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• Dual Boot issues with Windows 7 and Ubuntu

  - by Michael

  I'm finding myself in a rather unique situation. I've read through just about every resource I can find about this and while things have helped me understand some background, I haven't yet been able to find a solution. So I'm asking here. I originally had just a Windows 7 64-bit OS installation on my desktop. Learning that I couldn't do anything with Apache, PHP and MySql from within a 64-bit system, I did some research and found out that I could use Ubuntu. I've installed the latest version: 11.04. I created a CD to install Ubuntu from and the install went just fine. I installed it side-by-side with Windows 7. I can boot into Ubuntu just fine through the dual-boot option. When I reboot to load Windows though, the Grub2 list shows Windows 7 (loader) and when I select this option the Windows System Recovery loads instead of the actual OS. I haven't made it past there because I didn't know what to do. I just shut the computer down and rebooted into Ubuntu. I've been working for the last hour and a half to try to figure out how to boot into the Windows 7 OS and I haven't got a clue. While I'm somewhat proficient with Windows 7, I'm totally new to Ubuntu, so if you do know what needs to happen, please keep it simple enough that I'll be able to understand. Thanks for all your help in advance. Here's the results after using the Boot Info Script: Boot Info Script 0.55 dated February 15th, 2010 ============================= Boot Info Summary: ============================== => Grub 2 is installed in the MBR of /dev/sda and looks on the same drive in partition #5 for cbh. => Windows is installed in the MBR of /dev/sdb => Grub 2 is installed in the MBR of /dev/mapper/pdc_bdadcfbdif and looks on the same drive in partition #5 for cbh. sda1: _________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7 Boot sector info: No errors found in the Boot Parameter Block. Mounting failed: fuse: mount failed: Device or resource busy fuse: mount failed: Device or resource busy sda2: _________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7 Boot sector info: No errors found in the Boot Parameter Block. Mounting failed: fuse: mount failed: Device or resource busy fuse: mount failed: Device or resource busy fuse: mount failed: Device or resource busy fuse: mount failed: Device or resource busy sda3: _________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7 Boot sector info: No errors found in the Boot Parameter Block. Mounting failed: fuse: mount failed: Device or resource busy fuse: mount failed: Device or resource busy fuse: mount failed: Device or resource busy fuse: mount failed: Device or resource busy fuse: mount failed: Device or resource busy fuse: mount failed: Device or resource busy sdb1: _________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7 Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files/dirs: /bootmgr /Boot/BCD sdb2: _________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7 Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files/dirs: sdb3: _________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7 Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files/dirs: /bootmgr /boot/BCD sdb4: _________________________________________________________________________ File system: Extended Partition Boot sector type: - Boot sector info: sdb5: _________________________________________________________________________ File system: ext4 Boot sector type: - Boot sector info: Operating System: Ubuntu 11.04 Boot files/dirs: /boot/grub/grub.cfg /etc/fstab /boot/grub/core.img sdb6: _________________________________________________________________________ File system: swap Boot sector type: - Boot sector info: pdc_bdadcfbdif1: _________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7 Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files/dirs: /bootmgr /Boot/BCD pdc_bdadcfbdif2: _________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7 Boot sector info: No errors found in the Boot Parameter Block. Operating System: Windows 7 Boot files/dirs: /bootmgr /Boot/BCD /Windows/System32/winload.exe pdc_bdadcfbdif3: _________________________________________________________________________ File system: Boot sector type: Unknown Boot sector info: Mounting failed: fuse: mount failed: Device or resource busy fuse: mount failed: Device or resource busy fuse: mount failed: Device or resource busy fuse: mount failed: Device or resource busy fuse: mount failed: Device or resource busy fuse: mount failed: Device or resource busy mount: unknown filesystem type '' =========================== Drive/Partition Info: ============================= Drive: sda ___________________ _____________________________________________________ Disk /dev/sda: 750.2 GB, 750156374016 bytes 255 heads, 63 sectors/track, 91201 cylinders, total 1465149168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes Partition Boot Start End Size Id System /dev/sda1 * 2,048 206,847 204,800 7 HPFS/NTFS /dev/sda2 206,911 1,440,372,735 1,440,165,825 7 HPFS/NTFS /dev/sda3 1,440,372,736 1,464,856,575 24,483,840 7 HPFS/NTFS Drive: sdb ___________________ _____________________________________________________ Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes Partition Boot Start End Size Id System /dev/sdb1 * 2,048 206,847 204,800 7 HPFS/NTFS /dev/sdb2 206,911 1,342,554,688 1,342,347,778 7 HPFS/NTFS /dev/sdb3 1,930,344,448 1,953,521,663 23,177,216 7 HPFS/NTFS /dev/sdb4 1,342,556,158 1,930,344,447 587,788,290 5 Extended /dev/sdb5 1,342,556,160 1,896,806,399 554,250,240 83 Linux /dev/sdb6 1,896,808,448 1,930,344,447 33,536,000 82 Linux swap / Solaris Drive: pdc_bdadcfbdif ___________________ _____________________________________________________ Disk /dev/mapper/pdc_bdadcfbdif: 750.0 GB, 749999947776 bytes 255 heads, 63 sectors/track, 91182 cylinders, total 1464843648 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes Partition Boot Start End Size Id System /dev/mapper/pdc_bdadcfbdif1 * 2,048 206,847 204,800 7 HPFS/NTFS /dev/mapper/pdc_bdadcfbdif2 206,911 1,440,372,735 1,440,165,825 7 HPFS/NTFS /dev/mapper/pdc_bdadcfbdif3 1,440,372,736 1,464,856,575 24,483,840 7 HPFS/NTFS /dev/mapper/pdc_bdadcfbdif3 ends after the last sector of /dev/mapper/pdc_bdadcfbdif blkid -c /dev/null: ____________________________________________________________ Device UUID TYPE LABEL /dev/mapper/pdc_bdadcfbdif1 888E54CC8E54B482 ntfs SYSTEM /dev/mapper/pdc_bdadcfbdif2 C2766BF6766BEA1D ntfs OS /dev/mapper/pdc_bdadcfbdif: PTTYPE="dos" /dev/sda1 888E54CC8E54B482 ntfs SYSTEM /dev/sda2 C2766BF6766BEA1D ntfs OS /dev/sda3 BE6CA31D6CA2CF87 ntfs HP_RECOVERY /dev/sda promise_fasttrack_raid_member /dev/sdb1 20B65685B6565B7C ntfs SYSTEM /dev/sdb2 B4467A314679F508 ntfs HP /dev/sdb3 6E10B7A410B77227 ntfs FACTORY_IMAGE /dev/sdb4: PTTYPE="dos" /dev/sdb5 266f9801-cf4f-4acc-affa-2092be035f0c ext4 /dev/sdb6 1df35749-a887-45ff-a3de-edd52239847d swap /dev/sdb: PTTYPE="dos" error: /dev/mapper/pdc_bdadcfbdif3: No such file or directory error: /dev/sdc: No medium found error: /dev/sdd: No medium found error: /dev/sde: No medium found error: /dev/sdf: No medium found error: /dev/sdg: No medium found ============================ "mount | grep ^/dev output: =========================== Device Mount_Point Type Options /dev/sdb5 / ext4 (rw,errors=remount-ro,commit=0) =========================== sdb5/boot/grub/grub.cfg: =========================== # # DO NOT EDIT THIS FILE # # It is automatically generated by grub-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub # ### BEGIN /etc/grub.d/00_header ### if [ -s $prefix/grubenv ]; then set have_grubenv=true load_env fi set default="0" if [ "${prev_saved_entry}" ]; then set saved_entry="${prev_saved_entry}" save_env saved_entry set prev_saved_entry= save_env prev_saved_entry set boot_once=true fi function savedefault { if [ -z "${boot_once}" ]; then saved_entry="${chosen}" save_env saved_entry fi } function recordfail { set recordfail=1 if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi } function load_video { insmod vbe insmod vga insmod video_bochs insmod video_cirrus } insmod part_msdos insmod ext2 set root='(/dev/sdb,msdos5)' search --no-floppy --fs-uuid --set=root 266f9801-cf4f-4acc-affa-2092be035f0c if loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=auto load_video insmod gfxterm fi terminal_output gfxterm insmod part_msdos insmod ext2 set root='(/dev/sdb,msdos5)' search --no-floppy --fs-uuid --set=root 266f9801-cf4f-4acc-affa-2092be035f0c set locale_dir=($root)/boot/grub/locale set lang=en_US insmod gettext if [ "${recordfail}" = 1 ]; then set timeout=-1 else set timeout=10 fi ### END /etc/grub.d/00_header ### ### BEGIN /etc/grub.d/05_debian_theme ### set menu_color_normal=white/black set menu_color_highlight=black/light-gray if background_color 44,0,30; then clear fi ### END /etc/grub.d/05_debian_theme ### ### BEGIN /etc/grub.d/10_linux ### if [ ${recordfail} != 1 ]; then if [ -e ${prefix}/gfxblacklist.txt ]; then if hwmatch ${prefix}/gfxblacklist.txt 3; then if [ ${match} = 0 ]; then set linux_gfx_mode=keep else set linux_gfx_mode=text fi else set linux_gfx_mode=text fi else set linux_gfx_mode=keep fi else set linux_gfx_mode=text fi export linux_gfx_mode if [ "$linux_gfx_mode" != "text" ]; then load_video; fi menuentry 'Ubuntu, with Linux 2.6.38-8-generic-pae' --class ubuntu --class gnu-linux --class gnu --class os { recordfail set gfxpayload=$linux_gfx_mode insmod part_msdos insmod ext2 set root='(/dev/sdb,msdos5)' search --no-floppy --fs-uuid --set=root 266f9801-cf4f-4acc-affa-2092be035f0c linux /boot/vmlinuz-2.6.38-8-generic-pae root=UUID=266f9801-cf4f-4acc- affa-2092be035f0c ro quiet splash vt.handoff=7 initrd /boot/initrd.img-2.6.38-8-generic-pae } menuentry 'Ubuntu, with Linux 2.6.38-8-generic-pae (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail set gfxpayload=$linux_gfx_mode insmod part_msdos insmod ext2 set root='(/dev/sdb,msdos5)' search --no-floppy --fs-uuid --set=root 266f9801-cf4f-4acc-affa-2092be035f0c echo 'Loading Linux 2.6.38-8-generic-pae ...' linux /boot/vmlinuz-2.6.38-8-generic-pae root=UUID=266f9801-cf4f-4acc-affa-2092be035f0c ro single echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-2.6.38-8-generic-pae } ### END /etc/grub.d/10_linux ### ### BEGIN /etc/grub.d/20_linux_xen ### ### END /etc/grub.d/20_linux_xen ### ### BEGIN /etc/grub.d/20_memtest86+ ### menuentry "Memory test (memtest86+)" { insmod part_msdos insmod ext2 set root='(/dev/sdb,msdos5)' search --no-floppy --fs-uuid --set=root 266f9801-cf4f-4acc-affa-2092be035f0c linux16 /boot/memtest86+.bin } menuentry "Memory test (memtest86+, serial console 115200)" { insmod part_msdos insmod ext2 set root='(/dev/sdb,msdos5)' search --no-floppy --fs-uuid --set=root 266f9801-cf4f-4acc-affa-2092be035f0c linux16 /boot/memtest86+.bin console=ttyS0,115200n8 } ### END /etc/grub.d/20_memtest86+ ### ### BEGIN /etc/grub.d/30_os-prober ### menuentry "Windows 7 (loader) (on /dev/sdb1)" --class windows --class os { insmod part_msdos insmod ntfs set root='(/dev/sdb,msdos1)' search --no-floppy --fs-uuid --set=root 20B65685B6565B7C chainloader +1 } menuentry "Windows Recovery Environment (loader) (on /dev/sdb3)" --class windows --class os { insmod part_msdos insmod ntfs set root='(/dev/sdb,msdos3)' search --no-floppy --fs-uuid --set=root 6E10B7A410B77227 drivemap -s (hd0) ${root} chainloader +1 } ### END /etc/grub.d/30_os-prober ### ### BEGIN /etc/grub.d/40_custom ### # This file provides an easy way to add custom menu entries. Simply type the # menu entries you want to add after this comment. Be careful not to change # the 'exec tail' line above. ### END /etc/grub.d/40_custom ### ### BEGIN /etc/grub.d/41_custom ### if [ -f $prefix/custom.cfg ]; then source $prefix/custom.cfg; fi ### END /etc/grub.d/41_custom ### =============================== sdb5/etc/fstab: =============================== # /etc/fstab: static file system information. # # Use 'blkid -o value -s UUID' to print the universally unique identifier # for a device; this may be used with UUID= as a more robust way to name # devices that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc nodev,noexec,nosuid 0 0 # / was on /dev/sdb5 during installation UUID=266f9801-cf4f-4acc-affa-2092be035f0c / ext4 errors=remount-ro 0 1 # swap was on /dev/sdb6 during installation UUID=1df35749-a887-45ff-a3de-edd52239847d none swap sw 0 0 =================== sdb5: Location of files loaded by Grub: =================== 900.1GB: boot/grub/core.img 825.0GB: boot/grub/grub.cfg 688.7GB: boot/initrd.img-2.6.38-8-generic-pae 688.0GB: boot/vmlinuz-2.6.38-8-generic-pae 688.7GB: initrd.img 688.0GB: vmlinuz =========================== Unknown MBRs/Boot Sectors/etc ======================= Unknown BootLoader on pdc_bdadcfbdif3 =======Devices which don't seem to have a corresponding hard drive============== sdc sdd sde sdf sdg =============================== StdErr Messages: =============================== ERROR: dos: partition address past end of RAID device hexdump: /dev/mapper/pdc_bdadcfbdif3: No such file or directory hexdump: /dev/mapper/pdc_bdadcfbdif3: No such file or directory ERROR: dos: partition address past end of RAID device

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• Red Gate Coder interviews: Alex Davies

