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  • GRUB doesn't recognize partitions on one harddisk

    - by knizz
    I have a dualboot computer with Windows Vista (on hd0) and Ubuntu 9.10. The bootloader is GRUB and the windows bootloader lets me decide between Vista and Ubuntu-Installation (broken WuBi). But now (i don't know why that changed) I can't use start the windows-bootloader anymore. I tried "ls" on the grub-prompt and it gave me a list like: (hd0) (hd1) (hd1,0) (hd1,1) (hd1,2) ... (fd0) It recognizes all partitions of hd1 (the ubuntu-harddisk) but not of hd0(the win-disk). .. WHY? Here is the result of the "boot info script" for the technical details: Boot Info Script 0.55 dated February 15th, 2010 ============================= Boot Info Summary: ============================== => Grub 2 is installed in the MBR of /dev/sda and looks for (UUID=a7c510e3-2399-437b-ab92-fa609e48d63f)/boot/grub. => No boot loader is installed in the MBR of /dev/sdb sda1: _________________________________________________________________________ File system: ntfs Boot sector type: Windows Vista/7 Boot sector info: No errors found in the Boot Parameter Block. Operating System: Windows Vista Boot files/dirs: /bootmgr /Boot/BCD /Windows/System32/winload.exe /wubildr.mbr /wubildr sda2: _________________________________________________________________________ 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: sdb1: _________________________________________________________________________ File system: Boot sector type: Unknown Boot sector info: Mounting failed: mount: unbekannter Dateisystemtyp „“ 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: Bios Boot Partition Boot sector type: - Boot sector info: sdb4: _________________________________________________________________________ File system: ext4 Boot sector type: - Boot sector info: Operating System: Ubuntu 9.10 Boot files/dirs: /boot/grub/grub.cfg /etc/fstab /boot/grub/core.img sdb5: _________________________________________________________________________ File system: swap Boot sector type: - Boot sector info: =========================== Drive/Partition Info: ============================= Drive: sda ___________________ _____________________________________________________ Platte /dev/sda: 640.1 GByte, 640135028736 Byte 255 Köpfe, 63 Sektoren/Spuren, 77825 Zylinder, zusammen 1250263728 Sektoren Einheiten = Sektoren von 1 × 512 = 512 Bytes Disk identifier: 0x52554d66 Partition Boot Start End Size Id System /dev/sda1 * 2,048 307,202,047 307,200,000 7 HPFS/NTFS /dev/sda2 307,202,048 1,250,258,943 943,056,896 7 HPFS/NTFS Drive: sdb ___________________ _____________________________________________________ Platte /dev/sdb: 640.1 GByte, 640135028736 Byte 255 Köpfe, 63 Sektoren/Spuren, 77825 Zylinder, zusammen 1250263728 Sektoren Einheiten = Sektoren von 1 × 512 = 512 Bytes Disk identifier: 0x00000000 Partition Boot Start End Size Id System /dev/sdb1 1 1,250,263,727 1,250,263,727 ee GPT GUID Partition Table detected. Partition Start End Size System /dev/sdb1 34 262,177 262,144 Microsoft Windows /dev/sdb2 262,178 1,131,253,933 1,130,991,756 Linux or Data /dev/sdb3 1,131,253,934 1,131,255,887 1,954 Bios Boot Partition /dev/sdb4 1,131,255,888 1,245,312,528 114,056,641 Linux or Data /dev/sdb5 1,245,312,529 1,250,263,694 4,951,166 Linux Swap blkid -c /dev/null: ____________________________________________________________ Device UUID TYPE LABEL /dev/sda1 AE1440441440122F ntfs /dev/sda2 3AE66E4DE66E0A09 ntfs data /dev/sdb2 5419D16119DAA4DE ntfs LaufwerkD /dev/sdb4 a7c510e3-2399-437b-ab92-fa609e48d63f ext4 /dev/sdb5 60a0143a-e01b-450a-bbd1-f22059e47b65 swap ============================ "mount | grep ^/dev output: =========================== Device Mount_Point Type Options /dev/sdb4 / ext4 (rw,errors=remount-ro) =========================== sdb4/boot/grub/grub.cfg: =========================== # # DO NOT EDIT THIS FILE # # It is automatically generated by /usr/sbin/grub-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub # ### BEGIN /etc/grub.d/00_header ### if [ -s /boot/grub/grubenv ]; then have_grubenv=true load_env fi set default="0" if [ ${prev_saved_entry} ]; then saved_entry=${prev_saved_entry} save_env saved_entry prev_saved_entry= save_env prev_saved_entry fi insmod ext2 set root=(hd1,4) search --no-floppy --fs-uuid --set a7c510e3-2399-437b-ab92-fa609e48d63f if loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=640x480 insmod gfxterm insmod vbe if terminal_output gfxterm ; then true ; else # For backward compatibility with versions of terminal.mod that don't # understand terminal_output terminal gfxterm fi fi 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/white ### END /etc/grub.d/05_debian_theme ### ### BEGIN /etc/grub.d/10_linux ### menuentry "Ubuntu, Linux 2.6.31-20-generic" { recordfail=1 if [ -n ${have_grubenv} ]; then save_env recordfail; fi set quiet=1 insmod ext2 set root=(hd1,4) search --no-floppy --fs-uuid --set a7c510e3-2399-437b-ab92-fa609e48d63f linux /boot/vmlinuz-2.6.31-20-generic root=UUID=a7c510e3-2399-437b-ab92-fa609e48d63f ro quiet splash initrd /boot/initrd.img-2.6.31-20-generic } menuentry "Ubuntu, Linux 2.6.31-20-generic (recovery mode)" { recordfail=1 if [ -n ${have_grubenv} ]; then save_env recordfail; fi insmod ext2 set root=(hd1,4) search --no-floppy --fs-uuid --set a7c510e3-2399-437b-ab92-fa609e48d63f linux /boot/vmlinuz-2.6.31-20-generic root=UUID=a7c510e3-2399-437b-ab92-fa609e48d63f ro single initrd /boot/initrd.img-2.6.31-20-generic } menuentry "Ubuntu, Linux 2.6.31-14-generic" { recordfail=1 if [ -n ${have_grubenv} ]; then save_env recordfail; fi set quiet=1 insmod ext2 set root=(hd1,4) search --no-floppy --fs-uuid --set a7c510e3-2399-437b-ab92-fa609e48d63f linux /boot/vmlinuz-2.6.31-14-generic root=UUID=a7c510e3-2399-437b-ab92-fa609e48d63f ro quiet splash initrd /boot/initrd.img-2.6.31-14-generic } menuentry "Ubuntu, Linux 2.6.31-14-generic (recovery mode)" { recordfail=1 if [ -n ${have_grubenv} ]; then save_env recordfail; fi insmod ext2 set root=(hd1,4) search --no-floppy --fs-uuid --set a7c510e3-2399-437b-ab92-fa609e48d63f linux /boot/vmlinuz-2.6.31-14-generic root=UUID=a7c510e3-2399-437b-ab92-fa609e48d63f ro single initrd /boot/initrd.img-2.6.31-14-generic } ### END /etc/grub.d/10_linux ### ### BEGIN /etc/grub.d/20_memtest86+ ### menuentry "Memory test (memtest86+)" { linux16 /boot/memtest86+.bin } menuentry "Memory test (memtest86+, serial console 115200)" { linux16 /boot/memtest86+.bin console=ttyS0,115200n8 } ### END /etc/grub.d/20_memtest86+ ### ### BEGIN /etc/grub.d/30_os-prober ### menuentry "Windows Vista (loader) (on /dev/sda1)" { insmod ntfs set root=(hd0,1) search --no-floppy --fs-uuid --set ae1440441440122f 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 ### =============================== sdb4/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 defaults 0 0 # / was on /dev/sdb4 during installation UUID=a7c510e3-2399-437b-ab92-fa609e48d63f / ext4 errors=remount-ro 0 1 # swap was on /dev/sdb5 during installation UUID=60a0143a-e01b-450a-bbd1-f22059e47b65 none swap sw 0 0 /dev/scd0 /media/cdrom0 udf,iso9660 user,noauto,exec,utf8 0 0 /dev/fd0 /media/floppy0 auto rw,user,noauto,exec,utf8 0 0 =================== sdb4: Location of files loaded by Grub: =================== 583.8GB: boot/grub/core.img 583.8GB: boot/grub/grub.cfg 579.7GB: boot/initrd.img-2.6.31-14-generic 580.0GB: boot/initrd.img-2.6.31-20-generic 579.7GB: boot/vmlinuz-2.6.31-14-generic 579.8GB: boot/vmlinuz-2.6.31-20-generic 580.0GB: initrd.img 579.7GB: initrd.img.old 579.8GB: vmlinuz 579.7GB: vmlinuz.old =========================== Unknown MBRs/Boot Sectors/etc ======================= Unknown BootLoader on sdb1 00000000 54 34 dc 3b 8b ff 6c fa 3e 59 3d 24 25 af 5f 9b |T4.;..l.>Y=$%._.| 00000010 72 f8 36 3d 56 30 22 fd c6 08 5e 39 7f dc 29 48 |r.6=V0"...^9..)H| 00000020 48 e5 24 52 77 b0 fc 64 b6 ce 48 c3 07 ce b5 81 |H.$Rw..d..H.....| 00000030 06 68 60 4f 6e fb 83 92 df 3a 54 b9 df 21 2a cd |.h`On....:T..!*.| 00000040 1e 2f e2 49 fe cf 81 2d 52 17 1a 4e 66 b4 f3 f0 |./.I...-R..Nf...| 00000050 41 25 e3 96 26 28 fe 19 61 72 75 f8 40 a3 b7 ef |A%..&(..aru.@...| 00000060 5f 79 dc cb 28 44 44 7c 9b 9a 7b 6c 4b 4b 60 0f |_y..(DD|..{lKK`.| 00000070 a9 97 87 bc 85 9f db bb d2 1a 88 9f aa 49 18 d5 |.............I..| 00000080 92 2d db 7e fe f7 8d 7a 18 c0 33 c5 bd 7a 46 07 |.-.~...z..3..zF.| 00000090 c8 27 13 66 94 49 62 9f bc 99 56 55 25 fb 94 a9 |.'.f.Ib...VU%...| 000000a0 3f b2 a7 0a 87 d0 a4 4e 51 f1 09 02 c4 29 eb ff |?......NQ....)..| 000000b0 26 3b 51 3e 5a 0c db ee a6 57 a7 c3 ba a1 74 90 |&;Q>Z....W....t.| 000000c0 ee 70 08 18 cc b8 d0 22 ce 96 c7 cb 68 40 98 20 |.p....."....h@. | 000000d0 49 3d 07 ec df d1 8d cf 19 bc 42 90 70 24 01 b4 |I=........B.p$..| 000000e0 28 cf c6 50 d3 95 5a 1b 18 15 33 c7 b2 a8 95 92 |(..P..Z...3.....| 000000f0 bb 93 fe 18 2b 81 c1 6b 9c 30 f1 65 50 6a 80 3d |....+..k.0.ePj.=| 00000100 74 37 a8 59 a6 51 8a 63 b6 d8 16 9f a9 47 2a 7c |t7.Y.Q.c.....G*|| 00000110 04 a7 fe 69 47 02 bf e9 b7 1b 7a ea 60 5c 3c 53 |...iG.....z.`\<S| 00000120 5b 10 78 dc 4d d2 a8 22 30 45 37 fb 56 06 9f 06 |[.x.M.."0E7.V...| 00000130 aa df cf 87 3a 3e cf 72 f2 e5 a6 c6 aa e2 7c 1c |....:>.r......|.| 00000140 64 c2 fc 80 ce 02 fc 7f 0f c6 60 81 bf cd 3b 5a |d.........`...;Z| 00000150 37 a5 38 1b 0c 1b 39 2e d6 f6 3d a2 36 e5 87 c3 |7.8...9...=.6...| 00000160 17 b5 fd ee 33 c7 ce a3 d9 c2 57 dc ee 85 48 9d |....3.....W...H.| 00000170 33 60 02 cd c5 83 44 44 ea b6 07 25 0a 4b a6 6e |3`....DD...%.K.n| 00000180 fc 51 42 cd 84 0b 65 b6 19 a1 e5 b2 eb 14 0c fa |.QB...e.........| 00000190 24 77 f5 44 6e 5d 39 dd b6 8e cc f8 30 fe 21 46 |$w.Dn]9.....0.!F| 000001a0 9c ff 95 c6 c7 b5 0a df 54 ca d2 ac bc 64 d0 97 |........T....d..| 000001b0 94 54 d9 29 0f 91 60 20 c3 e4 53 c2 b0 e4 40 72 |.T.)..` ..S...@r| 000001c0 7e 25 bc 81 06 ad 05 46 14 a7 e6 71 6b 5c db 9c |~%.....F...qk\..| 000001d0 0a 5e 76 23 ae 06 01 36 98 21 65 2c 90 e7 4b 1a |.^v#...6.!e,..K.| 000001e0 2a 2d 80 a5 48 db 9e 14 e0 9f e9 aa 00 e3 77 32 |*-..H.........w2| 000001f0 0f fd 94 db 55 a6 64 46 be ae ca de da ee 89 68 |....U.dF.......h| 00000200 =======Devices which don't seem to have a corresponding hard drive============== sdc sdd sde

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  • Apache/Mongrel/Redmine installation problem (VirtualHost/ProxyPass)

    - by Riddler
    I am installing Redmine as per this step-by-step instruction: http://justnotes.co.cc/2010/02/11/how-to-install-redmine-on-ubuntu/ I am using Ubuntu 10.04.1, Apache 2.2.14, Mongrel 1.1.5. On the VirtualHost configuration stage, I am using this: <VirtualHost *:80> ServerName myserver.lv ProxyPass /redmine/ http://localhost:8000/ ProxyPassReverse /redmine/ http://localhost:8000 ProxyPreserveHost on <Proxy *> Order allow,deny Allow from all </Proxy> </VirtualHost> But, when I direct my browser to http://<my-server's-ip>/redmine/ what I see is not the redmine web application but "Index of /redmine" with, well, index of the files from the root directory of Redmine. Any idea how to fix that? P.S. Tried removing the VirtualHost stuff alltogether and instead adding the following simple clauses to apache2.conf: <Proxy *> Order allow,deny Allow from all </Proxy> ProxyPass /redmine/ http://localhost:8000/ ProxyPassReverse /redmine/ http://localhost:8000/ ProxyPreserveHost on As a result, the behavior changes! Now http://<my-server's-ip>/redmine/ produces the source code of the Redmine's start page, so it is served, but apparently not rendered. At the same time, still, http://<my-server's-ip>:8000/ works perfectly fine, so Mongrel is serving the Redmine application as it should, it's just that something is wrong with my VirtualHost/proxying clauses in the .conf file.

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  • pure-ftpd not listening on specified port

    - by Jason McLaren
    I installed the pure-ftpd package (version 1.0.35-1) on an Ubuntu 12.04 box (an EC2 instance based on the standard Ubuntu 12.04 AMI). The pure-ftpd daemon is running (verified with ps), though there is no PID file (expected one to be created by the /etc/init.d/pure-ftpd script). Here's the resulting command that gets run by the init.d script: /usr/sbin/pure-ftpd -l pam -O clf:/var/log/pure-ftpd/transfer.log -o -8 UTF-8 -u 1000 -E -B -g /var/run/pure-ftpd/pure-ftpd.pid Here's my real problem: the ftp server isn't actually listening on any port (checked with netstat and nmap). So I can't ftp to the server (either locally using localhost or remotely using the public IP address). I tried adding a Bind file to /etc/pure-ftpd/conf and restarting, but it didn't help. When I installed pure-ftpd, it replaced inetd with openbsd-inetd, but did not run it since there were no services enabled. So inetd is not listening on port 21 either. (Apparently Ubuntu has a no-inetd-by-default policy, according to https://lists.ubuntu.com/archives/ubuntu-users/2010-September/227905.html .) I want to run pure-ftpd by itself (not with inetd) anyways, since the /etc/init.d/pure-ftpd script requires no inetd if you use the UploadScript feature. I'm not familiar with how Ubuntu handles network services (and can't find any relevant docs besides generic man pages), so I'm probably missing something obvious. Nothing seems out of the ordinary with /etc/hosts.allow (empty) or hosts.deny (empty), and I didn't add any firewall rules (iptables -L shows that the firewall is in its initial state). I've checked the pure-ftpd docs; not sure what else to look at. Any help would be appreciated, thanks!

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  • trying to allow domain admins access in apache

    - by sharif
    I am trying to authenticate domain admins through apache and it is not working. Error i get is as follows [Mon Sep 24 14:54:45 2012] [debug] src/mod_auth_kerb.c(1432): [client 172.16.0.85] kerb_authenticate_user entered with user (NULL) and auth_type Kerberos [Mon Sep 24 14:54:45 2012] [debug] src/mod_auth_kerb.c(915): [client 172.16.0.85] Using HTTP/[email protected] as server principal for password verification [Mon Sep 24 14:54:45 2012] [debug] src/mod_auth_kerb.c(655): [client 172.16.0.85] Trying to get TGT for user [email protected] [Mon Sep 24 14:54:45 2012] [debug] src/mod_auth_kerb.c(569): [client 172.16.0.85] Trying to verify authenticity of KDC using principal HTTP/[email protected] [Mon Sep 24 14:54:45 2012] [debug] src/mod_auth_kerb.c(994): [client 172.16.0.85] kerb_authenticate_user_krb5pwd ret=0 [email protected] authtype=Basic [Mon Sep 24 14:54:45 2012] [debug] mod_authnz_ldap.c(561): [client 172.16.0.85] ldap authorize: Creating LDAP req structure [Mon Sep 24 14:54:45 2012] [debug] mod_authnz_ldap.c(573): [client 172.16.0.85] auth_ldap authorise: User DN not found, LDAP: ldap_simple_bind_s() failed Below is what I have in my httpd file Alias /compass "/data/intranet/html/compass" <Directory "/data/intranet/html/compass"> AuthType Kerberos AuthName KerberosLogin KrbServiceName HTTP/intranet.xxx.com KrbMethodNegotiate On KrbMethodK5Passwd On KrbAuthRealms xxx.COM Krb5KeyTab /etc/httpd/conf/intranet.keytab # require valid-user # Options Indexes MultiViews FollowSymLinks # AllowOverride All # Order allow,deny # Allow from all # SetOutputFilter DEFLATE # taken from http://blogs.freebsdish.org/tmclaugh/2010/07/15/mod_auth_kerb-ad-and-ldap-authorization/ # download extra module and install # Strip the kerberos realm from the principle. # MapUsernameRule (.*)@(.*) "$1" AuthLDAPURL "ldap://echo.uk.xxx.com akhutan.usa.xxx.com/dc=xxx,dc=com?sAMAccountName" AuthLDAPBindDN cn=Administrator,ou=Users,dc=xxx,dc=com AuthLDAPBindPassword *** Require ldap-group cn=Domain Admins,ou=Users,dc=xxx,dc=com </Directory> I have followed this guide. I have download and install the tarball. when I try to uncomment MapUsernameRule i get failed error when restarting apache Reloading httpd: not reloading due to configuration syntax error I am using centos 5 64bit. I have added the following line but i still get syntax error LoadModule mod_map_user modules/mod_map_user.so

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  • PC powers off at random times

