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• Does ssh key need to be named id_rsa?

  - by dustyprogrammer

  I have come across this problem a couple of times when creating build servers with keyed authentication. I was wondering if anyone else has experience this. I have a couple of keys for my current user that may connect to different machines. Let say machine1 and machine2. I have pasted my public key into their respective authorized_keys file. The first one I have named the first key id_rsa and the second key bender. When I try to connect to bender I get the following output with my verbose ssh connection debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey debug1: Next authentication method: publickey debug1: Trying private key: /home/bozo/.ssh/.ssh/identity debug1: Trying private key: /home/bozo/.ssh/.ssh/id_rsa debug1: Trying private key: /home/bozo/.ssh/id_dsa debug1: No more authentication methods to try. Permission denied (publickey). It only offers the id_rsa key, as you can see above. Is this correct? If so why? How do I get it to offer more keys? I know it is a problem I see intermittently, because I at home I have multiple keys without much trouble. I would also appreciate a overview on how the pub and private keys interact with the client and server. I thought I had a pretty decent idea, but apparently I am missing something. Please and thank you.

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• Ubuntu security with services running from /opt

  - by thejartender

  It took me a while to understand what's going on here (I think), but can someone explain to me if there are security risks with regards to my logic of what's going on here as I am trying to set up a home web server as a developer with some good Linux knowledge? Ubuntu is not like other systems, as it has restricted the root user account. You can not log in as root or su to root. This was a problem for me as I have had to install numerous applications and services to /opt as per user documentation (XAMPPfor Linux is a good example). The problem here is that this directory is owned by root:root. I notice that my admin user account does not belong to root group through the following command: groups username so my understanding is that even though the files and services that I place in /opt belong to root, executing them by means of sudo (as required) does not mean that they are run as root? I imagine that the sudo command is hidden somewhere under belonging to the root user and has a 775 permission? So the question I have is if running a service like Tomcat, Apcahe, etc exposes my system like on other systems? Obviously I need to secure these in configurations, but isn't the golden rule to never run something as root? What happens if I have multiple services running under same user/group with regards to a compromised server?

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• Help with Rewrite rules.

  - by Kyle

  I was wondering what a rewrite statement that looks for this situation. I want to have multiple users on my server. Each user can have 'VirtualDocumentRoot' like sites in his directory. For example, they just make a directory like 'example.com' in their home directory, and it's hosted. The problem is I don't know if VirtualDocumentRoot can do this, or if it would take a rewrite rule that looks in all the users folders for a domain. Can anybody help me?

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• Iphone/Android app – chatroom development – what framework & hosting needs?

  - by MikaelW

  I have some experience regarding IPhone and Android development but I am now struggling to solve a new class of problem: apps that involve a client/server chatroom feature. That is, an app when people can exchange text over the internet, and without having the app to constantly “pull” content from the server. So that problem can’t be solved with a normal php/mysql website, there must be some kind of application running on a server that is able to send message from the server to the phone, rather than having the phone to check for new messages every 10 seconds… So I’m looking for ways to solve the different problems here: What framework should I use on the two sides (phone / server)? It should be some kind of library that doesn’t prevent me to write paid apps. It should also be possible to have the same server for the Iphone and android version of the app. What server / hosting solution do I need with what sort of features, I just have no experience regarding server application that can handle and initiate multiple connections and are hosted on hardware that is always online I tried to find resources online but couldn’t so far, either the libraries had the wrong kind of license/language or I just didn’t understand… Sometimes there were nice tutorial but for different needs such as peer2peer chat over local network… Same with the server and the hosting problem, not sure where to start really, I’m calling for help and I promise I will complete this page with notes about the experience I will get :-) Obviously the ideal would be to find a tutorial I missed that include client code, server code and a free scalable server… That being said, If I see something as good, it probably means that I have eaten the wrong kind of mushroom again… So, failing that, any pointer which might help me toward that quest, would be greatly appreciated. Thanks in advance. Mikael

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• CodePlex Daily Summary for Wednesday, May 07, 2014

