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• HTML 4, HTML 5, XHTML, MIME types - the definite resource

  - by deceze

  The topics of HTML vs. XHTML and XHTML as text/html vs. XHTML as XHTML are quite complex. Unfortunately it's hard to get a complete picture, since information is spread mostly in bits and pieces around the web or is buried deep in W3C tech jargon. In addition there's some misinformation being circulated. I propose to make this the definite SO resource about the topic, describing the most important aspects of: HTML 4 HTML 5 XHTML 1.0/1.1 as text/html XHTML 1.0/1.1 as XHTML What are the practical implications of each? What are common pitfalls? What is the importance of proper MIME types for each? How do different browsers handle them? I'd like to see one answer per technology. I'm making this a community wiki, so rather than contributing redundant answers, please edit answers to complete the picture. Feel free to start with stubs. Also feel free to edit this question.

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• How to implement YQL paging?

  - by Erik Vold

  I've read the YQL guide, and I keep reviewing http://developer.yahoo.com/yql/guide/yql-o...entables-paging and I have been looking at a few examples, but I'm still left pretty confused how YQL paging works. The problem that I am trying to tackle is creating a YQL open data table for the Mozilla labs Jetpack Gallery's jetpacks pages http://jetpackgallery.mozillalabs.com/jetpacks You flip through the pages of jetpacks with the ?page query variable and there is an order_by query variable. You can only see 10 results per page. Questions: List item Should I use or ? How do I specify the query parameter that indicates the page? in this case it is the 'page' query parameter. I am assuming I should use: <urls><url>http://jetpackgallery.mozillalabs.com/jetpacks</url></urls> is this correct? In the execute element, I will need to extract the details for each jetpack on the page? if so how would I organize that for the response.object? Can anyone provide some help? or perhaps point to a data table that I can look at as a reference? or better documentation on how paging works?

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• How to handle One View with multiple ViewModel and fire different Commands

  - by Naresh

  Hi All, I have senario in which one view and view has binding with multiple ViewModel. Eg. One View displaying Phone Detail and ViewModel as per bellow: Phone basic features- PhoneViewModel, Phone Price Detail- PhoneSubscriptionViewModel, Phone Accessories- PhoneAccessoryViewModel For general properties- PhoneDetailViewModel I have placed View's general properties to PhoneViewModel.Now senario is like this: By default View displays Phone Basic feaures which is bind with ObservationCollection of PhoneViewModel. My view have button - 'View Accessories', onclick of this button one popup screen- in my design I have display/hide Grid and bind it with ObservationCollection of PhoneAccessoryViewModel. Now problem begins- Accessory List also have button 'View Detail' onclick I have to open one popup screen, here also I had placed one Grid and Visible/Hide it. I have bind 'ViewAccessoryDetailCommand' command to 'View Detail' button. And on command execution one function fires and set property which Visible the Popup screen. Using such programming command fires, function calls but the property change not raises and so my view does not display popup. Summary: One View-- ViewModel1--Grid Bind view ViewModel2 --Grid Have Button and Onclick display new Grid which binded with ViewModel3-this Command fires but property not raises. I think there is some problem in my methodology, Please, give your suggetions.

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• How to get decent MySQL driver perfomance in Ruby

  - by Zombies

  I notice that I am getting very poor performance for either or both inserts and queries. The queries themselves are basic and can execute with no delay directly from mysql. The ruby script that I wrote is only 1 thread, so only 1 connection is being used, and never closed unless the script is terminated. Pretty basic, I am just trying to insert a lot of rows. There is a look-up or two to get a surrogate key, or to check for duplicates, but the complexity is just O(n). Also, it isn't like there are millions of records, so again the queries themselves take no time to run. I am using: Ruby 1.9.1 Gem/driver:ruby-mysql 2.9.2 MySQL 5.1.37-1ubuntu5.1 ^ all 32 bit versions on a 32bit ubuntu distro I am getting about 1-2 inserts per second, pretty slow. I know a lot of people will suggest to change drivers, but that means I have some refactoring and resting to do. So I would really appreciate any help, but please if you do recomend that at least say why you do (eg: if you have used ruby-mysql x.x.x before and found another mysql driver to be better).ruby-mysql 2.9.2 What I would like to know: How can I improve performance with ruby-mysql 2.9.2 If and only if I cannot do this with ruby-mysql 2.9.2, what should I do?

