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• REL ME tag - trying to figure it out

  - by nekdo

  Regarding http://support.google.com/webmasters/bin/answer.py?hl=en&answer=1229920 to scrolled down section ''Examples'' to the point ''1.'' to the second code line which is: <a rel="me" href="https://plus.google.com/105240469625818678725/"> <img src="//www.google.com/images/icons/ui/gprofile_button-16.png"></a> On the page says that I have to add this line to the Contact Me page of own website in order to get Google Profile button. Exact code which one should be copy and pasted I am able to get here: http://www.google.com/webmasters/profilebutton/ Questions: 1). As you can see on the second URL, to make Google Profile button I need to use "author" tag and not "me" tag. But the first URL which I showed (the line in this message above) shows that I have to use "me" tag and even without this: width="32" height="32". I am already aware that I have to type (second URL) my own Google Profile URL. So do I just MANUALLY ( ! ) change this: <a rel="author" href="https://profiles.google.com/109412257237874861202"> <img src="http://www.google.com/images/icons/ui/gprofile_button-32.png" width="32" height="32"></a> to this (note: two changes done): <a rel="me" href="https://profiles.google.com/109412257237874861202"> <img src="http://www.google.com/images/icons/ui/gprofile_button-32.png"></a> Is this correct? I assume that plus.google.com is the same as profiles.google.com (both is URL of Google Profile). 2). If I was wrong with my first question then the second answer probably won't be even useful but still: Where exactly should I paste the code: <a rel="me" href="https://profiles.google.com/109412257237874861202"> <img src="http://www.google.com/images/icons/ui/gprofile_button-32.png"></a> inside Author Page of own website? I think it doesn't matter where. Also: will this icon be for sure enough or do I also have to make such anchor text with rel me in a ''shape'' of text (for word sentence such as ''Look At My Google Profile'')? Or is just icon really enough? 3). In the same section (''1.'') of the same page (link [first one] provided above) it says that I need to use first author tag to link to Author/Contact Me page of own website in order to later use Me tag. But I think in the explanation is little mistake. Shouldn't be instead of: <a rel="author" href="http://www.cnet.com/profile/iamjaygreene/">Jay Greene</a> this: <a rel="author" href="http://www.cnet.com/profile/iamjaygreene.html">Jay Greene</a> ?

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• 2D water with dynamic waves

  - by user1103457

  New Super Mario Bros has really cool 2D water that I'd like to learn how to create. Here's a video showing it. When something hits the water, it creates a wave. There are also constant "background" waves. You can get a good look at the constant waves just after 00:50 when the camera isn't moving. I assume the splashes in NSMB work as in the first part of this tutorial. But in NSMB the water also has constant waves on the surface, and the splashes look very different. Another difference is that in the tutorial, if you create a splash, it first creates a deep "hole" in the water at the origin of the splash. In new super mario bros this hole is absent or much smaller. I am referring to the splashes that the player creates when jumping in and out of the water. How do they create the constant waves and the splashes? I am especially interested in the splashes, and how they work together with the constant waves. I am programming in XNA. I've tried this myself, but couldn't really get it all to work well together. Bonus questions: How do they create the light spots just under the surface of the waves and how do they texture the deeper parts of the water? This is the first time I try to create water like this. EDIT: I assume the constant waves are created using a sine function. The splashes are probably created in a way like in the tutorial. (But they are not the same, so I am still interested in how to make this kind of splashes) But I have a lot of trouble combining those things. I know I can use the sine function to set the height of a specific watercolumn but the splashes are using the speed, to determine the new height. I can't figure out how to combine those. Not that I am not asking how the developers of new super mario bros did this exactly. I am just interested in ways to recreate an effect like it. This week I have an examweek so I don't have time to work on the code. After this week I will spend a lot of time on it. But I am constantly thinking about it, so that's why I will be checking comments etc. I just won't be looking at the code since it might be too time-consuming.

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• Survey results: Open source developer preferences

  We recently conducted a survey of open source developers to learn about their current preferences around hosting sites and source control systems.  The survey was primarily advertised via Twitter, and we tried to avoid pushing the survey among audiences that would be specifically oriented towards a particular site (for example we did not advertise the survey from the CodePlex twitter account). In total there were just under 500 responses, so a reasonable sample size although not necessarily enough to guarantee fully representative results.  One of the survey questions was what is your preferred operating system for development, and looking at the results they are particularly interesting when split by operating system preference because of how significant the difference is:   Table 1 - Preferences by what is preferred operating system for development   As you can see, the preferences among developers which prefer Windows is very different from Linux and Mac oriented developers.  Again, the question was on what operating system they prefer to use for development, and didn’t ask what type of applications they create, so presumably many create things like websites which are cross-platform from a user perspective regardless of the operating system they prefer developing with. For hosting site preference, CodePlex and GitHub are roughly tied for first place among Windows developers and combined are preferred by over 75%.  However with Linux and Mac developers, GitHub has a runaway lead over the other sites.  Perhaps not particularly surprising, CodePlex has negligible mindshare among Linux and Mac developers.  It is somewhat surprising how low SourceForge and Google Code are given historically they used to rank much higher. Looking at version control preferences is also interesting.  Among Windows developers TFS, Mercurial, Subversion, and Git all have a sizable following.  While for Linux and Mac developers it is almost all Git and Mercurial, with Git having a substantial lead.  Git is generally considered to run better on Linux and have more of a Unix feel, so not really surprising to see it more popular there compared to Windows developers.  It is surprising how low Subversion has dropped since it was the dominant preference not long ago for open source developers.  Around a quarter of Windows developers still prefer Subversion, but Linux and Mac developers have largely abandoned it.  The trend towards distributed version control systems (e.g. Mercurial and Git) is strong, with over 50% of Windows developers now prefer DVCS, and over 80% of Linux and Mac developers.

