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• Google Chrome audit on caching

  - by Álvaro G. Vicario

  If I run an audit on my sites with Google Chrome, I get this message in the Leverage browser caching section: The following resources are missing a cache expiration. Resources that do not specify an expiration may not be cached by browsers: A list of all the pictures follows. I get a similar notice in Leverage proxy caching: Consider adding a "Cache-Control: public" header to the following resources: Apart from pictures, I also get a notice about HTML, CSS and JavaScript files: The following resources are explicitly non-cacheable. Consider making them cacheable if possible: Its funny because I've worked hard to cache all static contents (except for pictures, where I just left Apache's default settings). Firefox does indeed store all these items in cache. Is there anything I should improve in my HTTP headers? Here's the complete header set of some items as loaded after removing the browser caché. Pictures use default settings I didn't really check before, the rest should be cachéd for three hours. I can set headers with both .htaccess and PHP. PNG HTTP/1.1 200 OK Date: Sat, 31 Jul 2010 12:46:14 GMT Server: Apache Last-Modified: Thu, 18 Mar 2010 21:40:54 GMT Etag: "c48024-230-4821a15d6c580" Accept-Ranges: bytes Content-Length: 560 Keep-Alive: timeout=4 Connection: Keep-Alive Content-Type: image/png HTML HTTP/1.1 200 OK Date: Sat, 31 Jul 2010 12:46:13 GMT Server: Apache X-Powered-By: PHP/5.2.11 Expires: Sat, 31 Jul 2010 15:46:13 GMT Cache-Control: max-age=10800, s-maxage=10800, must-revalidate, proxy-revalidate Content-Encoding: gzip Vary: Accept-Encoding Last-Modified: Wed, 24 Mar 2010 20:30:36 GMT Keep-Alive: timeout=4 Connection: Keep-Alive Transfer-Encoding: chunked Content-Type: text/html; charset=ISO-8859-15 CSS HTTP/1.1 200 OK Date: Sat, 31 Jul 2010 12:48:21 GMT Server: Apache X-Powered-By: PHP/5.2.11 Expires: Sat, 31 Jul 2010 15:48:21 GMT Cache-Control: max-age=10800, s-maxage=10800, must-revalidate, proxy-revalidate Content-Encoding: gzip Vary: Accept-Encoding Last-Modified: Thu, 18 Mar 2010 21:40:12 GMT Keep-Alive: timeout=4 Connection: Keep-Alive Transfer-Encoding: chunked Content-Type: text/css JavaScript HTTP/1.1 200 OK Date: Sat, 31 Jul 2010 12:48:21 GMT Server: Apache X-Powered-By: PHP/5.2.11 Expires: Sat, 31 Jul 2010 15:48:21 GMT Cache-Control: max-age=10800, s-maxage=10800, must-revalidate, proxy-revalidate Content-Encoding: gzip Vary: Accept-Encoding Last-Modified: Thu, 18 Mar 2010 21:40:12 GMT Keep-Alive: timeout=4 Connection: Keep-Alive Transfer-Encoding: chunked Content-Type: application/x-javascript Update I've tested Jumby's suggestion and set my CSS's expire to 1 year: Cache-Control:max-age=31536000, s-maxage=31536000, must-revalidate, proxy-revalidate Connection:Keep-Alive Content-Encoding:gzip Content-Length:4198 Content-Type:text/css Date:Mon, 02 Aug 2010 20:48:56 GMT Expires:Tue, 02 Aug 2011 20:48:56 GMT Keep-Alive:timeout=5, max=99 Last-Modified:Thu, 18 Mar 2010 20:40:12 GMT Server:Apache/2.2.14 (Win32) PHP/5.3.1 Vary:Accept-Encoding X-Powered-By:PHP/5.3.1 However, Chrome still claims "explicitly non-cacheable".

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• Find location using only distance and range?

  - by pinnacler

  Triangulation works by checking your angle to three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and it's to my right at 90 degrees." Repeat 2 more times for different targets and angles. Trilateration works by checking your distance from three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and I'm 100 meters away from that." Repeat 2 more times for different targets and ranges. But both of those methods rely on knowing WHAT you're looking at. Say you're in a forest and you can't differentiate between trees, but you know where key trees are. These trees have been hand picked as "landmarks." You have a robot moving through that forest slowly. Do you know of any ways to determine location based solely off of angle and range, exploiting geometry between landmarks? Note, you will see other trees as well, so you won't know which trees are key trees. Ignore the fact that a target may be occluded. Our pre-algorithm takes care of that. 1) If this exists, what's it called? I can't find anything. 2) What do you think the odds are of having two identical location 'hits?' I imagine it's fairly rare. 3) If there are two identical location 'hits,' how can I determine my exact location after I move the robot next. (I assume the chances of having 2 occurrences of EXACT angles in a row, after I reposition the robot, would be statistically impossible, barring a forest growing in rows like corn). Would I just calculate the position again and hope for the best? Or would I somehow incorporate my previous position estimate into my next guess? If this exists, I'd like to read about it, and if not, develop it as a side project. I just don't have time to reinvent the wheel right now, nor have the time to implement this from scratch. So if it doesn't exist, I'll have to figure out another way to localize the robot since that's not the aim of this research, if it does, lets hope it's semi-easy.

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• Find location using only distance and bearing?

  - by pinnacler

  Triangulation works by checking your angle to three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and it's to my right at 90 degrees." Repeat 2 more times for different targets and angles. Trilateration works by checking your distance from three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and I'm 100 meters away from that." Repeat 2 more times for different targets and ranges. But both of those methods rely on knowing WHAT you're looking at. Say you're in a forest and you can't differentiate between trees, but you know where key trees are. These trees have been hand picked as "landmarks." You have a robot moving through that forest slowly. Do you know of any ways to determine location based solely off of angle and range, exploiting geometry between landmarks? Note, you will see other trees as well, so you won't know which trees are key trees. Ignore the fact that a target may be occluded. Our pre-algorithm takes care of that. 1) If this exists, what's it called? I can't find anything. 2) What do you think the odds are of having two identical location 'hits?' I imagine it's fairly rare. 3) If there are two identical location 'hits,' how can I determine my exact location after I move the robot next. (I assume the chances of having 2 occurrences of EXACT angles in a row, after I reposition the robot, would be statistically impossible, barring a forest growing in rows like corn). Would I just calculate the position again and hope for the best? Or would I somehow incorporate my previous position estimate into my next guess? If this exists, I'd like to read about it, and if not, develop it as a side project. I just don't have time to reinvent the wheel right now, nor have the time to implement this from scratch. So if it doesn't exist, I'll have to figure out another way to localize the robot since that's not the aim of this research, if it does, lets hope it's semi-easy.

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• Function Point Analysis -- a seriously over-estimating technique?

  - by kizzx2

  I know questions about FPA has been asked numerous times before, but this time I'm taking a more analytical angle at it, backed up with data. 1. First, some data This question is based on a tutorial. He had a "Sample Count" section where he demonstrated it step by step. You can see some screenshots of his sample application here. In the end, he calculated the unadjusted FP to be 99. There is another article on InformIT with industry data on typical hour/FP. It ranges from 2 hours/FP to 27.4 hours/FP. Let's try to stick with 2 for the moment (since SO readers are probably the more efficient crowd :p). 2. Reality check!? Now just check out the screenshots again. Do a little math here 99 * 2 = 198 hours 198 hours / 40 hours per week = 5 weeks Seriously? That sample application is going to take 5 weeks to implement? Is it just my feeling that it wouldn't take any decent programmer longer than one week to have it completed? Now let's try estimating the cost of the project. We'll use New York's minimum wage at the moment (Wikipedia), which is $7.25 198 * 7.25 = $1435.5 From what I could see from the screenshots, this application is a small excel-improvement app. I could have bought MS Office Pro for 200 bucks which gives me greater interoperability (.xls files) and flexibility (spreadsheets). (For the record, that same Web site has another article discussing productivity. It seems like they typically use 4.2 hours/FP, which gives us even more shocking stats: 99 * 4.2 = 415 hours = 10 weeks = almost 3 whopping months! 415 hours * $7.25 = $3000 zomg (That's even assuming that all our poor coders get the minimum wage!) 3. Am I missing something here? Right now, I could come up with several possible explanation: FPA is really only suited for bigger projects (1000+ FPs) so it becomes extremely inaccurate at smaller scale. The hours/FP metric fluctuates abruptly from team to team, project to project. For a small project like this, we could have used something like 0.5 hour/FP or something. (Now this kind of makes the whole estimation thing pointless, unless my firm does the same type of projects for several years with the same team, not really common.) From my experience with several software metrics, Function Point is really not a lightweight metric. If the hour/FP thing fluctuates so much, then what's the point, maybe I could have gone with User Story Points which is a lot faster to get and arguably almost as uncertain. What would be the FP experts' answers to this?

