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• Triple (3) Monitors under Linux

  - by widgisoft

  I have a 3 monitor setup (each 1680x1050) via an Nvidia NVS440 (2 GPUs, 2 outputs per GPU totalling 4 outputs); this works fine under Windows XP,7 but caused considerable headaches under Linux (Ubuntu 9.04). I had previously used an XFX 9600GT and the onboard XFX 9300GS to produce the same result but the card was noisy and power hungry and I was hoping that there was some magical switch in the NVS4400 that got rid of this annoying problem - turns out the NVS440 is just 2 cards on one physical PCB :-p (I searched the net high and low for people using this card under Linux but found nothing, if anything the card uses less power and is fan less so I was to benefit from it either way) Anyway, using either set up there were 5 solutions available: Have 3 separate X instances, all un joined Have 3 separate X instances, adjoined by Xinerama Have 2 separate X instances - One using twin-view, both adjoined by Xinerama Have 2 separate X instances - One using twin-view but no Xinerama Have a single Twin-view setup and leave the 3rd screen unplugged :-p The 4rd option, using 2 separate X instances and twinview (but no xinerama) was the best balance in terms of performance and usability but caused 2 really annoying issues You couldn't control (without altering the shortcuts) which screen an application opened onto - and once it was opened you couldn't move it to another screen without opening up terminal and forcing it to move Nvidia's overriding or falsifying of Xinerama breaks and the 2 screens joined by Twin view behave like a single huge screen causing popups to open in the middle of both screens and maximising of windows stretches to the width of the first 2 screens Firefox can only run one instance as the same user so having multiple firefox windows requires at least 2 users The second option "feels" like the right option, but OpenGL is basically disabled and playing any sort of game or even running anything graphical causes a huge performance drop and instability - even trying to run a basic emulator for gba or gens just causes the system to fall over. It works just enough to stare at your desktop and do nothing but as soon as you start doing some work - opening windows, dragging things around - running multiple copies of firefox it just really feels slow. The last open, only going dual screen works perfectly and everything performs as required, full GPU acceleration - two logical screen spaces - perfect, just make it work across GPUs like windows! :-p Anyway, I know RandR was supposed to pick up the slack when it would introduced GPU objects of sorts to allow multiple GPUs to be stitched together to create one huge desktop at a much deeper layer than Xinerama. I was wondering if this has now been fixed (I noticed X server 1.7 is out) and whether anyone has got it running successfully? Again, my requirements are: One huge desktop to drag any window across Maximising of windows to each screen (as XP does) Running fullscreen apps on the primary screen and disabling the mouse from moving onto the others or on all 3 stretched Finally as a side note; I am aware of the Matrox triple (and dual) head splitter but even the price they go for on eBay is more than I can afford atm, my argument: I shouldn't have to buy extra hardware to get something to work on Linux when it's something that's existed in the windows world for a long time (can you tell I don't get on with X :-p); If I had the cash I'd have bought the latest version of this box already (the new version finally supports large resolutions as the displays I have 1680x1050 each).

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• How to flip video feed that's presented upside down?

  - by Zuul

  Skype an other applications running under windows 7 Ultimate are presenting the video captured from the laptop built-in webcam upside down. I've tried many solution that I was able to find regarding issues like this, but to no avail. Some of the most relevant are discussed here: From Skype Support Network, the thread why is my video image of myself upside-down??? From ASUSTek Forums, the thread Built-in camera upside down Both present several potential solutions to this issue, but I've been unable to fix it for the laptop ASUS U6S. What I've already tried: Changing Drivers The driver that works must be the one from Windows, all others available from ASUS drivers either don't install or install but the webcam doesn't provide any video feed. This disallows all options that concern using an older driver or editing the .inf file as to manually adjust the settings. ASUS does not provide drivers for Windows 7, so I've used drivers from Windows Vista 32 Bit. Using the application manycam This application actually solves the issue (temporarily), but creates new ones: If I use the application to flip the video feed, Skype video call cease to work. This application doesn't save the settings, at least I wasn't able to find any way to save the settings I've used to flip the video feed. A computer restart brings all back to how it was, video feed upside down and if the application is still installed, Skype continues to fail on video calls. Regedit I've searched thru Windows Registry Editor as to find any reference to the webcam settings, hopping to find a key with the Flip parameter, since it's up to the driver to flip the image (by what I could ascertain from this problem). Couldn't find any reference to such settings, either they actually don't exist within the Windows Registry or they use some weird name that I could think off. System Configuration I was able to access the webcam system settings from the Windows Device Manager, but the tab that actually has the Image Rotation setting is always disabled. The same goes for the settings available from the Skype webcam options (that essentially is presenting the same settings as Windows Device Manager, just within a custom Skype pop-up). Question: How can I flip the video feed from the laptop's built-in webcam, as to properly see and broadcast the video?

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• Be your own cloud [closed]

  - by Jedi

  I have reasonably many electronic gadgets that can go LAN or WI-FI. But how do you share and/or syncronize all your files among them? Well, between my laptops and my desktop I use Dropbox. A nice way to share files among computers. But what if your HDD on your laptop is not large enough to carry music, pictures and films. Normally you would buy an extern USB HDD and store them there, but then you cannot reach the files from other computers which are not connected to the USB device. Many would say I should use a solution like a cloud with a disc station or something like that. But my needs are follows: A mass storage which can be reached among devices (laptops, desktops, iPhone, Android phone, XBox or Playstation). Has low power requirements and is silent. Can be reached inside home and it would be nice if it could be reached outside home as well. Cheap I have looked around and I have found an wireless router which can share a USB device: D-Link Wireless N HD Media Router. I thought it would be an interesting solution for a simple local cloud solution. D-Link uses a little program called SharePort Plus which mount the USB device to your computer. Unfortunately is the transfer rate to the USB storage device rather disappointing. The transfer rate was 5.8 Mbps even though the distance between the laptop and the router was 2 meter. The same is happening when I use cable from the computer to the router. Another thing is that SharePort Plus only allows one computer be connected to the device at a time. The last thing was something I could live with. I have search on the Internet for other solutions and found this video from Synology. I'm not sure if their solution is the right one. I think a disc station connected to my home LAN could the right solution. What have you done in your home to store and share files among your computers and game consoles?

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• Nginx fastcgi problems with django (double slashes in url?)

  - by wizard

  I'm deploying my first django app. I'm familiar with nginx and fastcgi from deploying php-fpm. I can't get python to recognize the urls. I'm also at a loss on how to debug this further. I'd welcome solutions to this problem and tips on debugging fastcgi problems. Currently I get a 404 page regardless of the url and for some reason a double slash For http://www.site.com/admin/ Page not found (404) Request Method: GET Request URL: http://www.site.com/admin// My urls.py from the debug output - which work in the dev server. Using the URLconf defined in ahrlty.urls, Django tried these URL patterns, in this order: ^listings/ ^admin/ ^accounts/login/$ ^accounts/logout/$ my nginx config server { listen 80; server_name beta.ahrlty.com; access_log /home/ahrlty/ahrlty/logs/access.log; error_log /home/ahrlty/ahrlty/logs/error.log; location /static/ { alias /home/ahrlty/ahrlty/ahrlty/static/; break; } location /media/ { alias /usr/lib/python2.6/dist-packages/django/contrib/admin/media/; break; } location / { include /etc/nginx/fastcgi_params; fastcgi_pass 127.0.0.1:8001; break; } } and my fastcgi_params fastcgi_param QUERY_STRING $query_string; fastcgi_param REQUEST_METHOD $request_method; fastcgi_param CONTENT_TYPE $content_type; fastcgi_param CONTENT_LENGTH $content_length; fastcgi_param SCRIPT_NAME $fastcgi_script_name; fastcgi_param REQUEST_URI $request_uri; fastcgi_param DOCUMENT_URI $document_uri; fastcgi_param DOCUMENT_ROOT $document_root; fastcgi_param SERVER_PROTOCOL $server_protocol; fastcgi_param GATEWAY_INTERFACE CGI/1.1; fastcgi_param SERVER_SOFTWARE nginx/$nginx_version; fastcgi_param REMOTE_ADDR $remote_addr; fastcgi_param REMOTE_PORT $remote_port; fastcgi_param SERVER_ADDR $server_addr; fastcgi_param SERVER_PORT $server_port; fastcgi_param SERVER_NAME $server_name; fastcgi_param PATH_INFO $fastcgi_script_name; # PHP only, required if PHP was built with --enable-force-cgi-redirect fastcgi_param REDIRECT_STATUS 200; And lastly I'm running fastcgi from the commandline with django's manage.py. python manage.py runfcgi method=threaded host=127.0.0.1 port=8080 pidfile=mysite.pid minspare=4 maxspare=30 daemonize=false I'm having a hard time debugging this one. Does anything jump out at anybody? Notes nginx version: nginx/0.7.62 Django svn trunk rev 13013

