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  • installing ubuntu on SSD

    - by kunal
    Going to install Ubuntu 10.10 on new intel x25M 80GB SSD. It will be fresh install. I have been googling for past few days and getting overwhelming articles/blogs/Q&As. One particularly very useful being: Optimize for SSD (I could not post other links as i dont have enough credits) But with so many suggestions and differences of opinions (on different links) this simple OS install process seems to be daunting task to me and I really want to stick with ubuntu (although have used for very short period of time). Can someone help me by answering few questions (yes they are repeated as i couldnt comprehend the answers elsewhere) which file system (ext2/3/4 or something else)? (consider SSD life) can it be changed after installation? should i partition the disk? (as we do in traditional HDD) for now, no plan of dual booting. Only ubuntu will live on scarce space of 80GB SSD. i have 2 GB RAM, should i still allocate swap space (if i dont allocate swap space, can i still hibernate the machine)? will swap space impact SSD life? should i consider putting additional 1GB RAM to avoid swap space? Linux experience - absolute novice intended usage - heavy browsing, programming, regular video/music and some other non-CPU/RAM-intensive programs. will backup big files to an external hard drive. laptop config - 3 yr old vaio, core2 duo, 2GB RAM Please pardon the repetition and i really appreciate anyone helping me getting started with ubuntu.

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  • Four Proven Advantages of Online Learning | Outside Cost, Accessibility or Flexibility

    - by Mohit Phogat
    Coursera believes that online courses complement and supplement traditional education (versus a common misconception online will “replace” traditional.) Our research shows that Coursera’s platform, when used concurrently with a traditional classroom setup, is ideal for “blended learning” (i.e., students watch lectures pre-class, then class-time focuses on interactive work and discussion.) Additionally, we agree with Brad Zomick of SkilledUp—an online learning aggregator—who acknowledges an online course “isn’t an alternative at all but rather a different path with its own rewards.” The advantages of Coursera and our apps for mobile were straightforward and conspicuous from the start: we’re free, open, and flexible to learners’ unique needs and style. Over the past two years, however, the evidence proves there are many more tangible benefits to open, online learning. In SkilledUp’s “The Advantages of Online Courses [Infographic]”–crafted from findings of leading educational research–four observations stand out from the overt characteristics: Speedier Learning - “Research shows that online students achieve same or better learning results in about half the time as those in traditional courses” More Active, Engaged & Motivated - Learners thrive “when working with coursework that is challenging but within their capacity to master.” Tangible Skill Building - with an “improved attitude toward learning” Better Teaching Quality - Courses are taught by experts, with various multimedia and cutting-edge technology, and “are usually better organized than traditional courses” This is only the beginning, Courserians! Everyday we hear your incredible stories on how open online courses enrich your lives and enhance your careers. Meanwhile we study the steady stream of scientific, big-data research proving their worth on a large-scale (such as UPenn’s latest research on the welcomed diversity in Coursera-hosted Wharton MBA courses.) Our motto “Learning without Limits” reminds us that open, online courses give tremendous opportunity to those that might not otherwise have access (or time, or money) to study at a high-caliber institution. Source: Coursera

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  • Implementing a multilanguage AI contest platform

    - by Alejandro Piad
    This is a followup to this question. To sum: I'm implementing an AI contest site, where each user may submit several AI implementations for different games. Think about Google AI Challenge but instead of just having a big event once a year, I would like it more on a league fashion, with all virtual players playing with each other every some close period of time. I want to support as many programming languages as possible. I've seen that contest sites (like codeforces) ask you to submit a source code and interact through stdin and stdout. The first question is: what is the best way of supporting multiple languages? As I see it, I can either ask people to upload some binary/script, and interact either through stdin/*stdout*, or sockets, or the file system; or ask people to submit source code, and wrap it with whatever is necessary for the interaction. I would like to skip the need to compile the code by myself (in the server, I mean), but I am willing to do it if its the "best" choice. I need to comunicate virtual players with each other, or even better, with some intermediary arbiter. The second question is regarding security. If I'm going to be running user code in my server, I want to ensure strict security conditions, like no file system access, no networking, etc. Otherwise it would be a safe heaven for hackers. I will be implementing the engine/arbiter in .NET. I would like to support at least C#, C++, Java and Python for the user's implementations. I'm willing to write interfaces for each of these languages to simplify the user interaction with the system. Thanks in advance.

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  • Should I use procedural animation?

    - by user712092
    I have started to make a fantasy 3d fps swordplay game and I want to add animations. I don't want to animate everything by hand because it would take a lot of time, so I decided to use procedural animation. I would certainly use IK (starting with simple reaching an object with hand ...). I also assume procedural generation of animations will make less animations to do by hand (I can blend animations ...). I want also to have a planner for animation which would simplify complex animations; those which can be split to a sequence - run and then jump, jump and then roll - or which are separable - legs running and torso swinging with sword -. I want for example a character to chop a head of a big troll. If troll crouches character would just chop his head off, if it is standing he would climb on a troll. I know that I would have to describe the state ("troll is low", "troll is high", "chop troll head" ..) which would imply what regions animation will be in (if there is a gap between them character would jump), which would imply what places character can have some of legs and hands or would choose an predefined animation. My main goal is simplicity of coding, but I want my game to be looking cool also. Is it worthy to use procedural animation or does it make more troubles that it solves? (there can be lot of twiddling ...) I am using Blender Game Engine (therefore Python for scripting, and Bullet Physics).