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• How can I convert this PHP script to Ruby? (build tree from tabbed string)

  - by Jon Sunrays

  I found this script below online, and I'm wondering how I can do the same thing with a Ruby on Rails setup. So, first off, I ran this command: rails g model Node node_id:integer title:string Given this set up, how can I make a tree from a tabbed string like the following? <?php // Make sure to have "Academia" be root node with nodeID of 1 $data = " Social sciences Anthropology Biological anthropology Forensic anthropology Gene-culture coevolution Human behavioral ecology Human evolution Medical anthropology Paleoanthropology Population genetics Primatology Anthropological linguistics Synchronic linguistics (or Descriptive linguistics) Diachronic linguistics (or Historical linguistics) Ethnolinguistics Sociolinguistics Cultural anthropology Anthropology of religion Economic anthropology Ethnography Ethnohistory Ethnology Ethnomusicology Folklore Mythology Political anthropology Psychological anthropology Archaeology ...(goes on for a long time) "; //echo "Checkpoint 2\n"; $lines = preg_split("/\n/", $data); $parentids = array(0 => null); $db = new PDO("host", 'username', 'pass'); $sql = 'INSERT INTO `TreeNode` SET ParentID = ?, Title = ?'; $stmt = $db->prepare($sql); foreach ($lines as $line) { if (!preg_match('/^([\s]*)(.*)$/', $line, $m)) { continue; } $spaces = strlen($m[1]); //$level = intval($spaces / 4); //assumes four spaces per indent $level = strlen($m[1]); // if data is tab indented $title = $m[2]; $parentid = ($level > 0 ? $parentids[$level - 1] : 1); //All "roots" are children of "Academia" which has an ID of "1"; $rv = $stmt->execute(array($parentid, $title)); $parentids[$level] = $db->lastInsertId(); echo "inserted $parentid - " . $parentid . " title: " . $title . "\n"; } ?>

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• How can I add a link with a UID from a User Reference from a table in Drupal Views

  - by pduncan

  I have the following in Drupal 6: A Master CCK type which contains a User reference field and other fields. There will only be one record per user here. A View of this CCK, shown as a table, with one of the fields being the user ref from the CCK type. This field is initially shown as a user name, linking to the user profile. A Second CCK type which can have several pieces of data about a particular user. A View for this CCK type, displaying information as a table. It takes a user id as an argument (an integer) I want to click on the user name in the master view, and be directed to the detail view for this user. To do this, I tried selecting 'Output this field as a link' on the user field. The thing available for me to replace are: Fields * [field_my_user_ref_uid_1] == Content: User (field_my_user_ref) Arguments * %1 == User: Uid However, the [field_my_user_ref_uid_1] element is replaced by the user name, and %1 seems to get replaced with an empty string. How can I put the user id in here?

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• How to control Dojo FilteringSelect default rendering!?

  - by Nick

  Hi, I have a dojo dijit.filering.select that populates with values from a dojo.data.ItemFileReadStore. Everything is working fine except I would like the filtering select to automatically get populated with the first value in the itemFileReadStore. Currently it is loading them as a list of options that are revealed when you click the down arrow, as per spec. I would instead like filteringSelect to be loaded with the first value. How do I do this? For some reason I cant figure it out. Any help would be hugely appreciated! Kind Regards Nick Frandsen <script type="text/javascript"> function updateOptions(){ var itemId = dijit.byId("item_select").attr("value"); var jsonStore = new dojo.data.ItemFileReadStore({ url: "/options/get-options-json/itemId/" + itemId }); optionSelect.attr("store", jsonStore); } </script> <select dojoType="dijit.form.FilteringSelect" name="option_select" id="option_select" labelAttr="name" required="true" jsId="optionSelect"> </select>

