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  • I'm stuck on User Defined Session destop environment

    - by Dan
    I just installed Ubuntu for the first time dual boot so I get to choose Ubuntu or windows. I then changed the setting where is doesn't ask for my password when booting up. I then installed Edubuntu desktop package. I then hit system and logged out that way i could be at the loggin screen that also lets you select the desktop environment. Edubuntu was not there but User defined session was so i clicked that thinking that might be Edubuntu and logged in. Now im totally stuck. Only walpaper on the screen as i realize now that is normal for user defined session but there is no log out button to change desktop environments now and since I set it to not ask for password at boot up there is no option to change it at start up. If i hit ctrl+alt+del it only lets you shutdown, restart, suspend, or hybernate.... no logg out. I have hit every key on the keybourd hoping something will pop up. I thought this must be a simple noob mistake that there must be endless artiles about this so did searches on google and forums and was shocked to find nothing about this. My next step unless someone can help is to uninstall and reinstall.

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  • Set default owner/user

    - by Daniel Hollands
    I'm a web developer, and so have set-up an old machine in the office as an Ubuntu Server, for the purposes of testing websites. I've set-up LAMP and have created a /var/www folder, from which all my local sites are served. The issue is that of user permissions, i.e. any files that I copy into that folder (from my Windows machine via the network) automatically take on me (daniel) as their owner. The problem is that I want www-data to become the owner. I did some research and saw that it should be possible to use setuid (and setgid) to automatically set www-data as the owner of all files put into /var/www automatically, so far I've not had any luck making it work. Can someone help please? Thank you UPDATE: Would this do what I want it to do? Default file permissions for php user www-data UPDATE 2: I've kinda fixed my issue by changing my samba settings. Using Webmin, I was able to go in and change the default settings (as seen here: http://imageshack.us/photo/my-images/521/captureon.png/)

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  • A quick hello to the Western Kentucky .NET User Group

    - by Muljadi Budiman
    A few days back, I got a chance to speak at the Western Kentucky .NET User Group meeting in Murray, Kentucky.  The opportunity came up because the original speaker, Jeff Blankenburg, had another obligation and was thus unable to come to this meeting.  I volunteered to deliver his presentation, which is an overview of MIX10 conference. It was a great experience for me; got to drive around and do a little bit of sight-seeing – can’t say I’ve ever been to Kentucky before, so first trip ever there.  I got to meet the user group’s current lead, Tom Turner and got to chat and discuss about all kinds of stuff with the other members.  Cheers to Matt Gawarecki and Brandon Sharp! The presentation itself mostly covers new features in Visual Studio 2010, which was recently released on April 12 – got to demonstrate Historical Debugging in IntelliTrace, Parallel Stacks, View Call Hierarchy and show some Extensions.  We also covered some of the new functionalities in Silverlight 4 (using webcams, drag & drop support among others) and I got to show off Scott Guthrie’s Windows Phone 7 Twitter app.  Altogether, it was quite a bit to cover in 70 minutes or so, but I think everyone enjoyed it. Jeff provided me with the presentation slides (which I modify a bit) and demo applications; so I’m putting it up here for those that may be interested in downloading them.  Please keep in mind that all the demos were made with VS2010 RC, so there may be slight tweaks to get it to work on the RTM version.

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  • When to use each user research method

    - by user12277104
    There are a lot of user research methods out there, but sometimes we get stuck in a rut, conducting all formative usability testing before coding, or running surveys to gather satisfaction data. I'll be the first to admit that it happens to me, but to get out of a rut, it just takes a minute to look at where I am in the design & development cycle, what kind(s) of data I need, and what methods are available to me. We need reminders, or refreshers, every once in a while. One tool I've found useful is a graphic organizer that I created many years ago. It's been through several revisions, as I've adapted it to the product cycles of the places I've worked, changed my mind about how to categorize it, and added methods that I've used or created over time. I shared a version of this table at the 2012 International UPA conference, and I was contacted by someone yesterday who wanted to use it in a university course on user-center design. I was flattered at the the thought, but embarrassed, because I was sure it needed updating -- that was a year ago, after all. But I opened it today, and really, there's not much I'd change -- sure, I could add some nuance regarding what types of formative testing, such as modality (remote, unmoderated remote, or in-person) or flavor of testing (RITE, RITE-Krug, comparative, performance), but I think it's pretty much ok as is. Click on the image below, to get the full-size PDF. And whether it's entirely "right" or "wrong" isn't the whole value of looking at these methods across the product lifecycle. The real value lies in the reminder that I have options. And what those options are change as the field changes, so while I don't expect this graphic to have an eternal shelf life, it's still ok a year after I last updated it. That said, if you find something missing or out of place, let me know :) 

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  • determine an application's process name on linux (ubuntu)

    - by Jacob
    This is the situation: Working on (the next version of) a Unity quicklist editor, I would like to add a reliable way of "restarting" launcher icons. To do so, I need to remove the icon (editing gsettings) and replace it on the same position. So far no problem. However, if the application in question is running, user will possibly lose data, as the application will quit when it's icon is removed from the launcher. What I need is a reliable way to find an application's process name, to let the editor check in the list of running processes if the application is running, and send a warning message to the user that the icon can not be restarted if the application is running. What i did so far is make the editor look into the desktop file, to read the command, also read the command, stripped from the directory section, and furthermore look into possible remote scripts the desktop file command might refer to, looking for strings starting with "./" Although te method seems to work well with all applications I tested it on, I have the feeling there must be an easier way to cover the problem in an "all in one" way... Is there? also suggestions to catch more exceptional situations are welcome!

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  • elisp compile, add a regexp to error detection

    - by Gauthier
    I am starting with emacs, and don't know much elisp. Nearly nothing, really. I want to use ack as a replacement of grep. These are the instructions I followed to use ack from within emacs: http://www.rooijan.za.net/?q=ack_el Now I don't like the output format that is used in this el file, I would like the output to be that of ack --group. So I changed: (read-string "Ack arguments: " "-i" nil "-i" nil) to: (read-string "Ack arguments: " "-i --group" nil "-i --group" nil) So far so good. But this made me lose the ability to click-press_enter on the rows of the output buffer. In the original behaviour, compile-mode was used to be able to jump to the selected line. I figured I should add a regexp to the ack-mode. The ack-mode is defined like this: (define-compilation-mode ack-mode "Ack" "Specialization of compilation-mode for use with ack." nil) and I want to add the regexp [0-9]+: to be detected as an error too, since it is what every row of the output bugger includes (line number). I've tried to modify the define-compilation-modeabove to add the regexp, but I failed miserably. How can I make the output buffer of ack let me click on its rows? --- EDIT, I tried also: --- (defvar ack-regexp-alist '(("[0-9]+:" 2 3)) "Alist that specifies how to match rows in ack output.") (setq compilation-error-regexp-alist (append compilation-error-regexp-alist ack-regexp-alist)) I stole that somewhere and tried to adapt to my needs. No luck.

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  • Create a Bootable Ubuntu 9.10 USB Flash Drive

    - by Trevor Bekolay
    The Ubuntu Live CD isn’t just useful for trying out Ubuntu before you install it, you can also use it to maintain and repair your Windows PC. Even if you have no intention of installing Linux, every Windows user should have a bootable Ubuntu USB drive on hand in case something goes wrong in Windows. Creating a bootable USB flash drive is surprisingly easy with a small self-contained application called UNetbootin. It will even download Ubuntu for you! Note: Ubuntu will take up approximately 700 MB on your flash drive, so choose a flash drive with at least 1 GB of free space, formatted as FAT32. This process should not remove any existing files on the flash drive, but to be safe you should backup the files on your flash drive. Put Ubuntu on your flash drive UNetbootin doesn’t require installation; just download the application and run it. Select Ubuntu from the Distribution drop-down box, then 9.10_Live from the Version drop-down box. If you have a 64-bit machine, then select 9.10_Live_x64 for the Version. At the bottom of the screen, select the drive letter that corresponds to the USB drive that you want to put Ubuntu on. If you select USB Drive in the Type drop-down box, the only drive letters available will be USB flash drives. Click OK and UNetbootin will start doing its thing. First it will download the Ubuntu Live CD. Then, it will copy the files from the Ubuntu Live CD to your flash drive. The amount of time it takes will vary depending on your Internet speed, an when it’s done, click on Exit. You’re not planning on installing Ubuntu right now, so there’s no need to reboot. If you look at the USB drive now, you should see a bunch of new files and folders. If you had files on the drive before, they should still be present. You’re now ready to boot your computer into Ubuntu 9.10! How to boot into Ubuntu When the time comes that you have to boot into Ubuntu, or if you just want to test and make sure that your flash drive works properly, you will have to set your computer to boot off of the flash drive. The steps to do this will vary depending on your BIOS – which varies depending on your motherboard. To get detailed instructions on changing how your computer boots, search for your motherboard’s manual (or your laptop’s manual for a laptop). For general instructions, which will suffice for 99% of you, read on. Find the important keyboard keys When your computer boots up, a bunch of words and numbers flash across the screen, usually to be ignored. This time, you need to scan the boot-up screen for a few key words with some associated keys: Boot menu and Setup. Typically, these will show up at the bottom of the screen. If your BIOS has a Boot Menu, then read on. Otherwise, skip to the Hard: Using Setup section. Easy: Using the Boot Menu If your BIOS offers a Boot Menu, then during the boot-up process, press the button associated with the Boot Menu. In our case, this is ESC. Our example Boot Menu doesn’t have the ability to boot from USB, but your Boot Menu should have some options, such as USB-CDROM, USB-HDD, USB-FLOPPY, and others. Try the options that start with USB until you find one that works. Don’t worry if it doesn’t work – you can just restart and try again. Using the Boot Menu does not change the normal boot order on your system, so the next time you start up your computer it will boot from the hard drive as normal. Hard: Using Setup If your BIOS doesn’t offer a Boot Menu, then you will have to change the boot order in Setup. Note: There are some options in BIOS Setup that can affect the stability of your machine. Take care to only change the boot order options. Press the button associated with Setup. In our case, this is F2. If your BIOS Setup has a Boot tab, then switch to it and change the order such that one of the USB options occurs first. There may be several USB options, such as USB-CDROM, USB-HDD, USB-FLOPPY, and others; try them out to see which one works for you. If your BIOS does not have a boot tab, boot order is commonly found in Advanced CMOS Options. Note that this changes the boot order permanently until you change it back. If you plan on only plugging in a bootable flash drive when you want to boot from it, then you could leave the boot order as it is, but you may find it easier to switch the order back to the previous order when you reboot from Ubuntu. Booting into Ubuntu If you set the right boot option, then you should be greeted with the UNetbootin screen. Press enter to start Ubuntu with the default options, or wait 10 seconds for this to happen automatically. Ubuntu will start loading. It should go straight to the desktop with no need for a username or password. And that’s it! From this live desktop session, you can try out Ubuntu, and even install software that is not included in the live CD. Installed software will only last for the duration of your session – the next time you start up the live CD it will be back to its original state. Download UNetbootin from sourceforge.net Similar Articles Productive Geek Tips Create a Bootable Ubuntu USB Flash Drive the Easy WayReset Your Ubuntu Password Easily from the Live CDHow-To Geek on Lifehacker: Control Your Computer with Shortcuts & Speed Up Vista SetupHow To Setup a USB Flash Drive to Install Windows 7Speed up Your Windows Vista Computer with ReadyBoost TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 PCmover Professional New Stinger from McAfee Helps Remove ‘FakeAlert’ Threats Google Apps Marketplace: Tools & Services For Google Apps Users Get News Quick and Precise With Newser Scan for Viruses in Ubuntu using ClamAV Replace Your Windows Task Manager With System Explorer Create Talking Photos using Fotobabble

