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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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• 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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• 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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• 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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• 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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• Which would be a better way to load data via ajax

  - by Mike

  I am using google maps and returning html/lat/long from my MySQL database Currently A user picks a business category e.g; "Video Production". an ajax call is sent to a CodeIgniter controller the Controller then queries the db, and returns the following data via JSON Lat/Long of the marker HTML for the popup window this is approximately 34 rows in the database across two tables per business the ajax call receives this data and then plots the marker along with the html onto the map The data that is returned from the controller is one big json object... This is done for all businesses that exist in the Video Production category (currently approx 40 businesses). As you can see, pulling this data for multiple categories (100s of businesses) can get very very taxing on the server. My question is Would it be more beneficial to modify the process flow as such: a user picks a business category e.g; "Video Production". an ajax call is sent to a CodeIgniter controller the controller then queries the database for the location base information lat/long level (used to change marker icon color) This would be a single row per business with several columns the ajax call receives this data and then plots the marker on the map when the user clicks a marker an ajax call is sent to a CodeIgniter Controller the controller queries the database for the HTML and additional data based on business_id and if not, what are some better suggestions to this problem? In summary this means rather than including the HTML and additional data along for each business, only submitting minimal location information and then re-query for that information when each business marker is clicked. Potential Downsides longer load times when a user clicks a marker icon more code?? more queries to the database

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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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• 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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• 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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• 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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• 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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• 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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• 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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• Math questions at a programmer interview?

  - by anon

  So I went to an interview at Samsung here in Dallas, Texas. The way the recruiter described the job, he didn't make it sound like it was too math-oriented. The job basically involved graphics programming and C++. Yes, math is implied in graphics programming, especially shaders, but I still wasn't expecting this... The whole interview lasted about an hour and a half and they asked me nothing but math-related questions. They didn't ask me a single programming question, which I found odd. About all they did was ask me how to write certain math routines as a C++ function, but that's about it. What about programming philosophy questions? Design patterns? Code-correctness? Constness? Exception safety? Thread safety? There are a zillion topics that they could have covered. But they didn't. The main concern I have is that they didn't ask any programming questions. This basically implies to me that any programmer who is good at math can get a job here, but they might put out terrible code. Of course, I think I bombed the interview because I haven't used any sort of linear algebra in about a year and I forget math easily if I haven't used it in practice for a while. Are any of my other fellow programmers out there this way? I'm a game programmer too, so this seems especially odd. The more I learn, the more old knowledge that gets "popped" out of my "stack" (memory). My question is: Does this interview seem suspicious? Is this a typical interview that large corporations have? During the interview they told me that Google's interview process is similar. They have multiple, consecutive interviews where the math problems get more advanced.

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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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• 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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• 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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• WCF/webservice architecture question

  - by M.R.

  I have a requirement to create a webservice to expose certain items from a CMS as a web service, and I need some suggestions - the structure of the items is as such: item - field 1 - field 2 - field 3 - field 4 So, one would think that the class for this will be: public class MyItem { public string ItemName { get; set; } public List<MyField> Fields { get; set; } } public class MyField { public string FieldName { get; set; } public string FieldValue { get; set; } //they are always string (except - see below) } This works for when its always one level deep, but sometimes, one of the fields is actually a point to ANOTHER item (MyItem) or multiple MyItem (List<MyItem>), so I thought I would change the structure of MyField as follows, to make FieldValue as object; public class MyField { public string FieldName { get; set; } public object FieldValue { get; set; } //changed to object } So, now, I can put whatever I want in there. This is great in theory, but how will clients consume this? I suspect that when users make a reference to this web service, they won't know which object is being returned in that field? This seems like a not-so-good design. Is there a better approach to this?

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• Forwarding emails from a domain

  - by Euwyn

  I generally use Google Apps to handle email domains. I'm unfortunately stuck in an infinite loop with Google [1] for one the domains I recently picked up. Right now I use Zerigo's awesome DNS services. How can I get [email protected] forwarded to my Gmail account? Better yet if this is a free/cheap solution and can work with multiple aliases going to different real email addresses ([email protected] - [email protected], [email protected] - [email protected]) [1] Long story. I alternate between "Sorry, you've reached a login page for a domain that isn't using Google Apps." and "This domain has already been registered with Google Apps." Seems like many others are having this issue and Google isn't doing anything about it.

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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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• 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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• 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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• One bigger Virtual Machine distributed across many OpenStack nodes [duplicate]

  - by flyer

  This question already has an answer here: Can a virtualized machine have the CPU and RAM resources of multiple underlying physical machines? 2 answers I just setup virtual machines on one hardware with Vagrant. I want to use a Puppet to configure them and next try to setup OpenStack. I am not sure If I am understanding how this should look at the end. Is it possible to have below architecture with OpenStack after all where I will run one Virtual Machine with Linux? ------------------------------- | VM with OS | ------------------------------- | NOVA | NOVA | NOVA | ------------------------------- | OpenStack | ------------------------------- | Node | Node | Node | ------------------------------- More details: In my environment Nodes are just virtual machines, but my question concerns separate Hardware nodes. If we imagine this Nodes(Novas) are placed on a separate machines (e.g. every has 4 cores) can I run one Virtual Machine across many OpenStack Nodes? Is it possible to aggregate the computation power of OpenStack in one virtual distributed operating system?

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