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• Web scraping etiquette

  - by Ash

  I'm considering writing a simple web scraping application to extract information from a website that does not seem to specifically prohibit this. I've checked for other alternatives (eg RSS, web service) to get this information, but there are none available at this stage. Despite this I've also developed/maintained a few websites myself and so I realize that if web scraping is done naively/greedily it can slow things down for other users and generally become a nuisance. So, what etiquette is involved in terms of: Number of requests per second/minute/hour. HTTP User Agent content. HTTP Referer content. HTTP Cache settings. Buffer size for larger files/resources. Legalities and licensing issues. Good tools or design approaches to use. Robots.txt, is this relevant for web scraping or just crawlers/spiders? Compression such as GZip in requests. Update Found this relevant question on Meta: Etiquette of Screen Scaping StackOverflow. Jeff Atwood's answer has some helpful recommendations. Other related StackOverflow questions: Options for html scraping Legalities of screen scraping

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• Can i use a different parser for Axis 1.4?

  - by NishM

  The current SAX parser takes a lot of time (20 minutes) and heap memory(around 400mb) to deserialize the response coming from the soap server as per the logs. Our response XMLs are of average size 4 mb. A part of the log when it runs the applicaiton out of heap is below DEBUG (org.apache.axis.encoding.DeserializationContext) Pushing handler org.apache.axis.message.SOAPHandler@16d22f1 DEBUG (org.apache.axis.i18n.ProjectResourceBundle) org.apache.axis.i18n.resource::handleGetObject(newElem00) DEBUG (org.apache.axis.message.MessageElement) New MessageElement (org.apache.axis.message.MessageElement@112c22) named {}name DEBUG (org.apache.axis.encoding.DeserializationContext) Pushing element name DEBUG (org.apache.axis.utils.NSStack) NSPush (32) DEBUG (org.apache.axis.encoding.DeserializationContext) Exit: DeserializationContext::startElement() DEBUG (org.apache.axis.encoding.DeserializationContext) Enter: DeserializationContext::endElement(, name) DEBUG (org.apache.axis.i18n.ProjectResourceBundle) org.apache.axis.i18n.resource::handleGetObject(popHandler00) DEBUG (org.apache.axis.encoding.DeserializationContext) Popping handler org.apache.axis.message.SOAPHandler@16d22f1 DEBUG (org.apache.axis.utils.NSStack) NSPop (32) DEBUG (org.apache.axis.encoding.DeserializationContext) Popped element stack to org.apache.axis.message.MessageElement:property DEBUG (org.apache.axis.encoding.DeserializationContext) Exit: DeserializationContext::endElement() DEBUG (org.apache.axis.encoding.DeserializationContext) Enter: DeserializationContext::startElement(, value) DEBUG (org.apache.axis.i18n.ProjectResourceBundle) org.apache.axis.i18n.resource::handleGetObject(pushHandler00) DEBUG (org.apache.axis.encoding.DeserializationContext) Pushing handler org.apache.axis.message.SOAPHandler@16880ba DEBUG (org.apache.axis.i18n.ProjectResourceBundle) org.apache.axis.i18n.resource::handleGetObject(newElem00) DEBUG (org.apache.axis.message.MessageElement) New MessageElement (org.apache.axis.message.MessageElement@1db74af) named {}value DEBUG (org.apache.axis.encoding.DeserializationContext) Pushing element value DEBUG (org.apache.axis.utils.NSStack) NSPush (32) DEBUG (org.apache.axis.encoding.DeserializationContext) Exit: DeserializationContext::startElement() DEBUG (org.apache.axis.encoding.DeserializationContext) Enter: DeserializationContext::endElement(, value) DEBUG (org.apache.axis.i18n.ProjectResourceBundle) org.apache.axis.i18n.resource::handleGetObject(popHandler00) DEBUG (org.apache.axis.encoding.DeserializationContext) Popping handler org.apache.axis.message.SOAPHandler@16880ba DEBUG (org.apache.axis.utils.NSStack) NSPop (32) I cannot use Axis2 because of technical reasons. I have tried using HTTP Commons client instead of HTTP client but the response time remains the same. How can i link a different parser(example xerces 2.10.0 or xstream 1.3.1?) to Axis 1.4 framework in this context so that memory management and response time is favorable?.

