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• NSMutableURLRequest wont turn on 3G

  - by Kyle

  I won't bother posting any code because my code works fine when I launch Safari or something that turns on the 3G connection first. When I put it Airport mode, then put back OFF, I will get the behavior of a connection error saying No internet connection with NSMutableURLRequest. I've personally mailed apple about how the Ant gets turned on and off, and they said anything that uses their base CFSocketStream object will turn on the Ant, and I quote: "such as NSURLRequest".. BSD Sockets do not, just so everyone knows.. However, I assumed NSMutableURLRequest would fall into the category of 'Does', but it seems like it doesnt. It never succeeds for me when I cycle Airport or have the phone idle for a long time. It will ALWAYS succeed when I open any other network app first to turn the Ant on. Shall I be forced to do a dummy NSURLRequest call to turn this on; or has anyone been able to get this class working just fine? Remember this is just an implementation of NSMutableURLRequest to upload a file Async, and no other Network operations are performed anywhere; no ads, no version checks, no nothing.

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• Is an "infinite" iterator bad design?

  - by Adamski

  Is it generally considered bad practice to provide Iterator implementations that are "infinite"; i.e. where calls to hasNext() always(*) return true? Typically I'd say "yes" because the calling code could behave erratically, but in the below implementation hasNext() will return true unless the caller removes all elements from the List that the iterator was initialised with; i.e. there is a termination condition. Do you think this is a legitimate use of Iterator? It doesn't seem to violate the contract although I suppose one could argue it's unintuitive. public class CyclicIterator<T> implements Iterator<T> { private final List<T> l; private Iterator it; public CyclicIterator<T>(List<T> l) { this.l = l; this.it = l.iterator(); } public boolean hasNext() { return !l.isEmpty(); } public T next() { T ret; if (!hasNext()) { throw new NoSuchElementException(); } else if (it.hasNext()) { ret = it.next(); } else { it = l.iterator(); ret = it.next(); } return ret; } public void remove() { it.remove(); } }

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• Suggestions for a PHP programmer wanting to create a timer app for an internet cafe

  - by grokker

  Hi, I was asked by a friend to make a timer app for his small internet cafe. He wants to have timers on each client PCs. The timers indicate how much time has been spent by the customer. On the PC that he uses, there's another program that has the overview of all the timers and there's a button for each client PCs that allows him to blacken out the screen. It's not automatic hence the button. The problem is I haven't done any desktop apps before so that's why I'm asking you guys (the awesome people at SO) for suggestions/advice on what language/tool to use. A little info about me: I did Java but haven't tried Swing though. I know a bit about Python and Ruby too. I don't mind learning new languages as long as I get to finish or get a prototype up and running. He doesn't mind if I could show him a prototype, it's actually for me. It gives me satisfaction to see I'm progressing. I'm not planning on asking him to pay me for doing this. Whatever he gives me is fine. P.S. He's using Windows XP

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• Basic Subversion questions

  - by Epitaph

  I've just started using subversion, and have read the official documentation (svn book), cheat sheet and a couple of guides. I know how to install subversion (in linux), create a repository (svnadmin create), and import my Eclipse project into the repository (SVN import), view the repository files (using svn list). But I am unable to understand some of the other terminologies. For example, after importing my Eclipse project into the newly created repository I have made changes to my Eclipse project (more than 1 file). Now, how should I update the repository with this added files/changes made to my Eclipse project? The svn update command brings the changes from the repository into your working copy - which is the opposite of what I want i.e. bring the changes I made in my Eclipse project into the previously imported project in repository. If I am correct, you update the repository more often (as you keep extending your project implementation) than your current project (with update). Also, I do not understand when would you use svn merge. The svn book states it applies the differences between 2 sources to a working copy. Is there a scenario which would explain this? Finally, can I have more than 1 project checked into the repository? Or is it better to create a new repository for each project?