  CodePlex Daily Summary for Wednesday, May 07, 2014Popular ReleasesSeal Report: Seal Report 1.4: New Features: Report Designer: New option to convert a Report Source into a Repository Source. Report Designer: New contextual helper menus to select, remove, copy, prompt elements in a model. Web Server: New option to expand sub-folders displayed in the tree view. Web Server: Web Folder Description File can be a .cshtml file to display a MVC View. Views: additional CSS parameters for some DIVs. NVD3 Chart: Some default configuration values have been changed. Issues Addressed:16 ...Magick.NET: Magick.NET 6.8.9.002: Magick.NET linked with ImageMagick 6.8.9.0.VidCoder: 1.5.22 Beta: Added ability to burn SRT subtitles. Updated to HandBrake SVN 6169. Added checks to prevent VidCoder from running with a database version newer than it expects. Tooltips in the Advanced Video panel now trigger on the field labels as well as the fields themselves. Fixed updating preset/profile/tune/level settings on changing video encoder. This should resolve some problems with QSV encoding. Fixed tunes and profiles getting set to blank when switching between x264 and x265. Fixed co...NuGet: NuGet 2.8.2: We will be releasing a 2.8.2 version of our own NuGet packages and the NuGet.exe command-line tool. The 2.8.2 release will not include updated VS or WebMatrix extensions. NuGet.Server.Extensions.dll needs to be used alongside NuGet-Signed.exe to provide the NuGet.exe mirror functionality.DNN CMS Platform: 07.03.00 BETA (Not For Production Use): DNN 7.3 release is focused on performance and we have made a variety of changes to improve the run-time characteristics of the platform. End users will notice faster page response time and administrators will appreciate a more responsive user experience, especially on larger scale web sites. This is a BETA release and is NOT recommended for production use. There is no upgrade path offered from this release to the final DNN 7.3 release. Known Issues - The Telerik RAD Controls for ASP.NET AJA...babelua: 1.5.3: V1.5.3 - 2014.5.6Stability improvement: support relative path when debugging lua files; improve variable view function in debugger; fix a bug that when a file is loaded at runtime , its breakpoints would not take effect; some other bug fix; New feature: improve tool windows color scheme to look better with different vs themes; comment/uncomment code block easily; some other improve;CTI Text Encryption: CTI Text Encryption 5.0: Improve encryption algorithm. Simplify all-non encryption related mechanism (Simplify user interface)SmartStore.NET - Free ASP.NET MVC Ecommerce Shopping Cart Solution: SmartStore.NET 2.0.2: SmartStore.NET 2.0.2 is primarily a maintenance release for version 2.0.0, which has been released on April 04 2014. It contains several improvements & important fixes. BugfixesIMPORTANT FIX: Memory leak leads to OutOfMemoryException in application after a while Installation fix: some varchar(MAX) columns get created as varchar(4000). Added a migration to fix the column specs. Installation fix: Setup fails with exception Value cannot be null. Parameter name: stream Bugfix for stock iss...Channel9's Absolute Beginner Series: Windows Phone 8.1: Entire source code for Windows Phone 8.1 Absolute Beginner Series.BIDS Helper: BIDS Helper 1.6.6: This BIDS Helper beta release brings support for SQL Server 2014 and SSDTBI for Visual Studio 2013. (Note that SSDTBI for Visual Studio 2013 is currently unavailable to download from Microsoft. We are releasing BIDS Helper support to help those who downloaded it before it became unavailable, and we will recheck BIDS Helper 2014 is compatible after SSDTBI becomes available to download again.) BIDS Helper 2014 Beta Limitations: SQL Server 2014 support for Biml is still in progress, so this bet...Windows Phone IsoStoreSpy (a cool WP8.1 + WP8 Isolated Storage Explorer): IsoStoreSpy WP8.1 3.0.0.0 (Win8 only): 3.0.0.0 + WP8.1 & WP8 device allowed + Local, Roaming or Temp directory Selector for WindowsRuntime apps + Version number in the title :)CS-Script for Notepad++ (C# intellisense and code execution): Release v1.0.24.0: ShortcutMapping panel now allows direct modification of the shortcuts. Custom updater dropped support for MSI installation but it still allows downloading of MSI http://www.csscript.net/npp/codeplex/non_msi_update.pngProDinner - ASP.NET MVC Sample (EF5, N-Tier, jQuery): 8.2: upgrade to mvc 5 upgrade to ASP.net MVC Awesome 4.0, EF 6.1, latest jcrop, Windsor Castle etc. ability to show/hide the dog using tinymce for the feedback page mobile friendly uiASP.net MVC Awesome - jQuery Ajax Helpers: 4.0: version 4.0 ========================== - added InitPopup, InitPopupForm helpers, open initialized popups using awe.open(name, params) - added Tag or Tags for all helpers, usable in mod code - added popup aweclose, aweresize events - popups have api accessible via .data('api'), with methods open, close and destroy - all popups have .awe-popup class - popups can be grouped using .Group(string), only 1 popup in the same group can exist at the same time - added awebeginload event for...SEToolbox: SEToolbox 01.028.008 Release 2: Fixes for drag-drop copying. Added ship joiner, to rejoin a broken ship! Installation of this version will replace older version.ScreenToGif: Release 1.0: What's new: • Small UI tweaks everywhere. • You can add Text, Subtitles and Title Frames. • Processing the gif now takes less time. • Languages: Spanish, Italian and Tamil added. • Single .exe multi language. • Takes less time to apply blur and pixelated efect. • Restart button. • Language picker. (If the user wants to select a diferent language than the system's) • "Encoding Finished" page with a link to open the file. • GreenScreen unchanged pixels to save kilobytes. • "Check for Updates" t...Touchmote: Touchmote 1.0 beta 11: Changes Support for multiple monitor setup Additional settings for analog sticks More reliable pairing Bug fixes and improvementsPowerShell App Deployment Toolkit: PowerShell App Deployment Toolkit v3.1.2: Added Get-IniValue / Set-IniValue functions. Replaces Get-IniContent / Set-IniContent which were a bit unwieldy. The new functions are much easier to use. Added -Value parameter to Get-RegistryKey so that a specific registry value can be retrieved instead of the entire Key as an object Fixed Test-Battery to work with machines that can have multiple batteries Fixed issue where BlockExecution would fail if a Custom Temp Path was specified in the config file Updated examples with latest ...Microsoft Script Analyzer: Microsoft Script Analyzer 1.1: The Script Analyzer scans your current PowerShell script code against some PowerShell best practice rules, and provide suggestions to improve the script quality and readability. By double-clicking the checking result, the relevant script code will be highlighted in the code editor. Script Analyzer result You can configure the Script Analyzer rules in the Settings window of Script Analyzer. Script Analyzer settings The current release includes 5 PowerShell best practice rules. Invoke-...Microsoft Script Browser: Script Browser 1.1: Script Browser for Windows PowerShell ISE was designed and developed in response to many IT Pros’ and MVPs’ feedback during the MVP Global Summit. It puts nearly 10K script examples at IT Pros fingertips when they write scripts to automate their IT tasks. Users can search, learn, download and manage scripts from within their scripting environment - PowerShell ISE - with just a few button clicks. It saves the time of switching back and forth between webpages and scripting environment, and also...New ProjectsAOP.Net: this project is used to implement AOP in .NetARTYKLES: Project articles ASP.NET Identity 2.0 Azure Table Storage: This project provides a high performance cloud solution for ASP.NET Identity 2.0 using Azure Table storage replacing the Entity Framework / MSSQL provider.Associativy Taxonomies Adapter: Administration module for the Associativy (http://associativy.com) Orchard graph platform.BancoSim: BancoSim inicioChaosKit: Chaos theory based time series analysis library, calculating Lyapunov and Hurst exponents and making iterated predictions.ElectrodomesticosAbr2014: Proyecto de ElectrodomesticosGPM: general privilege systemLNTest: LNTestLocal Electrodomésticos 001: Se tiene un local de electrodomésticos que tiene intensión de salir a online. MVC - Filtered TextBox: The project contains MVC Html helper methods for rendering a filtered text box that allows the user to enter only a given set of characters.MvcTrialer: A simple class for .NET 4 MVC to redirect pages if users exceeded a trial period date.NotificationsExtensions.Portable: Portable Class Library Version of the NotificationsExtensions NuGet Packages. Used to Create WinRT/Windows Phone Notification XML.OBD-II: Cross platform library for communicating with OBD-II adapters.Powershell Analyze Robocopy Logs and mail its results: It analyzes a path with Robocopy Log files. It'll create a summary file with information about all log files and it'll mail its results.Proyecto Electrodomesticos: proyecto electrodomesticosPrueba1: asdPVT Library: PVT library for calculating the thermodynamic properties of fluidQuanLyPhongMachThuY: Project serve for .NET CourcseRAMED: project that give some functionalities to ramed projects management like permissions and capabilities to make the management of this type of projects easierSimple Contacts: Simple Contacts Directory application built with ASP.NET MVC and Web API that perform basic CRUD (create, read, update, delete) operations.Stream oriented base64 encoder and decoder: Very simple implementation of stream oriented base64 encoder and decoder, which uses standard .NET Stream decorators. Super Casa de Electronica: no se q escribirTiny Deduplicator: Tiny Deduplicator is a file deduplicator which can scan for duplicate files, and allows the user to control which duplicates they are going to keep or recycle.webdemo: DemonstrationWindows Embedded Compact Edition 2013 File Transfer: A console app for transferring files using TCPIP between Windows Embedded Compact devices, and between them and the desktop. Compact 2013 and Desktop versions.Windows Tile Updater: An simple example of using the Microsoft Universal App to update a tile on the start screen. This was created to accompany a series of blog posts.WMI.NET: WMI.NET Demo Project form Win32 ClassesWumper Thumpers: The ultimate sweg

