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  • Need help with joins in sqlalchemy

    - by Steve
    I'm new to Python, as well as SQL Alchemy, but not the underlying development and database concepts. I know what I want to do and how I'd do it manually, but I'm trying to learn how an ORM works. I have two tables, Images and Keywords. The Images table contains an id column that is its primary key, as well as some other metadata. The Keywords table contains only an id column (foreign key to Images) and a keyword column. I'm trying to properly declare this relationship using the declarative syntax, which I think I've done correctly. Base = declarative_base() class Keyword(Base): __tablename__ = 'Keywords' __table_args__ = {'mysql_engine' : 'InnoDB'} id = Column(Integer, ForeignKey('Images.id', ondelete='CASCADE'), primary_key=True) keyword = Column(String(32), primary_key=True) class Image(Base): __tablename__ = 'Images' __table_args__ = {'mysql_engine' : 'InnoDB'} id = Column(Integer, primary_key=True, autoincrement=True) name = Column(String(256), nullable=False) keywords = relationship(Keyword, backref='image') This represents a many-to-many relationship. One image can have many keywords, and one keyword can relate back to many images. I want to do a keyword search of my images. I've tried the following with no luck. Conceptually this would've been nice, but I understand why it doesn't work. image = session.query(Image).filter(Image.keywords.contains('boy')) I keep getting errors about no foreign key relationship, which seems clearly defined to me. I saw something about making sure I get the right 'join', and I'm using 'from sqlalchemy.orm import join', but still no luck. image = session.query(Image).select_from(join(Image, Keyword)).\ filter(Keyword.keyword == 'boy') I added the specific join clause to the query to help it along, though as I understand it, I shouldn't have to do this. image = session.query(Image).select_from(join(Image, Keyword, Image.id==Keyword.id)).filter(Keyword.keyword == 'boy') So finally I switched tactics and tried querying the keywords and then using the backreference. However, when I try to use the '.images' iterating over the result, I get an error that the 'image' property doesn't exist, even though I did declare it as a backref. result = session.query(Keyword).filter(Keyword.keyword == 'boy').all() I want to be able to query a unique set of image matches on a set of keywords. I just can't guess my way to the syntax, and I've spent days reading the SQL Alchemy documentation trying to piece this out myself. I would very much appreciate anyone who can point out what I'm missing.

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  • Parallel Task Library WaitAny Design

    - by colithium
    I've just begun to explore the PTL and have a design question. My Scenario: I have a list of URLs that each refer to an image. I want each image to be downloaded in parallel. As soon as at least one image is downloaded, I want to execute a method that does something with the downloaded image. That method should NOT be parallelized -- it should be serial. I think the following will work but I'm not sure if this is the right way to do it. Because I have separate classes for collecting the images and for doing "something" with the collected images, I end up passing around an array of Tasks which seems wrong since it exposes the inner workings of how images are retrieved. But I don't know a way around it. In reality there is more to both of these methods but that's not important for this. Just know that they really shouldn't be lumped into one large method that both retrieves and does something with the image. Task<Image>[] downloadTasks = collector.RetrieveImages(listOfURLs); for (int i = 0; i < listOfURLs.Count; i++) { //Wait for any of the remaining downloads to complete int completedIndex = Task<Image>.WaitAny(downloadTasks); Image completedImage = downloadTasks[completedIndex].Result; //Now do something with the image (this "something" must happen serially) } /////////////////////////////////////////////////// public Task<Image>[] RetrieveImages(List<string> urls) { Task<Image>[] tasks = new Task<Image>[urls.Count]; int index = 0; foreach (string url in urls) { string lambdaVar = url; //Required... Bleh tasks[index] = Task<Image>.Factory.StartNew(() => { using (WebClient client = new WebClient()) { //TODO: Replace with live image locations string fileName = String.Format("{0}.png", i); client.DownloadFile(lambdaVar, Path.Combine(Application.StartupPath, fileName)); } return Image.FromFile(Path.Combine(Application.StartupPath, fileName)); }, TaskCreationOptions.LongRunning | TaskCreationOptions.AttachedToParent); index++; } return tasks; }

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  • Carrierwave upload to a tmp dir before saving to database

    - by user827570
    I'm trying to build a visual editor where users can click an image they are presented with an image upload form once the upload is done I use ajax to return the image and insert it back into the page. But the above method inserts the image straight into the database but I want users to be able to visualize the image before the image is inserted into the database. So I was wondering if the image using carrierwave could be uploaded to a temp location, sent back to the user and then when the user saves the page the image is moved into the permanent location. Here's what I have so far. def edit_image @page = Page.find(1) @page.update_attributes(params[:page]) @page.save return :text => @page.file end But this is what I want to achieve def temp_image #uploads received image to a temp location #returns image to the user end And once the user clicks save def save #moves the file in the temp folder to the permanent location end Cheers

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  • ASp.Net Mvc 1.0 Dynamic Images Returned from Controller taking 154 seconds+ to display in IE8, firef

