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• Juggling with JDKs on Apple OS X

  - by Blueberry Coder

  I recently got a shiny new MacBook Pro to help me support our ADF Mobile customers. It is really a wonderful piece of hardware, although I am still adjusting to Apple's peculiar keyboard layout. Did you know, for example, that the « delete » key actually performs a « backspace »? But I disgress... As you may know, ADF Mobile development still requires JDeveloper 11gR2, which in turn runs on Java 6. On the other hand, JDeveloper 12c needs JDK 7. I wanted to install both versions, and wasn't sure how to do it.   If you remember, I explained in a previous blog entry how to install JDeveloper 11gR2 on Apple's OS X. The trick was to use the /usr/libexec/java_home command in order to invoke the proper JDK. In this case, I could have done the same thing; the two JDKs can coexist without any problems, since they install in completely different locations. But I wanted more than just installing JDeveloper. I wanted to be able to select my JDK when using the command line as well. On Windows, this is easy, since I keep all my JDKs in a central location. I simply have to move to the appropriate folder or type the folder name in the command I want to execute. Problem is, on OS X, the paths to the JDKs are... let's say convoluted.  Here is the one for Java 6. /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home The Java 7 path is not better, just different. /Library/Java/JavaVirtualMachines/jdk1.7.0_45.jdk/Contents/Home Intuitive, isn't it? Clearly, I needed something better... On OS X, the default command shell is bash. It is possible to configure the shell environment by creating a file named « .profile » in a user's home folder. Thus, I created such a file and put the following inside: export JAVA_7_HOME=$(/usr/libexec/java_home -v1.7) export JAVA_6_HOME=$(/usr/libexec/java_home -v1.6) export JAVA_HOME=$JAVA_7_HOME alias java6='export JAVA_HOME=$JAVA_6_HOME' alias java7='export JAVA_HOME=$JAVA_7_HOME'  The first two lines retrieve the current paths for Java 7 and Java 6 and store them in two environment variables. The third line marks Java 7 as the default. The last two lines create command aliases. Thus, when I type java6, the value for JAVA_HOME is set to JAVA_6_HOME, for example.  I now have an environment which works even better than the one I have on Windows, since I can change my active JDK on a whim. Here a sample, fresh from my terminal window. fdesbien-mac:~ fdesbien$ java6 fdesbien-mac:~ fdesbien$ java -version java version "1.6.0_65" Java(TM) SE Runtime Environment (build 1.6.0_65-b14-462-11M4609) Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-462, mixed mode) fdesbien-mac:~ fdesbien$ fdesbien-mac:~ fdesbien$ java7 fdesbien-mac:~ fdesbien$ java -version java version "1.7.0_45" Java(TM) SE Runtime Environment (build 1.7.0_45-b18) Java HotSpot(TM) 64-Bit Server VM (build 24.45-b08, mixed mode) fdesbien-mac:~ fdesbien$ Et voilà! Maximum flexibility without downsides, just I like it. 

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• Asynchrony in C# 5 (Part II)

  - by javarg

  This article is a continuation of the series of asynchronous features included in the new Async CTP preview for next versions of C# and VB. Check out Part I for more information. So, let’s continue with TPL Dataflow: Asynchronous functions TPL Dataflow Task based asynchronous Pattern Part II: TPL Dataflow Definition (by quote of Async CTP doc): “TPL Dataflow (TDF) is a new .NET library for building concurrent applications. It promotes actor/agent-oriented designs through primitives for in-process message passing, dataflow, and pipelining. TDF builds upon the APIs and scheduling infrastructure provided by the Task Parallel Library (TPL) in .NET 4, and integrates with the language support for asynchrony provided by C#, Visual Basic, and F#.” This means: data manipulation processed asynchronously. “TPL Dataflow is focused on providing building blocks for message passing and parallelizing CPU- and I/O-intensive applications”. Data manipulation is another hot area when designing asynchronous and parallel applications: how do you sync data access in a parallel environment? how do you avoid concurrency issues? how do you notify when data is available? how do you control how much data is waiting to be consumed? etc.  Dataflow Blocks TDF provides data and action processing blocks. Imagine having preconfigured data processing pipelines to choose from, depending on the type of behavior you want. The most basic block is the BufferBlock<T>, which provides an storage for some kind of data (instances of <T>). So, let’s review data processing blocks available. Blocks a categorized into three groups: Buffering Blocks Executor Blocks Joining Blocks Think of them as electronic circuitry components :).. 1. BufferBlock<T>: it is a FIFO (First in First Out) queue. You can Post data to it and then Receive it synchronously or asynchronously. It synchronizes data consumption for only one receiver at a time (you can have many receivers but only one will actually process it). 2. BroadcastBlock<T>: same FIFO queue for messages (instances of <T>) but link the receiving event to all consumers (it makes the data available for consumption to N number of consumers). The developer can provide a function to make a copy of the data if necessary. 3. WriteOnceBlock<T>: it stores only one value and once it’s been set, it can never be replaced or overwritten again (immutable after being set). As with BroadcastBlock<T>, all consumers can obtain a copy of the value. 4. ActionBlock<TInput>: this executor block allows us to define an operation to be executed when posting data to the queue. Thus, we must pass in a delegate/lambda when creating the block. Posting data will result in an execution of the delegate for each data in the queue. You could also specify how many parallel executions to allow (degree of parallelism). 5. TransformBlock<TInput, TOutput>: this is an executor block designed to transform each input, that is way it defines an output parameter. It ensures messages are processed and delivered in order. 6. TransformManyBlock<TInput, TOutput>: similar to TransformBlock but produces one or more outputs from each input. 7. BatchBlock<T>: combines N single items into one batch item (it buffers and batches inputs). 8. JoinBlock<T1, T2, …>: it generates tuples from all inputs (it aggregates inputs). Inputs could be of any type you want (T1, T2, etc.). 9. BatchJoinBlock<T1, T2, …>: aggregates tuples of collections. It generates collections for each type of input and then creates a tuple to contain each collection (Tuple<IList<T1>, IList<T2>>). Next time I will show some examples of usage for each TDF block. * Images taken from Microsoft’s Async CTP documentation.

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• how to keep display tick rate steady when using continuous collision detection?

  - by nas Ns

  (I've just found about this forum). I hope it is ok to repost my question again here. I posted this question at stackoverflow, but it looks like I might get better help here. Here is the question: I've implemented basic particles motion simulation with continuous collision detection. But there is small issue in display. Assume simple case of circles moving inside square. All elastic collisions. no firction. All motion is constant speed. No forces are involved, no gravity. So when a particle is moving, it is always moving at constant speed (in between collisions) What I do now is this: Let the simulation time step be 1 second (for example). This is the time step simulation is advanced before displaying the new state (unless there is a collision sooner than this). At start of each time step, time for the next collision between any particles or a particle with a wall is determined. Call this the TOC time; let’s say TOC was .5 seconds in this case. Since TOC is smaller than the standard time step, then the system is moved by TOC and the new system is displayed so that the new display shows any collisions as just taking place (say 2 circles just touched each other’s, or a circle just touched a wall) Next, the collision(s) are resolved (i.e. speeds updated, changed directions etc..). A new step is started. The same thing happens. Now assume there is no collision detected within the next 1 second (those 2 circles above will not be in collision any more, even though they are still touching, due to their speeds showing they are moving apart now), Hence, simulation time is advanced now by the full one second, the standard time step, and particles are moved on the screen using 1 second simulation time and new display is shown. You see what has just happened: One frame ran for .5 seconds, but the next frame runs for 1 second, may be the 3rd frame is displayed after 2 seconds, may be the 4th frame is displayed after 2.8 seconds (because TOC was .8 seconds then) and so on. What happens is that the motion of a particle on the screen appears to speed up or slow down, even though it is moving at constant speed and was not even involved in a collision. i.e. Looking at one particle on its own, I see it suddenly speeding up or slowing down, becuase another particle had hit a wall. This is because the display tick is not uniform. i.e. the frame rate update is changing, giving the false illusion that a particle is moving at non-constant speed while in fact it is moving at constant speed. The motion on the screen is not smooth, since the screen is not updating at constant rate. I am not able to figure how to fix this. If I want to show 2 particles at the moment of the collision, I must draw the screen at different times. Drawing the screen always at the same tick interval, results in seeing 2 particles before the collision, and then after the collision, and not just when they colliding, which looked bad when I tried it. So, how do real games handle this issue? How to display things in order to show collisions when it happen, yet keep the display tick constant? These 2 requirements seem to contradict each other’s.