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• PostgreSQL - fetch the row which has the Max value for a column

  - by Joshua Berry

  I'm dealing with a Postgres table (called "lives") that contains records with columns for time_stamp, usr_id, transaction_id, and lives_remaining. I need a query that will give me the most recent lives_remaining total for each usr_id There are multiple users (distinct usr_id's) time_stamp is not a unique identifier: sometimes user events (one by row in the table) will occur with the same time_stamp. trans_id is unique only for very small time ranges: over time it repeats remaining_lives (for a given user) can both increase and decrease over time example: time_stamp|lives_remaining|usr_id|trans_id ----------------------------------------- 07:00 | 1 | 1 | 1 09:00 | 4 | 2 | 2 10:00 | 2 | 3 | 3 10:00 | 1 | 2 | 4 11:00 | 4 | 1 | 5 11:00 | 3 | 1 | 6 13:00 | 3 | 3 | 1 As I will need to access other columns of the row with the latest data for each given usr_id, I need a query that gives a result like this: time_stamp|lives_remaining|usr_id|trans_id ----------------------------------------- 11:00 | 3 | 1 | 6 10:00 | 1 | 2 | 4 13:00 | 3 | 3 | 1 As mentioned, each usr_id can gain or lose lives, and sometimes these timestamped events occur so close together that they have the same timestamp! Therefore this query won't work: SELECT b.time_stamp,b.lives_remaining,b.usr_id,b.trans_id FROM (SELECT usr_id, max(time_stamp) AS max_timestamp FROM lives GROUP BY usr_id ORDER BY usr_id) a JOIN lives b ON a.max_timestamp = b.time_stamp Instead, I need to use both time_stamp (first) and trans_id (second) to identify the correct row. I also then need to pass that information from the subquery to the main query that will provide the data for the other columns of the appropriate rows. This is the hacked up query that I've gotten to work: SELECT b.time_stamp,b.lives_remaining,b.usr_id,b.trans_id FROM (SELECT usr_id, max(time_stamp || '*' || trans_id) AS max_timestamp_transid FROM lives GROUP BY usr_id ORDER BY usr_id) a JOIN lives b ON a.max_timestamp_transid = b.time_stamp || '*' || b.trans_id ORDER BY b.usr_id Okay, so this works, but I don't like it. It requires a query within a query, a self join, and it seems to me that it could be much simpler by grabbing the row that MAX found to have the largest timestamp and trans_id. The table "lives" has tens of millions of rows to parse, so I'd like this query to be as fast and efficient as possible. I'm new to RDBM and Postgres in particular, so I know that I need to make effective use of the proper indexes. I'm a bit lost on how to optimize. I found a similar discussion here. Can I perform some type of Postgres equivalent to an Oracle analytic function? Any advice on accessing related column information used by an aggregate function (like MAX), creating indexes, and creating better queries would be much appreciated! P.S. You can use the following to create my example case: create TABLE lives (time_stamp timestamp, lives_remaining integer, usr_id integer, trans_id integer); insert into lives values ('2000-01-01 07:00', 1, 1, 1); insert into lives values ('2000-01-01 09:00', 4, 2, 2); insert into lives values ('2000-01-01 10:00', 2, 3, 3); insert into lives values ('2000-01-01 10:00', 1, 2, 4); insert into lives values ('2000-01-01 11:00', 4, 1, 5); insert into lives values ('2000-01-01 11:00', 3, 1, 6); insert into lives values ('2000-01-01 13:00', 3, 3, 1);

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• (resolved) empty response body in ajax (or 206 Partial Content)

  - by Nikita Rybak

  Hi guys, I'm feeling completely stupid because I've spent two hours solving task which should be very simple and which I solved many times before. But now I'm not even sure in which direction to dig. I fail to fetch static content using ajax from local servers (Apache and Mongrel). I get responses 200 and 206 (depending on the server), empty response text (although Content-Length header is always correct), firebug shows request in red. Javascript is very generic, I'm getting same results even here: http://www.w3schools.com/ajax/tryit.asp?filename=tryajax_first (just change document location to 'http://localhost:3000/whatever') So, it's probably not the cause. Well, now I'm out of ideas. I can also post http headers, if it'll help. Thanks! Response Headers Connection close Date Sat, 01 May 2010 21:05:23 GMT Last-Modified Sun, 18 Apr 2010 19:33:26 GMT Content-Type text/html Content-Length 7466 Request Headers Host localhost:3000 User-Agent Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3 Accept text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language en-us,en;q=0.5 Accept-Encoding gzip,deflate Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive 115 Connection keep-alive Referer http://www.w3schools.com/ajax/tryit_view.asp Origin http://www.w3schools.com Response Headers Date Sat, 01 May 2010 21:54:59 GMT Server Apache/2.2.14 (Unix) mod_ssl/2.2.14 OpenSSL/0.9.8l DAV/2 mod_jk/1.2.28 Etag "3d5cbdb-fb4-4819c460d4a40" Accept-Ranges bytes Content-Length 4020 Cache-Control max-age=7200, public, proxy-revalidate Expires Sat, 01 May 2010 23:54:59 GMT Content-Range bytes 0-4019/4020 Keep-Alive timeout=5, max=100 Connection Keep-Alive Content-Type application/javascript Request Headers Host localhost User-Agent Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3 Accept text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language en-us,en;q=0.5 Accept-Encoding gzip,deflate Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive 115 Connection keep-alive Origin null UPDATED: I've found a problem, it was about cross-domain requests. I knew that there are restrictions, but thought they're relaxed for local filesystem and local servers. (and expected more descriptive error message, anyway) Thanks everybody!

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• Php miniserver downloader bandwidth

  - by snikolov

  $httpsock = @socket_create_listen("9090"); if (!$httpsock) { print "Socket creation failed!\n"; exit; } while (1) { $client = socket_accept($httpsock); $input = trim(socket_read ($client, 4096)); $input = explode(" ", $input); $input = $input[1]; $fileinfo = pathinfo($input); switch ($fileinfo['extension']) { default: $mime = "text/html"; } if ($input == "/") { $input = "index.html"; } $input = ".$input"; if (file_exists($input) && is_readable($input)) { echo "Serving $input\n"; $contents = file_get_contents($input); $output = "HTTP/1.0 200 OK\r\nServer: APatchyServer\r\nConnection: close\r\nContent-Type: $mime\r\n\r\n$contents"; } else { //$contents = "The file you requested doesn't exist. Sorry!"; //$output = "HTTP/1.0 404 OBJECT NOT FOUND\r\nServer: BabyHTTP\r\nConnection: close\r\nContent-Type: text/html\r\n\r\n$contents"; $filename = "dada"; $file = fopen($filename, 'r'); $filesize = filesize($filename); $buffer = fread($file, $filesize); $send = array("Output"=$buffer,"filesize"=$filesize,"filename"=$filename); $file = $send['filename']; $filesize = $send['filesize']; $output = 'HTTP/1.0 200 OK\r\n'; $output .= "Content-type: application/octet-stream\r\n"; $output .= 'Content-Disposition: attachment; filename="'.$file.'"\r\n'; $output .= "Content-Length:$filesize\r\n"; $output .= "Accept-Ranges: bytes\r\n"; $output .= "Cache-Control: private\n\n"; $output .= $send['Output']; $output .= "Content-Transfer-Encoding: binary"; $output .= "Connection: Keep-Alive\r\n"; } socket_write($client, $output); socket_close ($client); } socket_close ($httpsock); Hello i have create a code here to work as a webserver downloader the client can request files and download, i got it working at last however, i would like to know if the webserver can show much bandwidth the user request via sockets, perl has the same option as php but its more hardcore than php, i dont understand much about perl, i even saw that a miniwebserver can show much the client user pulls from the server would it be possible that you can assist me with this coding, i much aprreciate it thank you guys.

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• How To Create A Download Quota.

  - by snikolov

  I need to create an handy file down loader which will count the amount of bytes downloaded and stop when it has exceed a preset limit. i need to mirror some files but i only have 7 gb per moth of bandwidth and i dont want to exceed the limit. Example limits can be in bytes or number of files, each user has their own limit, as well as a limit for Download Quota itself. So if you set a limit of 2 gigabytes for Download Quota, downloads stop at 2 gigabytes, even if you have 3 users with a limit of 1 gigabyte each. if ($range) { //pass client Range header to rapidshare // _insert($range); $cookie .= "\r\nRange: $range"; $multipart = true; header("X-UR-RANGE-Range: $range"); } //octet-stream + attachment => client always stores file header('Content-type: application/octet-stream'); header('Content-Disposition: attachment; filename="' . $fn . '"'); //always included so clients know this script supports resuming header("Accept-Ranges: bytes"); //awful hack to pass rapidshare the premium cookie $user_agent = ini_get("user_agent"); ini_set("user_agent", $user_agent . "\r\nCookie: enc=$cookie"); $httphandle = fopen($url, "r"); $headers = stream_get_meta_data($httphandle); //let's check the return header of rapidshare for range / length indicators //we'll just pass these to the client foreach ($headers["wrapper_data"] as $header) { $header = trim($header); if (substr(strtolower($header), 0, strlen("content-range")) == "content-range") { // _insert($range); header($header); header("X-RS-RANGE-" . $header); $multipart = true; //content-range indicates partial download } elseif (substr(strtolower($header), 0, strlen("Content-Length")) == "content-length") { // _insert($range); header($header); header("X-RS-CL-" . $header); } } //now show the client he has a partial download if ($multipart) header('HTTP/1.1 206 Partial Content'); flush(); $download_rate = 100; while (!feof($httphandle)) { // send the current file part to the browser $var_stat = fread($httphandle, round($download_rate * 1024)); $var12 = strlen($var_stat); ////////////////////////////////// echo $var_stat; ///////////////////////////////// // flush the content to the browser flush(); // sleep one second sleep(1); }

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• Function Point Analysis -- a seriously overestimating technique?