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• Colorbox with bxslider not working

  - by Bill K

  Hello I am trying to use bxslider with colorbox. My implementation of bxslider is like an example listed here. The difference is that I want only the pagers to be shown. Also when the user clicks one pager I want colorbox to open and have next and previous buttons. The problem is that I cant group the images with colorbox and next and previous button is not shown! The following code uses the rel option but with this way colorbox doesnt event start. What I have tried till now is: HTML <div class="slider_mini" style="position:relative;bottom:0px;"> <div id="bx-pager"> <a data-slide-index="0" href="image.jpg" class="imgz"><img style="width:130px;height:104px;" src="image.jpg"/></a> <a data-slide-index="1" href="image2.jpg" class="imgz"><img style="width:130px;height:104px;" src="image2.jpg"/></a> <a data-slide-index="2" href="image3.jpg" class="imgz"><img style="width:130px;height:104px;" src="image3.jpg"/></a> </div> </div> SCRIPT <script type="text/javascript"> $(document).ready(function(){ $('.imgz').colorbox({rel:'imgz'}); $('.bxslider.two').bxSlider({ pagerCustom: '#bx-pager' }); $('#bx-pager').bxSlider({ slideWidth: 130, minSlides: 2, maxSlides: 3, moveSlides: 1, slideMargin: 10 }); }); </script> Not working Fiddle. Feedback: The problem was in live website that I was calling colorbox before bxslider. I put the call after bxslider's and it works. Thank you.

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• Industry-style practices for increasing productivity in a small scientific environment

  - by drachenfels

  Hi, I work in a small, independent scientific lab in a university in the United States, and it has come to my notice that, compared with a lot of practices that are ostensibly followed in the industry, like daily checkout into a version control system, use of a single IDE/editor for all languages (like emacs), etc, we follow rather shoddy programming practices. So, I was thinking of getting together all my programs, scripts, etc, and building a streamlined environment to increase productivity. I'd like suggestions from people on Stack Overflow for the same. Here is my primary plan.: I use MATLAB, C and Python scripts, and I'd like to edit, compile them from a single editor, and ensure correct version control. (questions/things for which I'd like suggestions are in italics) 1] Install Cygwin, and get it to work well with Windows so I can use git or a similar version control system (is there a DVCS which can work directly from the windows CLI, so I can skip the Cygwin step?). 2] Set up emacs to work with C, Python, and MATLAB files, so I can edit and compile all three at once from a single editor (say, emacs) (I'm not very familiar with the emacs menu, but is there a way to set the path to the compiler for certain languages? I know I can Google this, but emacs documentation has proved very hard for me to read so far, so I'd appreciate it if someone told me in simple language) 3] Start checking in code at the end of each day or half-day so as to maintain a proper path of progress of my code (two questions), can you checkout files directly from emacs? is there a way to checkout LabVIEW files into a DVCS like git? Lastly, I'd like to apologize for the rather vague nature of the question, and hope I shall learn to ask better questions over time. I'd appreciate it if people gave their suggestions, though, and point to any resources which may help me learn.

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• How can I create a dynamic LINQ query in C# with possible multiple group by clauses?

  - by FordPrefect141

  I have been a programmer for some years now but I am a newcomer to LINQ and C# so forgive me if my question sounds particularly stupid. I hope someone may be able to point me in the right direction. My task is to come up with the ability to form a dynamic multiple group by linq query within a c# script using a generic list as a source. For example, say I have a list containing multiple items with the following structure: FieldChar1 - character FieldChar2 - character FieldChar3 - character FieldNum1 - numeric FieldNum2 - numeric In a nutshell I want to be able to create a LINQ query that will sum FieldNum1 and FieldNum2 grouped by any one, two or all three of the FieldChar fields that will be decided at runtime depending on the users requirements as well as selecting the FieldChar fields in the same query. I have the dynamic.cs in my project which icludes a GroupByMany extension method but I have to admit I am really not sure how to put these to use. I am able to get the desired results if I use a query with hard-wired group by requests but not dynamically. Apologies for any erroneous nomenclature, I am new to this language but any advice would be most welcome. Many thanks Alex

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• How does one convert from a Java resultset to ColdFusion query in Railo?