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• Playing with F#

  - by mroberts

  Project Euler is a awesome site.   When working with a new language it can be tricky to find problems that need solving, that are more complex than "Hello World" and simpler than a full blown application. Project Euler gives use just that, cool and thought provoking problems that usually don't take days to solve.  I've solved a number of questions with C# and some with Java.  BTW, I used Java because it had BigInteger support before .Net. A couple weeks ago, back when winter had a firm grip on Columbus, OH, I began playing (researching) with F#.  I began with Problem #1 from Project Euler.  I started by looking at my solution in C#. Here is my solution in C#. 1: using System; 2: using System.Collections.Generic; 3:   4: namespace Problem001 5: { 6: class Program 7: { 8: static void Main(string[] args) 9: { 10: List<int> values = new List<int>(); 11:   12: for (int i = 1; i < 1000; i++) 13: { 14: if (i % 3 == 0 || i % 5 == 0) 15: values.Add(i); 16: } 17: int total = 0; 18:   19: values.ForEach(v => total += v); 20:   21: Console.WriteLine(total); 22: Console.ReadKey(); 23: } 24: } 25: }   Now, after much tweaking and learning, here is my solution in F#.   1: open System 2:   3: let calc n = 4: [1..n] 5: |> List.map (fun x -> if (x % 3 = 0 || x % 5 = 0) then x else 0) 6: |> List.sum 7:   8: let main() = 9: calc 999 10: |> printfn "result = %d" 11: Console.ReadKey(true) |> ignore 12:   13: main() Just this little example highlights some cool things about F#. Type inference. F# infers the type of a value.  In the C# code above we declare a number of variables, the list, and a couple ints.  F# does not require this, it infers the calc (a function) accepts a int and returns a int. Great built in functionality for Lists.  List.map for example. BTW, I don’t think I’m spilling the beans by giving away the code for Problem 1.  It by far is the easiest question, IMHO, solved by 92,000+ people. Next I’ll look into writing a class library with F#.

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• Ubuntu 12.04.3 Graphics Issues: Broken Pipes, Reinstalled Xorg and Bumblebee

  - by user190488

  It seems I have a problem, and am only making it worse by following what I find online. I have a new Asus N550JV-D71 (not sure about the part after the dash, though I definitely know it includes 71). I decided to downgrade Windows 8 to 7, then dual boot Ubuntu 12.04 with it (there were issues with Windows 8, and I had a Windows 7 disk handy). It did work and, after installing Bumblebee in tty (because it wouldn't boot when it was first installed), it worked marvelously for a little less than a week. However, I restarted it last night and got the Could not write bytes: Broken pipes error. (I see it's a very common error, but I've looked at the majority of the suggested Similar Questions already.) I followed what I could find online, followed those instructions (making sure to not install any sort of graphics drivers other than what Bumblebee provides), and it just seems to go further and further downhill. I'm afraid I didn't write the exact steps to get to this point (it was late by the time I gave up the night before), but it involved reinstalling lightdm, xorg (and xserver?), and Bumblebee. I then changed the Bumblebee.conf file so that Device=nvidia. I'm pretty new to Linux in general (I've used it since 10.04, but I hadn't had issues up until this computer, so it let me stay a newbie), so I'm not exactly sure what log files to look at to find the errors to look up. However, I did look at lshw and noticed that displays was marked as unassigned. Also, if I try to start lightdm using the command line, it always stops at Stopping Mount network filesystems. I should note that there isn't an xorg.conf file, and no .Xauthority. I would really, really prefer not to reinstall 12.04 if possible. I managed to get grub to display only a short time ago, and I can't boot to the dvd drive unless I go into the BIOS settings and manually change the boot order (that was an issue from the beginning, before the Ubuntu install), and getting into those settings often means rebooting several times due to the fact that the window to get to it is extremely small. I have most of what I need backed up, however, in case it does get to that point. If I really have to, I can just use the latest Ubuntu version instead of the LTS, but the reason I chose 12.04 in the first place is because I need something stable-ish, and Windows isn't suitable to what I need to do. I should note that the reason I restarted last night in the first place was that it wasn't charging the battery, and the wifi kept on going out. Hardware: Nvidia GeForce GT 750M Intel HD graphics 4600

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• WebAPI and MVC4 and OData

  - by Aligned

  I was looking closer into WebAPI, specificially how to use OData to avoid writing GetCustomerByCustomerId(int id) methods all over the place. I had problems just returning IQueryable<T> as some sites suggested in the WebpAPI (Assembly System.Web.Http.dll, v4.0.0.0).  I think things changed in the release version and the blog posts are still out of date. There is no [Queraable] as the answer to this question suggests. Once I get WebAPI.Odata Nuget package, and added the [Queryable] to the method http://localhost:57146/api/values/?$filter=Id%20eq%201 worked (don’t forget the ‘$’). Now the main question is whether I should do this and how to stop logged in users from sniffing the url and getting data for other users. I John V. Peterson has a post on securing WebAPI with headers and intercepting the call at that point. He had an update to use HttpMessageHandlers instead. I think I’ll use this to force the call to contain some kind of unique code for the user, but I’m still thinking about this. I will not expose this to the public, just to my calls with-in my Forms Authentication areas. Other links: http://robbincremers.me/2012/02/16/building-and-consuming-rest-services-with-asp-net-web-api-and-odata-support/ ~lots of good information John V Peterson example: https://github.com/johnvpetersen/ASPWebAPIExample ~ all data access goes through the WebApi and the web client doesn’t have a connection string ~ There is code library for calling the WebApi from MVC using the HttpClient. It’s a great starting point http://blogs.msdn.com/b/alexj/archive/2012/08/15/odata-support-in-asp-net-web-api.aspx ~ Beta (9/18/2012) Nuget package to help with what I want to do? ~ has a sample code project with examples http://blogs.msdn.com/b/alexj/archive/2012/08/15/odata-support-in-asp-net-web-api.aspx http://blogs.msdn.com/b/alexj/archive/2012/08/21/web-api-queryable-current-support-and-tentative-roadmap.aspx http://stackoverflow.com/questions/10885868/asp-net-mvc4-rc-web-api-odata-filter-not-working-with-iqueryable JSON, pass the correct format in the header (Accept: application/json). $format=JSON doesn’t appear to be working. Async methods built into WebApi! Look for the GetAsync methods.

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• The Uganda .NET Usergroup meeting for January 2011 - a look back.