    - by julian guppy
    I have a curious problem with IE, IIS 6.0 dynamic PNG files and I am baffled as to how to fix.. Snippet from Helper (this returns the URL to the view for requesting the images from my Controller. string url = LinkBuilder.BuildUrlFromExpression(helper.ViewContext.RequestContext, helper.RouteCollection, c = c.FixHeight(ir.Filename, ir.AltText, "FFFFFF")); url = url.Replace("&", "&"); sb.Append(string.Format("<removed id=\"TheImage\" src=\"{0}\" alt=\"\" /", url)+Environment.NewLine); This produces a piece of html as follows:- img id="TheImage" src="/ImgText/FixHeight?sFile=Images%2FUser%2FJulianGuppy%2FMediums%2Fconservatory.jpg&backgroundColour=FFFFFF" alt="" / brackets missing because i cant post an image... even though I dont want to post an image I jsut want to post the markup... sigh Snippet from Controller ImgTextController /// <summary> /// This function fixes the height of the image /// </summary> /// <param name="sFile"></param> /// <param name="alternateText"></param> /// <param name="backgroundColour"></param> /// <returns></returns> [AcceptVerbs(HttpVerbs.Get)] public ActionResult FixHeight(string sFile, string alternateText, string backgroundColour) { #region File if (string.IsNullOrEmpty(sFile)) { return new ImgTextResult(); } // MVC specific change to prepend the new directory if (sFile.IndexOf("Content") == -1) { sFile = "~/Content/" + sFile; } // open the file System.Drawing.Image img; try { img = System.Drawing.Image.FromFile(Server.MapPath(sFile)); } catch { img = null; } // did we fail? if (img == null) { return new ImgTextResult(); } #endregion File #region Width // Sort out the width from the image passed to me Int32 nWidth = img.Width; #endregion Width #region Height Int32 nHeight = img.Height; #endregion Height // What is the ideal height given a width of 2100 this should be 1400. var nIdealHeight = (int)(nWidth / 1.40920096852); // So is the actual height of the image already greater than the ideal height? Int32 nSplit; if (nIdealHeight < nHeight) { // Yes, do nothing, well i need to return the iamge... nSplit = 0; } else { // rob wants to not show the white at the top or bottom, so if we were to crop the image how would be do it // 1. Calculate what the width should be If we dont adjust the heigt var newIdealWidth = (int)(nHeight * 1.40920096852); // 2. This newIdealWidth should be smaller than the existing width... so work out the split on that Int32 newSplit = (nWidth - newIdealWidth) / 2; // 3. Now recrop the image using 0-nHeight as the height (i.e. full height) // but crop the sides so that its the correct aspect ration var newRect = new Rectangle(newSplit, 0, newIdealWidth, nHeight); img = CropImage(img, newRect); nHeight = img.Height; nWidth = img.Width; nSplit = 0; } // No, so I want to place this image on a larger canvas and we do this by Creating a new image to be the size that we want System.Drawing.Image canvas = new Bitmap(nWidth, nIdealHeight, PixelFormat.Format24bppRgb); Graphics g = Graphics.FromImage(canvas); #region Color // Whilst we can set the background colour we shall default to white if (string.IsNullOrEmpty(backgroundColour)) { backgroundColour = "FFFFFF"; } Color bc = ColorTranslator.FromHtml("#" + backgroundColour); #endregion Color // Filling the background (which gives us our broder) Brush backgroundBrush = new SolidBrush(bc); g.FillRectangle(backgroundBrush, -1, -1, nWidth + 1, nIdealHeight + 1); // draw the image at the position var rect = new Rectangle(0, nSplit, nWidth, nHeight); g.DrawImage(img, rect); return new ImgTextResult { Image = canvas, ImageFormat = ImageFormat.Png }; } My ImgTextResult is a class that returns an Action result for me but embedding the image from a memory stream into the response.outputstream. snippet from my ImageResults /// <summary> /// Execute the result /// </summary> /// <param name="context"></param> public override void ExecuteResult(ControllerContext context) { // output context.HttpContext.Response.Clear(); context.HttpContext.Response.ContentType = "image/png"; try { var memStream = new MemoryStream(); Image.Save(memStream, ImageFormat.Png); context.HttpContext.Response.BinaryWrite(memStream.ToArray()); context.HttpContext.Response.Flush(); context.HttpContext.Response.Close(); memStream.Dispose(); Image.Dispose(); } catch (Exception ex) { string a = ex.Message; } } Now all of this works locally and lovely, and indeed all of this works on my production server BUT Only for Firefox, Safari, Chrome (and other browsers) IE has a fit and decides that it either wont display the image or it does display the image after approx 154seconds of waiting..... I have made sure my HTML is XHTML compliant, I have made sure I am getting no Routing errors or crashes in my event log on the server.... Now obviously I have been a muppet and have done something wrong... but what I cant fathom is why in development all works fine, and in production all non IE browsers also work fine, but IE 8 using IIS 6.0 production server is having some kind of problem in returning this PNG and I dont have an error to trace... so what I am looking for is guidance as to how I can debug this problem.

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  • Rails / JBuilder - Entity array with has_many attributes

    - by seufagner
    I have two models, Person and Image and I want return an json array of Persons with your Images. But I dont want return all Image attributes, but produces a different result. Code below: class Person < ActiveRecord::Base has_many :images, as: :imageable validates :name, presence: true accepts_nested_attributes_for :images, :reject_if => lambda { |img| img['asset'].blank? } end class Image < ActiveRecord::Base belongs_to :imageable, polymorphic: true mount_uploader :asset, ImageUploader validates :asset, presence: true end zzz.jbuilder.json template json.persons(@rodas, :id, :name, :images) json produced: { "rodas": [{ "id": 4, "name": "John", "images": [ { "asset": { "url": "/uploads/image/xxxx.png" } }, { "asset": { "url": "/uploads/image/yyyyy.jpeg" } } ]}, { "id": 19, "name": "Mary", "images": [ { "asset": { "url": "/uploads/image/kkkkkkk.png" } } ] }] } I want something like: { "rodas": [ { "id": 4, "name": "John", "images": [ "/uploads/image/xxxx.png" , "/uploads/image/yyyy.jpeg" ] }, { "id": 10, "name": "Mary", "images": [ "/uploads/image/dddd.png" , "/uploads/image/xxxx.jpeg" ] } ]}

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  • can someone help me fix my code?