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  • Use an Ubuntu Live CD to Securely Wipe Your PC’s Hard Drive

    - by Trevor Bekolay
    Deleting files or quickly formatting a drive isn’t enough for sensitive personal information. We’ll show you how to get rid of it for good using a Ubuntu Live CD. When you delete a file in Windows, Ubuntu, or any other operating system, it doesn’t actually destroy the data stored on your hard drive, it just marks that data as “deleted.” If you overwrite it later, then that data is generally unrecoverable, but if the operating system don’t happen to overwrite it, then your data is still stored on your hard drive, recoverable by anyone who has the right software. By securely delete files or entire hard drives, your data will be gone for good. Note: Modern hard drives are extremely sophisticated, as are the experts who recover data for a living. There is no guarantee that the methods covered in this article will make your data completely unrecoverable; however, they will make your data unrecoverable to the majority of recovery methods, and all methods that are readily available to the general public. Shred individual files Most of the data stored on your hard drive is harmless, and doesn’t reveal anything about you. If there are just a few files that you know you don’t want someone else to see, then the easiest way to get rid of them is a built-in Linux utility called shred. Open a terminal window by clicking on Applications at the top-left of the screen, then expanding the Accessories menu and clicking on Terminal. Navigate to the file that you want to delete using cd to change directories and ls to list the files and folders in the current directory. As an example, we’ve got a file called BankInfo.txt on a Windows NTFS-formatted hard drive. We want to delete it securely, so we’ll call shred by entering the following in the terminal window: shred <file> which is, in our example: shred BankInfo.txt Notice that our BankInfo.txt file still exists, even though we’ve shredded it. A quick look at the contents of BankInfo.txt make it obvious that the file has indeed been securely overwritten. We can use some command-line arguments to make shred delete the file from the hard drive as well. We can also be extra-careful about the shredding process by upping the number of times shred overwrites the original file. To do this, in the terminal, type in: shred –remove –iterations=<num> <file> By default, shred overwrites the file 25 times. We’ll double this, giving us the following command: shred –remove –iterations=50 BankInfo.txt BankInfo.txt has now been securely wiped on the physical disk, and also no longer shows up in the directory listing. Repeat this process for any sensitive files on your hard drive! Wipe entire hard drives If you’re disposing of an old hard drive, or giving it to someone else, then you might instead want to wipe your entire hard drive. shred can be invoked on hard drives, but on modern file systems, the shred process may be reversible. We’ll use the program wipe to securely delete all of the data on a hard drive. Unlike shred, wipe is not included in Ubuntu by default, so we have to install it. Open up the Synaptic Package Manager by clicking on System in the top-left corner of the screen, then expanding the Administration folder and clicking on Synaptic Package Manager. wipe is part of the Universe repository, which is not enabled by default. We’ll enable it by clicking on Settings > Repositories in the Synaptic Package Manager window. Check the checkbox next to “Community-maintained Open Source software (universe)”. Click Close. You’ll need to reload Synaptic’s package list. Click on the Reload button in the main Synaptic Package Manager window. Once the package list has been reloaded, the text over the search field will change to “Rebuilding search index”. Wait until it reads “Quick search,” and then type “wipe” into the search field. The wipe package should come up, along with some other packages that perform similar functions. Click on the checkbox to the left of the label “wipe” and select “Mark for Installation”. Click on the Apply button to start the installation process. Click the Apply button on the Summary window that pops up. Once the installation is done, click the Close button and close the Synaptic Package Manager window. Open a terminal window by clicking on Applications in the top-left of the screen, then Accessories > Terminal. You need to figure our the correct hard drive to wipe. If you wipe the wrong hard drive, that data will not be recoverable, so exercise caution! In the terminal window, type in: sudo fdisk -l A list of your hard drives will show up. A few factors will help you identify the right hard drive. One is the file system, found in the System column of  the list – Windows hard drives are usually formatted as NTFS (which shows up as HPFS/NTFS). Another good identifier is the size of the hard drive, which appears after its identifier (highlighted in the following screenshot). In our case, the hard drive we want to wipe is only around 1 GB large, and is formatted as NTFS. We make a note of the label found under the the Device column heading. If you have multiple partitions on this hard drive, then there will be more than one device in this list. The wipe developers recommend wiping each partition separately. To start the wiping process, type the following into the terminal: sudo wipe <device label> In our case, this is: sudo wipe /dev/sda1 Again, exercise caution – this is the point of no return! Your hard drive will be completely wiped. It may take some time to complete, depending on the size of the drive you’re wiping. Conclusion If you have sensitive information on your hard drive – and chances are you probably do – then it’s a good idea to securely delete sensitive files before you give away or dispose of your hard drive. The most secure way to delete your data is with a few swings of a hammer, but shred and wipe from a Ubuntu Live CD is a good alternative! Similar Articles Productive Geek Tips Reset Your Ubuntu Password Easily from the Live CDScan a Windows PC for Viruses from a Ubuntu Live CDRecover Deleted Files on an NTFS Hard Drive from a Ubuntu Live CDCreate a Bootable Ubuntu 9.10 USB Flash DriveCreate a Bootable Ubuntu USB Flash Drive the Easy Way TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Office 2010 Product Guides Google Maps Place marks – Pizza, Guns or Strip Clubs Monitor Applications With Kiwi LocPDF is a Visual PDF Search Tool Download Free iPad Wallpapers at iPad Decor Get Your Delicious Bookmarks In Firefox’s Awesome Bar

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  • Error in running script [closed]