    - by Timo Huovinen
    Short Version After experiencing some problems with Mobo batteries my PC started to power off at random times, the power off is instant and sudden and does not restart afterwards, need help figuring out the cause. Facts: Powers off when PC is playing games Powers off when PC is idle Powers off when PC is in safe mode Powers off when PC is in BIOS Powers off when PC is booted through a Windows installation USB Replaced the motherboard battery several times Replaced the 650W PSU with a 750W PSU Replaced the RAM Swapped the RAM between slots Re-applied thermal paste to the CPU Checked if the motherboard touches the case Nothing is overclocked PC Specs PC specs: OS: Windows 7 Ultimate SP1 RAM: klingston 1333MHz 4GB stick CPU: AMD Phenom II x4 955 Mobo: Gigabyte 88GMA-UD2H rev 2.2 Motherboard battery: CR2032 3v HDD: 500GB Seagate ST3500418AS ATA Device Graphics: ATI/AMD Radeon HD 6870 Very Long version Around 10 months ago I built a brand new gaming PC. Around 6 months ago it's time setting in windows started resetting to the year 2010. I swapped the Motherboard battery for a new one of the exact same size and shape and voltage, and the problems disappeared...for around 2 weeks. Then the same problem happened again, time gets reset, I swapped the battery again, and the problem was gone for good and everything was great for about 3 months.. then another problem started happening, the PC started to power off suddenly and without warning at completely random times, sometimes the PC works for and hour, sometimes 5 minutes. So I read on the forums that it might be either the PSU or the motherboard Battery or RAM or HDD or the Graphics card or the CPU or the motherboard or the drivers or a Virus or Grounding issues, or something short circuiting, basically it can be anything... I spent some days researching, and decided to remove the possibility of a virus. I reset the CMOS, cleared all BIOS settings and reinstalled windows 7 after a full format of the HDD, but the random power off kept happening. I then disabled the restart on error option in windows and looked at the event log for error events, but they did not help me figure out the problem. Network list service depends on network location awareness the dependency group failed to start Source Kernel Power Event 41 Task Category 63 Source Disk Event ID 11 Task Category None The driver detected a controller error on device disk I took apart the PC, every little piece, re-applied some expensive thermal paste to the CPU, and double checked that none of the pieces are touching the PC case. The problem was gone, the PC no longer powered off randomly I re-attached the graphics card and all was good for 4 months... then the power off problem appeared again, but was happening at high intervals, the PC would shutdown once in 2 days on average, at random points in time, sometimes when it's idle all day long, sometimes when it's running CRYSIS 2. I checked the CPU temperature, because I know that AMD CPU's have a built in protection mechanism that switches off the PC if the CPU gets too hot, and the Temp was 50C system temp, and 45C CPU after running the PC all day long (I did not do tests to see if there are any temperature spikes, don't know how to do them) Originally the PSU that powered the PC was 650Watts and had one 4 pin cable to power the CPU, I replaced it with a new 750Watts PSU which has two 4 pin cables for the CPU, but the problem remained. I removed the graphics card and let the motherboard use the built in one, but the PC kept suddenly powering off at random times. I took apart the PC completely again, and re-applied thermal paste to the CPU, added lots of insulation, and checked for any type of short-circuit possibility again and again, but the problem remained. The problem was like that for some months. I replaced the Battery a couple of times over the time, changed lots of options in windows, and tried everything I could, but it kept powering off, so I stopped using the PC as much as I used to, just living with the random power offs from time to time, until a couple of days ago, when the power off happens almost immediately after powering on the PC. I replaced the RAM with a brand new one, but that did not help. Took apart the PC again, checked for anything anywhere that might cause it, found some small scratches on the very edge of the motherboard to the left of the PCI express x16 slot. This might cause the problem, I thought, but the scratch looks very superficial, not deep at all, and if the scratch did harm the motherboard, wouldn't it cause it to not start at all? And why did it start to power off a while ago, and then suddenly stop powering off? The scratches could not have vanished??? did chkdsk \d but it powered off when it was at 75% I removed the hard disks, the graphics card, while I fiddled with the BIOS settings, and suddenly the PC shut down while I was looking at the BIOS version. This makes me realize, it is not caused by: HDD, Windows, Drivers or the Graphics card I cleared the CMOS again, updated the BIOS from F5 to F6f beta, but that did not help, it might even seem that the PC powers off even sooner. The shutdown even happened to me while I booted through a windows 7 installation USB and was in the repair console. I removed one of the cables powering the CPU, now only one 4pin cable powers it, and it worked for 30mins after doing that, which makes me think that it's the CPU overheating, and because it gets less power, it overheats slower? The things that I am still considering: CPU overheating (does not seem to overheat, maybe false readings?) Motherboard short circuiting (faulty motherboard?) I desperately need some advice in what is faulty, is it a faulty Motherboard or an overheating CPU? or maybe something else? I have been breaking my head over this problem over a span of 6 months. I'm not sure if this is a good place to ask this question, if it is not, then tell me where I can get some experienced help. More info I have also discovered a mysterious piece that seems to have fallen out of the motherboard i119.photobucket.com/albums/o126/yurikolovsky/strangepiece.jpg What is it? Looks like each time that it powers off the datetime gets reset I also found another forum post tomshardware.co.uk/forum/… except I don't have Integrated PeripheralsUSB Keyboard Function option in BIOS :S Comments summary (asked by Random moderator) Q. tell me, if the computer restarts, is it immediately? Does it take a second and then restarts? Do you see (BSOD) or hear (PSU, short circuit) any suspicious when it happens? After reading trough it, it remains the mainboard that is faulty. – JohannesM A. Immediate power off, all the fans stop instantly, all the light turn off instantly, no sound or anything, and it remains off until I turn it back on. Thanks for the feedback, faulty motherboard is what I fear. Q. Try stress-testing the system with Prime95 and see if errors or shutdowns occur when the CPU is under full load. – speakr A. Prime95 heat stress test peaked CPU heat at 60C after 5mins, it powered off after 30mins of testing in the middle of the test with no errors, Prime95 Heat test or the stress-testing with low RAM usage (small or in-place FFTs) do not report errors while testing for 10-60 mins. The power off does not seem like it is affected by Prime95 at all Makes me wonder if it's a CPU or Motherboard issue at all. Q. I had similar random/intermittent problems with my old board. It gave one of a few different symptoms: keyboard and/or mouse would die and/or the RAM wouldn't work and/or it would shut down. It was in bad shape. One problems was that my old PSU had literally burned the connector on it (browned around the pins), another was that a broken lead inside the layers of the PCB would work sometimes if it happened to be hot or if I bent the board—by jamming a hunk of wood behind it. I managed to keep the board alive for several years, but eventually nothing I did would make it work correctly anymore. – Synetech A. I will try that as the last resort, ok? ;) Q. Have you tried a different power cord, surge protector, outlet (on a different circuit). It's worth a shot just to ensure it's not subpar wiring or a week circuit (dips in power may cause shutdown if the PSU can't pull enough juice from the wall). – Kyle A. yes, I attached the PC to an entirely different outlet on a different circuit and the problem persists. After connecting it to a different outlet after starting the PC it gave me 3 long beeps and 1 short one, then the PC immediately proceeded to boot up normally. Q. Re-check your mainboard manual and all PSU connections to your mainboard to be sure that nothing is missing (e.g. 12V ATX 4-pin/6-pin connector). If you can provoke shutdowns with Prime95, then consider buying new hardware -- a stable system should run Prime95 for 24h without any errors. Prime95 mentions errors in the log when they occur and gives a summary after the stress test was stopped manually (e.g. "0 errors, 0 warnings", if all is fine) – speakr A. Re-checked, there are no more PSU connectors that I can physically connect, except the one ATX 4-pin (there are 2 that power the CPU) that I disconnected on purpose, I have reconnected it but the problem persists. Q. With one PC I had a short curcuit. The power button on the front plate had its cables soldered, but not isolated, and the contacts were very close to the metal case. A heavier touch was enough to cause a shutdown. The PC's vibration could be enough – ott-- A. yes, it seems to switch off with even the lightest touch, I switched on the PC, then pulled out the front panel power cable that connects to the motherboard so the power button does not work anymore, after 5 mins of working like that, with the power button completely disconnected, just sitting idle, the PC powered off again, I don't think it's the power button. Q. I wonder if you dare to operate components without the case, that is remove motherboard, power, disk ( just put the motherboard on a wooden desk). Don't bend the adapters when running like that. – ott-- A. yes, I do dare to do that, but only tomorrow, too tired/late right now.

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  • DNSSEC - Ad Flag not activated

    - by Arancha
    Hi all, I have some doubts regarding DNSSEC. I have one server acting as an Authoritative Name Server and another one as a Cache/Resolver. I'm using Bind 9.7.1-P2 and these are my configuration files: Named.conf (Authoritative Server) // Opciones de configuracion del servidor include "/etc/rndc.key"; controls { inet 127.0.0.1 allow { localhost; } keys { rndc-key; }; }; options{ version "Peticion no permitida/Query not allowed"; hostname "Peticion no permitida/Query not allowed"; server-id "Peticion no permitida/Query not allowed"; directory "/etc/DNS_RIMA"; pid-file "named.pid"; notify yes; #files 65535; dnssec-enable yes; dnssec-validation yes; allow-transfer { 172.23.2.37; 172.23.3.39; }; transfer-format many-answers; transfers-per-ns 5; transfers-in 10; max-transfer-time-in 120; check-names master ignore; listen-on {172.23.2.57; 80.58.102.13; 80.58.102.103; 127.0.0.1; }; }; zone "test.dnssec" { type master; key-directory "keys"; file "db.test.dnssec.signed"; also-notify { 172.23.2.37 ; 172.23.3.39 ; }; allow-transfer { 172.23.2.37 ; 172.23.3.39 ; }; }; test.dnssec zone test.dnssec. 86400 IN SOA ns.test.dnssec. mxadmin.test.dnssec. ( 2010090902 ; serial 21600 ; refresh (6 hours) 3600 ; retry (1 hour) 1814400 ; expire (3 weeks) 172800 ; minimum (2 days) ) 86400 RRSIG SOA 5 2 86400 20101009062248 ( 20100909062248 40665 test.dnssec. eY99laB6PrtETaXLdCS+G8Uq1lIK7d5vxUB1 pAQ9npv/YbvX1pdWZKGojDgPGw8V65Q0zKQo YW1VuBzvwfSRKax+yrjJzvHQGfCZPJWARehK hgLxHOfXLVH7tyndvLD49ZKcWtrop+Tuy4n9 apWWfSJZxCOngwS7zUi0zCTKfPs= ) 86400 NS ns1.test.dnssec. 86400 RRSIG NS 5 2 86400 20101009062248 ( 20100909062248 40665 test.dnssec. lmlP/Mb2qEXPSlajgSDn/CqWk/jokVCmqjeo idNuytxbiFnbCOunzvaYpgvDpEr0CPrwXaDL TSnb/w53tZl7GHRImJo50vwwNZljLzNT6CFw aaQXFc3rDLsXjCi+WF0/Z7meteM4jYdx5nrV Qx9pgur7VPbP88bJOqWCPBev2Ho= ) 172800 NSEC a.test.dnssec. NS SOA RRSIG NSEC DNSKEY 172800 RRSIG NSEC 5 2 172800 20101009062248 ( 20100909062248 40665 test.dnssec. E76ayamsAAz8Zcj7060KY0nTFzHPztM/Pkc5 OM0EcP7C5+ocn4L8M2J0rmR3jxfYvCpOk0BQ Zniqn9Aw41Qk068yJ2dfDPwV5zT0+te0nzwC /awJGPMXLzMj4JejYTlTiKfspGDJCG44F+lb lHXdcUhbjXf3loqMQadZFQ/eSn0= ) 86400 DNSKEY 256 3 5 ( AwEAAbQ8qrNN5vetx/7E1VOgXZ7fLqwG1y/i 55hWGCeLbcS95ratT9A6UospOvPSwPTlrFgF RWP67Pubzbsy7/damS1F1+p4GgBQway52Hd1 8HjdHKKC6kIxna9pOJBRfhCdzAsv9LnpRvrw mDpcFAqhdn5k5RqwcUF1eOZrKjxXjAOr ) ; key id = 40665 86400 DNSKEY 257 3 5 ( AwEAAcd4dxWyTgOuqha0DJADUH0pk5jvnwdM ZhgZaqnayUdeTh8U9WOjOUHdVCGywZS6NTVp xXqhcegWzh2ZR5VN6thuhezt7kbzLNWbPe7m YF29/ZTXB6nmdSxruQlSvYhzkWTaPNtfrUnI UlbDRxUFWQkSHj9LA1TG76FpR6uqOj1sNrWX nPb/Hwp1Sb2Ik4FlifKb/Vu1+/UnclRJgfPm p2HGTeNYpfk15JHBPSYxJ1TuedXQIdkPGlQX ISmAeV1evGomCC/x9DNleDHCszJOptwurzRP Z7wRXcWnbXz1BU8rAqvUZL3M4UgdNRR5LLTz CkRnrlvXYJpgzDtgmQxE9Bs= ) ; key id = 59647 86400 RRSIG DNSKEY 5 2 86400 20101009062248 ( 20100909062248 40665 test.dnssec. sa4W3tvl6n0TkIcq3xzhG17C2O0lRhllrpUd n5Hs6yVo8r7stewP6tm2XscQiAeseDgmv28w s6Mtiz8uPUbrgFRb6SJk7coH2n/2Y3//S9YP NldDFv3luPnnU1TBb3jDsBKIZWHU9yl/cLNA OKUhlMDd40txk+fQi3iiV5Ls9K8= ) 86400 RRSIG DNSKEY 5 2 86400 20101009062248 ( 20100909062248 59647 test.dnssec. b5fz0dEp2co2pVO7biY896XmsJanjQIR69vC MvSF104/9iZk6eGVFi6hsa4aZcXutEjUDESB ynPkDjMWWIIhN6K1jYKGIc/sFKv1IUONRYHF KXGgZhC6aI0B1E4NA9AXLjlBVF60nHdc3iw8 5gTLDjypP3qAZrnzMvdiBopLnVdB25UZYKn8 mGpOuzKqX02TGMCFMlEVtMX4FP/XKAE8UjiQ 5ehC1JvIKIyg/2zM+ot3nmcqqtUfzp/Hweyc aIkl/9wPJPwMedfTqOjfUKFdB+GiZ0Zz16HZ 5MfJui5IGh5Y6Q04kMrnap2V5U7mByTzx/ud V/eFYhmSHGtAXzBjMA== ) a.test.dnssec. 86400 IN A 1.1.1.1 86400 RRSIG A 5 3 86400 20101009062248 ( 20100909062248 40665 test.dnssec. P52N9ypCrYsgS4CFcUmII0xjyE6KNL9ndhzH oU63fHJHQHeQV+fc0Rx8cCmZSzuqk1lSBelV 3Gcl9UNNuCAQ4ORQ/yJkiZ1zn7h93Mep9qsg YEUQJMfk4FLjYW67DHNcuoCnKbDJhZS0ndVf I474k7ZEZJsGslwk/vcIoFnTa4o= ) 172800 NSEC b.test.dnssec. A RRSIG NSEC 172800 RRSIG NSEC 5 3 172800 20101009062248 ( 20100909062248 40665 test.dnssec. TCduf7xPSrWvEAzBO7Kx5haR85yA/lbsswkQ v0QxlskqAqo+9YedGQV+wGblbCIOmkomrYcq u/rXQ5yoQ3SDXd/bw6EFdoQmH8UJOjMc7SdR xY93MjawPB6XXlJsSlbBFPWJwEpILVRhdBFX czdS5VCa1KmhAYZYQp1FY9rMelA= ) b.test.dnssec. 86400 IN A 2.2.2.2 86400 RRSIG A 5 3 86400 20101009062248 ( 20100909062248 40665 test.dnssec. f0M6Tcqe6B09ctaN3BGAit4u4cJE8x3Ik8sh gyMu0GN/lMv/Bo7PB6hgylLam3HXtF1pPAzX oYudXmhU8afPapHMXfUitC1lFQB5ZW052ZC7 JXV9MnGULydz1blj2EdN+JL3Za8SJKM0LrLB XdQ+QUV+A/6N7hUV6usz5YmdBeI= ) 172800 NSEC ns1.test.dnssec. A RRSIG NSEC 172800 RRSIG NSEC 5 3 172800 20101009062248 ( 20100909062248 40665 test.dnssec. sc6v19dcOFVa295/Xf1pKxBhbdpEErY8CTDQ fw2fjJf0Y3wL1Y1Mlr5zi5ShceQwgua+6YHE DWNbAPcXrJ0lLMU4DU5r0sAyBiBCgCavngGk i59W+nv11zuIpPMnlaMHpJVfJrQ+c4z7H9MH 77B0fMRFTUnvAXoq6ag8Q5POITI= ) ns1.test.dnssec. 86400 IN A 3.3.3.3 86400 RRSIG A 5 3 86400 20101009062248 ( 20100909062248 40665 test.dnssec. UQ3hR/++ta1GokxGz8Yh+GomMcA+xhd3z2Ke z0tdFiNfxvGbm85XyCtSqJIo2S/ZLVJUv/mG nGJbicTfJSziKzYZsD7dp0WJiUK3l7lQ/HpP 5FL8SbjlovVYYAG5woW4p3+os28mmCAJA8gP JTywbcREEhFB4cir2M/QVP+9h+Y= ) 172800 NSEC test.dnssec. A RRSIG NSEC 172800 RRSIG NSEC 5 3 172800 20101009062248 ( 20100909062248 40665 test.dnssec. i7F/ezGl/pGXCC6JyVDaxuwdZMAgv9QLxwzi PTgjCG8Sj6pTIxaQkSLwXsoB9gF77WWBANow R2SWdz0Zai2vWnv/NYoNm9ZfRJEQ9NuExeYp rvX/+lLOHvZXN6tUerIQbWAxO2GwdzHoejSn wReUNVr9MxzZUvuJ33Z7X/7s9VQ= ) Named.conf (Cache/Resolver) include "/etc/rndc.key"; controls { inet 127.0.0.1 allow { localhost; } keys { rndc-key; }; }; options{ version "Peticion no permitida/Query not allowed"; hostname "Peticion no permitida/Query not allowed"; server-id "Peticion no permitida/Query not allowed"; directory "/etc/DNS_RIMA"; pid-file "named.pid"; recursion yes; notify no; #DNSSEC dnssec-enable yes; dnssec-validation yes; listen-on {127.0.0.1; 172.23.2.87; 80.58.102.37; 80.58.102.115; }; #listen-on {127.0.0.1; 80.58.102.37; 80.58.102.115; }; allow-query { telefonica; }; allow-transfer { none; }; recursive-clients 40000; max-cache-size 838860800; rrset-order { order fixed;}; max-ncache-ttl 600; }; trusted-keys { "test.dnssec." 257 3 5 "AwEAAcd4dxWyTgOuqha0DJADUH0pk5jvnwdMZhgZaqnayUdeTh8U9WOjOUHdVCGywZS6NTVpxXqhcegWzh2ZR5VN6thuhezt7kbzLNWbPe7mYF29/ZT XB6nmdSxruQlSvYhzkWTaPNtfrUnIUlbDRxUFWQkSHj9LA1TG76FpR6uqOj1sNrWXnPb/Hwp1Sb2Ik4FlifKb/Vu1+/UnclRJgfPmp2HGTeNYpfk15JHBPSYxJ1TuedXQIdkPGlQXIS mAeV1evGomCC/x9DNleDHCszJOptwurzRPZ7wRXcWnbXz1BU8rAqvUZL3M4UgdNRR5LLTzCkRnrlvXYJpgzDtgmQxE9Bs="; }; I have configured a secure zone (test.dnssec) and I'm trying to perform some queries from the resolver to the Name server (172.23.2.57): /usr/local/bin/dig @172.23.2.57 a.test.dnssec +dnssec ; <<>> DiG 9.7.1-P2 <<>> @172.23.2.57 a.test.dnssec +dnssec ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2654 ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 3 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags: do; udp: 4096 ;; QUESTION SECTION: ;a.test.dnssec. IN A ;; ANSWER SECTION: a.test.dnssec. 86400 IN A 1.1.1.1 a.test.dnssec. 86400 IN RRSIG A 5 3 86400 20101009062248 20100909062248 40665 test.dnssec. P52N9ypCrYsgS4CFcUmII0xjyE6KNL9ndhzHoU63fHJHQHeQV+ fc0Rx8 cCmZSzuqk1lSBelV3Gcl9UNNuCAQ4ORQ/yJkiZ1zn7h93Mep9qsgYEUQ JMfk4FLjYW67DHNcuoCnKbDJhZS0ndVfI474k7ZEZJsGslwk/vcIoFnT a4o= ;; AUTHORITY SECTION: test.dnssec. 86400 IN NS ns1.test.dnssec. test.dnssec. 86400 IN RRSIG NS 5 2 86400 20101009062248 20100909062248 40665 test.dnssec. lmlP/Mb2qEXPSlajgSDn/CqWk/jokVCmqjeoidNuytxbiFnbCOunzvaY pgvDpEr0CPrwXaDLTSnb/w53tZl7GHRImJo50vwwNZljLzNT6CFwaaQX Fc3rDLsXjCi+WF0/Z7meteM4jYdx5nrVQx9pgur7VPbP88bJOqWCPBev 2Ho= ;; ADDITIONAL SECTION: ns1.test.dnssec. 86400 IN A 3.3.3.3 ns1.test.dnssec. 86400 IN RRSIG A 5 3 86400 20101009062248 20100909062248 40665 test.dnssec. UQ3hR/++ta1GokxGz8Yh+GomMcA+xhd3z2Kez0tdFiNfxvGbm85XyCtS qJIo2S/ZLVJUv/mGnGJbicTfJSziKzYZsD7dp0WJiUK3l7lQ/HpP5FL8 SbjlovVYYAG5woW4p3+os28mmCAJA8gPJTywbcREEhFB4cir2M/QVP+9 h+Y= ;; Query time: 1 msec ;; SERVER: 172.23.2.57#53(172.23.2.57) ;; WHEN: Thu Sep 9 09:47:14 2010 ;; MSG SIZE rcvd: 605 I obtain the right answer along with the RRSIG records, but the problem is that I'm not seeing the ad flag activated. Any idea about what is wrong????