  - by kizzx2

  I know questions about FPA has been asked numerous times before, but this time I'm taking a more analytical angle at it, backed up with data. 1. First, some data This question is based on a tutorial. He had a "Sample Count" section where he demonstrated it step by step. You can see some screenshots of his sample application here. In the end, he calculated the unadjusted FP to be 99. There is another article on InformIT with industry data on typical hour/FP. It ranges from 2 hours/FP to 27.4 hours/FP. Let's try to stick with 2 for the moment (since SO readers are probably the more efficient crowd :p). 2. Reality check!? Now just check out the screenshots again. Do a little math here 99 * 2 = 198 hours 198 hours / 40 hours per week = 5 weeks Seriously? That sample application is going to take 5 weeks to implement? Is it just my feeling that it wouldn't take any decent programmer longer than one week (I"m not even saying weekend) to have it completed? Now let's try estimating the cost of the project. We'll use New York's minimum wage at the moment (Wikipedia), which is $7.25 198 * 7.25 = $1435.5 From what I could see from the screenshots, this application is a small excel-improvement app. I could have bought MS Office Pro for 200 bucks which gives me greater interoperability (.xls files) and flexibility (spreadsheets). (For the record, that same Web site has another article discussing productivity. It seems like they typically use 4.2 hours/FP, which gives us even more shocking stats: 99 * 4.2 = 415 hours = 10 weeks = almost 3 whopping months! 415 hours * $7.25 = $3000 zomg (That's even assuming that all our poor coders get the minimum wage!) 3. Am I missing something here? Right now, I could come up with several possible explanation: FPA is really only suited for bigger projects (1000+ FPs) so it becomes extremely inaccurate at smaller scale. The hours/FP metric fluctuates abruptly from team to team, project to project. For a small project like this, we could have used something like 0.5 hour/FP or something. (Now this kind of makes the whole estimation thing pointless, unless my firm does the same type of projects for several years with the same team, not really common.) From my experience with several software metrics, Function Point is really not a lightweight metric. If the hour/FP thing fluctuates so much, then what's the point, maybe I could have gone with User Story Points which is a lot faster to get and arguably almost as uncertain. What would be the FP experts' answers to this?

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• PHP miniwebsever file download

  - by snikolov

  $httpsock = @socket_create_listen("9090"); if (!$httpsock) { print "Socket creation failed!\n"; exit; } while (1) { $client = socket_accept($httpsock); $input = trim(socket_read ($client, 4096)); $input = explode(" ", $input); $input = $input[1]; $fileinfo = pathinfo($input); switch ($fileinfo['extension']) { default: $mime = "text/html"; } if ($input == "/") { $input = "index.html"; } $input = ".$input"; if (file_exists($input) && is_readable($input)) { echo "Serving $input\n"; $contents = file_get_contents($input); $output = "HTTP/1.0 200 OK\r\nServer: APatchyServer\r\nConnection: close\r\nContent-Type: $mime\r\n\r\n$contents"; } else { //$contents = "The file you requested doesn't exist. Sorry!"; //$output = "HTTP/1.0 404 OBJECT NOT FOUND\r\nServer: BabyHTTP\r\nConnection: close\r\nContent-Type: text/html\r\n\r\n$contents"; function openfile() { $filename = "a.pl"; $file = fopen($filename, 'r'); $filesize = filesize($filename); $buffer = fread($file, $filesize); $array = array("Output"=$buffer,"filesize"=$filesize,"filename"=$filename); return $array; } $send = openfile(); $file = $send['filename']; $filesize = $send['filesize']; $output = 'HTTP/1.0 200 OK\r\n'; $output .= "Content-type: application/octet-stream\r\n"; $output .= 'Content-Disposition: attachment; filename="'.$file.'"\r\n'; $output .= "Content-Length:$filesize\r\n"; $output .= "Accept-Ranges: bytes\r\n"; $output .= "Cache-Control: private\n\n"; $output .= $send['Output']; $output .= "Content-Transfer-Encoding: binary"; $output .= "Connection: Keep-Alive\r\n"; } socket_write($client, $output); socket_close ($client); } socket_close ($httpsock); Hello, I am snikolov i am creating a miniwebserver with php and i would like to know how i can send the client a file to download with his browser such as firefox or internet explore i am sending a file to the user to download via sockets, but the cleint is not getting the filename and the information to download can you please help me here,if i declare the file again i get this error in my server Fatal error: Cannot redeclare openfile() (previously declared in C:\User s\fsfdsf\sfdsfsdf\httpd.php:31) in C:\Users\hfghfgh\hfghg\httpd.php on li ne 29, if its possible, i would like to know if the webserver can show much banwdidth the user request via sockets, perl has the same option as php but its more hardcore than php i dont understand much about perl, i even saw that a miniwebserver can show much the client user pulls from the server would it be possible that you can assist me with this coding, i much aprreciate it thank you guys.

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• Multiplying matrices: error: expected primary-expression before 'struct'

  - by justin

  I am trying to write a program that is supposed to multiply matrices using threads. I am supposed to fill the matrices using random numbers in a thread. I am compiling in g++ and using PTHREADS. I have also created a struct to pass the data from my command line input to the thread so it can generate the matrix of random numbers. The sizes of the two matrices are also passed in the command line as well. I keep getting: main.cpp:7: error: expected primary-expression before 'struct' my code @ line 7 =: struct a{ int Arow; int Acol; int low; int high; }; My inpust are : Sizes of two matrices ( 4 arguments) high and low ranges in which o generate the random numbers between. Complete code: [headers] using namespace std; void *matrixACreate(struct *); void *status; int main(int argc, char * argv[]) { int Arow = atoi(argv[1]); // Matrix A int Acol = atoi(argv[2]); // WxX int Brow = atoi(argv[3]); // Matrix B int Bcol = atoi(argv[4]); // XxZ, int low = atoi(argv[5]); // Range low int high = atoi(argv[6]); struct a{ int Arow; // Matrix A int Acol; // WxX int low; // Range low int high; }; pthread_t matrixAthread; //pthread_t matrixBthread; pthread_t runner; int error, retValue; if (Acol != Brow) { cout << " This matrix cannot be multiplied. FAIL" << endl; return 0; } error = pthread_create(&matrixAthread, NULL, matrixACreate, struct *a); //error = pthread_create(&matrixAthread, NULL, matrixBCreate, sendB); retValue = pthread_join(matrixAthread, &status); //retValue = pthread_join(matrixBthread, &status); return 0; } void matrixACreate(struct * a) { struct a *data = (struct a *) malloc(sizeof(struct a)); data->Arow = Arow; data->Acol = Acol; data->low = low; data->high = high; int range = ((high - low) + 1); cout << Arow << endl<< Acol << endl; }// just trying to print to see if I am in the thread

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• Techniques for querying a set of object in-memory in a Java application

  - by Edd Grant

  Hi All, We have a system which performs a 'coarse search' by invoking an interface on another system which returns a set of Java objects. Once we have received the search results I need to be able to further filter the resulting Java objects based on certain criteria describing the state of the attributes (e.g. from the initial objects return all objects where x.y z && a.b == c). The criteria used to filter the set of objects each time is partially user configurable, by this I mean that users will be able to select the values and ranges to match on but the attributes they can pick from will be a fixed set. The data sets are likely to contain <= 10,000 objects for each search. The search will be executed manually by the application user base probably no more than 2000 times a day (approx). It's probably worth mentioning that all the objects in the result set are known domain object classes which have Hibernate and JPA annotations describing their structure and relationship. Off the top of my head I can think of 3 ways of doing this: For each search persist the initial result set objects in our database, then use Hibernate to re-query them using the finer grained criteria. Use an in-memory Database (such as hsqldb?) to query and refine the initial result set. Write some custom code which iterates the initial result set and pulls out the desired records. Option 1 seems to involve a lot of toing and froing across a network to a physical Database (Oracle 10g) which might result in a lot of network and disk activity. It would also require the results from each search to be isolated from other result sets to ensure that different searches don't interfere with each other. Option 2 seems like a good idea in principle as it would allow me to do the finer query in memory and would not require the persistence of result data which would only be discarded after the search was complete. Gut feeling is that this could be pretty performant too but might result in larger memory overheads (which is fine as we can be pretty flexible on the amount of memory our JVM gets). Option 3 could be very performant but is something I would like to avoid as any code we write would require such careful testing that the time taken to acheive something flexible and robust enough would probably be prohibitive. I don't have time to prototype all 3 ideas so I am looking for comments people may have on the 3 options above, plus any further ideas I have not considered, to help me decide which idea might be most suitable. I'm currently leaning toward option 2 (in memory database) so would be keen to hear from people with experience of querying POJOs in memory too. Hopefully I have described the situation in enough detail but don't hesitate to ask if any further information is required to better understand the scenario. Cheers, Edd

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• Finding open contiguous blocks of time for every day of a month, fast