    - by SWEngineer
    I'm trying to run heathusf_v1.1.0.tar.gz found here I installed tcsh to make build_heathusf work. But, when I run ./build_heathusf, I get the following (I'm running that on a Fedora Linux system from Terminal): $ ./build_heathusf Compiling programs to build a library of image processing functions. convexpolyscan.c: In function ‘cdelete’: convexpolyscan.c:346:5: warning: incompatible implicit declaration of built-in function ‘bcopy’ [enabled by default] myalloc.c: In function ‘mycalloc’: myalloc.c:68:16: error: invalid storage class for function ‘store_link’ myalloc.c: In function ‘mymalloc’: myalloc.c:101:16: error: invalid storage class for function ‘store_link’ myalloc.c: In function ‘myfree’: myalloc.c:129:27: error: invalid storage class for function ‘find_link’ myalloc.c:131:12: warning: assignment makes pointer from integer without a cast [enabled by default] myalloc.c: At top level: myalloc.c:150:13: warning: conflicting types for ‘store_link’ [enabled by default] myalloc.c:150:13: error: static declaration of ‘store_link’ follows non-static declaration myalloc.c:91:4: note: previous implicit declaration of ‘store_link’ was here myalloc.c:164:24: error: conflicting types for ‘find_link’ myalloc.c:131:14: note: previous implicit declaration of ‘find_link’ was here Building the mammogram resizing program. gcc -O2 -I. -I../common mkimage.o -o mkimage -L../common -lmammo -lm ../common/libmammo.a(aggregate.o): In function `aggregate': aggregate.c:(.text+0x7fa): undefined reference to `mycalloc' aggregate.c:(.text+0x81c): undefined reference to `mycalloc' aggregate.c:(.text+0x868): undefined reference to `mycalloc' ../common/libmammo.a(aggregate.o): In function `aggregate_median': aggregate.c:(.text+0xbc5): undefined reference to `mymalloc' aggregate.c:(.text+0xbfb): undefined reference to `mycalloc' aggregate.c:(.text+0xc3c): undefined reference to `mycalloc' ../common/libmammo.a(aggregate.o): In function `aggregate': aggregate.c:(.text+0x9b5): undefined reference to `myfree' ../common/libmammo.a(aggregate.o): In function `aggregate_median': aggregate.c:(.text+0xd85): undefined reference to `myfree' ../common/libmammo.a(optical_density.o): In function `linear_optical_density': optical_density.c:(.text+0x29e): undefined reference to `mymalloc' optical_density.c:(.text+0x342): undefined reference to `mycalloc' optical_density.c:(.text+0x383): undefined reference to `mycalloc' ../common/libmammo.a(optical_density.o): In function `log10_optical_density': optical_density.c:(.text+0x693): undefined reference to `mymalloc' optical_density.c:(.text+0x74f): undefined reference to `mycalloc' optical_density.c:(.text+0x790): undefined reference to `mycalloc' ../common/libmammo.a(optical_density.o): In function `map_with_ushort_lut': optical_density.c:(.text+0xb2e): undefined reference to `mymalloc' optical_density.c:(.text+0xb87): undefined reference to `mycalloc' optical_density.c:(.text+0xbc6): undefined reference to `mycalloc' ../common/libmammo.a(optical_density.o): In function `linear_optical_density': optical_density.c:(.text+0x4d9): undefined reference to `myfree' ../common/libmammo.a(optical_density.o): In function `log10_optical_density': optical_density.c:(.text+0x8f1): undefined reference to `myfree' ../common/libmammo.a(optical_density.o): In function `map_with_ushort_lut': optical_density.c:(.text+0xd0d): undefined reference to `myfree' ../common/libmammo.a(virtual_image.o): In function `deallocate_cached_image': virtual_image.c:(.text+0x3dc6): undefined reference to `myfree' virtual_image.c:(.text+0x3dd7): undefined reference to `myfree' ../common/libmammo.a(virtual_image.o):virtual_image.c:(.text+0x3de5): more undefined references to `myfree' follow ../common/libmammo.a(virtual_image.o): In function `allocate_cached_image': virtual_image.c:(.text+0x4233): undefined reference to `mycalloc' virtual_image.c:(.text+0x4253): undefined reference to `mymalloc' virtual_image.c:(.text+0x4275): undefined reference to `mycalloc' virtual_image.c:(.text+0x42e7): undefined reference to `mycalloc' virtual_image.c:(.text+0x44f9): undefined reference to `mycalloc' virtual_image.c:(.text+0x47a9): undefined reference to `mycalloc' virtual_image.c:(.text+0x4a45): undefined reference to `mycalloc' virtual_image.c:(.text+0x4af4): undefined reference to `myfree' collect2: error: ld returned 1 exit status make: *** [mkimage] Error 1 Building the breast segmentation program. gcc -O2 -I. -I../common breastsegment.o segment.o -o breastsegment -L../common -lmammo -lm breastsegment.o: In function `render_segmentation_sketch': breastsegment.c:(.text+0x43): undefined reference to `mycalloc' breastsegment.c:(.text+0x58): undefined reference to `mycalloc' breastsegment.c:(.text+0x12f): undefined reference to `mycalloc' breastsegment.c:(.text+0x1b9): undefined reference to `myfree' breastsegment.c:(.text+0x1c6): undefined reference to `myfree' breastsegment.c:(.text+0x1e1): undefined reference to `myfree' segment.o: In function `find_center': segment.c:(.text+0x53): undefined reference to `mycalloc' segment.c:(.text+0x71): undefined reference to `mycalloc' segment.c:(.text+0x387): undefined reference to `myfree' segment.o: In function `bordercode': segment.c:(.text+0x4ac): undefined reference to `mycalloc' segment.c:(.text+0x546): undefined reference to `mycalloc' segment.c:(.text+0x651): undefined reference to `mycalloc' segment.c:(.text+0x691): undefined reference to `myfree' segment.o: In function `estimate_tissue_image': segment.c:(.text+0x10d4): undefined reference to `mycalloc' segment.c:(.text+0x14da): undefined reference to `mycalloc' segment.c:(.text+0x1698): undefined reference to `mycalloc' segment.c:(.text+0x1834): undefined reference to `mycalloc' segment.c:(.text+0x1850): undefined reference to `mycalloc' segment.o:segment.c:(.text+0x186a): more undefined references to `mycalloc' follow segment.o: In function `estimate_tissue_image': segment.c:(.text+0x1bbc): undefined reference to `myfree' segment.c:(.text+0x1c4a): undefined reference to `mycalloc' segment.c:(.text+0x1c7c): undefined reference to `mycalloc' segment.c:(.text+0x1d8e): undefined reference to `myfree' segment.c:(.text+0x1d9b): undefined reference to `myfree' segment.c:(.text+0x1da8): undefined reference to `myfree' segment.c:(.text+0x1dba): undefined reference to `myfree' segment.c:(.text+0x1dc9): undefined reference to `myfree' segment.o:segment.c:(.text+0x1dd8): more undefined references to `myfree' follow segment.o: In function `estimate_tissue_image': segment.c:(.text+0x20bf): undefined reference to `mycalloc' segment.o: In function `segment_breast': segment.c:(.text+0x24cd): undefined reference to `mycalloc' segment.o: In function `find_center': segment.c:(.text+0x3a4): undefined reference to `myfree' segment.o: In function `bordercode': segment.c:(.text+0x6ac): undefined reference to `myfree' ../common/libmammo.a(aggregate.o): In function `aggregate': aggregate.c:(.text+0x7fa): undefined reference to `mycalloc' aggregate.c:(.text+0x81c): undefined reference to `mycalloc' aggregate.c:(.text+0x868): undefined reference to `mycalloc' ../common/libmammo.a(aggregate.o): In function `aggregate_median': aggregate.c:(.text+0xbc5): undefined reference to `mymalloc' aggregate.c:(.text+0xbfb): undefined reference to `mycalloc' aggregate.c:(.text+0xc3c): undefined reference to `mycalloc' ../common/libmammo.a(aggregate.o): In function `aggregate': aggregate.c:(.text+0x9b5): undefined reference to `myfree' ../common/libmammo.a(aggregate.o): In function `aggregate_median': aggregate.c:(.text+0xd85): undefined reference to `myfree' ../common/libmammo.a(cc_label.o): In function `cc_label': cc_label.c:(.text+0x20c): undefined reference to `mycalloc' cc_label.c:(.text+0x6c2): undefined reference to `mycalloc' cc_label.c:(.text+0xbaa): undefined reference to `myfree' ../common/libmammo.a(cc_label.o): In function `cc_label_0bkgd': cc_label.c:(.text+0xe17): undefined reference to `mycalloc' cc_label.c:(.text+0x12d7): undefined reference to `mycalloc' cc_label.c:(.text+0x17e7): undefined reference to `myfree' ../common/libmammo.a(cc_label.o): In function `cc_relabel_by_intensity': cc_label.c:(.text+0x18c5): undefined reference to `mycalloc' ../common/libmammo.a(cc_label.o): In function `cc_label_4connect': cc_label.c:(.text+0x1cf0): undefined reference to `mycalloc' cc_label.c:(.text+0x2195): undefined reference to `mycalloc' cc_label.c:(.text+0x26a4): undefined reference to `myfree' ../common/libmammo.a(cc_label.o): In function `cc_relabel_by_intensity': cc_label.c:(.text+0x1b06): undefined reference to `myfree' ../common/libmammo.a(convexpolyscan.o): In function `polyscan_coords': convexpolyscan.c:(.text+0x6f0): undefined reference to `mycalloc' convexpolyscan.c:(.text+0x75f): undefined reference to `mycalloc' convexpolyscan.c:(.text+0x7ab): undefined reference to `myfree' convexpolyscan.c:(.text+0x7b8): undefined reference to `myfree' ../common/libmammo.a(convexpolyscan.o): In function `polyscan_poly_cacheim': convexpolyscan.c:(.text+0x805): undefined reference to `mycalloc' convexpolyscan.c:(.text+0x894): undefined reference to `myfree' ../common/libmammo.a(mikesfileio.o): In function `read_segmentation_file': mikesfileio.c:(.text+0x1e9): undefined reference to `mycalloc' mikesfileio.c:(.text+0x205): undefined reference to `mycalloc' ../common/libmammo.a(optical_density.o): In function `linear_optical_density': optical_density.c:(.text+0x29e): undefined reference to `mymalloc' optical_density.c:(.text+0x342): undefined reference to `mycalloc' optical_density.c:(.text+0x383): undefined reference to `mycalloc' ../common/libmammo.a(optical_density.o): In function `log10_optical_density': optical_density.c:(.text+0x693): undefined reference to `mymalloc' optical_density.c:(.text+0x74f): undefined reference to `mycalloc' optical_density.c:(.text+0x790): undefined reference to `mycalloc' ../common/libmammo.a(optical_density.o): In function `map_with_ushort_lut': optical_density.c:(.text+0xb2e): undefined reference to `mymalloc' optical_density.c:(.text+0xb87): undefined reference to `mycalloc' optical_density.c:(.text+0xbc6): undefined reference to `mycalloc' ../common/libmammo.a(optical_density.o): In function `linear_optical_density': optical_density.c:(.text+0x4d9): undefined reference to `myfree' ../common/libmammo.a(optical_density.o): In function `log10_optical_density': optical_density.c:(.text+0x8f1): undefined reference to `myfree' ../common/libmammo.a(optical_density.o): In function `map_with_ushort_lut': optical_density.c:(.text+0xd0d): undefined reference to `myfree' ../common/libmammo.a(virtual_image.o): In function `deallocate_cached_image': virtual_image.c:(.text+0x3dc6): undefined reference to `myfree' virtual_image.c:(.text+0x3dd7): undefined reference to `myfree' ../common/libmammo.a(virtual_image.o):virtual_image.c:(.text+0x3de5): more undefined references to `myfree' follow ../common/libmammo.a(virtual_image.o): In function `allocate_cached_image': virtual_image.c:(.text+0x4233): undefined reference to `mycalloc' virtual_image.c:(.text+0x4253): undefined reference to `mymalloc' virtual_image.c:(.text+0x4275): undefined reference to `mycalloc' virtual_image.c:(.text+0x42e7): undefined reference to `mycalloc' virtual_image.c:(.text+0x44f9): undefined reference to `mycalloc' virtual_image.c:(.text+0x47a9): undefined reference to `mycalloc' virtual_image.c:(.text+0x4a45): undefined reference to `mycalloc' virtual_image.c:(.text+0x4af4): undefined reference to `myfree' collect2: error: ld returned 1 exit status make: *** [breastsegment] Error 1 Building the mass feature generation program. gcc -O2 -I. -I../common afumfeature.o -o afumfeature -L../common -lmammo -lm afumfeature.o: In function `afum_process': afumfeature.c:(.text+0xd80): undefined reference to `mycalloc' afumfeature.c:(.text+0xd9c): undefined reference to `mycalloc' afumfeature.c:(.text+0xe80): undefined reference to `mycalloc' afumfeature.c:(.text+0x11f8): undefined reference to `myfree' afumfeature.c:(.text+0x1207): undefined reference to `myfree' afumfeature.c:(.text+0x1214): undefined reference to `myfree' ../common/libmammo.a(aggregate.o): In function `aggregate': aggregate.c:(.text+0x7fa): undefined reference to `mycalloc' aggregate.c:(.text+0x81c): undefined reference to `mycalloc' aggregate.c:(.text+0x868): undefined reference to `mycalloc' ../common/libmammo.a(aggregate.o): In function `aggregate_median': aggregate.c:(.text+0xbc5): undefined reference to `mymalloc' aggregate.c:(.text+0xbfb): undefined reference to `mycalloc' aggregate.c:(.text+0xc3c): undefined reference to `mycalloc' ../common/libmammo.a(aggregate.o): In function `aggregate': aggregate.c:(.text+0x9b5): undefined reference to `myfree' ../common/libmammo.a(aggregate.o): In function `aggregate_median': aggregate.c:(.text+0xd85): undefined reference to `myfree' ../common/libmammo.a(convexpolyscan.o): In function `polyscan_coords': convexpolyscan.c:(.text+0x6f0): undefined reference to `mycalloc' convexpolyscan.c:(.text+0x75f): undefined reference to `mycalloc' convexpolyscan.c:(.text+0x7ab): undefined reference to `myfree' convexpolyscan.c:(.text+0x7b8): undefined reference to `myfree' ../common/libmammo.a(convexpolyscan.o): In function `polyscan_poly_cacheim': convexpolyscan.c:(.text+0x805): undefined reference to `mycalloc' convexpolyscan.c:(.text+0x894): undefined reference to `myfree' ../common/libmammo.a(mikesfileio.o): In function `read_segmentation_file': mikesfileio.c:(.text+0x1e9): undefined reference to `mycalloc' mikesfileio.c:(.text+0x205): undefined reference to `mycalloc' ../common/libmammo.a(optical_density.o): In function `linear_optical_density': optical_density.c:(.text+0x29e): undefined reference to `mymalloc' optical_density.c:(.text+0x342): undefined reference to `mycalloc' optical_density.c:(.text+0x383): undefined reference to `mycalloc' ../common/libmammo.a(optical_density.o): In function `log10_optical_density': optical_density.c:(.text+0x693): undefined reference to `mymalloc' optical_density.c:(.text+0x74f): undefined reference to `mycalloc' optical_density.c:(.text+0x790): undefined reference to `mycalloc' ../common/libmammo.a(optical_density.o): In function `map_with_ushort_lut': optical_density.c:(.text+0xb2e): undefined reference to `mymalloc' optical_density.c:(.text+0xb87): undefined reference to `mycalloc' optical_density.c:(.text+0xbc6): undefined reference to `mycalloc' ../common/libmammo.a(optical_density.o): In function `linear_optical_density': optical_density.c:(.text+0x4d9): undefined reference to `myfree' ../common/libmammo.a(optical_density.o): In function `log10_optical_density': optical_density.c:(.text+0x8f1): undefined reference to `myfree' ../common/libmammo.a(optical_density.o): In function `map_with_ushort_lut': optical_density.c:(.text+0xd0d): undefined reference to `myfree' ../common/libmammo.a(virtual_image.o): In function `deallocate_cached_image': virtual_image.c:(.text+0x3dc6): undefined reference to `myfree' virtual_image.c:(.text+0x3dd7): undefined reference to `myfree' ../common/libmammo.a(virtual_image.o):virtual_image.c:(.text+0x3de5): more undefined references to `myfree' follow ../common/libmammo.a(virtual_image.o): In function `allocate_cached_image': virtual_image.c:(.text+0x4233): undefined reference to `mycalloc' virtual_image.c:(.text+0x4253): undefined reference to `mymalloc' virtual_image.c:(.text+0x4275): undefined reference to `mycalloc' virtual_image.c:(.text+0x42e7): undefined reference to `mycalloc' virtual_image.c:(.text+0x44f9): undefined reference to `mycalloc' virtual_image.c:(.text+0x47a9): undefined reference to `mycalloc' virtual_image.c:(.text+0x4a45): undefined reference to `mycalloc' virtual_image.c:(.text+0x4af4): undefined reference to `myfree' collect2: error: ld returned 1 exit status make: *** [afumfeature] Error 1 Building the mass detection program. make: Nothing to be done for `all'. Building the performance evaluation program. gcc -O2 -I. -I../common DDSMeval.o polyscan.o -o DDSMeval -L../common -lmammo -lm ../common/libmammo.a(mikesfileio.o): In function `read_segmentation_file': mikesfileio.c:(.text+0x1e9): undefined reference to `mycalloc' mikesfileio.c:(.text+0x205): undefined reference to `mycalloc' collect2: error: ld returned 1 exit status make: *** [DDSMeval] Error 1 Building the template creation program. gcc -O2 -I. -I../common mktemplate.o polyscan.o -o mktemplate -L../common -lmammo -lm Building the drawimage program. gcc -O2 -I. -I../common drawimage.o -o drawimage -L../common -lmammo -lm ../common/libmammo.a(mikesfileio.o): In function `read_segmentation_file': mikesfileio.c:(.text+0x1e9): undefined reference to `mycalloc' mikesfileio.c:(.text+0x205): undefined reference to `mycalloc' collect2: error: ld returned 1 exit status make: *** [drawimage] Error 1 Building the compression/decompression program jpeg. gcc -O2 -DSYSV -DNOTRUNCATE -c lexer.c lexer.c:41:1: error: initializer element is not constant lexer.c:41:1: error: (near initialization for ‘yyin’) lexer.c:41:1: error: initializer element is not constant lexer.c:41:1: error: (near initialization for ‘yyout’) lexer.c: In function ‘initparser’: lexer.c:387:21: warning: incompatible implicit declaration of built-in function ‘strlen’ [enabled by default] lexer.c: In function ‘MakeLink’: lexer.c:443:16: warning: incompatible implicit declaration of built-in function ‘malloc’ [enabled by default] lexer.c:447:7: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default] lexer.c:452:7: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default] lexer.c:455:34: warning: incompatible implicit declaration of built-in function ‘calloc’ [enabled by default] lexer.c:458:7: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default] lexer.c:460:3: warning: incompatible implicit declaration of built-in function ‘strcpy’ [enabled by default] lexer.c: In function ‘getstr’: lexer.c:548:26: warning: incompatible implicit declaration of built-in function ‘malloc’ [enabled by default] lexer.c:552:4: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default] lexer.c:557:21: warning: incompatible implicit declaration of built-in function ‘calloc’ [enabled by default] lexer.c:557:28: warning: incompatible implicit declaration of built-in function ‘strlen’ [enabled by default] lexer.c:561:7: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default] lexer.c: In function ‘parser’: lexer.c:794:21: warning: incompatible implicit declaration of built-in function ‘calloc’ [enabled by default] lexer.c:798:8: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default] lexer.c:1074:21: warning: incompatible implicit declaration of built-in function ‘calloc’ [enabled by default] lexer.c:1078:8: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default] lexer.c:1116:21: warning: incompatible implicit declaration of built-in function ‘calloc’ [enabled by default] lexer.c:1120:8: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default] lexer.c:1154:25: warning: incompatible implicit declaration of built-in function ‘calloc’ [enabled by default] lexer.c:1158:5: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default] lexer.c:1190:5: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default] lexer.c:1247:25: warning: incompatible implicit declaration of built-in function ‘calloc’ [enabled by default] lexer.c:1251:5: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default] lexer.c:1283:5: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default] lexer.c: In function ‘yylook’: lexer.c:1867:9: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] lexer.c:1867:20: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] lexer.c:1877:12: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] lexer.c:1877:23: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast] make: *** [lexer.o] Error 1