    - by user267490
    Hi, I have this code I been working on but I'm having a hard time for it to work. I did one but it only works in php 5.3 and I realized my host only supports php 5.0! do I was trying to see if I could get it to work on my sever correctly, I'm just lost and tired lol <?php //Temporarily turn on error reporting @ini_set('display_errors', 1); error_reporting(E_ALL); // Set default timezone (New PHP versions complain without this!) date_default_timezone_set("GMT"); // Common set_time_limit(0); require_once('dbc.php'); require_once('sessions.php'); page_protect(); // Image settings define('IMG_FIELD_NAME', 'cons_image'); // Max upload size in bytes (for form) define ('MAX_SIZE_IN_BYTES', '512000'); // Width and height for the thumbnail define ('THUMB_WIDTH', '150'); define ('THUMB_HEIGHT', '150'); ?> <!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" xml:lang="en"> <head> <title>whatever</title> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> <style type="text\css"> .validationerrorText { color:red; font-size:85%; font-weight:bold; } </style> </head> <body> <h1>Change image</h1> <?php $errors = array(); // Process form if (isset($_POST['submit'])) { // Get filename $filename = stripslashes($_FILES['cons_image']['name']); // Validation of image file upload $allowedFileTypes = array('image/gif', 'image/jpg', 'image/jpeg', 'image/png'); if ($_FILES[IMG_FIELD_NAME]['error'] == UPLOAD_ERR_NO_FILE) { $errors['img_empty'] = true; } elseif (($_FILES[IMG_FIELD_NAME]['type'] != '') && (!in_array($_FILES[IMG_FIELD_NAME]['type'], $allowedFileTypes))) { $errors['img_type'] = true; } elseif (($_FILES[IMG_FIELD_NAME]['error'] == UPLOAD_ERR_INI_SIZE) || ($_FILES[IMG_FIELD_NAME]['error'] == UPLOAD_ERR_FORM_SIZE) || ($_FILES[IMG_FIELD_NAME]['size'] > MAX_SIZE_IN_BYTES)) { $errors['img_size'] = true; } elseif ($_FILES[IMG_FIELD_NAME]['error'] != UPLOAD_ERR_OK) { $errors['img_error'] = true; } elseif (strlen($_FILES[IMG_FIELD_NAME]['name']) > 200) { $errors['img_nametoolong'] = true; } elseif ( (file_exists("\\uploads\\{$username}\\images\\banner\\{$filename}")) || (file_exists("\\uploads\\{$username}\\images\\banner\\thumbs\\{$filename}")) ) { $errors['img_fileexists'] = true; } if (! empty($errors)) { unlink($_FILES[IMG_FIELD_NAME]['tmp_name']); //cleanup: delete temp file } // Create thumbnail if (empty($errors)) { // Make directory if it doesn't exist if (!is_dir("\\uploads\\{$username}\\images\\banner\\thumbs\\")) { // Take directory and break it down into folders $dir = "uploads\\{$username}\\images\\banner\\thumbs"; $folders = explode("\\", $dir); // Create directory, adding folders as necessary as we go (ignore mkdir() errors, we'll check existance of full dir in a sec) $dirTmp = ''; foreach ($folders as $fldr) { if ($dirTmp != '') { $dirTmp .= "\\"; } $dirTmp .= $fldr; mkdir("\\".$dirTmp); //ignoring errors deliberately! } // Check again whether it exists if (!is_dir("\\uploads\\$username\\images\\banner\\thumbs\\")) { $errors['move_source'] = true; unlink($_FILES[IMG_FIELD_NAME]['tmp_name']); //cleanup: delete temp file } } if (empty($errors)) { // Move uploaded file to final destination if (! move_uploaded_file($_FILES[IMG_FIELD_NAME]['tmp_name'], "/uploads/$username/images/banner/$filename")) { $errors['move_source'] = true; unlink($_FILES[IMG_FIELD_NAME]['tmp_name']); //cleanup: delete temp file } else { // Create thumbnail in new dir if (! make_thumb("/uploads/$username/images/banner/$filename", "/uploads/$username/images/banner/thumbs/$filename")) { $errors['thumb'] = true; unlink("/uploads/$username/images/banner/$filename"); //cleanup: delete source file } } } } // Record in database if (empty($errors)) { // Find existing record and delete existing images $sql = "SELECT `bannerORIGINAL`, `bannerTHUMB` FROM `agent_settings` WHERE (`agent_id`={$user_id}) LIMIT 1"; $result = mysql_query($sql); if (!$result) { unlink("/uploads/$username/images/banner/$filename"); //cleanup: delete source file unlink("/uploads/$username/images/banner/thumbs/$filename"); //cleanup: delete thumbnail file die("<div><b>Error: Problem occurred with Database Query!</b><br /><br /><b>File:</b> " . __FILE__ . "<br /><b>Line:</b> " . __LINE__ . "<br /><b>MySQL Error Num:</b> " . mysql_errno() . "<br /><b>MySQL Error:</b> " . mysql_error() . "</div>"); } $numResults = mysql_num_rows($result); if ($numResults == 1) { $row = mysql_fetch_assoc($result); // Delete old files unlink("/uploads/$username/images/banner/" . $row['bannerORIGINAL']); //delete OLD source file unlink("/uploads/$username/images/banner/thumbs/" . $row['bannerTHUMB']); //delete OLD thumbnail file } // Update/create record with new images if ($numResults == 1) { $sql = "INSERT INTO `agent_settings` (`agent_id`, `bannerORIGINAL`, `bannerTHUMB`) VALUES ({$user_id}, '/uploads/$username/images/banner/$filename', '/uploads/$username/images/banner/thumbs/$filename')"; } else { $sql = "UPDATE `agent_settings` SET `bannerORIGINAL`='/uploads/$username/images/banner/$filename', `bannerTHUMB`='/uploads/$username/images/banner/thumbs/$filename' WHERE (`agent_id`={$user_id})"; } $result = mysql_query($sql); if (!