  - by Chris

  I am working on a booking availability system for a group of several venues, and am having a hard time generating the availability of time blocks for days in a given month. This is happening server-side in PHP, but the concept itself is language agnostic -- I could be doing this in JS or anything else. Given a venue_id, month, and year (6/2012 for example), I have a list of all events occurring in that range at that venue, represented as unix timestamps start and end. This data comes from the database. I need to establish what, if any, contiguous block of time of a minimum length (different per venue) exist on each day. For example, on 6/1 I have an event between 2:00pm and 7:00pm. The minimum time is 5 hours, so there's a block open there from 9am - 2pm and another between 7pm and 12pm. This would continue for the 2nd, 3rd, etc... every day of June. Some (most) of the days have nothing happening at all, some have 1 - 3 events. The solution I came up with works, but it also takes waaaay too long to generate the data. Basically, I loop every day of the month and create an array of timestamps for each 15 minutes of that day. Then, I loop the time spans of events from that day by 15 minutes, marking any "taken" timeslot as false. Remaining, I have an array that contains timestamp of free time vs. taken time: //one day's array after processing through loops (not real timestamps) array( 12345678=>12345678, // <--- avail 12345878=>12345878, 12346078=>12346078, 12346278=>false, // <--- not avail 12346478=>false, 12346678=>false, 12346878=>false, 12347078=>12347078, // <--- avail 12347278=>12347278 ) Now I would need to loop THIS array to find continuous time blocks, then check to see if they are long enough (each venue has a minimum), and if so then establish the descriptive text for their start and end (i.e. 9am - 2pm). WHEW! By the time all this looping is done, the user has grown bored and wandered off to Youtube to watch videos of puppies; it takes ages to so examine 30 or so days. Is there a faster way to solve this issue? To summarize the problem, given time ranges t1 and t2 on day d, how can I determine the remaining time left in d that is longer than the minimum time block m. This data is assembled on demand via AJAX as the user moves between calendar months. Results are cached per-page-load, so if the user goes to July a second time, the data that was generated the first time would be reused. Any other details that would help, let me know. Edit Per request, the database structure (or the part that is relevant here) *events* id (bigint) title (varchar) *event_times* id (bigint) event_id (bigint) venue_id (bigint) start (bigint) end (bigint) *venues* id (bigint) name (varchar) min_block (int) min_start (varchar) max_start (varchar)

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• Cisco ASA 5505 site to site IPSEC VPN won't route from multiple LANs

  - by franklundy

  Hi I've set up a standard site to site VPN between 2 ASA 5505s (using the wizard in ASDM) and have the VPN working fine for traffic between Site A and Site B on the directly connected LANs. But this VPN is actually to be used for data originating on LAN subnets that are one hop away from the directly connected LANs. So actually there is another router connected to each ASA (LAN side) that then route to two completely different LAN ranges, where the clients and servers reside. At the moment, any traffic that gets to the ASA that has not originated from the directly connected LAN gets sent straight to the default gateway, and not through the VPN. I've tried adding the additional subnets to the "Protected Networks" on the VPN, but that has no effect. I have also tried adding a static route to each ASA trying to point the traffic to the other side, but again this hasn't worked. Here is the config for one of the sites. This works for traffic to/from the 192.168.144.x subnets perfectly. What I need is to be able to route traffic from 10.1.0.0/24 to 10.2.0.0/24 for example. ASA Version 8.0(3) ! hostname Site1 enable password ** encrypted names name 192.168.144.4 Site2 ! interface Vlan1 nameif inside security-level 100 ip address 192.168.144.2 255.255.255.252 ! interface Vlan2 nameif outside security-level 0 ip address 10.78.254.70 255.255.255.252 (this is a private WAN circuit) ! interface Ethernet0/0 switchport access vlan 2 ! interface Ethernet0/1 ! interface Ethernet0/2 ! interface Ethernet0/3 ! interface Ethernet0/4 ! interface Ethernet0/5 ! interface Ethernet0/6 ! interface Ethernet0/7 ! passwd ** encrypted ftp mode passive access-list inside_access_in extended permit ip any any access-list outside_access_in extended permit icmp any any echo-reply access-list outside_1_cryptomap extended permit ip 192.168.144.0 255.255.255.252 Site2 255.255.255.252 access-list inside_nat0_outbound extended permit ip 192.168.144.0 255.255.255.252 Site2 255.255.255.252 pager lines 24 logging enable logging asdm informational mtu inside 1500 mtu outside 1500 icmp unreachable rate-limit 1 burst-size 1 asdm image disk0:/asdm-603.bin no asdm history enable arp timeout 14400 global (outside) 1 interface nat (inside) 0 access-list inside_nat0_outbound nat (inside) 1 0.0.0.0 0.0.0.0 access-group inside_access_in in interface inside access-group outside_access_in in interface outside route outside 0.0.0.0 0.0.0.0 10.78.254.69 1 timeout xlate 3:00:00 timeout conn 1:00:00 half-closed 0:10:00 udp 0:02:00 icmp 0:00:02 timeout sunrpc 0:10:00 h323 0:05:00 h225 1:00:00 mgcp 0:05:00 mgcp-pat 0:05:00 timeout sip 0:30:00 sip_media 0:02:00 sip-invite 0:03:00 sip-disconnect 0:02:00 timeout uauth 0:05:00 absolute dynamic-access-policy-record DfltAccessPolicy aaa authentication ssh console LOCAL http server enable http 0.0.0.0 0.0.0.0 outside http 192.168.1.0 255.255.255.0 inside no snmp-server location no snmp-server contact snmp-server enable traps snmp authentication linkup linkdown coldstart crypto ipsec transform-set ESP-3DES-SHA esp-3des esp-sha-hmac crypto map outside_map 1 match address outside_1_cryptomap crypto map outside_map 1 set pfs crypto map outside_map 1 set peer 10.78.254.66 crypto map outside_map 1 set transform-set ESP-3DES-SHA crypto map outside_map interface outside crypto isakmp enable outside crypto isakmp policy 10 authentication pre-share encryption 3des hash sha group 2 lifetime 86400 no crypto isakmp nat-traversal telnet timeout 5 ssh 0.0.0.0 0.0.0.0 outside ssh timeout 5 console timeout 0 management-access inside threat-detection basic-threat threat-detection statistics port threat-detection statistics protocol threat-detection statistics access-list group-policy DfltGrpPolicy attributes vpn-idle-timeout none username enadmin password * encrypted privilege 15 tunnel-group 10.78.254.66 type ipsec-l2l tunnel-group 10.78.254.66 ipsec-attributes pre-shared-key * ! ! prompt hostname context

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• Why do GPUs overheat?

  - by JAD

  About a year ago, I added a 9800GT (1 GB version) and a Corsair CX500 PSU to an HP M8000N computer. A few weeks ago, the HDD overheated and I decided to transfer the GPU & PSU to a new build, which consists of: i3 @ 3.3Ghz Gigabyte H61 Micro ATX Mobo 4GB RAM 500GB WD HDD DVD RW Drive Cooler Master Elite 430 Tower Once I had Win7 up and running, I installed all the essential drivers that came with the Gigabyte Mobo CD. However, whenever I tried installing the Graphics Media Accelerator driver, the computer would crash and enter an endless boot sequence on the next startup. I skipped installing this driver and installed the CD driver for the 9800GT, which by now is a year old. Everything was working fine, WEI rated my GPU at 6.6 graphics & aero performance. However, after updating my Nvidia drivers to the latest, the WEI dropped my rating to 3.3 for Aero, and 4.7 for graphics performance. Just to make sure that everything was ok, I ran Bad Company 2 on medium settings. The first few minutes ran just fine at a smooth framerate, so I dismissed this as Windows being Windows. About 6 hours later, I ran BC2 again. This time I averaged anywhere from 2-5 FPS. I checked the GPU temperature through GPU-Z, and it came back as 120C. The problem with this, is that the computer was on for six hours up to that point. Wouldn't the card have experienced a reactor core meltdown a lot sooner than that? Granted, the computer was "sleeping" some of the time, but still... The next day I took out a temperature gun and ran some tests. I would point the laser at a very specific area on the reverse side of the card (not the fan or "front"), and compare the temp reading with GPU-Z. After leaving the system on idle on idle for a few minutes, I ran BC2 twice. Here are the results: GPU-Z Reading / Temp Gun Reading / Time Null / 22.3°C / Comp is Off 53°C / 33.5°C / 1:49 78°C / 46°C / 1:53 - (First BC2 run; good framerate) 102°C / 64.6°C / 2:01 - (System is again on idle) 113°C / 64.8°C / 2:10 119°C / 71.8°C / 2:17 - (Second BC2 run; poor framerate) I should also mention that I also took a temp recording of another part of the GPU from 2:01-2:17. The temp in this area jumped from 75°C to 82.9°C in that time frame. This pretty much confirms that GPU-Z is reporting the temperature accurately, and the card is overheating. But I'd like to know why; the cars is doing nothing and still the temperature climbs at a steady rate. I thoroughly cleaned the GPU and PSU when I salvaged them from the old HP M8000N computer with a can of compressed air, dust cant be the issue. Similarly, the rest of the computer is brand new. I installed various Nvidia drivers, but no luck. It seems strange to me that a year-old card is suddenly failing on me; aren't they supposed to last at least two years? Could this be a driver issue? Is the motherboard faulty? Could the PSU be overfeeding the card on voltage? Neither case seems likely, as the CPU, RAM and otherwise the rest of the comp has worked flawlessly and has stayed well within respectable temp ranges (the i3 lingers around 50C, the HDD stays at 30C, so does the PSU). How can I pinpoint the issue?

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• Varnish cached 'MISS status' object?