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  • We've Been Busy: World Tour 2010

    - by [email protected]
    By Brian Dayton on March 11, 2010 11:17 PM Right after Oracle OpenWorld 2009 we went right into planning for our 2010 World Tour. An ambitious 90+ city tour visiting cities on every continent. The Oracle Applications Strategy Update Tour started January 19th and is in full swing right now. We've put some heavy hitters on the road. If you didn't get a chance to see Steve Miranda, Senior Vice President of Oracle Application Development in Tokyo, Anthony Lye, Senior Vice President of Oracle CRM Development in New Delhi or Sonny Singh, Senior Vice President of Oracle Industries Business Unit in Stockholm don't worry...we're not done yet. The theme, Smart Strategies: Your Roadmap to the Future is a nod to the fact that everyone needs to be smart about what's going on in their business and industry right now. But just as important---how to make sure that you're on the course to where you need to be down the road. Get the big picture and key trends in "The New Normal" of today's business climate and drill down and find out about the latest and greatest innovations in Oracle Applications. Check out http://www.oracle.com/events/applicationstour/index.html for an upcoming tour date near you. Pictures, feedback, summaries and learnings from the tour to come soon.

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  • Why is it that software is still easily pirated today?

    - by mohabitar
    I've always been curious about this. Now I wouldn't call myself a programmer yet, but I'm learning, so maybe the answer to this is obvious. It just seems a little hard to believe that with all of our technological advances and the billions of dollars spent on engineering the most unbelievable and mind-blowing software, we still have no other means of protecting against piracy then a "serial number/activation key". I'm sure a ton of money, maybe even billions, went into creating Windows 7 or Office and even Snow Leopard, yet I can get it for free in less than 20 minutes. Same for all of Adobe's products, which are probably the easiest. I guess my question is: can there exist a fool proof and hack proof method of protecting your software against piracy? If not realistically, how about theoretically possible? Or no matter what mechanisms these companies deploy, hackers can always find a way around it? EDIT: So apparently, the answer is no. There's pretty much no way. And so I'm sure these big companies have realized this as well. Should they adopt another sales model rather than charging a crapload for their software (I know its justified and they put a lot of hard work into their software, but its still a lot of money). Are there any alternative solutions that will benefit both the company and the user (i.e. if you purchase our product, we'll apply $X dollars to your account that will apply to future purchases from our company)?

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  • Spotlight on an ACE: Edwin Biemond

    - by jeckels
    Edwin Biemond is an active member of the ACE community, having worked with Oracle's development tooling and database technologies since 1997. Since then, Edwin has become an expert in many of Oracle's middleware technologies as well, including WebLogic and SOA. In fact, Edwin has become so prolfic that he was named the Java Developer of the Year in 2009. Edwin hails from the Netherlands, where he is an architect at the company Amis, and is also a co-author of the OSB Development Cookbook. He's a proven expert in ADF, JSF, messaging (Edifact / ebXML), Enterprise Service Bus, web services and tuning of application servers and databases. Recently, Edwin posted a blog on the road map of WebLogic 12c, going over salient features and what the future looks like for Fusion Middleware and the Application Server areas - it's well worth a read, so give it a look. A snippet: WebLogic 12.1.3 will be the first version for many FMW 12c products like Oracle SOA Suite 12c and probably come in one big jar. 12.1.3 & 12.1.4 will add extra features and improvements to Elastic JMS & Dynamic Clusters. Elastic JMS in 12.1.3 will support Server Migration so you can’t lose any JMS messages. In 12.1.4, Dynamic Clusters will have support for auto-scaling based on thresholds based on user-defined metrics. WebLogic 12.1.4 will also have an API to control the Dynamic Clusters, this way we can easily program when to stop, start or remove nodes from a dynamic cluster. Further, Edwin is hosting a session on getting your FMW environment up and running in less than 10 minutes using popular tooling to configure and manage the many FMW components you have in your technology stack. Register now for this virtual developer day to see more. We thank Edwin for his commitment to being an ACE, his work on his blog, his social media publishing and his overall commitment to helping other technologists be even more successful with Oracle products. Follow Edwin on his blog, Twitter, Facebook, LinkedIn, or read his ACE Profile

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  • September OTN Member Offers