  - by Michael Williamson

  Alex Davies has been a software engineer at Red Gate since graduating from university, and is currently busy working on .NET Demon. We talked about tackling parallel programming with his actors framework, a scientific approach to debugging, and how JavaScript is going to affect the programming languages we use in years to come. So, if we start at the start, how did you get started in programming? When I was seven or eight, I was given a BBC Micro for Christmas. I had asked for a Game Boy, but my dad thought it would be better to give me a proper computer. For a year or so, I only played games on it, but then I found the user guide for writing programs in it. I gradually started doing more stuff on it and found it fun. I liked creating. As I went into senior school I continued to write stuff on there, trying to write games that weren’t very good. I got a real computer when I was fourteen and found ways to write BASIC on it. Visual Basic to start with, and then something more interesting than that. How did you learn to program? Was there someone helping you out? Absolutely not! I learnt out of a book, or by experimenting. I remember the first time I found a loop, I was like “Oh my God! I don’t have to write out the same line over and over and over again any more. It’s amazing!” When did you think this might be something that you actually wanted to do as a career? For a long time, I thought it wasn’t something that you would do as a career, because it was too much fun to be a career. I thought I’d do chemistry at university and some kind of career based on chemical engineering. And then I went to a careers fair at school when I was seventeen or eighteen, and it just didn’t interest me whatsoever. I thought “I could be a programmer, and there’s loads of money there, and I’m good at it, and it’s fun”, but also that I shouldn’t spoil my hobby. Now I don’t really program in my spare time any more, which is a bit of a shame, but I program all the rest of the time, so I can live with it. Do you think you learnt much about programming at university? Yes, definitely! I went into university knowing how to make computers do anything I wanted them to do. However, I didn’t have the language to talk about algorithms, so the algorithms course in my first year was massively important. Learning other language paradigms like functional programming was really good for breadth of understanding. Functional programming influences normal programming through design rather than actually using it all the time. I draw inspiration from it to write imperative programs which I think is actually becoming really fashionable now, but I’ve been doing it for ages. I did it first! There were also some courses on really odd programming languages, a bit of Prolog, a little bit of C. Having a little bit of each of those is something that I would have never done on my own, so it was important. And then there are knowledge-based courses which are about not programming itself but things that have been programmed like TCP. Those are really important for examples for how to approach things. Did you do any internships while you were at university? Yeah, I spent both of my summers at the same company. I thought I could code well before I went there. Looking back at the crap that I produced, it was only surpassed in its crappiness by all of the other code already in that company. I’m so much better at writing nice code now than I used to be back then. Was there just not a culture of looking after your code? There was, they just didn’t hire people for their abilities in that area. They hired people for raw IQ. The first indicator of it going wrong was that they didn’t have any computer scientists, which is a bit odd in a programming company. But even beyond that they didn’t have people who learnt architecture from anyone else. Most of them had started straight out of university, so never really had experience or mentors to learn from. There wasn’t the experience to draw from to teach each other. In the second half of my second internship, I was being given tasks like looking at new technologies and teaching people stuff. Interns shouldn’t be teaching people how to do their jobs! All interns are going to have little nuggets of things that you don’t know about, but they shouldn’t consistently be the ones who know the most. It’s not a good environment to learn. I was going to ask how you found working with people who were more experienced than you… When I reached Red Gate, I found some people who were more experienced programmers than me, and that was difficult. I’ve been coding since I was tiny. At university there were people who were cleverer than me, but there weren’t very many who were more experienced programmers than me. During my internship, I didn’t find anyone who I classed as being a noticeably more experienced programmer than me. So, it was a shock to the system to have valid criticisms rather than just formatting criticisms. However, Red Gate’s not so big on the actual code review, at least it wasn’t when I started. We did an entire product release and then somebody looked over all of the UI of that product which I’d written and say what they didn’t like. By that point, it was way too late and I’d disagree with them. Do you think the lack of code reviews was a bad thing? I think if there’s going to be any oversight of new people, then it should be continuous rather than chunky. For me I don’t mind too much, I could go out and get oversight if I wanted it, and in those situations I felt comfortable without it. If I was managing the new person, then maybe I’d be keener on oversight and then the right way to do it is continuously and in very, very small chunks. Have you had any significant projects you’ve worked on outside of a job? When I was a teenager I wrote all sorts of stuff. I used to write games, I derived how to do isomorphic projections myself once. I didn’t know what the word was so I couldn’t Google for it, so I worked it out myself. It was horrifically complicated. But it sort of tailed off when I started at university, and is now basically zero. If I do side-projects now, they tend to be work-related side projects like my actors framework, NAct, which I started in a down tools week. Could you explain a little more about NAct? It is a little C# framework for writing parallel code more easily. Parallel programming is difficult when you need to write to shared data. Sometimes parallel programming is easy because you don’t need to write to shared data. When you do need to access shared data, you could just have your threads pile in and do their work, but then you would screw up the data because the threads would trample on each other’s toes. You could lock, but locks are really dangerous if you’re using more than one of them. You get interactions like deadlocks, and that’s just nasty. Actors instead allows you to say this piece of data belongs to this thread of execution, and nobody else can read it. If you want to read it, then ask that thread of execution for a piece of it by sending a message, and it will send the data back by a message. And that avoids deadlocks as long as you follow some obvious rules about not making your actors sit around waiting for other actors to do something. There are lots of ways to write actors, NAct allows you to do it as if it was method calls on other objects, which means you get all the strong type-safety that C# programmers like. Do you think that this is suitable for the majority of parallel programming, or do you think it’s only suitable for specific cases? It’s suitable for most difficult parallel programming. If you’ve just got a hundred web requests which are all independent of each other, then I wouldn’t bother because it’s easier to just spin them up in separate threads and they can proceed independently of each other. But where you’ve got difficult parallel programming, where you’ve got multiple threads accessing multiple bits of data in multiple ways at different times, then actors is at least as good as all other ways, and is, I reckon, easier to think about. When you’re using actors, you presumably still have to write your code in a different way from you would otherwise using single-threaded code. You can’t use actors with any methods that have return types, because you’re not allowed to call into another actor and wait for it. If you want to get a piece of data out of another actor, then you’ve got to use tasks so that you can use “async” and “await” to await asynchronously for it. But other than that, you can still stick things in classes so it’s not too different really. Rather than having thousands of objects with mutable state, you can use component-orientated design, where there are only a few mutable classes which each have a small number of instances. Then there can be thousands of immutable objects. If you tend to do that anyway, then actors isn’t much of a jump. If I’ve already built my system without any parallelism, how hard is it to add actors to exploit all eight cores on my desktop? Usually pretty easy. If you can identify even one boundary where things look like messages and you have components where some objects live on one side and these other objects live on the other side, then you can have a granddaddy object on one side be an actor and it will parallelise as it goes across that boundary. Not too difficult. If we do get 1000-core desktop PCs, do you think actors will scale up? It’s hard. There are always in the order of twenty to fifty actors in my whole program because I tend to write each component as actors, and I tend to have one instance of each component. So this won’t scale to a thousand cores. What you can do is write data structures out of actors. I use dictionaries all over the place, and if you need a dictionary that is going to be accessed concurrently, then you could build one of those out of actors in no time. You can use queuing to marshal requests between different slices of the dictionary which are living on different threads. So it’s like a distributed hash table but all of the chunks of it are on the same machine. That means that each of these thousand processors has cached one small piece of the dictionary. I reckon it wouldn’t be too big a leap to start doing proper parallelism. Do you think it helps if actors get baked into the language, similarly to Erlang? Erlang is excellent in that it has thread-local garbage collection. C# doesn’t, so there’s a limit to how well C# actors can possibly scale because there’s a single garbage collected heap shared between all of them. When you do a global garbage collection, you’ve got to stop all of the actors, which is seriously expensive, whereas in Erlang garbage collections happen per-actor, so they’re insanely cheap. However, Erlang deviated from all the sensible language design that people have used recently and has just come up with crazy stuff. You can definitely retrofit thread-local garbage collection to .NET, and then it’s quite well-suited to support actors, even if it’s not baked into the language. Speaking of language design, do you have a favourite programming language? I’ll choose a language which I’ve never written before. I like the idea of Scala. It sounds like C#, only with some of the niggles gone. I enjoy writing static types. It means you don’t have to writing tests so much. When you say it doesn’t have some of the niggles? C# doesn’t allow the use of a property as a method group. It doesn’t have Scala case classes, or sum types, where you can do a switch statement and the compiler checks that you’ve checked all the cases, which is really useful in functional-style programming. Pattern-matching, in other words. That’s actually the major niggle. C# is pretty good, and I’m quite happy with C#. And what about going even further with the type system to remove the need for tests to something like Haskell? Or is that a step too far? I’m quite a pragmatist, I don’t think I could deal with trying to write big systems in languages with too few other users, especially when learning how to structure things. I just don’t know anyone who can teach me, and the Internet won’t teach me. That’s the main reason I wouldn’t use it. If I turned up at a company that writes big systems in Haskell, I would have no objection to that, but I wouldn’t instigate it. What about things in C#? For instance, there’s contracts in C#, so you can try to statically verify a bit more about your code. Do you think that’s useful, or just not worthwhile? I’ve not really tried it. My hunch is that it needs to be built into the language and be quite mathematical for it to work in real life, and that doesn’t seem to have ended up true for C# contracts. I don’t think anyone who’s tried them thinks they’re any good. I might be wrong. On a slightly different note, how do you like to debug code? I think I’m quite an odd debugger. I use guesswork extremely rarely, especially if something seems quite difficult to debug. I’ve been bitten spending hours and hours on guesswork and not being scientific about debugging in the past, so now I’m scientific to a fault. What I want is to see the bug happening in the debugger, to step through the bug happening. To watch the program going from a valid state to an invalid state. When there’s a bug and I can’t work out why it’s happening, I try to find some piece of evidence which places the bug in one section of the code. From that experiment, I binary chop on the possible causes of the bug. I suppose that means binary chopping on places in the code, or binary chopping on a stage through a processing cycle. Basically, I’m very stupid about how I debug. I won’t make any guesses, I won’t use any intuition, I will only identify the experiment that’s going to binary chop most effectively and repeat rather than trying to guess anything. I suppose it’s quite top-down. Is most of the time then spent in the debugger? Absolutely, if at all possible I will never debug using print statements or logs. I don’t really hold much stock in outputting logs. If there’s any bug which can be reproduced locally, I’d rather do it in the debugger than outputting logs. And with SmartAssembly error reporting, there’s not a lot that can’t be either observed in an error report and just fixed, or reproduced locally. And in those other situations, maybe I’ll use logs. But I hate using logs. You stare at the log, trying to guess what’s going on, and that’s exactly what I don’t like doing. You have to just look at it and see does this look right or wrong. We’ve covered how you get to grip with bugs. How do you get to grips with an entire codebase? I watch it in the debugger. I find little bugs and then try to fix them, and mostly do it by watching them in the debugger and gradually getting an understanding of how the code works using my process of binary chopping. I have to do a lot of reading and watching code to choose where my slicing-in-half experiment is going to be. The last time I did it was SmartAssembly. The old code was a complete mess, but at least it did things top to bottom. There wasn’t too much of some of the big abstractions where flow of control goes all over the place, into a base class and back again. Code’s really hard to understand when that happens. So I like to choose a little bug and try to fix it, and choose a bigger bug and try to fix it. Definitely learn by doing. I want to always have an aim so that I get a little achievement after every few hours of debugging. Once I’ve learnt the codebase I might be able to fix all the bugs in an hour, but I’d rather be using them as an aim while I’m learning the codebase. If I was a maintainer of a codebase, what should I do to make it as easy as possible for you to understand? Keep distinct concepts in different places. And name your stuff so that it’s obvious which concepts live there. You shouldn’t have some variable that gets set miles up the top of somewhere, and then is read miles down to choose some later behaviour. I’m talking from a very much SmartAssembly point of view because the old SmartAssembly codebase had tons and tons of these things, where it would read some property of the code and then deal with it later. Just thousands of variables in scope. Loads of things to think about. If you can keep concepts separate, then it aids me in my process of fixing bugs one at a time, because each bug is going to more or less be understandable in the one place where it is. And what about tests? Do you think they help at all? I’ve never had the opportunity to learn a codebase which has had tests, I don’t know what it’s like! What about when you’re actually developing? How useful do you find tests in finding bugs or regressions? Finding regressions, absolutely. Running bits of code that would be quite hard to run otherwise, definitely. It doesn’t happen very often that a test finds a bug in the first place. I don’t really buy nebulous promises like tests being a good way to think about the spec of the code. My thinking goes something like “This code works at the moment, great, ship it! Ah, there’s a way that this code doesn’t work. Okay, write a test, demonstrate that it doesn’t work, fix it, use the test to demonstrate that it’s now fixed, and keep the test for future regressions.” The most valuable tests are for bugs that have actually happened at some point, because bugs that have actually happened at some point, despite the fact that you think you’ve fixed them, are way more likely to appear again than new bugs are. Does that mean that when you write your code the first time, there are no tests? Often. The chance of there being a bug in a new feature is relatively unaffected by whether I’ve written a test for that new feature because I’m not good enough at writing tests to think of bugs that I would have written into the code. So not writing regression tests for all of your code hasn’t affected you too badly? There are different kinds of features. Some of them just always work, and are just not flaky, they just continue working whatever you throw at them. Maybe because the type-checker is particularly effective around them. Writing tests for those features which just tend to always work is a waste of time. And because it’s a waste of time I’ll tend to wait until a feature has demonstrated its flakiness by having bugs in it before I start trying to test it. You can get a feel for whether it’s going to be flaky code as you’re writing it. I try to write it to make it not flaky, but there are some things that are just inherently flaky. And very occasionally, I’ll think “this is going to be flaky” as I’m writing, and then maybe do a test, but not most of the time. How do you think your programming style has changed over time? I’ve got clearer about what the right way of doing things is. I used to flip-flop a lot between different ideas. Five years ago I came up with some really good ideas and some really terrible ideas. All of them seemed great when I thought of them, but they were quite diverse ideas, whereas now I have a smaller set of reliable ideas that are actually good for structuring code. So my code is probably more similar to itself than it used to be back in the day, when I was trying stuff out. I’ve got more disciplined about encapsulation, I think. There are operational things like I use actors more now than I used to, and that forces me to use immutability more than I used to. The first code that I wrote in Red Gate was the memory profiler UI, and that was an actor, I just didn’t know the name of it at the time. I don’t really use object-orientation. By object-orientation, I mean having n objects of the same type which are mutable. I want a constant number of objects that are mutable, and they should be different types. I stick stuff in dictionaries and then have one thing that owns the dictionary and puts stuff in and out of it. That’s definitely a pattern that I’ve seen recently. I think maybe I’m doing functional programming. Possibly. It’s plausible. If you had to summarise the essence of programming in a pithy sentence, how would you do it? Programming is the form of art that, without losing any of the beauty of architecture or fine art, allows you to produce things that people love and you make money from. So you think it’s an art rather than a science? It’s a little bit of engineering, a smidgeon of maths, but it’s not science. Like architecture, programming is on that boundary between art and engineering. If you want to do it really nicely, it’s mostly art. You can get away with doing architecture and programming entirely by having a good engineering mind, but you’re not going to produce anything nice. You’re not going to have joy doing it if you’re an engineering mind. Architects who are just engineering minds are not going to enjoy their job. I suppose engineering is the foundation on which you build the art. Exactly. How do you think programming is going to change over the next ten years? There will be an unfortunate shift towards dynamically-typed languages, because of JavaScript. JavaScript has an unfair advantage. JavaScript’s unfair advantage will cause more people to be exposed to dynamically-typed languages, which means other dynamically-typed languages crop up and the best features go into dynamically-typed languages. Then people conflate the good features with the fact that it’s dynamically-typed, and more investment goes into dynamically-typed languages. They end up better, so people use them. What about the idea of compiling other languages, possibly statically-typed, to JavaScript? It’s a reasonable idea. I would like to do it, but I don’t think enough people in the world are going to do it to make it pick up. The hordes of beginners are the lifeblood of a language community. They are what makes there be good tools and what makes there be vibrant community websites. And any particular thing which is the same as JavaScript only with extra stuff added to it, although it might be technically great, is not going to have the hordes of beginners. JavaScript is always to be quickest and easiest way for a beginner to start programming in the browser. And dynamically-typed languages are great for beginners. Compilers are pretty scary and beginners don’t write big code. And having your errors come up in the same place, whether they’re statically checkable errors or not, is quite nice for a beginner. If someone asked me to teach them some programming, I’d teach them JavaScript. If dynamically-typed languages are great for beginners, when do you think the benefits of static typing start to kick in? The value of having a statically typed program is in the tools that rely on the static types to produce a smooth IDE experience rather than actually telling me my compile errors. And only once you’re experienced enough a programmer that having a really smooth IDE experience makes a blind bit of difference, does static typing make a blind bit of difference. So it’s not really about size of codebase. If I go and write up a tiny program, I’m still going to get value out of writing it in C# using ReSharper because I’m experienced with C# and ReSharper enough to be able to write code five times faster if I have that help. Any other visions of the future? Nobody’s going to use actors. Because everyone’s going to be running on single-core VMs connected over network-ready protocols like JSON over HTTP. So, parallelism within one operating system is going to die. But until then, you should use actors. More Red Gater Coder interviews