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• Sharing files between multiple sites using only desktop software

  - by perlyking

  Our organisation has three sites; a head office, where the master copies of company files are stored, plus two branch offices using only workstations and a NAS or two. Currently we're talking about <10GB. At the main office, we have no admin access to the file server, as this is entirely controlled by the larger institution where we are located. For the same reason, we have no VPN remote access to this network. Instead, we simply have access to a network share using over a Novell LAN. Question: how can we share files between offices in way that minimises latency, i.e. that gives us a mirror of the main network share at each site? (There is little likelihood of concurrent editing, and we can live with the odd file conflict now and again). Up to now branch office staff have had to use GotoMyPC-type solutions to remotely access files held at the main office. Or email. I was hoping to use Google Drive on a dedicated workstation at each office to sync the contents of the network share (head office) or NAS (branch offices) via the cloud, but at my last attempt (29 Jun '12), the Google Drive installer would not allow me to designate the remote network share as the "target" folder. (I chose Google Drive over Drobbox et al. as we already use GMail for corporate mail) The next idea was to use a designated workstation at head office to mirror the network share to a local drive, then use Google Drive to push that to the cloud. This seems a step too far. Nor do I have any good ideas about how to achieve this network/local mirroring, as we can't, for example, install the rsync daemon on the server. I do not want to use Google Drive locally on each workstation as this will inconvenience users, and more importantly, move files off the backed-up, well-maintained (UPS, RAID etc) network share at head office. Our budget is only in the £100's. Should we perhaps just ditch the head office server and use something like JungleDisk? At least this presents the user with what appears to be a mapped drive.

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• How to run a restricted set of programs with Administrator privileges without giving up Admin acces (Win7 Pro)

  - by frLich

  I have a shared system, running Windows7 X64, restricted to a 'standard user' with no password. Not everyone who has access to the system has the administrator password. This works rather well, except for some applications - specially the unlock-applications for encrypted hard drives/USB flash drives. The specific ones either require Administrator access (eg. Seagate Blackarmor) or simply fail without it -- since these programs are sending raw commands to a device, this is to be expected. I would like to be able to add the hashes of these particular programs to a whitelist, and have them run as administrator without needing any prompts. Since these are by definition on removable media, I can't simply use a filename or even a path. One of the users who shares the system can be considered 'crafty', so anything which temporarily grants administrator rights to an user account is certain to cause problems. What i'd like to be able to do: 1) Create an admin account that can only run programs from a whitelist (or, failing that, from a directory) I can't find a good way to do this: As far as I can tell, SRP applies equally to ALL users? Even if I put a "Deny" token on all directories on the system, such that new directories would inherit it, it could still potentially run things from the mounted USB devices. I also don't know whether it's possible to create a new directory that DOESN'T inherit from the parent, that would lake the deny token, and provide admin access. 2) Find a lightweight service that will run these programs in its local context Windows7 seems to block cross-privilege level communication by default, and I haven't found such for windows 7. One example seems to be "sudo" (http://pages.cpsc.ucalgary.ca/~nfriess/sudo/) but because it uses a WLNOTIFY hook, it won't work under Vista nor Windows7 Non-Solutions: - RunAs: Requires administrator password! (but everyone calls it "sudo" anyway) - RunAs /savecred: Nice idea, but appears to be completely insecure. - RUNASSPC - Same concept as RunAs, uses "encrypted" files with credentials, but checks in user-space. - Scheduled Tasks - "Fixed" permissions make this difficult, and doesn't support interactive processes even if it did. - SuRun: From Google: "Surun uses its own Windows service that adds the user to the group of administrators during program start and removes him automatically from that group again"

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• Which hardware to VM ratio for Build-Server virtualization?

  - by Martin

  Let's start with saying that I'm a total noob wrt. to server virtualization. That is, I use VMs often during development, but they're simple desktop machine things for me. Now to my problem: We have two (physical) build servers, one master, one slave running Jenkins to do daily tasks and build (Visual C++ Builds) our release packages for our software. As such these machines are critical to our company, because we do lot's releases and without a controlled environment to create them, we can't ship fixes. (And currently there's no proper backup of these machines in place, because they do not hold any data as such - it just would be a major pain to setup them again should they go bust. (But setting up backup that I'd know would work in case of HW failure would even be more pain, so we have skipped that until now.)) Therefore (and for scaling purposes) we would like to go virtual with these machines. Outsourcing to the cloud is not an option, not at all, so we'll have to use on-premises hardware and VM hosts. Each Build-Server (master or slave) is a fully configured (installs, licenses, shares in case of the master, ...) Windows Server box. I would now ideally like to just convert the (two) existing physical nodes to VM images and run them. Later add more VM slave instances as clones of the existing ones. And here begin my questions: Should I go for one VM per one hardware-box or should I go for something where a single hardware runs multiple VMs? That would mean a single point of failure hardware wise and doesn't seem like a good idea ... or?? Since we're doing C++ compilation with Visual Studio, I assume that during a build the hardware (processor cores + disk) will be fully utilized, so going with more than one build-node per hardware doesn't seem to make much sense?? Wrt. to hardware options, does it make any difference which VM software we use (VMWare, MS, Virtualbox, ... ?) (We're using Windows exclusively for our builds.) Regarding budget: We have a normal small company (20 developers) budget for this. ;-) That is, if it's going to cost a few k$ it's going to cost. If it's free - the better. I strongly prefer solutions where there's no multi-k$ maintenance costs per year.

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• 20GB+ worth of emails in my /home what is a better solution for that?

  - by Skinkie

  My email storage requirements are outgrowing anything reasonable with respect to local mail storage. As we speak 99% of my home partition is filled with personal mail in Thunderbirds mail dirs. Needless to say, this is just painful, badly searchable and as history has proven me that backups work, but Thunderbird is capable of loosing a lot of mail very easily. Currently I have an remote IMAPS server (Dovecot) running for my daily mail, accessible from anywhere, which from my own practice works efficiently up to about 1000 emails. Then some archive directories should be used to move mail around. I have been looking into DBMail, but I wonder if I make my case worse or better which such solution. None of the supported database employ string deduplication or string compression out of the box, so is this going to help me with 20GB+ mail? What about falling back to a plain old IMAP server? A filesystem like ZFS would support stuff like GZIP transparently, which could help. Could someone share their thoughts? The 20GB mostly consists of mailinglists, and normal mail. Not things like attachments. To add some clarifications; As we speak, my mail is not server side indexed at all - only my new mail arrives at a remote IMAP server. It is all local storage from former POP3 accounts, local mirrored Gmail and IMAP accounts. In my perspective it is not Thunderbird that sucks, its fileformat that sucks. Regarding the 1000 mails. On the road I am using Alpine and MobileMail, quite happy with both of them, but some management is required to actually manage the mail. Sieve helps a lot with that, but browing through 10.000 e-mails is not fun, especially not on a mobile client. I am quite happy with Dovecot, never had any issues with it. I just wonder if this is the way to go. Or if there are any other better solutions. What my question is: what is the best practice solution that allows 20GB+ mails and is -on demand remotely accessible, easy to backup and archive worthy. It doesn't need to be available 24x7. The final approach I took was installing a local IMAP server (Dovecot), configured it for being my archive, using the following guide: http://en.gentoo-wiki.com/wiki/Dovecot/InstallThunderbird

