, such as the Debugger window, now also have these new features. A related article worth reading is Beefed Up Code Navigation Tools in NetBeans IDE 7.2. 

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  • How to factorize code in Unreal Kismet (i.e. "Material Function"s for Kismet)

    - by Georges Dupéron
    In the Unreal Development Kit, when using the Material Editor, one can factorize frequently-used groups of nodes by creating a Material Function (content Browser ? right-click ? new matrial function, IIRC). When defining the behaviour of some actor in Kismet, one can easily have a dozen nodes involved. If I have many actors that share the same behaviour, then I'll copy-paste these nodes, and change the variables so they point to the other actors. This leads to inconsistencies (a modification in the behaviour of an actor isn't propagated in the copy-pasted nodes), complexity (you end up with hundreds of nodes), and generally useless effort. My question is : Can I create a "kismet function", just like a material function ? Note: I'd rather avoid using UnrealScript. I don't even know where to type UnrealScripts, don't know where the documentation is and more generally don't have enough time to invest in learning UnrealScript. This "kismet function" feature must be usable by graphists (with little programming knowledge). If a (simple) script suffices to add this feature in the Kismet editor, so that one can create several "functions" without using UnrealScript, then fine, but I don't really want to have to write a script each time I want to factorize a few nodes. Thanks for any information !

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  • How much overhead is there in persistent connections?

    - by nynex
    Ok so I'm musing over a little side project I want to start. Essentially its a multi-session web based FTP client. Multi-session in that you can log into several FTP servers at the same time and perform operations like moving a file from one FTP server to another. I'm doing this mainly to brush up on the new webdev technologies, particularly websockets. I'm using node.js + socket.io to keep a persistent bi-directional connection between the web browser and the web server. The web server will also have persistent connections to each FTP server the user has logged into. So if there are 100 concurrent users each logged into 5 ftp accounts, the web server will have 100 websocket connections + 500 ftp connections. Is servicing 600 connections a lot? I know it depends on the hardware resources of the server but is something like this doable on a budget? Are there more efficient means of doing something like this? I know its unlikely that this project will really get popular but I want it to scale well regardless. Thanks for any help, I've still got a lot to learn.

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  • In an online questionnaire, what is a best way to design a database for keeping track of users all attempts?

    - by user1990525
    We have a web app where users can take online exams. Exam admin will create a questionnaire. A questionnaire can have many Questions. Each question is a multiple choice question (MCQ). Lets say an admin creates a questionnaire with 10 questions. Users attempt those questions. Now, unlike real exams users can attempt single questionnaire multiple times. And we have to keep track of his all attempts. e.g. User_id Questionnaire_id question_id answer attempt_date attempt_no 1 1 1 a 1 June 2013 1 1 1 2 b 1 June 2013 1 1 1 1 c 2 June 2013 2 1 1 2 d 2 June 2013 2 Now it can also happen that after user has attempted same questionnare twice, admin can delete a question from same questionnaire, but users attempt history should still have reference to that so that user can see his that question in his attempt history in spite of admin deleting that question. If user now attempts this changed questionnaire he should see only 1 question. User_id Questionnaire_id question_id answer attempt_date attempt_no 1 1 1 a 3 June 2013 3 Also, after this user modified some part of question, users attempt history should show question before modification while any new attempt should show modified question. How do we manage this at the database level? My first gut feeling was that, For deletes, do not do physical delete, just make a question inactive so that history can still keep track of users attempt. For modifications, create versions for questions and each new attempt refres to latest version of each question and history keeping reference to version of question at attempt time.

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  • Blocking popups and ads

    - by user74364
    I'm having a fight with ads, popups and tracking cookies. But i'm having some issues. Software used: Chromium 18.0.1025.168 Extensions used: Adblock Plus (Beta)1.2 AdBlock+ Element Hiding Helper1.1.9.18 Better Pop Up Blocker2.1.6 Ghostery3.0.0 With this configuration, i'm always getting this error: Warning: This extension failed to modify a network request because the modification conflicted with another extension. I know if i disable "better popup", this goes away. It's perfectly normal, due to those extensions trying to block the same things. Problem is, i can't live without all of them! Can anyone advise me about some good configuration? Can't live without adblock plus, because i hate ads. Betterpopup blocker is essential too (believe me, chrome doesn't block a lot of popups, and i have a website or 2 that can proove that.) And ghostery is a must... i can't bare the idea of being tracked all the time by some companies. So i'm kinda lost here! everything is needed, but they conflict with each other. i mean, it has to exist a perfect combination out there, i know i'm not the only one hating the privacy issues nowadays! really thankful for any tips guys

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  • Do the benefits of Resin/Quercus outweigh the overhead?