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• HERMES Medical Solutions Helps Save Lives with MySQL

  - by Bertrand Matthelié

  Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Cambria","serif"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} HERMES Medical Solutions was established in 1976 in Stockholm, Sweden, and is a leading innovator in medical imaging hardware/software products for health care facilities worldwide. HERMES delivers a plethora of different medical imaging solutions to optimize hospital workflow. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Cambria","serif"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} HERMES advanced algorithms make it possible to detect the smallest changes under therapies important and necessary to optimize different therapeutic methods and doses. Challenges Fighting illness & disease requires state-of-the-art imaging modalities and software in order to diagnose accurately, stage disease appropriately and select the best treatment available. Selecting and implementing a new database platform that would deliver the needed performance, reliability, security and flexibility required by the high-end medical solutions offered by HERMES. Solution Decision to migrate from in-house database to an embedded SQL database powering the HERMES products, delivered either as software, integrated hardware and software solutions, or via the cloud in a software-as-a-service configuration. Evaluation of several databases and selection of MySQL based on its high performance, ease of use and integration, and low Total Cost of Ownership. On average, between 4 and 12 Terabytes of data are stored in MySQL databases underpinning the HERMES solutions. The data generated by each medical study is indeed stored during 10 years or more after the treatment was performed. MySQL-based HERMES systems also allow doctors worldwide to conduct new drug research projects leveraging the large amount of medical data collected. Hospitals and other HERMES customers worldwide highly value the “zero administration” capabilities and reliability of MySQL, enabling them to perform medical analysis without any downtime. Relying on MySQL as their embedded database, the HERMES team has been able to increase their focus on further developing their clinical applications. HERMES Medical Solutions could leverage the Oracle Financing payment plan to spread its investment over time and make the MySQL choice even more valuable. “MySQL has proven to be an excellent database choice for us. We offer high-end medical solutions, and MySQL delivers the reliability, security and performance such solutions require.” Jan Bertling, CEO.

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• How much am I worth hourly as a software/web developer? [closed]

  - by luckysmack

  I may be starting a new job very soon as a developer for both web and desktop software. The primary languages I will be using is ASP.NET with C# with some php for existing projects(I've already had one interview which went very well). The job deals primarily in advertising. But this is my first real job in the market, I have no degrees, but have some college time(~1yr). So I am primarily self taught. They are fully aware of my skill set and lack of degrees or certificates. I applied as an entry level developer. It will be a permanent and full time/hourly position, and not a per contract job. So since it my cherry job, im not really sure what to ask for. even though im self taught im pretty confident in my skills and know what im doing fairly well. I pick up on new concepts very well and find new things fairly easy to learn. Here is a very brief summary of my skills: PHP: ~2years C#/.NET: 2 months Python: Basics only. ~1 month OOP Familiarity: Great (1 year) MVC Familiarity: Great (1 year) PHP Frameworks used: CakePHP(6 months), Yii(3 months), Lithium(3 months) CMS Familiar with: Drupal(1.5 years), Wordpress(only basics) I also have ~2yrs experience in maintaining my own VPS server and the hassles all that entails (linux/debian) Pretty much all the above will be used at this job. Although I will be using C# a vast majority of the time. I only recently started learning it but am moving along fairly rapidly and its all going smooth as butter. So what have I built? I have one proprietary site built in drupal which is used an an order log for products, inventory, and their shipments. It is also able to process payments through paypal merchant services. I have worked on a handful of other small apps used here and there I'm not able to show but which worked fairly well (all in php using frameworks though). The business does fairly well and is far from a a typical corporate type environment. It is much closer to a small development studio. And it is based out of northern California. I don't know how/what more info I can give on them. I also want this to be able to be referenced by other people possibly so I am looking for general tips and ideas to get an answer as well. I had trouble finding a reasonable range on other websites which seemed to be either way to low, or showed what a veteran developer makes. I know this is a fairly subjective question, but it is difficult to get a reasonable answer or guesstimate anywhere else. Even if only a little bit help, its much appreciated. So as for the direct question, based on all this info (did I miss anything?), how much should I ask for hourly? How much am I worth as a software developer?

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• Test Drive for Partners on Oracle Endeca Information Discovery

  - by Mike.Hallett(at)Oracle-BI&EPM

  Normal 0 false false false EN-GB X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;} Specifically for Oracle Partners, this half-day hands-on workshop allows you to experience Information Discovery from Oracle in order to: Understand Information Discovery and how it compliments classic BI solutions Use Search and Guided Navigation to see how structured and unstructured information can be rapidly brought together to unlock hidden value Explore all of your data in any format and from any source including social media, market surveys and reports Lay the foundation for helping business users who need fast answers to new questions Experience the amazing performance of Endeca on Oracle's in memory Exalytics machine Agenda After an introduction to Oracle Endeca Information Discovery, follow a self-paced, supervised, hands-on tutorial where you will see how easy it is to: Use Guided Navigation and Search to explore structured and unstructured data Rapidly integrate new and changing data sources such as Social Media Build new Discovery user interfaces Rapidly respond to changing business needs and data environments And ask questions of Oracle's Business Analytics experts throughout When 14th March 2013, Registration 9:00 a.m. - finish by 1:00 p.m.      Normal 0 false false false EN-GB X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;} Register Now What: Oracle Endeca Information Discovery Test Drive Where: Oracle City Office, 1 South Place, London, EC2M 2RB

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• Ubuntu 12.04 Hp G72 Problem Installing proprietary wireless driver

  - by user69402

  I have a fresh Ubuntu 12.04 installed on HP G72 machine. In order for my wireless to work I need the proprietary driver installed - Broadcom STA wireless driver. Trying to install it from the System Settings gives me the error: "Sorry, installation of this driver failed. Please have a look at the log file for details: /var/log/jockey.log". So far I suspect the error to be caused by the bad "bcmwl-kernel-source" installation. What i tried: 1. remove "bcmwl-kernel-source" 2. install "bcmwl-kernel-source" installation through the terminal ends with "error code (1)". I would greatly appreciate any help Here is everything that the terminal returns: Reading package lists... Done Building dependency tree Reading state information... Done 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/1,151 kB of archives. After this operation, 3,514 kB of additional disk space will be used. Selecting previously unselected package bcmwl-kernel-source. (Reading database ... 170331 files and directories currently installed.) Unpacking bcmwl-kernel-source (from .../bcmwl-kernel-source_5.100.82.38+bdcom-0ubuntu6.1_amd64.deb) ... Setting up bcmwl-kernel-source (5.100.82.38+bdcom-0ubuntu6.1) ... Loading new bcmwl-5.100.82.38+bdcom DKMS files... /usr/sbin/dkms: line 467: unset: POST_REMOVE$PRE_BUMLD': not a valid identifier /usr/sbin/dkms: line 467: unset:BUILD_E\CLUWIVE_ARCH': not a valid identifier /usr/sbin/dkms: line 467: unset: $': not a valid identifier /usr/sbin/dkms: line 467: unset:$': not a valid identifier /usr/sbin/dkms: line 467: unset: modules_conf_arra}': not a valid identifier /usr/sbin/dkms: line 467: unset:$': not a valid identifier /usr/sbin/dkms: line 467: unset: $': not a valid identifier /usr/sbin/dkms: line 467: unset:$': not a valid identifier /usr/sbin/dkms: line 467: unset: $': not a valid identifier /usr/sbin/dkms: line 467: unset:$': not a valid identifier /usr/sbin/dkms: line 467: unset: `$': not a valid identifier /usr/sbin/dkms: line 419: ${!POST_REMOVE$PRE_BUMLD[@]}: bad substitution /usr/sbin/dkms: line 419: ${!BUILD_E\CLUWIVE_ARCH[@]}: bad substitution /usr/sbin/dkms: line 419: ${!$[@]}: bad substitution /usr/sbin/dkms: line 419: ${!$[@]}: bad substitution /usr/sbin/dkms: line 419: ${!$[@]}: bad substitution /usr/sbin/dkms: line 419: ${!$[@]}: bad substitution /usr/sbin/dkms: line 419: ${!$[@]}: bad substitution /usr/sbin/dkms: line 419: ${!$[@]}: bad substitution /usr/sbin/dkms: line 419: ${!$[@]}: bad substitution /usr/sbin/dkms: line 419: ${!$[@]}: bad substitution malloc: ../bash/subst.c:3671: assertion botched free: start and end chunk sizes differ Aborting.../tmp/tmp.pEXTnftUfI: line 4: modules_conf_arra}[[@]}]=[[@]}]}: command not found dkms.conf: Error! No 'DEST_MODULE_LOCATION' directive specified for record #0. dkms.conf: Error! Directive 'DEST_MODULE_LOCATION' does not begin with '/kernel', '/updates', or '/extra' in record #0. dkms.conf: Error! No 'PACKAGE_VERSION' directive specified. Error! Bad conf file. File: /usr/src/bcmwl-5.100.82.38+bdcom/dkms.conf does not represent a valid dkms.conf file. dpkg: error processing bcmwl-kernel-source (--configure): subprocess installed post-installation script returned error exit status 8 Errors were encountered while processing: bcmwl-kernel-source E: Sub-process /usr/bin/dpkg returned an error code (1)