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• Management Reporter Installation – Lessons Learned

  - by Ryan McBee

  After successfully completing several installations of Management Reporter this year, I wanted to share a few lessons learned that should help you. First, you will want to make sure that you install Management Reporter under a domain account as opposed to a local system or network service account. Management Reporter gives you the option to install under these accounts, but it is a be a best practice approach to use a domain account. Upon installation of Management Report, you will want to make sure that Directory Browsing is enabled within the IIS server of your site or you will have problems when you go to use Management Reporter. By default, it will be disabled in Server 2008 R2 and you will need to make the setting change under the Actions pane shown below. Lastly, you will want to make sure that SQL Server is running under a domain account. I have had multiple situations where reports have been stuck in the Queued status rather than Processing status of Management Reporter. After reviewing resolution 5 of KB 2298248, it was determined that running SQL Server under a domain account is the way to go.

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• Mac-like alt-tab replacement for Windows 7?

  - by calavera

  Is there an alt-tab replacement for windows that works in the same manner as command-tab and command-tick on OS X? example of what I'd like to do: If I hit alt-tab, I'd like to switch between open applications, rather than all windows currently open. If I hit alt-tick, I'd like to switch between open windows of the same application. VistaSwitcher is almost there, in that it allows you to alt-tick switch between windows of the same app. So if I have 4 firefox windows open and one of them is my active window, I can alt-tick to switch between those 4 while ignoring any other open apps. However, VistaSwitcher's alt-tab functionality is similar to stock Windows alt-tab, where you cycle through all open windows, regardless of whether there are multiple instances of certain applications.

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• How can I set up sendmail to forward all mail to an external MTA?

