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  • Scalability 101: How can I design a scalable web application using PHP?

    - by Legend
    I am building a web-application and have a couple of quick questions. From what I learnt, one should not worry about scalability when initially building the app and should only start worrying when the traffic increases. However, this being my first web-application, I am not quite sure if I should take an approach where I design things in an ad-hoc manner and later "fix" them. I have been reading stories about how people start off with an app that gets millions of users in a week or two. Not that I will face the same situation but I can't help but wonder, how do these people do it? Currently, I bought a shared hosting account on Lunarpages and that got me started in building and testing the application. However, I am interested in learning how to build the same application in a scalable-manner using the cloud, for instance, Amazon's EC2. From my understanding, I can see a couple of components: There is a load balancer that first receives requests and then decides where to route each request This request is then handled by a server replica that then processes the request and updates (if required) the database and sends back the response to the client If a similar request comes in, then a caching mechanism like memcached kicks into picture and returns objects from the cache A blackbox that handles database replication Specifically, I am trying to do the following: Setting up a load balancer (my homework revealed that HAProxy is one such load balancer) Setting up replication so that databases can be synchronized Using memcached Configuring Apache to work with multiple web servers Partitioning application to use Amazon EC2 and Amazon S3 (my application is something that will need great deal of storage) Finally, how can I avoid burning myself when using Amazon services? Because this is just a learning phase, I can probably do with 2-3 servers with a simple load balancer and replication but until I want to avoid paying loads of money accidentally. I am able to find resources on individual topics but am unable to find something that starts off from the big picture. Can someone please help me get started?

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  • PHP Access property of a class from within a class instantiated in the original class.

    - by Iain
    I'm not certain how to explain this with the correct terms so maybe an example is the best method... $master = new MasterClass(); $master->doStuff(); class MasterClass { var $a; var $b; var $c; var $eventProccer; function MasterClass() { $this->a = 1; $this->eventProccer = new EventProcess(); } function printCurrent() { echo '<br>'.$this->a.'<br>'; } function doStuff() { $this->printCurrent(); $this->eventProccer->DoSomething(); $this->printCurrent(); } } class EventProcess { function EventProcess() {} function DoSomething() { // trying to access and change the parent class' a,b,c properties } } My problem is i'm not certain how to access the properties of the MasterClass from within the EventProcess-DoSomething() method? I would need to access, perform operations on and update the properties. The a,b,c properties will be quite large arrays and the DoSomething() method would be called many times during the execuction of the script. Any help or pointers would be much appreciated :)

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  • How can I overlay a watermark on an already resampled image in PHP (using GD) ?

    - by Rick
    Here's my current code: define('IMG_WIDTH', (isset ($_GET['width'])) ? (int) $_GET['width'] : 99); define('IMG_HEIGHT', (isset ($_GET['height'])) ? (int) $_GET['height'] : 75); $image = imagecreatefromjpeg($_GET['image']); $origWidth = imagesx($image); $origHeight = imagesy($image); $croppedThumb = imagecreatetruecolor(IMG_WIDTH, IMG_HEIGHT); if ($origWidth > $origHeight) { $leftOffset = ($origWidth - $origHeight) / 2; imagecopyresampled($croppedThumb, $image, 0, 0, $leftOffset, 0, IMG_WIDTH, IMG_HEIGHT, $origHeight, $origHeight); } else { $topOffset = ($origHeight - $origWidth) / 2; imagecopyresampled($croppedThumb, $image, 0, 0, 0, $topOffset, IMG_WIDTH, IMG_HEIGHT, $origWidth, $origWidth); } It basically takes an image and re-sizes it to create a thumbnail. It works quite nicely. What I would like to do now is add a watermark to the bottom right corner. I've seen the imagecopymerge function used for this... However, that doesn't seem to allow me to supply a resampled image as the source. How can I take my already modified image and add a watermark? :/ I've thought of saving the image to /tmp and then unlink()'ing it once I've added the watermark but that seems like a bit of a mess...

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  • How can I get columns name from select query in php?

    - by Farshad Mehrvarzan
    I want to execute a SELECT query but I don't how many columns to select. Like: select name, family from persons; How can I know which columns to select? "I am currently designing a site for the execute query by users. So when the user executes this query, I won't know which columns selected. But when I want to show the results and draw a table for the user I should know which columns selected."

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  • How can I use multiple PHP header content types on the same page? is this possible?

    - by Jon
    Is it possible to use multiple header types in one document? For example: header("Content-type: image/jpeg"); header('Content-Type: text/html; charset=utf-8'); returns the whole page as text/html... while header('Content-Type: text/html; charset=utf-8'); header("Content-type: image/jpeg"); Returns the whole page as an image.... How can I use both types of content on the same page? I'm using ob_start() at the top and ob_end_flush() at the beginning.

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  • How do I keep a count of undefined strings within a loop using PHP?