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• Getting Started with Cloud Computing

  - by juanlarios

  You’ve likely heard about how Office 365 and Windows Intune are great applications to get you started with Cloud Computing. Many of you emailed me asking for more info on what Cloud Computing is, including the distinction between "Public Cloud" and "Private Cloud". I want to address these questions and help you get started. Let's begin with a brief set of definitions and some places to find more info; however, an excellent place where you can always learn more about Cloud Computing is the Microsoft Virtual Academy. Public Cloud computing means that the infrastructure to run and manage the applications users are taking advantage of is run by someone else and not you. In other words, you do not buy the hardware or software to run your email or other services being used in your organization – that is done by someone else. Users simply connect to these services from their computers and you pay a monthly subscription fee for each user that is taking advantage of the service. Examples of Public Cloud services include Office 365, Windows Intune, Microsoft Dynamics CRM Online, Hotmail, and others. Private Cloud computing generally means that the hardware and software to run services used by your organization is run on your premises, with the ability for business groups to self-provision the services they need based on rules established by the IT department. Generally, Private Cloud implementations today are found in larger organizations but they are also viable for small and medium-sized businesses since they generally allow an automation of services and reduction in IT workloads when properly implemented. Having the right management tools, like System Center 2012, to implement and operate Private Cloud is important in order to be successful. So – how do you get started? The first step is to determine what makes the most sense to your organization. The nice thing is that you do not need to pick Public or Private Cloud – you can use elements of both where it makes sense for your business – the choice is yours. When you are ready to try and purchase Public Cloud technologies, the Microsoft Volume Licensing web site is a good place to find links to each of the online services. In particular, if you are interested in a trial for each service, you can visit the following pages: Office 365, CRM Online, Windows Intune, and Windows Azure. For Private Cloud technologies, start with some of the courses on Microsoft Virtual Academy and then download and install the Microsoft Private Cloud technologies including Windows Server 2008 R2 Hyper-V and System Center 2012 in your own environment and take it for a spin. Also, keep up to date with the Canadian IT Pro blog to learn about events Microsoft is delivering such as the IT Virtualization Boot Camps and more to get you started with these technologies hands on. Finally, I want to ask for your help to allow the team at Microsoft to continue to provide you what you need. Twice a year through something we call "The Global Relationship Study" – they reach out and contact you to see how they're doing and what Microsoft could do better. If you get an email from "Microsoft Feedback" with the subject line "Help Microsoft Focus on Customers and Partners" between March 5th and April 13th, please take a little time to tell them what you think. Cloud Computing Resources: Microsoft Server and Cloud Computing site – information on Microsoft's overall cloud strategy and products. Microsoft Virtual Academy – for free online training to help improve your IT skillset. Office 365 Trial/Info page – get more information or try it out for yourself. Office 365 Videos – see how businesses like yours have used Office 365 to transition to the cloud. Windows Intune Trial/Info – get more information or try it out for yourself. Microsoft Dynamics CRM Online page – information on trying and licensing Microsoft Dynamics CRM Online. Additional Resources You May Find Useful: Springboard Series Your destination for technical resources, free tools and expert guidance to ease the deployment and management of your Windows-based client infrastructure. TechNet Evaluation Center Try some of our latest Microsoft products for free, Like System Center 2012 Pre-Release Products, and evaluate them before you buy. AlignIT Manager Tech Talk Series A monthly streamed video series with a range of topics for both infrastructure and development managers. Ask questions and participate real-time or watch the on-demand recording. Tech·Days Online Discover what's next in technology and innovation with Tech·Days session recordings, hands-on labs and Tech·Days TV.

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• Why is x=x++ undefined?

  - by ugoren

  It's undefined because the it modifies x twice between sequence points. The standard says it's undefined, therefore it's undefined. That much I know. But why? My understanding is that forbidding this allows compilers to optimize better. This could have made sense when C was invented, but now seems like a weak argument. If we were to reinvent C today, would we do it this way, or can it be done better? Or maybe there's a deeper problem, that makes it hard to define consistent rules for such expressions, so it's best to forbid them? So suppose we were to reinvent C today. I'd like to suggest simple rules for expressions such as x=x++, which seem to me to work better than the existing rules. I'd like to get your opinion on the suggested rules compared to the existing ones, or other suggestions. Suggested Rules: Between sequence points, order of evaluation is unspecified. Side effects take place immediately. There's no undefined behavior involved. Expressions evaluate to this value or that, but surely won't format your hard disk (strangely, I've never seen an implementation where x=x++ formats the hard disk). Example Expressions x=x++ - Well defined, doesn't change x. First, x is incremented (immediately when x++ is evaluated), then it's old value is stored in x. x++ + ++x - Increments x twice, evaluates to 2*x+2. Though either side may be evaluated first, the result is either x + (x+2) (left side first) or (x+1) + (x+1) (right side first). x = x + (x=3) - Unspecified, x set to either x+3 or 6. If the right side is evaluated first, it's x+3. It's also possible that x=3 is evaluated first, so it's 3+3. In either case, the x=3 assignment happens immediately when x=3 is evaluated, so the value stored is overwritten by the other assignment. x+=(x=3) - Well defined, sets x to 6. You could argue that this is just shorthand for the expression above. But I'd say that += must be executed after x=3, and not in two parts (read x, evaluate x=3, add and store new value). What's the Advantage? Some comments raised this good point. It's not that I'm after the pleasure of using x=x++ in my code. It's a strange and misleading expression. What I want is to be able to understand complicated expressions. Normally, a complicated expression is no more than the sum of its parts. If you understand the parts and the operators combining them, you can understand the whole. C's current behavior seems to deviate from this principle. One assignment plus another assignment suddenly doesn't make two assignments. Today, when I look at x=x++, I can't say what it does. With my suggested rules, I can, by simply examining its components and their relations.

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• Using Recursive SQL and XML trick to PIVOT(OK, concat) a "Document Folder Structure Relationship" table, works like MySQL GROUP_CONCAT

  - by Kevin Shyr

  I'm in the process of building out a Data Warehouse and encountered this issue along the way.In the environment, there is a table that stores all the folders with the individual level.  For example, if a document is created here:{App Path}\Level 1\Level 2\Level 3\{document}, then the DocumentFolder table would look like this:IDID_ParentFolderName1NULLLevel 121Level 232Level 3To my understanding, the table was built so that:Each proposal can have multiple documents stored at various locationsDifferent users working on the proposal will have different access level to the folder; if one user is assigned access to a folder level, she/he can see all the sub folders and their content.Now we understand from an application point of view why this table was built this way.  But you can quickly see the pain this causes the report writer to show a document link on the report.  I wasn't surprised to find the report query had 5 self outer joins, which is at the mercy of nobody creating a document that is buried 6 levels deep, and not to mention the degradation in performance.With the help of 2 posts (at the end of this post), I was able to come up with this solution:Use recursive SQL to build out the folder pathUse SQL XML trick to concat the strings.Code (a reminder, I built this code in a stored procedure.  If you copy the syntax into a simple query window and execute, you'll get an incorrect syntax error) Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} -- Get all folders and group them by the original DocumentFolderID in PTSDocument table;WITH DocFoldersByDocFolderID(PTSDocumentFolderID_Original, PTSDocumentFolderID_Parent, sDocumentFolder, nLevel)AS (-- first member      SELECT 'PTSDocumentFolderID_Original' = d1.PTSDocumentFolderID            , PTSDocumentFolderID_Parent            , 'sDocumentFolder' = sName            , 'nLevel' = CONVERT(INT, 1000000)      FROM (SELECT DISTINCT PTSDocumentFolderID                  FROM dbo.PTSDocument_DY WITH(READPAST)            ) AS d1            INNER JOIN dbo.PTSDocumentFolder_DY AS df1 WITH(READPAST)                  ON d1.PTSDocumentFolderID = df1.PTSDocumentFolderID      UNION ALL      -- recursive      SELECT ddf1.PTSDocumentFolderID_Original            , df1.PTSDocumentFolderID_Parent            , 'sDocumentFolder' = df1.sName            , 'nLevel' = ddf1.nLevel - 1      FROM dbo.PTSDocumentFolder_DY AS df1 WITH(READPAST)            INNER JOIN DocFoldersByDocFolderID AS ddf1                  ON df1.PTSDocumentFolderID = ddf1.PTSDocumentFolderID_Parent)-- Flatten out folder path, DocFolderSingleByDocFolderID(PTSDocumentFolderID_Original, sDocumentFolder)AS (SELECT dfbdf.PTSDocumentFolderID_Original            , 'sDocumentFolder' = STUFF((SELECT '\' + sDocumentFolder                                         FROM DocFoldersByDocFolderID                                         WHERE (PTSDocumentFolderID_Original = dfbdf.PTSDocumentFolderID_Original)                                         ORDER BY PTSDocumentFolderID_Original, nLevel                                         FOR XML PATH ('')),1,1,'')      FROM DocFoldersByDocFolderID AS dfbdf      GROUP BY dfbdf.PTSDocumentFolderID_Original) And voila, I use the second CTE to join back to my original query (which is now a CTE for Source as we can now use MERGE to do INSERT and UPDATE at the same time).Each part of this solution would not solve the problem by itself because:If I don't use recursion, I cannot build out the path properly.  If I use the XML trick only, then I don't have the originating folder ID info that I need to link to the document.If I don't use the XML trick, then I don't have one row per document to show in the report.I could conceivably do this in the report function, but I'd rather not deal with the beginning or ending backslash and how to attach the document name.PIVOT doesn't do strings and UNPIVOT runs into the same problem as the above.I'm excited that each version of SQL server provides us new tools to solve old problems and/or enables us to solve problems in a more elegant wayThe 2 posts that helped me along:Recursive Queries Using Common Table ExpressionHow to use GROUP BY to concatenate strings in SQL server?

