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• VirtualBox 3.2 is released! A Red Letter Day?

  - by Fat Bloke

  Big news today! A new release of VirtualBox packed full of innovation and improvements. Over the next few weeks we'll take a closer look at some of these new features in a lot more depth, but today we'll whet your appetite with the headline descriptions. To start with, we should point out that this is the first Oracle-branded version which makes today a real Red-letter day ;-)  Oracle VM VirtualBox 3.2 Version 3.2 moves VirtualBox forward in 3 main areas ( handily, all beginning with "P" ) : performance, power and supported guest operating system platforms.  Let's take a look: Performance New Latest Intel hardware support - Harnessing the latest in chip-level support for virtualization, VirtualBox 3.2 supports new Intel Core i5 and i7 processor and Intel Xeon processor 5600 Series support for Unrestricted Guest Execution bringing faster boot times for everything from Windows to Solaris guests; New Large Page support - Reducing the size and overhead of key system resources, Large Page support delivers increased performance by enabling faster lookups and shorter table creation times. New In-hypervisor Networking - Significant optimization of the networking subsystem has reduced context switching between guests and host, increasing network throughput by up to 25%. New New Storage I/O subsystem - VirtualBox 3.2 offers a completely re-worked virtual disk subsystem which utilizes asynchronous I/O to achieve high-performance whilst maintaining high data integrity; New Remote Video Acceleration - The unique built-in VirtualBox Remote Display Protocol (VRDP), which is primarily used in virtual desktop infrastructure deployments, has been enhanced to deliver video acceleration. This delivers a rich user experience coupled with reduced computational expense, which is vital when servers are running hundreds of virtual machines; Power New Page Fusion - Traditional Page Sharing techniques have suffered from long and expensive cache construction as pages are scrutinized as candidates for de-duplication. Taking a smarter approach, VirtualBox Page Fusion uses intelligence in the guest virtual machine to determine much more rapidly and accurately those pages which can be eliminated thereby increasing the capacity or vm density of the system; New Memory Ballooning- Ballooning provides another method to increase vm density by allowing the memory of one guest to be recouped and made available to others; New Multiple Virtual Monitors - VirtualBox 3.2 now supports multi-headed virtual machines with up to 8 virtual monitors attached to a guest. Each virtual monitor can be a host window, or be mapped to the hosts physical monitors; New Hot-plug CPU's - Modern operating systems such Windows Server 2008 x64 Data Center Edition or the latest Linux server platforms allow CPUs to be dynamically inserted into a system to provide incremental computing power while the system is running. Version 3.2 introduces support for Hot-plug vCPUs, allowing VirtualBox virtual machines to be given more power, with zero-downtime of the guest; New Virtual SAS Controller - VirtualBox 3.2 now offers a virtual SAS controller, enabling it to run the most demanding of high-end guests; New Online Snapshot Merging - Snapshots are powerful but can eat up disk space and need to be pruned from time to time. Historically, machines have needed to be turned off to delete or merge snapshots but with VirtualBox 3.2 this operation can be done whilst the machines are running. This allows sophisticated system management with minimal interruption of operations; New OVF Enhancements - VirtualBox has supported the OVF standard for virtual machine portability for some time. Now with 3.2, VirtualBox specific configuration data is also stored in the standard allowing richer virtual machine definitions without compromising portability; New Guest Automation - The Guest Automation APIs allow host-based logic to drive operations in the guest; Platforms New USB Keyboard and Mouse - Support more guests that require USB input devices; New Oracle Enterprise Linux 5.5 - Support for the latest version of Oracle's flagship Linux platform; New Ubuntu 10.04 ("Lucid Lynx") - Support for both the desktop and server version of the popular Ubuntu Linux distribution; And as a man once said, "just one more thing" ... New Mac OS X (experimental) - On Apple hardware only, support for creating virtual machines run Mac OS X. All in all this is a pretty powerful release packed full of innovation and speedups. So what are you waiting for?  -FB 

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• Oracle Retail Mobile Point-of-Service

  - by David Dorf

  When most people discuss mobile in retail, they immediately go to shopping applications.  While I agree the consumer side of mobile is huge, I believe its also important to arm store associates with mobile tools.  There are around a dozen major roll-outs of mobile POS to chain retailers, and all have been successful.  This does not, however, signal the demise of traditional registers.  Retailers will adopt mobile POS slowly and reduce the number of fixed registers over time, but there's likely to be a combination of both for the foreseeable future.  Even Apple retains at least one fixed register in every store, you just have to know where to look. The business benefits for mobile POS are pretty straightforward: 1. Faster checkout.  Walmart's CFO recently reported that for every second they shave off the average transaction time, they can potentially save $12M a year in labor.  I think its more likely that labor will be redeployed to enhance the customer experience. 2. Smarter associates.  The sales associates on the floor need the same access to information that consumers have, if not more.  They need ready access to product details, reviews, inventory, etc. to meet consumer expectations.  In a recent study, 40% of consumers said a savvy store associate can impact their final product selection more than a website. 3. Lower costs.  Mobile POS hardware (iPod touch + sled) costs about a fifth of fixed registers, not to mention the reclaimed space that can be used for product displays. But almost all Mobile POS solutions can claim those benefits equally.  Where there's differentiation is on the technical side.  Oracle recently announced availability of the Oracle Retail Mobile Point-of-Service, and it has three big technology advantages in the market: 1. Portable. We used a popular open-source component called PhoneGap that abstracts the app from the underlying OS and hardware so that iOS, Android, and other platforms could be supported.  Further, we used Web technologies such as HTML5 and JavaScript, which are commonly known by many programmers, as opposed to ObjectiveC which is more difficult to find.  The screen can adjust to different form-factors and sizes, just like you see with browsers.  In the future when a new, zippy device gets released, retailers will have the option to move to that device more easily than if they used a native app. 2. Flexible.  Our Mobile POS is free with the Oracle Retail Point-of-Service product.  Retailers can use any combination of fixed and mobile registers, and those ratios can change as required.  Perhaps start with 1 mobile and 4 fixed per store, then transition over time to 4 mobile and 1 fixed without any additional software licenses.  Our scalable solution supports lots of combinations. 3. Consistent.  Because our Mobile POS is fully integrated to our traditional POS, the same business logic is reused.  Third-party Mobile POS solutions often handle pricing, promotions, and tax calculations separately leading to possible inconsistencies within the store.  That won't happen with Oracle's solution. For many retailers, Mobile POS can lower costs, increase customer service, and generally enhance a consumer's in-store experience.  Apple led the way, but lots of other retailers are discovering the many benefits of adding mobile capabilities in their stores.  Just be sure to examine both the business and technology benefits so you get the most value from your solution for the longest period of time.

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• questions about dual-boot install Ubuntu 10.04 and Windows 7 on same hard drive

  - by Tim

  I'd like to dual-boot install Ubuntu 10.04 on the same hard drive as Windows 7 which has already been installed. As to sources on the internet: I found a website iinet about dual-boot installation of Ubuntu 10.10 and Windows 7 on the same hard drive, which I think more specific than the one on Ubuntu Community without specific version of the OSes. Since I am installing Ubuntu 10.04 instead of 10.10, my question is whether their installers are same or almost same and if I can follow iinet for my dual-boot installation? Or are there better websites for information about dual-boot installtion of Ubuntu 10.04 and Windows 7? As to shrinking Windows partitions to make free space for Ubuntu partitions: iinet uses the partition software in Ubuntu's installer to shrink the Windows partition. But I saw in many website that the partition software in Ubuntu's installer cannot guarantee shrinking Windows 7 partitions successfully, so they recommended in general to shrink Windows partitions under Windows itself using its softwares. For example, in Ubuntu Community, it says: Some people think that the Windows partition must be resized only from within Windows Vista and Windows 7 using the shrink/resize option. ... If you use GParted Partition Editor in the Ubuntu Live CD be careful. So I was wondering which way to go in my situation? As to partition for bootloader files: In iinet, I don't see there is a partition created and dedicated to boot files (i.e. Grub files). However, I saw in many websites strongly suggesting using a boot partition for Grub files, especially for the purpose of separation and protection from installed OS files. I was wondering which way I should choose and why? As to installing bootloader Grub, in iinet, I see that to install Grub it only needs to specify the hard drive device for bootloader installation. However, in ubuntuguide(for more than 2 OSes and Ubuntu 9.04), some commands are needed to run in order to put Grub configuration files in MBR, and OS partition, for the chain-load process (where to find the files for the next stage). In Ubuntu Community, there are some related sentences which I don't quite understand how to do in practice: the only thing in your computer outside of Ubuntu that needs to be changed is a small code in the MBR (Master Boot Record) of the first hard disk. The MBR code is changed to point to the boot loader in Ubuntu. If you have a problem with changing the MBR code, you might prefer to just install the code for pointing to GRUB to the first sector of your Ubuntu partition instead. If you do that during the Ubuntu installation process, then Ubuntu won't boot until you configure some other boot manager to point to Ubuntu's boot sector. Windows Vista no longer utilizes boot.ini, ntdetect.com, and ntldr when booting. Instead, Vista stores all data for its new boot manager in a boot folder. Windows Vista ships with an command line utility called bcdedit.exe, which requires administrator credentials to use. You may want to read http://go.microsoft.com/fwlink/?LinkId=112156 about it. Using a command line utility always has its learning curve, so a more productive and better job can be done with a free utility called EasyBCD, developed and mastered in during the times of Vista Beta already. EasyBCD is user friendly and many Vista users highly recommend EasyBCD. In what is quoted above, I was wondering how exactly I should change the MBR code to point to the bootloader in Ubuntu? if I fail to change MBR code, are the other suggested boot managers being bcdedit.exe and EasyBCD in Windows? With the three sources above, which one shall I follow? Thanks and regards

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• Understanding the Customer Form in Release 12 from an AR Perspective!!