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  • Will these instructions work when turning of journaling on a n ext4 SSD?

    - by snowlord
    I have an Acer Aspire One with an SSD for storage. I recently installed Ubuntu on it and chose ext4 for my filesystem. Then I read that journaling on an SSD isn't the best idea, so I will try to disable journaling and I have found these intstructions (from http://fenidik.blogspot.com/2010/03/ext4-disable-journal.html): # Create ext4 fs on /dev/sda10 disk mkfs.ext4 /dev/sda10 # Enable writeback mode. This mode will typically provide the best ext4 performance. tune2fs -o journal_data_writeback /dev/sda10 # Delete has_journal option tune2fs -O ^has_journal /dev/sda10 # Required fsck e2fsck -f /dev/sda10 # Check fs options dumpe2fs /dev/sda10 |more For more performance add fstab opions: data=writeback,noatime,nodiratime i.e: /dev/sda10 /opt ext4 defaults,data=writeback,noatime,nodiratime 0 0 I will use them on my boot partition. Are there any particularly bad parts here, or are there any missing steps? Will my boot partition be fit for being on an SSD after this? Or should I consider switching to ext2, or even reinstall it all and choose ext2 at partitioning time (I'd rather not though, since I've configured quite some stuff already)?

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  • Mac Backup Plan

    - by Chuy77
    I'm reviewing my backup plan and would appreciate any thoughts about what more I should do (if anything) to make sure I'm properly covered in case of all hell breaking loose. :-) I have one machine. 1) I run a nightly clone with SuperDuper. I alternate the clone drive weekly so I have two clones, one never more than a week old. 2) I use BackBlaze as a sort of Time Machine in the cloud. It runs all the time and keeps everything on my machine backed up online. 3) I sync all my 1Password logins, etc. to my iPhone once a week. ...And that's it. I feel pretty covered. But I'm always reading stuff like this: http://www.43folders.com/2010/03/15/yes-another-backup-lecture And that doesn't even mention online backup, and seems like a huge pain in the behind. But maybe I'm being naive? Should I have more backups? Thanks for any feedback. I really appreciate it.

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  • Access keystore on Sun ONE Webserver 6.1 for 2048 bit key length SSL

    - by George Bailey
    We want to get 2048 bit key length CSR requests. The browser based GUI provides us with a 1024 bit CSR and I don't know how to change that. It seems that 1024 bit key lengths will no longer supported by SSL companies. (Lower cost options only support 2048 bit. Thawte who is much more expensive say they accept 1024 for only one or two year certificates, but not 3). The legacy systems in question are running Sun ONE Webserver 6.1. Upgrading would be time consuming and we would rather not have to do that right now. We will be phasing these out but it will take awhile, so... Got it!! http://middlewarekb.wordpress.com/2010/06/30/how-to-generate-2048-bit-keypair-using-sun-one-or-iplanet-6-1-servers/ It is for the same version webserver I am using. /opt/SUNWwbsvr/bin/https/admin/bin/certutil -R -s "CN=sub.domain.ext,OU=org unit,O=company name,L=city,ST=spelled state,C=US,E=email" -a -k rsa -g 2048 -v 12 -d /opt/SUNWwbsvr/alias -P https-sub.domain.ext-hostname- -Z SHA1 Previous efforts edited out.

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  • How to configure IIS 7.5 to allow special chars in Url for ASP.NET 3.5?

    - by Sebastian P.R. Gingter
    I'm trying to configure my IIS 7.5 to allow specials chars in the url for ASP.NET. This is important to support wide-spread legacy url's on a new system. Sample url: http://mydomain.com/FileWith%inTheName.html This would be encoded in the url and requested as http://mydomain.com/FileWith25%inTheName.html This simply works, when creating a new web in IIS 7.5, placing a file with the percentage sign in the file name in the web root and pointing the browser to it. This does not work, however, when the web site is an ASP.NET application. ASP.NET always returns a 400.0 - Bad Request error in the WindowsAuthentication module from the StaticFile handler, when pointing to that url. It however displays the requested url correctly and also resolves correctly to the correct physical file (the information from the field 'Physical Path' from the Server error page points to the physically available file). There are hints on how to enable this, so I followed the instructions on these websites step by step: http://dirk.net/2008/06/09/ampersand-the-request-url-in-iis7/ http://adorr.net/2010/01/configure-iis-to-accept-url-with-special-characters.html The second one actually sums up the information from the first post and adds some more information about x64 systems (we're running x64) and on an additional web.config change for this. I tried all that, and still can't get this running from an asp.net web application. And yes: I rebooted after applying the registry changes. So, what do I have to do in addition to the settings described in above posts, to support the legacy url's which contain percentage characters? Additional info: Application Pool mode is integrated. Push after some days. No idea anyone?

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  • Clarification on signals (sighup), jobs, and the controlling terminal

    - by asolberg
    So I've read two different perspectives and I'm trying to figure out which one is right. 1) Some sources online say that signals sent from the controlling terminal are ONLY sent to the foreground process group. That means if want a process to continue running in the background when you logout it is sufficient to simply suspend the job (ctrl-Z) and resume it in the background (bg). Then you can log out and it will continue to run because SIGHUP is only sent to the foreground job. See: http://blog.nelhage.com/2010/01/a-brief-introduction-to-termios-signaling-and-job-control/ ...In addition, if any signal-generating character is read by a terminal, it generates the appropriate signal to the foreground process group.... 2) Other sources claim you need to use the "nohup" command at the time the program is executed, or failing that, issue a "disown" command during execution to remove it from the jobs table that listens for SIGHUP. They say if you don't do this when you logout your process will also exit even if its running in a background process group. For example: http://docstore.mik.ua/orelly/unix3/upt/ch23_11.htm ...If I log out anyway, the shell sends my background job a HUP signal... In my own experiments with Ubuntu linux it seems like 1) is correct. I executed a command: "sleep 20 &" then logged out, logged back in and pressed did a "ps aux". Sure enough the sleep command was still running. So then why is it that so many people seem to believe number 2? And if all you have to do is place a job in the background to keep it running why do so many people use "nohup" and "disown?"

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  • PHP cannot connect to MySQL

    - by yogal
    Hello, I recently installed Apache 2 + PHP 5.3.1 + MySQL 5.1.44 on my Windows 7 64bit machine following this guide: http://sleeplessgeek.blogspot.com/2010/01/setting-up-apache-php-mysql-phpmyadmin.html It all went fine, php is working great (even with XDebug) but I cannot connect to mysql server. A simple script I wrote to test connection (yes, root has no pass): $username = "root"; $password = ""; $database = "test"; $hostname = "localhost"; $conn = mysql_connect($hostname, $username, $password) or die("Unable to connect to MySQL Database!!"); It prints this error after 60sec of timeout: Warning: mysql_connect() [function.mysql-connect]: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. I can connect to mysql using cmdmysql -h localhost -u root Services are working properly. There also seems to be a problem with PhpMyAdmin (using 3.2.5). As soon as I type user and pass the page loads and turns blank (content-lenght in headers is 0 but status code is 302 Found). Looks like something wrong with cookies (my auth method). I hope someone has a clue, it has to be something dumb simple I missed. Thanks in advance.

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  • Adding custom service to nagiosgraph

    - by ravloony
    I have successfully added nagiosgraph to our nagios installation. I also added a memory checker plugin, from here : http://blog.vergiss-blackjack.de/2010/04/nagios-plugin-to-check-memory-consumption/. However I can't seem to get the graph of this service to be output by nagiosgraph. The plugin returns a single line like this: 31% (3785 of 11903 MB) used so i added a rule like this to the map file: /output:(\d+)% \((\d+) of (\d+) MB\) used/ and push @s, ['Mem', ['Percentage', 'GUAGE', $1], ['Used', 'GUAGE', $2], ['Total', 'GUAGE', $3] ]; I have also read this : http://www.mail-archive.com/[email protected]/msg36835.html and made sure that process_performance_data=1 in the nagios conf file. So far I have no graph for the Mem service on any host, and no rrd file either. I am unsure how to proceed to get this working. The documentation is rather difficult to follow and I haven't managed yet to understand it enough to do this. Can anyone point me to a tutorial, or some documentation which explains the steps needed to get a service noticed and graphed by nagiosgraph?

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  • Route specific network traffic through vpn in virtualbox guest

    - by Sander
    I am running OSX with a windows server 2008 guest in Virtualbox. My goal is to route some of the network traffic in the host through the server guest. This is because the win2008 server has a VPN connection to my workplace using a Smartcard solution which can not operate on OSX. My current set-up is like this: OSX (Host): connected to the internet via en01 Win2008 (Guest): connected to the internet using NAT (lan1 in guest) has a SSTP VPN connection to my workplace is connected to the guest using an Host Only Adapter vboxnet0 (LAN2 in guest) The important part is about the host (OSX). Primarily I want all network traffic to just go through en01. However, all traffic which can only be accessed through the VPN must go through the guest and through the VPN. I have one specific FQDN which can only be accessed through the VPN (say corp.mycompany.com). I do not know much about networking. I thought I would be able to get it to work by bridging together LAN2 and LAN1 but this didn't seem to work this: http://archives.aidanfindlater.com/blog/2010/02/03/use-vpn-for-specific-sites-on-mac-os-x/ using a loopback adapter on WinXP (when I did not have win2008 yet, but this doesn't work because I can't create a PPTP connection) And I've also read about Routing and Remote Access but I have no idea on how to use this. Can someone help me in the right direction?

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  • Will these instructions work when turning of journaling on an ext4 SSD?

    - by snowlord
    I have an Acer Aspire One with an SSD for storage. I recently installed Ubuntu on it and chose ext4 for my filesystem. Then I read that journaling on an SSD isn't the best idea, so I will try to disable journaling and I have found these intstructions (from http://fenidik.blogspot.com/2010/03/ext4-disable-journal.html): # Create ext4 fs on /dev/sda10 disk mkfs.ext4 /dev/sda10 # Enable writeback mode. This mode will typically provide the best ext4 performance. tune2fs -o journal_data_writeback /dev/sda10 # Delete has_journal option tune2fs -O ^has_journal /dev/sda10 # Required fsck e2fsck -f /dev/sda10 # Check fs options dumpe2fs /dev/sda10 |more For more performance add fstab opions: data=writeback,noatime,nodiratime i.e: /dev/sda10 /opt ext4 defaults,data=writeback,noatime,nodiratime 0 0 I will use them on my boot partition. Are there any particularly bad parts here, or are there any missing steps? Will my boot partition be fit for being on an SSD after this? Or should I consider switching to ext2, or even reinstall it all and choose ext2 at partitioning time (I'd rather not though, since I've configured quite some stuff already)?

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  • User authentication -- username mismatch in IIS in ASP.NET application

    - by Cory Larson
    Last week, an employee's Active Directory username was changed (or a new one was created for them). For the purposes of this example, let's assume these usernames: Old: Domain\11111 New: Domain\22222 When this user now logs in using their new username, and attempts to browse to any one of a number of ASP.NET applications using only Windows Authentication (no Anonymous enabled), the system authenticates but our next layer of database-driven permissions prevents them from being authorized. We tracked it down to a mismatch of usernames between their logon account and who IIS thinks they are. Below are the outputs of several ASP.NET variables from apps running in a Windows 2008 IIS7.5 environment: Request.ServerVariables["AUTH_TYPE"]: Negotiate Request.ServerVariables["AUTH_USER"]: Domain\11111 Request.ServerVariables["LOGON_USER"]: Domain\22222 Request.ServerVariables["REMOTE_USER"]: Domain\11111 HttpContext.Current.User.Identity.Name: Domain\11111 System.Threading.Thread.CurrentPrincipal.Identity.Name: Domain\11111 From the above, I can see that only the LOGON_USER server variable has the correct value, which is the account the user used to log on to their machine. However, we use the "AUTH_USER" variable for looking up the database permissions. In a separate testing environment (completely different server: Windows 2003, IIS6), all of the above variables show "Domain\22222". So this seems to be a server-specific issue, like the credentials are somehow getting cached either on their machine or on the server (the former seems more plausible). So the question is: how do I confirm whether it's the user's machine or the server that is botching the request? How should I go about fixing this? I looked at the following two resources and will be giving the first one a try shortly: http://www.interworks.com/blogs/jvalente/2010/02/02/removing-saved-credentials-passwords-windows-xp-windows-vista-or-windows-7 http://stackoverflow.com/questions/2325005/classic-asp-request-servervariableslogon-user-returning-wrong-username/5299080#5299080 Thanks.

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  • Windows 2003 DC to Windows 2008 R2 DC with same name and same IP

    - by TheCleaner
    Environment = Windows 2003 native domain with 8 DCs I've got an old domain controller that is running 2003, CA Enterprise role, DHCP, DNS, a few GPO scripts that point to shares on it, and some other minor functions. All our servers point to it as their primary DNS, and there's lots of references to its IP or name throughout the domain at this point (8+ years later). I really don't feel like manually changing all of this, it would be a pretty massive undertaking. I want to follow this guide: http://msmvps.com/blogs/acefekay/archive/2010/10/09/remove-an-old-dc-and-introduce-a-new-dc-with-the-same-name-and-ip-address.aspx to hopefully end up with basically an "in-place upgrade" so to say. I considered just doing a P2V of the box, but we don't really want to keep it around running 2003 to be honest. I also considered using a CNAME and adding a 2nd IP (the old one) but again, it seemed like it would be cleaner using the attached link. My actual question: Any gotchas or big caution signs when doing what the link suggests? Anyone gone down this road and have advice on how to proceed?

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  • Postfix + Exchange + ActiveDirectory; How to mix them

    - by itwb
    My client has got many sub-offices, and one head office. The headoffice has a domain name: business.com All users in the many sub-offices need to have a headoffice email address: [email protected] Anyone not in the head office will need the email forwarded to an external email address. All users in the head office will have their email delivered to Microsoft Exchange. Users are listed in Active Directory under two different OU's: HeadOffice or SubOffice. Is this something able to be configured? I've done some googling, but I can't find any examples or businesses set up this way. Edit: Postfix will accept all email, will need to determine to forward the email to an external account or alternatively have it delivered to MS Exchange. I've done some reading about MS Exchange and that you can 'mail-enable' contacts for forwarding - but I don't know if each AD account requires an Exchange CAL? The end goal is to forward email to external accounts to sub offices or accept email for head office. Maybe I don't need to worry about Postfix to perform this task..... http://www.windowsitpro.com/article/exchange-server-2010/exchange-server-licensing-some-of-your-questions-answered "What about client access licenses (CALs)? You need one CAL per user who will connect to Exchange. Although it might not be 100 percent precise, I prefer to think of it as one CAL per mailbox; there are exceptions for users outside your organization, automated tools that use mailboxes, and so on. Exchange doesn't enforce this limit, so it's on you to ensure that you have the correct number of CALs for the set of clients you support."