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• IE9 Error: There was a pr?blem sending the command to the program

  - by HK1

  I'm working on a new/fresh Windows 7 32bit machine that now has IE9 installed. The user is using the Dell Stardock application as his primary "desktop" (all his links there). When we place an internet link there and click on it we get the following error message: There was a problem sending the command to the program. To me this indicates that IE9 is having trouble going to the website we want to go to, which should get passed as a parameter to the browser when it opens. I don't think this is a StarDock/ObjectDock problem because we also have some other problems with internet links. For example, we cannot move an internet link from the Desktop to the Quick Launch on the task bar. When we do try, it forces us to put the link with the IE icon as part of the IE menu instead of allowing us to have a shortcut there as it's own entry. I should mention however, that links on the desktop and in the taskbar do work as we expect them too (without showing the above error message). It appears that this problem started after installing Windows Updates. Since we installed a whole bunch of updates at once I have no idea which one caused the problem. I did have Google Chrome installed but I uninstalled it since the user wants to use IE. The problem started before I uninstalled Chrome. I also reset the browser settings on IE9. It didn't help. Next I uninstalled IE9 which took me back to IE8. This actually did resolve the problem but the problem came back as soon as I installed IE9 again. We have Verizon Internet Security installed. It's actually a McAfee product rebranded to look like Verizon. I'm not real crazy over this software but the customer has a subscription so we're not planning to change it. I have no reason to believe that this is causing the problem and yet I know that security software is often to blame for strange issues. I've looked at the registry settings for the following keys and everything appears to be ok for every single one of them: HKEY_CLASSES_ROOT\.htm HKEY_CLASSES_ROOT\.html HKEY_CLASSES_ROOT\http\shell\open\command HKEY_CLASSES_ROOT\http\shell\open\ddeexec\Application HKEY_CLASSES_ROOT\https\shell\open\command HKEY_CLASSES_ROOT\https\shell\open\ddeexec\Application HKEY_CLASSES_ROOT\htmlfile\shell\open\command HKEY_CLASSES_ROOT\Microsoft.Website\Shell\Open\Command Edit1: I've found two potential solutions but I won't be able to try them until tomorrow. One is to disable the "Windows Font Cache" service. Another is to clear IE cache and browsing history. I won't be able to try out either solution until tomorrow since this is a remote client's machine. I see there are lots of other suggestions online but if you take the time to read them through you'll see that the other suggestions didn't fix the problem.

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• How to find the process(es) which are hogging the machine

  - by Aaron Digulla

  Scenario: All of a sudden, my computer feels sluggish. Mouse moves but windows take ages to open, etc. uptime says the load is 7.69 and raising. What is the fastest way to find out which process(es) are the cause of the load? Now, "top" and similar tools isn't the answer because they either show CPU or memory usage but not both at the same time. What I need is the single command which I might be able to type as it happens - something that will figure out any of System is trying to swap 8GB of RAM to disk because process X ... or process X seeks all over the disk or process X uses 400% CPU" So what I'm looking for is iostat, htop/atop and similar tools run into one with an output like this: 1235 cp - Disk trashing 87 chrome - Uses 2&nbsp;GB of RAM 137 nfs_bench - Uses 95% of the network bandwidth I don't want a tool that gives me some numbers which I can analyze but a tool that tells me exactly which process causes the current load. Assume that the user in front of the keyboard barely knows how to write "process", but the user is quickly overwhelmed when it comes to "resident size", "virtual memory" or "process life cycle". My argument goes like this: A user notices a problem. There can be thousands of reasons ... well, almost :-) The user wants to know the source of the problem. The current solutions give me lots of numbers, and I need to know what these numbers mean. What I'm looking for is a meta tool. 99% of the data is irrelevant to the problem. So what the tool should do is look for processes which hog some resource and list only those along with "this process needs a lot of CPU, this produces many IRQs, this process allocates a lot of RAM (and it's still growing)". This will be a relatively short list. It will be much more simple for someone new to this to locate the culprit from this list than from the output of, say, htop which gives me about 5000 numbers but requires me to fold multi-threaded processes myself (I have 50 lines which say VIRT 2750M but only 16 GB of RAM - the machine ought to swap itself to death but of course, this is a misinterpretation of the data that can happen quickly).

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• Can't install .NET framework 4.0 on Windows XP professional version 2002 SP3 (OS bug?)

  - by that guy

  .NET framework 4.0 install fails on Windows XP professional version 2002 SP3: I tried to run setup using "run as..." to make sure the admin rights are used ("protect my computer..." tick was deselected of course). I tried everything: installing using online/offline setup, windows update. install goes a little and then "rolls back" and says: Installation did not succeed .NET Framework 4 has not been installed because: Fatal error during installation. for more information about this problem, see the log file. the full log: http://pastebay.net/1433771 Any ideas? EDIT1: I have found this in the log: "BlockIf: You must install the 32-bit Windows Imaging Component (WIC) before you run Setup. Please visit the Microsoft Download Center to install WIC, and then rerun Setup...." So I found it, and launched "wic_x86_enu.exe" - but it said: WIC Setup error Newer version of update is already on the system. I have already installed: .NET framewrok 2.0 SP2 .NET framewrok 3.0 SP2 .NET framewrok 3.5 SP1 but I need 4.0 . EDIT2: another attempt and it's log. (this time better copy of log file): http://pastebin.com/gmGfbM9a (copy to notepad and save as .htm and open with internet browser). I have tried all the solutions I could find - and nothing helped. I have found something weird: when I formatted the hard drive and installed windows xp again - the .NET framework 4.0 installed ok, but when I plugged my 100Mbit internet cable - the operating system kind off "locked itself" and the bug returned - I could no longer install .NET framework 4.0 again. There was no reason for that to happen, for example I have windows server 2003 in local network, but I don't have active directory enabled on it or anything like that - the server just has some folders shared and thats all (all server's "features" are default). I had the second pc with the same problem - with XP on it too. This seems like the bug of Operating System to me. I couldn't find what was causing the problem. After many days I gave up: backuped everything, formatted HDD and installed Windows 7 professional 64bit. .NET framework 4.0 installed with no problem on it.

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• How to run a restricted set of programs with Administrator privileges without giving up Admin acces (Win7 Pro)

  - by frLich

  I have a shared system, running Windows7 X64, restricted to a 'standard user' with no password. Not everyone who has access to the system has the administrator password. This works rather well, except for some applications - specially the unlock-applications for encrypted hard drives/USB flash drives. The specific ones either require Administrator access (eg. Seagate Blackarmor) or simply fail without it -- since these programs are sending raw commands to a device, this is to be expected. I would like to be able to add the hashes of these particular programs to a whitelist, and have them run as administrator without needing any prompts. Since these are by definition on removable media, I can't simply use a filename or even a path. One of the users who shares the system can be considered 'crafty', so anything which temporarily grants administrator rights to an user account is certain to cause problems. What i'd like to be able to do: 1) Create an admin account that can only run programs from a whitelist (or, failing that, from a directory) I can't find a good way to do this: As far as I can tell, SRP applies equally to ALL users? Even if I put a "Deny" token on all directories on the system, such that new directories would inherit it, it could still potentially run things from the mounted USB devices. I also don't know whether it's possible to create a new directory that DOESN'T inherit from the parent, that would lake the deny token, and provide admin access. 2) Find a lightweight service that will run these programs in its local context Windows7 seems to block cross-privilege level communication by default, and I haven't found such for windows 7. One example seems to be "sudo" (http://pages.cpsc.ucalgary.ca/~nfriess/sudo/) but because it uses a WLNOTIFY hook, it won't work under Vista nor Windows7 Non-Solutions: - RunAs: Requires administrator password! (but everyone calls it "sudo" anyway) - RunAs /savecred: Nice idea, but appears to be completely insecure. - RUNASSPC - Same concept as RunAs, uses "encrypted" files with credentials, but checks in user-space. - Scheduled Tasks - "Fixed" permissions make this difficult, and doesn't support interactive processes even if it did. - SuRun: From Google: "Surun uses its own Windows service that adds the user to the group of administrators during program start and removes him automatically from that group again"