  - by user793553

  Confused by the Customer Form in Release 12??  Read on, to get some insight into the evolution of this screen, and how it links in with Trading Community Architecture. Historically, the customer data model was owned by Oracle Receivables (AR).  However, as the data model changed and more complex relationships and attributes had to be tracked and monitored, the Trading Community Architecture (TCA) product was created.  All applications within the E-Business suite that require interaction with a customer integrate with TCA. Customer information is no longer stored in the individual applications but rather in a central repository/registry maintained within TCA.  It is important to understand the following entities/concepts stored in TCA: Party: A party is an entity with whom you can have a potential business relationship.  A party can be either a Person or an Organization.  The Party entity is completely independent of any business relationship; this means that a Party can exist even if you have no transactions with it.   The Party is the "umbrella" entity under which you capture all other attributes listed below. Customer: A customer is a party with whom you have an existing business relationship.  From an AR perspective, you can simplify the concepts by thinking of a Customer as a Party. This definition however does not apply to all other applications. In the Oracle Receivables Customer form, the information displayed at the Customer level is from TCA's Party information record. Customer Account (also called Account): An account contains information about how you transact business with a particular customer.  You can create multiple accounts for a customer.  When you create invoices and receipts you associate it to a particular Account of a Customer. Location: A Location is an address.  It is a point in space, typically identified by a street number, a street name, a city, a state or province, a country.  A location is independent of what it is used for - you do not associate a purpose to a location. Party Site: A Party Site is associated to a Party.  It is the location where a party is physically located.  When defining sites for a Party, only one can be an identifying address.  However, you can define other party sites associated to a party. You can define purposes/usage for Party Sites. Account Site: An Account Site is associated to a Customer Account. It is the location associated to the account you are transacting business with. You can define business purposes (also called site uses) for an Account site. Read more about the Customer Workbench in these notes: Doc ID 1436547.1 Oracle Receivables: Understanding the Customer Form in Release 12 Doc ID  1437866.1 Customer Form - Address: Troubleshooting, Known Issues and Patches Doc ID  1448442.1 Oracle Receivables (AR): Customer Workbench Information Center Do you find this type of blog entry useful?  Please add comments to let us know how we can help you more effectively.  Thank you!

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• Microsoft Build 2012 Day 1 Keynote Summary

  - by Tim Murphy

  So I have finally dried the tears after watching the Keynote for Build 2012.  This wasn’t because it was an emotional presentation, but because for the second year I missed the goodies.  Each on site attendee got a Surface RT, a Lumia 920 and a voucher for 100GB of SkyDrive storage. The event was opened with the announcement that in the three days since the launch of Windows 8 over 4 million upgrades have been sold.  I don’t care who you are that is an impressive stat.  Ballmer then spent a fair amount of time remaking the case for the Windows and Windows Phone platforms similar to what we have heard over the last to launch events. There were some cool, but non-essential demos.  The one that was the most fun was the Perceptive Pixel 82” slate device.  At first glance I wondered why I would ever want such a device, but then Ballmer explained it’s possible use for schools and boardrooms.  The actually made sense. Then things got strange.  Steve started explaining features that developers could leverage.  Usually this type of information is left to the product leads.  He focused on the integration with the Charms features such as Search and Share. Steve “Guggs” Guggenheim showed off an app that would appeal to my kids from Disney called “Agent P” which is base on Phineas and Ferb.  Then he got to the meat of the presentation.  We found out that you could add a tile that can be used to sell ad space.  In the same vein we also found out that you could use Microsoft’s, Paypal’s or any commerce engine of your own creation or choosing. For those who are interested in sports and especially developing sports apps you would have found the small presentation from Michael Bayle of ESPN.  He introduced the ESPN app which has tons of features.  For the developers in the crowd he also mentioned that ESPN has an API available at developer.espn.com. During the launch events we were told apps were coming.  In this presentation we were actually shown a scrolling list of logos and told about a couple of them.  Ballmer mentioned specifically Twitter, SAP and DropBox.  These are impressive names that were just a couple of the list impressive names. Steve Ballmer addressed the question of why you should develop for the Windows 8 platform.  He feels that Microsoft has the best commercial terms for developers, a better way to build apps than other platforms and a variety of form factors.  His key point though was the available volume of customers given the current Windows install base and assuming even a flat growth of the platform.  This he backed with a promise that Microsoft is going to do better at marketing and you won’t be able to avoid the ads that they are bringing out. The last section of the key note was present by Kevin Gallo from the Windows Phone team.  This was the real reason I tuned into the webcast.  He impressed upon those watching that the strength of developing for the Microsoft platform is the common programming model that now exist.  While there are difference between form factor implementations you can leverage code across them. He claimed that 90% of developer requests for Windows Phone 8 had been implemented.  These include: More controls with better performance Better live tiles including lock screen integration Speech support in custom apps Easier submission to the market place App camera integration VOIP and chat support Bluetooth and NFC support Native C++ development Direct 3D development   The quote from Kevin that stood out for me was that “Take your Dramamine and buckle your seatbelt type of games are coming to Windows Phone 8”.  He back this up by displaying a list of game development frameworks and then having Unity come out and do a demo. Ok, almost done … The last two things of note for me were the announcement that the SDK is immediately available at dev.windowsphone.com and that they were reducing the cost of an individual developer account to $8 for the next 8 days. Let the development commence. del.icio.us Tags: Build 2012,Windows 8,Windows Phone 8,Windows Phone

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• apt-get upgrade stuck at the same package

  - by decibyte

  Current status I've started to suspect this is not an Ubuntu issue, but related to the internet connection here at my work. Until I'm sure, Im leaving my question below: Original question I'm stuck, can't upgrade my system. Running sudo apt-get upgrade gives me the following: mmm@alalunga:~$ sudo apt-get upgrade Reading package lists... Done Building dependency tree Reading state information... Done The following packages have been kept back: ginn libgrip0 linux-generic-pae linux-headers-generic-pae linux-image-generic-pae The following packages will be upgraded: apport apport-gtk bind9-host build-essential dhcp3-client dhcp3-common dnsutils eog evince evince-common firefox firefox-branding firefox-dbg firefox-globalmenu firefox-gnome-support firefox-locale-en gimp gimp-data gir1.2-totem-1.0 glib-networking glib-networking-common glib-networking-services gnupg gpgv icedtea-6-jre-cacao icedtea-6-jre-jamvm icedtea-6-plugin icedtea-netx icedtea-netx-common icedtea-plugin isc-dhcp-client isc-dhcp-common libapache2-mod-php5 libart-2.0-2 libbind9-80 libdns81 libevince3-3 libgimp2.0 libisc83 libisccc80 libisccfg82 liblwres80 libssl-dev libssl-doc libssl1.0.0 libtotem0 linux-firmware linux-libc-dev openjdk-6-jre openjdk-6-jre-headless openjdk-6-jre-lib openssl php-pear php5-cli php5-common php5-curl php5-dev php5-gd php5-mysql php5-xsl policykit-1-gnome python-apport python-django python-gst0.10 python-problem-report resolvconf thunderbird thunderbird-globalmenu thunderbird-gnome-support totem totem-common totem-mozilla totem-plugins xserver-xorg-input-synaptics 74 upgraded, 0 newly installed, 0 to remove and 5 not upgraded. Need to get 317 MB/327 MB of archives. After this operation, 1.481 kB of additional disk space will be used. Do you want to continue [Y/n]? Get:1 http://archive.ubuntu.com/ubuntu/ precise-updates/main openjdk-6-jre-headless i386 6b24-1.11.4-1ubuntu0.12.04.1 [27,3 MB] Get:2 http://archive.ubuntu.com/ubuntu/ precise-updates/main openjdk-6-jre-headless i386 6b24-1.11.4-1ubuntu0.12.04.1 [27,3 MB] Get:3 http://archive.ubuntu.com/ubuntu/ precise-updates/main openjdk-6-jre-headless i386 6b24-1.11.4-1ubuntu0.12.04.1 [27,3 MB] Get:4 http://archive.ubuntu.com/ubuntu/ precise-updates/main openjdk-6-jre-headless i386 6b24-1.11.4-1ubuntu0.12.04.1 [27,3 MB] Get:5 http://archive.ubuntu.com/ubuntu/ precise-updates/main openjdk-6-jre-headless i386 6b24-1.11.4-1ubuntu0.12.04.1 [27,3 MB] Get:6 http://archive.ubuntu.com/ubuntu/ precise-updates/main openjdk-6-jre-headless i386 6b24-1.11.4-1ubuntu0.12.04.1 [27,3 MB] Get:7 http://archive.ubuntu.com/ubuntu/ precise-updates/main openjdk-6-jre-headless i386 6b24-1.11.4-1ubuntu0.12.04.1 [27,3 MB] 9% [7 openjdk-6-jre-headless 27,3 MB/27,3 MB 100%] It keeps downloading the package openjdk-6-jre-headless, then does nothing for a while (hanging on what's the last line above), then download the package again. It's at its 13th download attempt at the moment of writing. The actual downloads seem to be done just fine, but whatever it does after downloading seems to be failing. I tried removing openjdk-6, but then it wanted to install openjdk-7 instead, with the same result, hanging at openjdk-7-jre-headless instead. I also tried changing servers from my local (Danish) to the main server. No luck. It's also keeping me from upgrading alle the other packages. What to do? Update After following instructions in the answer by @lpanebr, it is now stuck at the linux-firmware package. So, maybe it's a more general problem than being related to specific package(s)? Although it did download some packages without problems before getting stuck at linux-firmware.

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• Viewport / Camera Calculation in 2D Game

  - by Dave

  we have a 2D game with some sprites and tiles and some kind of camera/viewport, that "moves" around the scene. so far so good, if we wouldn't had some special behaviour for your camera/viewport translation. normally you could stick the camera to your player figure and center it, resulting in a very cheap, undergraduate, translation equation, like : vec_translation -/+= speed (depending in what keys are pressed. WASD as default.) buuuuuuuuuut, we want our player figure be able to actually reach the bounds, when the viewport/camera has reached a maximum translation. we came up with the following solution (only keys a and d are the shown here, the rest is just adaption of calculation or maybe YOUR super-cool and elegant solution :) ): if(keys[A]) { playerX -= speed; if(playerScreenX <= width / 2 && tx < 0) { playerScreenX = width / 2; tx += speed; } else if(playerScreenX <= width / 2 && (tx) >= 0) { playerScreenX -= speed; tx = 0; if(playerScreenX < 0) playerScreenX = 0; } else if(playerScreenX >= width / 2 && (tx) < 0) { playerScreenX -= speed; } } if(keys[D]) { playerX += speed; if(playerScreenX >= width / 2 && (-tx + width) < sceneWidth) { playerScreenX = width / 2; tx -= speed; } if(playerScreenX >= width / 2 && (-tx + width) >= sceneWidth) { playerScreenX += speed; tx = -(sceneWidth - width); if(playerScreenX >= width - player.width) playerScreenX = width - player.width; } if(playerScreenX <= width / 2 && (-tx + width) < sceneWidth) { playerScreenX += speed; } } i think the code is rather self explaining: keys is a flag container for currently active keys, playerX/-Y is the position of the player according to world origin, tx/ty are the translation components vital to background / npc / item offset calculation, playerOnScreenX/-Y is the actual position of the player figure (sprite) on screen and width/height are the dimensions of the camera/viewport. this all looks quite nice and works well, but there is a very small and nasty calculation error, which in turn sums up to some visible effect. let's consider following piece of code: if(playerScreenX <= width / 2 && tx < 0) { playerScreenX = width / 2; tx += speed; } it can be translated into plain english as : if the x position of your player figure on screen is less or equal the half of your display / camera / viewport size AND there is enough space left LEFT of your viewport/camera then set players x position on screen to width half, increase translation (because we subtract the translation from something we want to move). easy, right?! doing this will create a small delta between playerX and playerScreenX. after so much talking, my question appears now here at the bottom of this document: how do I stick the calculation of my player-on-screen to the actual position of the player AND having a viewport that is not always centered aroung the players figure? here is a small test-case in processing: http://pastebin.com/bFaTauaa thank you for reading until now and thank you in advance for probably answering my question.