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• Replacing “if”s with your own number system

  - by Michael Williamson

  During our second code retreat at Red Gate, the restriction for one of the sessions was disallowing the use of if statements. That includes other constructs that have the same effect, such as switch statements or loops that will only be executed zero or one times. The idea is to encourage use of polymorphism instead, and see just how far it can be used to get rid of “if”s. The main place where people struggled to get rid of numbers from their implementation of Conway’s Game of Life was the piece of code that decides whether a cell is live or dead in the next generation. For instance, for a cell that’s currently live, the code might look something like this: if (numberOfNeighbours == 2 || numberOfNeighbours == 3) { return CellState.LIVE; } else { return CellState.DEAD; } The problem is that we need to change behaviour depending on the number of neighbours each cell has, but polymorphism only allows us to switch behaviour based on the type of a value. It follows that the solution is to make different numbers have different types: public interface IConwayNumber { IConwayNumber Increment(); CellState LiveCellNextGeneration(); } public class Zero : IConwayNumber { public IConwayNumber Increment() { return new One(); } public CellState LiveCellNextGeneration() { return CellState.DEAD; } } public class One : IConwayNumber { public IConwayNumber Increment() { return new Two(); } public CellState LiveCellNextGeneration() { return CellState.LIVE; } } public class Two : IConwayNumber { public IConwayNumber Increment() { return new ThreeOrMore(); } public CellState LiveCellNextGeneration() { return CellState.LIVE; } } public class ThreeOrMore : IConwayNumber { public IConwayNumber Increment() { return this; } public CellState LiveCellNextGeneration() { return CellState.DEAD; } } In the code that counts the number of neighbours, we use our new number system by starting with Zero and incrementing when we find a neighbour. To choose the next state of the cell, rather than inspecting the number of neighbours, we ask the number of neighbours for the next state directly: return numberOfNeighbours.LiveCellNextGeneration(); And now we have no “if”s! If C# had double-dispatch, or if we used the visitor pattern, we could move the logic for choosing the next cell out of the number classes, which might feel a bit more natural. I suspect that reimplementing the natural numbers is still going to feel about the same amount of crazy though.

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• Access Insurance Company Wins 2010 Technology Innovation Award at IASA

  - by [email protected]

  Helen Pitts, senior product marketing manager for Oracle Insurance, is blogging from the 2010 IASA Annual Conference and Business Show this week. For the second time in two weeks an Oracle Insurance customer has earned recognition at an insurance industry event for its innovative use of technology to transform their business. Access Insurance Company received the 2010 Technology Innovation Award during the 2010 IASA Annual Conference and Business Show this week in Grapevine, Texas. The company earned the recognition for its "Instant Access" application, which executes all the business rules and processes needed to provide a quote, bind, and issue a policy. CIO Andy Dunn and Tim Reynolds stopped by the Oracle Insurance Booth at IASA to visit with the team, show their award, and share how the platform has provided a strategic advantage to the company and helped it increase revenue by penetrating new markets, increasing market share and improving customer retention. Since implementing Instant Access in 2009 - a platform that leverages both Oracle Insurance Insbridge Rating and Underwriting and Oracle Documaker - the carrier has: Increased policies in force by 22%, from 140,185 to more than 270,000 Grown market share by 4.6% Increased 2009 revenue by 26.5% Increased ratio of policyholders per CSR by 30% Increased its appointed independent producers by 43 percent Now that's true innovation! You can learn more about the company's formula for success by reading Access Insurance Holdings CEO and president Michael McMenamin's interview with Insurance & Technology, Data Mastery Drives Access Insurance's 'Instant Access' Business Technology Platform. Congratulations to Michael, Andy, Tim and the entire team at Access Insurance on this well deserved honor - and for your role as a technology leader for the industry. Helen Pitts is senior product marketing manager for Oracle Insurance.

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• AppFabric Caching Feedback

  - by Michael Stephenson

  We are running a survey to collect feedback around scenarios where people were experimenting with velocity on windows 2003 in the CTP but are now in a position where the beta requires windows 2008. We would like to understand how important this scenario is precieved to be. If you are in the Connected Systems Community and would like to provide feedback please complete the following survey http://www.surveymonkey.com/s/N3VKZWN

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• Revisiting ANTS Performance Profiler 7.4

  - by James Michael Hare

  Last year, I did a small review on the ANTS Performance Profiler 6.3, now that it’s a year later and a major version number higher, I thought I’d revisit the review and revise my last post. This post will take the same examples as the original post and update them to show what’s new in version 7.4 of the profiler. Background A performance profiler’s main job is to keep track of how much time is typically spent in each unit of code. This helps when we have a program that is not running at the performance we expect, and we want to know where the program is experiencing issues. There are many profilers out there of varying capabilities. Red Gate’s typically seem to be the very easy to “jump in” and get started with very little training required. So let’s dig into the Performance Profiler. I’ve constructed a very crude program with some obvious inefficiencies. It’s a simple program that generates random order numbers (or really could be any unique identifier), adds it to a list, sorts the list, then finds the max and min number in the list. Ignore the fact it’s very contrived and obviously inefficient, we just want to use it as an example to show off the tool: 1: // our test program 2: public static class Program 3: { 4: // the number of iterations to perform 5: private static int _iterations = 1000000; 6: 7: // The main method that controls it all 8: public static void Main() 9: { 10: var list = new List<string>(); 11: 12: for (int i = 0; i < _iterations; i++) 13: { 14: var x = GetNextId(); 15: 16: AddToList(list, x); 17: 18: var highLow = GetHighLow(list); 19: 20: if ((i % 1000) == 0) 21: { 22: Console.WriteLine("{0} - High: {1}, Low: {2}", i, highLow.Item1, highLow.Item2); 23: Console.Out.Flush(); 24: } 25: } 26: } 27: 28: // gets the next order id to process (random for us) 29: public static string GetNextId() 30: { 31: var random = new Random(); 32: var num = random.Next(1000000, 9999999); 33: return num.ToString(); 34: } 35: 36: // add it to our list - very inefficiently! 37: public static void AddToList(List<string> list, string item) 38: { 39: list.Add(item); 40: list.Sort(); 41: } 42: 43: // get high and low of order id range - very inefficiently! 44: public static Tuple<int,int> GetHighLow(List<string> list) 45: { 46: return Tuple.Create(list.Max(s => Convert.ToInt32(s)), list.Min(s => Convert.ToInt32(s))); 47: } 48: } So let’s run it through the profiler and see what happens! Visual Studio Integration First, let’s look at how the ANTS profilers integrate with Visual Studio’s menu system. Once you install the ANTS profilers, you will get an ANTS menu item with several options: Notice that you can either Profile Performance or Launch ANTS Performance Profiler. These sound similar but achieve two slightly different actions: Profile Performance: this immediately launches the profiler with all defaults selected to profile the active project in Visual Studio. Launch ANTS Performance Profiler: this launches the profiler much the same way as starting it from the Start Menu. The profiler will pre-populate the application and path information, but allow you to change the settings before beginning the profile run. So really, the main difference is that Profile Performance immediately begins profiling with the default selections, where Launch ANTS Performance Profiler allows you to change the defaults and attach to an already-running application. Let’s Fire it Up! So when you fire up ANTS either via Start Menu or Launch ANTS Performance Profiler menu in Visual Studio, you are presented with a very simple dialog to get you started: Notice you can choose from many different options for application type. You can profile executables, services, web applications, or just attach to a running process. In fact, in version 7.4 we see two new options added: ASP.NET Web Application (IIS Express) SharePoint web application (IIS) So this gives us an additional way to profile ASP.NET applications and the ability to profile SharePoint applications as well. You can also choose your level of detail in the Profiling Mode drop down. If you choose Line-Level and method-level timings detail, you will get a lot more detail on the method durations, but this will also slow down profiling somewhat. If you really need the profiler to be as unintrusive as possible, you can change it to Sample method-level timings. This is performing very light profiling, where basically the profiler collects timings of a method by examining the call-stack at given intervals. Which method you choose depends a lot on how much detail you need to find the issue and how sensitive your program issues are to timing. So for our example, let’s just go with the line and method timing detail. So, we check that all the options are correct (if you launch from VS2010, the executable and path are filled in already), and fire it up by clicking the [Start Profiling] button. Profiling the Application Once you start profiling the application, you will see a real-time graph of CPU usage that will indicate how much your application is using the CPU(s) on your system. During this time, you can select segments of the graph and bookmark them, giving them mnemonic names. This can be useful if you want to compare performance in one part of the run to another part of the run. Notice that once you select a block, it will give you the call tree breakdown for that selection only, and the relative performance of those calls. Once you feel you have collected enough information, you can click [Stop Profiling] to stop the application run and information collection and begin a more thorough analysis. Analyzing Method Timings So now that we’ve halted the run, we can look around the GUI and see what we can see. By default, the times are shown in terms of percentage of time of the total run of the application, though you can change it in the View menu item to milliseconds, ticks, or seconds as well. This won’t affect the percentages of methods, it only affects what units the times are shown. Notice also that the major hotspot seems to be in a method without source, ANTS Profiler will filter these out by default, but you can right-click on the line and remove the filter to see more detail. This proves especially handy when a bottleneck is due to a method in the BCL. So now that we’ve removed the filter, we see a bit more detail: In addition, ANTS Performance Profiler gives you the ability to decompile the methods without source so that you can dive even deeper, though typically this isn’t necessary for our purposes. When looking at timings, there are generally two types of timings for each method call: Time: This is the time spent ONLY in this method, not including calls this method makes to other methods. Time With Children: This is the total of time spent in both this method AND including calls this method makes to other methods. In other words, the Time tells you how much work is being done exclusively in this method, and the Time With Children tells you how much work is being done inclusively in this method and everything it calls. You can also choose to display the methods in a tree or in a grid. The tree view is the default and it shows the method calls arranged in terms of the tree representing all method calls and the parent method that called them, etc. This is useful for when you find a hot-spot method, you can see who is calling it to determine if the problem is the method itself, or if it is being called too many times. The grid method represents each method only once with its totals and is useful for quickly seeing what method is the trouble spot. In addition, you can choose to display Methods with source which are generally the methods you wrote (as opposed to native or BCL code), or Any Method which shows not only your methods, but also native calls, JIT overhead, synchronization waits, etc. So these are just two ways of viewing the same data, and you’re free to choose the organization that best suits what information you are after. Analyzing Method Source If we look at the timings above, we see that our AddToList() method (and in particular, it’s call to the List<T>.Sort() method in the BCL) is the hot-spot in this analysis. If ANTS sees a method that is consuming the most time, it will flag it as a hot-spot to help call out potential areas of concern. This doesn’t mean the other statistics aren’t meaningful, but that the hot-spot is most likely going to be your biggest bang-for-the-buck to concentrate on. So let’s select the AddToList() method, and see what it shows in the source window below: Notice the source breakout in the bottom pane when you select a method (from either tree or grid view). This shows you the timings in this method per line of code. This gives you a major indicator of where the trouble-spot in this method is. So in this case, we see that performing a Sort() on the List<T> after every Add() is killing our performance! Of course, this was a very contrived, duh moment, but you’d be surprised how many performance issues become duh moments. Note that this one line is taking up 86% of the execution time of this application! If we eliminate this bottleneck, we should see drastic improvement in the performance. So to fix this, if we still wanted to maintain the List<T> we’d have many options, including: delay Sort() until after all Add() methods, using a SortedSet, SortedList, or SortedDictionary depending on which is most appropriate, or forgoing the sorting all together and using a Dictionary. Rinse, Repeat! So let’s just change all instances of List<string> to SortedSet<string> and run this again through the profiler: Now we see the AddToList() method is no longer our hot-spot, but now the Max() and Min() calls are! This is good because we’ve eliminated one hot-spot and now we can try to correct this one as well. As before, we can then optimize this part of the code (possibly by taking advantage of the fact the list is now sorted and returning the first and last elements). We can then rinse and repeat this process until we have eliminated as many bottlenecks as possible. Calls by Web Request Another feature that was added recently is the ability to view .NET methods grouped by the HTTP requests that caused them to run. This can be helpful in determining which pages, web services, etc. are causing hot spots in your web applications. Summary If you like the other ANTS tools, you’ll like the ANTS Performance Profiler as well. It is extremely easy to use with very little product knowledge required to get up and running. There are profilers built into the higher product lines of Visual Studio, of course, which are also powerful and easy to use. But for quickly jumping in and finding hot spots rapidly, Red Gate’s Performance Profiler 7.4 is an excellent choice. Technorati Tags: Influencers,ANTS,Performance Profiler,Profiler

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• SEO question, getting info about websites

  - by michael

  I don't know much about SEO. I have a csv file with 200,000 links to websites i want to add another field (or maybe couple of them) to each link in the csv file with page ranking of each link and maybe other interesting metrics and info about the link. I saw a free API from http://apiwiki.seomoz.org/ i can maybe use to build a simple script, but it's limited to 3 links for second which will roughly take 1100 minutes or 18 hours to run any other ideas how to get this kind of simple metrics about each link ? thanks !