  - by Malisa L. Ncube

  We had a very interesting meeting on Friday 28th last week. We had 10 attendees and two speakers. The first topic presented was Cloud Computing, presented by Allan Rwakatungu @arwakatungu who works with MTN Uganda. He gave a very brilliant outline of how Cloud computing and service oriented applications had begun changing the platform for operating business and the costs it saves because of scalability and elasticity. He went on to demonstrate the steps you would take if you are beginning a new Windows Azure project. He explained the history and evolution of the Windows Azure, SQL Azure and cloud services offered by Amazon and google.com. The attendees had many questions to ask (obviously), but they were all answered very well. We once again thank Allan, for taking time to prepare the presentation and demonstrating for us. We recorded a video on the entire presentation and after doing some editing we will publish it. One wish which was echoed by most members was that Microsoft should open the cloud services and development for Africa. Microsoft currently does not even have servers here in Africa and so far, that does not put African developers in the same platform as other developers in other continents. Now is the time considering the improvements in network speeds and joining of the Seacom network and broadband.   I presented on Parallelism and Multithreading using .NET 4.0, I also gave some details on the language changes in C# 5.0 and the async keyword and the TaskEx class. I explained the Task, Scheduling of parallel tasks and demonstrated problems that may arise from using parallelism inappropriately. I also demonstrated the performance improvements that may be achieved by taking advantage of multi-core processors. You may download the presentation on Parallelism and Multi-threading from here. The resolution of the meeting was that we should meet more than once a month and begin other activities which should be more fun. e.g. Geek Dinner, Geek Beer or CodeCamp. Based on that we all agreed we shall have a mid-month meeting starting from February. Cheers folks! del.icio.us Tags: .net,usergroup,cloud computing,parallelism,multi-threading

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• Various issues linked to my CD drive, when it has a disc in it

  - by Voyagerfan5761

  When I go to the Desktop and click on a media icon (for my flash drive, a CD, whatever it is), the following problems occur, in this approximate sequence: Nautilus will close if it's open. the desktop icons disappear my Window List shows a button that says "Starting File Manager" the icons reappear the button in Window List disappears Because of this problem, I can no longer drag and drop media, nor can I right-click to perform actions such as "Eject" and "Safely Remove Drive". The same symptoms occur if I click a media icon (that is also present on the desktop) in Nautilus' Computer view, though notably not if I click in the places list on the left. I have confirmed that this problem happens only if there is a CD in the drive (Matshita UJDA360). Also, inserting a disc into the CD drive appears to kill all running programs and restart Nautilus (or X; I'm not sure). Applications like Brasero and Rhythmbox will not start while there is a disc in the drive. Removing the disc doesn't result in the list of media updating; it must be forced to update by clicking on one of the desktop icons and going through one of the above-described cycles. It doesn't seem to matter what type of disc is in the drive. This has happened with CD-RWs I burned years ago using Roxio on Windows XP, the Ubuntu disc I installed from (burned with InfraRecorder Portable under Windows XP), and the retail game disc for Star Trek Armada II. The first indication of a problem was Brasero dying when I tried to insert a disc for erasure and rewriting. Since then, I've drafted several different questions on various issues, finally combining them into this one when I realized that having a CD in the drive was the common link. Could this be a simple driver issue? If Ubuntu is dynamically detecting my hardware on boot, can I specify drivers for devices that I know will be a problem if the default files are used? I'm beginning to think that my laptop, an old Dell Inspiron 2650, is just too old or proprietary-driver-hungry (or something, maybe RAM-starved) for Ubuntu and Windows XP to play nicely alongside each other. Or maybe I just need to carefully take my wall-wart machine to a coffee shop for an afternoon so I can download updates and such from the Internet, as I lack a home connection.

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• Understanding clojure keywords

  - by tjb1982

  I'm taking my first steps with Clojure. Otherwise, I'm somewhat competent with JavaScript, Python, Java, and a little C. I was reading this artical that describes destructuring vectors and maps. E.g. => (def point [0 0]) => (let [[x y] point] => (println "the coordinates are:" x y)) the coordinates are: 0 0 but I'm having a difficult time understanding keywords. At first glance, they seem really simple, as they just evaluate to themselves: => :test :test But they seem to be used is so many different ways and I don't understand how to think about them. E.g., you can also do stuff like this: => (defn full-name [& {first :first last :last}] => (println first last)) => (full-name :first "Tom" :last "Brennan") Tom Brennan nil This doesn't seem intuitive to me. I would have guessed the arguments should have been something more like: (full-name {:first "Tom" :last "Brennan"}) because it looks like in the function definition that you're saying "no required arguments, but a variable number of arguments comes in the form of a single map". But it seems more like you're saying "no required arguments, but a variable number of arguments comes which should be a list of alternating keywords and values... ?" I'm not really sure how to wrap my brain around this. Also, things like this confuse me too: => (def population {:humans 5 :zombies 1000}) => (:zombies population) 1000 => (population :zombies) 1000 How do maps and keywords suddenly become functions? If I could get some clarification on the use of keywords in these two examples, that would be really helpful. Update I've also seen http://stackoverflow.com/questions/3337888/clojure-named-arguments and while the accepted answer is a great demonstration of how to use keywords with destructuring and named arguments, I'm really looking more for understanding how to think about them--why the language is designed this way and how I can best internalize their use.

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• What should filenames and URLs of images contain for SEO benefit?

  - by Baumr

  We know that good site architecture usually looks like this: example-company.com/ example-company.com/about/ example-company.com/contact/ example-company.com/products/ example-company.com/products/category/ example-company.com/products/category/productname/ Now, when it comes to Google Image search, it is clear that the img alt tag, filename/URL, and surrounding text (captions, headings, paragraphs) have an effect on ranking. I want to ask about the filename of the images that we should use (e.g. product-photo.jpg). ...but first about the URL: Often web developers stick all images in a single folder in the root: example-company.com/img/ — and I have stopped doing that. (I don't want to get into it, but basically, it seems more semantic for images which make up part of the content at each sub-directory) However, when all images appear in a folder, I feel that their filename needs to reflect what they are a bit more than usual, for example: example-company.com/img/example-company-productname-category.jpg It's a longer filename than just product.png, but as long as it's relevant, I see no problem with regards to SEO (unless you're keyword stuffing), and it could even help rank for keywords: "example company" "productname" "category" So no questions there. But what about when we have places images in the site architecture we outlined at the beginning? In other words, what if image URL paths look like this: example-company.com/products/category/productname/productname.jpg My question is, should the URL be kept short like above and only have the "productname" (and some descriptive keywords) as part of it's filename? Or, should it also include the "example-company" and "category"? Like so: example-company.com/products/category/productname/example-company-category-productname.jpg That seems much longer, and redundant when we look at the URL, but here are a few considerations. Images are often downloaded onto computers, and, to the average user, they lose their original URL and thus — it isn't clear where they came from. Also, some social networks, forums, and other platforms leave the filename intact when uploaded. (Many others rewrite it, for example, Pinterest and Facebook.) Another consideration, will this really help (even if ever so slightly) rank in Google Image Search, or at least inform Google that the product is something specific to the "example-company"? For example, what if this product can only be bought at this store and is the flagship product? In addition to an abundance of internal links to this product page, would having the "example company" name and "category" help it appear in "example company" searches? In other words, is less more?