    - by Cassandra Clark - OTN
    Oracle OpenWolrd and JavaOne are coming....so the OTN team is knee deep in planning the OTN Lounges that will be at each event this year (more info in another post soon), but we managed to work with our partners to offer a nice BIG list of NEW offers for September.  Visit Oracle Technology Network Member Discount page for codes and links to these great offers! Oracle Press Oracle Technology Network members get 40% off the newest Oracle Press title, Oracle Exalogic Elastic Cloud Handbook by Tom Plunkett! Mike Murach & Associates, Inc. Get 30% off and sample chapter of Murach’s SQL Server 2012 for Developers by Bryan Syverson and Joel Murach Manning - 41% off titles below and sample chapter of each. Making Java Groovy OCA Java SE 7 Programmer I Certification Guide Apress - Get 30% off on apress.com on Java 7 Recipes A Problem-Solution Approach Safari Books Online - OTN members get 30 days of free access + 20% off unlimited access to Safari Books Online for 6 months. Safari Books Online offers subscription access to more than 24,000 books and training videos about technology, digital media, business management and professional development from leading publishers such as Oracle Press, O'Reilly Media, Que, Addison-Wesley, Wrox, Cisco Press, Microsoft Press, McGraw Hill, Wiley, Apress, Adobe Press and many others. Already a customer? Come see us at Oracle OpenWorld (booth 537) or JavaOne (5110) and mention this to get a shirt!

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  • Too much I/O in the morning ?

    - by steveh99999
    Interesting little improvement on a SQL 2005 system I encountered recently….. Some background - this system had a fairly ‘traditional OLTP’ workload ie  heavily used during day – till around 9pm, then had a batch window for several hours, then not much activity in the early hours of the day, until normal workload resumed the following morning. Using perfmon, I noticed that every morning, we would see a big spike in SQL Server I/O when the application started to be used... As it was 2005 I decided to look at what tables were in cache before and after the overnight batch processing ran… ( using DMV equivalent of dbcc memusage that I posted earlier). Here’s what I saw :-     So, contents of data cache split fairly evenly between my 'important/heavily used' tables.   After this:- some application batch processing,backups, DBCC checks and reindexes were run.  A fairly standard batch I'd suggest. Cache contents then looked like this :- Hmmmm – most of cache is now being used by a table I’ve described as ‘unimportant’. Why ? Well, that table was the last to be reindexed…. purely due to luck, as  the reindexing stored procedure performing a loop in alphabetical order through all application tables...  When the application starts to be used again – all this ‘unimportant’ data has to be replaced in cache by data that is heavily used… So, we changed the overnight reindex scripts –  the most heavily accessed tables are now the last to be reindexed. Obvious really, but we did see a significant reduction in early-morning I/O after changing the order of our reindexing.  

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  • The Middle of Every Project

    - by andrew.sparks
    I read a quote somewhere “The middle of every successful project looks like a mess.” or something to that effect. I suppose the projects where the beginning, middle and end are a mess are the ones you need to watch out for. Right now we are in ramp up of the maintenance/support teams at a big project in the Nordics. We are facing a year of mixed mode operations, where we have production operations and the phased rollout to new locations in parallel. The support team supports, and the deployment team deploys. As usual the assumption right up to about a month or so before initial go-live was that the deployment team would carry the support. Not! Consequently we had a last minute scramble over the Christmas/New Year to fire up a support/maintenance team. While it is a bit messy and not perfect – the quality of the mess (I mean scramble) is not so bad. Weekly operational review with the operational delivery managers, written issue lists and assigned actions, candid discussions getting the problems on the table and documented, issues getting solved and moved off the table. So while the middle of a project might look like a mess (even the start) it is methodical use of project management tools of checklists and scheduled communication points that are helping us navigate out of the mess and bring it all under control.

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  • Inheriting projects - General Rules?

    - by pspahn
    This is an area of discussion I have long been curious about, but overall, I generally lack the experience to give myself an answer that I would fully trust. We've all been there, a new client shows up with a half-complete project they are looking to finish and launch. For whatever reason, they fired their previous developer, and it's now up to you to save the day. I am just finishing up a code review for a new client, and in my estimation is would be better to scrap what the previous developers built since and start from scratch. There's a ton of reasons why I am leaning toward this way, but it still makes me nervous since the client isn't going to want to hear "those last guys built you a big turd, and I can either polish it, or throw it in the trash". What are your general rules for accepting these projects? How do you determine whether it will be better to start from scratch or continue with the existing code base? What other extra steps might you take to help control client expectations, since the previous developer may have inflated those expectations beyond a reasonable level? Any other general advice?

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  • Partial upgrade on 12.04, how to stop nagging after locking to a working NVIDIA & xorg

    - by alsk
    How to stop the upgrade manager from offering updates and upgrades that potentially would harm my working 2D and 3D graphics? Finally, I got 12.04 working as it should: with nvidia-173 drivers by downgrading xorg and locking the version: On my 32-bit system on Athlon64, with (Albatron) NVIDIA GeForce FX5700XT, locked (/pinned) to xorg 1:7.6-7ubuntu7, xserver-xorg-core 2:11.1-0obuntu10.07, nvidia-173 173.14.35-0ubuntu0.2? An annoying thing left is that every time the updates are checked, I get warning of partial updates, and ambiguous options of "partial update" and "close". Ambiguous in that sense that if I click close, I will get option to update a few packages, which has been OK, while "partial update" would like to update my kernel to 3.2, alter xorg, remove nvidia-173 etc., and update mesa etc. This is not what I call appropriate, after locking XORG and NVIDIA drivers to working ones. One may say according to package management logic it may be correct, but to me as an user it makes little sense. Last Ubuntu that worked without big mess for me was 10.10, hence I will not put 12.10 to my "production" system, until I can be sure it will not trash the system again. P.S. Is there a recommended way to keep NVIDIA GeForce FX working with 3D on Ubuntu... in future?