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• Parsing Extended Events xml_deadlock_report

  - by Michael Zilberstein

  Jonathan Kehayias and Paul Randall posted more than a year ago great articles on how to monitor historical deadlocks using Extended Events system_health default trace. Both tried to fix on the fly the bug in xml output that caused failures in xml validation. Today I've found out that their version isn't bulletproof either. So here is the fixed one: SELECT CAST ( xest.target_data as XML ) xml_data , * INTO #ring_buffer_data FROM     sys.dm_xe_session_targets xest    INNER...(read more)

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• Cut Caseload Costs, Speed Service Delivery For Social Services

  - by michael.seback

  Lower Caseload Costs, Speedier Service Delivery with New Oracle Social Services Solution Oracle has just introduced a new solution for social services agencies that's designed to help case workers address the challenges of rising workloads and growing demands by citizens for additional services. In the past, IT departments developed custom software in an effort to meet program outcomes. "Because this capability is out of the box with the Oracle solution, there's less complexity for organizations and an overall lower total cost of ownership," says Kimberly Ellison-Taylor, Oracle's executive director of health and human services. "Self service brings costs down to just pennies per interaction and makes it possible for clients to receive government services more quickly," Ellison-Taylor says. read more

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• Using Web Services from an XNA 4.0 WP7 Game

  - by Michael Cummings

  Now that the Windows Phone 7 development tools have been out for a while, let’s talk about how you can use them. Windows Phone 7 ( WP7 ) has two application types that you can create, either Silverlight or XNA, and you can’t really mix the two together. The development environment for WP7 is a special edition of Visual Studio 2010 called Visual Studio 2010 Express for Windows Phone. This edition will be installed with the WP7 tools, even if you have a full edition of VS2010 already installed. While you can use your full edition of VS2010 to do WP7 development, this astute developer has noticed that there are a few things that you can only do in the Express for Windows Phone edition. So lets start by discussing WP7 networking. On the WP7 platform the only networking available is through Web Services using WCF or if you’re really masochistic, you’ll use the WebClient to do http. In Silverlight, it’s fairly easy to wire up a WCF proxy to call a web service and get some data. In the XNA projects, not so much. Create WCF Service First, we’ll create our service that will return some information that we need in our game. Open Visual Studio 2010, and create a new WCF Web Service project. We’ll use the default implementation as we only need to see how to use a service, we are not interested in creating a really cool service at this point. However you may want to follow the instructions in the comments of Service1.svc.cs to change the name to something better, I used DataService and IDataService for the interface. You should now be able to run the project and the WCF Test Client will load and properly enumerate your service. At this point we have a functional service that can be consumed by our XNA game. Consume the WCF Service Open Visual Studio 2010 Express for Windows Phone and create a new XNA Game Studio 4.0 Windows Phone Game project. Now if you try to add a service reference to the project, you’ll notice that the option is not available. However, if you add a Silverlight application to your solution, you’ll notice that you can create a service reference there. So using the Silverlight project, we can create the service reference. Unfortunately you can’t reference the Silverlight project from the XNA Game project, so using Windows Explorer copy the Service References folder from the Silverlight project directory to the XNA Game project directory, then add the folder to your XNA Game project. You’ll need to set the property Build Action to None for all the files, except for Reference.cs, which should be Build. Truely, we only need Reference.cs but I find it easier to copy the whole folder. If you try to compile at this point, you’ll notice that we are missing  a couple of references, System.Runtime.Serialization, System.Net and System.ServiceModel. Add these to the XNA Game project and you should build successfully. You’ll also need to copy the ServiceReference.ClientConfig file and add it to your project. The WCF infrastructure looks for this file and will complain if it can’t find it. You’ll need to set the Copy to Output Directory property to Copy if Newer. We now need to add the code to call the service and display the results on the screen. Go ahead and add a SpriteFont resource to the Content project and load it in the Game project. There’s nothing here that’s changed much from 3.1 other than your Content project is now under the Solution node and not the Project node. While you’re at it, add a string field to store the result of the service call, and intialize it to string.Empty. Then in the Draw method, write the string out to the screen, only if it does not equal string.Empty. Now to wrap this up, lets create a new field that’s of the type DataServiceClient. In the Initialize Method, create a new instance of this type using its default contructor, then in the LoadContent we can call the service. Since we can only call the GetData method of our service asynchronously we need to set up a Completed event handler first. Thankfully, Visual Studio helps out a lot there just create, using the tab key whatever VS says to. In the GetDataAsyncCompleted event handler assign the service result ( e.Result) to your string field. If you run your game, you should get something like this : Enjoy!

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• The Evolution of an Era: Customer Experience in Retail

  - by Michael Hylton

  Two New Studies Point to the Direction Retailers are Taking in their CX Initiatives. Is it the Right Direction? The sheer velocity of change in retailing and customer behavior is forcing retailers to reinvigorate, expand and sharpen their vital Customer Experience (CX) strategies. Customers are becoming increasingly dynamic as they race to embrace the newest digital channels; shop in new ways on mobile devices, including smartphones and tablets, on the Web and in the store; share experiences socially; and interact with their preferred brands in new ways. Retailers are stepping up to their customers as they and their competitors create new modes of customer interaction. Underpinning these changes are vast quantities of customer data as customers flood digital channels and the social sphere. The informed retailer must now understand what their priorities are and what they should be for the future. To better understand this, Tata Consultancy Services (TCS) and Oracle independently launched CX-focused surveys to uncover what retailing leadership found important today. By comparing the results of these two studies together, we can further discover new insights about the industry. Click here to download this informative white paper.

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• Oracle Delivers Oracle Social Services Suite

  - by michael.seback

  Oracle Delivers Oracle Social Services Suite with New Releases of Siebel CRM Public Sector 8.2 and Oracle Policy Automation 10 Continuing its leadership and commitment to provide key innovations specifically created for social services agencies, Oracle today released the new Oracle Social Services Suite that includes updated versions of Oracle's Siebel CRM Public Sector 8.2 and Oracle Policy Automation 10. "Oracle's commitment to our social services customers is indisputable with the introduction of Oracle Social Services Suite and the latest innovations from Oracle's Siebel CRM Public Sector 8.2 and Oracle Policy Automation 10," said Anthony Lye, Senior Vice President of CRM, Oracle. "Social service agencies have not only many of the most complex jobs to perform with limited time and funding, but also some of the most important for our society, especially when children are involved. The technology advances Oracle provides will help these agencies increase their own efficiency and save costs, while helping to improve the outcome for their clients." read more

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• C#: Adding Functionality to 3rd Party Libraries With Extension Methods

  - by James Michael Hare

  Ever have one of those third party libraries that you love but it's missing that one feature or one piece of syntactical candy that would make it so much more useful?  This, I truly think, is one of the best uses of extension methods.  I began discussing extension methods in my last post (which you find here) where I expounded upon what I thought were some rules of thumb for using extension methods correctly.  As long as you keep in line with those (or similar) rules, they can often be useful for adding that little extra functionality or syntactical simplification for a library that you have little or no control over. Oh sure, you could take an open source project, download the source and add the methods you want, but then every time the library is updated you have to re-add your changes, which can be cumbersome and error prone.  And yes, you could possibly extend a class in a third party library and override features, but that's only if the class is not sealed, static, or constructed via factories. This is the perfect place to use an extension method!  And the best part is, you and your development team don't need to change anything!  Simply add the using for the namespace the extensions are in! So let's consider this example.  I love log4net!  Of all the logging libraries I've played with, it, to me, is one of the most flexible and configurable logging libraries and it performs great.  But this isn't about log4net, well, not directly.  So why would I want to add functionality?  Well, it's missing one thing I really want in the ILog interface: ability to specify logging level at runtime. For example, let's say I declare my ILog instance like so:     using log4net;     public class LoggingTest     {         private static readonly ILog _log = LogManager.GetLogger(typeof(LoggingTest));         ...     }     If you don't know log4net, the details aren't important, just to show that the field _log is the logger I have gotten from log4net. So now that I have that, I can log to it like so:     _log.Debug("This is the lowest level of logging and just for debugging output.");     _log.Info("This is an informational message.  Usual normal operation events.");     _log.Warn("This is a warning, something suspect but not necessarily wrong.");     _log.Error("This is an error, some sort of processing problem has happened.");     _log.Fatal("Fatals usually indicate the program is dying hideously."); And there's many flavors of each of these to log using string formatting, to log exceptions, etc.  But one thing there isn't: the ability to easily choose the logging level at runtime.  Notice, the logging levels above are chosen at compile time.  Of course, you could do some fun stuff with lambdas and wrap it, but that would obscure the simplicity of the interface.  And yes there is a Logger property you can dive down into where you can specify a Level, but the Level properties don't really match the ILog interface exactly and then you have to manually build a LogEvent and... well, it gets messy.  I want something simple and sexy so I can say:     _log.Log(someLevel, "This will be logged at whatever level I choose at runtime!");     Now, some purists out there might say you should always know what level you want to log at, and for the most part I agree with them.  For the most party the ILog interface satisfies 99% of my needs.  In fact, for most application logging yes you do always know the level you will be logging at, but when writing a utility class, you may not always know what level your user wants. I'll tell you, one of my favorite things is to write reusable components.  If I had my druthers I'd write framework libraries and shared components all day!  And being able to easily log at a runtime-chosen level is a big need for me.  After all, if I want my code to really be re-usable, I shouldn't force a user to deal with the logging level I choose. One of my favorite uses for this is in Interceptors -- I'll describe Interceptors in my next post and some of my favorites -- for now just know that an Interceptor wraps a class and allows you to add functionality to an existing method without changing it's signature.  At the risk of over-simplifying, it's a very generic implementation of the Decorator design pattern. So, say for example that you were writing an Interceptor that would time method calls and emit a log message if the method call execution time took beyond a certain threshold of time.  For instance, maybe if your database calls take more than 5,000 ms, you want to log a warning.  Or if a web method call takes over 1,000 ms, you want to log an informational message.  This would be an excellent use of logging at a generic level. So here was my personal wish-list of requirements for my task: Be able to determine if a runtime-specified logging level is enabled. Be able to log generically at a runtime-specified logging level. Have the same look-and-feel of the existing Debug, Info, Warn, Error, and Fatal calls.    Having the ability to also determine if logging for a level is on at runtime is also important so you don't spend time building a potentially expensive logging message if that level is off.  Consider an Interceptor that may log parameters on entrance to the method.  If you choose to log those parameter at DEBUG level and if DEBUG is not on, you don't want to spend the time serializing those parameters. Now, mine may not be the most elegant solution, but it performs really well since the enum I provide all uses contiguous values -- while it's never guaranteed, contiguous switch values usually get compiled into a jump table in IL which is VERY performant - O(1) - but even if it doesn't, it's still so fast you'd never need to worry about it. So first, I need a way to let users pass in logging levels.  Sure, log4net has a Level class, but it's a class with static members and plus it provides way too many options compared to ILog interface itself -- and wouldn't perform as well in my level-check -- so I define an enum like below.     namespace Shared.Logging.Extensions     {         // enum to specify available logging levels.         public enum LoggingLevel         {             Debug,             Informational,             Warning,             Error,             Fatal         }     } Now, once I have this, writing the extension methods I need is trivial.  Once again, I would typically /// comment fully, but I'm eliminating for blogging brevity:     namespace Shared.Logging.Extensions     {         // the extension methods to add functionality to the ILog interface         public static class LogExtensions         {             // Determines if logging is enabled at a given level.             public static bool IsLogEnabled(this ILog logger, LoggingLevel level)             {                 switch (level)                 {                     case LoggingLevel.Debug:                         return logger.IsDebugEnabled;                     case LoggingLevel.Informational:                         return logger.IsInfoEnabled;                     case LoggingLevel.Warning:                         return logger.IsWarnEnabled;                     case LoggingLevel.Error:                         return logger.IsErrorEnabled;                     case LoggingLevel.Fatal:                         return logger.IsFatalEnabled;                 }                                 return false;             }             // Logs a simple message - uses same signature except adds LoggingLevel             public static void Log(this ILog logger, LoggingLevel level, object message)             {                 switch (level)                 {                     case LoggingLevel.Debug:                         logger.Debug(message);                         break;                     case LoggingLevel.Informational:                         logger.Info(message);                         break;                     case LoggingLevel.Warning:                         logger.Warn(message);                         break;                     case LoggingLevel.Error:                         logger.Error(message);                         break;                     case LoggingLevel.Fatal:                         logger.Fatal(message);                         break;                 }             }             // Logs a message and exception to the log at specified level.             public static void Log(this ILog logger, LoggingLevel level, object message, Exception exception)             {                 switch (level)                 {                     case LoggingLevel.Debug:                         logger.Debug(message, exception);                         break;                     case LoggingLevel.Informational:                         logger.Info(message, exception);                         break;                     case LoggingLevel.Warning:                         logger.Warn(message, exception);                         break;                     case LoggingLevel.Error:                         logger.Error(message, exception);                         break;                     case LoggingLevel.Fatal:                         logger.Fatal(message, exception);                         break;                 }             }             // Logs a formatted message to the log at the specified level.              public static void LogFormat(this ILog logger, LoggingLevel level, string format,                                          params object[] args)             {                 switch (level)                 {                     case LoggingLevel.Debug:                         logger.DebugFormat(format, args);                         break;                     case LoggingLevel.Informational:                         logger.InfoFormat(format, args);                         break;                     case LoggingLevel.Warning:                         logger.WarnFormat(format, args);                         break;                     case LoggingLevel.Error:                         logger.ErrorFormat(format, args);                         break;                     case LoggingLevel.Fatal:                         logger.FatalFormat(format, args);                         break;                 }             }         }     } So there it is!  I didn't have to modify the log4net source code, so if a new version comes out, i can just add the new assembly with no changes.  I didn't have to subclass and worry about developers not calling my sub-class instead of the original.  I simply provide the extension methods and it's as if the long lost extension methods were always a part of the ILog interface! Consider a very contrived example using the original interface:     // using the original ILog interface     public class DatabaseUtility     {         private static readonly ILog _log = LogManager.Create(typeof(DatabaseUtility));                 // some theoretical method to time         IDataReader Execute(string statement)         {             var timer = new System.Diagnostics.Stopwatch();                         // do DB magic                                    // this is hard-coded to warn, if want to change at runtime tough luck!             if (timer.ElapsedMilliseconds > 5000 && _log.IsWarnEnabled)             {                 _log.WarnFormat("Statement {0} took too long to execute.", statement);             }             ...         }     }     Now consider this alternate call where the logging level could be perhaps a property of the class          // using the original ILog interface     public class DatabaseUtility     {         private static readonly ILog _log = LogManager.Create(typeof(DatabaseUtility));                 // allow logging level to be specified by user of class instead         public LoggingLevel ThresholdLogLevel { get; set; }                 // some theoretical method to time         IDataReader Execute(string statement)         {             var timer = new System.Diagnostics.Stopwatch();                         // do DB magic                                    // this is hard-coded to warn, if want to change at runtime tough luck!             if (timer.ElapsedMilliseconds > 5000 && _log.IsLogEnabled(ThresholdLogLevel))             {                 _log.LogFormat(ThresholdLogLevel, "Statement {0} took too long to execute.",                     statement);             }             ...         }     } Next time, I'll show one of my favorite uses for these extension methods in an Interceptor.