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• How to discriminate from two nodes with identical frequencies in a Huffman's tree?

  - by Omega

  Still on my quest to compress/decompress files with a Java implementation of Huffman's coding (http://en.wikipedia.org/wiki/Huffman_coding) for a school assignment. From the Wikipedia page, I quote: Create a leaf node for each symbol and add it to the priority queue. While there is more than one node in the queue: Remove the two nodes of highest priority (lowest probability) from the queue Create a new internal node with these two nodes as children and with probability equal to the sum of the two nodes' probabilities. Add the new node to the queue. The remaining node is the root node and the tree is complete. Now, emphasis: Remove the two nodes of highest priority (lowest probability) from the queue Create a new internal node with these two nodes as children and with probability equal to the sum of the two nodes' probabilities. So I have to take two nodes with the lowest frequency. What if there are multiple nodes with the same low frequency? How do I discriminate which one to use? The reason I ask this is because Wikipedia has this image: And I wanted to see if my Huffman's tree was the same. I created a file with the following content: aaaaeeee nnttmmiihhssfffouxprl And this was the result: Doesn't look so bad. But there clearly are some differences when multiple nodes have the same frequency. My questions are the following: What is Wikipedia's image doing to discriminate the nodes with the same frequency? Is my tree wrong? (Is Wikipedia's image method the one and only answer?) I guess there is one specific and strict way to do this, because for our school assignment, files that have been compressed by my program should be able to be decompressed by other classmate's programs - so there must be a "standard" or "unique" way to do it. But I'm a bit lost with that. My code is rather straightforward. It literally just follows Wikipedia's listed steps. The way my code extracts the two nodes with the lowest frequency from the queue is to iterate all nodes and if the current node has a lower frequency than any of the two "smallest" known nodes so far, then it replaces the highest one. Just like that.

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• Blender to 3ds max to cal3d format

  - by Kaliber64

  There are quite a few questions on cal3d but they are old and don't apply anymore. In Blender(must be 2.49a for python script to work!!!): I have a scene with 7 meshes, 1 armature, 10 bones. I tried going to one mesh to simplify it but doesn't change anything. I found a small blend file that was used for cal3d and it exported just fine. So I tried to copy it's setup with no success. EDIT*8/13/2012 In the last week here is what I have found so far. I made the mesh in the newest blender(2.62?) and exported it to import it in the old one(2.49a). Did an animation in the old one because importing new blend files to old blenders, its just said it would lose keyframe data and all was good. And then you get the last problem of it not exporting meshes. BUT I found that meshes made in the old one export regardless. I can't find any that won't export. So if I used the old blender to remake my model I could get it to export :) At this point I found a modified release of cal3d (because the most core model variable would not initiate as I made a really small test subject in old blender instead of remaking my big one which took 4 hours.) which fixes the morph objects and adds what cal3d left off with. Under their license they have to release the modification but it has no documentation so I have to figure it out on my own. Its mostly the same. But with this lib it came with a 3ds max exporter. My question now is how do I transfer armature and mesh information from blender to 3ds max in order to export into cal3d format. Every time I try the models are see through and small and there are no bones. The formats I have tried to import are .3ds .obj(mesh only) and COLLADA. In all of them the mesh is invisible and no bones. It says the default texture is on so I should be able to see it. All the vertices are present I found a vertex highlighter so I can see those. If any of this is confusing let me know so I can clear it up. Its late .<=sleep.

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• What location to put bootloader, when running multiple drives and partition

  - by Matt G

  I have Win8 on my desktop, where a 120G SSD is used to run windows and some select applications, while I have a 2TB HDD to provide basic file storage and where possible, install applications instead of on the SSD. I want to install Ubuntu on a new partition of the HDD (I allocated 300GB, with 5GB swap file). I've used a USB to install the OS, which seemed to have done the job. However, after prompting for a restart, I can no longer boot to ubuntu. During instillation I was confused about where to install the "boot loader instillation". I ended up selecting "/dev/stb" because I figured I would be able to boot with BIOS by selecting the HDD drive as a priority over the SSD. The bootloader is a large part of where I think I went wrong. My partition system looked something like this: /dev/sta ... //SSD ~120 GB /dev/sta1 NTFS (350 MB) //Win8System /dev/sta2 NTFS (118 GB) //Win8C-Drive /dev/stb ... //HDD ~2TB /dev/stb1 NTFS (1563 GB) //FileStorage /dev/stb5 Free Space (300 GB) //Space I want to use for Linux (NOTE: Created two partitions from the 300GB, ~5GB and 295GB. stb5,stb6.) It'd be great if I could get an explanation of what drive you'd select for the boot loader and why, and what selections won't work with regards to the Boot Loader Instillation. I think I understand what Grub is, but I have no idea on how to use it, or play around with it. I seem to be able to get back into OS from my usb, however I believe it's just showing me a preview/trial of Ubuntu (ie, can't access any of the system NTFS drives). Note, if I try to install from the USB again, it will recognize that a version of Ubuntu 13.10 exists on the system. Apologies in advance, have used windows all my life, don't really know to much about Linux at all. Did have a brief skim over some similar questions, didn't find anything too useful. - Where to install bootloader when installing Ubuntu as secondary OS? - ubuntu 12.10 dual boot with windows 8 on two hdds - Dual-boot Windows 7 and Ubuntu on two SSDs with UEFI

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• How can I make a universal construction more efficient?