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  • Atelier gratuit : Découvrir la solution d'exploration de données structuré et non structuré

    - by David lefranc
    Explorer et découvrir l’information… Nous vous proposons un atelier découverte pour vous permettre d’explorer toute type de données grace à la solution Oracle Endeca Information Discovery. Quand : 7 Décembre 2012 De 9h30 à 12h30  Lieu : Oracle 15 Boulevard Charles de gaulle 92715 Colombes Pour s'inscrire : [email protected] Réalisé pour des utilisateurs métiers, cet atelier vous permettera en une demi journée , de découvrir Oracle Endeca Information Discovery afin de : Comprendre et explorer toute information venant de différents horizons ( Big Data, réseaux sociaux, forums, sondages, blogs..) Découvrir en quoi et comment OEID est un complément à des solutions de BI classiques Par une navigation simple et rapide, vous découvrirez combien il est facile de trouver des réponses à des questions imprévues en utilisant OEID sans formation préalable. Utilisez la recherche et la navigation guidée pour voir comment les informations structurées et non structurées peuvent être rapidement réunies pour dégager la valeur cachée. Explorer toutes vos données dans n'importe quel format et à partir de n'importe quelle source, y compris les médias sociaux, documents, fichiers,…. Pouvoir découvrir et explorer vos données sans référentiel pour permettre aux utilisateurs d’être autonome et d’analyser leurs propres données de manière rapide Élaborer une stratégie visant à accroître la valeur des données de l'entreprise tout en réduisant le coût total de possession Découvrez l'incroyable performance d’ Endeca sur Oracle Exalytics la machine In Memory Agenda Après une introduction sur la solution Oracle information Endeca, suivi d’un atelier, vous verrez comment il est facile de: Utiliser la navigation guidée et le moteur de recherche pour explorer les données structurées et non structurées intégrer rapidement les nouvelles sources de données comme les médias sociaux Construire de nouvelles interfaces utilisateur tout en découvrant l’information répondre rapidement aux besoins changeants des entreprises et des environnements de données Quand Lieu 7 Décembre 2012 De 9h30 à 12h30 Oracle 15 Boulevard Charles de gaulle 92715 Colombes

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  • What's the best algorithm for... [closed]

    - by Paska
    Hi programmers! Today come out a little problem. I have an array of coordinates (latitude and longitude) maded in this way: [0] = "45.01234,9.12345" [1] = "46.11111,9.12345" [2] = "47.22222,9.98765" [...] etc In a loop, convert these coordinates in meters (UTM northing / UTM easting) and after that i convert these coords in pixel (X / Y) on screen (the output device is an iphone) to draw a route line on a custom map. [0] = "512335.00000,502333.666666" [...] etc The returning pixel are passed to a method that draw a line on screen (simulating a route calculation). [0] = "20,30" [1] = "21,31" [2] = "25,40" [...] etc As coordinate (lat/lon) are too many, i need to truncate lat/lon array eliminating the values that doesn't fill in the map bound (the visible part of map on screen). Map bounds are 2 couple of coords lat/lon, upper left and lower right. Now, what is the best way to loop on this array (NOT SORTED) and check if a value is or not in bound and after remove the value that is outside? To return a clean array that contains only the coords visible on screen? Note: the coords array is a very big array. 4000/5000 couple of items. This is a method that should be looped every drag or zoom. Anyone have an idea to optimize search and controls in this array? many thanks, A

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  • Strange behavior on Gnome after update on from 13.04 to 13.10

    - by WayneBrady
    I made an automatic update on my Ubuntu 13.10 (from 13.04) system today. Since this point of time, I am in really big trouble. I use a VNC server with Gnome classic, after the update my Gnome was gone. So i tried everything. Checked the xstartup file of vncserver. Right now I reached a point where I can't find the answer. The logfile says that gnome-session-fallback is missing, even directly after I installed it with apt-get (tried it serveral times, installing, uninstalling and so on). I have no chance to use it as you can see in this terminal copy: root@ip-xxx:~/.vnc# apt-get install gnome-session-fallback Reading package lists... Done Building dependency tree Reading state information... Done The following NEW packages will be installed: gnome-session-fallback 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. Need to get 0 B/2,914 B of archives. After this operation, 247 kB of additional disk space will be used. Selecting previously unselected package gnome-session-fallback. (Reading database ... 210977 files and directories currently installed.) Unpacking gnome-session-fallback (from .../gnome-session-fallback_1%3a3.6.2-0ubuntu15_all.deb) ... Setting up gnome-session-fallback (1:3.6.2-0ubuntu15) ... root@ip-xxx:~/.vnc# gnome-session-fallback The program 'gnome-session-fallback' is currently not installed. You can install it by typing: apt-get install gnome-session-fallback If you have some idea, please give me a hint... Thank you!