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• C# tip: do not use “is” type, if you will need cast “as” later

  - by Michael Freidgeim

  We have a debate with one of my collegues, is it agood style to check, if the object of particular style, and then cast  as this  type. The perfect answer of Jon Skeet   and answers in Cast then check or check then cast? confirmed my point.//good    var coke = cola as CocaCola;    if (coke != null)    {        // some unique coca-cola only code    }    //worse    if (cola is CocaCola)    {        var coke =  cola as CocaCola;        // some unique coca-cola only code here.    }

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• Red Gate Coder interviews: Robin Hellen

  - by Michael Williamson

  Robin Hellen is a test engineer here at Red Gate, and is also the latest coder I’ve interviewed. We chatted about debugging code, the roles of software engineers and testers, and why Vala is currently his favourite programming language. How did you get started with programming?It started when I was about six. My dad’s a professional programmer, and he gave me and my sister one of his old computers and taught us a bit about programming. It was an old Amiga 500 with a variant of BASIC. I don’t think I ever successfully completed anything! It was just faffing around. I didn’t really get anywhere with it.But then presumably you did get somewhere with it at some point.At some point. The PC emerged as the dominant platform, and I learnt a bit of Visual Basic. I didn’t really do much, just a couple of quick hacky things. A bit of demo animation. Took me a long time to get anywhere with programming, really.When did you feel like you did start to get somewhere?I think it was when I started doing things for someone else, which was my sister’s final year of university project. She called up my dad two days before she was due to submit, saying “We need something to display a graph!”. Dad says, “I’m too busy, go talk to your brother”. So I hacked up this ugly piece of code, sent it off and they won a prize for that project. Apparently, the graph, the bit that I wrote, was the reason they won a prize! That was when I first felt that I’d actually done something that was worthwhile. That was my first real bit of code, and the ugliest code I’ve ever written. It’s basically an array of pre-drawn line elements that I shifted round the screen to draw a very spikey graph.When did you decide that programming might actually be something that you wanted to do as a career?It’s not really a decision I took, I always wanted to do something with computers. And I had to take a gap year for uni, so I was looking for twelve month internships. I applied to Red Gate, and they gave me a job as a tester. And that’s where I really started having to write code well. To a better standard that I had been up to that point.How did you find coming to Red Gate and working with other coders?I thought it was really nice. I learnt so much just from other people around. I think one of the things that’s really great is that people are just willing to help you learn. Instead of “Don’t you know that, you’re so stupid”, it’s “You can just do it this way”.If you could go back to the very start of that internship, is there something that you would tell yourself?Write shorter code. I have a tendency to write massive, many-thousand line files that I break out of right at the end. And then half-way through a project I’m doing something, I think “Where did I write that bit that does that thing?”, and it’s almost impossible to find. I wrote some horrendous code when I started. Just that principle, just keep things short. Even if looks a bit crazy to be jumping around all over the place all of the time, it’s actually a lot more understandable.And how do you hold yourself to that?Generally, if a function’s going off my screen, it’s probably too long. That’s what I tell myself, and within the team here we have code reviews, so the guys I’m with at the moment are pretty good at pulling me up on, “Doesn’t that look like it’s getting a bit long?”. It’s more just the subjective standard of readability than anything.So you’re an advocate of code review?Yes, definitely. Both to spot errors that you might have made, and to improve your knowledge. The person you’re reviewing will say “Oh, you could have done it that way”. That’s how we learn, by talking to others, and also just sharing knowledge of how your project works around the team, or even outside the team. Definitely a very firm advocate of code reviews.Do you think there’s more we could do with them?I don’t know. We’re struggling with how to add them as part of the process without it becoming too cumbersome. We’ve experimented with a few different ways, and we’ve not found anything that just works.To get more into the nitty gritty: how do you like to debug code?The first thing is to do it in my head. I’ll actually think what piece of code is likely to have caused that error, and take a quick look at it, just to see if there’s anything glaringly obvious there. The next thing I’ll probably do is throw in print statements, or throw some exceptions from various points, just to check: is it going through the code path I expect it to? A last resort is to actually debug code using a debugger.Why is the debugger the last resort?Probably because of the environments I learnt programming in. VB and early BASIC didn’t have much of a debugger, the only way to find out what your program was doing was to add print statements. Also, because a lot of the stuff I tend to work with is non-interactive, if it’s something that takes a long time to run, I can throw in the print statements, set a run off, go and do something else, and look at it again later, rather than trying to remember what happened at that point when I was debugging through it. So it also gives me the record of what happens. I hate just sitting there pressing F5, F5, continually. If you’re having to find out what your code is doing at each line, you’ve probably got a very wrong mental model of what your code’s doing, and you can find that out just as easily by inspecting a couple of values through the print statements.If I were on some codebase that you were also working on, what should I do to make it as easy as possible to understand?I’d say short and well-named methods. The one thing I like to do when I’m looking at code is to find out where a value comes from, and the more layers of indirection there are, particularly DI [dependency injection] frameworks, the harder it is to find out where something’s come from. I really hate that. I want to know if the value come from the user here or is a constant here, and if I can’t find that out, that makes code very hard to understand for me.As a tester, where do you think the split should lie between software engineers and testers?I think the split is less on areas of the code you write and more what you’re designing and creating. The developers put a structure on the code, while my major role is to say which tests we should have, whether we should test that, or it’s not worth testing that because it’s a tiny function in code that nobody’s ever actually going to see. So it’s not a split in the code, it’s a split in what you’re thinking about. Saying what code we should write, but alternatively what code we should take out.In your experience, do the software engineers tend to do much testing themselves?They tend to control the lowest layer of tests. And, depending on how the balance of people is in the team, they might write some of the higher levels of test. Or that might go to the testers. I’m the only tester on my team with three other developers, so they’ll be writing quite a lot of the actual test code, with input from me as to whether we should test that functionality, whereas on other teams, where it’s been more equal numbers, the testers have written pretty much all of the high level tests, just because that’s the best use of resource.If you could shuffle resources around however you liked, do you think that the developers should be writing those high-level tests?I think they should be writing them occasionally. It helps when they have an understanding of how testing code works and possibly what assumptions we’ve made in tests, and they can say “actually, it doesn’t work like that under the hood so you’ve missed this whole area”. It’s one of those agile things that everyone on the team should be at least comfortable doing the various jobs. So if the developers can write test code then I think that’s a very good thing.So you think testers should be able to write production code?Yes, although given most testers skills at coding, I wouldn’t advise it too much! I have written a few things, and I did make a few changes that have actually gone into our production code base. They’re not necessarily running every time but they are there. I think having that mix of skill sets is really useful. In some ways we’re using our own product to test itself, so being able to make those changes where it’s not working saves me a round-trip through the developers. It can be really annoying if the developers have no time to make a change, and I can’t touch the code.If the software engineers are consistently writing tests at all levels, what role do you think the role of a tester is?I think on a team like that, those distinctions aren’t quite so useful. There’ll be two cases. There’s either the case where the developers think they’ve written good tests, but you still need someone with a test engineer mind-set to go through the tests and validate that it’s a useful set, or the correct set for that code. Or they won’t actually be pure developers, they’ll have that mix of test ability in there.I think having slightly more distinct roles is useful. When it starts to blur, then you lose that view of the tests as a whole. The tester job is not to create tests, it’s to validate the quality of the product, and you don’t do that just by writing tests. There’s more things you’ve got to keep in your mind. And I think when you blur the roles, you start to lose that end of the tester.So because you’re working on those features, you lose that holistic view of the whole system?Yeah, and anyone who’s worked on the feature shouldn’t be testing it. You always need to have it tested it by someone who didn’t write it. Otherwise you’re a bit too close and you assume “yes, people will only use it that way”, but the tester will come along and go “how do people use this? How would our most idiotic user use this?”. I might not test that because it might be completely irrelevant. But it’s coming in and trying to have a different set of assumptions.Are you a believer that it should all be automated if possible?Not entirely. So an automated test is always better than a manual test for the long-term, but there’s still nothing that beats a human sitting in front of the application and thinking “What could I do at this point?”. The automated test is very good but they follow that strict path, and they never check anything off the path. The human tester will look at things that they weren’t expecting, whereas the automated test can only ever go “Is that value correct?” in many respects, and it won’t notice that on the other side of the screen you’re showing something completely wrong. And that value might have been checked independently, but you always find a few odd interactions when you’re going through something manually, and you always need to go through something manually to start with anyway, otherwise you won’t know where the important bits to write your automation are.When you’re doing that manual testing, do you think it’s important to do that across the entire product, or just the bits that you’ve touched recently?I think it’s important to do it mostly on the bits you’ve touched, but you can’t ignore the rest of the product. Unless you’re dealing with a very, very self-contained bit, you’re almost always encounter other bits of the product along the way. Most testers I know, even if they are looking at just one path, they’ll keep open and move around a bit anyway, just because they want to find something that’s broken. If we find that your path is right, we’ll go out and hunt something else.How do you think this fits into the idea of continuously deploying, so long as the tests pass?With deploying a website it’s a bit different because you can always pull it back. If you’re deploying an application to customers, when you’ve released it, it’s out there, you can’t pull it back. Someone’s going to keep it, no matter how hard you try there will be a few installations that stay around. So I’d always have at least a human element on that path. With websites, you could probably automate straight out, or at least straight out to an internal environment or a single server in a cloud of fifty that will serve some people. But I don’t think you should release to everyone just on automated tests passing.You’ve already mentioned using BASIC and C# — are there any other languages that you’ve used?I’ve used a few. That’s something that has changed more recently, I’ve become familiar with more languages. Before I started at Red Gate I learnt a bit of C. Then last year, I taught myself Python which I actually really enjoyed using. I’ve also come across another language called Vala, which is sort of a C#-like language. It’s basically a pre-processor for C, but it has very nice syntax. I think that’s currently my favourite language.Any particular reason for trying Vala?I have a completely Linux environment at home, and I’ve been looking for a nice language, and C# just doesn’t cut it because I won’t touch Mono. So, I was looking for something like C# but that was useable in an open source environment, and Vala’s what I found. C#’s got a few features that Vala doesn’t, and Vala’s got a few features where I think “It would be awesome if C# had that”.What are some of the features that it’s missing?Extension methods. And I think that’s the only one that really bugs me. I like to use them when I’m writing C# because it makes some things really easy, especially with libraries that you can’t touch the internals of. It doesn’t have method overloading, which is sometimes annoying.Where it does win over C#?Everything is non-nullable by default, you never have to check that something’s unexpectedly null.Also, Vala has code contracts. This is starting to come in C# 4, but the way it works in Vala is that you specify requirements in short phrases as part of your function signature and they stick to the signature, so that when you inherit it, it has exactly the same code contract as the base one, or when you inherit from an interface, you have to match the signature exactly. Just using those makes you think a bit more about how you’re writing your method, it’s not an afterthought when you’ve got contracts from base classes given to you, you can’t change it. Which I think is a lot nicer than the way C# handles it. When are those actually checked?They’re checked both at compile and run-time. The compile-time checking isn’t very strong yet, it’s quite a new feature in the compiler, and because it compiles down to C, you can write C code and interface with your methods, so you can bypass that compile-time check anyway. So there’s an extra runtime check, and if you violate one of the contracts at runtime, it’s game over for your program, there’s no exception to catch, it’s just goodbye!One thing I dislike about C# is the exceptions. You write a bit of code and fifty exceptions could come from any point in your ten lines, and you can’t mentally model how those exceptions are going to come out, and you can’t even predict them based on the functions you’re calling, because if you’ve accidentally got a derived class there instead of a base class, that can throw a completely different set of exceptions. So I’ve got no way of mentally modelling those, whereas in Vala they’re checked like Java, so you know only these exceptions can come out. You know in advance the error conditions.I think Raymond Chen on Old New Thing says “the only thing you know when you throw an exception is that you’re in an invalid state somewhere in your program, so just kill it and be done with it!”You said you’ve also learnt bits of Python. How did you find that compared to Vala and C#?Very different because of the dynamic typing. I’ve been writing a website for my own use. I’m quite into photography, so I take photos off my camera, post-process them, dump them in a file, and I get a webpage with all my thumbnails. So sort of like Picassa, but written by myself because I wanted something to learn Python with. There are some things that are really nice, I just found it really difficult to cope with the fact that I’m not quite sure what this object type that I’m passed is, I might not ever be sure, so it can randomly blow up on me. But once I train myself to ignore that and just say “well, I’m fairly sure it’s going to be something that looks like this, so I’ll use it like this”, then it’s quite nice.Any particular features that you’ve appreciated?I don’t like any particular feature, it’s just very straightforward to work with. It’s very quick to write something in, particularly as you don’t have to worry that you’ve changed something that affects a different part of the program. If you have, then that part blows up, but I can get this part working right now.If you were doing a big project, would you be willing to do it in Python rather than C# or Vala?I think I might be willing to try something bigger or long term with Python. We’re currently doing an ASP.NET MVC project on C#, and I don’t like the amount of reflection. There’s a lot of magic that pulls values out, and it’s all done under the scenes. It’s almost managed to put a dynamic type system on top of C#, which in many ways destroys the language to me, whereas if you’re already in a dynamic language, having things done dynamically is much more natural. In many ways, you get the worst of both worlds. I think for web projects, I would go with Python again, whereas for anything desktop, command-line or GUI-based, I’d probably go for C# or Vala, depending on what environment I’m in.It’s the fact that you can gain from the strong typing in ways that you can’t so much on the web app. Or, in a web app, you have to use dynamic typing at some point, or you have to write a hell of a lot of boilerplate, and I’d rather use the dynamic typing than write the boilerplate.What do you think separates great programmers from everyone else?Probably design choices. Choosing to write it a piece of code one way or another. For any given program you ask me to write, I could probably do it five thousand ways. A programmer who is capable will see four or five of them, and choose one of the better ones. The excellent programmer will see the largest proportion and manage to pick the best one very quickly without having to think too much about it. I think that’s probably what separates, is the speed at which they can see what’s the best path to write the program in. More Red Gater Coder interviews