  - by Hesey

  My site uses nginx, varnish, jboss. And some url will be cached by varnish, it depends a response header from jboss. The first time, jboss tells varnish doesn't cache this url. Then the second request, jboss tells varnish to cache, but varnish won't cache it. I used varnishstat and found that 1 object is cached in Varnish, is that the 'MISS status' object? I remove grace code and the problem still exists. When I PURGE this url, varnish works fine and cache the url then. But I can't PURGE so much urls every startup time, how can I fix this? The configuration: acl local { "localhost"; } backend default { .host = "localhost"; .port = "8080"; .probe = { .url = "/preload.htm"; .interval = 3s; .timeout = 1s; .window = 5; .threshold = 3; } } sub vcl_deliver { if (req.request == "PURGE") { remove resp.http.X-Varnish; remove resp.http.Via; remove resp.http.Age; remove resp.http.Content-Type; remove resp.http.Server; remove resp.http.Date; remove resp.http.Accept-Ranges; remove resp.http.Connection; set resp.http.keeplive="true"; } else { if (obj.hits > 0) { set resp.http.X-Cache = "HIT"; } else { set resp.http.X-Cache = "MISS"; } } } sub vcl_recv { if(req.url ~ "/check.htm"){ error 404 "N"; } if( req.http.host ~ "store." || req.request == "POST"){ return (pipe); } if (req.backend.healthy) { set req.grace = 30s; } else { set req.grace = 10m; } set req.http.x-cacheKey = "0"; if(req.url ~ "/shop/view_shop.htm" || req.url ~ "/shop/viewShop.htm" || req.url ~ "/index.htm"){ if(req.url ~ "search=y"){ set req.http.x-cacheKey = req.http.host + "/search.htm"; }else if(req.url !~ "bbs=y" && req.url !~ "shopIntro=y" && req.url !~ "shop_intro=y"){ set req.http.x-cacheKey = req.http.host + "/index.htm"; } }else if(req.url ~ "/search"){ set req.http.x-cacheKey = req.http.host + "/search.htm"; } if( req.http.x-cacheKey == "0" && req.url !~ "/i/"){ return (pipe); } if (req.request == "PURGE") { if (client.ip ~ local) { return (lookup); } else { error 405 "Not allowed."; } } if (req.url ~ "/i/") { set req.http.x-shop-url = req.original_url; }else { unset req.http.cookie; } } sub vcl_fetch { set beresp.grace = 10m; #unset beresp.http.x-cacheKey; if (req.url ~ "/i/" || req.url ~ "status" ){ set beresp.ttl = 0s; /* ttl=0 for dynamic content */ } else if(beresp.http.x-varnish-cache != "1"){ set beresp.do_esi = true; /* Do ESI processing */ set beresp.ttl = 0s; unset beresp.http.set-cookie; } else { set beresp.do_esi = true; /* Do ESI processing */ set beresp.ttl = 1800s; unset beresp.http.set-cookie; } } sub vcl_hash { hash_data(req.http.x-cacheKey); return (hash); } sub vcl_error { if (req.request == "PURGE") { return (deliver); } else { set obj.http.Content-Type = "text/html; charset=gbk"; synthetic {"<!--ve-->"}; return (deliver); } } sub vcl_hit { if (req.request == "PURGE") { set obj.ttl = 0s; error 200 "Purged."; } } sub vcl_miss { if (req.request == "PURGE") { error 404 "N"; } }

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• Identifying the cause of my DNS failure (domain not propagating)

  - by thejartender

  I have set up a DNS server with the help of two helpful tutorials: http://linuxconfig.org/linux-dns-server-bind-configuration http://ulyssesonline.com/2007/11/07/how-to-setup-a-dns-server-in-ubuntu/ I am using: Ubuntu Bind9 and had issues I tried negating on my own thanks to a question I posted here earlier that pointed out my mistake of using rfc 1918 addresses in my previous SOA record: $TTL 3D @ IN SOA ns.thejarbar.org. email. ( 13112012 28800 3600 604800 38400 ); thejarbar.org. IN A 10.0.0.42 @ IN NS ns.thejarbar,org. yuccalaptop IN A 10.0.0.19 ns IN A 10.0.0.42 gw IN A 10.0.0.138 www IN CNAME thejarbar.org. $TTL 600 0.0.10.in-addr.arpa. IN SOA ns.thejarbar.org. email. ( 13112012 28800 3600 604800 38400 ); 0.0.10.in-addr.arpa. IN NS ns.thejarbar.org. 42 IN PTR thejarbar.org. 19 IN PTR yuccalaptop.thejarbar.org. 138 IN PTR gw.thejarbar.org. I read the ranges that are used under rfc 1918 and modified my routers resource pool to assign LAN devices IP(s) within the 30.0.0.0 range and now modified my SOA to: $TTL 600 @ IN SOA ns.thejarbar.org. email. ( 13112012 28800 3600 604800 38400 ); thejarbar.org. IN A 30.0.0.42 @ IN NS ns.thejarbar,org. yuccalaptop IN A 10.0.0.19 ns IN A 30.0.0.42 gw IN A 30.0.0.138 www IN CNAME thejarbar.org. $TTL600 0.0.10.in-addr.arpa. IN SOA ns.thejarbar.org. email. ( 13112012 28800 3600 604800 38400 ); 0.0.30.in-addr.arpa. IN NS ns.thejarbar.org. 42 IN PTR thejarbar.org. 19 IN PTR yuccalaptop.thejarbar.org. 138 IN PTR gw.thejarbar.org. I can ping my nameserverver ns.thejarbar.organd it gives me the correct isp IP address, but my domain never seems to propagate to my nameserver. I have searched for a concise tutorial that covers setting up a DNS with a nameserver that hosts (my) or the site. I am fully aware that this is not recommended and am using this for my learning purposes. Getting to the question, due to the lack of information in tutorials I looked at (nothing about rfc 1918 and no example of swapping these with ISP IP) is my router modification going to help me as it does not seem to be. I have also tried as recommended using my ISP IP instead of the values I posted. My site never propagated to my nameserver. What could be causing this? I have run dig thejarbar.org @88.89.190.171 and get an authorative response. Can anyone assist me with the final steps I may be missing here?

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• I have a NGINX server configured to work with node.js, but many times a file of 1.03MB of js is not loaded by various browser and various pc

  - by Totty

  I'm using this in a local LAN so it should be quite fast. The nginx server use the node.js server to serve static files, so it must pass throught node.js to download the files, but that is not a problem when I'm not using the nginx. In chrome with debugger on I can see that the status is: 206 - partial content and it only has downloaded 31KB of 1.03MB. After 1.1 min it turns red and the status failed. Waiting time: 6ms Receiving: 1.1 min The headers in google chrom: Request URL:http://192.168.1.16/production/assembly/script/production.js Request Method:GET Status Code:206 Partial Content Request Headersview source Accept:*/* Accept-Charset:ISO-8859-1,utf-8;q=0.7,*;q=0.3 Accept-Encoding:gzip,deflate,sdch Accept-Language:pt-PT,pt;q=0.8,en-US;q=0.6,en;q=0.4 Connection:keep-alive Cookie:connect.sid=s%3Abls2qobcCaJ%2FyBNZwedtDR9N.0vD4Fi03H1bEdCszGsxIjjK0lZIjJhLnToWKFVxZOiE Host:192.168.1.16 If-Range:"1081715-1350053827000" Range:bytes=16090-16090 Referer:http://192.168.1.16/production/assembly/ User-Agent:Mozilla/5.0 (Windows NT 6.0) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.94 Safari/537.4 Response Headersview source Accept-Ranges:bytes Cache-Control:public, max-age=0 Connection:keep-alive Content-Length:1 Content-Range:bytes 16090-16090/1081715 Content-Type:application/javascript Date:Mon, 15 Oct 2012 09:18:50 GMT ETag:"1081715-1350053827000" Last-Modified:Fri, 12 Oct 2012 14:57:07 GMT Server:nginx/1.1.19 X-Powered-By:Express My nginx configurations: File 1: user totty; worker_processes 4; pid /var/run/nginx.pid; events { worker_connections 768; # multi_accept on; } http { ## # Basic Settings ## sendfile on; tcp_nopush on; tcp_nodelay on; keepalive_timeout 65; types_hash_max_size 2048; # server_tokens off; # server_names_hash_bucket_size 64; # server_name_in_redirect off; include /etc/nginx/mime.types; default_type application/octet-stream; ## # Logging Settings ## access_log /home/totty/web/production01_server/node_modules/production/_logs/_NGINX_access.txt; error_log /home/totty/web/production01_server/node_modules/production/_logs/_NGINX_error.txt; ## # Gzip Settings ## gzip on; gzip_disable "msie6"; # gzip_vary on; # gzip_proxied any; # gzip_comp_level 6; # gzip_buffers 16 8k; # gzip_http_version 1.1; # gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript; ## # nginx-naxsi config ## # Uncomment it if you installed nginx-naxsi ## #include /etc/nginx/naxsi_core.rules; ## # nginx-passenger config ## # Uncomment it if you installed nginx-passenger ## #passenger_root /usr; #passenger_ruby /usr/bin/ruby; ## # Virtual Host Configs ## autoindex on; include /home/totty/web/production01_server/_deployment/nginxConfigs/server/*; } File that is included by the previous file: server { # custom location for entry # using only "/" instead of "/production/assembly" it # would allow you to go to "thatip/". In this way # we are limiting to "thatip/production/assembly/" location /production/assembly/ { # ip and port used in node.js proxy_pass http://127.0.0.1:3000/; } location /production/assembly.mongo/ { proxy_pass http://127.0.0.1:9000/; proxy_redirect off; } location /production/assembly.logs/ { autoindex on; alias /home/totty/web/production01_server/node_modules/production/_logs/; } }

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• Is there a bug with Apache 2.2 and content filters (and maybe mod_proxy)?