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  • Interview with Lenz Grimmer about MySQL Connect

    - by Keith Larson
    Keith Larson: Thank you for allowing me to do this interview with you.  I have been talking with a few different Oracle ACEs   about the MySQL Connect Conference. I figured the MySQL community might be missing you as well. You have been very busy with Oracle Linux but I know you still have an eye on the MySQL Community. How have things been?Lenz Grimmer: Thanks for including me in this series of interviews, I feel honored! I've read the other interviews, and really liked them. I still try to follow what's going on over in the MySQL community and it's good to see that many of the familiar faces are still around. Over the course of the 9 years that I was involved with MySQL, many colleagues and contacts turned into good friends and we still maintain close relationships.It's been almost 1.5 years ago that I moved into my new role here in the Linux team at Oracle, and I really enjoy working on a Linux distribution again (I worked for SUSE before I joined MySQL AB in 2002). I'm still learning a lot - Linux in the data center has greatly evolved in so many ways and there are a lot of new and exciting technologies to explore. Keith Larson: What were your thoughts when you heard that Oracle was going to deliver the MySQL Connect conference to the MySQL Community?Lenz Grimmer: I think it's testament to the fact that Oracle deeply cares about MySQL, despite what many skeptics may say. What started as "MySQL Sunday" two years ago has now evolved into a full-blown sub-conference, with 80 sessions at one of the largest corporate IT events in the world. I find this quite telling, not many products at Oracle enjoy this level of exposure! So it certainly makes me feel proud to see how far MySQL has come. Keith Larson: Have you had a chance to look over the sessions? What are your thoughts on them?Lenz Grimmer: I did indeed look at the final schedule.The content committee did a great job with selecting these sessions. I'm glad to see that the content selection was influenced by involving well-known and respected members of the MySQL community. The sessions cover a broad range of topics and technologies, both covering established topics as well as recent developments. Keith Larson: When you get a chance, what sessions do you plan on attending?Lenz Grimmer: I will actually be manning the Oracle booth in the exhibition area on one of these days, so I'm not sure if I'll have a lot of time attending sessions. But if I do, I'd love to see the keynotes and catch some of the sessions that talk about recent developments and new features in MySQL, High Availability and Clustering . Quite a lot has happened and it's hard to keep up with this constant flow of new MySQL releases.In particular, the following sessions caught my attention: MySQL Connect Keynote: The State of the Dolphin Evaluating MySQL High-Availability Alternatives CERN’s MySQL “as a Service” Deployment with Oracle VM: Empowering Users MySQL 5.6 Replication: Taking Scalability and High Availability to the Next Level What’s New in MySQL Server 5.6? MySQL Security: Past and Present MySQL at Twitter: Development and Deployment MySQL Community BOF MySQL Connect Keynote: MySQL Perspectives Keith Larson: So I will ask you just like I have asked the others I have interviewed, any tips that you would give to people for handling the long hours at conferences?Lenz Grimmer: Wear comfortable shoes and make sure to drink a lot! Also prepare a plan of the sessions you would like to attend beforehand and familiarize yourself with the venue, so you can get to the next talk in time without scrambling to find the location. The good thing about piggybacking on such a large conference like Oracle OpenWorld is that you benefit from the whole infrastructure. For example, there is a nice schedule builder that helps you to keep track of your sessions of interest. Other than that, bring enough business cards and talk to people, build up your network among your peers and other MySQL professionals! Keith Larson: What features of the MySQL 5.6 release do you look forward to the most ?Lenz Grimmer: There has been solid progress in so many areas like the InnoDB Storage Engine, the Optimizer, Replication or Performance Schema, it's hard for me to really highlight anything in particular. All in all, MySQL 5.6 sounds like a very promising release. I'm confident it will follow the tradition that Oracle already established with MySQL 5.5, which received a lot of praise even from very critical members of the MySQL community. If I had to name a single feature, I'm particularly and personally happy that the precise GIS functions have finally made it into a GA release - that was long overdue. Keith Larson:  In your opinion what is the best reason for someone to attend this event?Lenz Grimmer: This conference is an excellent opportunity to get in touch with the key people in the MySQL community and ecosystem and to get facts and information from the domain experts and developers that work on MySQL. The broad range of topics should attract people from a variety of roles and relations to MySQL, beginning with Developers and DBAs, to CIOs considering MySQL as a viable solution for their requirements. Keith Larson: You will be attending MySQL Connect and have some Oracle Linux Demos, do you see a growing demand for MySQL on Oracle Linux ?Lenz Grimmer: Yes! Oracle Linux is our recommended Linux distribution and we have a good relationship to the MySQL engineering group. They use Oracle Linux as a base Linux platform for development and QA, so we make sure that MySQL and Oracle Linux are well tested together. Setting up a MySQL server on Oracle Linux can be done very quickly, and many customers recognize the benefits of using them both in combination.Because Oracle Linux is available for free (including free bug fixes and errata), it's an ideal choice for running MySQL in your data center. You can run the same Linux distribution on both your development/staging systems as well as on the production machines, you decide which of these should be covered by a support subscription and at which level of support. This gives you flexibility and provides some really attractive cost-saving opportunities. Keith Larson: Since I am a Linux user and fan, what is on the horizon for  Oracle Linux?Lenz Grimmer: We're working hard on broadening the ecosystem around Oracle Linux, building up partnerships with ISVs and IHVs to certify Oracle Linux as a fully supported platform for their products. We also continue to collaborate closely with the Linux kernel community on various projects, to make sure that Linux scales and performs well on large systems and meets the demands of today's data centers. These improvements and enhancements will then rolled into the Unbreakable Enterprise Kernel, which is the key ingredient that sets Oracle Linux apart from other distributions. We also have a number of ongoing projects which are making good progress, and I'm sure you'll hear more about this at the upcoming OpenWorld conference :) Keith Larson: What is something that more people should be aware of when it comes to Oracle Linux and MySQL ?Lenz Grimmer: Many people assume that Oracle Linux is just tuned for Oracle products, such as the Oracle Database or our Engineered Systems. While it's of course true that we do a lot of testing and optimization for these workloads, Oracle Linux is and will remain a general-purpose Linux distribution that is a very good foundation for setting up a LAMP-Stack, for example. We also provide MySQL RPM packages for Oracle Linux, so you can easily stay up to date if you need something newer than what's included in the stock distribution.One more thing that is really unique to Oracle Linux is Ksplice, which allows you to apply security patches to the running Linux kernel, without having to reboot. This ensures that your MySQL database server keeps up and running and is not affected by any downtime. Keith Larson: What else would you like to add ?Lenz Grimmer: Thanks again for getting in touch with me, I appreciated the opportunity. I'm looking forward to MySQL Connect and Oracle OpenWorld and to meet you and many other people from the MySQL community that I haven't seen for quite some time! Keith Larson:  Thank you Lenz!