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  • Join Oracle Database at Microsoft TechEd next week.

    - by Mandy Ho
    For the past nine years, Oracle has been a proud sponsor of Microsoft TechEd. TechEd is Mircosoft's premier technology conference for IT professionals and developers. This year, Oracle will demonstrate its latest database software for MS Windows, including Oracle Database 11g Enterprise and Express editions, TimesTen and MySQL.  Developers can learn how to develop .Net applications for the Oracle Database using the latest technologies, such as Entity Framework, LINQ and WCF Data Services. Attendees can also learn the new MySQL features enabling rapid installation, GUI Based application design, backup & recovery and much more within a Windows environment. Oracle will have a BOF (Birds of a Feather Session) on Tuesday, June 12, from 3:15 to 4:30. The topic will be Big Data: The Next Frontier for Innovation, Competition and Productivity. Otherwise you can visit Oracle everyday during the expo hours from Mon, June 11 to Thursday, June 14 at our booth #613. Talk to experts on TimesTen and MySQL on Windows and .NET. Also, we will have our 3D interactive demos on Oracle's engineered systems showing off Oracle Exadata, Database Appliance and more. Visit  http://northamerica.msteched.com/ for more information. 

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  • C++ and function pointers assessment: lack of inspiration

    - by OlivierDofus
    I've got an assessment to give to my students. It's about C++ and function pointers. Their skill is middle: it the first year of a programming school after bachelor. To give you something precise, here's a sample of a solution of one of 3 exercices they had to do in 30 minutes (the question was: "here's a version of a code that could be written with function pointers, write down the same thing but with function pointers"): typedef void (*fcPtr) (istream &); fcPtr ArrayFct [] = { Delete , Insert, Swap, Move }; void HandleCmd (const string && Cmd) { string AvalaibleCommands ("DISM"); string::size_type Pos; istringstream Flux (Cmd); char CodeOp; Flux >> CodeOp; Pos = AvalaibleCommands.find (toupper (CodeOp)); if (Pos != string::npos) { ArrayFct [Pos](Flux); } } Any idea where I could find some inspiration? Some of the students have understood the principles, even though it's very hard for them to write C++ code. I know them, I know they're clever, and I'm pretty sure they should be very good project managers. So, writing C++ code is not that important after all. Understanding is the most important part (IMHO). I'm wondering about maybe break the habits, and give half of the questions about the principle, or even better, give some sample in other language and ask them why it's better to use function pointers instead of classical programming (usually a big switch case). Any idea where I could look? Find some inspiration?

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  • Why isn't Java used for modern web application development?

    - by Cliff
    As a professional Java programmer, I've been trying to understand - why the hate toward Java for modern web applications? I've noticed a trend that out of modern day web startups, a relatively small percentage of them appears to be using Java (compared to Java's overall popularity). When I've asked a few about this, I've typically received a response like, "I hate Java with a passion." But no one really seems to be able to give a definitive answer. I've also heard this same web startup community refer negatively to Java developers - more or less implying that they are slow, not creative, old. As a result, I've spent time working to pick up Ruby/Rails, basically to find out what I'm missing. But I can't help thinking to myself, "I could do this much faster if I were using Java," primarily due to my relative experience levels. But also because I haven't seen anything critical "missing" from Java, preventing me from building the same application. Which brings me to my question(s): Why is Java not being used in modern web applications? Is it a weakness of the language? Is it an unfair stereotype of Java because it's been around so long (it's been unfairly associated with its older technologies, and doesn't receive recognition for its "modern" capabilities)? Is the negative stereotype of Java developers too strong? (Java is just no longer "cool") Are applications written in other languages really faster to build, easier to maintain, and do they perform better? Is Java only used by big companies who are too slow to adapt to a new language?

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  • Simplify Your Code with LINQ

    - by dwahlin
    I’m a big fan of LINQ and use it wherever I can to minimize code and make applications easier to maintain overall. I was going through a code file today refactoring it based on suggestions provided by Resharper and came across the following method: private List<string> FilterTokens(List<string> tokens) { var cleanedTokens = new List<string>(); for (int i = 0; i < tokens.Count; i++) { string token = tokens[i]; if (token != null) { cleanedTokens.Add(token); } } return cleanedTokens; }   In looking through the code I didn’t see anything wrong but Resharper was suggesting that I convert it to a LINQ expression: In thinking about it more the suggestion made complete sense because I simply wanted to add all non-null token values into a List<string> anyway. After following through with the Resharper suggestion the code changed to the following. Much, much cleaner and yet another example of why LINQ (and Resharper) rules: private List<string> FilterTokens(IEnumerable<string> tokens) { return tokens.Where(token => token != null).ToList(); }