  - by unknown (google)

  We have multiple applications that currently talk SMTP to an external MTA. The emails have arbitrary destination domains (they're emails to be sent to our users), but all from the same internal domain ([email protected]). I want to set up an internal MTA (i guess with sendmail) that queues all mails, and have the internal MTA forward these emails to the external MTA, because the external MTA occasionally goes down and this causes various problems in our applications. I figure I can set up sendmail as a queuing middleware. If the above assumptions are correct, what would the sendmail configuration look like? The 'mailertable' feature looks promising, and so does 'SMART_HOST'. Any thoughts before I explore these possibilities? Jae

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• What is the best book on Silverlight 4?

  - by mbcrump

  Silverlight/Expression 4 Books! I recently stumbled upon a post asking, “What is the best book on Silverlight 4?” In the age of the internet, it can be hard for anyone searching for a good book to actually find it. I have read a few Silverlight 4/Expression books in 2010 and decided to post the “best of” collection. Instead of reading multiple books, you can cut your list down to whatever category that you fit in. With Silverlight 5 coming soon, now is the time to get up to speed with what Silverlight 4 can offer. Be sure to read the full review at the bottom of each section. For the “Beginner” Silverlight Developer: Both of these books contains very simple applications and will get you started very fast. and Book Review: Microsoft Silverlight 4 Step by Step For the guy/gal that wants to “Master” Expression Blend 4: This is a hands-on kind of book. Victor get you started early on with some sample application and quickly deep dives into Storyboard and other Animations. If you want to learn Blend 4 then this is the place to start. Book Review: Foundation Expression Blend 4 by Victor Gaudioso If you are aiming to learn more about the Business side of Silverlight then check out the following two books: and Finally, For the Silverlight 4 guy/gal that wants to “Master” Silverlight 4, it really boils down to the following two books: and   Book Review: Silverlight 4 Unleashed by Laurent Bugnion Book Review: Silverlight 4 in Action by Pete Brown I can’t describe how much that I’ve actually learned from both of these books. I would also recommend you read these books if you are preparing for your Silverlight 4 Certification. For a complete list of all Silverlight 4 books then check out http://www.silverlight.net/learn/books/ and don’t forget to subscribe to my blog.  Subscribe to my feed CodeProject

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• Chat client/server that offers certain options.

  - by MrStatic

  A few friends of mine and including me for the past few years have hosted an irc server on one of our dedicated servers. We use it for just personal reasons. We like the aspect of it that it allows private messages and chat rooms. Plus the ability to send/receive files and is cross platform (Linux/Mac/Windows/Mobile). Our domain is about to expire and we are looking to move onto something new. So we are looking for a chat client / server that offers the following: Chatroom (multiple people chatting together in the same box) File transfers Private messages Cross Platform (especially mobile ie: Blackberry and Android) We don't have to host it but that isn't out of the question Logging on the client side (we say a lot of crap and like to go back and quote said crap) SSL/TLS Some sort of encryption some of the stuff said/sent is of a sensitive nature ie: business nature

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• Space a valid delimiter for email addresses in email header?

  - by semanticalo

  Is it syntactically correct to delimit multiple email recipients in the "To" header of an email with spaces only or do I need to use another delimiter (a semicolon or the like)? Example (MIME data reads as follows): Date: Mon, 04 Oct 2010 06:14:16 +0200 From: [email protected] To: [email protected] [email protected] [email protected] Subject: Test Subject The above will be processed by many email processing applications, but I need to know whether it's correct according to standard (RFC). Unfortunately I didn't find anything useful on the internet so far. Thanks a million for your help!

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• Perl: Negative look behind regex question [migrated]

  - by James

  The Perlre in Perldoc didn't go into much detail on negative look around but I tried testing it, and didn't work as expected. I want to see if I can differentiate a C preprocessor macro definition (e.g. #define MAX(X) ....) from actual usage (y = MAX(x);), but it didn't work as expected. my $macroName = 'MAX'; my $macroCall = "y = MAX(X);"; my $macroDef = "# define MAX(X)"; my $boundary = qr{\b$macroName\b}; my $bstr = " MAX(X)"; if($bstr =~ /$boundary/) { print "boundary: $bstr matches: $boundary\n"; } else { print "Error: no match: boundary: $bstr, $boundary\n"; } my $negLookBehind = qr{(?<!define)\b$macroName\b}; if($macroCall =~ /$negLookBehind/) # "y = MAX(X)" matches "(?<!define)\bMAX\b" { print "negative look behind: $macroCall matches: $negLookBehind\n"; } else { print "no match: negative look behind: $macroCall, $negLookBehind\n"; } if($macroDef =~ /$negLookBehind/) # "#define MAX(X)" should not match "(?<!define)\bMAX\b" { print "Error: negative look behind: $macroDef matches: $negLookBehind\n"; } else { print "no match: negative look behind: $macroDef, $negLookBehind\n"; } It seems that both $macroDef and $macroCall seem to match regex /(?<!define)\b$macroName\b/. I backed off from the original /(?<\#)\s*(?<!define)\b$macroName\b/ since that didn't work either. So what did I screw up? Also does Perl allow chaining of multiple look around expressions?