  - by asciiphil

  I'm running Apache 2.2.15-29 on RHEL 6 (actually Scientific Linux 6.4) and I'm trying to set up a reverse proxy with content rewriting so all of the links on the proxied web pages are rewritten to reference the proxy host. I'm running into a problem with some of the content rewriting and I'd like to know if this is a bug or if I'm doing something wrong (and how to do it right, if applicable). I'm proxying a subdirectory on an internal host (internal.example.com/foo) onto the root of an external host (external.example.com). I need to rewrite HTML, CSS, and Javascript content to fix all of the URLs. I'm also hosting some content locally on the external host, which I don't think is a problem but I'm mentioning here for completeness. My httpd.conf looks roughly like this: <VirtualHost *:80> ServerName external.example.com ServerAlias example.com # Serve all local content directly, reverse-proxy all unknown URIs. RewriteEngine On RewriteRule ^(/(index.html?)?)?$ http://internal.example.com/foo/ [P] RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME} -f [OR] RewriteCond %{DOCUMENT_ROOT}%{REQUEST_FILENAME} -d RewriteRule ^.*$ - [L] RewriteRule ^/~ - [L] RewriteRule ^(.*)$ http://internal.example.com$1 [P] # Standard header rewriting. ProxyPassReverse / http://internal.example.com/foo/ ProxyPassReverseCookieDomain internal.example.com external.example.com ProxyPassReverseCookiePath /foo/ / # Strip any Accept-Encoding: headers from the client so we can process the pages # as plain text. RequestHeader unset Accept-Encoding # Use mod_proxy_html to fix URLs in text/html content. ProxyHTMLEnable On ProxyHTMLURLMap http://internal.example.com/foo/ / ProxyHTMLURLMap http://internal.example.com/foo / ProxyHTMLURLMap /foo/ / ## Use mod_substitute to fix URLs in CSS and Javascript #<Location /> # AddOutputFilterByType SUBSTITUTE text/css # AddOutputFilterByType SUBSTITUTE text/javascript # Substitute "s|http://internal.example.com/foo/|/|nq" #</Location> # Use mod_ext_filter to fix URLs in CSS and Javascript ExtFilterDefine fixurlcss mode=output intype=text/css cmd="/bin/sed -rf /etc/httpd/fixurls" ExtFilterDefine fixurljs mode=output intype=text/javascript cmd="/bin/sed -rf /etc/httpd/fixurls" <Location /> SetOutputFilter fixurlcss;fixurljs </Location> </VirtualHost> The text/html rewriting works just fine. When I use either mod_substitute or mod_ext_filter, the external server sends the pages as Transfer-Encoding: chunked, sends all of the data, and then closes the connection without sending the final, zero-length chunk. Some HTTP clients are unhappy with this. (Chrome won't process any content sent in this way, for example, so the pages don't get CSS applied to them.) Here's a sample wget session: $ wget -O /dev/null -S http://external.example.com/include/jquery.js --2013-11-01 11:36:36-- http://external.example.com/include/jquery.js Resolving external.example.com (external.example.com)... 192.168.0.1 Connecting to external.example.com (external.example.com)|192.168.0.1|:80... connected. HTTP request sent, awaiting response... HTTP/1.1 200 OK Date: Fri, 01 Nov 2013 15:36:36 GMT Server: Apache Last-Modified: Tue, 29 Oct 2013 13:09:10 GMT ETag: "1d60026-187b8-4e9e0ec273e35" Accept-Ranges: bytes Vary: Accept-Encoding X-UA-Compatible: IE=edge,chrome=1 Content-Type: text/javascript;charset=utf-8 Connection: close Transfer-Encoding: chunked Length: unspecified [text/javascript] Saving to: `/dev/null' [ <=> ] 100,280 --.-K/s in 0.005s 2013-11-01 11:36:37 (19.8 MB/s) - Read error at byte 100280 (Success).Retrying. --2013-11-01 11:36:38-- (try: 2) http://external.example.com/include/jquery.js Connecting to external.example.com (external.example.com)|192.168.0.1|:80... connected. HTTP request sent, awaiting response... HTTP/1.1 416 Requested Range Not Satisfiable Date: Fri, 01 Nov 2013 15:36:38 GMT Server: Apache Vary: Accept-Encoding Content-Type: text/html;charset=utf-8 Content-Length: 260 Connection: close The file is already fully retrieved; nothing to do. Am I doing something wrong? Am I hitting some sort of Apache bug? What do I need to do to get it working? (Note that I'd prefer solutions that work within RHEL-6-packaged RPMs and upgrading to Apache 2.4 would be a last resort, as we have a lot of infrastructure built around 2.2 on this system at the moment.)

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• Convert from apache rewrite to nginx

  - by Linux Intel

  I want to convert from apache rewrite modules to nginx RewriteCond %{QUERY_STRING} mosConfig_[a-zA-Z_]{1,21}(=|\%3D) [OR] RewriteCond %{QUERY_STRING} base64_encode.*\(.*\) [OR] RewriteCond %{QUERY_STRING} (\<|%3C).*script.*(\>|%3E) [NC,OR] RewriteCond %{QUERY_STRING} GLOBALS(=|\[|\%[0-9A-Z]{0,2}) [OR] RewriteCond %{QUERY_STRING} _REQUEST(=|\[|\%[0-9A-Z]{0,2}) RewriteCond %{QUERY_STRING} SELECT(=|\[|\%[0-9A-Z]{0,2}) [OR] RewriteCond %{QUERY_STRING} UNION(=|\[|\%[0-9A-Z]{0,2}) [OR] RewriteCond %{QUERY_STRING} UPDATE(=|\[|\%[0-9A-Z]{0,2}) [OR] RewriteRule ^([^.]*)/?$ index.php [L] RewriteRule ^domain/trial/cms$ index/index.php?%{QUERY_STRING} [L] RewriteCond %{HTTP:Range} ([a-z]+) [NC] RewriteRule ([0-9_\-]+)flv$ http://www.domain.com [R,L] RewriteCond %{ENV:byte-ranges-specifier} !^$ RewriteRule ([0-9_\-]+)flv$ http://www.domain.com [R,L] RewriteCond %{HTTP_USER_AGENT} !^Mozilla/5 [NC] RewriteCond %{HTTP_USER_AGENT} !^Mozilla/4 [NC] RewriteCond %{HTTP_USER_AGENT} !^Opera [NC] RewriteRule ([0-9_\-]+)flv$ http://www.domain.com [R,L] RewriteRule ^$ index/index.php?%{QUERY_STRING} [L] RewriteCond %{SCRIPT_FILENAME} !sss.php [NC] RewriteCond %{SCRIPT_FILENAME} !m-administrator [NC] RewriteRule ^([^/^.]*)$ sss.php?encrypted=$1&%{QUERY_STRING} [L] RewriteCond %{SCRIPT_FILENAME} !sss.php [NC] RewriteCond %{SCRIPT_FILENAME} !m-administrator [NC] RewriteRule ^([^/^.]*)/([^/^.]*)$ sss.php?tab=$1&page=$2&%{QUERY_STRING} [L] RewriteCond %{SCRIPT_FILENAME} !sss.php [NC] RewriteCond %{SCRIPT_FILENAME} !m-administrator [NC] RewriteRule ^([^/^.]*)/([^/^.]*)/([^.]*)$ sss.php?tab=$1&page=$2&queryString=$3&%{QUERY_STRING} [L] RewriteCond %{SCRIPT_FILENAME} !sss.php [NC] RewriteCond %{SCRIPT_FILENAME} !security.php [NC] RewriteRule ^([^/]*)$ index/$1?%{QUERY_STRING} [L] I tried to convert it by online tools such as : http://www.anilcetin.com/convert-apache-htaccess-to-nginx/ but it didn't convert it correctly. The conversion output is : if ($args ~ "mosConfig_[a-zA-Z_]{1,21}(=|%3D)"){ set $rule_0 1; } if ($args ~ "base64_encode.*(.*)"){ set $rule_0 1; } if ($args ~* "(<|%3C).*script.*(>|%3E)"){ set $rule_0 1; } if ($args ~ "GLOBALS(=|[|%[0-9A-Z]{0,2})"){ set $rule_0 1; } if ($args ~ "_REQUEST(=|[|%[0-9A-Z]{0,2})"){ set $rule_0 1; } if ($args ~ "SELECT(=|[|%[0-9A-Z]{0,2})"){ set $rule_0 1; } if ($args ~ "UNION(=|[|%[0-9A-Z]{0,2})"){ set $rule_0 1; } if ($args ~ "UPDATE(=|[|%[0-9A-Z]{0,2})"){ set $rule_0 1; } if ($rule_0 = "1"){ rewrite ^/([^.]*)/?$ /index.php last; } if ($rule_1 = ""){ rewrite ^/domain/trial/cms$ /index/index.php?$args last; } if ($http_range ~* "([a-z]+)"){ set $rule_2 1$rule_2; } if ($rule_2 = "1"){ rewrite /([0-9_-]+)flv$ http://www.domain.com redirect; } #ignored: condition 0 if ($rule_3 = "1"){ rewrite /([0-9_-]+)flv$ http://www.domain.com redirect; } if ($http_user_agent !~* "^Mozilla/5"){ set $rule_4 1$rule_4; } if ($http_user_agent !~* "^Mozilla/4"){ set $rule_4 2$rule_4; } if ($http_user_agent !~* "^Opera"){ set $rule_4 3$rule_4; } if ($rule_4 = "321"){ rewrite /([0-9_-]+)flv$ http://www.domain.com redirect; } if ($rule_5 = ""){ rewrite ^/$ /index/index.php?$args last; } if ($uri !~* "sss.php"){ set $rule_6 1$rule_6; } if ($uri !~* "m-administrator"){ set $rule_6 2$rule_6; } if ($rule_6 = "21"){ rewrite ^/([^/^.]*)$ /sss.php?encrypted=$1&$args last; } if ($uri !~* "sss.php"){ set $rule_7 1$rule_7; } if ($uri !~* "m-administrator"){ set $rule_7 2$rule_7; } if ($rule_7 = "21"){ rewrite ^/([^/^.]*)/([^/^.]*)$ /sss.php?tab=$1&page=$2&$args last; } if ($uri !~* "sss.php"){ set $rule_8 1$rule_8; } if ($uri !~* "m-administrator"){ set $rule_8 2$rule_8; } if ($rule_8 = "21"){ rewrite ^/([^/^.]*)/([^/^.]*)/([^.]*)$ /sss.php?tab=$1&page=$2&queryString=$3&$args last; } if ($uri !~* "sss.php"){ set $rule_9 1$rule_9; } if ($uri !~* "security.php"){ set $rule_9 2$rule_9; } if ($rule_9 = "21"){ rewrite ^/([^/]*)$ /index/$1?$args last; } Please help me with the proper conversion result for nginx in order to work perfectly.