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• Incremental RPM package version "numbers" for x.y.z > x.y.z-beta (or alpha, rc, etc)

  - by Jonathan Clarke

  In order to publish RPM packages of several different versions of some software, I'm looking for a way to specify version "numbers" that are considered "upgrades", and include the differentiation of several pre-release versions, such as (in order): "2.4.0 alpha 1", "2.4.0 alpha 2", "2.4.0 alpha 3", "2.4.0 beta 1", "2.4.0 beta 2", "2.4.0 release candidate", "2.4.0 final", "2.4.1", "2.4.2", etc. The main issue I have with this is that RPM considers that "2.4.0" comes earlier than "2.4.0.alpha1", so I can't just add the suffix on the end of the final version number. I could try "2.4.0.alpha1", "2.4.0.beta1", "2.4.0.final", which would work, except for the "release candidate" that would be considered later than "2.4.0.final". An alternative I considered is using the "epoch:" section of the RPM version number (the epoch: prefix is considered before the main version number so that "1:2.4.0" is actually earlier than "2:1.0.0"). By putting a timestamp in the epoch: field, all the versions get ordered as expected by RPM, because their versions appear to increment in time. However, this fails when new releases are made on several major versions at the same time (for example, 2.3.2 is released after 2.4.0, but their version for RPM are "20121003:2.3.2" and "20120928:2.4.0" and systems on 2.3.2 can't get "upgraded" to 2.4.0, because rpm sees it as an older version). In this case, yum/zypper/etc refuse to upgrade to 2.4.0, thus my problem. What version numbers can I use to achieve this, and make sure that RPM always considers the version numbers to be in order. Or if not version numbers, other mechanism in RPM packaging? Note 1: I would like to keep the "Release:" field of the spec file for it's original purpose (several releases of packages, including packaging changes, for the same version of the packaged software). Note 2: This should work on current production versions of major distributions, such as RHEL/CentOS 6 and SLES 11. But I'm interested in solutions that don't, too, so long as they don't involve recompiling rpm! Note 3: On Debian-like systems, dpkg uses a special component in the version number which is the "~" (tilde) character. This causes dpkg to count the suffix as "negative" ordering, so that "2.4.0~anything" will come before "2.4.0". Then, normal ordering applies after the "~", so "2.4.0~alpha1" comes before "2.4.0~beta1" because "alpha" comes before "beta" alphabetically. I'm not necessarily looking to use the same scheme for RPM packages (I'm pretty sure no such equivalent exists), so this is just FYI.

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• Configure server on network to analyze traffic

  - by Strajan Sebastian

  I have the following network: http://i.stack.imgur.com/rapkH.jpg I want to send all the traffic from the devices that connect to the 192.168.0.1 router to the 192.168.10.1 router(and eventually to the Internet), by passing through the server and an additional router. Almost 2 days have passed and I can't figure what is wrong. While searching on the Internet for some similar configuration I found some articles that are somehow related to my needs, but the proposed solutions don't seem to work for me. This is a similar article: iptables forwarding between two interface I done the following steps for the configuration process: Set static IP address 192.168.1.90 for the eth0 on the server from the 192.168.1.1 router Set static IP address 192.168.0.90 for the eth1 on the server from the 192.168.0.1 router Forwarded all the traffic from 192.168.0.1 router to the server on eth1 interface witch seems to be working. The router firmware has some option to redirect all the traffic from all the ports to a specified address. Added the following rules on the server(Only the following, there aren't any additional rules): iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE iptables -A FORWARD -i eth1 -o eth0 -m state -–state RELATED,ESTABLISHED -j ACCEPT iptables -A FORWARD -i eth0 -o eth1 -j ACCEPT I also tried changing iptables -A FORWARD -i eth1 -o eth0 -m state -–state RELATED,ESTABLISHED -j ACCEPT into iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT but still is not working. After adding the following to enable the packet forwarding for the server that is running CentOS: echo 1 /proc/sys/net/ipv4/ip_forward sysctl -w net.ipv4.ip_forward = 1 After a server restart and extra an extra check to see that all the configuration from above are still available I tried to see again if I can ping from a computer connected to 192.168.0.1/24 LAN the router from 192.168.1.1 but it didn't worked. The server has tshark(console wireshark) installed and I found that while sending a ping from a computer connected to 192.168.0.1 router to 192.168.1.1 the 192.168.0.90(eth1) receives the ping but it doesn't forward it to the eth0 interface as the rule tells: iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT and don't now why this is happening. Questions: The iptables seem that don't work as I am expecting. Is there a need to add in the NAT table from iptables rules to redirect the traffic to the proper location, or is something else wrong with what I've done? I want to use tshark to view the traffic on the server because I think that is the best at doing this. Do you know something better that tshark to capture the traffic and maybe analyze it?

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• A Windows Update Prevented Live Discs From Working?

  - by user88311

  First off I'll state my system specs. Acer Aspire M1100 Windows Vista Home Basic 32bit OEM 2 Gigs of DDR2 ram 160Gig hard drive 2.7Ghz AMD Athlon 64 processor ATI Radeon X1250 Graphics card A few days ago my computer did automatic updates and updated windows defender to KB915597 (Definition 1.135.415.0), After which when shutting down and starting up I would receive BSOD with the information BUGCODE_USE_DRIVER and 0x000000FE (0x00000008, 0x00000006, 0x00000006, 0x877330000) upon where my computer would not start up with any USB devices plugged in and it always require me to run startup repair before it started. Upon when I first started it up and was able to fully boot windows, I had no use of the mouse so I was unable to install the fix that the windows solutions center brought up on my screen, so I restarted again and installed the fix hoping it would cease the problem, it did not. Upoon starting up after installing the fix and restarting I was confronted with the BSOD 0x000000FE (0x00000008, 0x00000006, 0x00000006, 0x83291000) at which I found the startup repair could not fix the problem and I restored, as I most like should have in the first place. After going through that I read that simply installing the latest defender version from the microsoft site had fixed this problem for others, so I did that, to find I still received the BSOD's. So in a attempt to find a fix to the problem I went to the microsoft answers site to try to find a way to fix the problem, there I was told to simply disable defender and reboot to see if that fixed the problem, upon doing this my computer would no longer even startup, when I boot normally I get to just when the loading screen finishes and then my computer restarts and when I run startup repair, it runs for about 15 seconds and then my computer restarts as well. I have tried running ubuntu live discs in order to simply access the drive and simply copy and paste the 2 month old physical backup I have of my C drive to the C drive, but whenever I run the live OS when it gets to the end of the load screen and is about to boot, the computer again restarts, yet if I put in a gparted disc, I am able to boot it fully, although it does not give me access to the file system just partition managing and when I attempt to access the internet through it, the computer once again restarts. So my question is, how could the update and what has happened prevent me from running the live OS's properly?