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• Reducing Deadlocks - not a DBA issue ?

  - by steveh99999

   As a DBA, I'm involved on an almost daily basis troubleshooting 'SQL Server' performance issues. Often, this troubleshooting soon veers away from a 'its a SQL Server issue' to instead become a wider application/database design/coding issue.One common perception with SQL Server is that deadlocking is an application design issue - and is fixed by recoding...  I see this reinforced by MCP-type questions/scenarios where the answer to prevent deadlocking is simply to change the order in code in which tables are accessed....Whilst this is correct, I do think this has led to a situation where many 'operational' or 'production support' DBAs, when faced with a deadlock, are happy to throw the issue over to developers without analysing the issue further....A couple of 'war stories' on deadlocks which I think are interesting :- Case One , I had an issue recently on a third-party application that I support on SQL 2008.  This particular third-party application has an unusual support agreement where the customer is allowed to change the index design on the third-party provided database.  However, we are not allowed to alter application code or modify table structure..This third-party application is also known to encounter occasional deadlocks – indeed, I have documentation from the vendor that up to 50 deadlocks per day is not unusual !So, as a DBA I have to support an application which in my opinion has too many deadlocks - but, I cannot influence the design of the tables or stored procedures for the application. This should be the classic - blame the third-party developers scenario, and hope this issue gets addressed in a future application release - ie we could wait years for this to be resolved and implemented in our production environment...But, as DBAs  can change the index layout, is there anything I could do still to reduce the deadlocks in the application ?I initially used SQL traceflag 1222 to write deadlock detection output to the SQL Errorlog – using this I was able to identify one table heavily involved in the deadlocks.When I examined the table definition, I was surprised to see it was a heap – ie no clustered index existed on the table.Using SQL profiler to see locking behaviour and plan for the query involved in the deadlock, I was able to confirm a table scan was being performed.By creating an appropriate clustered index - it was possible to produce a more efficient plan and locking behaviour.So, less locks, held for less time = less possibility of deadlocks. I'm still unhappy about the overall number of deadlocks on this system - but that's something to be discussed further with the vendor.Case Two,  a system which hadn't changed for months suddenly started seeing deadlocks on a regular basis. I love the 'nothing's changed' scenario, as it gives me the opportunity to appear wise and say 'nothings changed on this system, except the data'.. This particular deadlock occurred on a table which had been growing rapidly. By using DBCC SHOW_STATISTICS - the DBA team were able to see that the deadlocks seemed to be occurring shortly after auto-update stats had regenerated the table statistics using it's default sampling behaviour.As a quick fix, we were able to schedule a nightly UPDATE STATISTICS WITH FULLSCAN on the table involved in the deadlock - thus, greatly reducing the potential for stats to be updated via auto_update_stats, consequently reducing the potential for a bad plan to be generated based on an unrepresentative sample of the data. This reduced the possibility of a deadlock occurring.  Not a perfect solution by any means, but quick, easy to implement, and needed no application code changes. This fix gave us some 'breathing space'  to properly fix the code during the next scheduled application release.   The moral of this post - don't dismiss deadlocks as issues that can only be fixed by developers...

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• .NET Code Evolution

  - by Alois Kraus

  Originally posted on: http://geekswithblogs.net/akraus1/archive/2013/07/24/153504.aspxAt my day job I do look at a lot of code written by other people. Most of the code is quite good and some is even a masterpiece. And there is also code which makes you think WTF… oh it was written by me. Hm not so bad after all. There are many excuses reasons for bad code. Most often it is time pressure followed by not enough ambition (who cares) or insufficient training. Normally I do care about code quality quite a lot which makes me a (perceived) slow worker who does write many tests and refines the code quite a lot because of the design deficiencies. Most of the deficiencies I do find by putting my design under stress while checking for invariants. It does also help a lot to step into the code with a debugger (sometimes also Windbg). I do this much more often when my tests are red. That way I do get a much better understanding what my code really does and not what I think it should be doing. This time I do want to show you how code can evolve over the years with different .NET Framework versions. Once there was  time where .NET 1.1 was new and many C++ programmers did switch over to get rid of not initialized pointers and memory leaks. There were also nice new data structures available such as the Hashtable which is fast lookup table with O(1) time complexity. All was good and much code was written since then. At 2005 a new version of the .NET Framework did arrive which did bring many new things like generics and new data structures. The “old” fashioned way of Hashtable were coming to an end and everyone used the new Dictionary<xx,xx> type instead which was type safe and faster because the object to type conversion (aka boxing) was no longer necessary. I think 95% of all Hashtables and dictionaries use string as key. Often it is convenient to ignore casing to make it easy to look up values which the user did enter. An often followed route is to convert the string to upper case before putting it into the Hashtable. Hashtable Table = new Hashtable(); void Add(string key, string value) { Table.Add(key.ToUpper(), value); } This is valid and working code but it has problems. First we can pass to the Hashtable a custom IEqualityComparer to do the string matching case insensitive. Second we can switch over to the now also old Dictionary type to become a little faster and we can keep the the original keys (not upper cased) in the dictionary. Dictionary<string, string> DictTable = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase); void AddDict(string key, string value) { DictTable.Add(key, value); } Many people do not user the other ctors of Dictionary because they do shy away from the overhead of writing their own comparer. They do not know that .NET has for strings already predefined comparers at hand which you can directly use. Today in the many core area we do use threads all over the place. Sometimes things break in subtle ways but most of the time it is sufficient to place a lock around the offender. Threading has become so mainstream that it may sound weird that in the year 2000 some guy got a huge incentive for the idea to reduce the time to process calibration data from 12 hours to 6 hours by using two threads on a dual core machine. Threading does make it easy to become faster at the expense of correctness. Correct and scalable multithreading can be arbitrarily hard to achieve depending on the problem you are trying to solve. Lets suppose we want to process millions of items with two threads and count the processed items processed by all threads. A typical beginners code might look like this: int Counter; void IJustLearnedToUseThreads() { var t1 = new Thread(ThreadWorkMethod); t1.Start(); var t2 = new Thread(ThreadWorkMethod); t2.Start(); t1.Join(); t2.Join(); if (Counter != 2 * Increments) throw new Exception("Hmm " + Counter + " != " + 2 * Increments); } const int Increments = 10 * 1000 * 1000; void ThreadWorkMethod() { for (int i = 0; i < Increments; i++) { Counter++; } } It does throw an exception with the message e.g. “Hmm 10.222.287 != 20.000.000” and does never finish. The code does fail because the assumption that Counter++ is an atomic operation is wrong. The ++ operator is just a shortcut for Counter = Counter + 1 This does involve reading the counter from a memory location into the CPU, incrementing value on the CPU and writing the new value back to the memory location. When we do look at the generated assembly code we will see only inc dword ptr [ecx+10h] which is only one instruction. Yes it is one instruction but it is not atomic. All modern CPUs have several layers of caches (L1,L2,L3) which try to hide the fact how slow actual main memory accesses are. Since cache is just another word for redundant copy it can happen that one CPU does read a value from main memory into the cache, modifies it and write it back to the main memory. The problem is that at least the L1 cache is not shared between CPUs so it can happen that one CPU does make changes to values which did change in meantime in the main memory. From the exception you can see we did increment the value 20 million times but half of the changes were lost because we did overwrite the already changed value from the other thread. This is a very common case and people do learn to protect their  data with proper locking.   void Intermediate() { var time = Stopwatch.StartNew(); Action acc = ThreadWorkMethod_Intermediate; var ar1 = acc.BeginInvoke(null, null); var ar2 = acc.BeginInvoke(null, null); ar1.AsyncWaitHandle.WaitOne(); ar2.AsyncWaitHandle.WaitOne(); if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Intermediate did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Intermediate() { for (int i = 0; i < Increments; i++) { lock (this) { Counter++; } } } This is better and does use the .NET Threadpool to get rid of manual thread management. It does give the expected result but it can result in deadlocks because you do lock on this. This is in general a bad idea since it can lead to deadlocks when other threads use your class instance as lock object. It is therefore recommended to create a private object as lock object to ensure that nobody else can lock your lock object. When you read more about threading you will read about lock free algorithms. They are nice and can improve performance quite a lot but you need to pay close attention to the CLR memory model. It does make quite weak guarantees in general but it can still work because your CPU architecture does give you more invariants than the CLR memory model. For a simple counter there is an easy lock free alternative present with the Interlocked class in .NET. As a general rule you should not try to write lock free algos since most likely you will fail to get it right on all CPU architectures. void Experienced() { var time = Stopwatch.StartNew(); Task t1 = Task.Factory.StartNew(ThreadWorkMethod_Experienced); Task t2 = Task.Factory.StartNew(ThreadWorkMethod_Experienced); t1.Wait(); t2.Wait(); if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Experienced did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Experienced() { for (int i = 0; i < Increments; i++) { Interlocked.Increment(ref Counter); } } Since time does move forward we do not use threads explicitly anymore but the much nicer Task abstraction which was introduced with .NET 4 at 2010. It is educational to look at the generated assembly code. The Interlocked.Increment method must be called which does wondrous things right? Lets see: lock inc dword ptr [eax] The first thing to note that there is no method call at all. Why? Because the JIT compiler does know very well about CPU intrinsic functions. Atomic operations which do lock the memory bus to prevent other processors to read stale values are such things. Second: This is the same increment call prefixed with a lock instruction. The only reason for the existence of the Interlocked class is that the JIT compiler can compile it to the matching CPU intrinsic functions which can not only increment by one but can also do an add, exchange and a combined compare and exchange operation. But be warned that the correct usage of its methods can be tricky. If you try to be clever and look a the generated IL code and try to reason about its efficiency you will fail. Only the generated machine code counts. Is this the best code we can write? Perhaps. It is nice and clean. But can we make it any faster? Lets see how good we are doing currently. Level Time in s IJustLearnedToUseThreads Flawed Code Intermediate 1,5 (lock) Experienced 0,3 (Interlocked.Increment) Master 0,1 (1,0 for int[2]) That lock free thing is really a nice thing. But if you read more about CPU cache, cache coherency, false sharing you can do even better. int[] Counters = new int[12]; // Cache line size is 64 bytes on my machine with an 8 way associative cache try for yourself e.g. 64 on more modern CPUs void Master() { var time = Stopwatch.StartNew(); Task t1 = Task.Factory.StartNew(ThreadWorkMethod_Master, 0); Task t2 = Task.Factory.StartNew(ThreadWorkMethod_Master, Counters.Length - 1); t1.Wait(); t2.Wait(); Counter = Counters[0] + Counters[Counters.Length - 1]; if (Counter != 2 * Increments) throw new Exception(String.Format("Hmm {0:N0} != {1:N0}", Counter, 2 * Increments)); Console.WriteLine("Master did take: {0:F1}s", time.Elapsed.TotalSeconds); } void ThreadWorkMethod_Master(object number) { int index = (int) number; for (int i = 0; i < Increments; i++) { Counters[index]++; } } The key insight here is to use for each core its own value. But if you simply use simply an integer array of two items, one for each core and add the items at the end you will be much slower than the lock free version (factor 3). Each CPU core has its own cache line size which is something in the range of 16-256 bytes. When you do access a value from one location the CPU does not only fetch one value from main memory but a complete cache line (e.g. 16 bytes). This means that you do not pay for the next 15 bytes when you access them. This can lead to dramatic performance improvements and non obvious code which is faster although it does have many more memory reads than another algorithm. So what have we done here? We have started with correct code but it was lacking knowledge how to use the .NET Base Class Libraries optimally. Then we did try to get fancy and used threads for the first time and failed. Our next try was better but it still had non obvious issues (lock object exposed to the outside). Knowledge has increased further and we have found a lock free version of our counter which is a nice and clean way which is a perfectly valid solution. The last example is only here to show you how you can get most out of threading by paying close attention to your used data structures and CPU cache coherency. Although we are working in a virtual execution environment in a high level language with automatic memory management it does pay off to know the details down to the assembly level. Only if you continue to learn and to dig deeper you can come up with solutions no one else was even considering. I have studied particle physics which does help at the digging deeper part. Have you ever tried to solve Quantum Chromodynamics equations? Compared to that the rest must be easy ;-). Although I am no longer working in the Science field I take pride in discovering non obvious things. This can be a very hard to find bug or a new way to restructure data to make something 10 times faster. Now I need to get some sleep ….