$result) { unlink("/uploads/$username/images/banner/$filename"); //cleanup: delete source file unlink("/uploads/$username/images/banner/thumbs/$filename"); //cleanup: delete thumbnail file die("<div><b>Error: Problem occurred with Database Query!</b><br /><br /><b>File:</b> " . __FILE__ . "<br /><b>Line:</b> " . __LINE__ . "<br /><b>MySQL Error Num:</b> " . mysql_errno() . "<br /><b>MySQL Error:</b> " . mysql_error() . "</div>"); } } // Print success message and how the thumbnail image created if (empty($errors)) { echo "<p>Thumbnail created Successfully!</p>\n"; echo "<img src=\"/uploads/$username/images/banner/thumbs/$filename\" alt=\"New image thumbnail\" />\n"; echo "<br />\n"; } } if (isset($errors['move_source'])) { echo "\t\t<div>Error: Failure occurred moving uploaded source image!</div>\n"; } if (isset($errors['thumb'])) { echo "\t\t<div>Error: Failure occurred creating thumbnail!</div>\n"; } ?> <form action="" enctype="multipart/form-data" method="post"> <input type="hidden" name="MAX_FILE_SIZE" value="<?php echo MAX_SIZE_IN_BYTES; ?>" /> <label for="<?php echo IMG_FIELD_NAME; ?>">Image:</label> <input type="file" name="<?php echo IMG_FIELD_NAME; ?>" id="<?php echo IMG_FIELD_NAME; ?>" /> <?php if (isset($errors['img_empty'])) { echo "\t\t<div class=\"validationerrorText\">Required!</div>\n"; } if (isset($errors['img_type'])) { echo "\t\t<div class=\"validationerrorText\">File type not allowed! GIF/JPEG/PNG only!</div>\n"; } if (isset($errors['img_size'])) { echo "\t\t<div class=\"validationerrorText\">File size too large! Maximum size should be " . MAX_SIZE_IN_BYTES . "bytes!</div>\n"; } if (isset($errors['img_error'])) { echo "\t\t<div class=\"validationerrorText\">File upload error occured! Error code: {$_FILES[IMG_FIELD_NAME]['error']}</div>\n"; } if (isset($errors['img_nametoolong'])) { echo "\t\t<div class=\"validationerrorText\">Filename too long! 200 Chars max!</div>\n"; } if (isset($errors['img_fileexists'])) { echo "\t\t<div class=\"validationerrorText\">An image file already exists with that name!</div>\n"; } ?> <br /><input type="submit" name="submit" id="image1" value="Upload image" /> </form> </body> </html> <?php ################################# # # F U N C T I O N S # ################################# /* * Function: make_thumb * * Creates the thumbnail image from the uploaded image * the resize will be done considering the width and * height defined, but without deforming the image * * @param $sourceFile Path anf filename of source image * @param $destFile Path and filename to save thumbnail as * @param $new_w the new width to use * @param $new_h the new height to use */ function make_thumb($sourceFile, $destFile, $new_w=false, $new_h=false) { if ($new_w === false) { $new_w = THUMB_WIDTH; } if ($new_h === false) { $new_h = THUMB_HEIGHT; } // Get image extension $ext = strtolower(getExtension($sourceFile)); // Copy source switch($ext) { case 'jpg': case 'jpeg': $src_img = imagecreatefromjpeg($sourceFile); break; case 'png': $src_img = imagecreatefrompng($sourceFile); break; case 'gif': $src_img = imagecreatefromgif($sourceFile); break; default: return false; } if (!$src_img) { return false; } // Get dimmensions of the source image $old_x = imageSX($src_img); $old_y = imageSY($src_img); // Calculate the new dimmensions for the thumbnail image // 1. calculate the ratio by dividing the old dimmensions with the new ones // 2. if the ratio for the width is higher, the width will remain the one define in WIDTH variable // and the height will be calculated so the image ratio will not change // 3. otherwise we will use the height ratio for the image // as a result, only one of the dimmensions will be from the fixed ones $ratio1 = $old_x / $new_w; $ratio2 = $old_y / $new_h; if ($ratio1 > $ratio2) { $thumb_w = $new_w; $thumb_h = $old_y / $ratio1; } else { $thumb_h = $new_h; $thumb_w = $old_x / $ratio2; } // Create a new image with the new dimmensions $dst_img = ImageCreateTrueColor($thumb_w, $thumb_h); // Resize the big image to the new created one imagecopyresampled($dst_img, $src_img, 0, 0, 0, 0, $thumb_w, $thumb_h, $old_x, $old_y); // Output the created image to the file. Now we will have the thumbnail into the file named by $filename switch($ext) { case 'jpg': case 'jpeg': $result = imagepng($dst_img, $destFile); break; case 'png': $result = imagegif($dst_img, $destFile); break; case 'gif': $result = imagejpeg($dst_img, $destFile); break; default: //should never occur! } if (!$result) { return false; } // Destroy source and destination images imagedestroy($dst_img); imagedestroy($src_img); return true; } /* * Function: getExtension * * Returns the file extension from a given filename/path * * @param $str the filename to get the extension from */ function getExtension($str) { return pathinfo($str, PATHINFO_EXTENSION); } ?>