  - by VF1

  A "universal construction" is a wrapper class for a sequential object that enables it to be linearized (a strong consistency condition for concurrent objects). For instance, here's an adapted wait-free construction, in Java, from [1], which presumes the existence of a wait-free queue that satisfies the interface WFQ (which only requires one-time consensus between threads) and assumes a Sequential interface: public interface WFQ<T> // "FIFO" iteration { int enqueue(T t); // returns the sequence number of t Iterable<T> iterateUntil(int max); // iterates until sequence max } public interface Sequential { // Apply an invocation (method + arguments) // and get a response (return value + state) Response apply(Invocation i); } public interface Factory<T> { T generate(); } // generate new default object public interface Universal extends Sequential {} public class SlowUniversal implements Universal { Factory<? extends Sequential> generator; WFQ<Invocation> wfq = new WFQ<Invocation>(); Universal(Factory<? extends Sequential> g) { generator = g; } public Response apply(Invocation i) { int max = wfq.enqueue(i); Sequential s = generator.generate(); for(Invocation invoc : wfq.iterateUntil(max)) s.apply(invoc); return s.apply(i); } } This implementation isn't very satisfying, however, since it presumes determinism of a Sequential and is really slow. I attempted to add memory recycling: public interface WFQD<T> extends WFQ<T> { T dequeue(int n); } // dequeues only when n is the tail, else assists other threads public interface CopyableSequential extends Sequential { CopyableSequential copy(); } public class RecyclingUniversal implements Universal { WFQD<CopyableSequential> wfqd = new WFQD<CopyableSequential>(); Universal(CopyableSequential init) { wfqd.enqueue(init); } public Response apply(Invocation i) { int max = wfqd.enqueue(i); CopyableSequential cs = null; int ctr = max; for(CopyableSequential csq : wfq.iterateUntil(max)) if(--max == 0) cs = csq.copy(); wfqd.dequeue(max); return cs.apply(i); } } Here are my specific questions regarding the extension: Does my implementation create a linearizable multi-threaded version of a CopyableSequential? Is it possible extend memory recycling without extending the interface (perhaps my new methods trivialize the problem)? My implementation only reduces memory when a thread returns, so can this be strengthened? [1] provided an implementation for WFQ<T>, not WFQD<T> - one does exist, though, correct? [1] Herlihy and Shavit, The Art of Multiprocessor Programming.

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• Push-Based Events in a Services Oriented Architecture

  - by Colin Morelli

  I have come to a point, in building a services oriented architecture (on top of Thrift), that I need to expose events and allow listeners. My initial thought was, "create an EventService" to handle publishing and subscribing to events. That EventService can use whatever implementation it desires to actually distribute the events. My client automatically round-robins service requests to available service hosts which are determined using Zookeeper-based service discovery. So, I'd probably use JMS inside of EventService mainly for the purpose of persisting messages (in the event that a service host for EventService goes down before it can distribute the message to all of the available listeners). When I started considering this, I began looking into the differences between Queues and Topics. Topics unfortunately won't work for me, because (at least for now), all listeners must receive the message (even if they were down at the time the event was pushed, or hadn't made a subscription yet because they haven't completed startup (during deployment, for example) - messages should be queued until the service is available). However, I don't want EventService to be responsible for handling all of the events. I don't think it should have the code to react to events inside of it. Each of the services should do what it needs with a given event. This would indicate that each service would need a JMS connection, which questions the value of having EventService at all (as the services could individually publish and subscribe to JMS directly). However, it also couples all of the services to JMS (when I'd rather that there be a single service that's responsible for determining how to distribute events). What I had thought was to publish an event to EventService, which pulls a configuration of listeners from some configuration source (database, flat file, irrelevant for now). It replicates the message and pushes each one back into a queue with information specific to that listener (so, if there are 3 listeners, 1 event would become 3 events in JMS). Then, another thread in EventService (which is replicated, running on multiple hots) would be pulling from the queue, attempting to make the service call to the "listener", and returning the message to the queue (if the service is down), or discarding the message (if the listener completed successfully). tl;dr If I have an EventService that is responsible for receiving events and delegating service calls to "event listeners," (which are really just endpoints on other services), how should it know how to craft the service call? Should I create a generic "Event" object that is shared among all services? Then, the EventService can just construct this object and pass it to the service call. Or is there a better answer to this problem entirely?

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• Certification Notes: 70-583 Designing and Developing Windows Azure Applications

  - by BuckWoody

  Last Updated: 02/01/2011 It’s time for another certification, and we’ve just release the 70-583 exam on Windows Azure. I’ve blogged my “study plans” here before on other certifications, so I thought I would do the same for this one. I’ll also need to take exam 70-513 and 70-516; but I’ll post my notes on those separately. None of these are “brain dumps” or any questions from the actual tests - just the books, links and notes I have from my studies. I’ll update these references as I’m studying, so bookmark this site and watch my Twitter and Facebook posts for when I’ll update them, or just subscribe to the RSS feed. A “Green” color on the check-block means I’ve done that part so far, red means I haven’t. First, I need to refresh my memory on some basic coding, so along with the Azure-specific information I’m reading the following general programming books: Introducing Microsoft .NET (Pro-Developer): link   Head First C#, 2E: A Learner's Guide to Real-World Programming with Visual C# and .NET: link Microsoft Visual C# 2008 Step by Step: link  c The first place to start is at the official site for the certification. link c On that page you’ll find several resources, and the first you should follow is the “Save to my learning” so you have a place to track everything. Then click the “Related Learning Plans” link and follow the videos and read the documentation in each of those bullets. There are six areas on the learning plan that you should focus on - make sure you open the learning plan to drill into the specifics. c Designing Data Storage Architecture (18%) Books I’m Reading: Links: My Notes: c Optimizing Data Access and Messaging (17%) Books I’m Reading: Links: My Notes: c Designing the Application Architecture (19%) Books I’m Reading: Applied Architecture Patterns on the Microsoft Platform: link Links: My Notes: c Preparing for Application and Service Deployment (15%) Books I’m Reading: Links: My Notes: c Investigating and Analyzing Applications (16%) Books I’m Reading: Links: My Notes: c Designing Integrated Solutions (15%) Books I’m Reading: Applied Architecture Patterns on the Microsoft Platform (2nd mention) Links: My Notes:

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• Manic Monday - More OpenWorld Solaris Sessions: Developers, Cloud, Customer Insights, Hardware Optimization

  - by Larry Wake

  We're overflowing with Monday sessions; literally more than one person can take in. Learn more about what's new in Oracle Solaris Studio, hear about the latest x86 and SPARC hardware optimizations, get some insights on cloud deployment strategies, and find out from your peers what they're doing with Oracle Solaris. If you're an OpenWorld attendee, go to to Schedule Builder to guarantee your space in any session or lab. See yesterday's blog post and the "Focus on Oracle Solaris" guide for even more sessions. Monday, October 1st: 10:45 AM - Maximizing Your SPARC T4 Oracle Solaris Application Performance(CON6382,  Marriott Marquis - Golden Gate C3) Hear how customers and commercial software partners have reached peak performance on SPARC T4 servers and engineered systems with Oracle Solaris Studio and its latest tools for analyzing, reporting, and improving runtime performance: Autoparallelizing, high-performance compilers Performance Analyzer (used to find performance hotspots) Thread Analyzer (to expose data races and deadlocks) Code Analyzer (used to discover latent memory corruption issues) 10:45 Cloud Formation: Implementing IaaS in Practice with Oracle Solaris(CON8787, Moscone South 302) Decisions, decisions--at the same time, we've got a session that covers why Oracle Solaris is the ideal OS for public or private clouds, IaaS or PaaS, with built-in features for elastic infrastructure, unrivaled security, superfast installation and deployment, nonstop availability, and crystal-clear observability. This session will include a customer study on how Oracle Solaris is used in the cloud today to implement the Oracle stack. 12:15 PM - Customer Insight: Oracle Solaris on Oracle Exadata, Oracle Exalogic, and SPARC SuperCluster(CON8760, Moscone South 270) Hear from customers what benefits they have realized from using the Oracle stack on Oracle Exadata and Oracle’s SPARC SuperCluster and from using Oracle Solaris on those engineered systems, taking advantage of built-in lightweight OS virtualization (Zones), enterprise reliability and scale, and other key features. 1:45 PM - Case Study: Mobile Tornado Uses Oracle Technology for Better RAS and TCO?(CON4281, Moscone West 2005) Mobile Tornado develops and markets instant communication platforms, replacing traditional radio networks with cellular networks. Its critical concern is uptime. Find out how they've used Oracle Solaris, Netra SPARC T4, and Oracle Solaris Cluster, including Oracle Solaris ZFS and Zones, for their Oracle Database deployments to improve reliability and drive down cost. 3:15 PM - Technical Panel: Developing High Performance Applications on Oracle Solaris(CON7196, Marriott Marquis - Golden Gate C2) Engineers from the Oracle Solaris, Oracle Database, and Oracle Tuxedo development teams, and Oracle ISV Engineering discuss how they develop high-performance enterprise applications that take advantage of Oracle's SPARC and x86 servers, with Oracle Solaris Studio and new Oracle Solaris 11 features. Topics will include developer tools, parallel frameworks, best practices, and methodologies, as well as insights and case studies on parallelizing and optimizing application performance on Oracle Solaris. Bring your best questions! 3:15 PM -  x86 Power Management with Oracle Solaris: Current State, Opportunities, and Future(CON6271, Moscone West 2012) Another option for this time slot: learn about how Intel Xeon and Oracle Solaris work together to reduce server power consumption. This presentation addresses some of the recent power management improvements in Oracle Solaris, opportunities to further improve energy efficiency, and some future directions for Oracle Solaris power management.

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• Wrapping REST based Web Service

  - by PaulPerry

  I am designing a system that will be running online under Microsoft Windows Azure. One component is a REST based web service which will really be a wrapper (using proxy pattern) which calls the REST web services of a business partner, which has to do with BLOB storage (note: we are not using azure storage). The majority of the functionality will be taking a request, calling our partner web service, receiving the request and then passing that back to the client. There are a number of reasons for doing this, but one of the big ones is that we are going to support three clients: our desktop application (win and mac), mobile apps (iOS), and a web front end. Having a single API which we then send to our partner protects us if that partner ever changes. I want our service to support both JSON and XML for the data transfer format, JSON for web and probably XML for the desktop and mobile (we already have an XML parser in those products). Our partner also supports both of these formats. I was planning on using ASP.NET MVC 4 with the Web API. As I design this, the thing that concerns me is the static type checking of C#. What if the partner adds or removes elements from the data? We can probably defensively code for that, but I still feel some concern. Also, we have to do a fair amount of tedious coding, to setup our API and then to turn around and call our partner’s API. There probably is not much choice on it though. But, in the back of my mind I wonder if maybe a more dynamic language would be a better choice. I want to reach out and see if anybody has had to do this before, what technology solutions they have used to (I am not attached to this one, these days Azure can host other technologies), and if anybody who has done something like this can point out any issues that came up. Thanks! Researching the issue seems to only find solutions which focus on connecting a SOAP web service over a proxy server, and not what I am referring to here. Note: Cross posted (by suggestion) from http://stackoverflow.com/questions/11906802/wrapping-rest-based-web-service Thank you!

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• Ray Intersecting Plane Formula in C++/DirectX