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• How to get faster graphics in KVM? VNC is painfully slow with Haiku OS guest, Spice won't install and SDL doesn't work

  - by Don Quixote

  I've been coming up to speed on the Haiku operating system, an Open Source clone of BeOS 5 Pro. I'm using an Apple MacBook Pro as my development machine. Apple's BootCamp BIOS does not support more than four partitions on the internal hard drive. While I can set up extended and logical partitions, doing so will prevent any of the installed operating systems from booting. To run Haiku directly on the iron, I boot it off a USB stick. Using external storage is also helpful because I am perpetually out of filesystem space. While VirtualBox is documented to allow access to physical drives, I could not actually get it to work. Also VirtualBox can only use one of the host CPU's cores. While VB guests can be configured for more than one CPU, they are only emulated. A full build of the Haiku OS takes 4.5 under VB. I had the hope of reducing build times by using KVM instead, but it's not working nearly as well as VirtualBox did. The Linux Kernel Virtual Machine is broken in all manner of fundamental ways as seen from Haiku. But I'm a coder; maybe I could contribute to fixing some of those problems. The first problem I've got is that Haiku's video in virt-manager is quite painfully slow. When I drag Haiku windows around the desktop, they lag quite far behind where my mouse is. It's quite difficult to move a window to a precise position on the screen. Just imagine that the mouse was connected to the window title bar with a really stretchy spring. Also Haiku's mouse lags quite far behind where I have moved it. I found lots of Personal Package Archives that enable Spice from QEMU / KVM at the Ubuntu Personal Package Arhives. I tried a few of the PPAs but none of them worked; with one of them, the command "add-apt-repository" crashed with a traceback. There is a Wiki page about Spice, but it says that it only works on 64-bit. My Early 2006 MacBook Pro is 32-bit. Its Apple Model Identifier is MacBookPro1,1; these use Core Duos NOT Core 2 Duos. I don't mind building a source deb for 32-bit if I can expect it to work. Is there some reason that Spice should be 64-bit only? Does it need features of the x86_64 Instruction Set Architecture that x86 does not have? When I try using SDL from virt-manager, the configuration for Local SDL Window says "Xauth: /home/mike/.Xauthority". When I try to start my guest, virt-manager emits an error. When I Googled the error message, the usual solution was to make ~/.Xauthority readible. However, .Xauthorty does not exist in my home directory. Instead I have a $XAUTHORITY environment variable. There is no way to configure SDL in virt-manager to use $XAUTHORITY instead of ~/.Xauthority. Neither does it work to copy the value of $XAUTHORITY into the file. I am ready to scream, because I've been five fscking days trying to make KVM work for Haiku development. There is a whole lot more that is broken than the slow video. All I really want to do for now is speed up my full builds of Haiku by using "jam -j2" to use both cores in my CPU. I may try Xen next, but the last time I monkeyed with Xen it was far, far more broken than I am finding KVM to be. Just for now, I would be satisfied if there were some way to use my USB stick as a drive in VirtualBox. VB does allow me to configure /dev/sdb as a drive, but it always causes a fatal error when I try to launch the guest. Thank You For Any Advice You Can Give Me. -

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• Additional new material WebLogic Community

  - by JuergenKress

  Virtual Developer Conference On Demand - Register Updated Book: WebLogic 12c: Distinctive Recipes - Architecture, Development, Administration by Oracle ACE Director Frank Munz - Blog | YouTube Webcast: Migrating from GlassFish to WebLogic - Replay Reliance Commercial Finance Accelerates Time-to-Market, Improves IT Staff Productivity by 70% - Blog | Oracle Magazine Retrieving WebLogic Server Name and Port in ADF Application by Andrejus Baranovskis, Oracle Ace Director - Blog Using Oracle WebLogic 12c with NetBeans IDEOracle ACE Director Markus Eisele walks you through installing and configuring all the necessary components, and helps you get started with a simple Hello World project. Read the article. Video: Oracle A-Team ADF Mobile Persistence SampleThis video by Oracle Fusion Middleware A-Team architect Steven Davelaar demonstrates how to use the ADF Mobile Persistence Sample JDeveloper extension to generate a fully functional ADF Mobile application that reads and writes data using an ADF BC SOAP web service. Watch the video. Java ME 8 ReleaseDownload Java ME today! This release is an implementation of the Java ME 8 standards JSR 360 (CLDC 8) and JSR 361 (MEEP 8), and includes support of alignment with Java SE 8 language features and APIs, an enhanced services-enabled application platform, the ability to "right-size" the platform to address a wide range of target devices, and more. Learn more Download Java ME SDK 8It includes application development support for Oracle Java ME Embedded 8 platforms and includes plugins for NetBeans 8. See the Java ME 8 Developer Tools Documentation to learn JavaOne 2014 Early Bird RateRegister early to save $400 off the onsite price. With the release of Java 8 this year, we have exciting new sessions and an interactive demo space! NetBeans IDE 8.0 Patch UpdateThe NetBeans Team has released a patch for NetBeans IDE 8.0. Download it today to get fixes that enhance stability and performance. Java 8 Questions ForumFor any questions about this new release, please join the conversation on the Java 8 Questions Forum. Java ME 8: Getting Started with Samples and Demo CodeLearn in few steps how to get started with Java ME 8! The New Java SE 8 FeaturesJava SE 8 introduces enhancements such as lambda expressions that enable you to write more concise yet readable code, better utilize multicore systems, and detect more errors at compile time. See What's New in JDK 8 and the new Java SE 8 documentation portal. Pay Less for Java-Related Books!Save 20% on all new Oracle Press books related to Java. Download the free preview sampler for the Java 8 book written by Herbert Schildt, Maurice Naftain, Henrik Ebbers and J.F. DiMarzio. New book: EJB 3 in Action, Second Edition WebLogic 12c Does WebSockets Getting Started by C2B2 Video: Building Robots with Java Embedded Video: Nighthacking TV Watch presentations by Stephen Chin and community members about Java SE, Java Embedded, Java EE, Hadoop, Robots and more. Migrating the Spring Pet Clinic to Java EE 7 Trip report : Jozi JUG Java Day in Johannesburg How to Build GlassFish 4 from Source 4,000 posts later : The Aquarium WebLogic Partner Community For regular information become a member in the WebLogic Partner Community please visit: http://www.oracle.com/partners/goto/wls-emea ( OPN account required). If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Mix Forum Wiki Technorati Tags: WebLogic,WebLogic Community,Oracle,OPN,Jürgen Kress

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• JavaOne User Group Sunday

  - by Tori Wieldt

  Before any "official" sessions of JavaOne 2012, the Java community was already sizzling. User Group Sunday was a great success, with several sessions offered by Java community members for anyone wanting to attend. Sessions were both about Java and best practices for running a JUG. Technical sessions included "Autoscaling Web Java Applications: Handle Peak Traffic with Zero Downtime and Minimized Cost,"  "Using Java with HTML5 and CSS3," and "Gooey and Sticky Bits: Everything You Ever Wanted to Know About Java." Several sessions were about how to start and run a JUG, like "Getting Speakers, Finding Sponsors, Planning Events: A Day in the Life of a JUG" and "JCP and OpenJDK: Using the JUGs’ “Adopt” Programs in Your Group." Badr ElHouari and Faiçal Boutaounte presented the session "Why Communities Are Important and How to Start One." They used the example of the Morocco JUG, which they started. Before the JUG, there was no "Java community," they explained. They shared their best practices, including: have fun, enjoy what you are doing get a free venue to have regular meetings, a University is a good choice run a conference, it gives you visibility and brings in new members students are a great way to grow a JUG Badr was proud to mention JMaghreb, a first-time conference that the Morocco JUG is hosting in November. They have secured sponsors and international speakers, and are able to offer a free conference for Java developers in North Africa. The session also included a free-flowing discussion about recruiters (OK to come to meetings, but not to dominate them), giving out email addresses (NEVER do without permission), no-show rates (50% for free events) and the importance of good content (good speakers really help!). Trisha Gee, member of the London Java Community (LJC) was one of the presenters for the session "Benefits of Open Source." She explained how open sourcing the LMAX Disruptor (a high performance inter-thread messaging library) gave her company LMAX several benefits, including more users, more really good quality new hires, and more access to 3rd party companies. Being open source raised the visibility of the company and the product, which was good in many ways. "We hired six really good coders in three months," Gee said. They also got community contributors for their code and more cred with technologists. "We had been unsuccessful at getting access to executives from other companies in the high-performance space. But once we were open source, the techies at the company had heard of us, knew our code was good, and that opened lots of doors for us." So, instead of "giving away the secret sauce," by going open source, LMAX gained many benefits. "It was a great day," said Bruno Souza, AKA The Brazilian Java Man, "the sessions were well attended and there was lots of good interaction." Sizzle and steak!