    - by mike
    I'm using a loop within a loop to try to generate keyword combinations and also find the ones that have been used the most. My outside loop just queries a list of keywords (lets use "chicago" as our first keyword, 3 records were found). The inside loop finds all the records in the "posts" table where keyword = "chicago". Within this loop, I need to generate strings based on info I found in the database. Which, would look something like "chicago bulls", "chicago bears", "chicago cubs" etc... I know how to do everything up until this point, but how do I temporary hold these generated strings and count how many times they have been found within the 3 records?

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  • How to read expected child nodes of a given node from schema in PHP?

    - by MartyIX
    I was wondering if there's an implementation of a XML schema reader that for an arbitrary node in XML schema provides list of nodes which are supposed to be present as child nodes of given node, restrictions on nodes and so on. I'm planning to program it for my purposes but I would like to know if it isn't solved somewhere. I really need only a small subset what I described above. Thanks for tips!

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  • what property should i set to Fit the text in label

    - by Shadow
    Hi, i want to display a big string in Qlablel for this simply i have created a label in Qt GUI editor, then i put the string, with the Wordwrap property ON. here text is not coming to the next line itself, instead its crossing the view region. but if i give "\n" it works well. how to put up big string in label, to display in visible region.

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  • What's quicker and better to determine if an array key exists in PHP?

    - by alex
    Consider these 2 examples $key = 'jim'; // example 1 if (isset($array[$key])) { doWhatIWant(); } // example 2 if (array_key_exists($key, $array)) { doWhatIWant(); } I'm interested in knowing if either of these are better. I've always used the first, but have seen a lot of people use the second example on this site. So, which is better? Faster? Clearer intent? Update Thanks for the quality answers. I now understand the difference between the 2. A benchmark states that isset() alone is quicker than array_key_exists(). However, if you want the isset() to behave like array_key_exists() it is slower.

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  • How to display content of one site in another using PHP?

    - by Joyan
    Hello I'm trying to show contents of two websites in one another , someone suggest me to use RSS reader but my question is : is there anything else i could try to show the contents , beside using rss !? i thought i can connect to the database of another website , but that didnt work / thanks in advance

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  • How to code an efficient blacklist filter function in php?

    - by achairapart
    So, I have three arrays like this: [items] => Array ( [0] => Array ( [id] => someid [title] => sometitle [author] => someauthor ... ) ... ) and also a string with comma separated words to blacklist: $blacklist = "some,words,to,blacklist"; Now I need to match these words with (as they can be one of) id, title, author and show results accordingly. I was thinking of a function like this: $pattern = '('.strtr($blacklist, ",", "|").')'; // should return (some|words|etc) foreach ($items as $item) { if ( !preg_match($pattern,$item['id']) || !preg_match($pattern,$item['title']) || !preg_match($pattern,$item['author']) ) { // show item } } and I wonder if this is the most efficient way to filter the arrays or I should use something with strpos() or filter_var with FILTER_VALIDATE_REGEXP ... Note that this function is repeated per 3 arrays. However, each array will not contain more than 50 items.

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  • Which is the correct design pattern for my PHP application?

    - by user1487141
    I've been struggling to find good way to implement my system which essentially matches the season and episode number of a show from a string, you can see the current working code here: https://github.com/huddy/tvfilename I'm currently rewriting this library and want a nicer way to implement how the the match happens, currently essentially the way it works is: There's a folder with classes in it (called handlers), every handler is a class that implements an interface to ensure a method called match(); exists, this match method uses the regex stored in a property of that handler class (of which there are many) to try and match a season and episode. The class loads all of these handlers by instantiating each one into a array stored in a property, when I want to try and match some strings the method iterates over these objects calling match(); and the first one that returns true is then returned in a result set with the season and episode it matched. I don't really like this way of doing it, it's kind of hacky to me, and I'm hoping a design pattern can help, my ultimate goal is to do this using best practices and I wondered which one I should use? The other problems that exist are: More than one handler could match a string, so they have to be in an order to prevent the more greedy ones matching first, not sure if this is solvable as some of the regex patterns have to be greedy, but possibly a score system, something that shows a percentage of how likely the match is correct, i'd have no idea how to actually implement this though. I'm not if instantiating all those handlers is a good way of doing it, speed is important, but using best practices and sticking to design patterns to create good, extensible and maintainable code is my ultimate priority. It's worth noting the handler classes sometimes do other things than just regex matching, they sometimes prep the string to be matched by removing common words etc. Cheers for any help Billy

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  • How to separate database entries and display them as individual records using PHP?

    - by Clark
    I used to have database entries separated by ampersands (&), but this was causing certain search issues so I decided to encapsulate my entries on both sides by $ and & symbols like: $this& But I am having trouble displaying all the entries of a cell as individual records. Before I used: $unsplitItems = $row['files']; $files = explode("@", $unsplitItems); foreach ($files as $file) { if(strlen($file)) { echo "<li>$file</li>"; } } Any idea how I can split my records and display all the items in the array as individual entries?