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• D key not working on Ubuntu

  - by Jonathan

  For some inexplicable reason the capital d key on my Ubuntu system is no longer producing output. Hitting caps lock and then d produces a D. I've tried multiple keyboards and the issue is the same. There's nothing bound to Shift+d under System Preferences Keyboard Shortcuts. xev produces the following: shift + a KeyPress event, serial 36, synthetic NO, window 0x4c00001, root 0x27a, subw 0x0, time 31268952, (130,-16), root:(1000,525), state 0x10, keycode 62 (keysym 0xffe2, Shift_R), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyPress event, serial 36, synthetic NO, window 0x4c00001, root 0x27a, subw 0x0, time 31269376, (130,-16), root:(1000,525), state 0x11, keycode 38 (keysym 0x41, A), same_screen YES, XLookupString gives 1 bytes: (41) "A" XmbLookupString gives 1 bytes: (41) "A" XFilterEvent returns: False KeyRelease event, serial 36, synthetic NO, window 0x4c00001, root 0x27a, subw 0x0, time 31269584, (130,-16), root:(1000,525), state 0x11, keycode 38 (keysym 0x41, A), same_screen YES, XLookupString gives 1 bytes: (41) "A" XFilterEvent returns: False KeyRelease event, serial 36, synthetic NO, window 0x4c00001, root 0x27a, subw 0x0, time 31269608, (130,-16), root:(1000,525), state 0x11, keycode 62 (keysym 0xffe2, Shift_R), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False shift + d KeyPress event, serial 36, synthetic NO, window 0x4c00001, root 0x27a, subw 0x0, time 31102792, (115,-13), root:(985,528), state 0x10, keycode 62 (keysym 0xffe2, Shift_R), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False FocusOut event, serial 36, synthetic NO, window 0x4c00001, mode NotifyGrab, detail NotifyAncestor FocusIn event, serial 36, synthetic NO, window 0x4c00001, mode NotifyUngrab, detail NotifyAncestor KeymapNotify event, serial 36, synthetic NO, window 0x0, keys: 2 0 0 0 0 0 0 64 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 KeyRelease event, serial 36, synthetic NO, window 0x4c00001, root 0x27a, subw 0x0, time 31103104, (115,-13), root:(985,528), state 0x11, keycode 62 (keysym 0xffe2, Shift_R), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False

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• Windows 7 - Move location of Eventlog

  - by Jörg B.

  I am having a particular nasty problem of my main system drive 'disappearing' all of the sudden while the system is running. The vendor somewhat knows about this but has not managed to fix it completely over multiple fw iterations. Problems I have with the support is that I cannot provide any particular system log files/entries to further analyse what might have been going on because, well - windows cannot write to its 'lost' drive before bsod'ing. Is there any way to configure where Windows 7 stores its event logs so that I could specify a second physical hdd?

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• C#: Handling Notifications: inheritance, events, or delegates?