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  • Scaling-out Your Services by Message Bus based WCF Transport Extension &ndash; Part 1 &ndash; Background

    - by Shaun
    Cloud computing gives us more flexibility on the computing resource, we can provision and deploy an application or service with multiple instances over multiple machines. With the increment of the service instances, how to balance the incoming message and workload would become a new challenge. Currently there are two approaches we can use to pass the incoming messages to the service instances, I would like call them dispatcher mode and pulling mode.   Dispatcher Mode The dispatcher mode introduces a role which takes the responsible to find the best service instance to process the request. The image below describes the sharp of this mode. There are four clients communicate with the service through the underlying transportation. For example, if we are using HTTP the clients might be connecting to the same service URL. On the server side there’s a dispatcher listening on this URL and try to retrieve all messages. When a message came in, the dispatcher will find a proper service instance to process it. There are three mechanism to find the instance: Round-robin: Dispatcher will always send the message to the next instance. For example, if the dispatcher sent the message to instance 2, then the next message will be sent to instance 3, regardless if instance 3 is busy or not at that moment. Random: Dispatcher will find a service instance randomly, and same as the round-robin mode it regardless if the instance is busy or not. Sticky: Dispatcher will send all related messages to the same service instance. This approach always being used if the service methods are state-ful or session-ful. But as you can see, all of these approaches are not really load balanced. The clients will send messages at any time, and each message might take different process duration on the server side. This means in some cases, some of the service instances are very busy while others are almost idle. For example, if we were using round-robin mode, it could be happened that most of the simple task messages were passed to instance 1 while the complex ones were sent to instance 3, even though instance 1 should be idle. This brings some problem in our architecture. The first one is that, the response to the clients might be longer than it should be. As it’s shown in the figure above, message 6 and 9 can be processed by instance 1 or instance 2, but in reality they were dispatched to the busy instance 3 since the dispatcher and round-robin mode. Secondly, if there are many requests came from the clients in a very short period, service instances might be filled by tons of pending tasks and some instances might be crashed. Third, if we are using some cloud platform to host our service instances, for example the Windows Azure, the computing resource is billed by service deployment period instead of the actual CPU usage. This means if any service instance is idle it is wasting our money! Last one, the dispatcher would be the bottleneck of our system since all incoming messages must be routed by the dispatcher. If we are using HTTP or TCP as the transport, the dispatcher would be a network load balance. If we wants more capacity, we have to scale-up, or buy a hardware load balance which is very expensive, as well as scaling-out the service instances. Pulling Mode Pulling mode doesn’t need a dispatcher to route the messages. All service instances are listening to the same transport and try to retrieve the next proper message to process if they are idle. Since there is no dispatcher in pulling mode, it requires some features on the transportation. The transportation must support multiple client connection and server listening. HTTP and TCP doesn’t allow multiple clients are listening on the same address and port, so it cannot be used in pulling mode directly. All messages in the transportation must be FIFO, which means the old message must be received before the new one. Message selection would be a plus on the transportation. This means both service and client can specify some selection criteria and just receive some specified kinds of messages. This feature is not mandatory but would be very useful when implementing the request reply and duplex WCF channel modes. Otherwise we must have a memory dictionary to store the reply messages. I will explain more about this in the following articles. Message bus, or the message queue would be best candidate as the transportation when using the pulling mode. First, it allows multiple application to listen on the same queue, and it’s FIFO. Some of the message bus also support the message selection, such as TIBCO EMS, RabbitMQ. Some others provide in memory dictionary which can store the reply messages, for example the Redis. The principle of pulling mode is to let the service instances self-managed. This means each instance will try to retrieve the next pending incoming message if they finished the current task. This gives us more benefit and can solve the problems we met with in the dispatcher mode. The incoming message will be received to the best instance to process, which means this will be very balanced. And it will not happen that some instances are busy while other are idle, since the idle one will retrieve more tasks to make them busy. Since all instances are try their best to be busy we can use less instances than dispatcher mode, which more cost effective. Since there’s no dispatcher in the system, there is no bottleneck. When we introduced more service instances, in dispatcher mode we have to change something to let the dispatcher know the new instances. But in pulling mode since all service instance are self-managed, there no extra change at all. If there are many incoming messages, since the message bus can queue them in the transportation, service instances would not be crashed. All above are the benefits using the pulling mode, but it will introduce some problem as well. The process tracking and debugging become more difficult. Since the service instances are self-managed, we cannot know which instance will process the message. So we need more information to support debug and track. Real-time response may not be supported. All service instances will process the next message after the current one has done, if we have some real-time request this may not be a good solution. Compare with the Pros and Cons above, the pulling mode would a better solution for the distributed system architecture. Because what we need more is the scalability, cost-effect and the self-management.   WCF and WCF Transport Extensibility Windows Communication Foundation (WCF) is a framework for building service-oriented applications. In the .NET world WCF is the best way to implement the service. In this series I’m going to demonstrate how to implement the pulling mode on top of a message bus by extending the WCF. I don’t want to deep into every related field in WCF but will highlight its transport extensibility. When we implemented an RPC foundation there are many aspects we need to deal with, for example the message encoding, encryption, authentication and message sending and receiving. In WCF, each aspect is represented by a channel. A message will be passed through all necessary channels and finally send to the underlying transportation. And on the other side the message will be received from the transport and though the same channels until the business logic. This mode is called “Channel Stack” in WCF, and the last channel in the channel stack must always be a transport channel, which takes the responsible for sending and receiving the messages. As we are going to implement the WCF over message bus and implement the pulling mode scaling-out solution, we need to create our own transport channel so that the client and service can exchange messages over our bus. Before we deep into the transport channel, let’s have a look on the message exchange patterns that WCF defines. Message exchange pattern (MEP) defines how client and service exchange the messages over the transportation. WCF defines 3 basic MEPs which are datagram, Request-Reply and Duplex. Datagram: Also known as one-way, or fire-forgot mode. The message sent from the client to the service, and no need any reply from the service. The client doesn’t care about the message result at all. Request-Reply: Very common used pattern. The client send the request message to the service and wait until the reply message comes from the service. Duplex: The client sent message to the service, when the service processing the message it can callback to the client. When callback the service would be like a client while the client would be like a service. In WCF, each MEP represent some channels associated. MEP Channels Datagram IInputChannel, IOutputChannel Request-Reply IRequestChannel, IReplyChannel Duplex IDuplexChannel And the channels are created by ChannelListener on the server side, and ChannelFactory on the client side. The ChannelListener and ChannelFactory are created by the TransportBindingElement. The TransportBindingElement is created by the Binding, which can be defined as a new binding or from a custom binding. For more information about the transport channel mode, please refer to the MSDN document. The figure below shows the transport channel objects when using the request-reply MEP. And this is the datagram MEP. And this is the duplex MEP. After investigated the WCF transport architecture, channel mode and MEP, we finally identified what we should do to extend our message bus based transport layer. They are: Binding: (Optional) Defines the channel elements in the channel stack and added our transport binding element at the bottom of the stack. But we can use the build-in CustomBinding as well. TransportBindingElement: Defines which MEP is supported in our transport and create the related ChannelListener and ChannelFactory. This also defines the scheme of the endpoint if using this transport. ChannelListener: Create the server side channel based on the MEP it’s. We can have one ChannelListener to create channels for all supported MEPs, or we can have ChannelListener for each MEP. In this series I will use the second approach. ChannelFactory: Create the client side channel based on the MEP it’s. We can have one ChannelFactory to create channels for all supported MEPs, or we can have ChannelFactory for each MEP. In this series I will use the second approach. Channels: Based on the MEPs we want to support, we need to implement the channels accordingly. For example, if we want our transport support Request-Reply mode we should implement IRequestChannel and IReplyChannel. In this series I will implement all 3 MEPs listed above one by one. Scaffold: In order to make our transport extension works we also need to implement some scaffold stuff. For example we need some classes to send and receive message though out message bus. We also need some codes to read and write the WCF message, etc.. These are not necessary but would be very useful in our example.   Message Bus There is only one thing remained before we can begin to implement our scaling-out support WCF transport, which is the message bus. As I mentioned above, the message bus must have some features to fulfill all the WCF MEPs. In my company we will be using TIBCO EMS, which is an enterprise message bus product. And I have said before we can use any message bus production if it’s satisfied with our requests. Here I would like to introduce an interface to separate the message bus from the WCF. This allows us to implement the bus operations by any kinds bus we are going to use. The interface would be like this. 1: public interface IBus : IDisposable 2: { 3: string SendRequest(string message, bool fromClient, string from, string to = null); 4:  5: void SendReply(string message, bool fromClient, string replyTo); 6:  7: BusMessage Receive(bool fromClient, string replyTo); 8: } There are only three methods for the bus interface. Let me explain one by one. The SendRequest method takes the responsible for sending the request message into the bus. The parameters description are: message: The WCF message content. fromClient: Indicates if this message was came from the client. from: The channel ID that this message was sent from. The channel ID will be generated when any kinds of channel was created, which will be explained in the following articles. to: The channel ID that this message should be received. In Request-Reply and Duplex MEP this is necessary since the reply message must be received by the channel which sent the related request message. The SendReply method takes the responsible for sending the reply message. It’s very similar as the previous one but no “from” parameter. This is because it’s no need to reply a reply message again in any MEPs. The Receive method takes the responsible for waiting for a incoming message, includes the request message and specified reply message. It returned a BusMessage object, which contains some information about the channel information. The code of the BusMessage class is 1: public class BusMessage 2: { 3: public string MessageID { get; private set; } 4: public string From { get; private set; } 5: public string ReplyTo { get; private set; } 6: public string Content { get; private set; } 7:  8: public BusMessage(string messageId, string fromChannelId, string replyToChannelId, string content) 9: { 10: MessageID = messageId; 11: From = fromChannelId; 12: ReplyTo = replyToChannelId; 13: Content = content; 14: } 15: } Now let’s implement a message bus based on the IBus interface. Since I don’t want you to buy and install the TIBCO EMS or any other message bus products, I will implement an in process memory bus. This bus is only for test and sample purpose. It can only be used if the service and client are in the same process. Very straightforward. 1: public class InProcMessageBus : IBus 2: { 3: private readonly ConcurrentDictionary<Guid, InProcMessageEntity> _queue; 4: private readonly object _lock; 5:  6: public InProcMessageBus() 7: { 8: _queue = new ConcurrentDictionary<Guid, InProcMessageEntity>(); 9: _lock = new object(); 10: } 11:  12: public string SendRequest(string message, bool fromClient, string from, string to = null) 13: { 14: var entity = new InProcMessageEntity(message, fromClient, from, to); 15: _queue.TryAdd(entity.ID, entity); 16: return entity.ID.ToString(); 17: } 18:  19: public void SendReply(string message, bool fromClient, string replyTo) 20: { 21: var entity = new InProcMessageEntity(message, fromClient, null, replyTo); 22: _queue.TryAdd(entity.ID, entity); 23: } 24:  25: public BusMessage Receive(bool fromClient, string replyTo) 26: { 27: InProcMessageEntity e = null; 28: while (true) 29: { 30: lock (_lock) 31: { 32: var entity = _queue 33: .Where(kvp => kvp.Value.FromClient == fromClient && (kvp.Value.To == replyTo || string.IsNullOrWhiteSpace(kvp.Value.To))) 34: .FirstOrDefault(); 35: if (entity.Key != Guid.Empty && entity.Value != null) 36: { 37: _queue.TryRemove(entity.Key, out e); 38: } 39: } 40: if (e == null) 41: { 42: Thread.Sleep(100); 43: } 44: else 45: { 46: return new BusMessage(e.ID.ToString(), e.From, e.To, e.Content); 47: } 48: } 49: } 50:  51: public void Dispose() 52: { 53: } 54: } The InProcMessageBus stores the messages in the objects of InProcMessageEntity, which can take some extra information beside the WCF message itself. 1: public class InProcMessageEntity 2: { 3: public Guid ID { get; set; } 4: public string Content { get; set; } 5: public bool FromClient { get; set; } 6: public string From { get; set; } 7: public string To { get; set; } 8:  9: public InProcMessageEntity() 10: : this(string.Empty, false, string.Empty, string.Empty) 11: { 12: } 13:  14: public InProcMessageEntity(string content, bool fromClient, string from, string to) 15: { 16: ID = Guid.NewGuid(); 17: Content = content; 18: FromClient = fromClient; 19: From = from; 20: To = to; 21: } 22: }   Summary OK, now I have all necessary stuff ready. The next step would be implementing our WCF message bus transport extension. In this post I described two scaling-out approaches on the service side especially if we are using the cloud platform: dispatcher mode and pulling mode. And I compared the Pros and Cons of them. Then I introduced the WCF channel stack, channel mode and the transport extension part, and identified what we should do to create our own WCF transport extension, to let our WCF services using pulling mode based on a message bus. And finally I provided some classes that need to be used in the future posts that working against an in process memory message bus, for the demonstration purpose only. In the next post I will begin to implement the transport extension step by step.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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  • Drop and Give Me 20 Questions

    - by [email protected]
    IOUG Sponsors Boot Camp at Collaborate 10 Feeling flabby and out of shape on topics such as virtualization, SQL development, and security? Want to beef up your skills on Oracle Database 11g Release 2, Oracle on Linux for IBM System z, and Oracle's maximum availability architecture on Linux for IBM System z? If so, it's time for boot camp. The Independent Oracle Users Group (IOUG) is sponsoring its first-ever boot camp for Oracle technology and database professionals at Collaborate 10, April 19 to 21. And yes, as with many boot camps, the IOUG programs will be in a harsh, desert environment--at the Mandalay Bay Convention Center in Las Vegas, Nevada. The one- and two-day programs will cover Oracle technology and a variety of database topics, and they'll be taught by drill instructors, including industry experts as well as Oracle users and staff. You'll get in-depth training. But don't worry. You won't have to suffer through a bad haircut and 20-mile hikes. Are you ready? Was that a "yes, sir"? I can't hear you.