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• Need a script/batch/program that runs a command that won't be killed when the parent is killed

  - by billc.cn

  The scenario I use Zabbix to monitor my servers and recently I wanted to add some more metrics for the Windows ones. For security reasons, I used Zabbix's User Parameter feature, but it limits the execution of external commands to about 3 seconds. After that, the command is forcibly killed. I want to run some long run commands, so I used the trick from Zabbix's forum: run the command in the background, write the results to a file and use Zabbix to collect them. This is rather easy under *nix thanks to the "&" operator, but there is no such support in Windows' shell. To make things worse, when Zabbix kills forcibly kill the cmd.exe it used to evaluate the commands, all child processes die including the unfinished background tasks. Thus I need something that can sever all the ties with its children so they won't be affected in the cascading kill. What I've tried start and start /B - They do nothing as the child always die with the parent WScript.Shell.Run as in invis.vbs from StackOverflow - Sometimes work. If the wscript process is forcibly killed as opposed to quitting on its own, the children will die as well. hstart - similar results to invis.vbs At command - This requires you to set an absolution time for the task to run as opposed to an offset, so the code would be quite messy due to the limited shell scripting capability of Windows. (Edit) PsExec.exe from the SysInternals suite - It uses a service to launch the command, so it is not affected by the kill; however, it prints some banner and log info to StdErr and there's no switch to disable this. When I use 2>NUL to redirect them, Zabbix reports an error. After trying the above in different combinations, I noticed if I call hstart from invis.vbs, the command started by the former will be left alone as a parent-less process when invis.vbs is killed. However, since I need to redirect the output, the command I want to run is always in the form of cmd.exe /c ""command" "args"" >log. The vbs also removes all the quotes, so I have to encode the command with self-defined escape sequences. The end result involves about five levels of escaping/quoting, which is almost impossible to maintain. Anyone know any better solutions? Some requirements Any bat/vbs/js/Win32 binary is acceptable Better not require multiple levels of escaping No .Net (including PowerShell) because it is not installed

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• 2 servers, high availability and faster response

  - by user17886

  I recently bought a second webserver because I worry about hardware failure of my old server. Now that I have that second server I wish to do a little more then just have one server standby and replicate all day. As long as it's there I might as well get some advantage our of it ! I have a website powered by ubuntu 12.04, nginx, php-fpm, apc, mysql (5.5) and couchdb. Im currently testing configurations where i can achieve failover AND make good use of the extra harware for faster responses / distributed load. The setup I am testing nowinvolves heartbeat for ip failover and two identical servers. Of the two servers only one has a public ip adress. If one server crashes the other server takes over the public ip adress. On an incoming request nginx forwards the request tot php-fpm to either server a of server b (50/50 if both servers are alive). Once the request has been send to php-fpm both servers look at localhost for the mysql server. I use master-master mysql replication for this. The file system is synced with lsyncd. This works pretty well but Im reading it's discouraged by the (mysql) community. Another option I could think of is to use one server as a mysql master and one server as a web/php server. The servers would still sync their filesystem, would still run the same duplicate software (nginx,mysql) but master slave mysql replication could be used. As long as bother servers are alive I could just prefer nginx to listen to ip a and mysql to ip b. If one server is down, the other server could take over the task of the other server, simply by ip switching. But im completely new at this so I would greatly value your expert advice. Is either of the two setups any good ? If you have any thoughts on this please let me know ! PS, virtualisation, hosting on different locations or active/passive setups are not solutions im looking for. I find virtual server either too slow or too expensive. I already have a passive failover on another location. But in case of a crash I found the site was still unreachable for too long due to dns caching.

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• How to troubleshoot port forwarding on Windows 7 (64 Bit) with ICS enabled?

  - by LearnCocos2D

  I want to forward some ports (1666 for perforce, 8081 for Hudson) on my Internet Gateway machine. This machine is running Windows 7 (64 Bit, legal, user-account) and connected to the Internet via cable modem (it's not a router). The Windows machine is sharing its Internet Connection via ICS and that works fine on all connected computers. I can access the services via the gateway's public IP (95.x.x.x) on the given ports if they are running on the gateway machine itself. I've added the ports and destination IP address (192.168.0.18) in the Internet network adapter's Advanced Settings dialog (Sharing tab). That's the same dialog where you have a list of preconfigured services like HTTP, FTP and other incoming services. When I do that I can't connect to the services anymore. For some reason port forwarding isn't working. I have uninstalled Bitdefender because I wanted to check if the Firewall interferes. I've also disabled the Windows Firewall and Defender to no avail. I tried a freeware tool that helps to setup port forwarding but that didn't work either. The target machine is a Mac OS X computer whose Firewall is disabled. The IP is static. I can successfully connect to the services using the local IP address (192.168.0.18) from two different machines, including the gateway computer. So internally and externally it seems to me that the ports are open and not blocked, and the issue is with port forwarding itself. From what I understand it should be enough to add an entry to the Advanced Settings dialog to enable port forwarding when there are no firewalls interfering. How can I troubleshoot why port forwarding isn't working for me? What steps should I follow to alleviate the issue? PS: I gladly accept command line solutions. Other things I've tried: adding an Inbound Rule to Windows Firewall for the 1666, 8081 ports trying with Windows Firewall enabled and disabled disabling/enabling the network adapter double-checked that the IP addresses are correct mapping a different incoming port to the service's actual port followed or checked the misc tips in this article What I haven't dared trying yet (let me know if it's worth a shot): disable/enable ICS remove all network adapters (via Control Panel), then re-install and re-configure them

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• Internet Pings but Does Not Load

  - by t3techcom18

  From what I've been seeing and been doing my research for the past two days, many people have been having the same issues throughout the years, however, this is the first time I've encountered this issue and many of the specific workarounds or fixes have not worked for me. I've been trying to work through this for 24 hours straight now, but to no avail so many thanks to those that can help. On Monday night, got home from work; surfing the internet for half an hour, everything was fine as always. Just after half an hour, my Internet got very sluggish and then it died completely. I thought it might have been the an update I just put through in terms of Windows Update that said was a critical update for MSE, as the same thing happened a few years ago. I did a System Restore to two different dates that were in the past two weeks, nothing. Uninstalled MSE and disabled Windows Defender and the Windows Firewall: Nothing. Reset IE Options, Reset Winsock, Dumping DNS, many of the other command prompt screens to reset items: Nothing. Reset the modem: Nothing. What DID work, however, was a ping test to Yahoo. The ping test worked, saying all four packets was recieved, yet nothing else popped up. LAN and CenturyLink said everything worked on their end and that everything was connected properly, as well as the speeds working fine. CenturyLink said in their notes that they thought Port 80 was blocked. I went and put in the Firewall to allow Port 80 but it didn't make any difference whatsoever. I remembered I had a spare modem laying around and I switched them up, both modem and the cords - nothing. I then hooked it up to my netbook to see if that would work, as it usually does - connection didn't work there either. Like I said, it's been about 24 hours now and this is increasingly frustrating, as I've tried all solutions (While browsing through 10 search results pages on my phone) suggested and still nothing. Any suggestions and tricks would be greatly appreciated! Here's my specs: Windows 7 32-bit Home Premium Intel Core 2 Duo 3.14 Ghz 4 GB Kingston DDR2 RAM eVGA nForce 750i SLI eVGA GeForce GTX 560 Ti FPB ISP: CenturyLink No router Modem: CenturyLink 660 Series Hardwired connection PLEASE NOTE: This is the only computer I have (Like I said, the netbook solution didn't work), so downloading programs and such is not an option til I get to other computers somewhere else, like right now. Unless someone knows of a way of copying/pasting a file in Windows and then transferring said info to an Android smartphone, this is gunna take a while haha. Patience is requested.

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• Why is my unsafe code block slower than my safe code?