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• Fun with Python

  - by dotneteer

  I am taking a class on Coursera recently. My formal education is in physics. Although I have been working as a developer for over 18 years and have learnt a lot of programming on the job, I still would like to gain some systematic knowledge in computer science. Coursera courses taught by Standard professors provided me a wonderful chance. The three languages recommended for assignments are Java, C and Python. I am fluent in Java and have done some projects using C++/MFC/ATL in the past, but I would like to try something different this time. I first started with pure C. Soon I discover that I have to write a lot of code outside the question that I try to solve because the very limited C standard library. For example, to read a list of values from a file, I have to read characters by characters until I hit a delimiter. If I need a list that can grow, I have to create a data structure myself, something that I have taking for granted in .Net or Java. Out of frustration, I switched to Python. I was pleasantly surprised to find that Python is very easy to learn. The tutorial on the official Python site has the exactly the right pace for me, someone with experience in another programming. After a couple of hours on the tutorial and a few more minutes of toying with IDEL, I was in business. I like the “battery supplied” philosophy that gives everything that I need out of box. For someone from C# or Java background, curly braces are replaced by colon(:) and tab spaces. Although I tend to miss colon from time to time, I found that the idea of tab space is actually very nice once I get use to them. I also like to feature of multiple assignment and multiple return parameters. When I need to return a by-product, I just add it to the list of returns. When would use Python? I would use Python if I need to computer anything quick. The language is very easy to use. Python has a good collection of libraries (packages). The REPL of the interpreter allows me test ideas quickly before committing them into script. Lots of computer science work have been ported from Lisp to Python. Some universities are even teaching SICP in Python. When wouldn’t I use Python? I mostly would not use it in a managed environment, such as Ironpython or Jython. Both .Net and Java already have a rich library so one has to make a choice which library to use. If we use the managed runtime library, the code will tie to the particular runtime and thus not portable. If we use the Python library, then we will face the relatively long start-up time. For this reason, I would not recommend to use Ironpython for WP7 development. The only situation that I see merit with managed Python is in a server application where I can preload Python so that the start-up time is not a concern. Using Python as a managed glue language is an over-kill most of the time. A managed Scheme could be a better glue language as it is small enough to start-up very fast.

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• Oracle ties social, CRM, analytics products to customer experience

  - by Richard Lefebvre

  Oracle will embark on a new product strategy that centers on customer experience management, an approach driven by the company’s many recent acquisitions.  The new approach, announced by the company Monday night, will be seen in an expansive suite that features familiar Oracle products -- such as its Fusion CRM platform -- and offerings the company recently gained through acquisitions, including FatWire, RightNow and Vitrue. Billed as Oracle Customer Experience (CX), the suite enables businesses to respond to a market centered on the customer experience, said Anthony Lye, the company’s senior vice president of CRM. Companies “are very aware their products are commoditizing,” Lye said in an interview last week, referring to how the Web and social media channels have empowered customers. Customer experiences start and mature outside of CRM, and applications today need to reflect that shift, Lye said. Businesses thus need to step away from a pure CRM model, he said. Oracle claims CX will improve customer experience management by connecting businesses with customers across Web sites and social channels. Companies can create a single, real-time view of the customer and use predictive analytics of interactions to strengthen the customer experience, Oracle said. “Companies have to connect with their customers wherever, whenever and however they want,” Lye said. “They have to know and understand their customer.” Lye promoted Oracle CX as a suite that will work across channels to complement the company’s applications. A new strategy has been “cooking” for years now, but the acquisitions Oracle has made over the past two years made the time right for a “unique collaboration,” Lye said. CX includes basic Oracle CRM solutions such as Siebel and the new Fusion Apps. It also includes the company’s MDM products, Enterprise Data Quality, Customer Hub and Product Hub. And the suite is rounded out by the services that Oracle recently bought, transactions that created or enhanced the company’s presence in social, marketing, e-commerce and customer service. For instance, FatWire provides tools for marketing. ATG focuses on e-commerce. And RightNow specializes in customer service. Two recent acquisitions -- Collective Intellect and Vitrue -- gave Oracle a seat at the social table. Collective Intellect is a social intelligence program, and Vitrue is a social marketing and engagement platform. Those acquisitions have yet to be finalized. Oracle hopes to eventually integrate the two social offerings, as well as most of the other services, into the CX suite. CX can integrate on Oracle’s standard middleware, and can give users a lower TCO by leveraging it as a single stack on premise or as a cloud solution. Lye deferred questions about the pricing of CX, and instead pitched Oracle’s ability to offer multiple customer experience solutions in one suite. Businesses have struggled with the complexity of infrastructure and modern services that communicate with customers, Lye said. “They’ve struggled to pull all these things together. We’ve done that,” he said. Stephen Powers, a research director at Forrester Research Inc. in Cambridge, Mass., said it’s not surprising for Oracle to offer the CX suite and a related customer experience strategy.  “They’ve got CRM, ATG, FatWire. Clearly, it’s been the strategy for them,” he said. But the challenge for Oracle, and for any other vendor that has gone on an “acquisition spree,” is to connect its many products, Powers said. “The portfolio has to be more than the parts. They’ve got to realize the efficiencies and value of having these pieces to tie them together,” he said. “The proof is in the pudding. Adobe has done a nice job in its space with the products they’ve got. Now, Oracle has got to show it has something.” Albert McKeon (SearchCRM) Published: 25 Jun 2012 : http://searchcrm.techtarget.com/news/2240158644/Oracle-ties-social-CRM-analytics-products-to-customer-experience

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• How to convert pitch and yaw to x, y, z rotations?

  - by Aaron Anodide

  I'm a beginner using XNA to try and make a 3D Asteroids game. I'm really close to having my space ship drive around as if it had thrusters for pitch and yaw. The problem is I can't quite figure out how to translate the rotations, for instance, when I pitch forward 45 degrees and then start to turn - in this case there should be rotation being applied to all three directions to get the "diagonal yaw" - right? I thought I had it right with the calculations below, but they cause a partly pitched forward ship to wobble instead of turn.... :( So my quesiton is: how do you calculate the X, Y, and Z rotations for an object in terms of pitch and yaw? Here's current (almost working) calculations for the Rotation acceleration: float accel = .75f; // Thrust +Y / Forward if (currentKeyboardState.IsKeyDown(Keys.I)) { this.ship.AccelerationY += (float)Math.Cos(this.ship.RotationZ) * accel; this.ship.AccelerationX += (float)Math.Sin(this.ship.RotationZ) * -accel; this.ship.AccelerationZ += (float)Math.Sin(this.ship.RotationX) * accel; } // Rotation +Z / Yaw if (currentKeyboardState.IsKeyDown(Keys.J)) { this.ship.RotationAccelerationZ += (float)Math.Cos(this.ship.RotationX) * accel; this.ship.RotationAccelerationY += (float)Math.Sin(this.ship.RotationX) * accel; this.ship.RotationAccelerationX += (float)Math.Sin(this.ship.RotationY) * accel; } // Rotation -Z / Yaw if (currentKeyboardState.IsKeyDown(Keys.K)) { this.ship.RotationAccelerationZ += (float)Math.Cos(this.ship.RotationX) * -accel; this.ship.RotationAccelerationY += (float)Math.Sin(this.ship.RotationX) * -accel; this.ship.RotationAccelerationX += (float)Math.Sin(this.ship.RotationY) * -accel; } // Rotation +X / Pitch if (currentKeyboardState.IsKeyDown(Keys.F)) { this.ship.RotationAccelerationX += accel; } // Rotation -X / Pitch if (currentKeyboardState.IsKeyDown(Keys.D)) { this.ship.RotationAccelerationX -= accel; } I'm combining that with drawing code that does a rotation to the model: public void Draw(Matrix world, Matrix view, Matrix projection, TimeSpan elsapsedTime) { float seconds = (float)elsapsedTime.TotalSeconds; // update velocity based on acceleration this.VelocityX += this.AccelerationX * seconds; this.VelocityY += this.AccelerationY * seconds; this.VelocityZ += this.AccelerationZ * seconds; // update position based on velocity this.PositionX += this.VelocityX * seconds; this.PositionY += this.VelocityY * seconds; this.PositionZ += this.VelocityZ * seconds; // update rotational velocity based on rotational acceleration this.RotationVelocityX += this.RotationAccelerationX * seconds; this.RotationVelocityY += this.RotationAccelerationY * seconds; this.RotationVelocityZ += this.RotationAccelerationZ * seconds; // update rotation based on rotational velocity this.RotationX += this.RotationVelocityX * seconds; this.RotationY += this.RotationVelocityY * seconds; this.RotationZ += this.RotationVelocityZ * seconds; Matrix translation = Matrix.CreateTranslation(PositionX, PositionY, PositionZ); Matrix rotation = Matrix.CreateRotationX(RotationX) * Matrix.CreateRotationY(RotationY) * Matrix.CreateRotationZ(RotationZ); model.Root.Transform = rotation * translation * world; model.CopyAbsoluteBoneTransformsTo(boneTransforms); foreach (ModelMesh mesh in model.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.World = boneTransforms[mesh.ParentBone.Index]; effect.View = view; effect.Projection = projection; effect.EnableDefaultLighting(); } mesh.Draw(); } }

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• Using Solaris zfs + iscsi targets with Oracle VM