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  • Developing Schema Compare for Oracle (Part 2): Dependencies

    - by Simon Cooper
    In developing Schema Compare for Oracle, one of the issues we came across was the size of the databases. As detailed in my last blog post, we had to allow schema pre-filtering due to the number of objects in a standard Oracle database. Unfortunately, this leads to some quite tricky situations regarding object dependencies. This post explains how we deal with these dependencies. 1. Cross-schema dependencies Say, in the following database, you're populating SchemaA, and synchronizing SchemaA.Table1: SOURCE   TARGET CREATE TABLE SchemaA.Table1 ( Col1 NUMBER REFERENCES SchemaB.Table1(Col1));   CREATE TABLE SchemaA.Table1 ( Col1 VARCHAR2(100) REFERENCES SchemaB.Table1(Col1)); CREATE TABLE SchemaB.Table1 ( Col1 NUMBER PRIMARY KEY);   CREATE TABLE SchemaB.Table1 ( Col1 VARCHAR2(100) PRIMARY KEY); We need to do a rebuild of SchemaA.Table1 to change Col1 from a VARCHAR2(100) to a NUMBER. This consists of: Creating a table with the new schema Inserting data from the old table to the new table, with appropriate conversion functions (in this case, TO_NUMBER) Dropping the old table Rename new table to same name as old table Unfortunately, in this situation, the rebuild will fail at step 1, as we're trying to create a NUMBER column with a foreign key reference to a VARCHAR2(100) column. As we're only populating SchemaA, the naive implementation of the object population prefiltering (sticking a WHERE owner = 'SCHEMAA' on all the data dictionary queries) will generate an incorrect sync script. What we actually have to do is: Drop foreign key constraint on SchemaA.Table1 Rebuild SchemaB.Table1 Rebuild SchemaA.Table1, adding the foreign key constraint to the new table This means that in order to generate a correct synchronization script for SchemaA.Table1 we have to know what SchemaB.Table1 is, and that it also needs to be rebuilt to successfully rebuild SchemaA.Table1. SchemaB isn't the schema that the user wants to synchronize, but we still have to load the table and column information for SchemaB.Table1 the same way as any table in SchemaA. Fortunately, Oracle provides (mostly) complete dependency information in the dictionary views. Before we actually read the information on all the tables and columns in the database, we can get dependency information on all the objects that are either pointed at by objects in the schemas we’re populating, or point to objects in the schemas we’re populating (think about what would happen if SchemaB was being explicitly populated instead), with a suitable query on all_constraints (for foreign key relationships) and all_dependencies (for most other types of dependencies eg a function using another function). The extra objects found can then be included in the actual object population, and the sync wizard then has enough information to figure out the right thing to do when we get to actually synchronize the objects. Unfortunately, this isn’t enough. 2. Dependency chains The solution above will only get the immediate dependencies of objects in populated schemas. What if there’s a chain of dependencies? A.tbl1 -> B.tbl1 -> C.tbl1 -> D.tbl1 If we’re only populating SchemaA, the implementation above will only include B.tbl1 in the dependent objects list, whereas we might need to know about C.tbl1 and D.tbl1 as well, in order to ensure a modification on A.tbl1 can succeed. What we actually need is a graph traversal on the dependency graph that all_dependencies represents. Fortunately, we don’t have to read all the database dependency information from the server and run the graph traversal on the client computer, as Oracle provides a method of doing this in SQL – CONNECT BY. So, we can put all the dependencies we want to include together in big bag with UNION ALL, then run a SELECT ... CONNECT BY on it, starting with objects in the schema we’re populating. We should end up with all the objects that might be affected by modifications in the initial schema we’re populating. Good solution? Well, no. For one thing, it’s sloooooow. all_dependencies, on my test databases, has got over 110,000 rows in it, and the entire query, for which Oracle was creating a temporary table to hold the big bag of graph edges, was often taking upwards of two minutes. This is too long, and would only get worse for large databases. But it had some more fundamental problems than just performance. 3. Comparison dependencies Consider the following schema: SOURCE   TARGET CREATE TABLE SchemaA.Table1 ( Col1 NUMBER REFERENCES SchemaB.Table1(col1));   CREATE TABLE SchemaA.Table1 ( Col1 VARCHAR2(100)); CREATE TABLE SchemaB.Table1 ( Col1 NUMBER PRIMARY KEY);   CREATE TABLE SchemaB.Table1 ( Col1 VARCHAR2(100)); What will happen if we used the dependency algorithm above on the source & target database? Well, SchemaA.Table1 has a foreign key reference to SchemaB.Table1, so that will be included in the source database population. On the target, SchemaA.Table1 has no such reference. Therefore SchemaB.Table1 will not be included in the target database population. In the resulting comparison of the two objects models, what you will end up with is: SOURCE  TARGET SchemaA.Table1 -> SchemaA.Table1 SchemaB.Table1 -> (no object exists) When this comparison is synchronized, we will see that SchemaB.Table1 does not exist, so we will try the following sequence of actions: Create SchemaB.Table1 Rebuild SchemaA.Table1, with foreign key to SchemaB.Table1 Oops. Because the dependencies are only followed within a single database, we’ve