  - by jomtois

  I am attempting to write some code that will expediently process video frames. I am receiving the frames as a System.Windows.Media.Imaging.WriteableBitmap. For testing purposes, I am just applying a simple threshold filter that will process a BGRA format image and assign each pixel to either be black or white based on the average of the BGR pixels. Here is my "Safe" version: public static void ApplyFilter(WriteableBitmap Bitmap, byte Threshold) { // Let's just make this work for this format if (Bitmap.Format != PixelFormats.Bgr24 && Bitmap.Format != PixelFormats.Bgr32) { return; } // Calculate the number of bytes per pixel (should be 4 for this format). var bytesPerPixel = (Bitmap.Format.BitsPerPixel + 7) / 8; // Stride is bytes per pixel times the number of pixels. // Stride is the byte width of a single rectangle row. var stride = Bitmap.PixelWidth * bytesPerPixel; // Create a byte array for a the entire size of bitmap. var arraySize = stride * Bitmap.PixelHeight; var pixelArray = new byte[arraySize]; // Copy all pixels into the array Bitmap.CopyPixels(pixelArray, stride, 0); // Loop through array and change pixels to black or white based on threshold for (int i = 0; i < pixelArray.Length; i += bytesPerPixel) { // i=B, i+1=G, i+2=R, i+3=A var brightness = (byte)((pixelArray[i] + pixelArray[i + 1] + pixelArray[i + 2]) / 3); var toColor = byte.MinValue; // Black if (brightness >= Threshold) { toColor = byte.MaxValue; // White } pixelArray[i] = toColor; pixelArray[i + 1] = toColor; pixelArray[i + 2] = toColor; } Bitmap.WritePixels(new Int32Rect(0, 0, Bitmap.PixelWidth, Bitmap.PixelHeight), pixelArray, stride, 0); } Here is what I think is a direct translation using an unsafe code block and the WriteableBitmap Back Buffer instead of the forebuffer: public static void ApplyFilterUnsafe(WriteableBitmap Bitmap, byte Threshold) { // Let's just make this work for this format if (Bitmap.Format != PixelFormats.Bgr24 && Bitmap.Format != PixelFormats.Bgr32) { return; } var bytesPerPixel = (Bitmap.Format.BitsPerPixel + 7) / 8; Bitmap.Lock(); unsafe { // Get a pointer to the back buffer. byte* pBackBuffer = (byte*)Bitmap.BackBuffer; for (int i = 0; i < Bitmap.BackBufferStride*Bitmap.PixelHeight; i+= bytesPerPixel) { var pCopy = pBackBuffer; var brightness = (byte)((*pBackBuffer + *pBackBuffer++ + *pBackBuffer++) / 3); pBackBuffer++; var toColor = brightness >= Threshold ? byte.MaxValue : byte.MinValue; *pCopy = toColor; *++pCopy = toColor; *++pCopy = toColor; } } // Bitmap.AddDirtyRect(new Int32Rect(0,0, Bitmap.PixelWidth, Bitmap.PixelHeight)); Bitmap.Unlock(); } This is my first foray into unsafe code blocks and pointers, so maybe the logic is not optimal. I have tested both blocks of code on the same WriteableBitmaps using: var threshold = Convert.ToByte(op.Result); var copy2 = copyFrame.Clone(); Stopwatch stopWatch = new Stopwatch(); stopWatch.Start(); BinaryFilter.ApplyFilterUnsafe(copyFrame, threshold); stopWatch.Stop(); var unsafesecs = stopWatch.ElapsedMilliseconds; stopWatch.Reset(); stopWatch.Start(); BinaryFilter.ApplyFilter(copy2, threshold); stopWatch.Stop(); Debug.WriteLine(string.Format("Unsafe: {1}, Safe: {0}", stopWatch.ElapsedMilliseconds, unsafesecs)); So I am analyzing the same image. A test run of an incoming stream of video frames: Unsafe: 110, Safe: 53 Unsafe: 136, Safe: 42 Unsafe: 106, Safe: 36 Unsafe: 95, Safe: 43 Unsafe: 98, Safe: 41 Unsafe: 88, Safe: 36 Unsafe: 129, Safe: 65 Unsafe: 100, Safe: 47 Unsafe: 112, Safe: 50 Unsafe: 91, Safe: 33 Unsafe: 118, Safe: 42 Unsafe: 103, Safe: 80 Unsafe: 104, Safe: 34 Unsafe: 101, Safe: 36 Unsafe: 154, Safe: 83 Unsafe: 134, Safe: 46 Unsafe: 113, Safe: 76 Unsafe: 117, Safe: 57 Unsafe: 90, Safe: 41 Unsafe: 156, Safe: 35 Why is my unsafe version always slower? Is it due to using the back buffer? Or am I doing something wrong? Thanks

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• How to get rid of previous reflection when reflecting a UIImageView (with changing pictures)?

  - by epale

  Hi everyone, I have managed to use the reflection sample app from apple to create a reflection from a UIImageView. But the problem is that when I change the picture inside the UIImageView, the reflection from the previous displayed picture remains on the screen. The new reflection on the next picture then overlaps the previous reflection. How do I ensure that the previous reflection is removed when I change to the next picture? Thank you so much. I hope my question is not too basic. Here is the codes which i used so far: //reflection self.view.autoresizesSubviews = YES; self.view.userInteractionEnabled = YES; // create the reflection view CGRect reflectionRect = currentView.frame; // the reflection is a fraction of the size of the view being reflected reflectionRect.size.height = reflectionRect.size.height * kDefaultReflectionFraction; // and is offset to be at the bottom of the view being reflected reflectionRect = CGRectOffset(reflectionRect, 0, currentView.frame.size.height); reflectionView = [[UIImageView alloc] initWithFrame:reflectionRect]; // determine the size of the reflection to create NSUInteger reflectionHeight = currentView.bounds.size.height * kDefaultReflectionFraction; // create the reflection image, assign it to the UIImageView and add the image view to the containerView reflectionView.image = [self reflectedImage:currentView withHeight:reflectionHeight]; reflectionView.alpha = kDefaultReflectionOpacity; [self.view addSubview:reflectionView]; //reflection */ Then the codes below are used to form the reflection: CGImageRef CreateGradientImage(int pixelsWide, int pixelsHigh) { CGImageRef theCGImage = NULL; // gradient is always black-white and the mask must be in the gray colorspace CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray(); // create the bitmap context CGContextRef gradientBitmapContext = CGBitmapContextCreate(nil, pixelsWide, pixelsHigh, 8, 0, colorSpace, kCGImageAlphaNone); // define the start and end grayscale values (with the alpha, even though // our bitmap context doesn't support alpha the gradient requires it) CGFloat colors[] = {0.0, 1.0, 1.0, 1.0}; // create the CGGradient and then release the gray color space CGGradientRef grayScaleGradient = CGGradientCreateWithColorComponents(colorSpace, colors, NULL, 2); CGColorSpaceRelease(colorSpace); // create the start and end points for the gradient vector (straight down) CGPoint gradientStartPoint = CGPointZero; CGPoint gradientEndPoint = CGPointMake(0, pixelsHigh); // draw the gradient into the gray bitmap context CGContextDrawLinearGradient(gradientBitmapContext, grayScaleGradient, gradientStartPoint, gradientEndPoint, kCGGradientDrawsAfterEndLocation); CGGradientRelease(grayScaleGradient); // convert the context into a CGImageRef and release the context theCGImage = CGBitmapContextCreateImage(gradientBitmapContext); CGContextRelease(gradientBitmapContext); // return the imageref containing the gradient return theCGImage; } CGContextRef MyCreateBitmapContext(int pixelsWide, int pixelsHigh) { CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); // create the bitmap context CGContextRef bitmapContext = CGBitmapContextCreate (nil, pixelsWide, pixelsHigh, 8, 0, colorSpace, // this will give us an optimal BGRA format for the device: (kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst)); CGColorSpaceRelease(colorSpace); return bitmapContext; } (UIImage *)reflectedImage:(UIImageView *)fromImage withHeight:(NSUInteger)height { if (!height) return nil; // create a bitmap graphics context the size of the image CGContextRef mainViewContentContext = MyCreateBitmapContext(fromImage.bounds.size.width, height); // offset the context - // This is necessary because, by default, the layer created by a view for caching its content is flipped. // But when you actually access the layer content and have it rendered it is inverted. Since we're only creating // a context the size of our reflection view (a fraction of the size of the main view) we have to translate the // context the delta in size, and render it. // CGFloat translateVertical= fromImage.bounds.size.height - height; CGContextTranslateCTM(mainViewContentContext, 0, -translateVertical); // render the layer into the bitmap context CALayer *layer = fromImage.layer; [layer renderInContext:mainViewContentContext]; // create CGImageRef of the main view bitmap content, and then release that bitmap context CGImageRef mainViewContentBitmapContext = CGBitmapContextCreateImage(mainViewContentContext); CGContextRelease(mainViewContentContext); // create a 2 bit CGImage containing a gradient that will be used for masking the // main view content to create the 'fade' of the reflection. The CGImageCreateWithMask // function will stretch the bitmap image as required, so we can create a 1 pixel wide gradient CGImageRef gradientMaskImage = CreateGradientImage(1, height); // create an image by masking the bitmap of the mainView content with the gradient view // then release the pre-masked content bitmap and the gradient bitmap CGImageRef reflectionImage = CGImageCreateWithMask(mainViewContentBitmapContext, gradientMaskImage); CGImageRelease(mainViewContentBitmapContext); CGImageRelease(gradientMaskImage); // convert the finished reflection image to a UIImage UIImage *theImage = [UIImage imageWithCGImage:reflectionImage]; // image is retained by the property setting above, so we can release the original CGImageRelease(reflectionImage); return theImage; } */