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  • Input checkbox name converts period signs into underlines on post

    - by Rakoon
    Hello I am working on an image gallery at the moment. When a user is logged in, an x appears over each image and a checkbox next to it to enable the user to delete that image. Only if the checkbox is checked will the image be deleted. They are both in a (one for each image in the gallery), the small image "x.gif" is an input type="image" that submits the $_POST form. The checkbox inherits the name of the image and is to prevent accidentally pressing the x button and deleting an image. The problem is that the checkbox name, upon posting it gets converted from (for instance) "Image.jpg" to "Image_jpg" When i test it with print_r($_POST); Should I create code for replacing _jpg or _gif into .jpg and .gif after the post or is there a way to make it possible to use period signs in input names? Any help is greatly appreciated.

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  • Which one of the Google Analytics stats should be my top priority to improve SEO: visits, pageviews, bounce rate, new visitors, or visit duration

    - by HOY
    My site is getting a lot of traffic from an image (a company logo image) because this image is ranked 1st in Google search results for a company's title. (I have no idea how that happened.) This image is must for my website, but it is not relevant to the site content, so irrelevant people search for the image and find out about my site. I get interesting statistics: Pros: Total Visits & Avg. New Visits Cons: Avg. Page/Visit, Avg. Visit Duration, Bounce Rate I am confused if this image is helpful to my website. I don't know what the balance between those 5 statistics should be. My website is 2 months old, and we are working on SEO at the moment. Edit: here are the details about the image: Search Keyword: arcelik logo Search Site: google.com.tr Search URL

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  • Architectural advice - web camera remote access

    - by Alan Hollis
    I'm looking for architectural advice. I have a client who I've built a website for which essentially allows users to view their web cameras remotely. The current flow of data is as follows: User opens page to view web camera image. Javascript script polls url on server ( appended with unique timestamp ) every 1000ms Ftp connection is enabled for the cameras ftp user. Web camera opens ftp connection to server. Web camera begins taking photos. Web camera sends photo to ftp server. On image url request: Server reads latest image on hard drive uploaded via ftp for camera. Server deleted any older images from the server. This is working okay at the moment for a small amount of users/cameras ( about 10 users and around the same amount of cameras), but we're starting to worrying about the scalability of this approach. My original plan was instead of having the files read from the server, the web server would open up an ftp connection to the web server and read the latest images directly from there meaning we should have been able to scale horizontally fairly easily. But ftp connection establishment times were too slow ( mainly due to the fact that PHP out of the ox is unable to persist ftp connections ) and so we abandoned this approach and went straight for reading from the hard drive. The firmware provider for the cameras state they're able to build a http client which instead of using ftp to upload the image could post the image to a web server. This seems plausible enough to me, but I'm looking for some architectural advice. My current thought is a simple Nginx/PHP/Redis stack. Web camera issues post requests of latest image to Nginx/PHP and the latest image for that camera is stored in Redis. The clients can then pull the latest image from Redis which should be extremely quick as the images will always be stored in memory. The data flow would then become: User opens page to view web camera image. Javascript script polls url on server ( appended with unique timestamp ) every 1000ms Camera is sent an http request to start posting images to a provided url Web camera begins taking photos. Web camera sends post requests to server as fast as it can On image url request: Server reads latest image from redis Server tells redis to delete later image My questions are: Are there any greater overheads of transferring images via HTTP instead of FTP? Is there a simple way to calculate how many potential cameras we could have streaming at once? Is there any way to prevent potentially DOS'ing our own servers due to web camera requests? Is Redis a good solution to this problem? Should I abandon PHP/Ngix combination and go for something else? Is this proposed solution actually any good? Will adding HTTPs to the mix cause posting the image to become too slow? Thanks in advance Alan

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  • 10 Essential Tools for building ASP.NET Websites