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  • Problem on login: Freeze just before user selection

    - by Diego Garcia
    Hi, I'm using ubuntu 10.10 and when I login it shows my login's wallpaper an appears the window where I select my user without showing it and then gets frozen. No mouse response, no keyboard responde (even if I try to num/caps lock). I tried with safe mode and same thing happens, but in that case it freeze when trying to load some USB stuff, I tought it was my USB headset or my mouse so I disconnected them but doesn't works. Any advice on how to fix this, how to login to try an update or how to post more information?

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  • User Productivity Kit - Powerful Packages (Part 2)

    - by [email protected]
    In my first post on packages I described what a package is and how it can be used. I also started explaining some of the considerations that should be taken into account when determining how to arrange your packages. The first is when the files are interrelated and depend on one another such as an HTML file and it's graphics. A second consideration is how the files are used in your outlines. Let's say you're using a dozen Word doc files. You could place them all in a single package or put each Word doc file in a separate package but what's the right thing to do? There are several factors that will influence your decision. To understand the first, let me explain a function of UPK publishing. Take an outline in UPK that has an attachment (concept, frame link, or hyperlink) that points to a file in a package. When you publish this outline, the publishing engine will determine that there is a link to a file in the package and copy the contents of the package to the publishing destination directory. This is done to ensure that any interrelated files are kept together. For the situation where you have an HTML file with links to number of graphics files, this is a good thing. If, however, the package has a dozen unrelated Word doc files and you link to only one of them, all dozen Word documents will be copied to the publishing destination directory.  Whether or not this is a good thing is dependent on two things. First, are all of the files in the package used in the outline that you're publishing? Take an outline that includes links to all of the Word documents in that dozen document package I described earlier. For this situation, you may choose to keep all the files in a single package for convenience. A second consideration is how your organization leverages reuse in UPK. In this context, I'm referring to the link style of reuse such as when you link to the same topic from multiple UPK outlines and changes to the topic appear in both places. Take an example where you have the earlier mentioned dozen Word document package and an outline with a dozen topics in it. Each topic has an attachment pointing to one of the Word documents in the package (frame link, concept, etc.) If you're only publishing this outline, the single package probably works fine but what if you're reusing one of these topics in another outline? As I explained earlier, linking to one file in the package will result in all files in the package being copied to your published output. In this example, linking to one topic in the first outline will result in all dozen Word documents being copied to the published output. This may result in files in the output that you don't want there for business or size reasons. This is a situation in which you should consider placing each of the Word documents in it's own separate package. With each document in it's own package, that link to a single document will result in only that single package and single Word document being copied to the published output. In my last post I had described that packages are documents in the UPK library. When using the multi-user version of the UPK Developer you can leverage standard library capabilities for managing the files in these packages during the development process - capabilities such as check in / check out, history, etc. When structuring your packages take into consideration how the authors are going to be adding, modifying and deleting files from the packages. A single package is a single document in the UPK library. Like any other document in the library, a single user can check out the package and edit it at a time. If you have a large number of files in a single package and these must be modified by many users, you need to consider whether this will cause problems as multiple users compete to update the same package. If the files don't depend on each other consider placing the files in separate packages to reduce contention. I hope you've enjoyed these two posts on how you can leverage the power of packages in your content. In summary, consider the following when structuring your packages: Is the asset a single, standalone file or a set of files that depend on each other? Will all the files always be used together in a single outline or may only some of the files be needed based on how the content is reused across multiple outlines? Will multiple developers need to update the files in a single package or should you break it into multiple packages to reduce contention when checking out the document? We'd like to hear from you on how you're using packages in your content. Please add your comments below! Thank you and I hope these two posts have given you additional insights into how to use packages in your content and structure them for efficient use. John Zaums Senior Director, Product Development Oracle User Productivity Kit

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  • Where and how to reference composite MVP components?

    - by Lea Hayes
    I am learning about the MVP (Model-View-Presenter) Passive View flavour of MVC. I intend to expose events from view interfaces rather than using the observer pattern to remove explicit coupling with presenter. Context: Windows Forms / Client-Side JavaScript. I am led to believe that the MVP (or indeed MVC in general) pattern can be applied at various levels of a user interface ranging from the main "Window" to an embedded "Text Field". For instance, the model to the text field is probably just a string whereas the model to the "Window" contains application specific view state (like a persons name which resides within the contained text field). Given a more complex scenario: Documentation viewer which contains: TOC navigation pane Document view Search pane Since each of these 4 user interface items are complex and can be reused elsewhere it makes sense to design these using MVP. Given that each of these user interface items comprises of 3 components; which component should be nested? where? who instantiates them? Idea #1 - Embed View inside View from Parent View public class DocumentationViewer : Form, IDocumentationViewerView { public DocumentationViewer() { ... // Unclear as to how model and presenter are injected... TocPane = new TocPaneView(); } protected ITocPaneView TocPane { get; private set; } } Idea #2 - Embed Presenter inside View from Parent View public class DocumentationViewer : Form, IDocumentationViewerView { public DocumentationViewer() { ... // This doesn't seem like view logic... var tocPaneModel = new TocPaneModel(); var tocPaneView = new TocPaneView(); TocPane = new TocPanePresenter(tocPaneModel, tocPaneView); } protected TocPanePresenter TocPane { get; private set; } } Idea #3 - Embed View inside View from Parent Presenter public class DocumentationViewer : Form, IDocumentationViewerView { ... // Part of IDocumentationViewerView: public ITocPaneView TocPane { get; set; } } public class DocumentationViewerPresenter { public DocumentationViewerPresenter(DocumentationViewerModel model, IDocumentationViewerView view) { ... var tocPaneView = new TocPaneView(); var tocPaneModel = new TocPaneModel(model.Toc); var tocPanePresenter = new TocPanePresenter(tocPaneModel, tocPaneView); view.TocPane = tocPaneView; } } Some better idea...

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  • dotnet Cologne 2013 – Vorträge gesucht!

    - by WeigeltRo
    Am 3. Mai 2013 findet im Mediapark Köln die dotnet Cologne 2013 statt. Damit die mittlerweile fünfte Ausgabe dieser Community-Konferenz wieder ein solcher Erfolg wie in den Vorjahren wird, suchen wir (Stefan Lange, Melanie Eibl, Albert Weinert und ich) Sprecher mit interessanten Vorträgen zu Technologien aus dem Microsoft-Umfeld. Dabei wünschen wir uns sowohl Einführungsvorträge in neue Themen als auch die eine oder andere “Level 400 Hardcore-Session” für Spezialisten. Für beides sind passende Räume im Komed vorhanden, das auch in diesem Jahr wieder Veranstaltungsort sein wird. Alle Infos zum Call for Papers gibt es hier. Über die dotnet Cologne Die dotnet Cologne, die 2009 zum ersten Mal stattfand, hat sich im Laufe der Jahre mit mittlerweile 350 Teilnehmern zur größten .NET Community-Konferenz in Deutschland entwickelt. Veranstaltet von den .NET User Groups Bonn-to-Code.Net und .net user group Köln, versteht sich die dotnet Cologne als Konferenz von Entwicklern für Entwickler.

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  • Refactoring a Single Rails Model with large methods & long join queries trying to do everything