  - by James Michael Hare

  Often times as developers we have to design a class where we get notification when certain things happen. In older object-oriented code this would often be implemented by overriding methods -- with events, delegates, and interfaces, however, we have far more elegant options. So, when should you use each of these methods and what are their strengths and weaknesses? Now, for the purposes of this article when I say notification, I'm just talking about ways for a class to let a user know that something has occurred. This can be through any programmatic means such as inheritance, events, delegates, etc. So let's build some context. I'm sitting here thinking about a provider neutral messaging layer for the place I work, and I got to the point where I needed to design the message subscriber which will receive messages from the message bus. Basically, what we want is to be able to create a message listener and have it be called whenever a new message arrives. Now, back before the flood we would have done this via inheritance and an abstract class: 1:  2: // using inheritance - omitting argument null checks and halt logic 3: public abstract class MessageListener 4: { 5: private ISubscriber _subscriber; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber) 11: { 12: _subscriber = subscriber; 13: _messageThread = new Thread(MessageLoop); 14: _messageThread.Start(); 15: } 16:  17: // user will override this to process their messages 18: protected abstract void OnMessageReceived(Message msg); 19:  20: // handle the looping in the thread 21: private void MessageLoop() 22: { 23: while(!_isHalted) 24: { 25: // as long as processing, wait 1 second for message 26: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 27: if(msg != null) 28: { 29: OnMessageReceived(msg); 30: } 31: } 32: } 33: ... 34: } It seems so odd to write this kind of code now. Does it feel odd to you? Maybe it's just because I've gotten so used to delegation that I really don't like the feel of this. To me it is akin to saying that if I want to drive my car I need to derive a new instance of it just to put myself in the driver's seat. And yet, unquestionably, five years ago I would have probably written the code as you see above. To me, inheritance is a flawed approach for notifications due to several reasons: Inheritance is one of the HIGHEST forms of coupling. You can't seal the listener class because it depends on sub-classing to work. Because C# does not allow multiple-inheritance, I've spent my one inheritance implementing this class. Every time you need to listen to a bus, you have to derive a class which leads to lots of trivial sub-classes. The act of consuming a message should be a separate responsibility than the act of listening for a message (SRP). Inheritance is such a strong statement (this IS-A that) that it should only be used in building type hierarchies and not for overriding use-specific behaviors and notifications. Chances are, if a class needs to be inherited to be used, it most likely is not designed as well as it could be in today's modern programming languages. So lets look at the other tools available to us for getting notified instead. Here's a few other choices to consider. Have the listener expose a MessageReceived event. Have the listener accept a new IMessageHandler interface instance. Have the listener accept an Action<Message> delegate. Really, all of these are different forms of delegation. Now, .NET events are a bit heavier than the other types of delegates in terms of run-time execution, but they are a great way to allow others using your class to subscribe to your events: 1: // using event - ommiting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private bool _isHalted = false; 6: private Thread _messageThread; 7:  8: // assign the subscriber and start the messaging loop 9: public MessageListener(ISubscriber subscriber) 10: { 11: _subscriber = subscriber; 12: _messageThread = new Thread(MessageLoop); 13: _messageThread.Start(); 14: } 15:  16: // user will override this to process their messages 17: public event Action<Message> MessageReceived; 18:  19: // handle the looping in the thread 20: private void MessageLoop() 21: { 22: while(!_isHalted) 23: { 24: // as long as processing, wait 1 second for message 25: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 26: if(msg != null && MessageReceived != null) 27: { 28: MessageReceived(msg); 29: } 30: } 31: } 32: } Note, now we can seal the class to avoid changes and the user just needs to provide a message handling method: 1: theListener.MessageReceived += CustomReceiveMethod; However, personally I don't think events hold up as well in this case because events are largely optional. To me, what is the point of a listener if you create one with no event listeners? So in my mind, use events when handling the notification is optional. So how about the delegation via interface? I personally like this method quite a bit. Basically what it does is similar to inheritance method mentioned first, but better because it makes it easy to split the part of the class that doesn't change (the base listener behavior) from the part that does change (the user-specified action after receiving a message). So assuming we had an interface like: 1: public interface IMessageHandler 2: { 3: void OnMessageReceived(Message receivedMessage); 4: } Our listener would look like this: 1: // using delegation via interface - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private IMessageHandler _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler.OnMessageReceived(msg); 28: } 29: } 30: } 31: } And they would call it by creating a class that implements IMessageHandler and pass that instance into the constructor of the listener. I like that this alleviates the issues of inheritance and essentially forces you to provide a handler (as opposed to events) on construction. Well, this is good, but personally I think we could go one step further. While I like this better than events or inheritance, it still forces you to implement a specific method name. What if that name collides? Furthermore if you have lots of these you end up either with large classes inheriting multiple interfaces to implement one method, or lots of small classes. Also, if you had one class that wanted to manage messages from two different subscribers differently, it wouldn't be able to because the interface can't be overloaded. This brings me to using delegates directly. In general, every time I think about creating an interface for something, and if that interface contains only one method, I start thinking a delegate is a better approach. Now, that said delegates don't accomplish everything an interface can. Obviously having the interface allows you to refer to the classes that implement the interface which can be very handy. In this case, though, really all you want is a method to handle the messages. So let's look at a method delegate: 1: // using delegation via delegate - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler(msg); 28: } 29: } 30: } 31: } Here the MessageListener now takes an Action<Message>.  For those of you unfamiliar with the pre-defined delegate types in .NET, that is a method with the signature: void SomeMethodName(Message). The great thing about delegates is it gives you a lot of power. You could create an anonymous delegate, a lambda, or specify any other method as long as it satisfies the Action<Message> signature. This way, you don't need to define an arbitrary helper class or name the method a specific thing. Incidentally, we could combine both the interface and delegate approach to allow maximum flexibility. Doing this, the user could either pass in a delegate, or specify a delegate interface: 1: // using delegation - give users choice of interface or delegate 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // passes the interface method as a delegate using method group 19: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 20: : this(subscriber, handler.OnMessageReceived) 21: { 22: } 23:  24: // handle the looping in the thread 25: private void MessageLoop() 26: { 27: while(!_isHalted) 28: { 29: // as long as processing, wait 1 second for message 30: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 31: if(msg != null) 32: { 33: _handler(msg); 34: } 35: } 36: } 37: } } This is the method I tend to prefer because it allows the user of the class to choose which method works best for them. You may be curious about the actual performance of these different methods. 1: Enter iterations: 2: 1000000 3:  4: Inheritance took 4 ms. 5: Events took 7 ms. 6: Interface delegation took 4 ms. 7: Lambda delegate took 5 ms. Before you get too caught up in the numbers, however, keep in mind that this is performance over over 1,000,000 iterations. Since they are all < 10 ms which boils down to fractions of a micro-second per iteration so really any of them are a fine choice performance wise. As such, I think the choice of what to do really boils down to what you're trying to do. Here's my guidelines: Inheritance should be used only when defining a collection of related types with implementation specific behaviors, it should not be used as a hook for users to add their own functionality. Events should be used when subscription is optional or multi-cast is desired. Interface delegation should be used when you wish to refer to implementing classes by the interface type or if the type requires several methods to be implemented. Delegate method delegation should be used when you only need to provide one method and do not need to refer to implementers by the interface name.

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• How can i control how much Authority RRs a DNS answer returns ?

  - by Benoît

  Hello, i quite don't understand Authority RRs. Using dig to resolve some random A records, my caching DNS server sometimes also return Authority RRs and sometimes not. The number and the type of the returned Authority RRs also vary a lot. What does control whether Authority RRs are returned or not on a standard client query ? Is it a client or server setting ? What does control how many Authoriy RRs are returned ? What does control of the type of the Authority RRs records returned ? Sometimes it's multiple NS, sometimes it's a SOA. It's also often comes with Additional RRs of type A about the Authority RRs NS returned. I'm really looking for a RFC or kind of describing this. Thanks.