    - by Craige
    Lately, I've been looking more and more into Resin + Quercus as a technology to develop an application of mine. The reason I started looking into it was that this application has high reporting needs, a lot of which cannot (or realistically, should not) be created in real-time. Java would offer a nice backend to queue and generate reports. Also, with Quercus I would be able to develop my data models in Hibernate, and use them "from PHP", thus effectively stretching these models across front and back-end. This same concept would also apply to any front/back-end common business logic, which could be developed in Java libraries. Now, the downside is that whichever front-end (PHP) MVC Framework I choose (my goal was Symfony 2), it is unlikely to work without some heavy modification, if it can work at all. Quercus is a pretty close implementation of PHP, and is supposed to be compatible with PHP5.3, so namespaces and closures SHOULDN'T be a problem, but when I tried to run an existing Symfony 1.4 app, I failed miserably. So, my question to you is, do you think the benefits of Resin + Quercus outweigh the overhead of using a not-so-perfect/stable implementation of PHP? If this were your application, and your goal was and end-product, rather than educational purposes, what would you decide?

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  • Is embedded programming closer to electrical engineering or software development?

    - by Jeremy Heiler
    I am being approached with a job for writing embedded C on micro controllers. At first I would have thought that embedding programming is to low on the software stack for me, but maybe I am thinking about it wrong. Normally I would have shrugged off an opportunity to write embedded code, as I don't consider myself an electrical engineer. Is this a bad assumption? Am I able to write interesting and useful software for embedded systems, or will I kick myself for dropping too low on the software stack? I went to school for computer science and really enjoyed writing a compiler, managing concurrent algorithms, designing data structures, and developing frameworks. However, I am currently employed as a Flex developer, which doesn't scream the interesting things I just described. (I currently deal with issues like: "this check box needs to be 4 pixels to the left" and "this date is formatted wrong".) I appreciate everyone's input. I know I have to make the decision for myself, I just would like some clarification on what it means to be a embedded programmer, and if it fits what I find to be interesting.

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  • Procurement and E-Business Suite Product Analyzers .. Can you use this tool to resolve your SR?

    - by LindaJ-Oracle
    Procurement and E-Business Suite Product Analyzers (Doc ID 1545562.1). Analyzers are Query/Read only tools with easy to read html output. The tools are delivered by EBS Support via My Oracle Support documents ids for ease of use. The Analyzer scripts are meant to be part of your Production maintenance program by your Sysadmin, or to designated end users. The result set is an easy to read html output that provides recommendations, solutions and early warnings to of items that should be reviewed and correct. Each analyzer can be ran on demand or scheduled for repeatability and emailed to critical reviewers. There are several Analyzers available for E-Business Suite Applications Technology Group, Financials, and Manufacturing including some of the following topics.  Review them all at (Doc ID 1545562.1). Workflow Concurrent Processing Clone Log Parser Utility (Rapid Clone) Invoices, Payments, Accounting, Suppliers and EBTax Validate Data before Period Close EBTax Setup Payables Trial Balance Internet Expenses AutoInvoice Post-Process ASCP Performance PO Approval iProcurement Items For the Procurement specific Analyzers access them directly at: R12 IP Item Analyzer Diagnostic Script (Doc ID 1586248.1) R12: PO Approval Analyzer Diagnostic Script (Doc ID 1525670.1)

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  • How to manage Agile developers working with traditional (serial) business persons?

    - by Riggy
    Good afternoon, My work environment has some problems. Our IT team is trying to be more agile, but we're not really getting buy-in from the business. They attend our daily stand-ups and sprint reviews, and they help with sprint planning, but then they turn around and do 4 months of requirements gathering for a project before moving forward with a (mostly) serial development style. The sprint goals are things like "get XX% closer to release". For the IT team, they've turned the Sprints into a sort of death march. We end a Sprint one day and start a new Sprint the very next day. There's no reflection or changes done between sprints, only during. Having never done any of the agile methodologies before, I haven't had a very pleasant introduction to them. So my questions are: 1) Should there be some time (perhaps a week or so) between sprints to do the reflection/introspection/changes/etc.? Or are back-to-back-to-back sprints the norm? 2) Is there any chance for survival for an agile team with no agile business counter-parts? If not, are there some transitional methodologies or even tips for moving the business towards an iterative if not necessarily agile mindset? 3) Should your entire team be on every sprint? We have almost 20 programmers on a single sprint but working on completely different projects (typically teams of 3-5, sometimes larger). Is it normal to have a single sprint or should we be trying to manage multiple independent sprints? Should we be trying to keep the multiple sprints in concurrent lockstep or should their timetables be allowed to overlap and be flexible? Any thoughts or advice is appreciated. This is my first time coming over from SO for a question, so please let me know if there are better ways to phrase these kinds of questions (faq was rather helpful, but still not sure I'm following it perfectly). Thanks!