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• Techniques for modeling a dynamic dataflow with Java concurrency API

  - by Maian

  Is there an elegant way to model a dynamic dataflow in Java? By dataflow, I mean there are various types of tasks, and these tasks can be "connected" arbitrarily, such that when a task finishes, successor tasks are executed in parallel using the finished tasks output as input, or when multiple tasks finish, their output is aggregated in a successor task (see flow-based programming). By dynamic, I mean that the type and number of successors tasks when a task finishes depends on the output of that finished task, so for example, task A may spawn task B if it has a certain output, but may spawn task C if has a different output. Another way of putting it is that each task (or set of tasks) is responsible for determining what the next tasks are. Sample dataflow for rendering a webpage: I have as task types: file downloader, HTML/CSS renderer, HTML parser/DOM builder, image renderer, JavaScript parser, JavaScript interpreter. File downloader task for HTML file HTML parser/DOM builder task File downloader task for each embedded file/link If image, image renderer If external JavaScript, JavaScript parser JavaScript interpreter Otherwise, just store in some var/field in HTML parser task JavaScript parser for each embedded script JavaScript interpreter Wait for above tasks to finish, then HTML/CSS renderer (obviously not optimal or perfectly correct, but this is simple) I'm not saying the solution needs to be some comprehensive framework (in fact, the closer to the JDK API, the better), and I absolutely don't want something as heavyweight is say Spring Web Flow or some declarative markup or other DSL. To be more specific, I'm trying to think of a good way to model this in Java with Callables, Executors, ExecutorCompletionServices, and perhaps various synchronizer classes (like Semaphore or CountDownLatch). There are a couple use cases and requirements: Don't make any assumptions on what executor(s) the tasks will run on. In fact, to simplify, just assume there's only one executor. It can be a fixed thread pool executor, so a naive implementation can result in deadlocks (e.g. imagine a task that submits another task and then blocks until that subtask is finished, and now imagine several of these tasks using up all the threads). To simplify, assume that the data is not streamed between tasks (task output-succeeding task input) - the finishing task and succeeding task won't exist together, so the input data to the succeeding task will not be changed by the preceeding task (since it's already done). There are only a couple operations that the dataflow "engine" should be able to handle: A mechanism where a task can queue more tasks A mechanism whereby a successor task is not queued until all the required input tasks are finished A mechanism whereby the main thread (or other threads not managed by the executor) blocks until the flow is finished A mechanism whereby the main thread (or other threads not managed by the executor) blocks until certain tasks have finished Since the dataflow is dynamic (depends on input/state of the task), the activation of these mechanisms should occur within the task code, e.g. the code in a Callable is itself responsible for queueing more Callables. The dataflow "internals" should not be exposed to the tasks (Callables) themselves - only the operations listed above should be available to the task. Note that the type of the data is not necessarily the same for all tasks, e.g. a file download task may accept a File as input but will output a String. If a task throws an uncaught exception (indicating some fatal error requiring all dataflow processing to stop), it must propagate up to the thread that initiated the dataflow as quickly as possible and cancel all tasks (or something fancier like a fatal error handler). Tasks should be launched as soon as possible. This along with the previous requirement should preclude simple Future polling + Thread.sleep(). As a bonus, I would like to dataflow engine itself to perform some action (like logging) every time task is finished or when no has finished in X time since last task has finished. Something like: ExecutorCompletionService<T> ecs; while (hasTasks()) { Future<T> future = ecs.poll(1 minute); some_action_like_logging(); if (future != null) { future.get() ... } ... } Are there straightforward ways to do all this with Java concurrency API? Or if it's going to complex no matter what with what's available in the JDK, is there a lightweight library that satisfies the requirements? I already have a partial solution that fits my particular use case (it cheats in a way, since I'm using two executors, and just so you know, it's not related at all to the web browser example I gave above), but I'd like to see a more general purpose and elegant solution.

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• New hire expectations... (Am I being unreasonable?)

  - by user295841

  I work for a very small custom software shop. We currently consist me and my boss. My boss is an old FoxPro DOS developer and OOP makes him uncomfortable. He is planning on taking a back seat in the next few years to hopefully enjoy a “partial retirement”. I will be taking over the day to day operations and we are now desperately looking for more help. We tried Monster.com, Dice.com, and others a few years ago when we started our search. We had no success. We have tried outsourcing overseas (total disaster), hiring kids right out of college (mostly a disaster but that’s where I came from), interns (good for them, not so good for us) and hiring laid off “experienced” developers (there was a reason they were laid off). I have heard hiring practices discussed on podcasts, blogs, etc... and have tried a few. The “Fizz Buzz” test was a good one. One kid looked physically ill before he finally gave up. I think my problem is that I have grown so much as a developer since I started here that I now have a high standard. I hear/read very intelligent people podcasts and blogs and I know that there are lots of people out there that can do the job. I don’t want to settle for less than a “good” developer. Perhaps my expectations are unreasonable. I expect any good developer (entry level or experienced) to be billable (at least paying their own wage) in under one month. I expect any good developer to be able to be productive (at least dangerous) in any language or technology with only a few days of research/training. I expect any good developer to be able to take a project from initial customer request to completion with little or no help from others. Am I being unreasonable? What constitutes a valuable developer? What should be expected of an entry level developer? What should be expected of an experienced developer? I realize that everyone is different but there has to be some sort of expectations standard, right? I have been giving the test project below to potential canidates to weed them out. Good idea? Too much? Too little? Please let me know what you think. Thanks. Project ID: T00001 Description: Order Entry System Deadline: 1 Week Scope The scope of this project is to develop a fully function order entry system. Screen/Form design must be user friendly and promote efficient data entry and modification. User experience (Navigation, Screen/Form layouts, Look and Feel…) is at the developer’s discretion. System may be developed using any technologies that conform to the technical and system requirements. Deliverables Complete source code Database setup instructions (Scripts or restorable backup) Application installation instructions (Installer or installation procedure) Any necessary documentation Technical Requirements Server Platform – Windows XP / Windows Server 2003 / SBS Client Platform – Windows XP Web Browser (If applicable) – IE 8 Database – At developer’s discretion (Must be a relational SQL database.) Language – At developer’s discretion All data must be normalized. (+) All data must maintain referential integrity. (++) All data must be indexed for optimal performance. System must handle concurrency. System Requirements Customer Maintenance Customer records must have unique ID. Customer data will include Name, Address, Phone, etc. User must be able to perform all CRUD (Create, Read, Update, and Delete) operations on the Customer table. User must be able to enter a specific Customer ID to edit. User must be able to pull up a sortable/queryable search grid/utility to find a customer to edit. Validation must be performed prior to database commit. Customer record cannot be deleted if the customer has an order in the system. (++) Inventory Maintenance Part records must have unique ID. Part data will include Description, Price, UOM (Unit of Measure), etc. User must be able to perform all CRUD operations on the part table. User must be able to enter a specific Part ID to edit. User must be able to pull up a sortable/queryable search grid/utility to find a part to edit. Validation must be performed prior to database commit. Part record cannot be deleted if the part has been used in an order. (++) Order Entry Order records must have a unique auto-incrementing key (Order Number). Order data must be split into a header/detail structure. (+) Order can contain an infinite number of detail records. Order header data will include Order Number, Customer ID (++), Order Date, Order Status (Open/Closed), etc. Order detail data will include Part Number (++), Quantity, Price, etc. User must be able to perform all CRUD operations on the order tables. User must be able to enter a specific Order Number to edit. User must be able to pull up a sortable/queryable search grid/utility to find an order to edit. User must be able to print an order form from within the order entry form. Validation must be performed prior to database commit. Reports Customer Listing – All Customers in the system. Inventory Listing – All parts in the system. Open Order Listing – All open orders in system. Customer Order Listing – All orders for specific customer. All reports must include sorts and filter functions where applicable. Ex. Customer Listing by range of Customer IDs. Open Order Listing by date range.