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• JEP 124: Enhance the Certificate Revocation-Checking API

  - by smullan

  Revocation checking is the mechanism to determine the revocation status of a certificate. If it is revoked, it is considered invalid and should not be used. Currently as of JDK 7, the PKIX implementation of java.security.cert.CertPathValidator  includes a revocation checking implementation that supports both OCSP and CRLs, the two main methods of checking revocation. However, there are very few options that allow you to configure the behavior. You can always implement your own revocation checker, but that's a lot of work. JEP 124 (Enhance the Certificate Revocation-Checking API) is one of the 11 new security features in JDK 8. This feature enhances the java.security.cert API to support various revocation settings such as best-effort checking, end-entity certificate checking, and mechanism-specific options and parameters. Let's describe each of these in more detail and show some examples. The features are provided through a new class named PKIXRevocationChecker. A PKIXRevocationChecker instance is returned by a PKIX CertPathValidator as follows: CertPathValidator cpv = CertPathValidator.getInstance("PKIX"); PKIXRevocationChecker prc = (PKIXRevocationChecker)cpv.getRevocationChecker(); You can now set various revocation options by calling different methods of the returned PKIXRevocationChecker object. For example, the best-effort option (called soft-fail) allows the revocation check to succeed if the status cannot be obtained due to a network connection failure or an overloaded server. It is enabled as follows: prc.setOptions(Enum.setOf(Option.SOFT_FAIL)); When the SOFT_FAIL option is specified, you can still obtain any exceptions that may have been thrown due to network issues. This can be useful if you want to log this information or treat it as a warning. You can obtain these exceptions by calling the getSoftFailExceptions method: List<CertPathValidatorException> exceptions = prc.getSoftFailExceptions(); Another new option called ONLY_END_ENTITY allows you to only check the revocation status of the end-entity certificate. This can improve performance, but you should be careful using this option, as the revocation status of CA certificates will not be checked. To set more than one option, simply specify them together, for example: prc.setOptions(Enum.setOf(Option.SOFT_FAIL, Option.ONLY_END_ENTITY)); By default, PKIXRevocationChecker will try to check the revocation status of a certificate using OCSP first, and then CRLs as a fallback. However, you can switch the order using the PREFER_CRLS option, or disable the fallback altogether using the NO_FALLBACK option. For example, here is how you would only use CRLs to check the revocation status: prc.setOptions(Enum.setOf(Option.PREFER_CRLS, Option.NO_FALLBACK)); There are also a number of other useful methods which allow you to specify various options such as the OCSP responder URI, the trusted OCSP responder certificate, and OCSP request extensions. However, one of the most useful features is the ability to specify a cached OCSP response with the setOCSPResponse method. This can be quite useful if the OCSPResponse has already been obtained, for example in a protocol that uses OCSP stapling. After you have set all of your preferred options, you must add the PKIXRevocationChecker to your PKIXParameters object as one of your custom CertPathCheckers before you validate the certificate chain, as follows: PKIXParameters params = new PKIXParameters(keystore); params.addCertPathChecker(prc); CertPathValidatorResult result = cpv.validate(path, params); Early access binaries of JDK 8 can be downloaded from http://jdk8.java.net/download.html

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• Cloud Adoption Challenges

  - by Herve Roggero

  Originally posted on: http://geekswithblogs.net/hroggero/archive/2013/11/07/cloud-adoption-challenges.aspxWhile cloud computing makes sense for most organizations and countless projects, I have seen customers significantly struggle with cloud adoption challenges. This blog post is not an attempt to provide a generic assessment of cloud adoption; rather it is an account of personal experiences in the field, some of which may or may not apply to your organization. Cloud First, Burst? In the rush to cloud adoption some companies have made the decision to redesign their core system with a cloud first approach. However a cloud first approach means that the system may not work anymore on-premises after it has been redesigned, specifically if the system depends on Platform as a Service (PaaS) components (such as Azure Tables). While PaaS makes sense when your company is in a position to adopt the cloud exclusively, it can be difficult to leverage with systems that need to work in different clouds or on-premises. As a result, some companies are starting to rethink their cloud strategy by designing for on-premises first, and modify only the necessary components to burst when needed in the cloud. This generally means that the components need to work equally well in any environment, which requires leveraging Infrastructure as a Service (IaaS) or additional investments for PaaS applications, or both.  What’s the Problem? Although most companies can benefit from cloud computing, not all of them can clearly identify a business reason for doing so other than in very generic terms. I heard many companies claim “it’s cheaper”, or “it allows us to scale”, without any specific metric or clear strategy behind the adoption decision. Other companies have a very clear strategy behind cloud adoption and can precisely articulate business benefits, such as “we have a 500% increase in traffic twice a year, so we need to burst in the cloud to avoid doubling our network and server capacity”. Understanding the problem being solved through by adopting cloud computing can significantly help organizations determine the optimum path and timeline to adoption. Performance or Scalability? I stopped counting the number of times I heard “the cloud doesn’t scale; our database runs faster on a laptop”.  While performance and scalability are related concepts, they are nonetheless different in nature. Performance is a measure of response time under a given load (meaning with a specific number of users), while scalability is the performance curve over various loads. For example one system could see great performance with 100 users, but timeout with 1,000 users, in which case the system wouldn’t scale. However another system could have average performance with 100 users, but display the exact same performance with 1,000,000 users, in which case the system would scale. Understanding that cloud computing does not usually provide high performance, but instead provides the tools necessary to build a scalable system (usually using PaaS services such as queuing and data federation), is fundamental to proper cloud adoption. Uptime? Last but not least, you may want to read the Service Level Agreement of your cloud provider in detail if you haven’t done so. If you are expecting 99.99% uptime annually you may be in for a surprise. Depending on the component being used, there may be no associated SLA at all! Other components may be restarted at any time, or services may experience failover conditions weekly ( or more) based on current overall conditions of the cloud service provider, most of which are outside of your control. As a result, for PaaS cloud environments (and to a certain extent some IaaS systems), applications need to assume failure and gracefully retry to be successful in the cloud in order to provide service continuity to end users. About Herve Roggero Herve Roggero, Windows Azure MVP, is the founder of Blue Syntax Consulting (http://www.bluesyntax.net). Herve's experience includes software development, architecture, database administration and senior management with both global corporations and startup companies. Herve holds multiple certifications, including an MCDBA, MCSE, MCSD. He also holds a Master's degree in Business Administration from Indiana University. Herve is the co-author of "PRO SQL Azure" and “PRO SQL Server 2012 Practices” from Apress, a PluralSight author, and runs the Azure Florida Association.

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• Use a custom value object or a Guid as an entity identifier in a distributed system?