  - by user4585

  I'm developing a picking system that will use rays that intersect volumes and I'm having trouble with ray intersection versus a plane. I was able to figure out spheres fairly easily, but planes are giving me trouble. I've tried to understand various sources and get hung up on some of the variables used within their explanations. Here is a snippet of my code: bool Picking() { D3DXVECTOR3 vec; D3DXVECTOR3 vRayDir; D3DXVECTOR3 vRayOrig; D3DXVECTOR3 vROO, vROD; // vect ray obj orig, vec ray obj dir D3DXMATRIX m; D3DXMATRIX mInverse; D3DXMATRIX worldMat; // Obtain project matrix D3DXMATRIX pMatProj = CDirectXRenderer::GetInstance()->Director()->Proj(); // Obtain mouse position D3DXVECTOR3 pos = CGUIManager::GetInstance()->GUIObjectList.front().pos; // Get window width & height float w = CDirectXRenderer::GetInstance()->GetWidth(); float h = CDirectXRenderer::GetInstance()->GetHeight(); // Transform vector from screen to 3D space vec.x = (((2.0f * pos.x) / w) - 1.0f) / pMatProj._11; vec.y = -(((2.0f * pos.y) / h) - 1.0f) / pMatProj._22; vec.z = 1.0f; // Create a view inverse matrix D3DXMatrixInverse(&m, NULL, &CDirectXRenderer::GetInstance()->Director()->View()); // Determine our ray's direction vRayDir.x = vec.x * m._11 + vec.y * m._21 + vec.z * m._31; vRayDir.y = vec.x * m._12 + vec.y * m._22 + vec.z * m._32; vRayDir.z = vec.x * m._13 + vec.y * m._23 + vec.z * m._33; // Determine our ray's origin vRayOrig.x = m._41; vRayOrig.y = m._42; vRayOrig.z = m._43; D3DXMatrixIdentity(&worldMat); //worldMat = aliveActors[0]->GetTrans(); D3DXMatrixInverse(&mInverse, NULL, &worldMat); D3DXVec3TransformCoord(&vROO, &vRayOrig, &mInverse); D3DXVec3TransformNormal(&vROD, &vRayDir, &mInverse); D3DXVec3Normalize(&vROD, &vROD); When using this code I'm able to detect a ray intersection via a sphere, but I have questions when determining an intersection via a plane. First off should I be using my vRayOrig & vRayDir variables for the plane intersection tests or should I be using the new vectors that are created for use in object space? When looking at a site like this for example: http://www.tar.hu/gamealgorithms/ch22lev1sec2.html I'm curious as to what D is in the equation AX + BY + CZ + D = 0 and how does it factor in to determining a plane intersection? Any help will be appreciated, thanks.

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• determine collision angle on a rotating body

  - by jorb

  update: new diagram and updated description I have a contact listener set up to try and determine the side that a collision happened at relative to the a bodies rotation. One way to solve this is to find the value of the yellow angle between the red and blue vectors drawn above. The angle can be found by taking the arc cosine of the dot product of the two vectors (Evan pointed this out). One of my points of confusion is the difference in domain of the atan2 function html canvas coordinates and the Box2d rotation information. I know I have to account for this somehow... SS below questions: Does Box2D provide these angles more directly in the collision information? Am I even on the right track? If so, any hints? I have the following javascript so far: Ship.prototype.onCollide = function (other_ent,cx,cy) { var pos = this.body.GetPosition(); //collision position relative to body var d_cx = pos.x - cx; var d_cy = pos.y - cy; //length of initial vector var len = Math.sqrt(Math.pow(pos.x -cx,2) + Math.pow(pos.y-cy,2)); //body angle - can over rotate hence mod 2*Pi var ang = this.body.GetAngle() % (Math.PI * 2); //vector representing body's angle - same magnitude as the first var b_vx = len * Math.cos(ang); var b_vy = len * Math.sin(ang); //dot product of the two vectors var dot_prod = d_cx * b_vx + d_cy * b_vy; //new calculation of difference in angle - NOT WORKING! var d_ang = Math.acos(dot_prod); var side; if (Math.abs(d_ang) < Math.PI/2 ) side = "front"; else side = "back"; console.log("length",len); console.log("pos:",pos.x,pos.y); console.log("offs:",d_cx,d_cy); console.log("body vec",b_vx,b_vy); console.log("body angle:",ang); console.log("dot product",dot_prod); console.log("result:",d_ang); console.log("side",side); console.log("------------------------"); }

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• Using HBase or Cassandra for a token server

  - by crippy

  I've been trying to figure out how to use HBase/Cassandra for a token system we're re-implementing. I can probably squeeze quite a lot more from MySQL, but it just seems it has come to clinging on to the wrong tool for the task just because we know it well. Eventually will hit a wall (like happened to us in other areas). Naturally I started looking into possible NoSQL solutions. The prominent ones (at least in terms of buzz) are HBase and Cassandra. The story is more or less like this: A user can send a gift other users. Each gift has a list of recipients or is public in which case limited by number or expiration date For each gift sent we generate some token that uniquely identifies that gift. For each gift we track the list of potential recipients and their current status relating to that gift (accepted, declinded etc). A user can request to see all his currently pending gifts A can request a list of users he has sent a gift to today (used to limit number of gifts sent) Required the ability to "dump" or "ignore" expired gifts (x day old gifts are considered expired) There are some other requirements but I believe the above covers the essentials. How would I go and model that using HBase or Cassandra? Well, the wall was performance. A few 10s of millions of records per day over 2 tables kept for 2 weeks (wish I could have kept it for more but there was no way). The response times kept getting slower and slower until eventually we had to start cutting down number of days we kept data. Caching helps here but it's not an ideal solution since a big part of the ops are updates. Also, as I hinted in my original post. We use MySQL extensively. We know exactly what it can and can't do both in naive implementations followed by native partitioning and finally by horizontally sharding our dataset on the application level to reside on multiple DB nodes. It can be done, but that's not really what I'm trying to get from this. I asked a very specific question about designing a solution using a NoSQL solution since it's very hard to find examples for designs out there. Brainlag, not trying to come off as rude. I actually appreciate it a lot that you are the only one who even bothered to respond. but I see it over and over again. People ask questions and others assume they have no idea what they're talking about and give an irrelevant answer. Ignore RDBMS please. The question is about nosql.