tried to create an object that already exists. To fix this we can include any objects found as dependencies in the source or target databases in the object population of both databases. SchemaB.Table1 will then be included in the target database population, and we won’t try and create objects that already exist. All good? Well, consider the following schema (again, only explicitly populating SchemaA, and synchronizing SchemaA.Table1): SOURCE   TARGET CREATE TABLE SchemaA.Table1 ( Col1 NUMBER REFERENCES SchemaB.Table1(col1));   CREATE TABLE SchemaA.Table1 ( Col1 VARCHAR2(100)); CREATE TABLE SchemaB.Table1 ( Col1 NUMBER PRIMARY KEY);   CREATE TABLE SchemaB.Table1 ( Col1 VARCHAR2(100) PRIMARY KEY); CREATE TABLE SchemaC.Table1 ( Col1 NUMBER);   CREATE TABLE SchemaC.Table1 ( Col1 VARCHAR2(100) REFERENCES SchemaB.Table1); Although we’re now including SchemaB.Table1 on both sides of the comparison, there’s a third table (SchemaC.Table1) that we don’t know about that will cause the rebuild of SchemaB.Table1 to fail if we try and synchronize SchemaA.Table1. That’s because we’re only running the dependency query on the schemas we’re explicitly populating; to solve this issue, we would have to run the dependency query again, but this time starting the graph traversal from the objects found in the other database. Furthermore, this dependency chain could be arbitrarily extended.This leads us to the following algorithm for finding all the dependencies of a comparison: Find initial dependencies of schemas the user has selected to compare on the source and target Include these objects in both the source and target object populations Run the dependency query on the source, starting with the objects found as dependents on the target, and vice versa Repeat 2 & 3 until no more objects are found For the schema above, this will result in the following sequence of actions: Find initial dependenciesSchemaA.Table1 -> SchemaB.Table1 found on sourceNo objects found on target Include objects in both source and targetSchemaB.Table1 included in source and target Run dependency query, starting with found objectsNo objects to start with on sourceSchemaB.Table1 -> SchemaC.Table1 found on target Include objects in both source and targetSchemaC.Table1 included in source and target Run dependency query on found objectsNo objects found in sourceNo objects to start with in target Stop This will ensure that we include all the necessary objects to make any synchronization work. However, there is still the issue of query performance; the CONNECT BY on the entire database dependency graph is still too slow. After much sitting down and drawing complicated diagrams, we decided to move the graph traversal algorithm from the server onto the client (which turned out to run much faster on the client than on the server); and to ensure we don’t read the entire dependency graph onto the client we also pull the graph across in bits – we start off with dependency edges involving schemas selected for explicit population, and whenever the graph traversal comes across a dependency reference to a schema we don’t yet know about a thunk is hit that pulls in the dependency information for that schema from the database. We continue passing more dependent objects back and forth between the source and target until no more dependency references are found. This gives us the list of all the extra objects to populate in the source and target, and object population can then proceed. 4. Object blacklists and fast dependencies When we tested this solution, we were puzzled in that in some of our databases most of the system schemas (WMSYS, ORDSYS, EXFSYS, XDB, etc) were being pulled in, and this was increasing the database registration and comparison time quite significantly. After debugging, we discovered that the culprits were database tables that used one of the Oracle PL/SQL types (eg the SDO_GEOMETRY spatial type). These were creating a dependency chain from the database tables we were populating to the system schemas, and hence pulling in most of the system objects in that schema. To solve this we introduced blacklists of objects we wouldn’t follow any dependency chain through. As well as the Oracle-supplied PL/SQL types (MDSYS.SDO_GEOMETRY, ORDSYS.SI_COLOR, among others) we also decided to blacklist the entire PUBLIC and SYS schemas, as any references to those would likely lead to a blow up in the dependency graph that would massively increase the database registration time, and could result in the client running out of memory. Even with these improvements, each dependency query was taking upwards of a minute. We discovered from Oracle execution plans that there were some columns, with dependency information we required, that were querying system tables with no indexes on them! To cut a long story short, running the following query: SELECT * FROM all_tab_cols WHERE data_type_owner = ‘XDB’; results in a full table scan of the SYS.COL$ system table! This single clause was responsible for over half the execution time of the dependency query. Hence, the ‘Ignore slow dependencies’ option was born – not querying this and a couple of similar clauses to drastically speed up the dependency query execution time, at the expense of producing incorrect sync scripts in rare edge cases. Needless to say, along with the sync script action ordering, the dependency code in the database registration is one of the most complicated and most rewritten parts of the Schema Compare for Oracle engine. The beta of Schema Compare for Oracle is out now; if you find a bug in it, please do tell us so we can get it fixed!