  - by Kazark

  tl;dr I've been told that in domain-driven design, an identifier for an entity could be a custom value object, i.e. something other than Guid, string, int, etc. Can this really be advisable in a distributed system? Long version I will invent an situation analogous to the one I am currently facing. Say I have a distributed system in which a central concept is an egg. The system allows you to order eggs and see spending reports and inventory-centric data such as quantity on hand, usage, valuation and what have you. There area variety of services backing these behaviors. And say there is also another app which allows you to compose recipes that link to a particular egg type. Now egg type is broken down by the species—ostrich, goose, duck, chicken, quail. This is fine and dandy because it means that users don't end up with ostrich eggs when they wanted quail eggs and whatnot. However, we've been getting complaints because jumbo chicken eggs are not even close to equivalent to small ones. The price is different, and they really aren't substitutable in recipes. And here we thought we were doing users a favor by not overwhelming them with too many options. Currently each of the services (say, OrderSubmitter, EggTypeDefiner, SpendingReportsGenerator, InventoryTracker, RecipeCreator, RecipeTracker, or whatever) are identifying egg types with an industry-standard integer representation the species (let's call it speciesCode). We realize we've goofed up because this change could effect every service. There are two basic proposed solutions: Use a predefined identifier type like Guid as the eggTypeID throughout all the services, but make EggTypeDefiner the only service that knows that this maps to a speciesCode and eggSizeCode (and potentially to an isOrganic flag in the future, or whatever). Use an EggTypeID value object which is a combination of speciesCode and eggSizeCode in every service. I've proposed the first solution because I'm hoping it better encapsulates the definition of what an egg type is in the EggTypeDefiner and will be more resilient to changes, say if some people now want to differentiate eggs by whether or not they are "organic". The second solution is being suggested by some people who understand DDD better than I do in the hopes that less enrichment and lookup will be necessary that way, with the justification that in DDD using a value object as an ID is fine. Also, they are saying that EggTypeDefiner is not a domain and EggType is not an entity and as such should not have a Guid for an ID. However, I'm not sure the second solution is viable. This "value object" is going to have to be serialized into JSON and URLs for GET requests and used with a variety of technologies (C#, JavaScript...) which breaks encapsulation and thus removes any behavior of the identifier value object (is either of the fields optional? etc.) Is this a case where we want to avoid something that would normally be fine in DDD because we are trying to do DDD in a distributed fashion? Summary Can it be a good idea to use a custom value object as an identifier in a distributed system (solution #2)?

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• Application Logging needs work

  Application Logging Application logging is the act of logging events that occur within an application much like how a court report documents what happens in court case. Application logs can be useful for several reasons, but the most common use for logs is to recreate steps to find the root cause of applications errors. Other uses can include the detection of Fraud, verification of user activity, or provide audits on user/data interactions. “Logs can contain different kinds of data. The selection of the data used is normally affected by the motivation leading to the logging. “ (OWASP, 2009) OWASP also stats that logging include applicable debugging information like the event date time, responsible process, and a description of the event. “There are many reasons why a logging system is a necessary part of delivering a distributed application. One of the most important is the ability to track exactly how many users are using the application during different time periods.” (Hatton, 2000) Hatton also states that application logging helps system designers determine whether parts of an application aren't being used as designed. He implies that low usage can be used to identify if users like or do not like aspects of a system based on user usage of the application. This enables application designers to extract why users don't like aspects of an application so that changes can be made to increase its usefulness and effectiveness. “Logging memory usage can also assist you in tuning up the internals of your application. If you're experiencing a randomly occurring problem, being able to match activities performed with the memory status at the time may enable you to discover the cause of the problem. It also gives you a good indication of the health of the distributed server machine at the time any activity is performed. “ (Hatton, 2000) Commonly Logged Application Events (Defined by OWASP) Access of Data Creation of Data Modification of Data in any form Administrative Functions  Configuration Changes Debugging Information(Application Events)  Authorization Attempts  Data Deletion Network Communication  Authentication Events  Errors/Exceptions Application Error Logging The functionality associated with application error logging is actually the combination of proper error handling and applications logging.  If we look back at Figure 4 and Figure 5, these code examples allow developers to handle various types of errors that occur within the life cycle of an application’s execution. Application logging can be applied within the Catch section of the TryCatch statement allowing for the errors to be logged when they occur. By placing the logging within the Catch section specific error details can be accessed that help identify the source of the error, the path to the error, what caused the error and definition of the error that occurred. This can then be logged and reviewed at a later date in order recreate the error that was received based data found in the application log. By allowing applications to log errors developers IT staff can use them to recreate errors that are encountered by end-users or other dependent systems.

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• Auto-organized / smart inventory system?

  - by VeXe

  for the past week I've been working on an inventory system with Unity3D. At first I got help from the guys at Design3 but it wasn't too long till we split path, because I really didn't like the way they did their code, it didn't have any smell of OOP whatsoever. I took it further steps ahead - items take more than one slot, advanced placement system (items tries their best to find the best close fit), local mouse system (mouse gets trapped in active bag area), etc. Here's a demo of my work. What we would like to have in our game, is an auto-organizing feature - not auto-sort. We want this feature because our inventory's going to be in 'real-time' - not like in Resident Evil 1,2,3 etc where you would pause the game and do things in your inventory. Now imagine your self in a sticky situation surrounded by zombies, and you don't have bullets, you look around, you see that there are bullets nearby on the ground, so you go for them and try to pick them up, but they don't fit! you look at your inventory and find out that if you reorganize some of the items, it will fit! - now the player - in that situation doesn't have time to reorganize because he's surrounded with zombies and will die if he stops and organizes the inventory to make space (remember inventory in real-time, no pausing) - wouldn't it be nice for that to happen automatically? - Yes! (I believe this has been implemented in some games like Dungeon siege or something, so sure it's doable) take a look at this picture for example: Yes, so if you auto-sort the issue you will get your spaces but it's bad because: 1- Expensive: it doesn't need a whole sort operation to free those spaces, in the first picture, just slide the red item at the bottom to the very left, and you get the same spaces that you got from the auto-sort. 2- It's annoying to the player: "Who the F told you to re-order my stuff?" I'm not asking for "How to write the code" for this, I'm just asking for some guidance, where to look, what algorithms are involved? Is this something related to graphs and shortest path stuff? I hope not cuz I didn't manage to continue my college studies :/ But even if it is, just tell me and I will learn the stuff related. Notice there could be more than just one solution. So I guess the first thing I have to do is figure out if the situation is 'solvable' - if I know how to determine if a situation is solvable or not, then I can 'solve' it. I just need to know the conditions that makes it 'solvable'. And I believe there must be some algorithm/data structure for this. Here's a pic for more than one solution of trying to fit a 1x3 item: The arrows show just one of the solutions, but if you look you will find more than one. This is what I ultimately not auto-sorting but find a solution and applying it. Note that if I spend time on it I will come up with a way to solve it, but it wouldn't be the best way, it's like, holding a car wheel with your feet instead of your hands! XD Or just like trying to solve an issue that requires arrays, but you're not yet aware of their existence! So what is the right approach to this? Hope somebody helps, thanks a lot in advance :)

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• Optimal Data Structure for our own API

  - by vermiculus

  I'm in the early stages of writing an Emacs major mode for the Stack Exchange network; if you use Emacs regularly, this will benefit you in the end. In order to minimize the number of calls made to Stack Exchange's API (capped at 10000 per IP per day) and to just be a generally responsible citizen, I want to cache the information I receive from the network and store it in memory, waiting to be accessed again. I'm really stuck as to what data structure to store this information in. Obviously, it is going to be a list. However, as with any data structure, the choice must be determined by what data is being stored and what how it will be accessed. What, I would like to be able to store all of this information in a single symbol such as stack-api/cache. So, without further ado, stack-api/cache is a list of conses keyed by last update: `(<csite> <csite> <csite>) where <csite> would be (1362501715 . <site>) At this point, all we've done is define a simple association list. Of course, we must go deeper. Each <site> is a list of the API parameter (unique) followed by a list questions: `("codereview" <cquestion> <cquestion> <cquestion>) Each <cquestion> is, you guessed it, a cons of questions with their last update time: `(1362501715 <question>) (1362501720 . <question>) <question> is a cons of a question structure and a list of answers (again, consed with their last update time): `(<question-structure> <canswer> <canswer> <canswer> and ` `(1362501715 . <answer-structure>) This data structure is likely most accurately described as a tree, but I don't know if there's a better way to do this considering the language, Emacs Lisp (which isn't all that different from the Lisp you know and love at all). The explicit conses are likely unnecessary, but it helps my brain wrap around it better. I'm pretty sure a <csite>, for example, would just turn into (<epoch-time> <api-param> <cquestion> <cquestion> ...) Concerns: Does storing data in a potentially huge structure like this have any performance trade-offs for the system? I would like to avoid storing extraneous data, but I've done what I could and I don't think the dataset is that large in the first place (for normal use) since it's all just human-readable text in reasonable proportion. (I'm planning on culling old data using the times at the head of the list; each inherits its last-update time from its children and so-on down the tree. To what extent this cull should take place: I'm not sure.) Does storing data like this have any performance trade-offs for that which must use it? That is, will set and retrieve operations suffer from the size of the list? Do you have any other suggestions as to what a better structure might look like?