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• NServiceBus Generic Host and mqsvc.exe high CPU

  - by Michael Stephenson

  We have been doing some work with NServiceBus recently and observed some unusual behaviour which was caused by our mistake and seemed worthy of a small post.   The Scenario In our solution we were doing some standard NServiceBus stuff by pushing a message to a queue using NServiceBus.  We had a direct send/receive scenario rather than a publish/subscribe one.   The background process which was meant to collect the message and then process it was a normal NServiceBus message handler.  We would run the NServiceBus.Host.exe which would find the handler and then do the usual NServiceBus magic.   The Problem In this solution we were creating some automated tests around this module of the integration process to ensure that it would work well.  We had two tests.   Test 1 This test would start NServiceBus.Host.exe using the Process object, then seed a message to the queue via our web service façade sitting above the queue which wrapped NServiceBus.  The background process would then process the message and the test would check the message had been processed fine.   If all was well then the NServiceBus.Host.exe process was stopped.   Test 2 In test 2 we would do a very similar thing except that instead of starting the process the test would install NServiceBus.Host.exe as a windows service and then start the service before the test and once the test was executed it would stop the test.   The Results of the Tests Test 1 worked really well, however in test 2 we found that it didn’t really work at all, instead of doing the background process we were finding that between mqsvc.exe and NServiceBus.Host.exe the CPU on the machine was maxed and nothing was really happening.   The Solution After trying a few things we found it was the permissions on the queue were not set correctly.  Once this was resolved it all worked fine and CPU was not excessive and ran just like the console application.   I think the couple of take aways from this are:   Make sure you set the windows service for NserviceBus Generic Host to the right credentials When you install the generic host as a windows service then by default it will use the default windows credentials.  For any production like scenario you should be using a domain account to run the process as via the windows service. Make sure you have the queue set with the right permissions For the credentials you have used to configure the generic host as a windows service you should ensure that this user has the appropriate permissions for any queues it will interact with. Make sure you turn on the right logging configuration in NServiceBus When this wasnt working correctly we didnt know there was an issue, we were just experiencing the high CPU condition.  I am a little surprised that there wasnt something logged and that the process didnt crash.  I guess this could be by design bearing in mind that the process could be monitoring many queues.  In this point Im just saying that originally we didnt have all of the log4net logging which is available from NServiceBus turned on.  Its probably a good idea to have this turned on and configured until you are happy your solution is working fine.   Thanks to Ahmed Hashmi on my team who got this working in the end.

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• Using NServiceBus behind a custom web service

  - by Michael Stephenson

  In this post I'd like to talk about an architecture scenario we had recently and how we were able to utilise NServiceBus to help us address this problem. Scenario Cognos is a reporting system used by one of my clients. A while back we developed a web service façade to allow line of business applications to be able to access reports from Cognos to support their various functions. The service was intended to provide access to reports which were quick running reports or pre-generated reports which could be accessed real-time on demand. One of the key aims of the web service was to provide a simple generic interface to allow applications to get any report without needing to worry about the complex .net SDK for Cognos. The web service also supported multi-hop kerberos delegation so that report data could be accesses under the context of the end user. This service was working well for a period of time. The Problem The problem we encountered was that reports were now also required to be available to batch processes. The original design was optimised for low latency so users would enjoy a positive experience, however when the batch processes started to request 250+ concurrent reports over an extended period of time you can begin to imagine the sorts of problems that come into play. The key problems this new scenario caused are: Users may be affected and the latency of on demand reports was significantly slower The Cognos infrastructure was not scaled sufficiently to be able to cope with these long peaks of load From a cost perspective it just isn't feasible to scale the Cognos infrastructure to be able to handle the load when it is only for a couple of hour window each night. We really needed to introduce a second pattern for accessing this service which would support high through-put scenarios. We also had little control over the batch process in terms of being able to throttle its load. We could however make some changes to the way it accessed the reports. The Approach My idea was to introduce a throttling mechanism between the Web Service Façade and Cognos. This would allow the batch processes to push reports requests hard at the web service which we were confident the web service can handle. The web service would then queue these requests and process them behind the scenes and make a call back to the batch application to provide the report once it had been accessed. In terms of technology we had some limitations because we were not able to use WCF or IIS7 where the MSMQ-Activated WCF services could have helped, but we did have MSMQ as an option and I thought NServiceBus could do just the job to help us here. The flow of how this would work was as follows: The batch applications would send a request for a report to the web service The web service uses NServiceBus to send the message to a Queue The NServiceBus Generic Host is running as a windows service with a message handler which subscribes to these messages The message handler gets the message, accesses the report from Cognos The message handler calls back to the original batch application, this is decoupled because the calling application provides a call back url The report gets into the batch application and is processed as normal This approach looks something like the below diagram: The key points are an application wanting to take advantage of the batch driven reports needs to do the following: Implement our call back contract Make a call to the service providing a call back url Provide a correlation ID so it knows how to tie each response back to its request What does NServiceBus offer in this solution So this scenario is not the typical messaging service bus type of solution people implement with NServiceBus, but it did offer the following: Simplified interaction with MSMQ Offered the ability to configure the number of processes working through the queue so we could find a balance between load on Cognos versus the applications end to end processing time NServiceBus offers retries and a way to manage failed messages NServiceBus offers a high availability setup The simple thing is that NServiceBus gave us the platform to build the solution on. We just implemented a message handler which functionally processed a message and we could rely on NServiceBus to do all of the hard work around managing the queues and all of the lower level things that would have took ages to write to any kind of robust level. Conclusion With this approach we were able to deal with a fairly significant performance issue with out too much rework. Hopefully this write up gives people some insight into ideas on how to leverage the excellent NServiceBus framework to help solve integration and high through-put scenarios.

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• C#/.NET Little Wonders: The Joy of Anonymous Types

  - by James Michael Hare

  Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the .NET 3 Framework, Microsoft introduced the concept of anonymous types, which provide a way to create a quick, compiler-generated types at the point of instantiation.  These may seem trivial, but are very handy for concisely creating lightweight, strongly-typed objects containing only read-only properties that can be used within a given scope. Creating an Anonymous Type In short, an anonymous type is a reference type that derives directly from object and is defined by its set of properties base on their names, number, types, and order given at initialization.  In addition to just holding these properties, it is also given appropriate overridden implementations for Equals() and GetHashCode() that take into account all of the properties to correctly perform property comparisons and hashing.  Also overridden is an implementation of ToString() which makes it easy to display the contents of an anonymous type instance in a fairly concise manner. To construct an anonymous type instance, you use basically the same initialization syntax as with a regular type.  So, for example, if we wanted to create an anonymous type to represent a particular point, we could do this: 1: var point = new { X = 13, Y = 7 }; Note the similarity between anonymous type initialization and regular initialization.  The main difference is that the compiler generates the type name and the properties (as readonly) based on the names and order provided, and inferring their types from the expressions they are assigned to. It is key to remember that all of those factors (number, names, types, order of properties) determine the anonymous type.  This is important, because while these two instances share the same anonymous type: 1: // same names, types, and order 2: var point1 = new { X = 13, Y = 7 }; 3: var point2 = new { X = 5, Y = 0 }; These similar ones do not: 1: var point3 = new { Y = 3, X = 5 }; // different order 2: var point4 = new { X = 3, Y = 5.0 }; // different type for Y 3: var point5 = new {MyX = 3, MyY = 5 }; // different names 4: var point6 = new { X = 1, Y = 2, Z = 3 }; // different count Limitations on Property Initialization Expressions The expression for a property in an anonymous type initialization cannot be null (though it can evaluate to null) or an anonymous function.  For example, the following are illegal: 1: // Null can't be used directly. Null reference of what type? 2: var cantUseNull = new { Value = null }; 3:  4: // Anonymous methods cannot be used. 5: var cantUseAnonymousFxn = new { Value = () => Console.WriteLine(“Can’t.”) }; Note that the restriction on null is just that you can’t use it directly as the expression, because otherwise how would it be able to determine the type?  You can, however, use it indirectly assigning a null expression such as a typed variable with the value null, or by casting null to a specific type: 1: string str = null; 2: var fineIndirectly = new { Value = str }; 3: var fineCast = new { Value = (string)null }; All of the examples above name the properties explicitly, but you can also implicitly name properties if they are being set from a property, field, or variable.  In these cases, when a field, property, or variable is used alone, and you don’t specify a property name assigned to it, the new property will have the same name.  For example: 1: int variable = 42; 2:  3: // creates two properties named varriable and Now 4: var implicitProperties = new { variable, DateTime.Now }; Is the same type as: 1: var explicitProperties = new { variable = variable, Now = DateTime.Now }; But this only works if you are using an existing field, variable, or property directly as the expression.  If you use a more complex expression then the name cannot be inferred: 1: // can't infer the name variable from variable * 2, must name explicitly 2: var wontWork = new { variable * 2, DateTime.Now }; In the example above, since we typed variable * 2, it is no longer just a variable and thus we would have to assign the property a name explicitly. ToString() on Anonymous Types One of the more trivial overrides that an anonymous type provides you is a ToString() method that prints the value of the anonymous type instance in much the same format as it was initialized (except actual values instead of expressions as appropriate of course). For example, if you had: 1: var point = new { X = 13, Y = 42 }; And then print it out: 1: Console.WriteLine(point.ToString()); You will get: 1: { X = 13, Y = 42 } While this isn’t necessarily the most stunning feature of anonymous types, it can be handy for debugging or logging values in a fairly easy to read format. Comparing Anonymous Type Instances Because anonymous types automatically create appropriate overrides of Equals() and GetHashCode() based on the underlying properties, we can reliably compare two instances or get hash codes.  For example, if we had the following 3 points: 1: var point1 = new { X = 1, Y = 2 }; 2: var point2 = new { X = 1, Y = 2 }; 3: var point3 = new { Y = 2, X = 1 }; If we compare point1 and point2 we’ll see that Equals() returns true because they overridden version of Equals() sees that the types are the same (same number, names, types, and order of properties) and that the values are the same.   In addition, because all equal objects should have the same hash code, we’ll see that the hash codes evaluate to the same as well: 1: // true, same type, same values 2: Console.WriteLine(point1.Equals(point2)); 3:  4: // true, equal anonymous type instances always have same hash code 5: Console.WriteLine(point1.GetHashCode() == point2.GetHashCode()); However, if we compare point2 and point3 we get false.  Even though the names, types, and values of the properties are the same, the order is not, thus they are two different types and cannot be compared (and thus return false).  And, since they are not equal objects (even though they have the same value) there is a good chance their hash codes are different as well (though not guaranteed): 1: // false, different types 2: Console.WriteLine(point2.Equals(point3)); 3:  4: // quite possibly false (was false on my machine) 5: Console.WriteLine(point2.GetHashCode() == point3.GetHashCode()); Using Anonymous Types Now that we’ve created instances of anonymous types, let’s actually use them.  The property names (whether implicit or explicit) are used to access the individual properties of the anonymous type.  The main thing, once again, to keep in mind is that the properties are readonly, so you cannot assign the properties a new value (note: this does not mean that instances referred to by a property are immutable – for more information check out C#/.NET Fundamentals: Returning Data Immutably in a Mutable World). Thus, if we have the following anonymous type instance: 1: var point = new { X = 13, Y = 42 }; We can get the properties as you’d expect: 1: Console.WriteLine(“The point is: ({0},{1})”, point.X, point.Y); But we cannot alter the property values: 1: // compiler error, properties are readonly 2: point.X = 99; Further, since the anonymous type name is only known by the compiler, there is no easy way to pass anonymous type instances outside of a given scope.  The only real choices are to pass them as object or dynamic.  But really that is not the intention of using anonymous types.  If you find yourself needing to pass an anonymous type outside of a given scope, you should really consider making a POCO (Plain Old CLR Type – i.e. a class that contains just properties to hold data with little/no business logic) instead. Given that, why use them at all?  Couldn’t you always just create a POCO to represent every anonymous type you needed?  Sure you could, but then you might litter your solution with many small POCO classes that have very localized uses. It turns out this is the key to when to use anonymous types to your advantage: when you just need a lightweight type in a local context to store intermediate results, consider an anonymous type – but when that result is more long-lived and used outside of the current scope, consider a POCO instead. So what do we mean by intermediate results in a local context?  Well, a classic example would be filtering down results from a LINQ expression.  For example, let’s say we had a List<Transaction>, where Transaction is defined something like: 1: public class Transaction 2: { 3: public string UserId { get; set; } 4: public DateTime At { get; set; } 5: public decimal Amount { get; set; } 6: // … 7: } And let’s say we had this data in our List<Transaction>: 1: var transactions = new List<Transaction> 2: { 3: new Transaction { UserId = "Jim", At = DateTime.Now, Amount = 2200.00m }, 4: new Transaction { UserId = "Jim", At = DateTime.Now, Amount = -1100.00m }, 5: new Transaction { UserId = "Jim", At = DateTime.Now.AddDays(-1), Amount = 900.00m }, 6: new Transaction { UserId = "John", At = DateTime.Now.AddDays(-2), Amount = 300.00m }, 7: new Transaction { UserId = "John", At = DateTime.Now, Amount = -10.00m }, 8: new Transaction { UserId = "Jane", At = DateTime.Now, Amount = 200.00m }, 9: new Transaction { UserId = "Jane", At = DateTime.Now, Amount = -50.00m }, 10: new Transaction { UserId = "Jaime", At = DateTime.Now.AddDays(-3), Amount = -100.00m }, 11: new Transaction { UserId = "Jaime", At = DateTime.Now.AddDays(-3), Amount = 300.00m }, 12: }; So let’s say we wanted to get the transactions for each day for each user.  That is, for each day we’d want to see the transactions each user performed.  We could do this very simply with a nice LINQ expression, without the need of creating any POCOs: 1: // group the transactions based on an anonymous type with properties UserId and Date: 2: byUserAndDay = transactions 3: .GroupBy(tx => new { tx.UserId, tx.At.Date }) 4: .OrderBy(grp => grp.Key.Date) 5: .ThenBy(grp => grp.Key.UserId); Now, those of you who have attempted to use custom classes as a grouping type before (such as GroupBy(), Distinct(), etc.) may have discovered the hard way that LINQ gets a lot of its speed by utilizing not on Equals(), but also GetHashCode() on the type you are grouping by.  Thus, when you use custom types for these purposes, you generally end up having to write custom Equals() and GetHashCode() implementations or you won’t get the results you were expecting (the default implementations of Equals() and GetHashCode() are reference equality and reference identity based respectively). As we said before, it turns out that anonymous types already do these critical overrides for you.  This makes them even more convenient to use!  Instead of creating a small POCO to handle this grouping, and then having to implement a custom Equals() and GetHashCode() every time, we can just take advantage of the fact that anonymous types automatically override these methods with appropriate implementations that take into account the values of all of the properties. Now, we can look at our results: 1: foreach (var group in byUserAndDay) 2: { 3: // the group’s Key is an instance of our anonymous type 4: Console.WriteLine("{0} on {1:MM/dd/yyyy} did:", group.Key.UserId, group.Key.Date); 5:  6: // each grouping contains a sequence of the items. 7: foreach (var tx in group) 8: { 9: Console.WriteLine("\t{0}", tx.Amount); 10: } 11: } And see: 1: Jaime on 06/18/2012 did: 2: -100.00 3: 300.00 4:  5: John on 06/19/2012 did: 6: 300.00 7:  8: Jim on 06/20/2012 did: 9: 900.00 10:  11: Jane on 06/21/2012 did: 12: 200.00 13: -50.00 14:  15: Jim on 06/21/2012 did: 16: 2200.00 17: -1100.00 18:  19: John on 06/21/2012 did: 20: -10.00 Again, sure we could have just built a POCO to do this, given it an appropriate Equals() and GetHashCode() method, but that would have bloated our code with so many extra lines and been more difficult to maintain if the properties change.  Summary Anonymous types are one of those Little Wonders of the .NET language that are perfect at exactly that time when you need a temporary type to hold a set of properties together for an intermediate result.  While they are not very useful beyond the scope in which they are defined, they are excellent in LINQ expressions as a way to create and us intermediary values for further expressions and analysis. Anonymous types are defined by the compiler based on the number, type, names, and order of properties created, and they automatically implement appropriate Equals() and GetHashCode() overrides (as well as ToString()) which makes them ideal for LINQ expressions where you need to create a set of properties to group, evaluate, etc. Technorati Tags: C#,CSharp,.NET,Little Wonders,Anonymous Types,LINQ