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• Recommended website performance monitoring services? [closed]

  - by Dennis G.

  I'm looking for a good performance monitoring service for websites. I know about some of the available general monitoring services that check for uptime and notify you about unavailable services. But I'm specifically looking for a service with an emphasis on performance. I.e., I would like to see reports with detailed performance statistics from multiple locations world-wide, with a break-down on how long it took to fetch the different website resources, including third-party scripts such as Google Analytics and so on (the report should contain similar details such as the FireBug Net tab). Are there any such services and if so, which one is the best?

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• apache generating to many rotatelogs.exe on Windows?

  - by Patrick

  I'm seeing some odd behavior with Apache's rotatelogs.exe. On one of my servers I'm seeing multiple rotatelogs.exe counting into the 100's. Normally I usually only see 6 which I can rationalize to the 3 logs I have rotating. Does anyone know why this might be happening and how I can prevent it from happening. When the rotatelogs.exe processes get up into the 100's everything slows down and Apache is effectively shutdown because it can't process requests anymore. We are using the following line in our httpd.conf file: ErrorLog "|\"C:/Program Files/Apache2/bin/rotatelogs.exe\" \"C:/Program Files/Apache2/logs/error_log.%Y-%m-%d-%H_%M_%S\" 20M" Thanks in advance for the help!

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• Video for an ads-driven web-site

  - by AntonAL

  I have a website, wich i will fill with a bunch of useful videos. I've implemented an ads rotation engine for articles and will do so for videos. The next milestone is to decide, how video will be integrated. They are two ways: To host videos myself. Pros: complete freedom. Cons: need tens of gigabytes of storage; support for multiple formats to be crossbrowser and crossdevice. Use Youtube. Pros: Very simple to use; nothing to do. What are pros and cons for each way ? Some questions for YouTube: Will i be able to control playback of YouTube-embedded video to make post-rolls ? What is ranking impact on my web-site, when most of pages will refer to YouTube ? Will, say, iPad play video, embedded via YouTube's iframe ? Does relying entirely on YouTube have a long-term perspective for a web-site, that should bring money ?

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• Black stripe appears to the right of the screen, impossible to get rid of

  - by Gabriele Cirulli

  After clicking the "Auto Config" button on my Acer AL2216w screen a stripe appeared on the right of the screen where the screen doesn't "exist" and I can't seem to take the screen viewport back even by using the OCD setting and moving it to the right. The left part of the screen is also hidden and I'm not able to see what's going on there. The PC is connected to the screen through a DVI adapter and a VGA cable. I also use multiple monitors and this is the second monitor. Anyway this seems not to be a related issue, as this used to happen even when I only had a single monitor. I managed to fix this issue once but it was more than two years ago and I can't remember what I did, and out of all of the things I've tried so far (connecting the screen to another PC and performing auto adjustment, switching the cables, etc.) none worked. Here's how it looks: Can anyone help me fix this?

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• Does Dynamic DNS require separate subdomains?

  - by kce

  Hello. I have a functioning DHCP/DNS (ISC Bind 9.6, DHCP 3.1.1) server running on Debian that I would like to add DynamicDNS functionality to. I have a pretty simple question: Does DynamicDNS require (or recommend) separate sub-domains? I have seen a few tutorials where the the clients that are acquiring their IP addresses and other networking information via DHCP are on a different sub-domain as the servers which are statically configured (both in terms of IP, and DNS). For example: All the clients are on ws.example.org and the servers on example.org. Right now all of our servers and clients are in the same domain (example.org) but spread across different zone files (because we have multiple subnets). The clients are configured with DHCP and the servers are configured statically. If I want to setup DynamicDNS for the clients should I use a separate sub-domain? What's the best practice here (and why or why not would it be a bad idea to do otherwise)? Thanks.

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• SQL SERVER – Using MAXDOP 1 for Single Processor Query – SQL in Sixty Seconds #008 – Video

  - by pinaldave

  Today’s SQL in Sixty Seconds video is inspired from my presentation at TechEd India 2012 on Speed up! – Parallel Processes and Unparalleled Performance. There are always special cases when it is about SQL Server. There are always few queries which gives optimal performance when they are executed on single processor and there are always queries which gives optimal performance when they are executed on multiple processors. I will be presenting the how to identify such queries as well what are the best practices related to the same. In this quick video I am going to demonstrate if the query is giving optimal performance when running on single CPU how one can restrict queries to single CPU by using hint OPTION (MAXDOP 1). More on Errors: Difference Temp Table and Table Variable – Effect of Transaction Effect of TRANSACTION on Local Variable – After ROLLBACK and After COMMIT Debate – Table Variables vs Temporary Tables – Quiz – Puzzle – 13 of 31 I encourage you to submit your ideas for SQL in Sixty Seconds. We will try to accommodate as many as we can. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Video

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• Are there any actual case studies on rewrites of software success/failure rates?