  - by wim.coekaerts

  I was playing with my Oracle VM setup and needed some shared storage that was block based. I did not have a storage array available but I did have a solaris box, that I use for Oracle VDI, available. I set up a few iscsi targets on this solaris server and exported them to my 2 Oracle VM servers. Here's how I did this : (1) On the solaris side : # zpool list NAME SIZE USED AVAIL CAP HEALTH ALTROOT rpool 544G 129G 415G 23% ONLINE - I just have a simple zpool, called rpool, on this box. It has plenty of space available for my needs. So I will use rpool and I will create 5 50gb vols : zfs create -V 50G rpool/ovm1 zfs create -V 50G rpool/ovm2 zfs create -V 50G rpool/ovm3 zfs create -V 50G rpool/ovm4 zfs create -V 50G rpool/ovm5 I want to use these volumes for iscsi so I have to enable them as shared iscsi devices : zfs set shareiscsi=on rpool/ovm1 zfs set shareiscsi=on rpool/ovm2 zfs set shareiscsi=on rpool/ovm3 zfs set shareiscsi=on rpool/ovm4 zfs set shareiscsi=on rpool/ovm5 The command iscsitadm list target should list these devices so make sure they show up. # iscsitadm list target Target: rpool/ovm1 iSCSI Name: iqn.1986-03.com.sun:02:896c766c-0943-4da5-d47e-9575b5a0be36 Connections: 2 Target: rpool/ovm2 iSCSI Name: iqn.1986-03.com.sun:02:a3116b46-73e0-e8c2-e80c-9a4f71aff069 Connections: 2 Target: rpool/ovm3 iSCSI Name: iqn.1986-03.com.sun:02:a838c400-2730-c0d6-f2c2-ee186a0261c1 Connections: 2 Target: rpool/ovm4 iSCSI Name: iqn.1986-03.com.sun:02:2e046afb-d66d-4f3f-c5de-8115e0ddd931 Connections: 2 Target: rpool/ovm5 iSCSI Name: iqn.1986-03.com.sun:02:66109fbe-81ac-ef05-f85e-ab8c1f34cb43 Connections: 2 At this point I want to make sure that I have some access control on these devices. To make it easier, I will create an alias for my 2 servers and use the alias for the ACL. get the iqn from the 2 servers on my 2 ovm servers (wcoekaer-srv1, wcoekaer-srv2) get the content of /etc/iscsi/initiatorname.iscsi (for each server) InitiatorName=iqn.1986-03.com.sun:01:2a7526f0ffff On the solaris side create the aliases : iscsitadm create initiator -n iqn.1986-03.com.sun:01:2a7526f0ffff wcoekaer-srv1 iscsitadm create initiator -n iqn.1986-03.com.sun:01:e31b08110f1 wcoekaer-srv5 Add the ACL to the targets : iscsitadm modify target -l wcoekaer-srv1 rpool/ovm1 iscsitadm modify target -l wcoekaer-srv1 rpool/ovm2 iscsitadm modify target -l wcoekaer-srv1 rpool/ovm3 iscsitadm modify target -l wcoekaer-srv1 rpool/ovm4 iscsitadm modify target -l wcoekaer-srv1 rpool/ovm5 iscsitadm modify target -l wcoekaer-srv5 rpool/ovm1 iscsitadm modify target -l wcoekaer-srv5 rpool/ovm2 iscsitadm modify target -l wcoekaer-srv5 rpool/ovm3 iscsitadm modify target -l wcoekaer-srv5 rpool/ovm4 iscsitadm modify target -l wcoekaer-srv5 rpool/ovm5 (2) the Oracle VM side On each server just do 2 simple things : # iscsiadm -m discovery -t sendtargets -p ca-vdi1 where ca-vdi1 is my solaris server name # service iscsi restart When I do cat /proc/partitions on my servers I will see the devices show up # cat /proc/partitions major minor #blocks name 8 0 160836480 sda 8 1 104391 sda1 8 2 3148740 sda2 8 3 1052257 sda3 253 0 6377804 dm-0 253 1 6377804 dm-1 253 2 6377804 dm-2 8 16 52428800 sdb 8 32 52428800 sdc 8 48 52428800 sdd 8 80 52428800 sdf 8 64 52428800 sde These 5 new devices sd[b..f] are shared storage for Oracle VM and can be used to pass through to the VM's as phy: devices or put ocfs2 on it and use as shared filesystem storage for dom0 repositories. I am setting up an 11gR2 rac template (the cool stuff Saar did) so I am using my devices to create a 2 node RAC cluster with phy: devices.

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• Detect Unicode Usage in SQL Column

  One optimization you can make to a SQL table that is overly large is to change from nvarchar (or nchar) to varchar (or char).  Doing so will cut the size used by the data in half, from 2 bytes per character (+ 2 bytes of overhead for varchar) to only 1 byte per character.  However, you will lose the ability to store Unicode characters, such as those used by many non-English alphabets.  If the tables are storing user-input, and your application is or might one day be used internationally, its likely that using Unicode for your characters is a good thing.  However, if instead the data is being generated by your application itself or your development team (such as lookup data), and you can be certain that Unicode character sets are not required, then switching such columns to varchar/char can be an easy improvement to make. Avoid Premature Optimization If you are working with a lookup table that has a small number of rows, and is only ever referenced in the application by its numeric ID column, then you wont see any benefit to using varchar vs. nvarchar.  More generally, for small tables, you wont see any significant benefit.  Thus, if you have a general policy in place to use nvarchar/nchar because it offers more flexibility, do not take this post as a recommendation to go against this policy anywhere you can.  You really only want to act on measurable evidence that suggests that using Unicode is resulting in a problem, and that you wont lose anything by switching to varchar/char. Obviously the main reason to make this change is to reduce the amount of space required by each row.  This in turn affects how many rows SQL Server can page through at a time, and can also impact index size and how much disk I/O is required to respond to queries, etc.  If for example you have a table with 100 million records in it and this table has a column of type nchar(5), this column will use 5 * 2 = 10 bytes per row, and with 100M rows that works out to 10 bytes * 100 million = 1000 MBytes or 1GB.  If it turns out that this column only ever stores ASCII characters, then changing it to char(5) would reduce this to 5*1 = 5 bytes per row, and only 500MB.  Of course, if it turns out that it only ever stores the values true and false then you could go further and replace it with a bit data type which uses only 1 byte per row (100MB  total). Detecting Whether Unicode Is In Use So by now you think that you have a problem and that it might be alleviated by switching some columns from nvarchar/nchar to varchar/char but youre not sure whether youre currently using Unicode in these columns.  By definition, you should only be thinking about this for a column that has a lot of rows in it, since the benefits just arent there for a small table, so you cant just eyeball it and look for any non-ASCII characters.  Instead, you need a query.  Its actually very simple: SELECT DISTINCT(CategoryName)FROM CategoriesWHERE CategoryName <> CONVERT(varchar, CategoryName) Summary Gregg Stark for the tip. Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Mastering snow and Java development at jDays in Gothenburg

  - by JavaCecilia

  Last weekend, I took the train from Stockholm to Gothenburg to attend and present at the new Java developer conference jDays. It was professionally arranged in the Swedish exhibition hall close to the amusement park Liseberg and we got a great deal out of the top-level presenters and hallway discussions. Understanding and Improving Your Java Process Our main purpose was to spread information on JVM and our monitoring tools for Java processes, so I held a crash course in the most important terms and concepts if you want to affect the performance of your Java process. From the beginning - the JVM specification to interpretation of heap usage graphs. For correct analysis, you also need to understand something about process memory - you need space for the Java heap (-Xms for initial size and -Xmx for max heap size), but the process memory also contain the thread stacks (to a size of -Xss), JVM internal data structures used for keeping track of Java objects on the heap, method compilation/optimization, native libraries, etc. If you get long pause times, make sure to monitor your application, see the allocation rate and frequency of pause times.My colleague Klara Ward then held a presentation on the Java Mission Control product, the profiling and diagnostics tools suite for HotSpot, coming soon. The room was packed and very appreciated, Klara demonstrated four different scenarios, e.g. how to diagnose and fix latencies due to lock contention for logging.My German colleague, OpenJDK ambassador Dalibor Topic travelled to Sweden to do the second keynote on "Make the Future Java". He let us in on the coming features and roadmaps of Java, now delivering major versions on a two-year schedule (Java 7 2011, Java 8 2013, etc). Also letting us in on where to download early versions of 8, to report problems early on. Software Development in teams Being a scout leader, I'm drilled in different team building and workshop techniques, creating strong groups - of course, I had to attend Henrik Berglund's session on building successful teams. He spoke about the importance of clear goals, autonomy and agreed processes. Thomas Sundberg ended the conference by doing live remote pair programming with Alex in Rumania and a concrete tips for people wanting to try it out (for local collaboration, remember to wash and change clothes). Memory Master Keynote The conference keynote was delivered by the Swedish memory master Mattias Ribbing, showing off by remembering the order of a deck of cards he'd seen once. He made it interactive by forcing the audience to learn a memory mastering technique of remembering ten ordered things by heart, asking us to shout out the order backwards and we made it! I desperately need this - bought the book, will get back on the subject. Continuous Delivery The most impressive presenter was Axel Fontaine on Continuous Delivery. Very well prepared slides with key images of his message and moved about the stage like a rock star. The topic is of course highly interesting, how to create an infrastructure enabling immediate feedback to developers and ability to release your product several times per day. Tomek Kaczanowski delivered a funny and useful presentation on good and bad tests, providing comic relief with poorly written tests and the useful rules of thumb how to rewrite them. To conclude, we had a great time and hope to see you at jDays next year :)

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• Omni-directional light shadow mapping with cubemaps in WebGL