    - by Kelseydh
    I have a working Ruby on Rails Model that I suspect is inefficient, hard to maintain, and full of unnecessary SQL join queries. I want to optimize and refactor this Model (Quiz.rb) to comply with Rails best practices, but I'm not sure how I should do it. The Rails app is a game that has Missions with many Stages. Users complete Stages by answering Questions that have correct or incorrect Answers. When a User tries to complete a stage by answering questions, the User gets a Quiz entry with many Attempts. Each Attempt records an Answer submitted for that Question within the Stage. A user completes a stage or mission by getting every Attempt correct, and their progress is tracked by adding a new entry to the UserMission & UserStage join tables. All of these features work, but unfortunately the Quiz.rb Model has been twisted to handle almost all of it exclusively. The callbacks began at 'Quiz.rb', and because I wasn't sure how to leave the Quiz Model during a multi-model update, I resorted to using Rails Console to have the @quiz instance variable via self.some_method do all the heavy lifting to retrieve every data value for the game's business logic; resulting in large extended join queries that "dance" all around the Database schema. The Quiz.rb Model that Smells: class Quiz < ActiveRecord::Base belongs_to :user has_many :attempts, dependent: :destroy before_save :check_answer before_save :update_user_mission_and_stage accepts_nested_attributes_for :attempts, :reject_if => lambda { |a| a[:answer_id].blank? }, :allow_destroy => true #Checks every answer within each quiz, adding +1 for each correct answer #within a stage quiz, and -1 for each incorrect answer def check_answer stage_score = 0 self.attempts.each do |attempt| if attempt.answer.correct? == true stage_score += 1 elsif attempt.answer.correct == false stage_score - 1 end end stage_score end def winner return true end def update_user_mission_and_stage ####### #Step 1: Checks if UserMission exists, finds or creates one. #if no UserMission for the current mission exists, creates a new UserMission if self.user_has_mission? == false @user_mission = UserMission.new(user_id: self.user.id, mission_id: self.current_stage.mission_id, available: true) @user_mission.save else @user_mission = self.find_user_mission end ####### #Step 2: Checks if current UserStage exists, stops if true to prevent duplicate entry if self.user_has_stage? @user_mission.save return true else ####### ##Step 3: if step 2 returns false: ##Initiates UserStage creation instructions #checks for winner (winner actions need to be defined) if they complete last stage of last mission for a given orientation if self.passed? && self.is_last_stage? && self.is_last_mission? create_user_stage_and_update_user_mission self.winner #NOTE: The rest are the same, but specify conditions that are available to add badges or other actions upon those conditions occurring: ##if user completes first stage of a mission elsif self.passed? && self.is_first_stage? && self.is_first_mission? create_user_stage_and_update_user_mission #creates user badge for finishing first stage of first mission self.user.add_badge(5) self.user.activity_logs.create(description: "granted first-stage badge", type_event: "badge", value: "first-stage") #If user completes last stage of a given mission, creates a new UserMission elsif self.passed? && self.is_last_stage? && self.is_first_mission? create_user_stage_and_update_user_mission #creates user badge for finishing first mission self.user.add_badge(6) self.user.activity_logs.create(description: "granted first-mission badge", type_event: "badge", value: "first-mission") elsif self.passed? create_user_stage_and_update_user_mission else self.passed? == false return true end end end #Creates a new UserStage record in the database for a successful Quiz question passing def create_user_stage_and_update_user_mission @nu_stage = @user_mission.user_stages.new(user_id: self.user.id, stage_id: self.current_stage.id) @nu_stage.save @user_mission.save self.user.add_points(50) end #Boolean that defines passing a stage as answering every question in that stage correct def passed? self.check_answer >= self.number_of_questions end #Returns the number of questions asked for that stage's quiz def number_of_questions self.attempts.first.answer.question.stage.questions.count end #Returns the current_stage for the Quiz, routing through 1st attempt in that Quiz def current_stage self.attempts.first.answer.question.stage end #Gives back the position of the stage relative to its mission. def stage_position self.attempts.first.answer.question.stage.position end #will find the user_mission for the current user and stage if it exists def find_user_mission self.user.user_missions.find_by_mission_id(self.current_stage.mission_id) end #Returns true if quiz was for the last stage within that mission #helpful for triggering actions related to a user completing a mission def is_last_stage? self.stage_position == self.current_stage.mission.stages.last.position end #Returns true if quiz was for the first stage within that mission #helpful for triggering actions related to a user completing a mission def is_first_stage? self.stage_position == self.current_stage.mission.stages_ordered.first.position end #Returns true if current user has a UserMission for the current stage def user_has_mission? self.user.missions.ids.include?(self.current_stage.mission.id) end #Returns true if current user has a UserStage for the current stage def user_has_stage? self.user.stages.include?(self.current_stage) end #Returns true if current user is on the last mission based on position within a given orientation def is_first_mission? self.user.missions.first.orientation.missions.by_position.first.position == self.current_stage.mission.position end #Returns true if current user is on the first stage & mission of a given orientation def is_last_mission? self.user.missions.first.orientation.missions.by_position.last.position == self.current_stage.mission.position end end My Question Currently my Rails server takes roughly 500ms to 1 sec to process single @quiz.save action. I am confident that the slowness here is due to sloppy code, not bad Database ERD design. What does a better solution look like? And specifically: Should I use join queries to retrieve values like I did here, or is it better to instantiate new objects within the model instead? Or am I missing a better solution? How should update_user_mission_and_stage be refactored to follow best practices? Relevant Code for Reference: quizzes_controller.rb w/ Controller Route Initiating Callback: class QuizzesController < ApplicationController before_action :find_stage_and_mission before_action :find_orientation before_action :find_question def show end def create @user = current_user @quiz = current_user.quizzes.new(quiz_params) if @quiz.save if @quiz.passed? if @mission.next_mission.nil? && @stage.next_stage.nil? redirect_to root_path, notice: "Congratulations, you have finished the last mission!" elsif @stage.next_stage.nil? redirect_to [@mission.next_mission, @mission.first_stage], notice: "Correct! Time for Mission #{@mission.next_mission.position}", info: "Starting next mission" else redirect_to [@mission, @stage.next_stage], notice: "Answer Correct! You passed the stage!" end else redirect_to [@mission, @stage], alert: "You didn't get every question right, please try again." end else redirect_to [@mission, @stage], alert: "Sorry. We were unable to save your answer. Please contact the admministrator." end @questions = @stage.questions.all end private def find_stage_and_mission @stage = Stage.find(params[:stage_id]) @mission = @stage.mission end def find_question @question = @stage.questions.find_by_id params[:id] end def quiz_params params.require(:quiz).permit(:user_id, :attempt_id, {attempts_attributes: [:id, :quiz_id, :answer_id]}) end def find_orientation @orientation = @mission.orientation @missions = @orientation.missions.by_position end end Overview of Relevant ERD Database Relationships: Mission - Stage - Question - Answer - Attempt <- Quiz <- User Mission - UserMission <- User Stage - UserStage <- User Other Models: Mission.rb class Mission < ActiveRecord::Base belongs_to :orientation has_many :stages has_many :user_missions, dependent: :destroy has_many :users, through: :user_missions #SCOPES scope :by_position, -> {order(position: :asc)} def stages_ordered stages.order(:position) end def next_mission self.orientation.missions.find_by_position(self.position.next) end def first_stage next_mission.stages_ordered.first end end Stage.rb: class Stage < ActiveRecord::Base belongs_to :mission has_many :questions, dependent: :destroy has_many :user_stages, dependent: :destroy has_many :users, through: :user_stages accepts_nested_attributes_for :questions, reject_if: :all_blank, allow_destroy: true def next_stage self.mission.stages.find_by_position(self.position.next) end end Question.rb class Question < ActiveRecord::Base belongs_to :stage has_many :answers, dependent: :destroy accepts_nested_attributes_for :answers, :reject_if => lambda { |a| a[:body].blank? }, :allow_destroy => true end Answer.rb: class Answer < ActiveRecord::Base belongs_to :question has_many :attempts, dependent: :destroy end Attempt.rb: class Attempt < ActiveRecord::Base belongs_to :answer belongs_to :quiz end User.rb: class User < ActiveRecord::Base belongs_to :school has_many :activity_logs has_many :user_missions, dependent: :destroy has_many :missions, through: :user_missions has_many :user_stages, dependent: :destroy has_many :stages, through: :user_stages has_many :orientations, through: :school has_many :quizzes, dependent: :destroy has_many :attempts, through: :quizzes def latest_stage_position self.user_missions.last.user_stages.last.stage.position end end UserMission.rb class UserMission < ActiveRecord::Base belongs_to :user belongs_to :mission has_many :user_stages, dependent: :destroy end UserStage.rb class UserStage < ActiveRecord::Base belongs_to :user belongs_to :stage belongs_to :user_mission end

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  • Must-see sessions at TCUK11

    - by Roger Hart
    Technical Communication UK is probably the best professional conference I've been to. Last year, I spoke there on content strategy, and this year I'll be co-hosting a workshop on embedded user assistance. Obviously, I'd love people to come along to that; but there are some other sessions I'd like to flag up for anybody thinking of attending. Tuesday 20th Sept - workshops This will be my first year at the pre-conference workshop day, and I'm massively glad that our workshop hasn't been scheduled along-side the one I'm really interested in. My picks: It looks like you're embedding user assistance. Would you like help? My colleague Dom and I are presenting this one. It's our paen to Clippy, to the brilliant idea he represented, and the crashing failure he was. Less precociously, we'll be teaching embedded user assistance, Red Gate style. Statistics without maths: acquiring, visualising and interpreting your data This doesn't need to do anything apart from what it says on the tin in order to be gold dust. But given the speakers, I suspect it will. A data-informed approach is a great asset to technical communications, so I'd recommend this session to anybody event faintly interested. The speakers here have a great track record of giving practical, accessible introductions to big topics. Go along. Wednesday 21st Sept - day one There's no real need to recommend the keynote for a conference, but I will just point out that this year it's Google's Patrick Hofmann. That's cool. You know what else is cool: Focus on the user, the rest follows An intro to modelling customer experience. This is a really exciting area for tech comms, and potentially touches on one of my personal hobby-horses: the convergence of technical communication and marketing. It's all part of delivering customer experience, and knowing what your users need lets you help them, sell to them, and delight them. Content strategy year 1: a tale from the trenches It's often been observed that content strategy is great at banging its own drum, but not so hot on compelling case studies. Here you go, folks. This is the presentation I'm most excited about so far. On a mission to communicate! Skype help their users communicate, but how do they communicate with them? I guess we'll find out. Then there's the stuff that I'm not too excited by, but you might just be. The standards geeks and agile freaks can get together in a presentation on the forthcoming ISO standards for agile authoring. Plus, there's a session on VBA for tech comms. I do have one gripe about day 1. The other big UK tech comms conference, UA Europe, have - I think - netted the more interesting presentation from Ellis Pratt. While I have no doubt that his TCUK case study on producing risk assessments will be useful, I'd far rather go to his talk on game theory for tech comms. Hopefully UA Europe will record it. Thursday 22nd Sept - day two Day two has a couple of slots yet to be confirmed. The rumour is that one of them will be the brilliant "Questions and rants" session from last year. I hope so. It's not ranting, but I'll be going to: RTFMobile: beyond stating the obvious Ultan O'Broin is an engaging speaker with a lot to say, and mobile is one of the most interesting and challenging new areas for tech comms. Even if this weren't a research-based presentation from a company with buckets of technology experience, I'd be going. It is, and you should too. Pattern recognition for technical communicators One of the best things about TCUK is the tendency to include sessions that tackle the theoretical and bring them towards the practical. Kai and Chris delivered cracking and well-received talks last year, and I'm looking forward to seeing what they've got for us on some of the conceptual underpinning of technical communication. Developing an interactive non-text learning programme Annoyingly, this clashes with Pattern Recognition, so I hope at least one of the streams is recorded again this year. The idea of communicating complex information without words us fascinating and this sounds like a great example of this year's third stream: "anything but text". For the localization and DITA crowds, there's rich pickings on day two, though I'm not sure how many of those sessions I'm interested in. In the 13:00 - 13:40 slot, there's an interesting clash between Linda Urban on re-use and training content, and a piece on minimalism I'm sorely tempted by. That's my pick of #TCUK11. I'll be doing a round-up blog after the event, and probably talking a bit more about it beforehand. I'm also reliably assured that there are still plenty of tickets.

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  • Please help ubuntu or any other linux os is not booting from cd or usb

    - by Amith
    I will tell you the whole story,one night when i was using KDE on Ubuntu 10.10 Kwin crashed then i shut down the os next day when i booted it the display came completely garbled and i went to safe graphics mode ,it worked and in reinstalled the Nvidia drivers and then restarted .Then immediatly, It said No init found Busybox XX.XX then I thought ill do a fresh install I inserted the ubuntu cd provided to me by Canonical.When i pressed 'try ubuntu without installing' instead of the graphic boot screen i saw.Ubuntu 10.10 in regular text and a progress bar few seconds after that the screen was flooded with error messages first alot of white then red.I then went to my win7 installation and saw a website which told me to find a Ext3 reader and format the ubuntu partition and the swap.I did that and when i restarted. GRUB configuration not found grub> Then it took my win 7 ERD and restored 7's bootloder Xp and 7 were working i put in the livecd again,Same error,Now usin my seven,Please help geeks,Ive even tried Knoppix,Fedora,Debiane.t.c they wont boot and i want to retain my win 7 and winxp partitions,I really miss linux.

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  • How to customize system preferences settings for all users

    - by user3215
    Does anybody know how to apply a customized user settings to other existing or new users?. Something like a customized preferences settings for system wide so that everybody posses those settings and below will explain in clear what I actually ment. On every machine I will install the following: Eclipse Mysql Query Browser and Admin Mysql Workbench Oracle VirtualBox Thunderbird ----------- ----------- ----------- If I install them by apt, this will automatically create shortcuts in Applications but when I build them from source or extract the tar ball, I will have to add New Item at it's relevant place going to System-->Preferences-->Main Menu to make them available as a shortcuts and this settings are applied only for the account I login and perform them. How could I make this preferences settings for complete system wide which applies for all users? or if there is a way to apply a customized user settings to other users will also be ok. Any hint please? Thank you!