  - by Shawn Grigson

  The following works fine in CFMX 7 and CF8, and I'd assume CF9 as well: <!--- 'conn' is a JDBC connection ---> <cfset stat = conn.createStatement() /> <cfset rs = stat.executeQuery(trim(arguments.sql)) /> <!--- convert this Java resultset to a CF query recordset ---> <cfset queryTable = CreateObject("java", "coldfusion.sql.QueryTable")> <cfset queryTable.init(rs) > <cfset query = queryTable.FirstTable() /> This creates a statement using a JDBC driver, executes a query against it, putting it into a java resultset, and then coldfusion.sql.QueryTable is instantiated, passed the Java resulset object, and then queryTable.FirstTable() is called, which returns an actual coldfusion resultset (for cfloop and the like). The problem comes with a difference in Railo's implementation. Running this code in Railo returns the following error: No matching Constructor for coldfusion.sql.QueryTable(org.sqlite.RS) found. I've dumped the Railo java object, and don't see init() among the methods. Am I missing something simple? I'd love to get this working in Railo as well. Please note: I am doing a DSN-less connection to a SQLite db. I understand how to set up a CF datasource. My only hiccup at this point is doing the translation from a Java result set to a Railo query.

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• Why is python decode replacing more than the invalid bytes from an encoded string?

  - by dangra

  Trying to decode an invalid encoded utf-8 html page gives different results in python, firefox and chrome. The invalid encoded fragment from test page looks like 'PREFIX\xe3\xabSUFFIX' >>> fragment = 'PREFIX\xe3\xabSUFFIX' >>> fragment.decode('utf-8', 'strict') ... UnicodeDecodeError: 'utf8' codec can't decode bytes in position 6-8: invalid data What follows is the summary of replacement policies used to handle decoding errors by python, firefox and chrome. Note how the three differs, and specially how python builtin removes the valid S (plus the invalid sequence of bytes). by Python The builtin replace error handler replaces the invalid \xe3\xab plus the S from SUFFIX by U+FFFD >>> fragment.decode('utf-8', 'replace') u'PREFIX\ufffdUFFIX' >>> print _ PREFIX?UFFIX The python implementation builtin replace error handler looks like: >>> python_replace = lambda exc: (u'\ufffd', exc.end) As expected, trying this gives same result than builtin: >>> codecs.register_error('python_replace', python_replace) >>> fragment.decode('utf-8', 'python_replace') u'PREFIX\ufffdUFFIX' >>> print _ PREFIX?UFFIX by Firefox Firefox replaces each invalid byte by U+FFFD >>> firefox_replace = lambda exc: (u'\ufffd', exc.start+1) >>> codecs.register_error('firefox_replace', firefox_replace) >>> test_string.decode('utf-8', 'firefox_replace') u'PREFIX\ufffd\ufffdSUFFIX' >>> print _ PREFIX??SUFFIX by Chrome Chrome replaces each invalid sequence of bytes by U+FFFD >>> chrome_replace = lambda exc: (u'\ufffd', exc.end-1) >>> codecs.register_error('chrome_replace', chrome_replace) >>> fragment.decode('utf-8', 'chrome_replace') u'PREFIX\ufffdSUFFIX' >>> print _ PREFIX?SUFFIX The main question is why builtin replace error handler for str.decode is removing the S from SUFFIX. Also, is there any unicode's official recommended way for handling decoding replacements?

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• Is there any way to combine transparency and "ajax usability" with HTML templates

  - by Sam

  I'm using HTML_Template_Flexy in PHP but the question should apply to any language or template library. I am outputting a list of relatively complex objects. In the beginning I just iterated over a list of the objects and called a toHtml method on them. When I was about to have my layout designer look over the template I noticed that it was too opaque and that he would have ended up looking through and/or editing many additional php source files to see what really gets generated by the toHtml method. So I extracted most of the HTML strings in the php classes up to the template which made for one clear file where you can see the whole page structure at once. However this causes problems when you want to add an object to the list using javascript. Then I have to keep the old toHtml method and maintain both the main template and the html strings at the same time, so I can output just the HTML for a new object that should be added to the page. So I'm back to the idea of using smaller templates for the objects that make up the page, but I was wondering if there was some easy way of having my cake and eating it too by having one template that shows the whole page but also the mini-templates for smaller objects on the page. Edit: Yes, updating the page is not a problem at all. My concern is with having both maintainability and transparency of the template files. If I have one single template for the whole page, then I must maintain mini-templates of the objects that are shown on the page. If I just have the mini-templates and include them from the higher-level template it becomes more difficult to look at the top-level html and imagine what the end result will look like.

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• how useful is Turing completeness? are neural nets turing complete?