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• Session memory – who’s this guy named Max and what’s he doing with my memory?

  - by extended_events

  SQL Server MVP Jonathan Kehayias (blog) emailed me a question last week when he noticed that the total memory used by the buffers for an event session was larger than the value he specified for the MAX_MEMORY option in the CREATE EVENT SESSION DDL. The answer here seems like an excellent subject for me to kick-off my new “401 – Internals” tag that identifies posts where I pull back the curtains a bit and let you peek into what’s going on inside the extended events engine. In a previous post (Option Trading: Getting the most out of the event session options) I explained that we use a set of buffers to store the event data before  we write the event data to asynchronous targets. The MAX_MEMORY along with the MEMORY_PARTITION_MODE defines how big each buffer will be. Theoretically, that means that I can predict the size of each buffer using the following formula: max memory / # of buffers = buffer size If it was that simple I wouldn’t be writing this post. I’ll take “boundary” for 64K Alex For a number of reasons that are beyond the scope of this blog, we create event buffers in 64K chunks. The result of this is that the buffer size indicated by the formula above is rounded up to the next 64K boundary and that is the size used to create the buffers. If you think visually, this means that the graph of your max_memory option compared to the actual buffer size that results will look like a set of stairs rather than a smooth line. You can see this behavior by looking at the output of dm_xe_sessions, specifically the fields related to the buffer sizes, over a range of different memory inputs: Note: This test was run on a 2 core machine using per_cpu partitioning which results in 5 buffers. (Seem my previous post referenced above for the math behind buffer count.) input_memory_kb total_regular_buffers regular_buffer_size total_buffer_size 637 5 130867 654335 638 5 130867 654335 639 5 130867 654335 640 5 196403 982015 641 5 196403 982015 642 5 196403 982015 This is just a segment of the results that shows one of the “jumps” between the buffer boundary at 639 KB and 640 KB. You can verify the size boundary by doing the math on the regular_buffer_size field, which is returned in bytes: 196403 – 130867 = 65536 bytes 65536 / 1024 = 64 KB The relationship between the input for max_memory and when the regular_buffer_size is going to jump from one 64K boundary to the next is going to change based on the number of buffers being created. The number of buffers is dependent on the partition mode you choose. If you choose any partition mode other than NONE, the number of buffers will depend on your hardware configuration. (Again, see the earlier post referenced above.) With the default partition mode of none, you always get three buffers, regardless of machine configuration, so I generated a “range table” for max_memory settings between 1 KB and 4096 KB as an example. start_memory_range_kb end_memory_range_kb total_regular_buffers regular_buffer_size total_buffer_size 1 191 NULL NULL NULL 192 383 3 130867 392601 384 575 3 196403 589209 576 767 3 261939 785817 768 959 3 327475 982425 960 1151 3 393011 1179033 1152 1343 3 458547 1375641 1344 1535 3 524083 1572249 1536 1727 3 589619 1768857 1728 1919 3 655155 1965465 1920 2111 3 720691 2162073 2112 2303 3 786227 2358681 2304 2495 3 851763 2555289 2496 2687 3 917299 2751897 2688 2879 3 982835 2948505 2880 3071 3 1048371 3145113 3072 3263 3 1113907 3341721 3264 3455 3 1179443 3538329 3456 3647 3 1244979 3734937 3648 3839 3 1310515 3931545 3840 4031 3 1376051 4128153 4032 4096 3 1441587 4324761 As you can see, there are 21 “steps” within this range and max_memory values below 192 KB fall below the 64K per buffer limit so they generate an error when you attempt to specify them. Max approximates True as memory approaches 64K The upshot of this is that the max_memory option does not imply a contract for the maximum memory that will be used for the session buffers (Those of you who read Take it to the Max (and beyond) know that max_memory is really only referring to the event session buffer memory.) but is more of an estimate of total buffer size to the nearest higher multiple of 64K times the number of buffers you have. The maximum delta between your initial max_memory setting and the true total buffer size occurs right after you break through a 64K boundary, for example if you set max_memory = 576 KB (see the green line in the table), your actual buffer size will be closer to 767 KB in a non-partitioned event session. You get “stepped up” for every 191 KB block of initial max_memory which isn’t likely to cause a problem for most machines. Things get more interesting when you consider a partitioned event session on a computer that has a large number of logical CPUs or NUMA nodes. Since each buffer gets “stepped up” when you break a boundary, the delta can get much larger because it’s multiplied by the number of buffers. For example, a machine with 64 logical CPUs will have 160 buffers using per_cpu partitioning or if you have 8 NUMA nodes configured on that machine you would have 24 buffers when using per_node. If you’ve just broken through a 64K boundary and get “stepped up” to the next buffer size you’ll end up with total buffer size approximately 10240 KB and 1536 KB respectively (64K * # of buffers) larger than max_memory value you might think you’re getting. Using per_cpu partitioning on large machine has the most impact because of the large number of buffers created. If the amount of memory being used by your system within these ranges is important to you then this is something worth paying attention to and considering when you configure your event sessions. The DMV dm_xe_sessions is the tool to use to identify the exact buffer size for your sessions. In addition to the regular buffers (read: event session buffers) you’ll also see the details for large buffers if you have configured MAX_EVENT_SIZE. The “buffer steps” for any given hardware configuration should be static within each partition mode so if you want to have a handy reference available when you configure your event sessions you can use the following code to generate a range table similar to the one above that is applicable for your specific machine and chosen partition mode. DECLARE @buf_size_output table (input_memory_kb bigint, total_regular_buffers bigint, regular_buffer_size bigint, total_buffer_size bigint) DECLARE @buf_size int, @part_mode varchar(8) SET @buf_size = 1 -- Set to the begining of your max_memory range (KB) SET @part_mode = 'per_cpu' -- Set to the partition mode for the table you want to generate WHILE @buf_size <= 4096 -- Set to the end of your max_memory range (KB) BEGIN     BEGIN TRY         IF EXISTS (SELECT * from sys.server_event_sessions WHERE name = 'buffer_size_test')             DROP EVENT SESSION buffer_size_test ON SERVER         DECLARE @session nvarchar(max)         SET @session = 'create event session buffer_size_test on server                         add event sql_statement_completed                         add target ring_buffer                         with (max_memory = ' + CAST(@buf_size as nvarchar(4)) + ' KB, memory_partition_mode = ' + @part_mode + ')'         EXEC sp_executesql @session         SET @session = 'alter event session buffer_size_test on server                         state = start'         EXEC sp_executesql @session         INSERT @buf_size_output (input_memory_kb, total_regular_buffers, regular_buffer_size, total_buffer_size)             SELECT @buf_size, total_regular_buffers, regular_buffer_size, total_buffer_size FROM sys.dm_xe_sessions WHERE name = 'buffer_size_test'     END TRY     BEGIN CATCH         INSERT @buf_size_output (input_memory_kb)             SELECT @buf_size     END CATCH     SET @buf_size = @buf_size + 1 END DROP EVENT SESSION buffer_size_test ON SERVER SELECT MIN(input_memory_kb) start_memory_range_kb, MAX(input_memory_kb) end_memory_range_kb, total_regular_buffers, regular_buffer_size, total_buffer_size from @buf_size_output group by total_regular_buffers, regular_buffer_size, total_buffer_size Thanks to Jonathan for an interesting question and a chance to explore some of the details of Extended Event internals. - Mike

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• ODI 12c - Parallel Table Load