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• file layout and setuptools configuration for the python bit of a multi-language library

  - by dan mackinlay

  So we're writing a full-text search framework MongoDb. MongoDB is pretty much javascript-native, so we wrote the javascript library first, and it works. Now I'm trying to write a python framework for it, which will be partially in python, but partially use those same stored javascript functions - the javascript functions are an intrinsic part of the library. On the other hand, the javascript framework does not depend on python. since they are pretty intertwined it seems like it's worthwhile keeping them in the same repository. I'm trying to work out a way of structuring the whole project to give the javascript and python frameworks equal status (maybe a ruby driver or whatever in the future?), but still allow the python library to install nicely. Currently it looks like this: (simplified a little) javascript/jstest/test1.js javascript/mongo-fulltext/search.js javascript/mongo-fulltext/util.js python/docs/indext.rst python/tests/search_test.py python/tests/__init__.py python/mongofulltextsearch/__init__.py python/mongofulltextsearch/mongo_search.py python/mongofulltextsearch/util.py python/setup.py I've skipped out a few files for simplicity, but you get the general idea; it' a pretty much standard python project... except that it depends critcally ona whole bunch of javascript which is stored in a sibling directory tree. What's the preferred setup for dealing with this kind of thing when it comes to setuptools? I can work out how to use package_data etc to install data files that live inside my python project as per the setuptools docs. The problem is if i want to use setuptools to install stuff, including the javascript files from outside the python code tree, and then also access them in a consistent way when I'm developing the python code and when it is easy_installed to someone's site. Is that supported behaviour for setuptools? Should i be using paver or distutils2 or Distribute or something? (basic distutils is not an option; the whole reason I'm doing this is to enable requirements tracking) How should i be reading the contents of those files into python scripts?

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• Codeigniter image manipulation class rotates image during resize

  - by someoneinomaha

  I'm using Codeigniter's image manipulation library to re-size an uploaded image to three sizes, small, normal and large. The re-sizing is working great. However, if I'm resizing a vertical image, the library is rotating the image so it's horizontal. These are the config settings I have in place: $this->resize_config['image_library'] = 'gd2'; $this->resize_config['source_image'] = $this->file_data['full_path']; $this->resize_config['maintain_ratio'] = TRUE; // These change based on the type (small, normal, large) $this->resize_config['new_image'] = './uploads/large/'.$this->new_file_name.'.jpg'; $this->resize_config['width'] = 432; $this->resize_config['height'] = 288; I'm not setting the master_dim property because the default it set to auto, which is what I want. My assumption is that the library would take a vertical image, see that the height is greater than the width and translate the height/width config appropriately so the image remains vertical. What is happening (apparently) is that the library is rotating the image when it is vertical and sizing it per the configuration. This is the code in place I have to do the actual re-sizing: log_message('debug', 'attempting '.$size.' photo resize'); $this->CI->load->library('image_lib'); $this->CI->image_lib->initialize($this->resize_config); if ($this->CI->image_lib->resize()) { $return_value = TRUE; log_message('debug', $size.' photo resize successful'); } else { $this->errors[] = $this->CI->image_lib->display_errors(); log_message('debug', $size.' photo resize failed'); } $this->CI->image_lib->clear(); return $return_value;

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• Memory leak while asynchronously loading BitmapSource images