    - by Stephen Walther
    I recently put together a simple public website created with ASP.NET for my company at Superexpert.com. I was surprised by the number of free tools that I ended up using to put together the website. Therefore, I thought it would be interesting to create a list of essential tools for building ASP.NET websites. These tools work equally well with both ASP.NET Web Forms and ASP.NET MVC. Performance Tools After reading Steve Souders two (very excellent) books on front-end website performance High Performance Web Sites and Even Faster Web Sites, I have been super sensitive to front-end website performance. According to Souders’ Performance Golden Rule: “Optimize front-end performance first, that's where 80% or more of the end-user response time is spent” You can use the tools below to reduce the size of the images, JavaScript files, and CSS files used by an ASP.NET application. 1. Sprite and Image Optimization Framework CSS sprites were first described in an article written for A List Apart entitled CSS sprites: Image Slicing’s Kiss of Death. When you use sprites, you combine multiple images used by a website into a single image. Next, you use CSS trickery to display particular sub-images from the combined image in a webpage. The primary advantage of sprites is that they reduce the number of requests required to display a webpage. Requesting a single large image is faster than requesting multiple small images. In general, the more resources – images, JavaScript files, CSS files – that must be moved across the wire, the slower your website. However, most people avoid using sprites because they require a lot of work. You need to combine all of the images and write just the right CSS rules to display the sub-images. The Microsoft Sprite and Image Optimization Framework enables you to avoid all of this work. The framework combines the images for you automatically. Furthermore, the framework includes an ASP.NET Web Forms control and an ASP.NET MVC helper that makes it easy to display the sub-images. You can download the Sprite and Image Optimization Framework from CodePlex at http://aspnet.codeplex.com/releases/view/50869. The Sprite and Image Optimization Framework was written by Morgan McClean who worked in the office next to mine at Microsoft. Morgan was a scary smart Intern from Canada and we discussed the Framework while he was building it (I was really excited to learn that he was working on it). Morgan added some great advanced features to this framework. For example, the Sprite and Image Optimization Framework supports something called image inlining. When you use image inlining, the actual image is stored in the CSS file. Here’s an example of what image inlining looks like: .Home_StephenWalther_small-jpg { width:75px; height:100px; background: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAEsAAABkCAIAAABB1lpeAAAAB GdBTUEAALGOfPtRkwAAACBjSFJNAACHDwAAjA8AAP1SAACBQAAAfXkAAOmLAAA85QAAGcxzPIV3AAAKL s+zNfREAAAAASUVORK5CYII=) no-repeat 0% 0%; } The actual image (in this case a picture of me that is displayed on the home page of the Superexpert.com website) is stored in the CSS file. If you visit the Superexpert.com website then very few separate images are downloaded. For example, all of the images with a red border in the screenshot below take advantage of CSS sprites: Unfortunately, there are some significant Gotchas that you need to be aware of when using the Sprite and Image Optimization Framework. There are workarounds for these Gotchas. I plan to write about these Gotchas and workarounds in a future blog entry. 2. Microsoft Ajax Minifier Whenever possible you should combine, minify, compress, and cache with a far future header all of your JavaScript and CSS files. The Microsoft Ajax Minifier makes it easy to minify JavaScript and CSS files. Don’t confuse minification and compression. You need to do both. According to Souders, you can reduce the size of a JavaScript file by an additional 20% (on average) by minifying a JavaScript file after you compress the file. When you minify a JavaScript or CSS file, you use various tricks to reduce the size of the file before you compress the file. For example, you can minify a JavaScript file by replacing long JavaScript variables names with short variables names and removing unnecessary white space and comments. You can minify a CSS file by doing such things as replacing long color names such as #ffffff with shorter equivalents such as #fff. The Microsoft Ajax Minifier was created by Microsoft employee Ron Logan. Internally, this tool was being used by several large Microsoft websites. We also used the tool heavily on the ASP.NET team. I convinced Ron to publish the tool on CodePlex so that everyone in the world could take advantage of it. You can download the tool from the ASP.NET Ajax website and read documentation for the tool here. I created the installer for the Microsoft Ajax Minifier. When creating the installer, I also created a Visual Studio build task to make it easy to minify all of your JavaScript and CSS files whenever you do a build within Visual Studio automatically. Read the Ajax Minifier Quick Start to learn how to configure the build task. 3. ySlow The ySlow tool is a free add-on for Firefox created by Yahoo that enables you to test the front-end of your website. For example, here are the current test results for the Superexpert.com website: The Superexpert.com website has an overall score of B (not perfect but not bad). The ySlow tool is not perfect. For example, the Superexpert.com website received a failing grade of F for not using a Content Delivery Network even though the website using the Microsoft Ajax Content Delivery Network for JavaScript files such as jQuery. Uptime After publishing a website live to the world, you want to ensure that the website does not encounter any issues and that it stays live. I use the following tools to monitor the Superexpert.com website now that it is live. 4. ELMAH ELMAH stands for Error Logging Modules and Handlers for ASP.NET. ELMAH enables you to record any errors that happen at your website so you can review them in the future. You can download ELMAH for free from the ELMAH project website. ELMAH works great with both ASP.NET Web Forms and ASP.NET MVC. You can configure ELMAH to store errors in a number of different stores including XML files, the Event Log, an Access database, a SQL database, an Oracle database, or in computer RAM. You also can configure ELMAH to email error messages to you when they happen. By default, you can access ELMAH by requesting the elmah.axd page from a website with ELMAH installed. Here’s what the elmah page looks like from the Superexpert.com website (this page is password-protected because secret information can be revealed in an error message): If you click on a particular error message, you can view the original Yellow Screen ASP.NET error message (even when the error message was never displayed to the actual user). I installed ELMAH by taking advantage of the new package manager for ASP.NET named NuGet (originally named NuPack). You can read the details about NuGet in the following blog entry by Scott Guthrie. You can download NuGet from CodePlex. 5. Pingdom I use Pingdom to verify that the Superexpert.com website is always up. You can sign up for Pingdom by visiting Pingdom.com. You can use Pingdom to monitor a single website for free. At the Pingdom website, you configure the frequency that your website gets pinged. I verify that the Superexpert.com website is up every 5 minutes. I have the Pingdom service verify that it can retrieve the string “Contact Us” from the website homepage. If your website goes down, you can configure Pingdom so that it sends an email, Twitter, SMS, or iPhone alert. I use the Pingdom iPhone app which looks like this: 6. Host Tracker If your website does go down then you need some way of determining whether it is a problem with your local network or if your website is down for everyone. I use a website named Host-Tracker.com to check how badly a website is down. Here’s what the Host-Tracker website displays for the Superexpert.com website when the website can be successfully pinged from everywhere in the world: Notice that Host-Tracker pinged the Superexpert.com website from 68 locations including Roubaix, France and Scranton, PA. Debugging I mean debugging in the broadest possible sense. I use the following tools when building a website to verify that I have not made a mistake. 7. HTML Spell Checker Why doesn’t Visual Studio have a built-in spell checker? Don’t know – I’ve always found this mysterious. Fortunately, however, a former member of the ASP.NET team wrote a free spell checker that you can use with your ASP.NET pages. I find a spell checker indispensible. It is easy to delude yourself that you are capable of perfect spelling. I’m always super embarrassed when I actually run the spell checking tool and discover all of my spelling mistakes. The fastest way to add the HTML Spell Checker extension to Visual Studio is to select the menu option Tools, Extension Manager within Visual Studio. Click on Online Gallery and search for HTML Spell Checker: 8. IIS SEO Toolkit If people cannot find your website through Google then you should not even bother to create it. Microsoft has a great extension for IIS named the IIS Search Engine Optimization Toolkit that you can use to identify issue with your website that would hurt its page rank. You also can use this tool to quickly create a sitemap for your website that you can submit to Google or Bing. You can even generate the sitemap for an ASP.NET MVC website. Here’s what the report overview for the Superexpert.com website looks like: Notice that the Sueprexpert.com website had plenty of violations. For example, there are 65 cases in which a page has a broken hyperlink. You can drill into these violations to identity the exact page and location where these violations occur. 9. LinqPad If your ASP.NET website accesses a database then you should be using LINQ to Entities with the Entity Framework. Using LINQ involves some magic. LINQ queries written in C# get converted into SQL queries for you. If you are not careful about how you write your LINQ queries, you could unintentionally build a really badly performing website. LinqPad is a free tool that enables you to experiment with your LINQ queries. It even works with Microsoft SQL CE 4 and Azure. You can use LinqPad to execute a LINQ to Entities query and see the results. You also can use it to see the resulting SQL that gets executed against the database: 10. .NET Reflector I use .NET Reflector daily. The .NET Reflector tool enables you to take any assembly and disassemble the assembly into C# or VB.NET code. You can use .NET Reflector to see the “Source Code” of an assembly even when you do not have the actual source code. You can download a free version of .NET Reflector from the Redgate website. I use .NET Reflector primarily to help me understand what code is doing internally. For example, I used .NET Reflector with the Sprite and Image Optimization Framework to better understand how the MVC Image helper works. Here’s part of the disassembled code from the Image helper class: Summary In this blog entry, I’ve discussed several of the tools that I used to create the Superexpert.com website. These are tools that I use to improve the performance, improve the SEO, verify the uptime, or debug the Superexpert.com website. All of the tools discussed in this blog entry are free. Furthermore, all of these tools work with both ASP.NET Web Forms and ASP.NET MVC. Let me know if there are any tools that you use daily when building ASP.NET websites.