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  • Python or Ruby in 2011.

    - by Sleeper Smith
    What I'm really asking is, in the current services and technologies provided, which is a more "useful" language? Which one has more opportunity? Some background info first. I'm a .net C# dev for 5 years. Having done a few projects on Amazon AWS, I'm looking to start a few projects of my own. But Azure's too expensive, and AWS has too much management overhead. My current choice is Google App Engine and Python. Logical enough. But what I want to ask here is this: In Linux world, which is more useful? Recently heard about Heroku for Ruby. How viable is this? Looking at the pricing model indicates that it's more expensive. Which one has more up-to-date and exciting open source projects? For instance Trac is just plain out dated compared to Redmine. One of the big reason pulling me for Ruby is Redmine. Implementations? IronPython/IronRuby/JRuby etc etc. Which one is more standardised and more implementation agnostic? Which one is easier to port between Windows/Linux? Anyway, your input and thoughts are greatly appreciated. thanks.

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  • JEE frameworks, a road map to learn? and should I learn them?

    - by vibhor
    Background Information I have been into programming since past 1 years professionally, my day to day work includes writing BIRT reports, designing and validating forms using JEE (struts/spring, hibernate). I don't have a comp Sci 4 year degree (Electronics), so I have very Limited experience in comp Sci. Question JEE frameworks (struts1/2, spring, hibernate etc) are hot nowadays, however java world have a tendency of building A4j, B4J... mayway4J kind of stuff (and I am tired of it). AFAIK, frameworks are nothing but bunch of XML config files and hundreds of classes built to cram (by developer). And sooner then later a new framework come into picture that says I am the best among all. So My Question is - 1.What will you do to learn a framework (many frameworks) considering that it can be obsolete till you'll be master in it (Learning frameworks can take significant amount of time)? 2.Considering early into your career, will you give a damn that how well someone knows framework (knowing frame work is important but still..) and why/how should I learn a framework knowing I have to (un)learn it in order to learn other one (plenty of of 4Js....)? I am just trying to get a big picture, that, if you're in place of me, what would be your learning/cramming strategy (Road map)? I am not intended to start a holy war between A versus B, (frameworks are more or less essential).

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  • 2-D Codes in Retail

    - by David Dorf
    The UPC you find on packaging is a one-dimensional barcode that's been in use, in one form or another, since the 1970s. While its a good symbology to encode numbers like a product identifier, its not really big enough to hold much more. It also requires a barcode scanner (like those connected to the POS), although iPhone apps like RedLaser have proved a mobile camera can be made to work in many situations. The next generation barcodes are two-dimensional and therefore capable of holding much more information as well as being more conducive to cameras. The most popular format is the QR Code, widely used in Japan because almost every mobile phone has a built-in reader. A typical use for QR Codes is to embed a URL so that that a mobile phone can quickly navigate to the specified web page. QR Codes can be found on posters, billboards, catalogs, and circulars. Speaking of which, Best Buy recently put a QR code in their circular as shown below. If fact, they even updated their iPhone application to include a QR Code reader. I was able to scan the barcode above right from the screen with my iPhone without issues, even though its fairly small in this image. Clearly they are planning to incorporate more QR Codes in their stores and advertising. If you haven't seen QR Codes before, you're not looking hard enough. They are around and will continue to spread.

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  • Where to store global enterprise properties?

    - by shylynx
    I'm faced with a crowd of java applications, which need different global enterprise wide properties for operation, for example: hostname of the central RDBMS, hostname and location of the central self-service portal, host location of central LDAP, host location of central mail server etc. Formally we build each application with a properties file, where all this properties are definied. But that's a very bad solution, because if the hostname of the mail server changes, we need to change the properties files for each application and deploy all applications again. Our idea is to centralize this properties, so that each application can ask for each property at runtime, for example: Idea: Put the properties file to an easy accessible file share. So if we need to change a property, each application uses the new properties. Idea: Put the properties to database. Main disadvantage: we need a dependency to database client libraries for each application. Idea: Put all applications into one big application server, that provides system properties for each application. Main disadvantage: needs deployment of each application to one application server. But that isn't a realistic scenario. Idea: Webservice that provides global enterprise wide properties. Main disadvantage: not very secure, because some properties are passwords or user credentials. What other alternatives are recommended? What is state of the art?

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  • How to get initial API right using TDD?

    - by Vytautas Mackonis
    This might be a rather silly question as I am at my first attempts at TDD. I loved the sense of confidence it brings and generally better structure of my code but when I started to apply it on something bigger than one-class toy examples, I ran into difficulties. Suppose, you are writing a library of sorts. You know what it has to do, you know a general way of how it is supposed to be implemented (architecture wise), but you keep "discovering" that you need to make changes to your public API as you code. Perhaps you need to transform this private method into strategy pattern (and now need to pass a mocked strategy in your tests), perhaps you misplaced a responsibility here and there and split an existing class. When you are improving upon existing code, TDD seems a really good fit, but when you are writing everything from scratch, the API you write tests for is a bit "blurry" unless you do a big design up front. What do you do when you already have 30 tests on the method that had its signature (and for that part, behavior) changed? That is a lot of tests to change once they add up.

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