  - by harry

  I have a fair few images that I'm loading into a ListBox in my WPF application. Originally I was using GDI to resize the images (the originals take up far too much memory). That was fine, except they were taking about 400ms per image. Not so fine. So in search of another solution I found a method that uses TransformedBitmap (which inherits from BitmapSource). That's great, I thought, I can use that. Except I'm now getting memory leaks somewhere... I'm loading the images asynchronously using a BackgroundWorker like so: BitmapSource bs = ImageUtils.ResizeBitmapSource(ImageUtils.GetImageSource(photo.FullName)); //BitmapSource bs = ImageUtils.GetImageSource(photo.FullName); bs.Freeze(); this.dispatcher.Invoke(new Action(() => { photo.Source = bs; })); GetImageSource just gets the Bitmap from the path and then converts to BitmapSource. Here's the code snippet for ResizeBitmapSource: const int thumbnailSize = 200; int width; int height; if (bs.Width > bs.Height) { width = thumbnailSize; height = (int)(bs.Height * thumbnailSize / bs.Width); } else { height = thumbnailSize; width = (int)(bs.Width * thumbnailSize / bs.Height); } BitmapSource tbBitmap = new TransformedBitmap(bs, new ScaleTransform(width / bs.Width, height / bs.Height, 0, 0)); return tbBitmap; That code is essentially the code from: http://rongchaua.net/blog/c-wpf-fast-image-resize/ Any ideas what could be causing the leak?

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• HttpModule with ASP.NET MVC not being called

  - by mgroves

  I am trying to implement a session-per-request pattern in an ASP.NET MVC 2 Preview 1 application, and I've implemented an IHttpModule to help me do this: public class SessionModule : IHttpModule { public void Init(HttpApplication context) { context.Response.Write("Init!"); context.EndRequest += context_EndRequest; } // ... etc... } And I've put this into the web.config: <system.web> <httpModules> <add name="SessionModule" type="MyNamespace.SessionModule" /> </httpModules> <system.webServer> <modules runAllManagedModulesForAllRequests="true"> <remove name="SessionModule" /> <add name="SessionModule" type="MyNamespace.SessionModule" /> </modules> However, "Init!" never gets written to the page (I'm using the built-in VS web server, Cassini). Additionally, I've tried putting breakpoints in the SessionModule but they never break. What am I missing?

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• java RMI newbie-- some basic questions about SSL and auth/.rate limiting an RMI service

  - by Arvind

  I am trying to work to secure a java based RMI service using SSL. I have some basic questions about the capabilities of using SSL. Specifically, from what I understand, the client and server connecting via SSL will need to have appropriate credential certificates in both client and server, for a client to be granted access to the server. Am I correct in my understanding? Also, what I want to know is, can a person who is already using my RMI service and has access to a client machine , make a copy of the certificate in the client machine to other client machines-- and then invoke my RMI service from those other machines as well? How do I prevent such a situation from occurring? I mean, in a REST API you can use OAuth authentication, can we have some kind of authentication in an RMI Service? Also, can I possibly limit usage of the RMI service? For eg, a specific client may be allowed to make only 5000 calls per day to my RMI service, and if he makes more calls the calls occurring after the 5000 calls limit are all denied? How do I do such rate limiting and/or authentication for my RMI Service?

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• While porting a windows application to web, is it better to stick to conventional web technologies o

  - by Kabeer

  Hello. The web based application I am working on currently is a port from a windows application. This application is very data intensive. There are scores of modules and each of these modules have number of forms (data entry screens) and reports whereas the forms have many many fields and likewise the reports. I have been trying to identify the most suitable architecture for the presentation tier. There are many functions that are not very easily portable, for example printing (this too is very complex). For most of the others, I am planning to us "Ext JS" library which looks like capable of handling about 70% of complexity out of the box while for the remaining I would be custom coding or extending Ext JS. Having said that (sorry for being so descriptive), I wonder, if this is an Intranet application, why not port the entire application to SilverLight? While I am good at .Net, I'm somewhat alien to SilverLight. Considering I know my target audience and that the software will be used per seat license, would it be better to ride on SilverLight or is it better to stick to conventional web (XHTML, JS, CSS, etc)? Further, I have to support multiple devices in future and considering that SilverLight plug-ins for many devices are yet not out, would it be a risk?

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• File Format Conversion to TIFF. Some issues???