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• Ubuntu Software Center does not allow changes to software sources

  - by Michael Goldshteyn

  The checkboxes that appear to be changeable under the Edit / Software Sources dialog box cannot be changed. I click on them and they just turn gray and stay at their current setting. Update: When I run software-center from a terminal window and try to change one of the checkbox settings, I get: Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 649, in on_isv_source_toggled self.backend.ToggleSourceUse(str(source_entry)) File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 143, in __call__ **keywords) File "/usr/lib/python2.7/dist-packages/dbus/connection.py", line 630, in call_blocking message, timeout) dbus.exceptions.DBusException: com.ubuntu.SoftwareProperties.PermissionDeniedByPolicy: com.ubuntu.softwareproperties.applychanges These things happen instead of it properly prompting me for a password (for root privs).

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• C#/.NET Little Pitfalls: The Dangers of Casting Boxed Values

  - by James Michael Hare

  Starting a new series to parallel the Little Wonders series.  In this series, I will examine some of the small pitfalls that can occasionally trip up developers. Introduction: Of Casts and Conversions What happens when we try to assign from an int and a double and vice-versa? 1: double pi = 3.14; 2: int theAnswer = 42; 3:  4: // implicit widening conversion, compiles! 5: double doubleAnswer = theAnswer; 6:  7: // implicit narrowing conversion, compiler error! 8: int intPi = pi; As you can see from the comments above, a conversion from a value type where there is no potential data loss is can be done with an implicit conversion.  However, when converting from one value type to another may result in a loss of data, you must make the conversion explicit so the compiler knows you accept this risk.  That is why the conversion from double to int will not compile with an implicit conversion, we can make the conversion explicit by adding a cast: 1: // explicit narrowing conversion using a cast, compiler 2: // succeeds, but results may have data loss: 3: int intPi = (int)pi; So for value types, the conversions (implicit and explicit) both convert the original value to a new value of the given type.  With widening and narrowing references, however, this is not the case.  Converting reference types is a bit different from converting value types.  First of all when you perform a widening or narrowing you don’t really convert the instance of the object, you just convert the reference itself to the wider or narrower reference type, but both the original and new reference type both refer back to the same object. Secondly, widening and narrowing for reference types refers the going down and up the class hierarchy instead of referring to precision as in value types.  That is, a narrowing conversion for a reference type means you are going down the class hierarchy (for example from Shape to Square) whereas a widening conversion means you are going up the class hierarchy (from Square to Shape).  1: var square = new Square(); 2:  3: // implicitly convers because all squares are shapes 4: // (that is, all subclasses can be referenced by a superclass reference) 5: Shape myShape = square; 6:  7: // implicit conversion not possible, not all shapes are squares! 8: // (that is, not all superclasses can be referenced by a subclass reference) 9: Square mySquare = (Square) myShape; So we had to cast the Shape back to Square because at that point the compiler has no way of knowing until runtime whether the Shape in question is truly a Square.  But, because the compiler knows that it’s possible for a Shape to be a Square, it will compile.  However, if the object referenced by myShape is not truly a Square at runtime, you will get an invalid cast exception. Of course, there are other forms of conversions as well such as user-specified conversions and helper class conversions which are beyond the scope of this post.  The main thing we want to focus on is this seemingly innocuous casting method of widening and narrowing conversions that we come to depend on every day and, in some cases, can bite us if we don’t fully understand what is going on!  The Pitfall: Conversions on Boxed Value Types Can Fail What if you saw the following code and – knowing nothing else – you were asked if it was legal or not, what would you think: 1: // assuming x is defined above this and this 2: // assignment is syntactically legal. 3: x = 3.14; 4:  5: // convert 3.14 to int. 6: int truncated = (int)x; You may think that since x is obviously a double (can’t be a float) because 3.14 is a double literal, but this is inaccurate.  Our x could also be dynamic and this would work as well, or there could be user-defined conversions in play.  But there is another, even simpler option that can often bite us: what if x is object? 1: object x; 2:  3: x = 3.14; 4:  5: int truncated = (int) x; On the surface, this seems fine.  We have a double and we place it into an object which can be done implicitly through boxing (no cast) because all types inherit from object.  Then we cast it to int.  This theoretically should be possible because we know we can explicitly convert a double to an int through a conversion process which involves truncation. But here’s the pitfall: when casting an object to another type, we are casting a reference type, not a value type!  This means that it will attempt to see at runtime if the value boxed and referred to by x is of type int or derived from type int.  Since it obviously isn’t (it’s a double after all) we get an invalid cast exception! Now, you may say this looks awfully contrived, but in truth we can run into this a lot if we’re not careful.  Consider using an IDataReader to read from a database, and then attempting to select a result row of a particular column type: 1: using (var connection = new SqlConnection("some connection string")) 2: using (var command = new SqlCommand("select * from employee", connection)) 3: using (var reader = command.ExecuteReader()) 4: { 5: while (reader.Read()) 6: { 7: // if the salary is not an int32 in the SQL database, this is an error! 8: // doesn't matter if short, long, double, float, reader [] returns object! 9: total += (int) reader["annual_salary"]; 10: } 11: } Notice that since the reader indexer returns object, if we attempt to convert using a cast to a type, we have to make darn sure we use the true, actual type or this will fail!  If the SQL database column is a double, float, short, etc this will fail at runtime with an invalid cast exception because it attempts to convert the object reference! So, how do you get around this?  There are two ways, you could first cast the object to its actual type (double), and then do a narrowing cast to on the value to int.  Or you could use a helper class like Convert which analyzes the actual run-time type and will perform a conversion as long as the type implements IConvertible. 1: object x; 2:  3: x = 3.14; 4:  5: // if you want to cast, must cast out of object to double, then 6: // cast convert. 7: int truncated = (int)(double) x; 8:  9: // or you can call a helper class like Convert which examines runtime 10: // type of the value being converted 11: int anotherTruncated = Convert.ToInt32(x); Summary You should always be careful when performing a conversion cast from values boxed in object that you are actually casting to the true type (or a sub-type). Since casting from object is a widening of the reference, be careful that you either know the exact, explicit type you expect to be held in the object, or instead avoid the cast and use a helper class to perform a safe conversion to the type you desire. Technorati Tags: C#,.NET,Pitfalls,Little Pitfalls,BlackRabbitCoder

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• Silverlight Cream for November 21, 2011 -- #1171

  - by Dave Campbell

  In this Issue: Colin Eberhardt, Sumit Dutta, Morten Nielsen, Jesse Liberty, Jeff Blankenburg(-2-), Brian Noyes, and Tony Champion. Above the Fold: Silverlight: "PV Basics : Client-side Collections" Tony Champion WP7: "Pushpin Clustering with the Windows Phone 7 Bing Map control" Colin Eberhardt Shoutouts: Michael Palermo's latest Desert Mountain Developers is up Michael Washington's latest Visual Studio #LightSwitch Daily is up From SilverlightCream.com: Pushpin Clustering with the Windows Phone 7 Bing Map control Colin Eberhardt is back discussing Pushpins for a BingMaps app on WP7 and provides a utility class that clusters pushpins, allowing you to render 1000s of pins on an app ... all the explanation and all the code Part 22 - Windows Phone 7 - Tile Push Notification Part 22 in Sumit Dutta's WP7 series is about Tile Push Notification... nice tutorial with all the code listed Correctly displaying your current location Morten Nielsen demonstrates formatting the information from the GPS on your WP7 into something intelligible and useful Spiking the Pomodoro Timer Jesse Liberty put up a quick and dirty version of a Pomodoro timer for WP7.1 to explore the technical challenges of the Full Stack Phase 2 he's cranking up 31 Days of Mango | Day #11: Network Jeff Blankenburg's Number 10 in his 31 Days quest of WP7.1 is about the NetworkInformation namespace which gives you all sorts of info on the user's device network connection availability, type, etc. 31 Days of Mango | Day #11: Live Tiles Jeff Blankenburg takes off on Live Tiles for Day 11... big topic for a 1 day post, but he takes off on it... updating and Live Tiles too Working with Prism 4 Part 2: MVVM Basics and Commands Brian Noyes has part 2 of his Prism/MVVM series up at SilverlightShow... very nice tutorial on the basics of getting a view and viewmodel up, and setting up an ICommand to launch an Edit View... plus the code to peruse. PV Basics : Client-side Collections Tony Champion is startig a series on Silverlight 5 and Pivot Viewer... First up is some basics in dealing with the control in SL5 and talking about Client-side Collections... great informative tutorial and all the code Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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• C#/.NET Fundamentals: Choosing the Right Collection Class