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• Custom Text and Binary Payloads using WebSocket (TOTD #186)

  - by arungupta

  TOTD #185 explained how to process text and binary payloads in a WebSocket endpoint. In summary, a text payload may be received as public void receiveTextMessage(String message) {    . . . } And binary payload may be received as: public void recieveBinaryMessage(ByteBuffer message) {    . . .} As you realize, both of these methods receive the text and binary data in raw format. However you may like to receive and send the data using a POJO. This marshaling and unmarshaling can be done in the method implementation but JSR 356 API provides a cleaner way. For encoding and decoding text payload into POJO, Decoder.Text (for inbound payload) and Encoder.Text (for outbound payload) interfaces need to be implemented. A sample implementation below shows how text payload consisting of JSON structures can be encoded and decoded. public class MyMessage implements Decoder.Text<MyMessage>, Encoder.Text<MyMessage> {     private JsonObject jsonObject;    @Override    public MyMessage decode(String string) throws DecodeException {        this.jsonObject = new JsonReader(new StringReader(string)).readObject();               return this;    }     @Override    public boolean willDecode(String string) {        return true;    }     @Override    public String encode(MyMessage myMessage) throws EncodeException {        return myMessage.jsonObject.toString();    } public JsonObject getObject() { return jsonObject; }} In this implementation, the decode method decodes incoming text payload to MyMessage, the encode method encodes MyMessage for the outgoing text payload, and the willDecode method returns true or false if the message can be decoded. The encoder and decoder implementation classes need to be specified in the WebSocket endpoint as: @WebSocketEndpoint(value="/endpoint", encoders={MyMessage.class}, decoders={MyMessage.class}) public class MyEndpoint { public MyMessage receiveMessage(MyMessage message) { . . . } } Notice the updated method signature where the application is working with MyMessage instead of the raw string. Note that the encoder and decoder implementations just illustrate the point and provide no validation or exception handling. Similarly Encooder.Binary and Decoder.Binary interfaces need to be implemented for encoding and decoding binary payload. Here are some references for you: JSR 356: Java API for WebSocket - Specification (Early Draft) and Implementation (already integrated in GlassFish 4 promoted builds) TOTD #183 - Getting Started with WebSocket in GlassFish TOTD #184 - Logging WebSocket Frames using Chrome Developer Tools, Net-internals and Wireshark TOTD #185: Processing Text and Binary (Blob, ArrayBuffer, ArrayBufferView) Payload in WebSocket Subsequent blogs will discuss the following topics (not necessary in that order) ... Error handling Interface-driven WebSocket endpoint Java client API Client and Server configuration Security Subprotocols Extensions Other topics from the API

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• How to handle multi-processing of libraries which already spawn sub-processes?

  - by exhuma

  I am having some trouble coming up with a good solution to limit sub-processes in a script which uses a multi-processed library and the script itself is also multi-processed. Both, the library and script are modifiable by us. I believe the question is more about design than actual code, but for what it's worth, it's written in Python. The goal of the library is to hide implementation details of various internet routers. For that reason, the library has a "Proxy" factory method which takes the IP of a router as parameter. The factory then probes the device using a set of possible proxies. Usually, there is one proxy which immediately knows that is is able to send commands to this device. All others usually take some time to return (given a timeout). One thought was already to simply query the device for an identifier, and then select the proper proxy using that, but in order to do so, you would already need to know how to query the device. Abstracting this knowledge is one of the main purposes of the library, so that becomes a little bit of a "circular-requirement"/deadlock: To connect to a device, you need to know what proxy to use, and to know what proxy to create, you need to connect to a device. So probing the device is - as we can see - the best solution so far, apart from keeping a lookup-table somewhere. The library currently kills all remaining processes once a valid proxy has been found. And yes, there is always only one good proxy per device. Currently there are about 12 proxies. So if one create a proxy instance using the factory, 12 sub-processes are spawned. So far, this has been really useful and worked very well. But recently someone else wanted to use this library to "broadcast" a command to all devices. So he took the library, and wrote his own multi-processed script. This obviously spawned 12 * n processes where n is the number of IPs to which he broadcasted. This has given us two problems: The host on which the command was executed slowed down to a near halt. Aborting the script with CTRL+C ground the system to a total halt. Not even the hardware console responded anymore! This may be due to some Python strangeness which still needs to be investigated. Maybe related to http://bugs.python.org/issue8296 The big underlying question, is how to design a library which does multi-processing, so other applications which use this library and want to be multi-processed themselves do not run into system limitations. My first thought was to require a pool to be passed to the library, and execute all tasks in that pool. In that way, the person using the library has control over the usage of system resources. But my gut tells me that there must be a better solution. Disclaimer: My experience with multiprocessing is fairly limited. I have implemented a few straightforward which did not require access control to resources. So I have not yet any practical experience with semaphores or mutexes. p.s.: In the future, we may have enough information to do this without the probing. But the database which would contain the proper information is not yet operational. Also, the design about multiprocessing a multiprocessed library intrigues me :)

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• Pinterest and the Rising Power of Imagery

  - by Mike Stiles

  If images keep you glued to a screen, you’re hardly alone. Countless social users are letting their eyes do the walking, waiting for that special photo to grab their attention. And perhaps more than any other social network, Pinterest has been giving those eyes plenty of room to walk. Pinterest came along in 2010. Its play was that users could simply create topic boards and pin pictures to the appropriate boards for sharing. Yes there are some words, captions mostly, but not many. The speed of its growth raised eyebrows. Traffic quadrupled in the last quarter of 2011, with 7.51 million unique visitors in December alone. It now gets 1.9 billion monthly page views. And it was sticky. In the US, the average time a user spends strolling through boards and photos on Pinterest is 15 minutes, 50 seconds. Proving the concept of browsing a catalogue is not dead, it became a top 5 referrer for several apparel retailers like Land’s End, Nordstrom, and Bergdorfs. Now a survey of online shoppers by BizRate Insights says that Pinterest is responsible for more purchases online than Facebook. Over 70% of its users are going there specifically to keep up with trends and get shopping ideas. And when they buy, the average order value is $179. Pinterest is also scoring better in terms of user engagement. 66% of pinners regularly follow and repin retailers, whereas 17% of Facebook fans turn to that platform for purchase ideas. (Facebook still wins when it comes to reach and driving traffic to 3rd-party sites by the way). Social posting best practices have consistently shown that posts with photos are rewarded with higher engagement levels. You may be downright Shakespearean in your writing, but what makes images in the digital world so much more powerful than prose? 1. They transcend language barriers. 2. They’re fun and addictive to look at. 3. They can be consumed in fractions of a second, important considering how fast users move through their social content (admit it, you do too). 4. They’re efficient gateways. A good picture might get them to the headline. A good headline might then get them to the written content. 5. The audience for them surpasses demographic limitations. 6. They can effectively communicate and trigger an emotion. 7. With mobile use soaring, photos are created on those devices and easily consumed and shared on them. Pinterest’s iPad app hit #1 in the Apple store in 1 day. Even as far back as 2009, over 2.5 billion devices with cameras were on the streets generating in just 1 year, 10% of the number of photos taken…ever. But let’s say you’re not a retailer. What if you’re a B2B whose products or services aren’t visual? Should you worry about your presence on Pinterest? As with all things, you need a keen awareness of who your audience is, where they reside online, and what they want to do there. If it doesn’t make sense to put a tent stake in Pinterest, fine. But ignore the power of pictures at your own peril. If not visually, how are you going to attention-grab social users scrolling down their News Feeds at top speed? You’re competing with every other cool image out there from countless content sources. Bore us and we’ll fly right past you.

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• Data Mining Email with Thunderbird

  - by user554629

  Oracle has many formal, searchable locations:  Service Requests, BugIDs, Technical Documents. These contain the results of an investigation for a customer crash situation;  they're created after the intense work of resolution is over, and typically contain the "root cause" of the failure ... but not the methods for identifying that cause. Email is still the standby for interacting with quickly formed groups of specialists, focusing on a particular incident.Customer BI, Network and System specialists;  Oracle Tech Support, Development, Consultants; OEM Database, OS technical support.   It is a chaotic, time-oriented set of configuration, call stacks, changes, techniques to discover and repair the failure. I needed to organize that information into something cohesive to prepare the blog entry on Teradata.  My corporate email client of choice is Thunderbird.   My original (flawed) search technique: R-Click on Inbox in Thunderbird left pane, and choose Search Messages Subject:  [ teradata ] Results: A new window titled "Search Messages"Single pane of selected messagesColumn headings:  Subject  From  Date  LocationNo preview window for messages There are 673 email entries in the result ( too many )  R-click icon just above the vertical scroll bar on the rightCheck [x] Tags Click on the Tags header to sort by "Important" View contents of message by double-clickingOpens in the Thunderbird Main Window in a new Tab Not what I was looking for, close the tab and try again. There has to be a better way.  ( and there is ) I need to be more productive, eliminating duplicate-chained messages, for example.   Even the Tag "Important" that was added during the investigation phase, is "not so much" for my current task. In the "Search Messages" window, click [ Save as Search Folder ] [ teradata ]  Appears as a new folder in my Inbox. Focus on that folder and the results appear with a list of messages like every other folder in the Inbox.Only the results of the search are shown A preview window is now available for each message Sort, Select message, Cursor Down ... navigates quickly through the messages. But wait, there's more ... Click Find ( Ctrl-F) Enter a search term for the message body, like.[ LIBPATH ] The search is "sticky" ... each message you cycle through wil focus ( and highlight) the LIBPATH search term. And still more .... Reset the Tag"Important" message.   Press "1" and the tag is removed Press "4" and a new Tag "ToDo" is applied After applying all of the tags, sort by Tag for a new message order Adjust the search criteria ... R-click on the [ teradata ] search folder, and choose Properties Add additional criteria to narrow the search Some of the information I'm looking for did not contain "teradata" in the subject line. + Body  [ contains ] [ Best Practices ] That's it.  Much more efficient search.   Thank you Thunderbird.