  - by Nains

  I'm having a proprietary image format SNG( a proprietary format) which is having a countinous array of Image data along with Image meta information in seperate HDR file. Now I need to convert this SNG format to a Standard TIFF 6.0 Format. So I studied the TIFF format i.e. about its Header, Image File Directories( IFD's) and Stripped Image Data. Now I have few concerns about this conversion. Please assist me. SNG Continous Data vs TIFF Stripped Data: Should I convert SNG Data to TIFF as a continous data in one Strip( data load/edit time problem?) OR make logical StripOffsets of the SNG Image data. SNG Data Header uses only necessary Meta Information, thus while converting the SNG to TIFF, some information can’t be retrieved such as NewSubFileType, Software Tag etc. So this raises a concern that after conversion whether any missing directory information such as NewSubFileType, Software Tag etc is necessary and sufficient condition for TIFF File. Encoding of each pixel component of RGB Sample in SNG data: Here each SNG Image Data Strip per Pixel component is encoded as: Out^[i] := round( LineBuffer^[i * 3] * **0.072169** + LineBuffer^[i * 3 + 1] * **0.715160** + LineBuffer^[i * 3+ 2]* **0.212671**); Only way I deduce from it is that each Pixel is represented with 3 RGB component and some coefficient is multiplied with each component to make the SNG Viewer work RGB color information of SNG Image Data. (Developer who earlier work on this left, now i am following the trace :)) Thus while converting this to TIFF, the decoding the same needs to be done. This raises a concern that the how RBG information in TIFF is produced, or better do we need this information?. Please assist...

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• Polymorphic NHibernate mappings

  - by Ben Aston

  I have an interface IUserLocation and a concrete type UserLocation. When I use ICriteria, specifying the interface IUserLocation, I want NHibernate to instantiate a collection of the concrete UserLocation type. I have created an HBM mapping file using the table per concrete type strategy (shown below). However, when I query NHibernate using ICriteria I get: NHibernate cannot instantiate abstract class or interface MyNamespace.IUserLocation Can anyone see why this is? (source code for the relevant bit of NHibernate here (I think)) My ICriteria: var filter = DetachedCriteria.For<IUserLocation>() .Add(Restrictions.Eq("UserId", userId)); return filter.GetExecutableCriteria(UoW.Session) .List<IUserLocation>(); My mapping file: <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-lazy="true"> <class xmlns="urn:nhibernate-mapping-2.2" name="MyNamespace.IUserLocation,MyAssembly" abstract="true" table="IUserLocations"> <composite-id> <key-property name="UserId" column="UserId" type="System.Guid"></key-property> <key-many-to-one name="Location" column="LocationId" class="MyNamespace.ILocation,MyAssembly"></key-many-to-one> </composite-id> <union-subclass table="UserLocations" name="MyNamespace2.UserLocation,MyAssembly2"> <property name="IsAdmin" /> </union-subclass> </class> </hibernate-mapping>

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• Could CouchDB benefit significantly from the use of BERT instead of JSON?

  - by Victor Rodrigues

  I appreciate a lot CouchDB attempt to use universal web formats in everything it does: RESTFUL HTTP methods in every interaction, JSON objects, javascript code to customize database and documents. CouchDB seems to scale pretty well, but the individual cost to make a request usually makes 'relational' people afraid of. Many small business applications should deal with only one machine and that's all. In this case the scalability talk doesn't say too much, we need more performance per request, or people will not use it. BERT (Binary ERlang Term http://bert-rpc.org/ ) has proven to be a faster and lighter format than JSON and it is native for Erlang, the language in which CouchDB is written. Could we benefit from that, using BERT documents instead of JSON ones? I'm not saying just for retrieving in views, but for everything CouchDB does, including syncing. And, as a consequence of it, use Erlang functions instead of javascript ones. This would modify some original CouchDB principles, because today it is very web oriented. Considering I imagine few people would make their database API public and usually its data is accessed by the users through an application, it would be a good deal to have the ability to configure CouchDB for working faster. HTTP+JSON calls could still be handled by CouchDB, considering an extra cost in these cases because of parsing.