  - by Albert

  While reading some papers about the Turing completeness of recurrent neural nets (for example: Turing computability with neural nets, Hava T. Siegelmann and Eduardo D. Sontag, 1991), I got the feeling that the proof which was given there was not really that practical. For example the referenced paper needs a neural network which neuron activity must be of infinity exactness (to reliable represent any rational number). Other proofs need a neural network of infinite size. Clearly, that is not really that practical. But I started to wonder now if it does make sense at all to ask for Turing completeness. By the strict definition, no computer system nowadays is Turing complete because none of them will be able to simulate the infinite tape. Interestingly, programming language specification leaves it most often open if they are turing complete or not. It all boils down to the question if they will always be able to allocate more memory and if the function call stack size is infinite. Most specification don't really specify this. Of course all available implementations are limited here, so all practical implementations of programming languages are not Turing complete. So, what you can say is that all computer systems are just equally powerful as finite state machines and not more. And that brings me to the question: How useful is the term Turing complete at all? And back to neural nets: For any practical implementation of a neural net (including our own brain), they will not be able to represent an infinite number of states, i.e. by the strict definition of Turing completeness, they are not Turing complete. So does the question if neural nets are Turing complete make sense at all? The question if they are as powerful as finite state machines was answered already much earlier (1954 by Minsky, the answer of course: yes) and also seems easier to answer. I.e., at least in theory, that was already the proof that they are as powerful as any computer.

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• How to make a Global Array?

  - by Wayfarer

  So, I read this post, and it's pretty much exactly what I was looking for. However... it doesn't work. I guess I'm not going to go with the singleton object, but rather making the array in either a Global.h file, or insert it into the _Prefix file. Both times I do that though, I get the error: Expected specifier-qualifier-list before 'static' and it doesn't work. So... I'm not sure how to get it to work, I can remove extern and it works, but I feel like I need that to make it a constant. The end goal is to have this Mutable Array be accessible from any object or any file in my project. Help would be appreciated! This is the code for my Globals.h file: #import <Foundation/Foundation.h> @interface Globals : NSObject { static extern NSMutableArray * myGlobalArray; } @end I don't think I need anything in the implementation file. If I were to put that in the prefix file, the error was the same.

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• Tool for braceless, whitespace sensitive C syntax

  - by Ollie Saunders

  I'm writing some C at the moment and because I like whitespace sensitive syntax, I'd like to write it like this: #include <stdio.h> int main(void) printf("Hello, world!") return 0 Instead of this: #include <stdio.h> int main(void) { printf("Hello, world!"); return 0; } Does anybody know of a tool that will convert the former into the latter? Edit: I've really no interest in arguing with those that think this is a bad idea. By all means continue to think that, you have your reasons. But at least know this: I'm aware Python is a whitespace sensitive language but I have not used it. Why would I? I know Ruby already. Also know: I am not just learning C for the first time and I have used PHP and JavaScript for more than four years, so I am not requesting this out of some personal difficulty, lack of familiarity with block syntax, or dogmatic affiliation. I am also aware of what would be involved in writing one of these and that's not beyond my ability but I don't want this enough to justify spending the time writing one.

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• Good patterns for loose coupling in Java?

  - by Eye of Hell

  Hello. I'm new to java, and while reading documentation so far i can't find any good ways for programming with loose coupling between objects. For majority of languages i know (C++, C#, python, javascript) i can manage objects as having 'signals' (notification about something happens/something needed) and 'slots' (method that can be connected to signal and process notification/do some work). In all mentioned languages i can write something like this: Object1 = new Object1Class(); Object2 = new Object2Class(); Connect( Object1.ItemAdded, Object2.OnItemAdded ); Now if object1 calls/emits ItemAdded, the OnItemAdded method of Object2 will be called. Such loose coupling technique is often referred as 'delegates', 'signal-slot' or 'inversion of control'. Compared to interface pattern, technique mentioned don't need to group signals into some interfaces. Any object's methods can be connected to any delegate as long as signatures match ( C++Qt even extends this by allowing only partial signature match ). So i don't need to write additional interface code for each methods / groups of methods, provide default implementation for interface methods not used etc. And i can't see anything like this in Java :(. Maybe i'm looking a wrong way?

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• Why does my ActivePerl program report 'Sorry. Ran out of threads'?