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• DirectX particle system. ConstantBuffer

  - by Liuka

  I'm new in DirectX and I'm making a 2D game. I want to use a particle system to simulate a 3D starfield, so each star has to set its own constant buffer for the vertexshader es. to set it's world matrix. So if i have 500 stars (that move every frame) i need to call 500 times VSsetconstantbuffer, and map/unmap each buffer. with 500 stars i have an average of 220 fps and that's quite good. My bottelneck is Vs/PsSetconstantbuffer. If i dont call this function i have 400 fps(obliviously nothing is display, since i dont set the position of the stars). So is there a method to speed up the render of the particle system?? Ps. I'm using intel integrate graphic (hd 2000-3000). with a nvidia (or amd) gpu will i have the same bottleneck?? If, for example, i dont call setshaderresource i have 10-20 fps more (for 500 objcets), that is not 180.Why does SetConstantBuffer take so long?? LPVOID VSdataPtr = VSmappedResource.pData; memcpy(VSdataPtr, VSdata, CszVSdata); context->Unmap(VertexBuffer, 0); result = context->Map(PixelBuffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &PSmappedResource); if (FAILED(result)) { outputResult.OutputErrorMessage(TITLE, L"Cannot map the PixelBuffer", &result, OUTPUT_ERROR_FILE); return; } LPVOID PSdataPtr = PSmappedResource.pData; memcpy(PSdataPtr, PSdata, CszPSdata); context->Unmap(PixelBuffer, 0); context->VSSetConstantBuffers(0, 1, &VertexBuffer); context->PSSetConstantBuffers(0, 1, &PixelBuffer); this update and set the buffer. It's part of the render method of a sprite class that contains a the vertex buffer and the texture to apply to the quads(it's a 2d game) too. I have an array of 500 stars (sprite setup with a star texture). Every frame: clear back buffer; draw the array of stars; present the backbuffer; draw also call the function update( which calculate the position of the sprite on screen based on a "camera class") Ok, create a vertex buffer with the vertices of each quads(stars) seems to be good, since the stars don't change their "virtual" position; so.... In a particle system (where particles move) it's better to have all the object in only one vertices array, rather then an array of different sprite/object in order to update all the vertices' position with a single setbuffer call. In this case i have to use a dynamic vertex buffer with the vertices positions like this: verticesForQuad={{ XMFLOAT3((float)halfDImensions.x-1+pos.x, (float)halfDImensions.y-1+pos.y, 1.0f), XMFLOAT2(1.0f, 0.0f) }, { XMFLOAT3((float)halfDImensions.x-1+pos.x, -(float)halfDImensions.y-1+pos.y, 1.0f), XMFLOAT2(1.0f, 1.0f) }, { XMFLOAT3(-(float)halfDImensions.x-1+pos.x, (float)halfDImensions.y-1.pos.y, 1.0f), XMFLOAT2(0.0f, 0.0f) }, { XMFLOAT3(-(float)halfDImensions.x-1.pos.x, -(float)halfDImensions.y-1+pos.y, 1.0f), XMFLOAT2(0.0f, 1.0f) }, ....other quads} where halfDimensions is the halfsize in pixel of a texture and pos the virtual position of a star. than create an array of verticesForQuad and create the vertex buffer ZeroMemory(&vertexDesc, sizeof(vertexDesc)); vertexDesc.Usage = D3D11_USAGE_DEFAULT; vertexDesc.BindFlags = D3D11_BIND_VERTEX_BUFFER; vertexDesc.ByteWidth = sizeof(VertexType)* 4*numStars; ZeroMemory(&resourceData, sizeof(resourceData)); resourceData.pSysMem = verticesForQuad; result = device->CreateBuffer(&vertexDesc, &resourceData, &CvertexBuffer); and call each frame Context->IASetVertexBuffers(0, 1, &CvertexBuffer, &stride, &offset); But if i want to add and remove obj i have to recreate the buffer each time, havent i?? There is a faster way? I think i can create a vertex buffer with a max size (es. 10000 objs) and when i update it set only the 250 position (for 250 onjs for example) and pass this number as the vertexCount to the draw function (numObjs*4), or i'm worng

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• Is this over-abstraction? (And is there a name for it?)

  - by mwhite

  I work on a large Django application that uses CouchDB as a database and couchdbkit for mapping CouchDB documents to objects in Python, similar to Django's default ORM. It has dozens of model classes and a hundred or two CouchDB views. The application allows users to register a "domain", which gives them a unique URL containing the domain name that gives them access to a project whose data has no overlap with the data of other domains. Each document that is part of a domain has its domain property set to that domain's name. As far as relationships between the documents go, all domains are effectively mutually exclusive subsets of the data, except for a few edge cases (some users can be members of more than one domain, and there are some administrative reports that include all domains, etc.). The code is full of explicit references to the domain name, and I'm wondering if it would be worth the added complexity to abstract this out. I'd also like to know if there's a name for the sort of bound property approach I'm taking here. Basically, I have something like this in mind: Before in models.py class User(Document): domain = StringProperty() class Group(Document): domain = StringProperty() name = StringProperty() user_ids = StringListProperty() # method that returns related document set def users(self): return [User.get(id) for id in self.user_ids] # method that queries a couch view optimized for a specific lookup @classmethod def by_name(cls, domain, name): # the view method is provided by couchdbkit and handles # wrapping json CouchDB results as Python objects, and # can take various parameters modifying behavior return cls.view('groups/by_name', key=[domain, name]) # method that creates a related document def get_new_user(self): user = User(domain=self.domain) user.save() self.user_ids.append(user._id) return user in views.py: from models import User, Group # there are tons of views like this, (request, domain, ...) def create_new_user_in_group(request, domain, group_name): group = Group.by_name(domain, group_name)[0] user = User(domain=domain) user.save() group.user_ids.append(user._id) group.save() in group/by_name/map.js: function (doc) { if (doc.doc_type == "Group") { emit([doc.domain, doc.name], null); } } After models.py class DomainDocument(Document): domain = StringProperty() @classmethod def domain_view(cls, *args, **kwargs): kwargs['key'] = [cls.domain.default] + kwargs['key'] return super(DomainDocument, cls).view(*args, **kwargs) @classmethod def get(cls, *args, **kwargs, validate_domain=True): ret = super(DomainDocument, cls).get(*args, **kwargs) if validate_domain and ret.domain != cls.domain.default: raise Exception() return ret def models(self): # a mapping of all models in the application. accessing one returns the equivalent of class BoundUser(User): domain = StringProperty(default=self.domain) class User(DomainDocument): pass class Group(DomainDocument): name = StringProperty() user_ids = StringListProperty() def users(self): return [self.models.User.get(id) for id in self.user_ids] @classmethod def by_name(cls, name): return cls.domain_view('groups/by_name', key=[name]) def get_new_user(self): user = self.models.User() user.save() views.py @domain_view # decorator that sets request.models to the same sort of object that is returned by DomainDocument.models and removes the domain argument from the URL router def create_new_user_in_group(request, group_name): group = request.models.Group.by_name(group_name) user = request.models.User() user.save() group.user_ids.append(user._id) group.save() (Might be better to leave the abstraction leaky here in order to avoid having to deal with a couchapp-style //! include of a wrapper for emit that prepends doc.domain to the key or some other similar solution.) function (doc) { if (doc.doc_type == "Group") { emit([doc.name], null); } } Pros and Cons So what are the pros and cons of this? Pros: DRYer prevents you from creating related documents but forgetting to set the domain. prevents you from accidentally writing a django view - couch view execution path that leads to a security breach doesn't prevent you from accessing underlying self.domain and normal Document.view() method potentially gets rid of the need for a lot of sanity checks verifying whether two documents whose domains we expect to be equal are. Cons: adds some complexity hides what's really happening requires no model modules to have classes with the same name, or you would need to add sub-attributes to self.models for modules. However, requiring project-wide unique class names for models should actually be fine because they correspond to the doc_type property couchdbkit uses to decide which class to instantiate them as, which should be unique. removes explicit dependency documentation (from group.models import Group)