  - by Winged

  First of all I must say, that I have read a lot of posts describing an usage of cubemaps, but I'm still confused about how to use them. My goal is to achieve a simple omni-directional (point) light type shading in my WebGL application. I know that there is a lot more techniques (like using Two-Hemispheres or Camera Space Shadow Mapping) which are way more efficient, but for an educational purpose cubemaps are my primary goal. Till now, I have adapted a simple shadow mapping which works with spotlights (with one exception: I don't know how to cut off the glitchy part beyond the reach of a single shadow map texture): glitchy shadow mapping<<< So for now, this is how I understand the usage of cubemaps in shadow mapping: Setup a framebuffer (in case of cubemaps - 6 framebuffers; 6 instead of 1 because every usage of framebufferTexture2D slows down an execution which is nicely described here <<<) and a texture cubemap. Also in WebGL depth components are not well supported, so I need to render it to RGBA first. this.texture = gl.createTexture(); gl.bindTexture(gl.TEXTURE_CUBE_MAP, this.texture); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MAG_FILTER, gl.LINEAR); for (var face = 0; face < 6; face++) gl.texImage2D(gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, 0, gl.RGBA, this.size, this.size, 0, gl.RGBA, gl.UNSIGNED_BYTE, null); gl.bindTexture(gl.TEXTURE_CUBE_MAP, null); this.framebuffer = []; for (face = 0; face < 6; face++) { this.framebuffer[face] = gl.createFramebuffer(); gl.bindFramebuffer(gl.FRAMEBUFFER, this.framebuffer[face]); gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, this.texture, 0); gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, this.depthbuffer); var e = gl.checkFramebufferStatus(gl.FRAMEBUFFER); // Check for errors if (e !== gl.FRAMEBUFFER_COMPLETE) throw "Cubemap framebuffer object is incomplete: " + e.toString(); } Setup the light and the camera (I'm not sure if should I store all of 6 view matrices and send them to shaders later, or is there a way to do it with just one view matrix). Render the scene 6 times from the light's position, each time in another direction (X, -X, Y, -Y, Z, -Z) for (var face = 0; face < 6; face++) { gl.bindFramebuffer(gl.FRAMEBUFFER, shadow.buffer.framebuffer[face]); gl.viewport(0, 0, shadow.buffer.size, shadow.buffer.size); gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); camera.lookAt( light.position.add( cubeMapDirections[face] ) ); scene.draw(shadow.program); } In a second pass, calculate the projection a a current vertex using light's projection and view matrix. Now I don't know If should I calculate 6 of them, because of 6 faces of a cubemap. ScaleMatrix pushes the projected vertex into the 0.0 - 1.0 region. vDepthPosition = ScaleMatrix * uPMatrixFromLight * uVMatrixFromLight * vWorldVertex; In a fragment shader calculate the distance between the current vertex and the light position and check if it's deeper then the depth information read from earlier rendered shadow map. I know how to do it with a 2D Texture, but I have no idea how should I use cubemap texture here. I have read that texture lookups into cubemaps are performed by a normal vector instead of a UV coordinate. What vector should I use? Just a normalized vector pointing to the current vertex? For now, my code for this part looks like this (not working yet): float shadow = 1.0; vec3 depth = vDepthPosition.xyz / vDepthPosition.w; depth.z = length(vWorldVertex.xyz - uLightPosition) * linearDepthConstant; float shadowDepth = unpack(textureCube(uDepthMapSampler, vWorldVertex.xyz)); if (depth.z > shadowDepth) shadow = 0.5; Could you give me some hints or examples (preferably in WebGL code) how I should build it?

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• Universities 2030: Learning from the Past to Anticipate the Future

  - by Mohit Phogat

  What will the landscape of international higher education look like a generation from now? What challenges and opportunities lie ahead for universities, especially “global” research universities? And what can university leaders do to prepare for the major social, economic, and political changes—both foreseen and unforeseen—that may be on the horizon? The nine essays in this collection proceed on the premise that one way to envision “the global university” of the future is to explore how earlier generations of university leaders prepared for “global” change—or at least responded to change—in the past. As the essays in this collection attest, many of the patterns associated with contemporary “globalization” or “internationalization” are not new; similar processes have been underway for a long time (some would say for centuries).[1] A comparative-historical look at universities’ responses to global change can help today’s higher-education leaders prepare for the future. Written by leading historians of higher education from around the world, these nine essays identify “key moments” in the internationalization of higher education: moments when universities and university leaders responded to new historical circumstances by reorienting their relationship with the broader world. Covering more than a century of change—from the late nineteenth century to the early twenty-first—they explore different approaches to internationalization across Europe, Asia, Australia, North America, and South America. Notably, while the choice of historical eras was left entirely open, the essays converged around four periods: the 1880s and the international extension of the “modern research university” model; the 1930s and universities’ attempts to cope with international financial and political crises; the 1960s and universities’ role in an emerging postcolonial international development apparatus; and the 2000s and the rise of neoliberal efforts to reform universities in the name of international economic “competitiveness.” Each of these four periods saw universities adopt new approaches to internationalization in response to major historical-structural changes, and each has clear parallels to today. Among the most important historical-structural challenges that universities confronted were: (1) fluctuating enrollments and funding resources associated with global economic booms and busts; (2) new modes of transportation and communication that facilitated mobility (among students, scholars, and knowledge itself); (3) increasing demands for applied science, technical expertise, and commercial innovation; and (4) ideological reconfigurations accompanying regime changes (e.g., from one internal regime to another, from colonialism to postcolonialism, from the cold war to globalized capitalism, etc.). Like universities today, universities in the past responded to major historical-structural changes by internationalizing: by joining forces across space to meet new expectations and solve problems on an ever-widening scale. Approaches to internationalization have typically built on prior cultural or institutional ties. In general, only when the benefits of existing ties had been exhausted did universities reach out to foreign (or less familiar) partners. As one might expect, this process of “reaching out” has stretched universities’ traditional cultural, political, and/or intellectual bonds and has invariably presented challenges, particularly when national priorities have differed—for example, with respect to curricular programs, governance structures, norms of academic freedom, etc. Strategies of university internationalization that either ignore or downplay cultural, political, or intellectual differences often fail, especially when the pursuit of new international connections is perceived to weaken national ties. If the essays in this collection agree on anything, they agree that approaches to internationalization that seem to “de-nationalize” the university usually do not succeed (at least not for long). Please continue reading the other essays at http://globalhighered.wordpress.com/

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• Give a session on C++ AMP – here is how

  - by Daniel Moth

  Ever since presenting on C++ AMP at the AMD Fusion conference in June, then the Gamefest conference in August, and the BUILD conference in September, I've had numerous requests about my material from folks that want to re-deliver the same session. The C++ AMP session I put together has evolved over the 3 presentations to its final form that I used at BUILD, so that is the one I recommend you base yours on. Please get the slides and the recording from channel9 (I'll refer to slide numbers below). This is how I've been presenting the C++ AMP session: Context (slide 3, 04:18-08:18) Start with a demo, on my dual-GPU machine. I've been using the N-Body sample (for VS 11 Developer Preview). (slide 4) Use an nvidia slide that has additional examples of performance improvements that customers enjoy with heterogeneous computing. (slide 5) Talk a bit about the differences today between CPU and GPU hardware, leading to the fact that these will continue to co-exist and that GPUs are great for data parallel algorithms, but not much else today. One is a jack of all trades and the other is a number cruncher. (slide 6) Use the APU example from amd, as one indication that the hardware space is still in motion, emphasizing that the C++ AMP solution is a data parallel API, not a GPU API. It has a future proof design for hardware we have yet to see. (slide 7) Provide more meta-data, as blogged about when I first introduced C++ AMP. Code (slide 9-11) Introduce C++ AMP coding with a simplistic array-addition algorithm – the slides speak for themselves. (slide 12-13) index<N>, extent<N>, and grid<N>. (Slide 14-16) array<T,N>, array_view<T,N> and comparison between them. (Slide 17) parallel_for_each. (slide 18, 21) restrict. (slide 19-20) actual restrictions of restrict(direct3d) – the slides speak for themselves. (slide 22) bring it altogether with a matrix multiplication example. (slide 23-24) accelerator, and accelerator_view. (slide 26-29) Introduce tiling incl. tiled matrix multiplication [tiling probably deserves a whole session instead of 6 minutes!]. IDE (slide 34,37) Briefly touch on the concurrency visualizer. It supports GPU profiling, but enhancements specific to C++ AMP we hope will come at the Beta timeframe, which is when I'll be spending more time talking about it. (slide 35-36, 51:54-59:16) Demonstrate the GPU debugging experience in VS 11. Summary (slide 39) Re-iterate some of the points of slide 7, and add the point that the C++ AMP spec will be open for other compiler vendors to implement, even on other platforms (in fact, Microsoft is actively working on that). (slide 40) Links to content – see slide – including where all your questions should go: http://social.msdn.microsoft.com/Forums/en/parallelcppnative/threads.   "But I don't have time for a full blown session, I only need 2 (or just 1, or 3) C++ AMP slides to use in my session on related topic X" If all you want is a small number of slides, you can take some from the session above and customize them. But because I am so nice, I have created some slides for you, including talking points in the notes section. Download them here. Comments about this post by Daniel Moth welcome at the original blog.

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• Java EE 7 Roadmap

  - by Linda DeMichiel

  The Java EE 6 Platform, released in December 2009, has seen great uptake from the community with its POJO-based programming model, lightweight Web Profile, and extension points. There are now 13 Java EE 6 compliant appserver implementations today! When we announced the Java EE 7 JSR back in early 2011, our plans were that we would release it by Q4 2012. This target date was slightly over three years after the release of Java EE 6, but at the same time it meant that we had less than two years to complete a fairly comprehensive agenda — to continue to invest in significant enhancements in simplification, usability, and functionality in updated versions of the JSRs that are currently part of the platform; to introduce new JSRs that reflect emerging needs in the community; and to add support for use in cloud environments. We have since announced a minor adjustment in our dates (to the spring of 2013) in order to accommodate the inclusion of JSRs of importance to the community, such as Web Sockets and JSON-P. At this point, however, we have to make a choice. Despite our best intentions, our progress has been slow on the cloud side of our agenda. Partially this has been due to a lack of maturity in the space for provisioning, multi-tenancy, elasticity, and the deployment of applications in the cloud. And partially it is due to our conservative approach in trying to get things "right" in view of limited industry experience in the cloud area when we started this work. Because of this, we believe that providing solid support for standardized PaaS-based programming and multi-tenancy would delay the release of Java EE 7 until the spring of 2014 — that is, two years from now and over a year behind schedule. In our opinion, that is way too long. We have therefore proposed to the Java EE 7 Expert Group that we adjust our course of action — namely, stick to our current target release dates, and defer the remaining aspects of our agenda for PaaS enablement and multi-tenancy support to Java EE 8. Of course, we continue to believe that Java EE is well-suited for use in the cloud, although such use might not be quite ready for full standardization. Even today, without Java EE 7, Java EE vendors such as Oracle, Red Hat, IBM, and CloudBees have begun to offer the ability to run Java EE applications in the cloud. Deferring the remaining cloud-oriented aspects of our agenda has several important advantages: It allows Java EE Platform vendors to gain more experience with their implementations in this area and thus helps us avoid risks entailed by trying to standardize prematurely in an emerging area. It means that the community won't need to wait longer for those features that are ready at the cost of those features that need more time. Because we have already laid some of the infrastructure for cloud support in Java EE 7, including resource definition metadata, improved security configuration, JPA schema generation, etc., it will allow us to expedite a Java EE 8 release. We therefore plan to target the Java EE 8 Platform release for the spring of 2015. This shift in the scope of Java EE 7 allows us to better retain our focus on enhancements in simplification and usability and to deliver on schedule those features that have been most requested by developers. These include the support for HTML 5 in the form of Web Sockets and JSON-P; the simplified JMS 2.0 APIs; improved Managed Bean alignment, including transactional interceptors; the JAX-RS 2.0 client API; support for method-level validation; a much more comprehensive expression language; and more. We feel strongly that this is the right thing to do, and we hope that you will support us in this proposed direction.