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• CES 2011–Microsoft Keynote Impressions

  - by guybarrette

  Microsoft has been kicking off the CES for a number of years by doing a keynote the evening of the event first day.  This year, SteveB talked about Xbox, Kinect, Windows 7 new laptops, Surface 2 and Windows vNext running on the ARM architecture. Some of the design of the new laptops showed are quite amazing.  This one has a dual screen with no physical keyboard.  The image is split between both screens.  A software keyboard appears when you place your 10 fingers on the lower screen. This one from Samsung has a sliding keyboard somewhat like numerous cell phones have. What I found the most amazing is that Intel was able to miniaturized a full Intel architecture (CPU, motherboard, memory) in a tiny form factor.  Imagine having the power of a full PC running .NET apps in a Zune/iPod form factor! They also showed V2 of the Surface device.  This one is called the Samsung SUR40 for Surface PC.  It’s much sleeker and it will likely loose the BAT (Big Ass Table) moniker  More info here SteveB announced that Windows vNext will run on ARM chips.  I’m intrigued by this announcement (you can read about it here) and I have many questions: -In the past ARM devices were slow, what now makes the ARM architecture able to run Windows? -ARM is 32-bit only, I think. -Does this mean that Intel wasn't able to provide such a lightweight architecture or simply that they weren't interested? -From what I understand, apps would need to be recompiled for ARM. Will we need to do that from an ARM PC or could it be done natively on Intel or on an Intel PC running in an ARM VM?  VS 2012? Ahhhh, smells like a cool PDC is coming up    Clearly it looks like PC have enough power for most of us right now and that the race is now about miniaturization, power consumption and battery life. You can watch the Microsoft CES 2011 keynote here var addthis_pub="guybarrette";

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• SQL SERVER – Fix: Error: 147 An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or a select list, and the column being aggregated is an outer reference

  - by pinaldave

  Everybody was beginner once and I always like to get involved in the questions from beginners. There is a big difference between the question from beginner and question from advanced user. I have noticed that if an advanced user gets an error, they usually need just a small hint to resolve the problem. However, when a beginner gets error he sometimes sits on the error for a long time as he/she has no idea about how to solve the problem as well have no idea regarding what is the capability of the product. I recently received a very novice level question. When I received the problem I quickly see how the user was stuck. When I replied him with the solution, he wrote a long email explaining how he was not able to solve the problem. He thanked multiple times in the email. This whole thing inspired me to write this quick blog post. I have modified the user’s question to match the code with AdventureWorks as well simplified so it contains the core content which I wanted to discuss. Problem Statement: Find all the details of SalesOrderHeaders for the latest ShipDate. He comes up with following T-SQL Query: SELECT * FROM [Sales].[SalesOrderHeader] WHERE ShipDate = MAX(ShipDate) GO When he executed above script it gave him following error: Msg 147, Level 15, State 1, Line 3 An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or a select list, and the column being aggregated is an outer reference. He was not able to resolve this problem, even though the solution was given in the query description itself. Due to lack of experience he came up with another version of above query based on the error message. SELECT * FROM [Sales].[SalesOrderHeader] HAVING ShipDate = MAX(ShipDate) GO When he ran above query it produced another error. Msg 8121, Level 16, State 1, Line 3 Column ‘Sales.SalesOrderHeader.ShipDate’ is invalid in the HAVING clause because it is not contained in either an aggregate function or the GROUP BY clause. What he wanted actually was the SalesOrderHeader all the Sales shipped on the last day. Based on the problem statement what the right solution is as following, which does not generate error. SELECT * FROM [Sales].[SalesOrderHeader] WHERE ShipDate = (SELECT MAX(ShipDate) FROM [Sales].[SalesOrderHeader]) Well, that’s it! Very simple. With SQL Server there are always multiple solution to a single problem. Is there any other solution available to the problem stated? Please share in the comment. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Error Messages, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Changing Silverlight application themes at runtime

  We have received a lot of questions how can the application theme be changed at run time. The most important thing here to mark is that each time the application theme is changed all the controls should be re-drawn. Without going into too much detail, we could explain the application themes as a mechanism to replace the content of the Generic.xaml file in every loaded Telerik assembly at runtime. This does not affect the controls that already have default style applied, hence the need to create new instances. Because in the Silverlight applications the RootVisual cannot be changed at run time, we need a way to reset the application UI. The following code is in App.xaml.cs. private void Application_Startup(object sender, StartupEventArgs e)     {           // Before:           // this.RootVisual = new MainPage();            this.RootVisual = new Grid();         this.ResetRootVisual();     }        public void ResetRootVisual()     {         var rootVisual = Application.Current.RootVisual as Grid;         rootVisual.Children.Clear();         rootVisual.Children.Add(new MainPage());     }   In Application_Startup() instead of creating new MainPage UserControl instance as RootVisual, we create a new Grid panel, that will contain the MainPage UserControl. In the ResetRootVisual() method we create the instance of MainPage and add it to the RootVisual panel. Then we have to create a method in the code behind which will set StyleManager.ApplicationTheme and then will call the ResetRootVisual() method: private void ChangeApplicationTheme(Theme theme) {     StyleManager.ApplicationTheme = theme;     (Application.Current as App).ResetRootVisual(); }   Here you can find an example which illustrates the described implementation of a Silverlight theme. For more information please refer to Teleriks online demos for Silverlight, the demos for WPF and help documentation for WPF and help documentation for Silverlight. 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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• AVIO Academy - ADF w/Oracle BPM

  - by BPMWarrior

  Oracle Platinum Partner AVIO Consulting is excited to announce the launch of the industry’s first ADF with Oracle BPM developer training program.  This training program is for any prospects or customers that could benefit from a better understanding of Oracle ADF and Oracle BPM.    Visit the AVIO Academy website for an in-depth description of the new ADF with Oracle BPM Workshop .     What it is: ·         Industry’s first ADF with Oracle BPM training program ·         3-day workshop showcasing application development using ADF with Oracle BPM Suite   Training Purpose: Teaches developers how to use Oracle Application Development Framework (ADF) with the Oracle Business Process Management (BPM) Suite.  The workshop is the only one of its kind on the market today.  During the course, students gain a better understanding of Oracle ADF, and the nuances of making it work with Oracle BPM.   Course Overview This course in AVIO’s BPM series, consists of 11 hands-on lessons designed specifically for developers.   It provides a comprehensive overview of ADF and Oracle BPM concepts, and step-by-step easy to follow instructions for creating and integrating ADF user interfaces with Oracle BPM processes.  Students leave the workshop with the working versions of the projects they build for their future reference.  Rather than just frantically clicking through the lessons, concepts are thoroughly explained and demonstrated.  Students leave understanding the best practices AVIO established during years of developing ADF solutions for Oracle BPM and SOA.   AVIO Academy This new workshop is offered through AVIO Academy, the only program with curriculum specifically developed for the most recent version of the Oracle BPM Suite. The academy specializes in hands-on role based training that uses an organization’s own processes for a more practical learning experience.   Visit the AVIO Academy website for an in-depth description of the new ADF with Oracle BPM Workshop. If you have any questions please contact Brandon Dean at [email protected]

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