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  • Jailkit not locking down SFTP, working for SSH

    - by doublesharp
    I installed jailkit on my CentOS 5.8 server, and configured it according to the online guides that I found. These are the commands that were executed as root: mkdir /var/jail jk_init -j /var/jail extshellplusnet jk_init -j /var/jail sftp adduser testuser; passwd testuser jk_jailuser -j /var/jail testuser I then edited /var/jail/etc/passwd to change the login shell for testuser to be /bin/bash to give them access to a full bash shell via SSH. Next I edited /var/jail/etc/jailkit/jk_lsh.ini to look like the following (not sure if this is correct) [testuser] paths= /usr/bin, /usr/lib/ executables= /usr/bin/scp, /usr/lib/openssh/sftp-server, /usr/bin/sftp The testuser is able to connect via SSH and is limited to only view the chroot jail directory, and is also able to log in via SFTP, however the entire file system is visible and can be traversed. SSH Output: > ssh testuser@server Password: Last login: Sat Oct 20 03:26:19 2012 from x.x.x.x bash-3.2$ pwd /home/testuser SFTP Output: > sftp testuser@server Password: Connected to server. sftp> pwd Remote working directory: /var/jail/home/testuser What can be done to lock down SFTP access to the jail? FWIW, I mostly used this as a guide: http://digitalpatch.blogspot.com.ar/2010/03/openssh-daemon-hardening-part-3-setup.html

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  • Glassfish and SSL [closed]

    - by Richard
    I'm struggling to get SSL working on Glassfish 3.1.1. I've been following tutorials like http://javadude.wordpress.com/2010/04/06/getting-started-with-glassfish-v3-and-ssl/ and SO posts like this Issues with setting up SSL on Glassfish v3 The above links are for information only. I've summarised what I've done below. As far as I can tell I'm doing everything correctly but I'm getting this error: SSL configuration is invalid due to No available certificate or key corresponds to the SSL cipher suites which are enabled Some background of what I have done: My cert is from GoDaddy. I generated the CSR from a new keystore (keystore.jks), then imported the resulting certs back into the same keystore and set the keystore password to the same pwd as the GF master password. Then created a new SSL listener in GF and pointed it at my keystore file (which I copied into domains/domain1/config). Set the Nickname to the alias of my cert (which is something liem 'mydomain.org' i.e. the name that I get when I run keytool -list. In my ciphers section in the network listeners page, I leave the defaults in place (empty, which means all ciphers are available I think). In domain.xml I've replaced all instances of s1as to 'mydomain.org'. This is the question: What exactly is causing the error highlighted? I'm guessing it's a mismatch between my listener config and aliases in my keystore, or something similar, but I'm not really sure what. Thanks

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  • A free standing ASP.NET Pager Web Control

    - by Rick Strahl
    Paging in ASP.NET has been relatively easy with stock controls supporting basic paging functionality. However, recently I built an MVC application and one of the things I ran into was that I HAD TO build manual paging support into a few of my pages. Dealing with list controls and rendering markup is easy enough, but doing paging is a little more involved. I ended up with a small but flexible component that can be dropped anywhere. As it turns out the task of creating a semi-generic Pager control for MVC was fairly easily. Now I’m back to working in Web Forms and thought to myself that the way I created the pager in MVC actually would also work in ASP.NET – in fact quite a bit easier since the whole thing can be conveniently wrapped up into an easily reusable control. A standalone pager would provider easier reuse in various pages and a more consistent pager display regardless of what kind of 'control’ the pager is associated with. Why a Pager Control? At first blush it might sound silly to create a new pager control – after all Web Forms has pretty decent paging support, doesn’t it? Well, sort of. Yes the GridView control has automatic paging built in and the ListView control has the related DataPager control. The built in ASP.NET paging has several issues though: Postback and JavaScript requirements If you look at paging links in ASP.NET they are always postback links with javascript:__doPostback() calls that go back to the server. While that works fine and actually has some benefit like the fact that paging saves changes to the page and post them back, it’s not very SEO friendly. Basically if you use javascript based navigation nosearch engine will follow the paging links which effectively cuts off list content on the first page. The DataPager control does support GET based links via the QueryStringParameter property, but the control is effectively tied to the ListView control (which is the only control that implements IPageableItemContainer). DataSource Controls required for Efficient Data Paging Retrieval The only way you can get paging to work efficiently where only the few records you display on the page are queried for and retrieved from the database you have to use a DataSource control - only the Linq and Entity DataSource controls  support this natively. While you can retrieve this data yourself manually, there’s no way to just assign the page number and render the pager based on this custom subset. Other than that default paging requires a full resultset for ASP.NET to filter the data and display only a subset which can be very resource intensive and wasteful if you’re dealing with largish resultsets (although I’m a firm believer in returning actually usable sets :-}). If you use your own business layer that doesn’t fit an ObjectDataSource you’re SOL. That’s a real shame too because with LINQ based querying it’s real easy to retrieve a subset of data that is just the data you want to display but the native Pager functionality doesn’t support just setting properties to display just the subset AFAIK. DataPager is not Free Standing The DataPager control is the closest thing to a decent Pager implementation that ASP.NET has, but alas it’s not a free standing component – it works off a related control and the only one that it effectively supports from the stock ASP.NET controls is the ListView control. This means you can’t use the same data pager formatting for a grid and a list view or vice versa and you’re always tied to the control. Paging Events In order to handle paging you have to deal with paging events. The events fire at specific time instances in the page pipeline and because of this you often have to handle data binding in a way to work around the paging events or else end up double binding your data sources based on paging. Yuk. Styling The GridView pager is a royal pain to beat into submission for styled rendering. The DataPager control has many more options and template layout and it renders somewhat cleaner, but it too is not exactly easy to get a decent display for. Not a Generic Solution The problem with the ASP.NET controls too is that it’s not generic. GridView, DataGrid use their own internal paging, ListView can use a DataPager and if you want to manually create data layout – well you’re on your own. IOW, depending on what you use you likely have very different looking Paging experiences. So, I figured I’ve struggled with this once too many and finally sat down and built a Pager control. The Pager Control My goal was to create a totally free standing control that has no dependencies on other controls and certainly no requirements for using DataSource controls. The idea is that you should be able to use this pager control without any sort of data requirements at all – you should just be able to set properties and be able to display a pager. The Pager control I ended up with has the following features: Completely free standing Pager control – no control or data dependencies Complete manual control – Pager can render without any data dependency Easy to use: Only need to set PageSize, ActivePage and TotalItems Supports optional filtering of IQueryable for efficient queries and Pager rendering Supports optional full set filtering of IEnumerable<T> and DataTable Page links are plain HTTP GET href Links Control automatically picks up Page links on the URL and assigns them (automatic page detection no page index changing events to hookup) Full CSS Styling support On the downside there’s no templating support for the control so the layout of the pager is relatively fixed. All elements however are stylable and there are options to control the text, and layout options such as whether to display first and last pages and the previous/next buttons and so on. To give you an idea what the pager looks like, here are two differently styled examples (all via CSS):   The markup for these two pagers looks like this: <ww:Pager runat="server" id="ItemPager" PageSize="5" PageLinkCssClass="gridpagerbutton" SelectedPageCssClass="gridpagerbutton-selected" PagesTextCssClass="gridpagertext" CssClass="gridpager" RenderContainerDiv="true" ContainerDivCssClass="gridpagercontainer" MaxPagesToDisplay="6" PagesText="Item Pages:" NextText="next" PreviousText="previous" /> <ww:Pager runat="server" id="ItemPager2" PageSize="5" RenderContainerDiv="true" MaxPagesToDisplay="6" /> The latter example uses default style settings so it there’s not much to set. The first example on the other hand explicitly assigns custom styles and overrides a few of the formatting options. Styling The styling is based on a number of CSS classes of which the the main pager, pagerbutton and pagerbutton-selected classes are the important ones. Other styles like pagerbutton-next/prev/first/last are based on the pagerbutton style. The default styling shown for the red outlined pager looks like this: .pagercontainer { margin: 20px 0; background: whitesmoke; padding: 5px; } .pager { float: right; font-size: 10pt; text-align: left; } .pagerbutton,.pagerbutton-selected,.pagertext { display: block; float: left; text-align: center; border: solid 2px maroon; min-width: 18px; margin-left: 3px; text-decoration: none; padding: 4px; } .pagerbutton-selected { font-size: 130%; font-weight: bold; color: maroon; border-width: 0px; background: khaki; } .pagerbutton-first { margin-right: 12px; } .pagerbutton-last,.pagerbutton-prev { margin-left: 12px; } .pagertext { border: none; margin-left: 30px; font-weight: bold; } .pagerbutton a { text-decoration: none; } .pagerbutton:hover { background-color: maroon; color: cornsilk; } .pagerbutton-prev { background-image: url(images/prev.png); background-position: 2px center; background-repeat: no-repeat; width: 35px; padding-left: 20px; } .pagerbutton-next { background-image: url(images/next.png); background-position: 40px center; background-repeat: no-repeat; width: 35px; padding-right: 20px; margin-right: 0px; } Yup that’s a lot of styling settings although not all of them are required. The key ones are pagerbutton, pager and pager selection. The others (which are implicitly created by the control based on the pagerbutton style) are for custom markup of the ‘special’ buttons. In my apps I tend to have two kinds of pages: Those that are associated with typical ‘grid’ displays that display purely tabular data and those that have a more looser list like layout. The two pagers shown above represent these two views and the pager and gridpager styles in my standard style sheet reflect these two styles. Configuring the Pager with Code Finally lets look at what it takes to hook up the pager. As mentioned in the highlights the Pager control is completely independent of other controls so if you just want to display a pager on its own it’s as simple as dropping the control and assigning the PageSize, ActivePage and either TotalPages or TotalItems. So for this markup: <ww:Pager runat="server" id="ItemPagerManual" PageSize="5" MaxPagesToDisplay="6" /> I can use code as simple as: ItemPagerManual.PageSize = 3; ItemPagerManual.ActivePage = 4;ItemPagerManual.TotalItems = 20; Note that ActivePage is not required - it will automatically use any Page=x query string value and assign it, although you can override it as I did above. TotalItems can be any value that you retrieve from a result set or manually assign as I did above. A more realistic scenario based on a LINQ to SQL IQueryable result is even easier. In this example, I have a UserControl that contains a ListView control that renders IQueryable data. I use a User Control here because there are different views the user can choose from with each view being a different user control. This incidentally also highlights one of the nice features of the pager: Because the pager is independent of the control I can put the pager on the host page instead of into each of the user controls. IOW, there’s only one Pager control, but there are potentially many user controls/listviews that hold the actual display data. The following code demonstrates how to use the Pager with an IQueryable that loads only the records it displays: protected voidPage_Load(objectsender, EventArgs e) {     Category = Request.Params["Category"] ?? string.Empty;     IQueryable<wws_Item> ItemList = ItemRepository.GetItemsByCategory(Category);     // Update the page and filter the list down     ItemList = ItemPager.FilterIQueryable<wws_Item>(ItemList); // Render user control with a list view Control ulItemList = LoadControl("~/usercontrols/" + App.Configuration.ItemListType + ".ascx"); ((IInventoryItemListControl)ulItemList).InventoryItemList = ItemList; phItemList.Controls.Add(ulItemList); // placeholder } The code uses a business object to retrieve Items by category as an IQueryable which means that the result is only an expression tree that hasn’t execute SQL yet and can be further filtered. I then pass this IQueryable to the FilterIQueryable() helper method of the control which does two main things: Filters the IQueryable to retrieve only the data displayed on the active page Sets the Totaltems property and calculates TotalPages on the Pager and that’s it! When the Pager renders it uses those values, plus the PageSize and ActivePage properties to render the Pager. In addition to IQueryable there are also filter methods for IEnumerable<T> and DataTable, but these versions just filter the data by removing rows/items from the entire already retrieved data. Output Generated and Paging Links The output generated creates pager links as plain href links. Here’s what the output looks like: <div id="ItemPager" class="pagercontainer"> <div class="pager"> <span class="pagertext">Pages: </span><a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=1" class="pagerbutton" />1</a> <a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=2" class="pagerbutton" />2</a> <a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=3" class="pagerbutton" />3</a> <span class="pagerbutton-selected">4</span> <a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=5" class="pagerbutton" />5</a> <a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=6" class="pagerbutton" />6</a> <a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=20" class="pagerbutton pagerbutton-last" />20</a>&nbsp;<a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=3" class="pagerbutton pagerbutton-prev" />Prev</a>&nbsp;<a href="http://localhost/WestWindWebStore/itemlist.aspx?Page=5" class="pagerbutton pagerbutton-next" />Next</a></div> <br clear="all" /> </div> </div> The links point back to the current page and simply append a Page= page link into the page. When the page gets reloaded with the new page number the pager automatically detects the page number and automatically assigns the ActivePage property which results in the appropriate page to be displayed. The code shown in the previous section is all that’s needed to handle paging. Note that HTTP GET based paging is different than the Postback paging ASP.NET uses by default. Postback paging preserves modified page content when clicking on pager buttons, but this control will simply load a new page – no page preservation at this time. The advantage of not using Postback paging is that the URLs generated are plain HTML links that a search engine can follow where __doPostback() links are not. Pager with a Grid The pager also works in combination with grid controls so it’s easy to bypass the grid control’s paging features if desired. In the following example I use a gridView control and binds it to a DataTable result which is also filterable by the Pager control. The very basic plain vanilla ASP.NET grid markup looks like this: <div style="width: 600px; margin: 0 auto;padding: 20px; "> <asp:DataGrid runat="server" AutoGenerateColumns="True" ID="gdItems" CssClass="blackborder" style="width: 600px;"> <AlternatingItemStyle CssClass="gridalternate" /> <HeaderStyle CssClass="gridheader" /> </asp:DataGrid> <ww:Pager runat="server" ID="Pager" CssClass="gridpager" ContainerDivCssClass="gridpagercontainer" PageLinkCssClass="gridpagerbutton" SelectedPageCssClass="gridpagerbutton-selected" PageSize="8" RenderContainerDiv="true" MaxPagesToDisplay="6" /> </div> and looks like this when rendered: using custom set of CSS styles. The code behind for this code is also very simple: protected void Page_Load(object sender, EventArgs e) { string category = Request.Params["category"] ?? ""; busItem itemRep = WebStoreFactory.GetItem(); var items = itemRep.GetItemsByCategory(category) .Select(itm => new {Sku = itm.Sku, Description = itm.Description}); // run query into a DataTable for demonstration DataTable dt = itemRep.Converter.ToDataTable(items,"TItems"); // Remove all items not on the current page dt = Pager.FilterDataTable(dt,0); // bind and display gdItems.DataSource = dt; gdItems.DataBind(); } A little contrived I suppose since the list could already be bound from the list of elements, but this is to demonstrate that you can also bind against a DataTable if your business layer returns those. Unfortunately there’s no way to filter a DataReader as it’s a one way forward only reader and the reader is required by the DataSource to perform the bindings.  However, you can still use a DataReader as long as your business logic filters the data prior to rendering and provides a total item count (most likely as a second query). Control Creation The control itself is a pretty brute force ASP.NET control. Nothing clever about this other than some basic rendering logic and some simple calculations and update routines to determine which buttons need to be shown. You can take a look at the full code from the West Wind Web Toolkit’s Repository (note there are a few dependencies). To give you an idea how the control works here is the Render() method: /// <summary> /// overridden to handle custom pager rendering for runtime and design time /// </summary> /// <param name="writer"></param> protected override void Render(HtmlTextWriter writer) { base.Render(writer); if (TotalPages == 0 && TotalItems > 0) TotalPages = CalculateTotalPagesFromTotalItems(); if (DesignMode) TotalPages = 10; // don't render pager if there's only one page if (TotalPages < 2) return; if (RenderContainerDiv) { if (!string.IsNullOrEmpty(ContainerDivCssClass)) writer.AddAttribute("class", ContainerDivCssClass); writer.RenderBeginTag("div"); } // main pager wrapper writer.WriteBeginTag("div"); writer.AddAttribute("id", this.ClientID); if (!string.IsNullOrEmpty(CssClass)) writer.WriteAttribute("class", this.CssClass); writer.Write(HtmlTextWriter.TagRightChar + "\r\n"); // Pages Text writer.WriteBeginTag("span"); if (!string.IsNullOrEmpty(PagesTextCssClass)) writer.WriteAttribute("class", PagesTextCssClass); writer.Write(HtmlTextWriter.TagRightChar); writer.Write(this.PagesText); writer.WriteEndTag("span"); // if the base url is empty use the current URL FixupBaseUrl(); // set _startPage and _endPage ConfigurePagesToRender(); // write out first page link if (ShowFirstAndLastPageLinks && _startPage != 1) { writer.WriteBeginTag("a"); string pageUrl = StringUtils.SetUrlEncodedKey(BaseUrl, QueryStringPageField, (1).ToString()); writer.WriteAttribute("href", pageUrl); if (!string.IsNullOrEmpty(PageLinkCssClass)) writer.WriteAttribute("class", PageLinkCssClass + " " + PageLinkCssClass + "-first"); writer.Write(HtmlTextWriter.SelfClosingTagEnd); writer.Write("1"); writer.WriteEndTag("a"); writer.Write("&nbsp;"); } // write out all the page links for (int i = _startPage; i < _endPage + 1; i++) { if (i == ActivePage) { writer.WriteBeginTag("span"); if (!string.IsNullOrEmpty(SelectedPageCssClass)) writer.WriteAttribute("class", SelectedPageCssClass); writer.Write(HtmlTextWriter.TagRightChar); writer.Write(i.ToString()); writer.WriteEndTag("span"); } else { writer.WriteBeginTag("a"); string pageUrl = StringUtils.SetUrlEncodedKey(BaseUrl, QueryStringPageField, i.ToString()).TrimEnd('&'); writer.WriteAttribute("href", pageUrl); if (!string.IsNullOrEmpty(PageLinkCssClass)) writer.WriteAttribute("class", PageLinkCssClass); writer.Write(HtmlTextWriter.SelfClosingTagEnd); writer.Write(i.ToString()); writer.WriteEndTag("a"); } writer.Write("\r\n"); } // write out last page link if (ShowFirstAndLastPageLinks && _endPage < TotalPages) { writer.WriteBeginTag("a"); string pageUrl = StringUtils.SetUrlEncodedKey(BaseUrl, QueryStringPageField, TotalPages.ToString()); writer.WriteAttribute("href", pageUrl); if (!string.IsNullOrEmpty(PageLinkCssClass)) writer.WriteAttribute("class", PageLinkCssClass + " " + PageLinkCssClass + "-last"); writer.Write(HtmlTextWriter.SelfClosingTagEnd); writer.Write(TotalPages.ToString()); writer.WriteEndTag("a"); } // Previous link if (ShowPreviousNextLinks && !string.IsNullOrEmpty(PreviousText) && ActivePage > 1) { writer.Write("&nbsp;"); writer.WriteBeginTag("a"); string pageUrl = StringUtils.SetUrlEncodedKey(BaseUrl, QueryStringPageField, (ActivePage - 1).ToString()); writer.WriteAttribute("href", pageUrl); if (!string.IsNullOrEmpty(PageLinkCssClass)) writer.WriteAttribute("class", PageLinkCssClass + " " + PageLinkCssClass + "-prev"); writer.Write(HtmlTextWriter.SelfClosingTagEnd); writer.Write(PreviousText); writer.WriteEndTag("a"); } // Next link if (ShowPreviousNextLinks && !string.IsNullOrEmpty(NextText) && ActivePage < TotalPages) { writer.Write("&nbsp;"); writer.WriteBeginTag("a"); string pageUrl = StringUtils.SetUrlEncodedKey(BaseUrl, QueryStringPageField, (ActivePage + 1).ToString()); writer.WriteAttribute("href", pageUrl); if (!string.IsNullOrEmpty(PageLinkCssClass)) writer.WriteAttribute("class", PageLinkCssClass + " " + PageLinkCssClass + "-next"); writer.Write(HtmlTextWriter.SelfClosingTagEnd); writer.Write(NextText); writer.WriteEndTag("a"); } writer.WriteEndTag("div"); if (RenderContainerDiv) { if (RenderContainerDivBreak) writer.Write("<br clear=\"all\" />\r\n"); writer.WriteEndTag("div"); } } As I said pretty much brute force rendering based on the control’s property settings of which there are quite a few: You can also see the pager in the designer above. unfortunately the VS designer (both 2010 and 2008) fails to render the float: left CSS styles properly and starts wrapping after margins are applied in the special buttons. Not a big deal since VS does at least respect the spacing (the floated elements overlay). Then again I’m not using the designer anyway :-}. Filtering Data What makes the Pager easy to use is the filter methods built into the control. While this functionality is clearly not the most politically correct design choice as it violates separation of concerns, it’s very useful for typical pager operation. While I actually have filter methods that do something similar in my business layer, having it exposed on the control makes the control a lot more useful for typical databinding scenarios. Of course these methods are optional – if you have a business layer that can provide filtered page queries for you can use that instead and assign the TotalItems property manually. There are three filter method types available for IQueryable, IEnumerable and for DataTable which tend to be the most common use cases in my apps old and new. The IQueryable version is pretty simple as it can simply rely on on .Skip() and .Take() with LINQ: /// <summary> /// <summary> /// Queries the database for the ActivePage applied manually /// or from the Request["page"] variable. This routine /// figures out and sets TotalPages, ActivePage and /// returns a filtered subset IQueryable that contains /// only the items from the ActivePage. /// </summary> /// <param name="query"></param> /// <param name="activePage"> /// The page you want to display. Sets the ActivePage property when passed. /// Pass 0 or smaller to use ActivePage setting. /// </param> /// <returns></returns> public IQueryable<T> FilterIQueryable<T>(IQueryable<T> query, int activePage) where T : class, new() { ActivePage = activePage < 1 ? ActivePage : activePage; if (ActivePage < 1) ActivePage = 1; TotalItems = query.Count(); if (TotalItems <= PageSize) { ActivePage = 1; TotalPages = 1; return query; } int skip = ActivePage - 1; if (skip > 0) query = query.Skip(skip * PageSize); _TotalPages = CalculateTotalPagesFromTotalItems(); return query.Take(PageSize); } The IEnumerable<T> version simply  converts the IEnumerable to an IQuerable and calls back into this method for filtering. The DataTable version requires a little more work to manually parse and filter records (I didn’t want to add the Linq DataSetExtensions assembly just for this): /// <summary> /// Filters a data table for an ActivePage. /// /// Note: Modifies the data set permanently by remove DataRows /// </summary> /// <param name="dt">Full result DataTable</param> /// <param name="activePage">Page to display. 0 to use ActivePage property </param> /// <returns></returns> public DataTable FilterDataTable(DataTable dt, int activePage) { ActivePage = activePage < 1 ? ActivePage : activePage; if (ActivePage < 1) ActivePage = 1; TotalItems = dt.Rows.Count; if (TotalItems <= PageSize) { ActivePage = 1; TotalPages = 1; return dt; } int skip = ActivePage - 1; if (skip > 0) { for (int i = 0; i < skip * PageSize; i++ ) dt.Rows.RemoveAt(0); } while(dt.Rows.Count > PageSize) dt.Rows.RemoveAt(PageSize); return dt; } Using the Pager Control The pager as it is is a first cut I built a couple of weeks ago and since then have been tweaking a little as part of an internal project I’m working on. I’ve replaced a bunch of pagers on various older pages with this pager without any issues and have what now feels like a more consistent user interface where paging looks and feels the same across different controls. As a bonus I’m only loading the data from the database that I need to display a single page. With the preset class tags applied too adding a pager is now as easy as dropping the control and adding the style sheet for styling to be consistent – no fuss, no muss. Schweet. Hopefully some of you may find this as useful as I have or at least as a baseline to build ontop of… Resources The Pager is part of the West Wind Web & Ajax Toolkit Pager.cs Source Code (some toolkit dependencies) Westwind.css base stylesheet with .pager and .gridpager styles Pager Example Page © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  