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  • Implementing Tagging System with PHP and mySQL. Caching help!!!

    - by Hamid Sarfraz
    With reference to this post: http://stackoverflow.com/questions/2122546/how-to-implement-tag-counting I have implemented the suggested 3 table tagging system completely. To count the number of Articles per tag, i am using another column named tagArticleCount in the tag definition table. (other columns are tagId, tagText, tagUrl, tagArticleCount). If i implement realtime editing of this table, so that whenever user adds another tag to article or deletes an existing tag, the tag_definition_table is updated to update the counter of the added/removed tag. This will cost an extra query each time any modification is made. (at the same time, related link entry for tag and article is deleted from tagLinkTable). An alternative to this is not allowing any real time editing to the counter, instead use CRONs to update counter of each tag after a specified time period. Here comes the problem that i want to discuss. This can be seen as caching the article count in database. Can you please help me find a way to present the articles in a list when a tag is explored and when the article counter for that tag is not up to date. For example: 1. Counter shows 50 articles, but there are infact 55 entries in the tag link table (that links tags and articles). 2. Counter shows 50 articles, but there are infact 45 extries in the tag link table. How to handle these 2 scenerios given in example. I am going to use APC to keep cache of these counters. Consider it too in your solution. Also discuss performance in the realtime / CRONNED counter updates.

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  • How to remove $ from associate array using Json_decode in php?

    - by Chase
    I am trying to use the youtube API to pulldown some videos for my site. Currently am running this code here: //Youtube Videos Pull Down $youtubeURL = "http://gdata.youtube.com/feeds/api/videos?alt=json&q=cats+cradle+chapel+hill&orderby=published&max-results=10&v=2"; $youtubeSearch = file_get_contents($youtubeURL, true); $youtubeArray = json_decode($youtubeSearch, true); Not having any problems accessing certain elements of the associative array however youtube's api is putting $ in many of its array elements .. such as [media$group] Anytime I try to access an array with one of the $ elements in it, it doesn't work. Suggestions? I have tried preg_replace but can't seem to get my expression right.

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  • What's the fastest way to compare two objects in PHP?

    - by johnnietheblack
    Let's say I have an object - a User object in this case - and I'd like to be able to track changes to with a separate class. The User object should not have to change it's behavior in any way for this to happen. Therefore, my separate class creates a "clean" copy of it, stores it somewhere locally, and then later can compare the User object to the original version to see if anything changed during its lifespan. Is there a function, a pattern, or anything that can quickly compare the two versions of the User object? Option 1 Maybe I could serialize each version, and directly compare, or hash them and compare? Option 2 Maybe I should simply create a ReflectionClass, run through each of the properties of the class and see if the two versions have the same property values? Option 3 Maybe there is a simple native function like objects_are_equal($object1,$object2);? What's the fastest way to do this?

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  • Codeigniter .htaccess not working in subdirectory

    - by xzdead
    I have this codeingniter project structure webRoot | |/application | | | |/controllers | | | |/admin | |/public | | | |/admin | | | | | |/css | | |/img | |/css | |/img And this is my .htacess file, located in /public. I use this in every local project running xampp: <IfModule mod_rewrite.c> RewriteEngine On RewriteBase / RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^(.*)$ index.php/$1 [L] </IfModule> <IfModule !mod_rewrite.c> # If we don't have mod_rewrite installed, all 404's # can be sent to index.php, and everything works as normal. # Submitted by: ElliotHaughin ErrorDocument 404 /index.php </IfModule> It works fine in localhost, but doesn't work in a dreamhost server. I always get "no input file specified". So after searching the web and trying lots of combinations, the best I got is this .htaccess file: Options +FollowSymLinks RewriteEngine On RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^ index.php [L] With this one, if I go to http://development.mydomain.com - I see the codeigniter welcome page But if I go to: http://development.mydomain.com/admin - I see the directory listing of /public/admin and doesn't execute the controller in /application/controllers/admin Again, if I go to: http://development.mydomain.com/admin/admin - I see the private area, it executes the controller and goes to the default controller defined in routes, "dashboard" This works fine too: http://development.mydomain.com/admin/dashboard I have set in my config file: $config['index_page'] = ''; $config['base_url'] = ''; $config['uri_protocol'] = 'AUTO'; I think that whatever is wrong in my .htaccess is causing other path issues I have with my project. Any help would be great. Thanks to all in advance EDIT: I removed this line: RewriteCond %{REQUEST_FILENAME} !-d because admin directory exists, that's why I see the public directory listing. But now I see the codeigniter welcome page when I go to http://development.mydomain.com/admin So now my .htaccess file looks like: Options +FollowSymLinks RewriteEngine On RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^ index.php [L] #RewriteRule ^(.*)$ /index.php?/$1 [L] I also tried with the commented RewriteRule but I get the same result.

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