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• Multithreading 2D gravity calculations

  - by Postman

  I'm building a space exploration game and I've currently started working on gravity ( In C# with XNA). The gravity still needs tweaking, but before I can do that, I need to address some performance issues with my physics calculations. This is using 100 objects, normally rendering 1000 of them with no physics calculations gets well over 300 FPS (which is my FPS cap), but any more than 10 or so objects brings the game (and the single thread it runs on) to its knees when doing physics calculations. I checked my thread usage and the first thread was killing itself from all the work, so I figured I just needed to do the physics calculation on another thread. However when I try to run the Gravity.cs class's Update method on another thread, even if Gravity's Update method has nothing in it, the game is still down to 2 FPS. Gravity.cs public void Update() { foreach (KeyValuePair<string, Entity> e in entityEngine.Entities) { Vector2 Force = new Vector2(); foreach (KeyValuePair<string, Entity> e2 in entityEngine.Entities) { if (e2.Key != e.Key) { float distance = Vector2.Distance(entityEngine.Entities[e.Key].Position, entityEngine.Entities[e2.Key].Position); if (distance > (entityEngine.Entities[e.Key].Texture.Width / 2 + entityEngine.Entities[e2.Key].Texture.Width / 2)) { double angle = Math.Atan2(entityEngine.Entities[e2.Key].Position.Y - entityEngine.Entities[e.Key].Position.Y, entityEngine.Entities[e2.Key].Position.X - entityEngine.Entities[e.Key].Position.X); float mult = 0.1f * (entityEngine.Entities[e.Key].Mass * entityEngine.Entities[e2.Key].Mass) / distance * distance; Vector2 VecForce = new Vector2((float)Math.Cos(angle), (float)Math.Sin(angle)); VecForce.Normalize(); Force = Vector2.Add(Force, VecForce * mult); } } } entityEngine.Entities[e.Key].Position += Force; } } Yeah, I know. It's a nested foreach loop, but I don't know how else to do the gravity calculation, and this seems to work, it's just so intensive that it needs its own thread. (Even if someone knows a super efficient way to do these calculations, I'd still like to know how I COULD do it on multiple threads instead) EntityEngine.cs (manages an instance of Gravity.cs) public class EntityEngine { public Dictionary<string, Entity> Entities = new Dictionary<string, Entity>(); public Gravity gravity; private Thread T; public EntityEngine() { gravity = new Gravity(this); } public void Update() { foreach (KeyValuePair<string, Entity> e in Entities) { Entities[e.Key].Update(); } T = new Thread(new ThreadStart(gravity.Update)); T.IsBackground = true; T.Start(); } } EntityEngine is created in Game1.cs, and its Update() method is called within Game1.cs. I need my physics calculation in Gravity.cs to run every time the game updates, in a separate thread so that the calculation doesn't slow the game down to horribly low (0-2) FPS. How would I go about making this threading work? (any suggestions for an improved Planetary Gravity system are welcome if anyone has them) I'm also not looking for a lesson in why I shouldn't use threading or the dangers of using it incorrectly, I'm looking for a straight answer on how to do it. I've already spent an hour googling this very question with little results that I understood or were helpful. I don't mean to come off rude, but it always seems hard as a programming noob to get a straight meaningful answer, I usually rather get an answer so complex I'd easily be able to solve my issue if I understood it, or someone saying why I shouldn't do what I want to do and offering no alternatives (that are helpful). Thank you for the help!

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• AI to move custom-shaped spaceships (shape affecting movement behaviour)

  - by kaoD

  I'm designing a networked turn based 3D-6DOF space fleet combat strategy game which relies heavily on ship customization. Let me explain the game a bit, since you need to know a bit about it to set the question. What I aim for is the ability to create your own fleet of ships with custom shapes and attached modules (propellers, tractor beams...) which would give advantages and disadvantages to each ship, so you have lots of different fleet distributions. E.g., long ship with two propellers at the side would let the ship spin around that plane easily, bigger ships would move slowly unless you place lots of propellers at the back (therefore spending more "construction" points and energy when moving, and it will only move fast towards that direction.) I plan to balance all the game around this feature. The game would revolve around two phases: orders and combat phase. During the orders phase, you command the different ships. When all players finish the order phase, the combat phase begins and the ship orders get resolved in real-time for some time, then the action pauses and there's a new orders phase. The problem comes when I think about player input. To move a ship, you need to turn on or off different propellers if you want to steer, travel forward, brake, rotate in place... These propellers don't have to work at their whole power, so you can achieve more movement combinations with less propellers. I think this approach is a bit boring. The player doesn't want to fiddle with motors or anything, you just want to MOVE and KILL. The way I intend the player to give orders to these ships is by a destination and a rotation, and then the AI would calculate the correct propeller power to achive that movement and rotation. Propulsion doesn't have to be the same throught the entire turn calculation (after the orders have been given) so it would be cool if the ships reacted as they move, adjusting the power of the propellers for their needs dynamically, but it may be too hard to implement and it's not really needed for the game to work. In both cases, how would that AI decide which propellers to activate for the best (or at least not worst) trajectory to be achieved? I though about some approaches: Learning AI: The ship types would learn about their movement by trial and error, adjusting their behaviour with more uses, and finally becoming "smart". I don't want to get involved THAT far in AI coding, and I think it can be frustrating for the player (even if you can let it learn without playing.) Pre-calculated timestep movement: Upon ship creation, ALL possible movements are calculated for each propeller configuration and power for a given delta-time. Memory intensive, ugly, bad. Pre-calculated trajectories: The same as above but not for each delta-time but the whole trajectory, which would then be fitted as much as possible. Requires a fixed propeller configuration for the whole combat phase and is still memory intensive, ugly and bad. Continuous brute forcing: The AI continously checks ALL possible propeller configurations throughout the entire combat phase, precalculates a few time steps and decides which is the best one based on that. Con: what's good now might not be that good later, and it's too CPU intensive, ugly, and bad too. Single brute forcing: Same as above, but only brute forcing at the beginning of the simulation, so it needs constant propeller configuration throughout the entire combat phase. Coninuous angle check: This is not a full movement method, but maybe a way to discard "stupid" propeller configurations. Given the current propeller's normal vector and the final one, you can approximate the power needed for the propeller based on the angle. You must do this continuously throughout the whole combat phase. I figured this one out recently so I didn't put in too much thought. A priori, it has the "what's good now might not be that good later" drawback too, and it doesn't care about the other propellers which may act together to make a better propelling configuration. I'm really stuck here. Any ideas?

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• Why won't my Broadcom BCM4312 LP-PHY work with the STA driver?

  - by Jackson Taylor

  I tried the steps here for a 4312: https://help.ubuntu.com/community/WifiDocs/Driver/bcm43xx Both of these: sudo modprobe -r b43 ssb wl sudo modprobe wl return: FATAL: Module wl not found. FATAL: Error running install command for wl (this one is only for the second one actually) I tried the broadcom-sta, didn't work. What's confusing is down below in the next steps for STA with internet access it says to use the bcmwl one. So I install that and it succeeds but with some errors: sudo apt-get install bcmwl-kernel-source Reading package lists... Done Building dependency tree Reading state information... Done The following package was automatically installed and is no longer required: module-assistant Use 'apt-get autoremove' to remove it. The following NEW packages will be installed: bcmwl-kernel-source 0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. Need to get 0 B/1,181 kB of archives. After this operation, 3,609 kB of additional disk space will be used. Selecting previously unselected package bcmwl-kernel-source. (Reading database ... 168005 files and directories currently installed.) Unpacking bcmwl-kernel-source (from .../bcmwl-kernel-source_5.100.82.112+bdcom-0ubuntu3_amd64.deb) ... Setting up bcmwl-kernel-source (5.100.82.112+bdcom-0ubuntu3) ... Loading new bcmwl-5.100.82.112+bdcom DKMS files... Building only for 3.5.0-21-generic Building for architecture x86_64 Module build for the currently running kernel was skipped since the kernel source for this kernel does not seem to be installed. ERROR: Module b43 does not exist in /proc/modules ERROR: Module b43legacy does not exist in /proc/modules ERROR: Module ssb does not exist in /proc/modules ERROR: Module bcm43xx does not exist in /proc/modules ERROR: Module brcm80211 does not exist in /proc/modules ERROR: Module brcmfmac does not exist in /proc/modules ERROR: Module brcmsmac does not exist in /proc/modules ERROR: Module bcma does not exist in /proc/modules FATAL: Module wl not found. FATAL: Error running install command for wl update-initramfs: deferring update (trigger activated) Processing triggers for initramfs-tools ... update-initramfs: Generating /boot/initrd.img-3.5.0-21-generic jtaylor991@jtaylor991-whiteHP:~$ sudo modprobe wl FATAL: Module wl not found. FATAL: Error running install command for wl Then I do the modprobe wl commands listed above and it gives the above listed errors. It didn't work with the broadcom-sta driver either. I installed the b43 ones but nothing happened, and I don't know why so those are still installed. firmware-b43legacy-installer, b43-fwcutter and firmware-b43-lpphy-installer (yes it is a LP-PHY) are currently installed. If I go into System Settings Software Sources Additional Drivers it says "Using Broadcom 802.11 Linux STA wireless driver source from bcmwl-kernel-source (proprietary) But bcmwl-kernel-source isn't installed. I could try again but I remember rebooting and it still said this. What's funny is it found wireless networks during the Ubuntu setup/installation, I don't remember if I got it to connect or not though. I think it kept asking for a password when I put it in (yes it was right I showed password and looked at it) so I just ignored it. But right now the Enable Wireless option in the top right is just gone, it's just Enable Networking and I'm on ethernet on this HP Pavilion dv4-1435dx right here. If I run rfkill list it shows: 0: hp-wifi: Wireless LAN Soft blocked: no Hard blocked: no It was hard blocked at the beginning but unblocking it makes no change. Also it's a touch sensitive button, and it appears to be always orange no matter if it's enabled or not because when I touch it the hard blocked changes between yes and no in rfkill list. I think it was blue for a minute at one point. What is going on?!?! Help me! Lol, thanks for any and all of your time guys. Oh yeah this is Ubuntu 12.10 fresh install.

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