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  • Information I need to know as a Java Developer [on hold]

    - by Woy
    I'm a java developer. I'm trying to get more knowledge to become a better programmer. I've listed a number of technologies to learn. Instead of what I've listed, what technologies would you suggest to learn as well for a Junior Java Developer? I realize, there's a lot of things to study. Java: - how a garbage collector works - resource management - network programming - TCP/IP HTTP - transactions, - consistency: interfaces, classes collections, hash codes, algorithms, comp. complexity concurrent programming: synchronizing, semafores steam management metability: thread-safety byte code manipulations, reflections, Aspect-Oriented Programming as base to understand frameworks such as Spring etc. Web stack: servlets, filters, socket programming Libraries: JDK, GWT, Apache Commons, Joda-Time, Dependency Injections: Spring, Nano Tools: IDE: very good knowledge - debugger - profiler - web analyzers: Wireshark, firebugs - unit testing SQL/Databases: Basics SELECTing columns from a table Aggregates Part 1: COUNT, SUM, MAX/MIN Aggregates Part 2: DISTINCT, GROUP BY, HAVING + Intermediate JOINs, ANSI-89 and ANSI-92 syntax + UNION vs UNION ALL x NULL handling: COALESCE & Native NULL handling Subqueries: IN, EXISTS, and inline views Subqueries: Correlated ITH syntax: Subquery Factoring/CTE Views Advanced Topics Functions, Stored Procedures, Packages Pivoting data: CASE & PIVOT syntax Hierarchical Queries Cursors: Implicit and Explicit Triggers Dynamic SQL Materialized Views Query Optimization: Indexes Query Optimization: Explain Plans Query Optimization: Profiling Data Modelling: Normal Forms, 1 through 3 Data Modelling: Primary & Foreign Keys Data Modelling: Table Constraints Data Modelling: Link/Corrollary Tables Full Text Searching XML Isolation Levels Entity Relationship Diagrams (ERDs), Logical and Physical Transactions: COMMIT, ROLLBACK, Error Handling

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  • Web Applications Desktop Integrator (WebADI) Feature for Install Base Mass Update in 12.1.3

    - by LuciaC
    Purpose The integration of WebADI technology with the Install Base Mass Update function is designed to make creation and update of bulk item instances much easier than in the past. What is it? WebADI is an Excel-based desktop application where users can download an Excel template with item instances pre-populated based on search criteria.  Users can create and update item instances in the Excel sheet and finally upload the Excel data using an "upload" option available in the Excel menu. On upload, the modified data will bulk upload to interface tables which are processed by an asynchronous concurrent program that users can monitor for the uploaded results. Advantage: This allows users to work in a disconnected Environment: session time outs can be avoided, as once a template is downloaded the user can work in a disconnected environment and once all updates are done the new input can be uploaded. Also the data can be saved for later update and upload. For more details review the following: R12.1.3 Install Base WebADI Mass Update Feature (Doc ID 1535936.1) How To Use Install Base WebADI Mass Update Feature In Release 12.1.3 (Doc ID 1536498.1).

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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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  • VMware Player 5.0 or VMware Workstation 9.0 after upgrade to Ubuntu 12.10