  - by James Michael Hare

  The .NET Base Class Library (BCL) has a wide array of collection classes at your disposal which make it easy to manage collections of objects. While it's great to have so many classes available, it can be daunting to choose the right collection to use for any given situation. As hard as it may be, choosing the right collection can be absolutely key to the performance and maintainability of your application! This post will look at breaking down any confusion between each collection and the situations in which they excel. We will be spending most of our time looking at the System.Collections.Generic namespace, which is the recommended set of collections. The Generic Collections: System.Collections.Generic namespace The generic collections were introduced in .NET 2.0 in the System.Collections.Generic namespace. This is the main body of collections you should tend to focus on first, as they will tend to suit 99% of your needs right up front. It is important to note that the generic collections are unsynchronized. This decision was made for performance reasons because depending on how you are using the collections its completely possible that synchronization may not be required or may be needed on a higher level than simple method-level synchronization. Furthermore, concurrent read access (all writes done at beginning and never again) is always safe, but for concurrent mixed access you should either synchronize the collection or use one of the concurrent collections. So let's look at each of the collections in turn and its various pros and cons, at the end we'll summarize with a table to help make it easier to compare and contrast the different collections. The Associative Collection Classes Associative collections store a value in the collection by providing a key that is used to add/remove/lookup the item. Hence, the container associates the value with the key. These collections are most useful when you need to lookup/manipulate a collection using a key value. For example, if you wanted to look up an order in a collection of orders by an order id, you might have an associative collection where they key is the order id and the value is the order. The Dictionary<TKey,TVale> is probably the most used associative container class. The Dictionary<TKey,TValue> is the fastest class for associative lookups/inserts/deletes because it uses a hash table under the covers. Because the keys are hashed, the key type should correctly implement GetHashCode() and Equals() appropriately or you should provide an external IEqualityComparer to the dictionary on construction. The insert/delete/lookup time of items in the dictionary is amortized constant time - O(1) - which means no matter how big the dictionary gets, the time it takes to find something remains relatively constant. This is highly desirable for high-speed lookups. The only downside is that the dictionary, by nature of using a hash table, is unordered, so you cannot easily traverse the items in a Dictionary in order. The SortedDictionary<TKey,TValue> is similar to the Dictionary<TKey,TValue> in usage but very different in implementation. The SortedDictionary<TKey,TValye> uses a binary tree under the covers to maintain the items in order by the key. As a consequence of sorting, the type used for the key must correctly implement IComparable<TKey> so that the keys can be correctly sorted. The sorted dictionary trades a little bit of lookup time for the ability to maintain the items in order, thus insert/delete/lookup times in a sorted dictionary are logarithmic - O(log n). Generally speaking, with logarithmic time, you can double the size of the collection and it only has to perform one extra comparison to find the item. Use the SortedDictionary<TKey,TValue> when you want fast lookups but also want to be able to maintain the collection in order by the key. The SortedList<TKey,TValue> is the other ordered associative container class in the generic containers. Once again SortedList<TKey,TValue>, like SortedDictionary<TKey,TValue>, uses a key to sort key-value pairs. Unlike SortedDictionary, however, items in a SortedList are stored as an ordered array of items. This means that insertions and deletions are linear - O(n) - because deleting or adding an item may involve shifting all items up or down in the list. Lookup time, however is O(log n) because the SortedList can use a binary search to find any item in the list by its key. So why would you ever want to do this? Well, the answer is that if you are going to load the SortedList up-front, the insertions will be slower, but because array indexing is faster than following object links, lookups are marginally faster than a SortedDictionary. Once again I'd use this in situations where you want fast lookups and want to maintain the collection in order by the key, and where insertions and deletions are rare. The Non-Associative Containers The other container classes are non-associative. They don't use keys to manipulate the collection but rely on the object itself being stored or some other means (such as index) to manipulate the collection. The List<T> is a basic contiguous storage container. Some people may call this a vector or dynamic array. Essentially it is an array of items that grow once its current capacity is exceeded. Because the items are stored contiguously as an array, you can access items in the List<T> by index very quickly. However inserting and removing in the beginning or middle of the List<T> are very costly because you must shift all the items up or down as you delete or insert respectively. However, adding and removing at the end of a List<T> is an amortized constant operation - O(1). Typically List<T> is the standard go-to collection when you don't have any other constraints, and typically we favor a List<T> even over arrays unless we are sure the size will remain absolutely fixed. The LinkedList<T> is a basic implementation of a doubly-linked list. This means that you can add or remove items in the middle of a linked list very quickly (because there's no items to move up or down in contiguous memory), but you also lose the ability to index items by position quickly. Most of the time we tend to favor List<T> over LinkedList<T> unless you are doing a lot of adding and removing from the collection, in which case a LinkedList<T> may make more sense. The HashSet<T> is an unordered collection of unique items. This means that the collection cannot have duplicates and no order is maintained. Logically, this is very similar to having a Dictionary<TKey,TValue> where the TKey and TValue both refer to the same object. This collection is very useful for maintaining a collection of items you wish to check membership against. For example, if you receive an order for a given vendor code, you may want to check to make sure the vendor code belongs to the set of vendor codes you handle. In these cases a HashSet<T> is useful for super-quick lookups where order is not important. Once again, like in Dictionary, the type T should have a valid implementation of GetHashCode() and Equals(), or you should provide an appropriate IEqualityComparer<T> to the HashSet<T> on construction. The SortedSet<T> is to HashSet<T> what the SortedDictionary<TKey,TValue> is to Dictionary<TKey,TValue>. That is, the SortedSet<T> is a binary tree where the key and value are the same object. This once again means that adding/removing/lookups are logarithmic - O(log n) - but you gain the ability to iterate over the items in order. For this collection to be effective, type T must implement IComparable<T> or you need to supply an external IComparer<T>. Finally, the Stack<T> and Queue<T> are two very specific collections that allow you to handle a sequential collection of objects in very specific ways. The Stack<T> is a last-in-first-out (LIFO) container where items are added and removed from the top of the stack. Typically this is useful in situations where you want to stack actions and then be able to undo those actions in reverse order as needed. The Queue<T> on the other hand is a first-in-first-out container which adds items at the end of the queue and removes items from the front. This is useful for situations where you need to process items in the order in which they came, such as a print spooler or waiting lines. So that's the basic collections. Let's summarize what we've learned in a quick reference table.  Collection Ordered? Contiguous Storage? Direct Access? Lookup Efficiency Manipulate Efficiency Notes Dictionary No Yes Via Key Key: O(1) O(1) Best for high performance lookups. SortedDictionary Yes No Via Key Key: O(log n) O(log n) Compromise of Dictionary speed and ordering, uses binary search tree. SortedList Yes Yes Via Key Key: O(log n) O(n) Very similar to SortedDictionary, except tree is implemented in an array, so has faster lookup on preloaded data, but slower loads. List No Yes Via Index Index: O(1) Value: O(n) O(n) Best for smaller lists where direct access required and no ordering. LinkedList No No No Value: O(n) O(1) Best for lists where inserting/deleting in middle is common and no direct access required. HashSet No Yes Via Key Key: O(1) O(1) Unique unordered collection, like a Dictionary except key and value are same object. SortedSet Yes No Via Key Key: O(log n) O(log n) Unique ordered collection, like SortedDictionary except key and value are same object. Stack No Yes Only Top Top: O(1) O(1)* Essentially same as List<T> except only process as LIFO Queue No Yes Only Front Front: O(1) O(1) Essentially same as List<T> except only process as FIFO   The Original Collections: System.Collections namespace The original collection classes are largely considered deprecated by developers and by Microsoft itself. In fact they indicate that for the most part you should always favor the generic or concurrent collections, and only use the original collections when you are dealing with legacy .NET code. Because these collections are out of vogue, let's just briefly mention the original collection and their generic equivalents: ArrayList A dynamic, contiguous collection of objects. Favor the generic collection List<T> instead. Hashtable Associative, unordered collection of key-value pairs of objects. Favor the generic collection Dictionary<TKey,TValue> instead. Queue First-in-first-out (FIFO) collection of objects. Favor the generic collection Queue<T> instead. SortedList Associative, ordered collection of key-value pairs of objects. Favor the generic collection SortedList<T> instead. Stack Last-in-first-out (LIFO) collection of objects. Favor the generic collection Stack<T> instead. In general, the older collections are non-type-safe and in some cases less performant than their generic counterparts. Once again, the only reason you should fall back on these older collections is for backward compatibility with legacy code and libraries only. The Concurrent Collections: System.Collections.Concurrent namespace The concurrent collections are new as of .NET 4.0 and are included in the System.Collections.Concurrent namespace. These collections are optimized for use in situations where multi-threaded read and write access of a collection is desired. The concurrent queue, stack, and dictionary work much as you'd expect. The bag and blocking collection are more unique. Below is the summary of each with a link to a blog post I did on each of them. ConcurrentQueue Thread-safe version of a queue (FIFO). For more information see: C#/.NET Little Wonders: The ConcurrentStack and ConcurrentQueue ConcurrentStack Thread-safe version of a stack (LIFO). For more information see: C#/.NET Little Wonders: The ConcurrentStack and ConcurrentQueue ConcurrentBag Thread-safe unordered collection of objects. Optimized for situations where a thread may be bother reader and writer. For more information see: C#/.NET Little Wonders: The ConcurrentBag and BlockingCollection ConcurrentDictionary Thread-safe version of a dictionary. Optimized for multiple readers (allows multiple readers under same lock). For more information see C#/.NET Little Wonders: The ConcurrentDictionary BlockingCollection Wrapper collection that implement producers & consumers paradigm. Readers can block until items are available to read. Writers can block until space is available to write (if bounded). For more information see C#/.NET Little Wonders: The ConcurrentBag and BlockingCollection Summary The .NET BCL has lots of collections built in to help you store and manipulate collections of data. Understanding how these collections work and knowing in which situations each container is best is one of the key skills necessary to build more performant code. Choosing the wrong collection for the job can make your code much slower or even harder to maintain if you choose one that doesn’t perform as well or otherwise doesn’t exactly fit the situation. Remember to avoid the original collections and stick with the generic collections.  If you need concurrent access, you can use the generic collections if the data is read-only, or consider the concurrent collections for mixed-access if you are running on .NET 4.0 or higher.   Tweet Technorati Tags: C#,.NET,Collecitons,Generic,Concurrent,Dictionary,List,Stack,Queue,SortedList,SortedDictionary,HashSet,SortedSet

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• Do NOT Change "Copy Local” project references to false, unless understand subsequences.

  - by Michael Freidgeim

  To optimize performance of visual studio build I've found multiple recommendations to change CopyLocal property for dependent dlls to false,e.g. From http://stackoverflow.com/questions/690033/best-practices-for-large-solutions-in-visual-studio-2008 CopyLocal? For sure turn this offhttp://stackoverflow.com/questions/280751/what-is-the-best-practice-for-copy-local-and-with-project-referencesAlways set the Copy Local property to false and enforce this via a custom msbuild stephttp://codebetter.com/patricksmacchia/2007/06/20/benefit-from-the-c-and-vb-net-compilers-perf/BenefitBenefitMy advice is to always set ‘Copy Local’ to falseSome time ago we've tried to change the setting to false, and found that it causes problem for deployment of top-level projects.Recently I've followed the suggestion and changed the settings for middle-level projects. It didn't cause immediate issues, but I was warned by Readify Consultant Colin Savage about possible errors during deploymentsI haven't undone the changes immediately and we found a few issues during testing.There are many scenarios, when you need to have Copy Local’ left to True.The concerns are highlighted in some stack overflow answers, but they have small number of votes.Top-level projects:  set copy local = true.First of all, it doesn't work correctly for top-level projects, i.e. executables or web sites.As pointed in the answer http://stackoverflow.com/a/6529461/52277for all the references in the one at the top set copy local = true.Alternatively you have to change output directory as it's described in http://www.simple-talk.com/dotnet/.net-framework/partitioning-your-code-base-through-.net-assemblies-and-visual-studio-projects/If you set ‘ Copy Local = false’, VS will, unless you tell it otherwise, place each assembly alone in its own .\bin\Debugdirectory. Because of this, you will need to configure VS to place assemblies together in the same directory. To do so, for each VS project, go to VS > Project Properties > Build tab > Output path, and set the Ouput path to ..\bin\Debugfor debug configuration, and ..\bin\Release for release configuration.Second-level  dependencies:  set copy local = true.Another example when copylocal =false fails on run-time, is when top level assembly doesn't directly referenced one of indirect dependencies.E..g. Top-level assembly A has reference to assembly B with copylocal =true, but assembly B has reference to assembly C with copylocal =false. Most likely assembly C will be missing on runtime and will cause errors E.g. http://stackoverflow.com/questions/602765/when-should-copy-local-be-set-to-true-and-when-should-it-not?lq=1Copy local is important for deployment scenarios and tools. As a general rule you should use CopyLocal=True and http://stackoverflow.com/questions/602765/when-should-copy-local-be-set-to-true-and-when-should-it-not?lq=1 Unfortunately there are some quirks and CopyLocal won't necessary work as expected for assembly references in secondary assemblies structured as shown below.MainApp.exe MyLibrary.dll ThirdPartyLibrary.dll (if in the GAC CopyLocal won't copy to MainApp bin folder)This makes xcopy deployments difficult . .Reflection called DLLs  dependencies:  set copy local = true.E.g user can see error "ISystem.Reflection.ReflectionTypeLoadException: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information."The fix for the issue is recommended in http://stackoverflow.com/a/6200173/52277"I solved this issue by setting the Copy Local attribute of my project's references to true."In general, the problems with investigation of deployment issues may overweight the benefits of reduced build time. Setting the Copy Local to false without considering deployment issues is not a good idea.

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• I want to hit Apex SQL with a big stick

  - by Michael Stephenson

  <Whinge> Thought id just have a little whinge about this product which caused me a load of grief the other day..... So the background was that my development machine had a completely full hard disk which I needed to sort out.  Upon investigation I found the issue was that the msdb database had managed to get very large. This was caused because a long time ago (and I cant even remember why) I tried out Apex SQL.  After a few days I decided to uninstall it and thought nothing more of it.  What I didnt realise was that uninstalling it doesnt actually uninstall it (and it doesnt inform you about this), but there was still some assemblies left on my machine.  Everytime SQL Server was running it was starting the Apex SQL Connection monitor which was then running in the background and regularly recording information in the msdb database.  Over time it had recorded enough to fill the disk. The below article advises how to sort this out by removing this fully so if your having a problem then try this out:http://knowledgebase.apexsql.com/2007/08/how-to-uninstall-apexsqlconnectionmonit_09.htm Once this was sorted out its interesting to read the above article because I just dont think the approach used by the vendor of this software is a very good one.  So for the Apex team just wanted to pass on a thought: If I want to uninstall your product you should tell me if stuff is left on the machine especially if a process will be running which is going to fill my machine with useless data, </Whinge>

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• How to run 'apt-get install' to install all dependencies?

  - by michael

  I am running this in ubuntu server installation: sudo apt-get install git-core gnupg flex bison gperf build-essential \ zip curl libc6-dev libncurses5-dev:i386 x11proto-core-dev \ libx11-dev:i386 libreadline6-dev:i386 libgl1-mesa-glx:i386 \ libgl1-mesa-dev g++-multilib mingw32 openjdk-6-jdk tofrodos \ python-markdown libxml2-utils xsltproc zlib1g-dev:i386 but I am getting this: Reading package lists... Building dependency tree... Reading state information... curl is already the newest version. gnupg is already the newest version. Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: build-essential : Depends: gcc (>= 4:4.4.3) but it is not going to be installed Depends: g++ (>= 4:4.4.3) but it is not going to be installed g++-multilib : Depends: cpp (>= 4:4.7.2-1ubuntu2) but it is not going to be installed Depends: gcc-multilib (>= 4:4.7.2-1ubuntu2) but it is not going to be installed Depends: g++ (>= 4:4.7.2-1ubuntu2) but it is not going to be installed Depends: g++-4.7-multilib (>= 4.7.2-1~) but it is not going to be installed How can I fix this?

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