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  • RGB? CMYK? Alpha? What Are Image Channels and What Do They Mean?

    - by Eric Z Goodnight
    They’re there, lurking in your image files. But have you ever wondered what are image channels are? And what do they have to do with RGB and CMYK? Here’s the answer. The channels panel in Photoshop is one of the most disused and misunderstood parts of the program. But images have color channels with or without Photoshop. Read on to find out what color channels are, what RGB and CMYK are, and learn a little bit more about how image files work Latest Features How-To Geek ETC How to Recover that Photo, Picture or File You Deleted Accidentally How To Colorize Black and White Vintage Photographs in Photoshop How To Get SSH Command-Line Access to Windows 7 Using Cygwin The How-To Geek Video Guide to Using Windows 7 Speech Recognition How To Create Your Own Custom ASCII Art from Any Image How To Process Camera Raw Without Paying for Adobe Photoshop What is the Internet? From the Today Show January 1994 [Historical Video] Take Screenshots and Edit Them in Chrome and Iron Using Aviary Screen Capture Run Android 3.0 on a Hacked Nook Google Art Project Takes You Inside World Famous Museums Emerald Waves and Moody Skies Wallpaper Change Your MAC Address to Avoid Free Internet Restrictions

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  • How to detect image dimensions and run commands on them?

    - by Jon
    I have a directory full of images, some of which are portrait-sized instead of landscape-sized, and I want to open the portrait-sized ones with an image editor. I can run the imagemagick command identify and I get an output like something.jpg JPEG 1920x1255 1920x1255+0+0 8-bit DirectClass 159KB 0.000u 0:00.000. How can I have a script interpret this output, i.e. decide which is bigger, the 1920 or the 1255, and then run a command on it if it is?

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  • There is Hardly a Scratch on It! [Humorous Image]

    - by Asian Angel
    That hard drive has lots of life left in it… View the Entire Set of Photos of this Hard Drive (29 Image Set) I finally removed this failed SCSI drive 2 years after the server reported it had failed. Yeah that report seems about right. [via Fail Desk] HTG Explains: How Windows 8′s Secure Boot Feature Works & What It Means for Linux Hack Your Kindle for Easy Font Customization HTG Explains: What Is RSS and How Can I Benefit From Using It?

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  • How to move packages from the live image to a pool on the disc?

    - by int_ua
    Currently I'm using UCK and trying to make Edubuntu 12.04.1 DVD launch installer on 256Mb RAM: How to install Edubuntu on a system with low memory (256 Mb)? I was reading release notes for 12.10 and noticed that Language packs have now been moved off from the live image to a pool on the disc. How can I move other packages correctly so they would be available to the live system and for installation without network access?

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  • Should I set NOINDEX header for my JS, CSS and image files?

    - by Yoga
    Are there any harms if my site send NOINDEX headers for all my static assets? For image files, I refer to those valueless, e.g. background images, button images, etc. Update: more background information I have this concern is since recent Google said they also execute JS and they might fetch content via Ajax. So, for example, if I send noindex for my jQuery script, so Google would not be able to use them to load Ajax, I suppose it is not good for my site's SEO, right?

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  • Can i place a image as a map and then code a grid over the top of it?

    - by kraze
    what i'm trying to do is make a huge map, best way i found is just make a big map and save it as a image... can i code a grid over the top so i can implement tile based movement for my character? afterwards place collision tiles so they can't move to certain spots. btw this is in visual studio 2010 using XNA Anyone able to explain the process of how i would do this and if its even viable? thanks for your help

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  • Why when I log in my two screens shows the same image automatically?

    - by forellana
    When I log in on my computer, first my two monitors shows their own part of a larger desktop, then automatically changes to the same image on both screens, but I don't want to happen this, Is there any configuration to avoid this? About my hardware: 00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 09) 00:02.1 Display controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 09)

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  • How does it hurt to use Linux (Ubuntu) as a guest OS for all my tasks?

    - by sauparna
    I have a machine running Windows, where the disk has two partitions C (50 GB) and D (250GB). I do research in Information Retrieval and need to work with a large corpus (more than 50 GB) and in Linux. So if I want to install Linux on the existing system, keeping the Windows installation intact, will it be fine to run it in a virtual box? (say, QEMU, VMWare, etc.) An alternative is using Wubi. In that case the Linux installation has to be on drive C. Then, if I keep a small Linux installation (say 5GB) on C, and my corpus on D (mounted in Linux), how will it affect the performance of my programs which would be accessing the mounted Windows drive D. Is it feasible to use Linux this way? Which of the above is better if at all they are a way out? Note : Since my post in July 2010, I have been using and have tried several ways of maintaining a disk-image that I can mount in Linux. I had a 100GB qcow2 disk and a 100GB raw disk, both formatted to an EXT3 file system. I was mounting and connecting to the qcow2 disk using qemu-nbd. The problem was that every now and then, the connection to the disk would get lost and the running programs would throw disk I/O errors. The raw disk would mount and work fine as a loop mounted device, but when writing data to it, the mount.ntfs program would hog the CPU and the process would take an enormous amount of time. I was in fact running make on a piece of software located on this raw disk, and after a point of time make was waiting while mount.ntfs would show 100% CPU usage.