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  • Building applications with WPF, MVVM and Prism(aka CAG)

    - by skjagini
    In this article I am going to walk through an application using WPF and Prism (aka composite application guidance, CAG) which simulates engaging a taxi (cab).  The rules are simple, the app would have3 screens A login screen to authenticate the user An information screen. A screen to engage the cab and roam around and calculating the total fare Metered Rate of Fare The meter is required to be engaged when a cab is occupied by anyone $3.00 upon entry $0.35 for each additional unit The unit fare is: one-fifth of a mile, when the cab is traveling at 6 miles an hour or more; or 60 seconds when not in motion or traveling at less than 12 miles per hour. Night surcharge of $.50 after 8:00 PM & before 6:00 AM Peak hour Weekday Surcharge of $1.00 Monday - Friday after 4:00 PM & before 8:00 PM New York State Tax Surcharge of $.50 per ride. Example: Friday (2010-10-08) 5:30pm Start at Lexington Ave & E 57th St End at Irving Pl & E 15th St Start = $3.00 Travels 2 miles at less than 6 mph for 15 minutes = $3.50 Travels at more than 12 mph for 5 minutes = $1.75 Peak hour Weekday Surcharge = $1.00 (ride started at 5:30 pm) New York State Tax Surcharge = $0.50 Before we dive into the app, I would like to give brief description about the framework.  If you want to jump on to the source code, scroll all the way to the end of the post. MVVM MVVM pattern is in no way related to the usage of PRISM in your application and should be considered if you are using WPF irrespective of PRISM or not. Lets say you are not familiar with MVVM, your typical UI would involve adding some UI controls like text boxes, a button, double clicking on the button,  generating event handler, calling a method from business layer and updating the user interface, it works most of the time for developing small scale applications. The problem with this approach is that there is some amount of code specific to business logic wrapped in UI specific code which is hard to unit test it, mock it and MVVM helps to solve the exact problem. MVVM stands for Model(M) – View(V) – ViewModel(VM),  based on the interactions with in the three parties it should be called VVMM,  MVVM sounds more like MVC (Model-View-Controller) so the name. Why it should be called VVMM: View – View Model - Model WPF allows to create user interfaces using XAML and MVVM takes it to the next level by allowing complete separation of user interface and business logic. In WPF each view will have a property, DataContext when set to an instance of a class (which happens to be your view model) provides the data the view is interested in, i.e., view interacts with view model and at the same time view model interacts with view through DataContext. Sujith, if view and view model are interacting directly with each other how does MVVM is helping me separation of concerns? Well, the catch is DataContext is of type Object, since it is of type object view doesn’t know exact type of view model allowing views and views models to be loosely coupled. View models aggregate data from models (data access layer, services, etc) and make it available for views through properties, methods etc, i.e., View Models interact with Models. PRISM Prism is provided by Microsoft Patterns and Practices team and it can be downloaded from codeplex for source code,  samples and documentation on msdn.  The name composite implies, to compose user interface from different modules (views) without direct dependencies on each other, again allowing  loosely coupled development. Well Sujith, I can already do that with user controls, why shall I learn another framework?  That’s correct, you can decouple using user controls, but you still have to manage some amount of coupling, like how to do you communicate between the controls, how do you subscribe/unsubscribe, loading/unloading views dynamically. Prism is not a replacement for user controls, provides the following features which greatly help in designing the composite applications. Dependency Injection (DI)/ Inversion of Control (IoC) Modules Regions Event Aggregator  Commands Simply put, MVVM helps building a single view and Prism helps building an application using the views There are other open source alternatives to Prism, like MVVMLight, Cinch, take a look at them as well. Lets dig into the source code.  1. Solution The solution is made of the following projects Framework: Holds the common functionality in building applications using WPF and Prism TaxiClient: Start up project, boot strapping and app styling TaxiCommon: Helps with the business logic TaxiModules: Holds the meat of the application with views and view models TaxiTests: To test the application 2. DI / IoC Dependency Injection (DI) as the name implies refers to injecting dependencies and Inversion of Control (IoC) means the calling code has no direct control on the dependencies, opposite of normal way of programming where dependencies are passed by caller, i.e inversion; aside from some differences in terminology the concept is same in both the cases. The idea behind DI/IoC pattern is to reduce the amount of direct coupling between different components of the application, the higher the dependency the more tightly coupled the application resulting in code which is hard to modify, unit test and mock.  Initializing Dependency Injection through BootStrapper TaxiClient is the starting project of the solution and App (App.xaml)  is the starting class that gets called when you run the application. From the App’s OnStartup method we will invoke BootStrapper.   namespace TaxiClient { /// <summary> /// Interaction logic for App.xaml /// </summary> public partial class App : Application { protected override void OnStartup(StartupEventArgs e) { base.OnStartup(e);   (new BootStrapper()).Run(); } } } BootStrapper is your contact point for initializing the application including dependency injection, creating Shell and other frameworks. We are going to use Unity for DI and there are lot of open source DI frameworks like Spring.Net, StructureMap etc with different feature set  and you can choose a framework based on your preferences. Note that Prism comes with in built support for Unity, for example we are deriving from UnityBootStrapper in our case and for any other DI framework you have to extend the Prism appropriately   namespace TaxiClient { public class BootStrapper: UnityBootstrapper { protected override IModuleCatalog CreateModuleCatalog() { return new ConfigurationModuleCatalog(); } protected override DependencyObject CreateShell() { Framework.FrameworkBootStrapper.Run(Container, Application.Current.Dispatcher);   Shell shell = new Shell(); shell.ResizeMode = ResizeMode.NoResize; shell.Show();   return shell; } } } Lets take a look into  FrameworkBootStrapper to check out how to register with unity container. namespace Framework { public class FrameworkBootStrapper { public static void Run(IUnityContainer container, Dispatcher dispatcher) { UIDispatcher uiDispatcher = new UIDispatcher(dispatcher); container.RegisterInstance<IDispatcherService>(uiDispatcher);   container.RegisterType<IInjectSingleViewService, InjectSingleViewService>( new ContainerControlledLifetimeManager());   . . . } } } In the above code we are registering two components with unity container. You shall observe that we are following two different approaches, RegisterInstance and RegisterType.  With RegisterInstance we are registering an existing instance and the same instance will be returned for every request made for IDispatcherService   and with RegisterType we are requesting unity container to create an instance for us when required, i.e., when I request for an instance for IInjectSingleViewService, unity will create/return an instance of InjectSingleViewService class and with RegisterType we can configure the life time of the instance being created. With ContaienrControllerLifetimeManager, the unity container caches the instance and reuses for any subsequent requests, without recreating a new instance. Lets take a look into FareViewModel.cs and it’s constructor. The constructor takes one parameter IEventAggregator and if you try to find all references in your solution for IEventAggregator, you will not find a single location where an instance of EventAggregator is passed directly to the constructor. The compiler still finds an instance and works fine because Prism is already configured when used with Unity container to return an instance of EventAggregator when requested for IEventAggregator and in this particular case it is called constructor injection. public class FareViewModel:ObservableBase, IDataErrorInfo { ... private IEventAggregator _eventAggregator;   public FareViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator; InitializePropertyNames(); InitializeModel(); PropertyChanged += OnPropertyChanged; } ... 3. Shell Shells are very similar in operation to Master Pages in asp.net or MDI in Windows Forms. And shells contain regions which display the views, you can have as many regions as you wish in a given view. You can also nest regions. i.e, one region can load a view which in itself may contain other regions. We have to create a shell at the start of the application and are doing it by overriding CreateShell method from BootStrapper From the following Shell.xaml you shall notice that we have two content controls with Region names as ‘MenuRegion’ and ‘MainRegion’.  The idea here is that you can inject any user controls into the regions dynamically, i.e., a Menu User Control for MenuRegion and based on the user action you can load appropriate view into MainRegion.    <Window x:Class="TaxiClient.Shell" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Regions="clr-namespace:Microsoft.Practices.Prism.Regions;assembly=Microsoft.Practices.Prism" Title="Taxi" Height="370" Width="800"> <Grid Margin="2"> <ContentControl Regions:RegionManager.RegionName="MenuRegion" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" />   <ContentControl Grid.Row="1" Regions:RegionManager.RegionName="MainRegion" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" /> <!--<Border Grid.ColumnSpan="2" BorderThickness="2" CornerRadius="3" BorderBrush="LightBlue" />-->   </Grid> </Window> 4. Modules Prism provides the ability to build composite applications and modules play an important role in it. For example if you are building a Mortgage Loan Processor application with 3 components, i.e. customer’s credit history,  existing mortgages, new home/loan information; and consider that the customer’s credit history component involves gathering data about his/her address, background information, job details etc. The idea here using Prism modules is to separate the implementation of these 3 components into their own visual studio projects allowing to build components with no dependency on each other and independently. If we need to add another component to the application, the component can be developed by in house team or some other team in the organization by starting with a new Visual Studio project and adding to the solution at the run time with very little knowledge about the application. Prism modules are defined by implementing the IModule interface and each visual studio project to be considered as a module should implement the IModule interface.  From the BootStrapper.cs you shall observe that we are overriding the method by returning a ConfiguratingModuleCatalog which returns the modules that are registered for the application using the app.config file  and you can also add module using code. Lets take a look into configuration file.   <?xml version="1.0"?> <configuration> <configSections> <section name="modules" type="Microsoft.Practices.Prism.Modularity.ModulesConfigurationSection, Microsoft.Practices.Prism"/> </configSections> <modules> <module assemblyFile="TaxiModules.dll" moduleType="TaxiModules.ModuleInitializer, TaxiModules" moduleName="TaxiModules"/> </modules> </configuration> Here we are adding TaxiModules project to our solution and TaxiModules.ModuleInitializer implements IModule interface   5. Module Mapper With Prism modules you can dynamically add or remove modules from the regions, apart from that Prism also provides API to control adding/removing the views from a region within the same module. Taxi Information Screen: Engage the Taxi Screen: The sample application has two screens, ‘Taxi Information’ and ‘Engage the Taxi’ and they both reside in same module, TaxiModules. ‘Engage the Taxi’ is again made of two user controls, FareView on the left and TotalView on the right. We have created a Shell with two regions, MenuRegion and MainRegion with menu loaded into MenuRegion. We can create a wrapper user control called EngageTheTaxi made of FareView and TotalView and load either TaxiInfo or EngageTheTaxi into MainRegion based on the user action. Though it will work it tightly binds the user controls and for every combination of user controls, we need to create a dummy wrapper control to contain them. Instead we can apply the principles we learned so far from Shell/regions and introduce another template (LeftAndRightRegionView.xaml) made of two regions Region1 (left) and Region2 (right) and load  FareView and TotalView dynamically.  To help with loading of the views dynamically I have introduce an helper an interface, IInjectSingleViewService,  idea suggested by Mike Taulty, a must read blog for .Net developers. using System; using System.Collections.Generic; using System.ComponentModel;   namespace Framework.PresentationUtility.Navigation {   public interface IInjectSingleViewService : INotifyPropertyChanged { IEnumerable<CommandViewDefinition> Commands { get; } IEnumerable<ModuleViewDefinition> Modules { get; }   void RegisterViewForRegion(string commandName, string viewName, string regionName, Type viewType); void ClearViewFromRegion(string viewName, string regionName); void RegisterModule(string moduleName, IList<ModuleMapper> moduleMappers); } } The Interface declares three methods to work with views: RegisterViewForRegion: Registers a view with a particular region. You can register multiple views and their regions under one command.  When this particular command is invoked all the views registered under it will be loaded into their regions. ClearViewFromRegion: To unload a specific view from a region. RegisterModule: The idea is when a command is invoked you can load the UI with set of controls in their default position and based on the user interaction, you can load different contols in to different regions on the fly.  And it is supported ModuleViewDefinition and ModuleMappers as shown below. namespace Framework.PresentationUtility.Navigation { public class ModuleViewDefinition { public string ModuleName { get; set; } public IList<ModuleMapper> ModuleMappers; public ICommand Command { get; set; } }   public class ModuleMapper { public string ViewName { get; set; } public string RegionName { get; set; } public Type ViewType { get; set; } } } 6. Event Aggregator Prism event aggregator enables messaging between components as in Observable pattern, Notifier notifies the Observer which receives notification it is interested in. When it comes to Observable pattern, Observer has to unsubscribes for notifications when it no longer interested in notifications, which allows the Notifier to remove the Observer’s reference from it’s local cache. Though .Net has managed garbage collection it cannot remove inactive the instances referenced by an active instance resulting in memory leak, keeping the Observers in memory as long as Notifier stays in memory.  Developers have to be very careful to unsubscribe when necessary and it often gets overlooked, to overcome these problems Prism Event Aggregator uses weak references to cache the reference (Observer in this case)  and releases the reference (memory) once the instance goes out of scope. Using event aggregator is very simple, declare a generic type of CompositePresenationEvent by inheriting from it. using Microsoft.Practices.Prism.Events; using TaxiCommon.BAO;   namespace TaxiCommon.CompositeEvents { public class TaxiOnMoveEvent:CompositePresentationEvent<TaxiOnMove> { } }   TaxiOnMove.cs includes the properties which we want to exchange between the parties, FareView and TotalView. using System;   namespace TaxiCommon.BAO { public class TaxiOnMove { public TimeSpan MinutesAtTweleveMPH { get; set; } public double MilesAtSixMPH { get; set; } } }   Lets take a look into FareViewodel (Notifier) and how it raises the event.  Here we are raising the event by getting the event through GetEvent<..>() and publishing it with the payload private void OnAddMinutes(object obj) { TaxiOnMove payload = new TaxiOnMove(); if(MilesAtSixMPH != null) payload.MilesAtSixMPH = MilesAtSixMPH.Value; if(MinutesAtTweleveMPH != null) payload.MinutesAtTweleveMPH = new TimeSpan(0,0,MinutesAtTweleveMPH.Value,0);   _eventAggregator.GetEvent<TaxiOnMoveEvent>().Publish(payload); ResetMinutesAndMiles(); } And TotalViewModel(Observer) subscribes to notifications by getting the event through GetEvent<..>() namespace TaxiModules.ViewModels { public class TotalViewModel:ObservableBase { .... private IEventAggregator _eventAggregator;   public TotalViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator; ... }   private void SubscribeToEvents() { _eventAggregator.GetEvent<TaxiStartedEvent>() .Subscribe(OnTaxiStarted, ThreadOption.UIThread,false,(filter) => true); _eventAggregator.GetEvent<TaxiOnMoveEvent>() .Subscribe(OnTaxiMove, ThreadOption.UIThread, false, (filter) => true); _eventAggregator.GetEvent<TaxiResetEvent>() .Subscribe(OnTaxiReset, ThreadOption.UIThread, false, (filter) => true); }   ... private void OnTaxiMove(TaxiOnMove taxiOnMove) { OnMoveFare fare = new OnMoveFare(taxiOnMove); Fares.Add(fare); SetTotalFare(new []{fare}); }   .... 7. MVVM through example In this section we are going to look into MVVM implementation through example.  I have all the modules declared in a single project, TaxiModules, again it is not necessary to have them into one project. Once the user logs into the application, will be greeted with the ‘Engage the Taxi’ screen which is made of two user controls, FareView.xaml and TotalView.Xaml. As you can see from the solution explorer, each of them have their own code behind files and  ViewModel classes, FareViewMode.cs, TotalViewModel.cs Lets take a look in to the FareView and how it interacts with FareViewModel using MVVM implementation. FareView.xaml acts as a view and FareViewMode.cs is it’s view model. The FareView code behind class   namespace TaxiModules.Views { /// <summary> /// Interaction logic for FareView.xaml /// </summary> public partial class FareView : UserControl { public FareView(FareViewModel viewModel) { InitializeComponent(); this.Loaded += (s, e) => { this.DataContext = viewModel; }; } } } The FareView is bound to FareViewModel through the data context  and you shall observe that DataContext is of type Object, i.e. the FareView doesn’t really know the type of ViewModel (FareViewModel). This helps separation of View and ViewModel as View and ViewModel are independent of each other, you can bind FareView to FareViewModel2 as well and the application compiles just fine. Lets take a look into FareView xaml file  <UserControl x:Class="TaxiModules.Views.FareView" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Toolkit="clr-namespace:Microsoft.Windows.Controls;assembly=WPFToolkit" xmlns:Commands="clr-namespace:Microsoft.Practices.Prism.Commands;assembly=Microsoft.Practices.Prism"> <Grid Margin="10" > ....   <Border Style="{DynamicResource innerBorder}" Grid.Row="0" Grid.Column="0" Grid.RowSpan="11" Grid.ColumnSpan="2" Panel.ZIndex="1"/>   <Label Grid.Row="0" Content="Engage the Taxi" Style="{DynamicResource innerHeader}"/> <Label Grid.Row="1" Content="Select the State"/> <ComboBox Grid.Row="1" Grid.Column="1" ItemsSource="{Binding States}" Height="auto"> <ComboBox.ItemTemplate> <DataTemplate> <TextBlock Text="{Binding Name}"/> </DataTemplate> </ComboBox.ItemTemplate> <ComboBox.SelectedItem> <Binding Path="SelectedState" Mode="TwoWay"/> </ComboBox.SelectedItem> </ComboBox> <Label Grid.Row="2" Content="Select the Date of Entry"/> <Toolkit:DatePicker Grid.Row="2" Grid.Column="1" SelectedDate="{Binding DateOfEntry, ValidatesOnDataErrors=true}" /> <Label Grid.Row="3" Content="Enter time 24hr format"/> <TextBox Grid.Row="3" Grid.Column="1" Text="{Binding TimeOfEntry, TargetNullValue=''}"/> <Button Grid.Row="4" Grid.Column="1" Content="Start the Meter" Commands:Click.Command="{Binding StartMeterCommand}" />   <Label Grid.Row="5" Content="Run the Taxi" Style="{DynamicResource innerHeader}"/> <Label Grid.Row="6" Content="Number of Miles &lt;@6mph"/> <TextBox Grid.Row="6" Grid.Column="1" Text="{Binding MilesAtSixMPH, TargetNullValue='', ValidatesOnDataErrors=true}"/> <Label Grid.Row="7" Content="Number of Minutes @12mph"/> <TextBox Grid.Row="7" Grid.Column="1" Text="{Binding MinutesAtTweleveMPH, TargetNullValue=''}"/> <Button Grid.Row="8" Grid.Column="1" Content="Add Minutes and Miles " Commands:Click.Command="{Binding AddMinutesCommand}"/> <Label Grid.Row="9" Content="Other Operations" Style="{DynamicResource innerHeader}"/> <Button Grid.Row="10" Grid.Column="1" Content="Reset the Meter" Commands:Click.Command="{Binding ResetCommand}"/>   </Grid> </UserControl> The highlighted code from the above code shows data binding, for example ComboBox which displays list of states has it’s ItemsSource bound to States property, with DataTemplate bound to Name and SelectedItem  to SelectedState. You might be wondering what are all these properties and how it is able to bind to them.  The answer lies in data context, i.e., when you bound a control, WPF looks for data context on the root object (Grid in this case) and if it can’t find data context it will look into root’s root, i.e. FareView UserControl and it is bound to FareViewModel.  Each of those properties have be declared on the ViewModel for the View to bind correctly. To put simply, View is bound to ViewModel through data context of type object and every control that is bound on the View actually binds to the public property on the ViewModel. Lets look into the ViewModel code (the following code is not an exact copy of FareViewMode.cs, pasted relevant code for this section)   namespace TaxiModules.ViewModels { public class FareViewModel:ObservableBase, IDataErrorInfo { public List<USState> States { get { return USStates.StateList; } }   public USState SelectedState { get { return _selectedState; } set { _selectedState = value; RaisePropertyChanged(_selectedStatePropertyName); } }   public DateTime? DateOfEntry { get { return _dateOfEntry; } set { _dateOfEntry = value; RaisePropertyChanged(_dateOfEntryPropertyName); } }   public TimeSpan? TimeOfEntry { get { return _timeOfEntry; } set { _timeOfEntry = value; RaisePropertyChanged(_timeOfEntryPropertyName); } }   public double? MilesAtSixMPH { get { return _milesAtSixMPH; } set { _milesAtSixMPH = value; RaisePropertyChanged(_distanceAtSixMPHPropertyName); } }   public int? MinutesAtTweleveMPH { get { return _minutesAtTweleveMPH; } set { _minutesAtTweleveMPH = value; RaisePropertyChanged(_minutesAtTweleveMPHPropertyName); } }   public ICommand StartMeterCommand { get { if(_startMeterCommand == null) { _startMeterCommand = new DelegateCommand<object>(OnStartMeter, CanStartMeter); } return _startMeterCommand; } }   public ICommand AddMinutesCommand { get { if(_addMinutesCommand == null) { _addMinutesCommand = new DelegateCommand<object>(OnAddMinutes, CanAddMinutes); } return _addMinutesCommand; } }   public ICommand ResetCommand { get { if(_resetCommand == null) { _resetCommand = new DelegateCommand<object>(OnResetCommand); } return _resetCommand; } }   } private void OnStartMeter(object obj) { _eventAggregator.GetEvent<TaxiStartedEvent>().Publish( new TaxiStarted() { EngagedOn = DateOfEntry.Value.Date + TimeOfEntry.Value, EngagedState = SelectedState.Value });   _isMeterStarted = true; OnPropertyChanged(this,null); } And views communicate user actions like button clicks, tree view item selections, etc using commands. When user clicks on ‘Start the Meter’ button it invokes the method StartMeterCommand, which calls the method OnStartMeter which publishes the event to TotalViewModel using event aggregator  and TaxiStartedEvent. namespace TaxiModules.ViewModels { public class TotalViewModel:ObservableBase { ... private IEventAggregator _eventAggregator;   public TotalViewModel(IEventAggregator eventAggregator) { _eventAggregator = eventAggregator;   InitializePropertyNames(); InitializeModel(); SubscribeToEvents(); }   public decimal? TotalFare { get { return _totalFare; } set { _totalFare = value; RaisePropertyChanged(_totalFarePropertyName); } } .... private void SubscribeToEvents() { _eventAggregator.GetEvent<TaxiStartedEvent>().Subscribe(OnTaxiStarted, ThreadOption.UIThread,false,(filter) => true); _eventAggregator.GetEvent<TaxiOnMoveEvent>().Subscribe(OnTaxiMove, ThreadOption.UIThread, false, (filter) => true); _eventAggregator.GetEvent<TaxiResetEvent>().Subscribe(OnTaxiReset, ThreadOption.UIThread, false, (filter) => true); }   private void OnTaxiStarted(TaxiStarted taxiStarted) { Fares.Add(new EntryFare()); Fares.Add(new StateTaxFare(taxiStarted)); Fares.Add(new NightSurchargeFare(taxiStarted)); Fares.Add(new PeakHourWeekdayFare(taxiStarted));   SetTotalFare(Fares); }   private void SetTotalFare(IEnumerable<IFare> fares) { TotalFare = (_totalFare ?? 0) + TaxiFareHelper.GetTotalFare(fares); } ....   } }   TotalViewModel subscribes to events, TaxiStartedEvent and rest. When TaxiStartedEvent gets invoked it calls the OnTaxiStarted method which sets the total fare which includes entry fee, state tax, nightly surcharge, peak hour weekday fare.   Note that TotalViewModel derives from ObservableBase which implements the method RaisePropertyChanged which we are invoking in Set of TotalFare property, i.e, once we update the TotalFare property it raises an the event that  allows the TotalFare text box to fetch the new value through the data context. ViewModel is communicating with View through data context and it has no knowledge about View, helping in loose coupling of ViewModel and View.   I have attached the source code (.Net 4.0, Prism 4.0, VS 2010) , download and play with it and don’t forget to leave your comments.  