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• Find the set of largest contiguous rectangles to cover multiple areas

  - by joelpt

  I'm working on a tool called Quickfort for the game Dwarf Fortress. Quickfort turns spreadsheets in csv/xls format into a series of commands for Dwarf Fortress to carry out in order to plot a "blueprint" within the game. I am currently trying to optimally solve an area-plotting problem for the 2.0 release of this tool. Consider the following "blueprint" which defines plotting commands for a 2-dimensional grid. Each cell in the grid should either be dug out ("d"), channeled ("c"), or left unplotted ("."). Any number of distinct plotting commands might be present in actual usage. . d . d c c d d d d c c . d d d . c d d d d d c . d . d d c To minimize the number of instructions that need to be sent to Dwarf Fortress, I would like to find the set of largest contiguous rectangles that can be formed to completely cover, or "plot", all of the plottable cells. To be valid, all of a given rectangle's cells must contain the same command. This is a faster approach than Quickfort 1.0 took: plotting every cell individually as a 1x1 rectangle. This video shows the performance difference between the two versions. For the above blueprint, the solution looks like this: . 9 . 0 3 2 8 1 1 1 3 2 . 1 1 1 . 2 7 1 1 1 4 2 . 6 . 5 4 2 Each same-numbered rectangle above denotes a contiguous rectangle. The largest rectangles take precedence over smaller rectangles that could also be formed in their areas. The order of the numbering/rectangles is unimportant. My current approach is iterative. In each iteration, I build a list of the largest rectangles that could be formed from each of the grid's plottable cells by extending in all 4 directions from the cell. After sorting the list largest first, I begin with the largest rectangle found, mark its underlying cells as "plotted", and record the rectangle in a list. Before plotting each rectangle, its underlying cells are checked to ensure they are not yet plotted (overlapping a previous plot). We then start again, finding the largest remaining rectangles that can be formed and plotting them until all cells have been plotted as part of some rectangle. I consider this approach slightly more optimized than a dumb brute-force search, but I am wasting a lot of cycles (re)calculating cells' largest rectangles and checking underlying cells' states. Currently, this rectangle-discovery routine takes the lion's share of the total runtime of the tool, especially for large blueprints. I have sacrificed some accuracy for the sake of speed by only considering rectangles from cells which appear to form a rectangle's corner (determined using some neighboring-cell heuristics which aren't always correct). As a result of this 'optimization', my current code doesn't actually generate the above solution correctly, but it's close enough. More broadly, I consider the goal of largest-rectangles-first to be a "good enough" approach for this application. However I observe that if the goal is instead to find the minimum set (fewest number) of rectangles to completely cover multiple areas, the solution would look like this instead: . 3 . 5 6 8 1 3 4 5 6 8 . 3 4 5 . 8 2 3 4 5 7 8 . 3 . 5 7 8 This second goal actually represents a more optimal solution to the problem, as fewer rectangles usually means fewer commands sent to Dwarf Fortress. However, this approach strikes me as closer to NP-Hard, based on my limited math knowledge. Watch the video if you'd like to better understand the overall strategy; I have not addressed other aspects of Quickfort's process, such as finding the shortest cursor-path that plots all rectangles. Possibly there is a solution to this problem that coherently combines these multiple strategies. Help of any form would be appreciated.

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• Configuring Novel iPrint client on ubuntu 13.10

  - by Mahdi Sadeghi

  Recently I have struggled a lot to make Novel iPrint client to work on my laptop. I need it to use Follow Me printers in our university(you can take your print form any printer). Using this tutorial from Novel, I tried to convert the rpm package and install it on Ubuntu 13.04 & 13.10. The post install script from installing generated deb package had a typo which I saw in post install messages and I fixed that. Now I have the client running. To see the client UI I installed cinnamon desktop(because unity does not have system tray and old solutions did'nt work to whitelist Novel clinet). I have iPrint plugin installed on firefox as well(I copied the shared object files to plugin directories). I try installing printers from provided ipp URL(which lists available printers on the server) with no success. After clicking the printer name I see this: I have various errors: Formerly firefox used to asked my network username/password for installing SSL printer but now it returns this: iPrint Printer - The printer is currently not available. However I can install non-SSL version but the printer location is either empty or points to: file:///dev/null even if I change it to the exact address which I see on working machines still it prints nothing. I have tried the novel command line tool, iprntcmd to print. It is being installed at: /opt/novell/iprint/bin/ msadeghi@werkstatt:/opt/novell/iprint/bin$ ./iprntcmd --addprinter ipp://iprint.rz.hs-offenburg.de/ipp/Follow-me\ -\ IPP iprntcmd v05.04.00 Adding printer ipp://iprint.rz.hs-offenburg.de/ipp/Follow-me - IPP. Added printer ipp://iprint.rz.hs-offenburg.de/ipp/Follow-me - IPP successfully. It adds the printer with empty location and again no print. What I found interesting is the log file at ~/.iprint/errors.txt with strange errors which I hope somebody here can understand. When I try to install the SSL printer I receive these logs(note that HP is my local printer and has nothing to do with iprint): Thu Oct 31 11:02:03 2013 Trace Info: iprint.c, line 6690 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for file:///dev/null - Unknown Port Type - file Thu Oct 31 11:02:03 2013 Trace Info: iprint.c, line 6800 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for hp:/usb/HP_LaserJet_1018?serial=KP103A1 - No Port type specified Thu Oct 31 11:02:05 2013 Trace Info: iprint.c, line 6690 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for file:///dev/null - Unknown Port Type - file Thu Oct 31 11:02:05 2013 Trace Info: iprint.c, line 6800 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for hp:/usb/HP_LaserJet_1018?serial=KP103A1 - No Port type specified Thu Oct 31 11:02:06 2013 Trace Info: mydoreq.c, line 676 Group Info: CLIB Error Code: 0 (0x0) User ID: 1000 Error Msg: Success Debug Msg: MyCupsDoFileRequest - httpReconnect failed (0) Thu Oct 31 11:02:06 2013 Trace Info: mydoreq.c, line 1293 Group Info: CUPS-IPP Error Code: 1282 (0x502) User ID: 1000 Error Msg: iPrint Printer - The printer is currently not available. Debug Msg: MyCupsDoFileRequest - IPP SERVICE UNAVAILABLE Thu Oct 31 11:02:06 2013 Trace Info: iprint.c, line 6690 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for file:///dev/null - Unknown Port Type - file Thu Oct 31 11:02:06 2013 Trace Info: iprint.c, line 6800 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for hp:/usb/HP_LaserJet_1018?serial=KP103A1 - No Port type specified Thu Oct 31 11:02:08 2013 Trace Info: iprint.c, line 6690 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for file:///dev/null - Unknown Port Type - file Thu Oct 31 11:02:08 2013 Trace Info: iprint.c, line 6800 Group Info: IPRINT-lib Error Code: 4096 (0x1000) User ID: 1000 Error Msg: iPrint Lib - Bad URI type supplied (not IPP:, HTTP:, or HTTPS:). Debug Msg: IPRINTInterpretURI for hp:/usb/HP_LaserJet_1018?serial=KP103A1 - No Port type specified I should say that my friend can print using the same instructions on CrunchBang easily and another guy on 12.04 LTS but with more struggling. It worked for me on linux mint maya with my old laptop as well. Is there anybody out there who can help me to solve these problems? I am really disappointed with Novell and our university support. PS. I had the same problemwith 13.04. No matter if I am within the network or I connect with VPN, I have the same issues.

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