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• Reachability sometimes fails, even when we do have an internet connection

  - by stoutyhk

  Hi I've searched but can't see a similar question. I've added a method to check for an internet connection per the Reachability example. It works most of the time, but when installed on the iPhone, it quite often fails even when I do have internet connectivity (only when on 3G/EDGE - WiFi is OK). Basically the code below returns NO. If I switch to another app, say Mail or Safari, and connect, then switch back to the app, then the code says the internet is reachable. Kinda seems like it needs a 'nudge'. Anyone seen this before? Any ideas? Many thanks James + (BOOL) doWeHaveInternetConnection{ BOOL success; // google should always be up right?! const char *host_name = [@"google.com" cStringUsingEncoding:NSASCIIStringEncoding]; SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(NULL, host_name); SCNetworkReachabilityFlags flags; success = SCNetworkReachabilityGetFlags(reachability, &flags); BOOL isAvailable = success && (flags & kSCNetworkFlagsReachable) && !(flags & kSCNetworkFlagsConnectionRequired); if (isAvailable) { NSLog(@"Google is reachable: %d", flags); }else{ NSLog(@"Google is unreachable"); } return isAvailable; }

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• Can't get any speedup from parallelizing Quicksort using Pthreads

  - by Murat Ayfer

  I'm using Pthreads to create a new tread for each partition after the list is split into the right and left halves (less than and greater than the pivot). I do this recursively until I reach the maximum number of allowed threads. When I use printfs to follow what goes on in the program, I clearly see that each thread is doing its delegated work in parallel. However using a single process is always the fastest. As soon as I try to use more threads, the time it takes to finish almost doubles, and keeps increasing with number of threads. I am allowed to use up to 16 processors on the server I am running it on. The algorithm goes like this: Split array into right and left by comparing the elements to the pivot. Start a new thread for the right and left, and wait until the threads join back. If there are more available threads, they can create more recursively. Each thread waits for its children to join. Everything makes sense to me, and sorting works perfectly well, but more threads makes it slow down immensely. I tried setting a minimum number of elements per partition for a thread to be started (e.g. 50000). I tried an approach where when a thread is done, it allows another thread to be started, which leads to hundreds of threads starting and finishing throughout. I think the overhead was way too much. So I got rid of that, and if a thread was done executing, no new thread was created. I got a little more speedup but still a lot slower than a single process. The code I used is below. http://pastebin.com/UaGsjcq2 Does anybody have any clue as to what I could be doing wrong?

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• Which Computer Organization & Architecture book is good for me?

  - by claws

  I'm always interested in learning the inner working of things. I started with C programming and then learnt Operating systems (from stallings) and then linkers & loaders and then assembly language after reading these now I want to go into little more depth. Computer Architecture. I feel that makes everything clear. As per SO archives these are the two good books: Computer Architecture: A Quantitative Approach, 4th Edition Computer Organization and Design, Fourth Edition, ~ David A. Patterson, John L. Hennessy But I've browsed through the contents of these books and found that they don't exactly meet my needs. I want to learn more about caches, Memory Management Unit , mapping b/w virtual memory & physical memory I'm no way interested in other ISAs like MIPS etc.. I'm IA32 and X86-64 fan and I want to stick to it. I'm not a hardware developer I don't want to details like circuit diagrams or How is L1, L2 & L3 caches are implemented? I want to know the parallel processing technologies like HyperThreading at the architecture level but again I don't want to design them. I liked the table of Contents of - Computer Architecture: A Quantitative Approach, 4th Edition but Quantitave Approach? Seriously?? I want to know the details of current technologies and I dont want to spend reading 200 pages of outdated old technologies ( I experienced this while learning ASM}

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• WCF for a shared data access