  - by James Drinkard

  I've seen multiple posts about rewrites of applications being bad, peoples experiences about it here on Programmers, and an article I've ready by Joel Splosky on the subject, but no hard evidence of case studies. Other than the two examples Joel gave and some other posts here, what do you do with a bad codebase and how do you decide what to do with it based on real studies? For the case in point, there are two clients I know of that both have old legacy code. They keep limping along with it because as one of them found out, a rewrite was a disaster, it was expensive and didn't really work to improve the code much. That customer has some very complicated business logic as the rewriters quickly found out. In both cases, these are mission critical applications that brings in a lot of revenue for the company. The one that attempted the rewrite felt that they would hit a brick wall at some point if the legacy software didn't get upgraded at some point in the future. To me, that kind of risk warrants research and analysis to ensure a successful path. My question is have there been actual case studies that have investigated this? I wouldn't want to attempt a major rewrite without knowing some best practices, pitfalls, and successes based on actual studies. Aftermath: okay, I was wrong, I did find one article: Rewrite or Reuse. They did a study on a Cobol app that was converted to Java.

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• Constructs for wrapping a hardware state machine

  - by Henry Gomersall

  I am using a piece of hardware with a well defined C API. The hardware is stateful, with the relevant API calls needing to be in the correct order for the hardware to work properly. The API calls themselves will always return, passing back a flag that advises whether the call was successful, or if not, why not. The hardware will not be left in some ill defined state. In effect, the API calls advise indirectly of the current state of the hardware if the state is not correct to perform a given operation. It seems to be a pretty common hardware API style. My question is this: Is there a well established design pattern for wrapping such a hardware state machine in a high level language, such that consistency is maintained? My development is in Python. I ideally wish the hardware state machine to be abstracted to a much simpler state machine and wrapped in an object that represents the hardware. I'm not sure what should happen if an attempt is made to create multiple objects representing the same piece of hardware. I apologies for the slight vagueness, I'm not very knowledgeable in this area and so am fishing for assistance of the description as well!

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• Failed to spawn test

  - by Lost

  Running a simple test in Ubuntu 12.04: sudo lxc-execute -n test /bin/bash -l debug -o outout Got error message: lxc-execute: failed to spawn 'test' cat outout: lxc-execute 1347053658.113 DEBUG lxc_start - sigchild handler set lxc-execute 1347053658.113 INFO lxc_start - 'test' is initialized lxc-execute 1347053658.366 DEBUG lxc_start - Dropping cap_sys_boot and watching utmp lxc-execute 1347053658.366 DEBUG lxc_cgroup - checking '/' (rootfs) lxc-execute 1347053658.366 DEBUG lxc_cgroup - checking '/sys' (sysfs) lxc-execute 1347053658.366 DEBUG lxc_cgroup - checking '/proc' (proc) lxc-execute 1347053658.366 DEBUG lxc_cgroup - checking '/dev' (devtmpfs) lxc-execute 1347053658.366 DEBUG lxc_cgroup - checking '/dev/pts' (devpts) lxc-execute 1347053658.367 DEBUG lxc_cgroup - checking '/run' (tmpfs) lxc-execute 1347053658.367 DEBUG lxc_cgroup - checking '/' (ext3) lxc-execute 1347053658.367 DEBUG lxc_cgroup - checking '/sys/fs/fuse/connections' (fusectl) lxc-execute 1347053658.367 DEBUG lxc_cgroup - checking '/sys/kernel/debug' (debugfs) lxc-execute 1347053658.367 DEBUG lxc_cgroup - checking '/sys/kernel/security' (securityfs) lxc-execute 1347053658.367 DEBUG lxc_cgroup - checking '/run/lock' (tmpfs) lxc-execute 1347053658.367 DEBUG lxc_cgroup - checking '/run/shm' (tmpfs) lxc-execute 1347053658.367 DEBUG lxc_cgroup - checking '/run/rpc_pipefs' (rpc_pipefs) lxc-execute 1347053658.367 DEBUG lxc_cgroup - checking '/scratch/WAMC-Simulation' (nfs) lxc-execute 1347053658.367 DEBUG lxc_cgroup - checking '/share' (nfs) lxc-execute 1347053658.367 DEBUG lxc_cgroup - checking '/proj/WAMC-Simulation' (nfs) lxc-execute 1347053658.367 DEBUG lxc_cgroup - checking '/users/bhu' (nfs) lxc-execute 1347053658.367 ERROR lxc_start - failed to spawn 'test' Run command: sudo lxc-checkconfig Kernel config /proc/config.gz not found, looking in other places... Found kernel config file /boot/config-2.6.38.7-1.0emulab --- Namespaces --- Namespaces: enabled Utsname namespace: enabled Ipc namespace: enabled Pid namespace: enabled User namespace: enabled Network namespace: enabled Multiple /dev/pts instances: enabled --- Control groups --- Cgroup: enabled Cgroup namespace: enabled Cgroup device: enabled Cgroup sched: enabled Cgroup cpu account: enabled Cgroup memory controller: enabled Cgroup cpuset: enabled --- Misc --- Veth pair device: enabled Macvlan: enabled Vlan: enabled File capabilities: enabled Note : Before booting a new kernel, you can check its configuration usage : CONFIG=/path/to/config /usr/bin/lxc-checkconfig What's the problem? Thanks a lot

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