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  • New features of C# 4.0

    This article covers New features of C# 4.0. Article has been divided into below sections. Introduction. Dynamic Lookup. Named and Optional Arguments. Features for COM interop. Variance. Relationship with Visual Basic. Resources. Other interested readings… 22 New Features of Visual Studio 2008 for .NET Professionals 50 New Features of SQL Server 2008 IIS 7.0 New features Introduction It is now close to a year since Microsoft Visual C# 3.0 shipped as part of Visual Studio 2008. In the VS Managed Languages team we are hard at work on creating the next version of the language (with the unsurprising working title of C# 4.0), and this document is a first public description of the planned language features as we currently see them. Please be advised that all this is in early stages of production and is subject to change. Part of the reason for sharing our plans in public so early is precisely to get the kind of feedback that will cause us to improve the final product before it rolls out. Simultaneously with the publication of this whitepaper, a first public CTP (community technology preview) of Visual Studio 2010 is going out as a Virtual PC image for everyone to try. Please use it to play and experiment with the features, and let us know of any thoughts you have. We ask for your understanding and patience working with very early bits, where especially new or newly implemented features do not have the quality or stability of a final product. The aim of the CTP is not to give you a productive work environment but to give you the best possible impression of what we are working on for the next release. The CTP contains a number of walkthroughs, some of which highlight the new language features of C# 4.0. Those are excellent for getting a hands-on guided tour through the details of some common scenarios for the features. You may consider this whitepaper a companion document to these walkthroughs, complementing them with a focus on the overall language features and how they work, as opposed to the specifics of the concrete scenarios. C# 4.0 The major theme for C# 4.0 is dynamic programming. Increasingly, objects are “dynamic” in the sense that their structure and behavior is not captured by a static type, or at least not one that the compiler knows about when compiling your program. Some examples include a. objects from dynamic programming languages, such as Python or Ruby b. COM objects accessed through IDispatch c. ordinary .NET types accessed through reflection d. objects with changing structure, such as HTML DOM objects While C# remains a statically typed language, we aim to vastly improve the interaction with such objects. A secondary theme is co-evolution with Visual Basic. Going forward we will aim to maintain the individual character of each language, but at the same time important new features should be introduced in both languages at the same time. They should be differentiated more by style and feel than by feature set. The new features in C# 4.0 fall into four groups: Dynamic lookup Dynamic lookup allows you to write method, operator and indexer calls, property and field accesses, and even object invocations which bypass the C# static type checking and instead gets resolved at runtime. Named and optional parameters Parameters in C# can now be specified as optional by providing a default value for them in a member declaration. When the member is invoked, optional arguments can be omitted. Furthermore, any argument can be passed by parameter name instead of position. COM specific interop features Dynamic lookup as well as named and optional parameters both help making programming against COM less painful than today. On top of that, however, we are adding a number of other small features that further improve the interop experience. Variance It used to be that an IEnumerable<string> wasn’t an IEnumerable<object>. Now it is – C# embraces type safe “co-and contravariance” and common BCL types are updated to take advantage of that. Dynamic Lookup Dynamic lookup allows you a unified approach to invoking things dynamically. With dynamic lookup, when you have an object in your hand you do not need to worry about whether it comes from COM, IronPython, the HTML DOM or reflection; you just apply operations to it and leave it to the runtime to figure out what exactly those operations mean for that particular object. This affords you enormous flexibility, and can greatly simplify your code, but it does come with a significant drawback: Static typing is not maintained for these operations. A dynamic object is assumed at compile time to support any operation, and only at runtime will you get an error if it wasn’t so. Oftentimes this will be no loss, because the object wouldn’t have a static type anyway, in other cases it is a tradeoff between brevity and safety. In order to facilitate this tradeoff, it is a design goal of C# to allow you to opt in or opt out of dynamic behavior on every single call. The dynamic type C# 4.0 introduces a new static type called dynamic. When you have an object of type dynamic you can “do things to it” that are resolved only at runtime: dynamic d = GetDynamicObject(…); d.M(7); The C# compiler allows you to call a method with any name and any arguments on d because it is of type dynamic. At runtime the actual object that d refers to will be examined to determine what it means to “call M with an int” on it. The type dynamic can be thought of as a special version of the type object, which signals that the object can be used dynamically. It is easy to opt in or out of dynamic behavior: any object can be implicitly converted to dynamic, “suspending belief” until runtime. Conversely, there is an “assignment conversion” from dynamic to any other type, which allows implicit conversion in assignment-like constructs: dynamic d = 7; // implicit conversion int i = d; // assignment conversion Dynamic operations Not only method calls, but also field and property accesses, indexer and operator calls and even delegate invocations can be dispatched dynamically: dynamic d = GetDynamicObject(…); d.M(7); // calling methods d.f = d.P; // getting and settings fields and properties d[“one”] = d[“two”]; // getting and setting thorugh indexers int i = d + 3; // calling operators string s = d(5,7); // invoking as a delegate The role of the C# compiler here is simply to package up the necessary information about “what is being done to d”, so that the runtime can pick it up and determine what the exact meaning of it is given an actual object d. Think of it as deferring part of the compiler’s job to runtime. The result of any dynamic operation is itself of type dynamic. Runtime lookup At runtime a dynamic operation is dispatched according to the nature of its target object d: COM objects If d is a COM object, the operation is dispatched dynamically through COM IDispatch. This allows calling to COM types that don’t have a Primary Interop Assembly (PIA), and relying on COM features that don’t have a counterpart in C#, such as indexed properties and default properties. Dynamic objects If d implements the interface IDynamicObject d itself is asked to perform the operation. Thus by implementing IDynamicObject a type can completely redefine the meaning of dynamic operations. This is used intensively by dynamic languages such as IronPython and IronRuby to implement their own dynamic object models. It will also be used by APIs, e.g. by the HTML DOM to allow direct access to the object’s properties using property syntax. Plain objects Otherwise d is a standard .NET object, and the operation will be dispatched using reflection on its type and a C# “runtime binder” which implements C#’s lookup and overload resolution semantics at runtime. This is essentially a part of the C# compiler running as a runtime component to “finish the work” on dynamic operations that was deferred by the static compiler. Example Assume the following code: dynamic d1 = new Foo(); dynamic d2 = new Bar(); string s; d1.M(s, d2, 3, null); Because the receiver of the call to M is dynamic, the C# compiler does not try to resolve the meaning of the call. Instead it stashes away information for the runtime about the call. This information (often referred to as the “payload”) is essentially equivalent to: “Perform an instance method call of M with the following arguments: 1. a string 2. a dynamic 3. a literal int 3 4. a literal object null” At runtime, assume that the actual type Foo of d1 is not a COM type and does not implement IDynamicObject. In this case the C# runtime binder picks up to finish the overload resolution job based on runtime type information, proceeding as follows: 1. Reflection is used to obtain the actual runtime types of the two objects, d1 and d2, that did not have a static type (or rather had the static type dynamic). The result is Foo for d1 and Bar for d2. 2. Method lookup and overload resolution is performed on the type Foo with the call M(string,Bar,3,null) using ordinary C# semantics. 3. If the method is found it is invoked; otherwise a runtime exception is thrown. Overload resolution with dynamic arguments Even if the receiver of a method call is of a static type, overload resolution can still happen at runtime. This can happen if one or more of the arguments have the type dynamic: Foo foo = new Foo(); dynamic d = new Bar(); var result = foo.M(d); The C# runtime binder will choose between the statically known overloads of M on Foo, based on the runtime type of d, namely Bar. The result is again of type dynamic. The Dynamic Language Runtime An important component in the underlying implementation of dynamic lookup is the Dynamic Language Runtime (DLR), which is a new API in .NET 4.0. The DLR provides most of the infrastructure behind not only C# dynamic lookup but also the implementation of several dynamic programming languages on .NET, such as IronPython and IronRuby. Through this common infrastructure a high degree of interoperability is ensured, but just as importantly the DLR provides excellent caching mechanisms which serve to greatly enhance the efficiency of runtime dispatch. To the user of dynamic lookup in C#, the DLR is invisible except for the improved efficiency. However, if you want to implement your own dynamically dispatched objects, the IDynamicObject interface allows you to interoperate with the DLR and plug in your own behavior. This is a rather advanced task, which requires you to understand a good deal more about the inner workings of the DLR. For API writers, however, it can definitely be worth the trouble in order to vastly improve the usability of e.g. a library representing an inherently dynamic domain. Open issues There are a few limitations and things that might work differently than you would expect. · The DLR allows objects to be created from objects that represent classes. However, the current implementation of C# doesn’t have syntax to support this. · Dynamic lookup will not be able to find extension methods. Whether extension methods apply or not depends on the static context of the call (i.e. which using clauses occur), and this context information is not currently kept as part of the payload. · Anonymous functions (i.e. lambda expressions) cannot appear as arguments to a dynamic method call. The compiler cannot bind (i.e. “understand”) an anonymous function without knowing what type it is converted to. One consequence of these limitations is that you cannot easily use LINQ queries over dynamic objects: dynamic collection = …; var result = collection.Select(e => e + 5); If the Select method is an extension method, dynamic lookup will not find it. Even if it is an instance method, the above does not compile, because a lambda expression cannot be passed as an argument to a dynamic operation. There are no plans to address these limitations in C# 4.0. Named and Optional Arguments Named and optional parameters are really two distinct features, but are often useful together. Optional parameters allow you to omit arguments to member invocations, whereas named arguments is a way to provide an argument using the name of the corresponding parameter instead of relying on its position in the parameter list. Some APIs, most notably COM interfaces such as the Office automation APIs, are written specifically with named and optional parameters in mind. Up until now it has been very painful to call into these APIs from C#, with sometimes as many as thirty arguments having to be explicitly passed, most of which have reasonable default values and could be omitted. Even in APIs for .NET however you sometimes find yourself compelled to write many overloads of a method with different combinations of parameters, in order to provide maximum usability to the callers. Optional parameters are a useful alternative for these situations. Optional parameters A parameter is declared optional simply by providing a default value for it: public void M(int x, int y = 5, int z = 7); Here y and z are optional parameters and can be omitted in calls: M(1, 2, 3); // ordinary call of M M(1, 2); // omitting z – equivalent to M(1, 2, 7) M(1); // omitting both y and z – equivalent to M(1, 5, 7) Named and optional arguments C# 4.0 does not permit you to omit arguments between commas as in M(1,,3). This could lead to highly unreadable comma-counting code. Instead any argument can be passed by name. Thus if you want to omit only y from a call of M you can write: M(1, z: 3); // passing z by name or M(x: 1, z: 3); // passing both x and z by name or even M(z: 3, x: 1); // reversing the order of arguments All forms are equivalent, except that arguments are always evaluated in the order they appear, so in the last example the 3 is evaluated before the 1. Optional and named arguments can be used not only with methods but also with indexers and constructors. Overload resolution Named and optional arguments affect overload resolution, but the changes are relatively simple: A signature is applicable if all its parameters are either optional or have exactly one corresponding argument (by name or position) in the call which is convertible to the parameter type. Betterness rules on conversions are only applied for arguments that are explicitly given – omitted optional arguments are ignored for betterness purposes. If two signatures are equally good, one that does not omit optional parameters is preferred. M(string s, int i = 1); M(object o); M(int i, string s = “Hello”); M(int i); M(5); Given these overloads, we can see the working of the rules above. M(string,int) is not applicable because 5 doesn’t convert to string. M(int,string) is applicable because its second parameter is optional, and so, obviously are M(object) and M(int). M(int,string) and M(int) are both better than M(object) because the conversion from 5 to int is better than the conversion from 5 to object. Finally M(int) is better than M(int,string) because no optional arguments are omitted. Thus the method that gets called is M(int). Features for COM interop Dynamic lookup as well as named and optional parameters greatly improve the experience of interoperating with COM APIs such as the Office Automation APIs. In order to remove even more of the speed bumps, a couple of small COM-specific features are also added to C# 4.0. Dynamic import Many COM methods accept and return variant types, which are represented in the PIAs as object. In the vast majority of cases, a programmer calling these methods already knows the static type of a returned object from context, but explicitly has to perform a cast on the returned value to make use of that knowledge. These casts are so common that they constitute a major nuisance. In order to facilitate a smoother experience, you can now choose to import these COM APIs in such a way that variants are instead represented using the type dynamic. In other words, from your point of view, COM signatures now have occurrences of dynamic instead of object in them. This means that you can easily access members directly off a returned object, or you can assign it to a strongly typed local variable without having to cast. To illustrate, you can now say excel.Cells[1, 1].Value = "Hello"; instead of ((Excel.Range)excel.Cells[1, 1]).Value2 = "Hello"; and Excel.Range range = excel.Cells[1, 1]; instead of Excel.Range range = (Excel.Range)excel.Cells[1, 1]; Compiling without PIAs Primary Interop Assemblies are large .NET assemblies generated from COM interfaces to facilitate strongly typed interoperability. They provide great support at design time, where your experience of the interop is as good as if the types where really defined in .NET. However, at runtime these large assemblies can easily bloat your program, and also cause versioning issues because they are distributed independently of your application. The no-PIA feature allows you to continue to use PIAs at design time without having them around at runtime. Instead, the C# compiler will bake the small part of the PIA that a program actually uses directly into its assembly. At runtime the PIA does not have to be loaded. Omitting ref Because of a different programming model, many COM APIs contain a lot of reference parameters. Contrary to refs in C#, these are typically not meant to mutate a passed-in argument for the subsequent benefit of the caller, but are simply another way of passing value parameters. It therefore seems unreasonable that a C# programmer should have to create temporary variables for all such ref parameters and pass these by reference. Instead, specifically for COM methods, the C# compiler will allow you to pass arguments by value to such a method, and will automatically generate temporary variables to hold the passed-in values, subsequently discarding these when the call returns. In this way the caller sees value semantics, and will not experience any side effects, but the called method still gets a reference. Open issues A few COM interface features still are not surfaced in C#. Most notably these include indexed properties and default properties. As mentioned above these will be respected if you access COM dynamically, but statically typed C# code will still not recognize them. There are currently no plans to address these remaining speed bumps in C# 4.0. Variance An aspect of generics that often comes across as surprising is that the following is illegal: IList<string> strings = new List<string>(); IList<object> objects = strings; The second assignment is disallowed because strings does not have the same element type as objects. There is a perfectly good reason for this. If it were allowed you could write: objects[0] = 5; string s = strings[0]; Allowing an int to be inserted into a list of strings and subsequently extracted as a string. This would be a breach of type safety. However, there are certain interfaces where the above cannot occur, notably where there is no way to insert an object into the collection. Such an interface is IEnumerable<T>. If instead you say: IEnumerable<object> objects = strings; There is no way we can put the wrong kind of thing into strings through objects, because objects doesn’t have a method that takes an element in. Variance is about allowing assignments such as this in cases where it is safe. The result is that a lot of situations that were previously surprising now just work. Covariance In .NET 4.0 the IEnumerable<T> interface will be declared in the following way: public interface IEnumerable<out T> : IEnumerable { IEnumerator<T> GetEnumerator(); } public interface IEnumerator<out T> : IEnumerator { bool MoveNext(); T Current { get; } } The “out” in these declarations signifies that the T can only occur in output position in the interface – the compiler will complain otherwise. In return for this restriction, the interface becomes “covariant” in T, which means that an IEnumerable<A> is considered an IEnumerable<B> if A has a reference conversion to B. As a result, any sequence of strings is also e.g. a sequence of objects. This is useful e.g. in many LINQ methods. Using the declarations above: var result = strings.Union(objects); // succeeds with an IEnumerable<object> This would previously have been disallowed, and you would have had to to some cumbersome wrapping to get the two sequences to have the same element type. Contravariance Type parameters can also have an “in” modifier, restricting them to occur only in input positions. An example is IComparer<T>: public interface IComparer<in T> { public int Compare(T left, T right); } The somewhat baffling result is that an IComparer<object> can in fact be considered an IComparer<string>! It makes sense when you think about it: If a comparer can compare any two objects, it can certainly also compare two strings. This property is referred to as contravariance. A generic type can have both in and out modifiers on its type parameters, as is the case with the Func<…> delegate types: public delegate TResult Func<in TArg, out TResult>(TArg arg); Obviously the argument only ever comes in, and the result only ever comes out. Therefore a Func<object,string> can in fact be used as a Func<string,object>. Limitations Variant type parameters can only be declared on interfaces and delegate types, due to a restriction in the CLR. Variance only applies when there is a reference conversion between the type arguments. For instance, an IEnumerable<int> is not an IEnumerable<object> because the conversion from int to object is a boxing conversion, not a reference conversion. Also please note that the CTP does not contain the new versions of the .NET types mentioned above. In order to experiment with variance you have to declare your own variant interfaces and delegate types. COM Example Here is a larger Office automation example that shows many of the new C# features in action. using System; using System.Diagnostics; using System.Linq; using Excel = Microsoft.Office.Interop.Excel; using Word = Microsoft.Office.Interop.Word; class Program { static void Main(string[] args) { var excel = new Excel.Application(); excel.Visible = true; excel.Workbooks.Add(); // optional arguments omitted excel.Cells[1, 1].Value = "Process Name"; // no casts; Value dynamically excel.Cells[1, 2].Value = "Memory Usage"; // accessed var processes = Process.GetProcesses() .OrderByDescending(p =&gt; p.WorkingSet) .Take(10); int i = 2; foreach (var p in processes) { excel.Cells[i, 1].Value = p.ProcessName; // no casts excel.Cells[i, 2].Value = p.WorkingSet; // no casts i++; } Excel.Range range = excel.Cells[1, 1]; // no casts Excel.Chart chart = excel.ActiveWorkbook.Charts. Add(After: excel.ActiveSheet); // named and optional arguments chart.ChartWizard( Source: range.CurrentRegion, Title: "Memory Usage in " + Environment.MachineName); //named+optional chart.ChartStyle = 45; chart.CopyPicture(Excel.XlPictureAppearance.xlScreen, Excel.XlCopyPictureFormat.xlBitmap, Excel.XlPictureAppearance.xlScreen); var word = new Word.Application(); word.Visible = true; word.Documents.Add(); // optional arguments word.Selection.Paste(); } } The code is much more terse and readable than the C# 3.0 counterpart. Note especially how the Value property is accessed dynamically. This is actually an indexed property, i.e. a property that takes an argument; something which C# does not understand. However the argument is optional. Since the access is dynamic, it goes through the runtime COM binder which knows to substitute the default value and call the indexed property. Thus, dynamic COM allows you to avoid accesses to the puzzling Value2 property of Excel ranges. Relationship with Visual Basic A number of the features introduced to C# 4.0 already exist or will be introduced in some form or other in Visual Basic: · Late binding in VB is similar in many ways to dynamic lookup in C#, and can be expected to make more use of the DLR in the future, leading to further parity with C#. · Named and optional arguments have been part of Visual Basic for a long time, and the C# version of the feature is explicitly engineered with maximal VB interoperability in mind. · NoPIA and variance are both being introduced to VB and C# at the same time. VB in turn is adding a number of features that have hitherto been a mainstay of C#. As a result future versions of C# and VB will have much better feature parity, for the benefit of everyone. Resources All available resources concerning C# 4.0 can be accessed through the C# Dev Center. Specifically, this white paper and other resources can be found at the Code Gallery site. Enjoy! span.fullpost {display:none;}