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• Upgrade to Xubuntu 13.10 - Saucy Salamander

  As a common 'fashion' it is possible to upgrade an existing installation of Ubuntu or one of its derivates every six months. Of course, you might opt-in for the adventure and directly keep your system always on the latest version (including alphas and betas), or you might like to play safe and stay on the long-term support (LTS) versions which are updated every two years only. As for me, I'd like to jump from release to release on my main desktop machine. And since 17th October Saucy Salamander or also known as Ubuntu 13.10 has been released for general use. The following paragraphs document the steps I went in order to upgrade my system to the recent version. Don't worry about the fact that I'm actually using Xubuntu. It's mainly a flavoured version of Ubuntu running Xfce 4.10 as default X Window manager. Well, I have Gnome and LXDE on the same system... just out of couriosity. Preparing the system Before you think about upgrading you have to ensure that your current system is running on the latest packages. This can be done easily via a terminal like so: $ sudo apt-get update && sudo apt-get -y dist-upgrade --fix-missing Next, we are going to initiate the upgrade itself: $ sudo update-manager As a result the graphical Software Updater should inform you that a newer version of Ubuntu is available for installation. Ubuntu's Software Updater informs you whether an upgrade is available Running the upgrade After clicking 'Upgrade...' you will be presented with information about the new version. Details about Ubuntu 13.10 (Saucy Salamander) Simply continue with the procedure and your system will be analysed for the next steps. Analysing the existing system and preparing the actual upgrade to 13.10 Next, we are at the point of no return. Last confirmation dialog before having a coffee break while your machine is occupied to download the necessary packages. Not the best bandwidth at hand after all... yours might be faster. Are you really sure that you want to start the upgrade? Let's go and have fun! Anyway, bye bye Raring Ringtail and Welcome Saucy Salamander! In case that you added any additional repositories like Medibuntu or PPAs you will be informed that they are going to be disabled during the upgrade and they might require some manual intervention after completion. Ubuntu is playing safe and third party repositories are disabled during the upgrade Well, depending on your internet bandwidth this might take something between a couple of minutes and some hours to download all the packages and then trigger the actual installation process. In my case I left my PC unattended during the night. Time to reboot Finally, it's time to restart your system and see what's going to happen... In my case absolutely nothing unexpected. The system booted the new kernel 3.11.0 as usual and I was greeted by a new login screen. Honestly, 'same' system as before - which is good and I love that fact of consistency - and I can continue to work productively. And also Software Updater confirms that we just had a painless upgrade: System is running Ubuntu 13.10 - Saucy Salamander - and up to date See you in six months again... ;-) Post-scriptum In case that you would to upgrade to the latest development version of Ubuntu, run the following command in a console: $ sudo update-manager -d And repeat all steps as described above.

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• Multidimensional multiple-choice knapsack problem: find a feasible solution

  - by Onheiron

  My assignment is to use local search heuristics to solve the Multidimensional multiple-choice knapsack problem, but to do so I first need to find a feasible solution to start with. Here is an example problem with what I tried so far. Problem R1 R2 R3 RESOUCES : 8 8 8 GROUPS: G1: 11.0 3 2 2 12.0 1 1 3 G2: 20.0 1 1 3 5.0 2 3 2 G3: 10.0 2 2 3 30.0 1 1 3 Sorting strategies To find a starting feasible solution for my local search I decided to ignore maximization of gains and just try to fit the resources requirements. I decided to sort the choices (strategies) in each group by comparing their "distance" from the multidimensional space origin, thus calculating SQRT(R1^2 + R2^2 + ... + RN^2). I felt like this was a keen solution as it somehow privileged those choices with resouce usages closer to each other (e.g. R1:2 R2:2 R3:2 < R1:1 R2:2 R3:3) even if the total sum is the same. Doing so and selecting the best choice from each group proved sufficent to find a feasible solution for many[30] different benchmark problems, but of course I knew it was just luck. So I came up with the problem presented above which sorts like this: R1 R2 R3 RESOUCES : 8 8 8 GROUPS: G1: 12.0 1 1 3 < select this 11.0 3 2 2 G2: 20.0 1 1 3 < select this 5.0 2 3 2 G3: 30.0 1 1 3 < select this 10.0 2 2 3 And it is not feasible because the resources consmption is R1:3, R2:3, R3:9. The easy solution is to pick one of the second best choices in group 1 or 2, so I'll need some kind of iteration (local search[?]) to find the starting feasible solution for my local search solution. Here are the options I came up with Option 1: iterate choices I tried to find a way to iterate all the choices with a specific order, something like G1 G2 G3 1 1 1 2 1 1 1 2 1 1 1 2 2 2 1 ... believeng that feasible solutions won't be that far away from the unfeasible one I start with and thus the number of iterations will keep quite low. Does this make any sense? If yes, how can I iterate the choices (grouped combinations) of each group keeping "as near as possibile" to the previous iteration? Option 2: Change the comparation term I tried to think how to find a better variable to sort the choices on. I thought at a measure of how "precious" a resource is based on supply and demand, so that an higer demand of a more precious resource will push you down the list, but this didn't help at all. Also I thought there probably isn't gonna be such a comparsion variable which assures me a feasible solution at first strike. I there such a variable? If not, is there a better sorting criteria anyways? Option 3: implement any known sub-optimal fast solving algorithm Unfortunately I could not find any of such algorithms online. Any suggestion?

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• Understanding the Value of SOA

  - by Mala Narasimharajan

  Written By: Debra Lilley, ACE Director, Fusion Applications Again I want to talk from my area of expertise of Fusion Applications and talk about their design fundamentals. If you look at the table below and start at the bottom Oracle have defined all of the business objects e.g. accounts, people, customers, invoices etc. used by Fusion Applications; each of these objects contain all of the information required and can be expanded if necessary.  That Oracle have created for each of these business objects every action that is needed for the applications e.g. all the actions to create a new customer, checking to see if it exists, credit checking with D&B (Dun & Bradstreet < http://www.dnb.co.uk/> ) , creating the record, notifying those required etc. Each of these actions is a stand-alone web service. Again you can create a new actions or subscribe to an external provided web service e.g. the D&B check. The diagram also shows that all of development of Fusion Applications is from their Fusion Middleware offerings. Then the Intelligent Business Process is the order in which you run these actions, this is Service Orientated Architecture, SOA. Not only is SOA used to orchestrate actions within Fusion Applications it is also used in the integration of Fusion Applications with the rest of the Oracle stable of applications such as EBS, PeopleSoft, JDE and Siebel. The other applications are written with propriety development tools so how do they work with SOA? It’s a very simple answer, with the introduction of the Oracle SOA platform each process within these applications was made available to be called as a web service. I won’t go into technically how that is done but what’s known as a wrapper to allow each of them to act in this way was added. Finally at the top of the diagram are the questions that each Fusion Application process must answer, and this is the ‘special’ sauce that makes them so good, the User Experience, but that is a topic for another day, or you can read about it in my blog http://debrasoracle.blogspot.co.uk/2014/04/going-on-record-about-fusion-apps-cloud.html or Oracle’s own UX blog https://blogs.oracle.com/usableapps/ The concept behind AppAdvantage is not new the idea that Oracle technology can add value to your Oracle applications investments is pretty fundamental. Nishit Rao who is in AppAdvantage team provided myself and other ACE Directors with demo kits so that we could demonstrate SOA running with the applications. The example I learnt to build was that of the EBS inventory open interface. The simple concept is that request records can be added to a table and an import run that creates these as transactions in inventory. What’s SOA allows you to do is to add to the table from any source and then run this process automatically whereas traditionally you had to run the process at regular intervals because you didn’t know if the table was empty or not. This may just sound like a different way of doing the same thing but if the process is critical for your business then the interval was very small and the process run potentially many times unnecessarily. Using SOA it only happened when necessary without any delay. So in my post today I’ve talked about how SOA is used with Fusion Applications and in the linking with more traditional applications but that is only the tip of the iceberg of potential, your applications are just part of your IT systems and SOA can orchestrate your data across all of them; the beauty of open standards.  Debra Lilley, Fusion Champion, UKOUG Board Member, Fusion User Experience Advocate and ACE Director.  Lilley has 18 years experience with Oracle Applications, with E Business Suite since 9.4.1, moving to Business Intelligence Team Lead and Oracle Alliance Director. She has spoken at over 100 conferences worldwide and posts at debrasoraclethoughts

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