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  • what's the difference between a Volume and a Partition in Windows 7 diskpart

    - by user170232
    I was trying to follow the Intel guide for setting up iRST (Intel Rapid Start Technology) on my new laptop. The Intel manual says you need to create a *Volume that is as big or bigger than your available memory, set it to a specific id (id=84), then go into the iRST tool and adjust some settings. Looking at the disk manager on the laptop, I see there is already a Partition labeled as "Hibernation Partition" which is a little bigger than the memory in my system. So it looks like iRST was already set up...BUT, it's a Partition, not a Volume. Here's what the manual says to do: (from: http://download.intel.com/support/motherboards/desktop/sb/rapid_start_technology_user_guide.pdf) diskpart list disk select disk x (where x is the disk to use, there's only one disk in this laptop) create partition primary size=X000 (where X000 is the size to create) detail disk (which lists details for the disk. This is where i get hung up) select volume Z (where Z is the *partition you created previously) ** it says the 'detail disk' command will list the volume #, but it doesn't. ** 'detail disk' only lists two "volumes" for Recovery and OS. ** if i do 'list partition', i see the 8 GB *partition labeled as "Hibernation Partition") ** so I can't continue with the following steps: set id=84 override exit The reason I went looking for the manual is because when iRST is enabled in the BIOS, the system won't resume from sleep. When it's disabled, it works fine, but the system goes into (legacy?) Hibernation mode and takes a while to come out of Hibernation. the iRST is supposed to resume from deep sleep very quickly. So, what's the difference between a Volume and a Partition? Should I delete the Hibernation Partition and create a Hibernation Volume? Anyone have any ideas? (if it matters, this is on a Dell XPS 13 with BIOS A08) Thanks! J

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  • The fastest way to encode image+audio for Youtube from command line?

    - by Pavel Vlasov
    I have an mp3 and image and I want to make a simple clip to upload onto Youtube. Is there a fast solution? If video formats are so bad designed, then maybe it is possible to use a prerendered video-only clip? This works good except it takes as much time as the audio lasts: ffmpeg -loop_input -r ntsc -i "%IMAGE%" -i "%AUDIO%" -r 1 -acodec copy -shortest -re -force_fps "%VIDEO%" This takes a second but results in a black screen video that is successfully played by a desktop video player but not acceptable by Youtube: ffmpeg -i "%IMAGE%" -i "%AUDIO%" -acodec copy "%VIDEO%" Windows 7. Preserving audio quality is preferred over video quality.

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  • OS X Hard drive recovery

    - by Adam
    I am trying to recover data from a bad Seagate 1TB hard drive in a 2010 iMac. One day the iMac wouldn't boot (stuck at gray screen on startup). I removed the hard drive from the iMac and connected it to a MacBook using a 3.5" HDD to USB adapter. The hard drive wouldn't mount but it did display in Disk Utility that that there were 2 partitions on the disk. I tried to run Disk Warrior and it showed thousands of errors but still wouldn't mount. At this time the hard drive only show one partition in Disk Utility. Next I tried putting the hard drive in a desktop PC and running Spin Rite - which then gave me several division overflow errors (even with running Spin Rite with a newer version of DOS). The SMART status on the drive reports that the drive has had failures and HD Tune referenced the drive had once hit 59 degrees celsius. Disk Utility gives me the following message when running a pair: Error: Disk Utility can’t repair this disk. Back up as many of your files as possible, reformat the disk, and restore your backed-up files. Overall, the hard drive spins up and sounds OK - there are no clicking noises but the hard drive won't mount and displays as a light gray "Macintosh HD" in disk utility. Any tips or advice on how to recover data on this drive would be GREATLY appreciated! Are there any other tools I can try before calling it quits on this drive? Thank you

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  • How to create custom Live CD with upgraded linux-image kernel?

    - by ???
    I'm following this tutorial to customize a Live CD, http://www.debuntu.org/how-to-customize-your-ubuntu-live-cd However, it's failed to upgrade linux-image, I guess it's just can't update-grub. Any idea? EDIT I copied the custom/ directory into an ext4 image, now the linux-image-2.6.35-24 package is successfully upgrade. But as shown in the original CDROM, the vmlinuz-* and initrd.img-* file is moved out to /casper/vmlinuz and casper/initrd.lz. Well, I can move vmlinuz-2.6.34-24-generic to /casper/vmlinuz, but how to compress file initrd.img-2.6.35-24-generic in .lz format? (It looks like lzip, but it's not: ) # cd original-maverick/casper # lzip -d initrd.lz initrd.lz: bad magic number (file not in lzip format).

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  • Hard drive not correctly recognized on a new Windows 7 installation, but works correctly on Windows XP

    - by david
    I'm having problems configuring a hard disk in a brand new, clean Windows 7 installation. System specs: Hard disk: WD VelociRaptor WD6000HLHX (600 GB, 10000 RPM) Motherboard: Gigabyte Z77X-UD3H BIOS SATA mode set to AHCI (not RAID), with disk connected to SATA0 (6 Gb/s port). Windows 7 Enterprise SP1 64-bit The disk is recognized by the BIOS and is correctly identified, with the name and size correctly reported. Windows recognizes the disk itself and reports the device is functioning correctly, but it doesn't appear in Explorer. Disk Management shows the drive, but incorrectly states that it is uninitialized and has no partitions. If I try to initialize the drive, I get an error saying that "the system cannot find the file specified" (what file?). Before connecting the drive to the new machine, I partitioned and formatted it under Windows XP SP2, creating 2 partitions (MBR, not GPT) and copying over a boatload of data. However, none of this data appears under Windows 7. If I put the disk back into the Windows XP machine, I can access the disk and all of its data. Is it possible to get Windows 7 to correctly recognize the disk without having to erase it and start over? If so, how do I do so? I checked this question, which seems to cover the same issue, but it didn't help.

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  • Does anyone have experience with BSODs while creating a universal image with FOG?

    - by Devator
    I want to create a Windows XP universal image to image our computers using FOG server. The FOG server part is running fine, however when creating a Windows XP universal image, it keeps crashing (BSOD) with the 0x000007b error. I believe this has todo with the Mass Storage drivers, I followed many tutorials, but each of them crashes with the 0x000007b error. FYI, I followed this tutorial (but couldn't download the files, the host is down). I was wondering if any of you had experience with this and knows how to solve my problem?

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