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  • Custom ASP.NET Routing to an HttpHandler

    - by Rick Strahl
    As of version 4.0 ASP.NET natively supports routing via the now built-in System.Web.Routing namespace. Routing features are automatically integrated into the HtttpRuntime via a few custom interfaces. New Web Forms Routing Support In ASP.NET 4.0 there are a host of improvements including routing support baked into Web Forms via a RouteData property available on the Page class and RouteCollection.MapPageRoute() route handler that makes it easy to route to Web forms. To map ASP.NET Page routes is as simple as setting up the routes with MapPageRoute:protected void Application_Start(object sender, EventArgs e) { RegisterRoutes(RouteTable.Routes); } void RegisterRoutes(RouteCollection routes) { routes.MapPageRoute("StockQuote", "StockQuote/{symbol}", "StockQuote.aspx"); routes.MapPageRoute("StockQuotes", "StockQuotes/{symbolList}", "StockQuotes.aspx"); } and then accessing the route data in the page you can then use the new Page class RouteData property to retrieve the dynamic route data information:public partial class StockQuote1 : System.Web.UI.Page { protected StockQuote Quote = null; protected void Page_Load(object sender, EventArgs e) { string symbol = RouteData.Values["symbol"] as string; StockServer server = new StockServer(); Quote = server.GetStockQuote(symbol); // display stock data in Page View } } Simple, quick and doesn’t require much explanation. If you’re using WebForms most of your routing needs should be served just fine by this simple mechanism. Kudos to the ASP.NET team for putting this in the box and making it easy! How Routing Works To handle Routing in ASP.NET involves these steps: Registering Routes Creating a custom RouteHandler to retrieve an HttpHandler Attaching RouteData to your HttpHandler Picking up Route Information in your Request code Registering routes makes ASP.NET aware of the Routes you want to handle via the static RouteTable.Routes collection. You basically add routes to this collection to let ASP.NET know which URL patterns it should watch for. You typically hook up routes off a RegisterRoutes method that fires in Application_Start as I did in the example above to ensure routes are added only once when the application first starts up. When you create a route, you pass in a RouteHandler instance which ASP.NET caches and reuses as routes are matched. Once registered ASP.NET monitors the routes and if a match is found just prior to the HttpHandler instantiation, ASP.NET uses the RouteHandler registered for the route and calls GetHandler() on it to retrieve an HttpHandler instance. The RouteHandler.GetHandler() method is responsible for creating an instance of an HttpHandler that is to handle the request and – if necessary – to assign any additional custom data to the handler. At minimum you probably want to pass the RouteData to the handler so the handler can identify the request based on the route data available. To do this you typically add  a RouteData property to your handler and then assign the property from the RouteHandlers request context. This is essentially how Page.RouteData comes into being and this approach should work well for any custom handler implementation that requires RouteData. It’s a shame that ASP.NET doesn’t have a top level intrinsic object that’s accessible off the HttpContext object to provide route data more generically, but since RouteData is directly tied to HttpHandlers and not all handlers support it it might cause some confusion of when it’s actually available. Bottom line is that if you want to hold on to RouteData you have to assign it to a custom property of the handler or else pass it to the handler via Context.Items[] object that can be retrieved on an as needed basis. It’s important to understand that routing is hooked up via RouteHandlers that are responsible for loading HttpHandler instances. RouteHandlers are invoked for every request that matches a route and through this RouteHandler instance the Handler gains access to the current RouteData. Because of this logic it’s important to understand that Routing is really tied to HttpHandlers and not available prior to handler instantiation, which is pretty late in the HttpRuntime’s request pipeline. IOW, Routing works with Handlers but not with earlier in the pipeline within Modules. Specifically ASP.NET calls RouteHandler.GetHandler() from the PostResolveRequestCache HttpRuntime pipeline event. Here’s the call stack at the beginning of the GetHandler() call: which fires just before handler resolution. Non-Page Routing – You need to build custom RouteHandlers If you need to route to a custom Http Handler or other non-Page (and non-MVC) endpoint in the HttpRuntime, there is no generic mapping support available. You need to create a custom RouteHandler that can manage creating an instance of an HttpHandler that is fired in response to a routed request. Depending on what you are doing this process can be simple or fairly involved as your code is responsible based on the route data provided which handler to instantiate, and more importantly how to pass the route data on to the Handler. Luckily creating a RouteHandler is easy by implementing the IRouteHandler interface which has only a single GetHttpHandler(RequestContext context) method. In this method you can pick up the requestContext.RouteData, instantiate the HttpHandler of choice, and assign the RouteData to it. Then pass back the handler and you’re done.Here’s a simple example of GetHttpHandler() method that dynamically creates a handler based on a passed in Handler type./// <summary> /// Retrieves an Http Handler based on the type specified in the constructor /// </summary> /// <param name="requestContext"></param> /// <returns></returns> IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; // If we're dealing with a Callback Handler // pass the RouteData for this route to the Handler if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; } Note that this code checks for a specific type of handler and if it matches assigns the RouteData to this handler. This is optional but quite a common scenario if you want to work with RouteData. If the handler you need to instantiate isn’t under your control but you still need to pass RouteData to Handler code, an alternative is to pass the RouteData via the HttpContext.Items collection:IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; requestContext.HttpContext.Items["RouteData"] = requestContext.RouteData; return handler; } The code in the handler implementation can then pick up the RouteData from the context collection as needed:RouteData routeData = HttpContext.Current.Items["RouteData"] as RouteData This isn’t as clean as having an explicit RouteData property, but it does have the advantage that the route data is visible anywhere in the Handler’s code chain. It’s definitely preferable to create a custom property on your handler, but the Context work-around works in a pinch when you don’t’ own the handler code and have dynamic code executing as part of the handler execution. An Example of a Custom RouteHandler: Attribute Based Route Implementation In this post I’m going to discuss a custom routine implementation I built for my CallbackHandler class in the West Wind Web & Ajax Toolkit. CallbackHandler can be very easily used for creating AJAX, REST and POX requests following RPC style method mapping. You can pass parameters via URL query string, POST data or raw data structures, and you can retrieve results as JSON, XML or raw string/binary data. It’s a quick and easy way to build service interfaces with no fuss. As a quick review here’s how CallbackHandler works: You create an Http Handler that derives from CallbackHandler You implement methods that have a [CallbackMethod] Attribute and that’s it. Here’s an example of an CallbackHandler implementation in an ashx.cs based handler:// RestService.ashx.cs public class RestService : CallbackHandler { [CallbackMethod] public StockQuote GetStockQuote(string symbol) { StockServer server = new StockServer(); return server.GetStockQuote(symbol); } [CallbackMethod] public StockQuote[] GetStockQuotes(string symbolList) { StockServer server = new StockServer(); string[] symbols = symbolList.Split(new char[2] { ',',';' },StringSplitOptions.RemoveEmptyEntries); return server.GetStockQuotes(symbols); } } CallbackHandler makes it super easy to create a method on the server, pass data to it via POST, QueryString or raw JSON/XML data, and then retrieve the results easily back in various formats. This works wonderful and I’ve used these tools in many projects for myself and with clients. But one thing missing has been the ability to create clean URLs. Typical URLs looked like this: http://www.west-wind.com/WestwindWebToolkit/samples/Rest/StockService.ashx?Method=GetStockQuote&symbol=msfthttp://www.west-wind.com/WestwindWebToolkit/samples/Rest/StockService.ashx?Method=GetStockQuotes&symbolList=msft,intc,gld,slw,mwe&format=xml which works and is clear enough, but also clearly very ugly. It would be much nicer if URLs could look like this: http://www.west-wind.com//WestwindWebtoolkit/Samples/StockQuote/msfthttp://www.west-wind.com/WestwindWebtoolkit/Samples/StockQuotes/msft,intc,gld,slw?format=xml (the Virtual Root in this sample is WestWindWebToolkit/Samples and StockQuote/{symbol} is the route)(If you use FireFox try using the JSONView plug-in make it easier to view JSON content) So, taking a clue from the WCF REST tools that use RouteUrls I set out to create a way to specify RouteUrls for each of the endpoints. The change made basically allows changing the above to: [CallbackMethod(RouteUrl="RestService/StockQuote/{symbol}")] public StockQuote GetStockQuote(string symbol) { StockServer server = new StockServer(); return server.GetStockQuote(symbol); } [CallbackMethod(RouteUrl = "RestService/StockQuotes/{symbolList}")] public StockQuote[] GetStockQuotes(string symbolList) { StockServer server = new StockServer(); string[] symbols = symbolList.Split(new char[2] { ',',';' },StringSplitOptions.RemoveEmptyEntries); return server.GetStockQuotes(symbols); } where a RouteUrl is specified as part of the Callback attribute. And with the changes made with RouteUrls I can now get URLs like the second set shown earlier. So how does that work? Let’s find out… How to Create Custom Routes As mentioned earlier Routing is made up of several steps: Creating a custom RouteHandler to create HttpHandler instances Mapping the actual Routes to the RouteHandler Retrieving the RouteData and actually doing something useful with it in the HttpHandler In the CallbackHandler routing example above this works out to something like this: Create a custom RouteHandler that includes a property to track the method to call Set up the routes using Reflection against the class Looking for any RouteUrls in the CallbackMethod attribute Add a RouteData property to the CallbackHandler so we can access the RouteData in the code of the handler Creating a Custom Route Handler To make the above work I created a custom RouteHandler class that includes the actual IRouteHandler implementation as well as a generic and static method to automatically register all routes marked with the [CallbackMethod(RouteUrl="…")] attribute. Here’s the code:/// <summary> /// Route handler that can create instances of CallbackHandler derived /// callback classes. The route handler tracks the method name and /// creates an instance of the service in a predictable manner /// </summary> /// <typeparam name="TCallbackHandler">CallbackHandler type</typeparam> public class CallbackHandlerRouteHandler : IRouteHandler { /// <summary> /// Method name that is to be called on this route. /// Set by the automatically generated RegisterRoutes /// invokation. /// </summary> public string MethodName { get; set; } /// <summary> /// The type of the handler we're going to instantiate. /// Needed so we can semi-generically instantiate the /// handler and call the method on it. /// </summary> public Type CallbackHandlerType { get; set; } /// <summary> /// Constructor to pass in the two required components we /// need to create an instance of our handler. /// </summary> /// <param name="methodName"></param> /// <param name="callbackHandlerType"></param> public CallbackHandlerRouteHandler(string methodName, Type callbackHandlerType) { MethodName = methodName; CallbackHandlerType = callbackHandlerType; } /// <summary> /// Retrieves an Http Handler based on the type specified in the constructor /// </summary> /// <param name="requestContext"></param> /// <returns></returns> IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext) { IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; // If we're dealing with a Callback Handler // pass the RouteData for this route to the Handler if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; } /// <summary> /// Generic method to register all routes from a CallbackHandler /// that have RouteUrls defined on the [CallbackMethod] attribute /// </summary> /// <typeparam name="TCallbackHandler">CallbackHandler Type</typeparam> /// <param name="routes"></param> public static void RegisterRoutes<TCallbackHandler>(RouteCollection routes) { // find all methods var methods = typeof(TCallbackHandler).GetMethods(BindingFlags.Instance | BindingFlags.Public); foreach (var method in methods) { var attrs = method.GetCustomAttributes(typeof(CallbackMethodAttribute), false); if (attrs.Length < 1) continue; CallbackMethodAttribute attr = attrs[0] as CallbackMethodAttribute; if (string.IsNullOrEmpty(attr.RouteUrl)) continue; // Add the route routes.Add(method.Name, new Route(attr.RouteUrl, new CallbackHandlerRouteHandler(method.Name, typeof(TCallbackHandler)))); } } } The RouteHandler implements IRouteHandler, and its responsibility via the GetHandler method is to create an HttpHandler based on the route data. When ASP.NET calls GetHandler it passes a requestContext parameter which includes a requestContext.RouteData property. This parameter holds the current request’s route data as well as an instance of the current RouteHandler. If you look at GetHttpHandler() you can see that the code creates an instance of the handler we are interested in and then sets the RouteData property on the handler. This is how you can pass the current request’s RouteData to the handler. The RouteData object also has a  RouteData.RouteHandler property that is also available to the Handler later, which is useful in order to get additional information about the current route. In our case here the RouteHandler includes a MethodName property that identifies the method to execute in the handler since that value no longer comes from the URL so we need to figure out the method name some other way. The method name is mapped explicitly when the RouteHandler is created and here the static method that auto-registers all CallbackMethods with RouteUrls sets the method name when it creates the routes while reflecting over the methods (more on this in a minute). The important point here is that you can attach additional properties to the RouteHandler and you can then later access the RouteHandler and its properties later in the Handler to pick up these custom values. This is a crucial feature in that the RouteHandler serves in passing additional context to the handler so it knows what actions to perform. The automatic route registration is handled by the static RegisterRoutes<TCallbackHandler> method. This method is generic and totally reusable for any CallbackHandler type handler. To register a CallbackHandler and any RouteUrls it has defined you simple use code like this in Application_Start (or other application startup code):protected void Application_Start(object sender, EventArgs e) { // Register Routes for RestService CallbackHandlerRouteHandler.RegisterRoutes<RestService>(RouteTable.Routes); } If you have multiple CallbackHandler style services you can make multiple calls to RegisterRoutes for each of the service types. RegisterRoutes internally uses reflection to run through all the methods of the Handler, looking for CallbackMethod attributes and whether a RouteUrl is specified. If it is a new instance of a CallbackHandlerRouteHandler is created and the name of the method and the type are set. routes.Add(method.Name,           new Route(attr.RouteUrl, new CallbackHandlerRouteHandler(method.Name, typeof(TCallbackHandler) )) ); While the routing with CallbackHandlerRouteHandler is set up automatically for all methods that use the RouteUrl attribute, you can also use code to hook up those routes manually and skip using the attribute. The code for this is straightforward and just requires that you manually map each individual route to each method you want a routed: protected void Application_Start(objectsender, EventArgs e){    RegisterRoutes(RouteTable.Routes);}void RegisterRoutes(RouteCollection routes) { routes.Add("StockQuote Route",new Route("StockQuote/{symbol}",                     new CallbackHandlerRouteHandler("GetStockQuote",typeof(RestService) ) ) );     routes.Add("StockQuotes Route",new Route("StockQuotes/{symbolList}",                     new CallbackHandlerRouteHandler("GetStockQuotes",typeof(RestService) ) ) );}I think it’s clearly easier to have CallbackHandlerRouteHandler.RegisterRoutes() do this automatically for you based on RouteUrl attributes, but some people have a real aversion to attaching logic via attributes. Just realize that the option to manually create your routes is available as well. Using the RouteData in the Handler A RouteHandler’s responsibility is to create an HttpHandler and as mentioned earlier, natively IHttpHandler doesn’t have any support for RouteData. In order to utilize RouteData in your handler code you have to pass the RouteData to the handler. In my CallbackHandlerRouteHandler when it creates the HttpHandler instance it creates the instance and then assigns the custom RouteData property on the handler:IHttpHandler handler = Activator.CreateInstance(CallbackHandlerType) as IHttpHandler; if (handler is CallbackHandler) ((CallbackHandler)handler).RouteData = requestContext.RouteData; return handler; Again this only works if you actually add a RouteData property to your handler explicitly as I did in my CallbackHandler implementation:/// <summary> /// Optionally store RouteData on this handler /// so we can access it internally /// </summary> public RouteData RouteData {get; set; } and the RouteHandler needs to set it when it creates the handler instance. Once you have the route data in your handler you can access Route Keys and Values and also the RouteHandler. Since my RouteHandler has a custom property for the MethodName to retrieve it from within the handler I can do something like this now to retrieve the MethodName (this example is actually not in the handler but target is an instance pass to the processor): // check for Route Data method name if (target is CallbackHandler) { var routeData = ((CallbackHandler)target).RouteData; if (routeData != null) methodToCall = ((CallbackHandlerRouteHandler)routeData.RouteHandler).MethodName; } When I need to access the dynamic values in the route ( symbol in StockQuote/{symbol}) I can retrieve it easily with the Values collection (RouteData.Values["symbol"]). In my CallbackHandler processing logic I’m basically looking for matching parameter names to Route parameters: // look for parameters in the routeif(routeData != null){    string parmString = routeData.Values[parameter.Name] as string;    adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType);} And with that we’ve come full circle. We’ve created a custom RouteHandler() that passes the RouteData to the handler it creates. We’ve registered our routes to use the RouteHandler, and we’ve utilized the route data in our handler. For completeness sake here’s the routine that executes a method call based on the parameters passed in and one of the options is to retrieve the inbound parameters off RouteData (as well as from POST data or QueryString parameters):internal object ExecuteMethod(string method, object target, string[] parameters, CallbackMethodParameterType paramType, ref CallbackMethodAttribute callbackMethodAttribute) { HttpRequest Request = HttpContext.Current.Request; object Result = null; // Stores parsed parameters (from string JSON or QUeryString Values) object[] adjustedParms = null; Type PageType = target.GetType(); MethodInfo MI = PageType.GetMethod(method, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic); if (MI == null) throw new InvalidOperationException("Invalid Server Method."); object[] methods = MI.GetCustomAttributes(typeof(CallbackMethodAttribute), false); if (methods.Length < 1) throw new InvalidOperationException("Server method is not accessible due to missing CallbackMethod attribute"); if (callbackMethodAttribute != null) callbackMethodAttribute = methods[0] as CallbackMethodAttribute; ParameterInfo[] parms = MI.GetParameters(); JSONSerializer serializer = new JSONSerializer(); RouteData routeData = null; if (target is CallbackHandler) routeData = ((CallbackHandler)target).RouteData; int parmCounter = 0; adjustedParms = new object[parms.Length]; foreach (ParameterInfo parameter in parms) { // Retrieve parameters out of QueryString or POST buffer if (parameters == null) { // look for parameters in the route if (routeData != null) { string parmString = routeData.Values[parameter.Name] as string; adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType); } // GET parameter are parsed as plain string values - no JSON encoding else if (HttpContext.Current.Request.HttpMethod == "GET") { // Look up the parameter by name string parmString = Request.QueryString[parameter.Name]; adjustedParms[parmCounter] = ReflectionUtils.StringToTypedValue(parmString, parameter.ParameterType); } // POST parameters are treated as methodParameters that are JSON encoded else if (paramType == CallbackMethodParameterType.Json) //string newVariable = methodParameters.GetValue(parmCounter) as string; adjustedParms[parmCounter] = serializer.Deserialize(Request.Params["parm" + (parmCounter + 1).ToString()], parameter.ParameterType); else adjustedParms[parmCounter] = SerializationUtils.DeSerializeObject( Request.Params["parm" + (parmCounter + 1).ToString()], parameter.ParameterType); } else if (paramType == CallbackMethodParameterType.Json) adjustedParms[parmCounter] = serializer.Deserialize(parameters[parmCounter], parameter.ParameterType); else adjustedParms[parmCounter] = SerializationUtils.DeSerializeObject(parameters[parmCounter], parameter.ParameterType); parmCounter++; } Result = MI.Invoke(target, adjustedParms); return Result; } The code basically uses Reflection to loop through all the parameters available on the method and tries to assign the parameters from RouteData, QueryString or POST variables. The parameters are converted into their appropriate types and then used to eventually make a Reflection based method call. What’s sweet is that the RouteData retrieval is just another option for dealing with the inbound data in this scenario and it adds exactly two lines of code plus the code to retrieve the MethodName I showed previously – a seriously low impact addition that adds a lot of extra value to this endpoint callback processing implementation. Debugging your Routes If you create a lot of routes it’s easy to run into Route conflicts where multiple routes have the same path and overlap with each other. This can be difficult to debug especially if you are using automatically generated routes like the routes created by CallbackHandlerRouteHandler.RegisterRoutes. Luckily there’s a tool that can help you out with this nicely. Phill Haack created a RouteDebugging tool you can download and add to your project. The easiest way to do this is to grab and add this to your project is to use NuGet (Add Library Package from your Project’s Reference Nodes):   which adds a RouteDebug assembly to your project. Once installed you can easily debug your routes with this simple line of code which needs to be installed at application startup:protected void Application_Start(object sender, EventArgs e) { CallbackHandlerRouteHandler.RegisterRoutes<StockService>(RouteTable.Routes); // Debug your routes RouteDebug.RouteDebugger.RewriteRoutesForTesting(RouteTable.Routes); } Any routed URL then displays something like this: The screen shows you your current route data and all the routes that are mapped along with a flag that displays which route was actually matched. This is useful – if you have any overlap of routes you will be able to see which routes are triggered – the first one in the sequence wins. This tool has saved my ass on a few occasions – and with NuGet now it’s easy to add it to your project in a few seconds and then remove it when you’re done. Routing Around Custom routing seems slightly complicated on first blush due to its disconnected components of RouteHandler, route registration and mapping of custom handlers. But once you understand the relationship between a RouteHandler, the RouteData and how to pass it to a handler, utilizing of Routing becomes a lot easier as you can easily pass context from the registration to the RouteHandler and through to the HttpHandler. The most important thing to understand when building custom routing solutions is to figure out how to map URLs in such a way that the handler can figure out all the pieces it needs to process the request. This can be via URL routing parameters and as I did in my example by passing additional context information as part of the RouteHandler instance that provides the proper execution context. In my case this ‘context’ was the method name, but it could be an actual static value like an enum identifying an operation or category in an application. Basically user supplied data comes in through the url and static application internal data can be passed via RouteHandler property values. Routing can make your application URLs easier to read by non-techie types regardless of whether you’re building Service type or REST applications, or full on Web interfaces. Routing in ASP.NET 4.0 makes it possible to create just about any extensionless URLs you can dream up and custom RouteHanmdler References Sample ProjectIncludes the sample CallbackHandler service discussed here along with compiled versionsof the Westwind.Web and Westwind.Utilities assemblies.  (requires .NET 4.0/VS 2010) West Wind Web Toolkit includes full implementation of CallbackHandler and the Routing Handler West Wind Web Toolkit Source CodeContains the full source code to the Westwind.Web and Westwind.Utilities assemblies usedin these samples. Includes the source described in the post.(Latest build in the Subversion Repository) CallbackHandler Source(Relevant code to this article tree in Westwind.Web assembly) JSONView FireFoxPluginA simple FireFox Plugin to easily view JSON data natively in FireFox.For IE you can use a registry hack to display JSON as raw text.© Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  AJAX  HTTP  