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  • Why is my system freezing when I switch users

    - by ZeroDivide
    Hello I've recently upgraded from 13.04 to 13.10 64bit. I'm running AMD graphics with the proprietary drivers. I have two user accounts. Mine(administrator) and my girlfriend's(standard) My girlfriend clicks "switch user" from my lock screen and logs in fine. I then try to click "switch user" from her lock screen and everything goes black. Then the monitor blinks on and off with just a single cursor. I have no way to access the terminal, the system is unresponsive and I have to hit the power button. Even ctrl + alt + f4 or ctrl + alt + t doesn't get me a terminal. When I press the power button on my system, it does start printing out the shutdown sequence on the monitor. Here is my .xsession-errors Script for ibus started at run_im. Script for auto started at run_im. Script for default started at run_im. Here is hers: init: at-spi2-registryd main process ended, respawning init: at-spi2-registryd main process ended, respawning init: at-spi2-registryd main process ended, respawning init: at-spi2-registryd main process ended, respawning init: at-spi2-registryd main process ended, respawning init: at-spi2-registryd main process ended, respawning init: at-spi2-registryd main process ended, respawning init: at-spi2-registryd main process ended, respawning init: at-spi2-registryd main process ended, respawning init: at-spi2-registryd main process ended, respawning init: at-spi2-registryd respawning too fast, stopped init: logrotate main process (4726) killed by TERM signal init: upstart-dbus-session-bridge main process (4865) terminated with status 1 init: gnome-settings-daemon main process (4843) terminated with status 1 init: gnome-session main process (4852) terminated with status 1 init: unity-panel-service main process (4863) killed by KILL signal I found some advice in a forum to look for at-spi2-registryd in my system logs. Perhaps it will be useful. executing this: sudo grep -r at-spi2-registryd /var/log/* produces this: /var/log/lightdm/x-1-greeter.log:** (at-spi2-registryd:4384): WARNING **: Failed to register client: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files /var/log/lightdm/x-1-greeter.log:** (at-spi2-registryd:4384): WARNING **: Unable to register client with session manager /var/log/lightdm/x-2-greeter.log.old:** (at-spi2-registryd:7447): WARNING **: Failed to register client: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files /var/log/lightdm/x-2-greeter.log.old:** (at-spi2-registryd:7447): WARNING **: Unable to register client with session manager /var/log/lightdm/x-0-greeter.log:** (at-spi2-registryd:1378): WARNING **: Failed to register client: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files /var/log/lightdm/x-0-greeter.log:** (at-spi2-registryd:1378): WARNING **: Unable to register client with session manager /var/log/lightdm/x-0-greeter.log.old:** (at-spi2-registryd:1357): WARNING **: Failed to register client: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files /var/log/lightdm/x-0-greeter.log.old:** (at-spi2-registryd:1357): WARNING **: Unable to register client with session manager Any ideas what is going on?

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  • WWW.yoursite.com or HTTP://yoursite.com which one is futureproof?

    - by Sam
    http://yoursite.com www.yoursite.com http://www.yoursite.com yoursite.com Which of these would you choose as your favourite to work with, if you were to make a site for 2011 and beyond, which domainname would you provide to clients, websites linking to you, your letterhead, contact cards. Why one OR other? Which to avoid? Thinking of the following aspects: validity, correctly loading URL audience, most geeks know http://, most seniors/clients don't easiest to remember / URL as a brand misspellings by user input (in mobile phone or desktop browser) browsers not understanding protocol-less links total length of chars for easy user input method of peferance by major search engines/social media sites consistency sothat links dont fragment but all point to the same

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  • Why does switching users completely hang my system every time?

    - by Stéphane
    I have a fresh install of 11.04 64bit, with 2 administrator accounts and 4 normal accounts. The 4 normal accounts (the kids' accounts) don't have passwords, they can login simply by clicking on their names. When any of the users -- either admin or normal -- tries to switch to another account by clicking in the top-right corner of the screen and selecting another user, the screen goes black and the entire system locks up. Even CTRL+ALT+F1 through F7 does nothing. This is reproducible 100% of the time on this system. I can ssh into the box when the console locks up, and by running top, I see that Xorg is consuming about 100% of the CPU. Looking at the output of "ps axfu" in bash while the system is in this "locked up" state, here is the lightdm and X process tree: USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1153 0.0 0.1 183508 4292 ? Ssl Dec26 0:00 lightdm root 2187 0.4 4.6 265976 164168 tty7 Ss+ 00:43 0:21 \_ /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch stephane 2612 0.0 0.3 266400 10736 ? Ssl 01:52 0:00 \_ /usr/bin/gnome-session --session=ubuntu stephane 2650 0.0 0.0 12264 276 ? Ss 01:52 0:00 | \_ /usr/bin/ssh-agent /usr/bin/dbus-launch --exit-with-session /usr/bin/gnome-session --session=ubuntu stephane 2703 0.8 3.0 562068 106548 ? Sl 01:52 0:08 | \_ compiz stephane 2801 0.0 0.0 4264 584 ? Ss 01:52 0:00 | | \_ /bin/sh -c /usr/bin/compiz-decorator stephane 2802 0.0 0.3 265744 13772 ? Sl 01:52 0:00 | | \_ /usr/bin/unity-window-decorator ...cut... root 3024 80.6 0.3 107928 13088 tty8 Rs+ 01:53 12:34 \_ /usr/bin/X :1 -auth /var/run/lightdm/root/:1 -nolisten tcp vt8 -novtswitch That last process, pid #3024 in this case, is what has the CPU pegged. In case it matters (I suspect it might) here is what I think may be the relevant information for my video card, taken from /var/log/Xorg.0.log: [ 3392.653] (II) Loading /usr/lib/x86_64-linux-gnu/xorg/extra-modules/extra-modules.dpkg-tmp/modules/extensions/libglx.so [ 3392.653] (II) Module glx: vendor="FireGL - AMD Technologies Inc." [ 3392.653] compiled for 6.9.0, module version = 1.0.0 ... [ 3392.655] (II) LoadModule: "fglrx" [ 3392.655] (II) Loading /usr/lib/x86_64-linux-gnu/xorg/extra-modules/extra-modules.dpkg-tmp/modules/drivers/fglrx_drv.so [ 3392.672] (II) Module fglrx: vendor="FireGL - ATI Technologies Inc." [ 3392.672] compiled for 1.4.99.906, module version = 8.88.7 [ 3392.672] Module class: X.Org Video Driver ... [ 3392.759] (==) fglrx(0): ATI 2D Acceleration Architecture enabled [ 3392.759] (--) fglrx(0): Chipset: "AMD Radeon HD 6410D" (Chipset = 0x9644) Lastly: I did see this posting: Change user on 11.10 hangs system ...but I checked, and the libpam-smbpass package isn't installed on this system.

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  • Ubuntu (and any other linux os) not booting from cd or usb

    - by Amith
    I will tell you the whole story,one night when i was using KDE on Ubuntu 10.10 Kwin crashed then i shut down the os next day when i booted it the display came completely garbled and i went to safe graphics mode ,it worked and in reinstalled the Nvidia drivers and then restarted .Then immediatly, It said No init found Busybox XX.XX then I thought ill do a fresh install I inserted the ubuntu cd provided to me by Canonical.When i pressed 'try ubuntu without installing' instead of the graphic boot screen i saw.Ubuntu 10.10 in regular text and a progress bar few seconds after that the screen was flooded with error messages first alot of white then red.I then went to my win7 installation and saw a website which told me to find a Ext3 reader and format the ubuntu partition and the swap.I did that and when i restarted. GRUB configuration not found grub> Then it took my win 7 ERD and restored 7's bootloder Xp and 7 were working i put in the livecd again,Same error,Now usin my seven,Please help geeks,Ive even tried Knoppix,Fedora,Debiane.t.c they wont boot and i want to retain my win 7 and winxp partitions,I really miss linux.

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  • Accessing your web server via IPv6

    Being able to run your systems on IPv6, have automatic address assignment and the ability to resolve host names are the necessary building blocks in your IPv6 network infrastructure. Now, that everything is in place it is about time that we are going to enable another service to respond to IPv6 requests. The following article will guide through the steps on how to enable Apache2 httpd to listen and respond to incoming IPv6 requests. This is the fourth article in a series on IPv6 configuration: Configure IPv6 on your Linux system DHCPv6: Provide IPv6 information in your local network Enabling DNS for IPv6 infrastructure Accessing your web server via IPv6 Piece of advice: This is based on my findings on the internet while reading other people's helpful articles and going through a couple of man-pages on my local system. Surfing the web - IPv6 style Enabling IPv6 connections in Apache 2 is fairly simply. But first let's check whether your system has a running instance of Apache2 or not. You can check this like so: $ service apache2 status Apache2 is running (pid 2680). In case that you got a 'service unknown' you have to install Apache to proceed with the following steps: $ sudo apt-get install apache2 Out of the box, Apache binds to all your available network interfaces and listens to TCP port 80. To check this, run the following command: $ sudo netstat -lnptu | grep "apache2\W*$"tcp6       0      0 :::80                   :::*                    LISTEN      28306/apache2 In this case Apache2 is already binding to IPv6 (and implicitly to IPv4). If you only got a tcp output, then your HTTPd is not yet IPv6 enabled. Check your Listen directive, depending on your system this might be in a different location than the default in Ubuntu. $ sudo nano /etc/apache2/ports.conf # If you just change the port or add more ports here, you will likely also# have to change the VirtualHost statement in# /etc/apache2/sites-enabled/000-default# This is also true if you have upgraded from before 2.2.9-3 (i.e. from# Debian etch). See /usr/share/doc/apache2.2-common/NEWS.Debian.gz and# README.Debian.gzNameVirtualHost *:80Listen 80<IfModule mod_ssl.c>    # If you add NameVirtualHost *:443 here, you will also have to change    # the VirtualHost statement in /etc/apache2/sites-available/default-ssl    # to <VirtualHost *:443>    # Server Name Indication for SSL named virtual hosts is currently not    # supported by MSIE on Windows XP.    Listen 443</IfModule><IfModule mod_gnutls.c>    Listen 443</IfModule> Just in case that you don't have a ports.conf file, look for it like so: $ cd /etc/apache2/$ fgrep -r -i 'listen' ./* And modify the related file instead of the ports.conf. Which most probably might be either apache2.conf or httpd.conf anyways. Okay, please bear in mind that Apache can only bind once on the same interface and port. So, eventually, you might be interested to add another port which explicitly listens to IPv6 only. In that case, you would add the following in your configuration file: Listen 80Listen [2001:db8:bad:a55::2]:8080 But this is completely optional... Anyways, just to complete all steps, you save the file, and then check the syntax like so: $ sudo apache2ctl configtestSyntax OK Ok, now let's apply the modifications to our running Apache2 instances: $ sudo service apache2 reload * Reloading web server config apache2   ...done. $ sudo netstat -lnptu | grep "apache2\W*$"                                                                                               tcp6       0      0 2001:db8:bad:a55:::8080 :::*                    LISTEN      5922/apache2    tcp6       0      0 :::80                   :::*                    LISTEN      5922/apache2 There we have two daemons running and listening to different TCP ports. Now, that the basics are in place, it's time to prepare any website to respond to incoming requests on the IPv6 address. Open up any configuration file you have below your sites-enabled folder. $ ls -al /etc/apache2/sites-enabled/... $ sudo nano /etc/apache2/sites-enabled/000-default <VirtualHost *:80 [2001:db8:bad:a55::2]:8080>        ServerAdmin [email protected]        ServerName server.ios.mu        ServerAlias server Here, we have to check and modify the VirtualHost directive and enable it to respond to the IPv6 address and port our web server is listening to. Save your changes, run the configuration test and reload Apache2 in order to apply your modifications. After successful steps you can launch your favourite browser and navigate to your IPv6 enabled web server. Accessing an IPv6 address in the browser That looks like a successful surgery to me... Note: In case that you received a timeout, check whether your client is operating on IPv6, too.

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