  - by Zaid

  Tom Christiansen's example code (à la perlthrtut) is a recursive, threaded implementation of finding and printing all prime numbers between 3 and 1000. Below is a mildly adapted version of the script #!/usr/bin/perl # adapted from prime-pthread, courtesy of Tom Christiansen use strict; use warnings; use threads; use Thread::Queue; sub check_prime { my ($upstream,$cur_prime) = @_; my $child; my $downstream = Thread::Queue->new; while (my $num = $upstream->dequeue) { next unless ($num % $cur_prime); if ($child) { $downstream->enqueue($num); } else { $child = threads->create(\&check_prime, $downstream, $num); if ($child) { print "This is thread ",$child->tid,". Found prime: $num\n"; } else { warn "Sorry. Ran out of threads.\n"; last; } } } if ($child) { $downstream->enqueue(undef); $child->join; } } my $stream = Thread::Queue->new(3..shift,undef); check_prime($stream,2); When run on my machine (under ActiveState & Win32), the code was capable of spawning only 118 threads (last prime number found: 653) before terminating with a 'Sorry. Ran out of threads' warning. In trying to figure out why I was limited to the number of threads I could create, I replaced the use threads; line with use threads (stack_size => 1);. The resultant code happily dealt with churning out 2000+ threads. Can anyone explain this behavior?

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• How to reliably replace a library-defined error handler with my own?

  - by sharptooth

  On certain error cases ATL invokes AtlThrow() which is implemented as ATL::AtlThrowImpl() which in turn throws CAtlException. The latter is not very good - CAtlException is not even derived from std::exception and also we use our own exceptions hierarchy and now we will have to catch CAtlException separately here and there which is lots of extra code and error-prone. Looks like it is possible to replace ATL::AtlThrowImpl() with my own handler - define _ATL_CUSTOM_THROW and define AtlThrow() to be the custom handler before including atlbase.h - and ATL will call the custom handler. Not so easy. Some of ATL code is not in sources - it comes compiled as a library - either static or dynamic. We use the static - atls.lib. And... it is compiled in such way that it has ATL::ThrowImpl() inside and some code calling it. I used a static analysis tool - it clearly shows that there're paths on which the old default handler is called. To ensure I even tried to "reimplement" ATL::AtlThrowImpl() in my code. Now the linker says it sees two declarations of ATL::AtlThrowImpl() which I suppose confirms that there's another implementation that can be called by some code. How can I handle this? How do I replace the default handler completely and ensure that the default handler is never called?

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• Extension method using Reflection to Sort

  - by Xavier

  I implemented an extension "MyExtensionSortMethod" to sort collections (IEnumerate). This allows me to replace code such as 'entities.OrderBy( ... ).ThenByDescending( ...)' by 'entities.MyExtensionSortMethod()' (no parameter as well). Here is a sample of implementation: //test function function Test(IEnumerable<ClassA> entitiesA,IEnumerable<ClassB> entitiesB ) { //Sort entitiesA , based on ClassA MySort method var aSorted = entitiesA.MyExtensionSortMethod(); //Sort entitiesB , based on ClassB MySort method var bSorted = entitiesB.MyExtensionSortMethod(); } //Class A definition public classA: IMySort<classA> { .... public IEnumerable<classA> MySort(IEnumerable<classA> entities) { return entities.OrderBy( ... ).ThenBy( ...); } } public classB: IMySort<classB> { .... public IEnumerable<classB> MySort(IEnumerable<classB> entities) { return entities.OrderByDescending( ... ).ThenBy( ...).ThenBy( ... ); } } //extension method public static IEnumerable<T> MyExtensionSortMethod<T>(this IEnumerable<T> e) where T : IMySort<T>, new() { //the extension should call MySort of T Type t = typeof(T); var methodInfo = t.GetMethod("MySort"); //invoke MySort var result = methodInfo.Invoke(new T(), new object[] {e}); //Return return (IEnumerable < T >)result; } public interface IMySort<TEntity> where TEntity : class { IEnumerable<TEntity> MySort(IEnumerable<TEntity> entities); } However, it seems a bit complicated compared to what it does so I was wondering if they were another way of doing it?

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• How to make a good programming interview?