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  • Design by Contract with Microsoft .Net Code Contract

    - by Fredrik N
    I have done some talks on different events and summits about Defensive Programming and Design by Contract, last time was at Cornerstone’s Developer Summit 2010. Next time will be at SweNug (Sweden .Net User Group). I decided to write a blog post about of some stuffs I was talking about. Users are a terrible thing! Protect your self from them ”Human users have a gift for doing the worst possible thing at the worst possible time.” – Michael T. Nygard, Release It! The kind of users Michael T. Nygard are talking about is the users of a system. We also have users that uses our code, the users I’m going to focus on is the users of our code. Me and you and another developers. “Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” – Martin Fowler Good programmers also writes code that humans know how to use, good programmers also make sure software behave in a predictable manner despise inputs or user actions. Design by Contract   Design by Contract (DbC) is a way for us to make a contract between us (the code writer) and the users of our code. It’s about “If you give me this, I promise to give you this”. It’s not about business validations, that is something completely different that should be part of the domain model. DbC is to make sure the users of our code uses it in a correct way, and that we can rely on the contract and write code in a way where we know that the users will follow the contract. It will make it much easier for us to write code with a contract specified. Something like the following code is something we may see often: public void DoSomething(Object value) { value.DoIKnowThatICanDoThis(); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Where “value” can be uses directly or passed to other methods and later be used. What some of us can easily forget here is that the “value” can be “null”. We will probably not passing a null value, but someone else that uses our code maybe will do it. I think most of you (including me) have passed “null” into a method because you don’t know if the argument need to be specified to a valid value etc. I bet most of you also have got the “Null reference exception”. Sometimes this “Null reference exception” can be hard and take time to fix, because we need to search among our code to see where the “null” value was passed in etc. Wouldn’t it be much better if we can as early as possible specify that the value can’t not be null, so the users of our code also know it when the users starts to use our code, and before run time execution of the code? This is where DbC comes into the picture. We can use DbC to specify what we need, and by doing so we can rely on the contract when we write our code. So the code above can actually use the DoIKnowThatICanDoThis() method on the value object without being worried that the “value” can be null. The contract between the users of the code and us writing the code, says that the “value” can’t be null.   Pre- and Postconditions   When working with DbC we are specifying pre- and postconditions.  Precondition is a condition that should be met before a query or command is executed. An example of a precondition is: “The Value argument of the method can’t be null”, and we make sure the “value” isn’t null before the method is called. Postcondition is a condition that should be met when a command or query is completed, a postcondition will make sure the result is correct. An example of a postconditon is “The method will return a list with at least 1 item”. Commands an Quires When using DbC, we need to know what a Command and a Query is, because some principles that can be good to follow are based on commands and queries. A Command is something that will not return anything, like the SQL’s CREATE, UPDATE and DELETE. There are two kinds of Commands when using DbC, the Creation commands (for example a Constructor), and Others. Others can for example be a Command to add a value to a list, remove or update a value etc. //Creation commands public Stack(int size) //Other commands public void Push(object value); public void Remove(); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   A Query, is something that will return something, for example an Attribute, Property or a Function, like the SQL’s SELECT.   There are two kinds of Queries, the Basic Queries  (Quires that aren’t based on another queries), and the Derived Queries, queries that is based on another queries. Here is an example of queries of a Stack: //Basic Queries public int Count; public object this[int index] { get; } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To understand about some principles that are good to follow when using DbC, we need to know about the Commands and different Queries. The 6 Principles When working with DbC, it’s advisable to follow some principles to make it easier to define and use contracts. The following DbC principles are: Separate commands and queries. Separate basic queries from derived queries. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries. For each command, write a postcondition that specifies the value of every basic query. For every query and command, decide on a suitable precondition. Write invariants to define unchanging properties of objects. Before I will write about each of them I want you to now that I’m going to use .Net 4.0 Code Contract. I will in the rest of the post uses a simple Stack (Yes I know, .Net already have a Stack class) to give you the basic understanding about using DbC. A Stack is a data structure where the first item in, will be the first item out. Here is a basic implementation of a Stack where not contract is specified yet: public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } //Is related to Count and this[] Query public object Top() { return this[Count]; } //Creation commands public Stack(uint size) { Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { this[++Count] = value; } public void Remove() { this[Count] = null; Count--; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The Stack is implemented in a way to demonstrate the use of Code Contract in a simple way, the implementation may not look like how you would implement it, so don’t think this is the perfect Stack implementation, only used for demonstration.   Before I will go deeper into the principles I will simply mention how we can use the .Net Code Contract. I mention before about pre- and postcondition, is about “Require” something and to “Ensure” something. When using Code Contract, we will use a static class called “Contract” and is located in he “System.Diagnostics.Contracts” namespace. The contract must be specified at the top or our member statement block. To specify a precondition with Code Contract we uses the Contract.Requires method, and to specify a postcondition, we uses the Contract.Ensure method. Here is an example where both a pre- and postcondition are used: public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The contract above requires that the Count is greater than 0, if not we can’t get the item at the Top of a Stack. We also Ensures that the results (By using the Contract.Result method, we can specify a postcondition that will check if the value returned from a method is correct) of the Top query is equal to this[Count].   1. Separate Commands and Queries   When working with DbC, it’s important to separate Command and Quires. A method should either be a command that performs an Action, or returning information to the caller, not both. By asking a question the answer shouldn’t be changed. The following is an example of a Command and a Query of a Stack: public void Push(object value) public object Top() .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The Push is a command and will not return anything, just add a value to the Stack, the Top is a query to get the item at the top of the stack.   2. Separate basic queries from derived queries There are two different kinds of queries,  the basic queries that doesn’t rely on another queries, and derived queries that uses a basic query. The “Separate basic queries from derived queries” principle is about about that derived queries can be specified in terms of basic queries. So this principles is more about recognizing that a query is a derived query or a basic query. It will then make is much easier to follow the other principles. The following code shows a basic query and a derived query: //Basic Queries public uint Count; //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   We can see that IsEmpty will use the Count query, and that makes the IsEmpty a Derived query.   3. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries.   When the derived query is recognize we can follow the 3ed principle. For each derived query, we can create a postcondition that specifies what result our derived query will return in terms of one or more basic queries. Remember that DbC is about contracts between the users of the code and us writing the code. So we can’t use demand that the users will pass in a valid value, we must also ensure that we will give the users what the users wants, when the user is following our contract. The IsEmpty query of the Stack will use a Count query and that will make the IsEmpty a Derived query, so we should now write a postcondition that specified what results will be returned, in terms of using a basic query and in this case the Count query, //Basic Queries public uint Count; //Derived Queries public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } The Contract.Ensures is used to create a postcondition. The above code will make sure that the results of the IsEmpty (by using the Contract.Result to get the result of the IsEmpty method) is correct, that will say that the IsEmpty will be either true or false based on Count is equal to 0 or not. The postcondition are using a basic query, so the IsEmpty is now following the 3ed principle. We also have another Derived Query, the Top query, it will also need a postcondition and it uses all basic queries. The Result of the Top method must be the same value as the this[] query returns. //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count and this[] Query public object Top() { Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   4. For each command, write a postcondition that specifies the value of every basic query.   For each command we will create a postconditon that specifies the value of basic queries. If we look at the Stack implementation we will have three Commands, one Creation command, the Constructor, and two others commands, Push and Remove. Those commands need a postcondition and they should include basic query to follow the 4th principle. //Creation commands public Stack(uint size) { Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   As you can see the Create command will Ensures that Count will be 0 when the Stack is created, when a Stack is created there shouldn’t be any items in the stack. The Push command will take a value and put it into the Stack, when an item is pushed into the Stack, the Count need to be increased to know the number of items added to the Stack, and we must also make sure the item is really added to the Stack. The postconditon of the Push method will make sure the that old value of the Count (by using the Contract.OldValue we can get the value a Query has before the method is called)  plus 1 will be equal to the Count query, this is the way we can ensure that the Push will increase the Count with one. We also make sure the this[] query will now contain the item we pushed into the Stack. The Remove method must make sure the Count is decreased by one when the top item is removed from the Stack. The Commands is now following the 4th principle, where each command now have a postcondition that used the value of basic queries. Note: The principle says every basic Query, the Remove only used one Query the Count, it’s because this command can’t use the this[] query because an item is removed, so the only way to make sure an item is removed is to just use the Count query, so the Remove will still follow the principle.   5. For every query and command, decide on a suitable precondition.   We have now focused only on postcondition, now time for some preconditons. The 5th principle is about deciding a suitable preconditon for every query and command. If we starts to look at one of our basic queries (will not go through all Queries and commands here, just some of them) the this[] query, we can’t pass an index that is lower then 1 (.Net arrays and list are zero based, but not the stack in this blog post ;)) and the index can’t be lesser than the number of items in the stack. So here we will need a preconditon. public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Think about the Contract as an documentation about how to use the code in a correct way, so if the contract could be specified elsewhere (not part of the method body), we could simply write “return _array[index]” and there is no need to check if index is greater or lesser than Count, because that is specified in a “contract”. The implementation of Code Contract, requires that the contract is specified in the code. As a developer I would rather have this contract elsewhere (Like Spec#) or implemented in a way Eiffel uses it as part of the language. Now when we have looked at one Query, we can also look at one command, the Remove command (You can see the whole implementation of the Stack at the end of this blog post, where precondition is added to more queries and commands then what I’m going to show in this section). We can only Remove an item if the Count is greater than 0. So we can write a precondition that will require that Count must be greater than 0. public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   6. Write invariants to define unchanging properties of objects.   The last principle is about making sure the object are feeling great! This is done by using invariants. When using Code Contract we can specify invariants by adding a method with the attribute ContractInvariantMethod, the method must be private or public and can only contains calls to Contract.Invariant. To make sure the Stack feels great, the Stack must have 0 or more items, the Count can’t never be a negative value to make sure each command and queries can be used of the Stack. Here is our invariant for the Stack object: [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The ObjectInvariant method will be called every time after a Query or Commands is called. Here is the full example using Code Contract:   public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } set { Contract.Requires(index >= 1); Contract.Requires(index <= Count); _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } //Is related to Count and this[] Query public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } //Creation commands public Stack(uint size) { Contract.Requires(size > 0); Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Requires(value != null); Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Summary By using Design By Contract we can make sure the users are using our code in a correct way, and we must also make sure the users will get the expected results when they uses our code. This can be done by specifying contracts. To make it easy to use Design By Contract, some principles may be good to follow like the separation of commands an queries. With .Net 4.0 we can use the Code Contract feature to specify contracts.

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