  - by Audrius

  Hi all, I have a little experience with WCF and would like to get your opinion/suggestion on how the following problem can be solved: A web service needs to be accessible from multiple clients simultaneously and service needs to return a result from a shared data set. The concrete project I'm working on has to store a list of IP addresses/ranges. This list will be queried by a bunch of web servers for a validation purposes and we speak of a couple of thousand or more queries per minute. My initial draft approach was to use Windows service as a WCF host with service contract implementing class that is decorated with ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Multiple) that has a list object and a custom locking for accessing it. So basically I have a WCF service singleton with a list = shared data - multiple clients. What I do not like about it is that data and communication layers are merged into one and performance wise this doesn't feel "right". What I really really (- want is Windows service running an instance of IP list holding container class object, a second service running WCF service contract implementation and a way the latter querying the former in a nice way with a minimal blocking. Using another WCF channel would not really take me far away from the initial draft implementation or would it? What approach would you take? Project is still in a very early stage so complete design re-do is not out of question. All ideas are appreciated. Thanks! UPDATE: The data set will be changed dynamically. Web service will have a separate method to add IP or IP range and on top of that there will be a scheduled task that will trigger data cleanup every 10-15 minutes according to some rules. UPDATE 2: a separate benchmark project will be kicked up that should use MSSQL as a data backend (instead on in-memory list).

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• Database structure and source control - best practice

  - by Paddy

  Background I came from several years working in a company where all the database objects were stored in source control, one file per object. We had a list of all the objects that was maintained when new items were added (to allow us to have scripts run in order and handle dependencies) and a VB script that ran to create one big script for running against the database. All the tables were 'create if not exists' and all the SP's etc. were drop and recreate. Up to the present and I am now working in a place where the database is the master and there is no source control for DB objects, but we do use redgate's tools for updating our production database (SQL compare), which is very handy, and requires little work. Question How do you handle your DB objects? I like to have them under source control (and, as we're using GIT, I'd like to be able to handle merge conflicts in the scripts, rather than the DB), but I'm going to be pressed to get past the ease of using SQL compare to update the database. I don't really want to have us updating scripts in GIT and then using SQL compare to update the production database from our DEV DB, as I'd rather have 'one version of the truth', but I don't really want to get into re-writing a custom bit of software to bundle the whole lot of scripts together. I think that visual studio database edition may do something similar to this, but I'm not sure if we will have the budget for it. I'm sure that this has been asked to death, but I can't find anything that seems to quite have the answer I'm looking for. Similar to this, but not quite the same: http://stackoverflow.com/questions/340614/what-are-the-best-practices-for-database-scripts-under-code-control

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• CQRS - The query side

  - by mattcodes

  A lot of the blogsphere articles related to CQRS (command query repsonsibility) seperation seem to imply that all screens/viewmodels are flat. e.g. Name, Age, Location Of Birth etc.. and thus the suggestion that implementation wise we stick them into fast read source etc.. single table per view mySQL etc.. and pull them out with something like primitive SqlDataReader, kick that nasty nhibernate ORM etc.. However, whilst I agree that domain models dont mapped well to most screens, many of the screens that I work with are more dimensional, and Im sure this is pretty common in LOB apps. So my question is how are people handling screen where by for example it displays a summary of customer details and then a list of their orders with a [more detail] link etc.... I thought about keeping with the straight forward SQL query to the Query Database breaking off the outer join so can build a suitable ViewModel to View but it seems like overkill? Alternatively (this is starting to feel yuck) in CustomerSummaryView table have a text/big (whatever the type is in your DB) column called Orders, and the columns for the Order summary screen grid are seperated by , and rows by |. Even with XML datatype it still feeel dirty. Any thoughts on an optimal practice?

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• Mixing NIO with IO

  - by Steffen Heil

  Hi Usually you have a single bound tcp port and several connections on these. At least there are usually more connections as bound ports. My case is different: I want to bind a lot of ports and usually have no (or at least very few) connections. So I want to use NIO to accept the incoming connections. However, I need to pass the accepted connections to the existing jsch ssh library. That requires IO sockets instead of NIO sockets, it spawns one (or two) thread(s) per connection. But that's fine for me. Now, I thought that the following lines would deliver the very same result: Socket a = serverSocketChannel.accept().socket(); Socket b = serverSocketChannel.socket().accep(); SocketChannel channel = serverSocketChannel.accpet(); channel.configureBlocking( true ); Socket c = channel.socket(); Socket d = serverSocket.accept(); However the getInputStream() and getOutputStream() functions of the returned sockets seem to work different. Only if the socket was accepted using the last call, jsch can work with it. In the first three cases, it fails (and I am sorry: I don't know why). So is there a way to convert such a socket? Regards, Steffen

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