  - by luckyluke

  I am doing interviews with from time to time to recruit some not bad people. And I really think I AM NOT doing to correct Job. I work in a company when We have to do a lot o DB programming, .NET programming, Java programming, so we need people who are open minded and not focused on a particular tech. Afterall language is a notation, You have to understand what is going under the hood. I ask people about their project, ask them some coding questions (believe me a SQL question involving a CROSS JOIN is hard), let them write some code, ask them about oo design, ask them how they update their knowledge, and stay up to date, do they have FUN when they code (at least sometimes). Hell I even give them a coding solution for home (3 hours max) to see how they think and code. And yet my hit rate at hiring junior member (those who live over the initial 3 months) is just about 33%. So my question, how do YOU make the good interviews, because I think my hit rate is to low? Do you have any best-practices(should be at least 60-70%)? p.s. And i noticed that: the best programmers are lazy, but motivated, just being lazy is not enough:) But people who write the best code are attentive to details:)

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• Is using SharePoint as a intranet/extranet portal a good idea?

  - by Rob

  I work for a fortune 500 company in IT and we have developed many systems/applications to do a variety of things. We are in need of some commonality of these applications and a better portal/dashboard/landing page for these applications. So, our customers and employees would log into this portal and see all the "things" that they can do which then link to their own application. This could maybe just iframe in each application inside of this portal to keep brand and navigation consistency. We are trying to decide whether to use SharePoint 2007 or 2010 for this or develop a portal/dashboard of sorts in house. We would like this portal to look and feel very branded to our needs and really not even feel like its using SharePoint (if needed). An example is to provide our own Menu control that drives the navigation if needed. Does anyone have any pros/cons for using SharePoint in such a way? Any advice on implementation (e.g. use 2010, much easier to customize design than 2007, etc)?

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• secure rest API for running user "apps" in an iframe

  - by Brian Armstrong

  I want to let users create "apps" (like Facebook apps) for my website, and I'm trying to figure out the best way to make it secure. I have a REST api i want to run the user apps in an iframe on my own site (not a safe markup language like FBML) I was first looking at oAuth but this seems overkill for my solution. The "apps" don't need to be run on external sites or in desktop apps or anything. The user would stay on my site at all times but see the user submitted "app" through the iframe. So when I call the app the first time through the iframe, I can pass it some variables so it knows which logged in user is using it on my site. It can then use this user session in it's own API calls to customize the display. If the call is passed in the clear, I don't want someone to be able to intercept the session and impersonate the user. Does anyone know a good way to do this or good write up on it? Thanks!

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• Threads, Sockets, and Designing Low-Latency, High Concurrency Servers

  - by lazyconfabulator

  I've been thinking a lot lately about low-latency, high concurrency servers. Specifically, http servers. http servers (fast ones, anyway) can serve thousands of users simultaneously, with very little latency. So how do they do it? As near as I can tell, they all use events. Cherokee and Lighttpd use libevent. Nginx uses it's own event library performing much the same function of libevent, that is, picking a platform optimal strategy for polling events (like kqueue on *bsd, epoll on linux, /dev/poll on Solaris, etc). They all also seem to employ a strategy of multiprocess or multithread once the connection is made - using worker threads to handle the more cpu intensive tasks while another thread continues to listen and handle connections (via events). This is the extent of my understanding and ability to grok the thousand line sources of these applications. What I really want are finer details about how this all works. In examples of using events I've seen (and written) the events are handling both input and output. To this end, do the workers employ some sort of input/output queue to the event handling thread? Or are these worker threads handling their own input and output? I imagine a fixed amount of worker threads are spawned, and connections are lined up and served on demand, but how does the event thread feed these connections to the workers? I've read about FIFO queues and circular buffers, but I've yet to see any implementations to work from. Are there any? Do any use compare-and-swap instructions to avoid locking or is locking less detrimental to event polling than I think? Or have I misread the design entirely? Ultimately, I'd like to take enough away to improve some of my own event-driven network services. Bonus points to anyone providing solid implementation details (especially for stuff like low-latency queues) in C, as that's the language my network services are written in.

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• Database Error Handling: What if You have to Call Outside service and the Transaction Fails?