    The upgrade process Upgrading Ubuntu 12.04 to latest version 12.10 - aka Quantal Quetzal - is straight forward and you only need to follow the offical upgrade instructions. Short version on the console looks like this: sudo do-release-upgrade This will update the repository entries, and start the upgrade process. After some minutes or hours of download and installation, you have to reboot your system once to get the new kernel loaded. As time of writing, I'm on '3.5.0-17-generic'. And as with any modification of the kernel version, you have to compile the necessary kernel modules to get VMware Player or Workstation up and running. Usually, this happens the first time you try start your VMware software and that's it. Well, again not so this time. Getting the kernel patch Luckily, the community over VMware is very active and you can get a new kernel patch in the online forums here. Get the download and put in a folder have write permissions. Then you extract the archive on the console like so: tar -xjvf vmware9_kernel35_patch.tar.bz2 Then you change into the newly created folder: cd vmware9_kernel3.5_patch/ And you execute the available shell script as root (superuser) like so: sudo ./patch-modules_3.5.0.sh This will stop any running instances of VMware software, patches the source files and runs the compile process for your active environment. This might take some time depending on your machine, and once completed you can start VMware Player or Workstation as previously. In case that you are going to apply the patch again, the script will simply quit with the following output: /usr/lib/vmware/modules/source/.patched found. You have already patched your sources. Exiting You might remove the .patched file in case that you upgraded/changed your kernel and you need to apply the patch again. Disclaimer: The patch is "as-is" and the patcher is originally created by Artem S. Tashkinov, and later modified by An_tony. Please refer to the VMware forum in case of questions or problems. There are also patches available for older versions of VMware Player or Workstation.

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  • Dual monitor, permission issue

    - by cenna75
    I had a dual monitor configuration going on for quite some time. One day, after moving the computer to another location and reconnecting everything, it changed such that I saw everything in double (being very much sober), I think it's called the 'mirrors' config. Anyway, from there on, there was nothing to be done through the system settings gui to change it back, as it wouldn't allow me to save any modification. The error I get when clicking 'save' is : "Failed to create file /home/me/monitors.xml.xxxxxx. Permission denied", xxxx being a random code, changing everytime. However, I can save all the configurations I want just fine by using the terminal, in my case: xrandr --output DVI-I-1 --right-of VGA-1 So I do have a workaround and this is therefore a question more out of curiosity. What could possibly have changed to make it impossible to do it through the gui and still letting me change the config using xrandr without being root? I'm having a hard time believing it could have anything to do with disconnecting/reconnecting the monitors... Any idea? Thanks !

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  • SQL 2008/2005 Hosting :: Error - “Named Pipes Provider, error: 40 – Could not open a connection to SQL Server”

    - by mbridge
    When setting up a Microsoft Windows Server 2008 system, I went through the motions to set up IIS, MS SQL Server 2008, and Visual Studio 2010 to use as a test-bed. One of the immediate benefits of setting up such a system is that most development can be done remotely: MS SQL Server Management Studio, Visual Studio’s Web development suite, as well as file shares, remote desktop, etc, make for a great way to remotely develop in ‘pristine’ conditions. But there are drawbacks, too, such as needing to deal with firewall issues, not being able to penetrate past a router or the requirement of setting up a VPN. One of the problems I encountered when trying to remote into the MS SQL Server 2008 that I’d set up was the following error: Named Pipes Provider, error: 40 – Could not open a connection to SQL Server I followed the below steps, and was able to connect to the server after just a few moments of tinkering: 1. From the server in question, surf to this Microsoft article, and download and install the Firewall rules modification program. Never drop your firewall, even on a development machine, unless you have a really good reason to. 2. Launch SQL Server Configuration Manager. Navigate to SQL Server Network Configuration, then Protocols for your server name. Enable TCP/IP and Named Pipes by right-clicking and choosing Enable for each given Protocol Name. 3. Restart the SQL Server service from Services (or from command line, subsequently run “net stop mssqlserver” then “net start mssqlserver”. 4. Try your remote connection once more, and you should be able to connect. It’s not a terribly difficult concept, but one of the more challenging tasks developers face is dealing with environment setup. And while there is a certain blurred-line overlap between software development and server administration, sometimes the latter is daunting, especially given that you might set up only a handful of servers during your career.

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  • At what point does caching become necessary for a web application?

    - by Zaemz
    I'm considering the architecture for a web application. It's going to be a single page application that updates itself whenever the user selects different information on several forms that are available that are on the page. I was thinking that it shouldn't be good to rely on the user's browser to correctly interpret the information and update the view, so I'll send the user's choices to the server, and then get the data, send it back to the browser, and update the view. There's a table with 10,000 or so rows in a MySQL database that's going to be accessed pretty often, like once every 5-30 seconds for each user. I'm expecting 200-300 concurrent users at one time. I've read that a well designed relational database with simple queries are nothing for a RDBMS to handle, really, but I would still like to keep things quick for the client. Should this even be a concern for me at the moment? At what point would it be helpful to start using a separate caching service like Memcached or Redis, or would it even be necessary? I know that MySQL caches popular queries and the results, would this suffice?

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