  - by Ngu Soon Hui

  We all know that we can always wrap our database call in transaction ( with or without a proper ORM), in a form like this: $con = Propel::getConnection(EventPeer::DATABASE_NAME); try { $con->begin(); // do your update, save, delete or whatever here. $con->commit(); } catch (PropelException $e) { $con->rollback(); throw $e; } This way would guarantee that if the transaction fails, the database is restored to the correct status. But the problem is that let's say when I do a transaction, in addition to that transaction, I need to update another database ( an example would be when I update an entry in a column in databaseA, another entry in a column in databaseB must be updated). How to handle this case? Let's say, this is my code, I have three databases that need to be updated ( dbA, dbB, dbc): $con = Propel::getConnection("dbA"); try { $con->begin(); // update to dbA // update to dbB //update to dbc $con->commit(); } catch (PropelException $e) { $con->rollback(); throw $e; } If dbc fails, I can rollback the dbA but I can't rollback dbb. I think this problem should be database independent. And since I am using ORM, this should be ORM independent as well. Update: Some of the database transactions are wrapped in ORM, some are using naked PDO, oledb ( or whatever bare minimum language provided database calls). So my solution has to take care this. Any idea?

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• Why won't my image display??

  - by Josh

  Hello All- Do y'all see anything wrong with my code below? I want my image to appear immediately after page opens but it only opens after the report is run. Please let me know. Thanks. <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="SelectionReport.aspx.cs" Inherits="Geocortex.Essentials.WebFramework.SelectionReportPage" Culture="auto" UICulture="auto" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server"> <title><asp:Literal meta:resourcekey="Title1" runat="server" /></title> </head> <body> <form id="form1" runat="server"> <p> <asp:Image ID="Image1" runat="server" ImageAlign="Left" ImageUrl="~/Images/Loading.gif" style="z-index: 1; left: 254px; top: 15px; position: absolute" /> </p> <gcx:SelectionReportViewer ID="SelectionReportViewer" runat="server" /> </form> </body>

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• what webserver / mod / technique should I use to serve everything from memory?

  - by reinier

  I've lots of lookuptables from which I'll generate my webresponse. I think IIS with Asp.net enables me to keep static lookuptables in memory which I can use to serve up my responses very fast. Are there however also non .net solutions which can do the same? I've looked at fastcgi, but I think this starts X processes, of which anyone can handle Y requests. But the processes are by definition shielded from eachother. I could configure fastcgi to use just 1 process, but does this have scalability implications? anything using PHP or any other interpreted language won't fly because it is also cgi or fastcgi bound right? I understand memcache could be an option, though this would require another (local) socket connection which I'd rather avoid since everything in memory would be much faster. The solution can work under WIndows or Unix... it doesn't matter too much. The only thing which matters is that there will be a lot of requests (100/sec now and growing to 500/sec in a year), and I want to reduce the amount of webservers needed to process it. The current solution is done using PHP and memcache (and the occasional hit to the SQL server backend). Although it is fast (for php anyway), Apache has real problems when the 50/sec is passed. I've put a bounty on this question since I've not seen enough responses to make a wise choice. At the moment I'm considering either Asp.net or fastcgi with C(++).

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• Problem executing script using Python and subprocces.call yet works in Bash

  - by Antoine Benkemoun

  Hello, For the first time, I am asking a little bit of help over here as I am more of a ServerFault person. I am doing some scripting in Python and I've been loving the language so far yet I have this little problem which is keeping my script from working. Here is the code line in question : subprocess.call('xen-create-image --hostname '+nom+' --memory '+memory+' --partitions=/root/scripts/part.tmp --ip '+ip+' --netmask '+netmask+' --gateway '+gateway+' --passwd',shell=True) I have tried the same thing with os.popen. All the variables are correctly set. When I execute the command in question in my regular Linux shell, it works perfectly fine but when I execute it using my Python scripts, I get bizarre errors. I even replaced subprocess.call() by the print function to make sure I am using the exact output of the command. I went looking into environment variables of my shell but they are pretty much the same... I'll post the error I am getting but I'm not sure it's relevant to my problem. Use of uninitialized value $lines[0] in substitution (s///) at /usr/share/perl5/Config/IniFiles.pm line 614. Use of uninitialized value $_ in pattern match (m//) at /usr/share/perl5/Config/IniFiles.pm line 628. I am not a Python expert so I'm most likely missing something here. Thank you in advance for your help, Antoine

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