  - by David Allan

  In this post we will look at the ODI 12c capability of parallel table load from the aspect of the mapping developer and the knowledge module developer - two quite different viewpoints. This is about parallel table loading which isn't to be confused with loading multiple targets per se. It supports the ability for ODI mappings to be executed concurrently especially if there is an overlap of the datastores that they access, so any temporary resources created may be uniquely constructed by ODI. Temporary objects can be anything basically - common examples are staging tables, indexes, views, directories - anything in the ETL to help the data integration flow do its job. In ODI 11g users found a few workarounds (such as changing the technology prefixes - see here) to build unique temporary names but it was more of a challenge in error cases. ODI 12c mappings by default operate exactly as they did in ODI 11g with respect to these temporary names (this is also true for upgraded interfaces and scenarios) but can be configured to support the uniqueness capabilities. We will look at this feature from two aspects; that of a mapping developer and that of a developer (of procedures or KMs). 1. Firstly as a Mapping Developer..... 1.1 Control when uniqueness is enabled A new property is available to set unique name generation on/off. When unique names have been enabled for a mapping, all temporary names used by the collection and integration objects will be generated using unique names. This property is presented as a check-box in the Property Inspector for a deployment specification. 1.2 Handle cleanup after successful execution Provided that all temporary objects that are created have a corresponding drop statement then all of the temporary objects should be removed during a successful execution. This should be the case with the KMs developed by Oracle. 1.3 Handle cleanup after unsuccessful execution If an execution failed in ODI 11g then temporary tables would have been left around and cleaned up in the subsequent run. In ODI 12c, KM tasks can now have a cleanup-type task which is executed even after a failure in the main tasks. These cleanup tasks will be executed even on failure if the property 'Remove Temporary Objects on Error' is set. If the agent was to crash and not be able to execute this task, then there is an ODI tool (OdiRemoveTemporaryObjects here) you can invoke to cleanup the tables - it supports date ranges and the like. That's all there is to it from the aspect of the mapping developer it's much, much simpler and straightforward. You can now execute the same mapping concurrently or execute many mappings using the same resource concurrently without worrying about conflict.  2. Secondly as a Procedure or KM Developer..... In the ODI Operator the executed code shows the actual name that is generated - you can also see the runtime code prior to execution (introduced in 11.1.1.7), for example below in the code type I selected 'Pre-executed Code' this lets you see the code about to be processed and you can also see the executed code (which is the default view). References to the collection (C$) and integration (I$) names will be automatically made unique by using the odiRef APIs - these objects will have unique names whenever concurrency has been enabled for a particular mapping deployment specification. It's also possible to use name uniqueness functions in procedures and your own KMs. 2.1 New uniqueness tags  You can also make your own temporary objects have unique names by explicitly including either %UNIQUE_STEP_TAG or %UNIQUE_SESSION_TAG in the name passed to calls to the odiRef APIs. Such names would always include the unique tag regardless of the concurrency setting. To illustrate, let's look at the getObjectName() method. At <% expansion time, this API will append %UNIQUE_STEP_TAG to the object name for collection and integration tables. The name parameter passed to this API may contain  %UNIQUE_STEP_TAG or %UNIQUE_SESSION_TAG. This API always generates to the <? version of getObjectName() At execution time this API will replace the unique tag macros with a string that is unique to the current execution scope. The returned name will conform to the name-length restriction for the target technology, and its pattern for the unique tag. Any necessary truncation will be performed against the initial name for the object and any other fixed text that may have been specified. Examples are:- <?=odiRef.getObjectName("L", "%COL_PRFEMP%UNIQUE_STEP_TAG", "D")?> SCOTT.C$_EABH7QI1BR1EQI3M76PG9SIMBQQ <?=odiRef.getObjectName("L", "EMP%UNIQUE_STEP_TAG_AE", "D")?> SCOTT.EMPAO96Q2JEKO0FTHQP77TMSAIOSR_ Methods which have this kind of support include getFrom, getTableName, getTable, getObjectShortName and getTemporaryIndex. There are APIs for retrieving this tag info also, the getInfo API has been extended with the following properties (the UNIQUE* properties can also be used in ODI procedures); UNIQUE_STEP_TAG - Returns the unique value for the current step scope, e.g. 5rvmd8hOIy7OU2o1FhsF61 Note that this will be a different value for each loop-iteration when the step is in a loop. UNIQUE_SESSION_TAG - Returns the unique value for the current session scope, e.g. 6N38vXLrgjwUwT5MseHHY9 IS_CONCURRENT - Returns info about the current mapping, will return 0 or 1 (only in % phase) GUID_SRC_SET - Returns the UUID for the current source set/execution unit (only in % phase) The getPop API has been extended with the IS_CONCURRENT property which returns info about an mapping, will return 0 or 1.  2.2 Additional APIs Some new APIs are provided including getFormattedName which will allow KM developers to construct a name from fixed-text or ODI symbols that can be optionally truncate to a max length and use a specific encoding for the unique tag. It has syntax getFormattedName(String pName[, String pTechnologyCode]) This API is available at both the % and the ? phase.  The format string can contain the ODI prefixes that are available for getObjectName(), e.g. %INT_PRF, %COL_PRF, %ERR_PRF, %IDX_PRF alongwith %UNIQUE_STEP_TAG or %UNIQUE_SESSION_TAG. The latter tags will be expanded into a unique string according to the specified technology. Calls to this API within the same execution context are guaranteed to return the same unique name provided that the same parameters are passed to the call. e.g. <%=odiRef.getFormattedName("%COL_PRFMY_TABLE%UNIQUE_STEP_TAG_AE", "ORACLE")%> <?=odiRef.getFormattedName("%COL_PRFMY_TABLE%UNIQUE_STEP_TAG_AE", "ORACLE")?> C$_MY_TAB7wDiBe80vBog1auacS1xB_AE <?=odiRef.getFormattedName("%COL_PRFMY_TABLE%UNIQUE_STEP_TAG.log", "FILE")?> C2_MY_TAB7wDiBe80vBog1auacS1xB.log 2.3 Name length generation  As part of name generation, the length of the generated name will be compared with the maximum length for the target technology and truncation may need to be applied. When a unique tag is included in the generated string it is important that uniqueness is not compromised by truncation of the unique tag. When a unique tag is NOT part of the generated name, the name will be truncated by removing characters from the end - this is the existing 11g algorithm. When a unique tag is included, the algorithm will first truncate the <postfix> and if necessary  the <prefix>. It is recommended that users will ensure there is sufficient uniqueness in the <prefix> section to ensure uniqueness of the final resultant name. SUMMARY To summarize, ODI 12c make it much simpler to utilize mappings in concurrent cases and provides APIs for helping developing any procedures or custom knowledge modules in such a way they can be used in highly concurrent, parallel scenarios. 

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• Monitor your Hard Drive’s Health with Acronis Drive Monitor

  - by Matthew Guay

  Are you worried that your computer’s hard drive could die without any warning?  Here’s how you can keep tabs on it and get the first warning signs of potential problems before you actually lose your critical data. Hard drive failures are one of the most common ways people lose important data from their computers.  As more of our memories and important documents are stored digitally, a hard drive failure can mean the loss of years of work.  Acronis Drive Monitor helps you avert these disasters by warning you at the first signs your hard drive may be having trouble.  It monitors many indicators, including heat, read/write errors, total lifespan, and more. It then notifies you via a taskbar popup or email that problems have been detected.  This early warning lets you know ahead of time that you may need to purchase a new hard drive and migrate your data before it’s too late. Getting Started Head over to the Acronis site to download Drive Monitor (link below).  You’ll need to enter your name and email, and then you can download this free tool. Also, note that the download page may ask if you want to include a trial of their for-pay backup program.  If you wish to simply install the Drive Monitor utility, click Continue without adding. Run the installer when the download is finished.  Follow the prompts and install as normal. Once it’s installed, you can quickly get an overview of your hard drives’ health.  Note that it shows 3 categories: Disk problems, Acronis backup, and Critical Events.  On our computer, we had Seagate DiskWizard, an image backup utility based on Acronis Backup, installed, and Acronis detected it. Drive Monitor stays running in your tray even when the application window is closed.  It will keep monitoring your hard drives, and will alert you if there’s a problem. Find Detailed Information About Your Hard Drives Acronis’ simple interface lets you quickly see an overview of how the drives on your computer are performing.  If you’d like more information, click the link under the description.  Here we see that one of our drives have overheated, so click Show disks to get more information. Now you can select each of your drives and see more information about them.  From the Disk overview tab that opens by default, we see that our drive is being monitored, has been running for a total of 368 days, and that it’s health is good.  However, it is running at 113F, which is over the recommended max of 107F.   The S.M.A.R.T. parameters tab gives us more detailed information about our drive.  Most users wouldn’t know what an accepted value would be, so it also shows the status.  If the value is within the accepted parameters, it will report OK; otherwise, it will show that has a problem in this area. One very interesting piece of information we can see is the total number of Power-On Hours, Start/Stop Count, and Power Cycle Count.  These could be useful indicators to check if you’re considering purchasing a second hand computer.  Simply load this program, and you’ll get a better view of how long it’s been in use. Finally, the Events tab shows each time the program gave a warning.  We can see that our drive, which had been acting flaky already, is routinely overheating even when our other hard drive was running in normal temperature ranges. Monitor Acronis Backups And Critical Errors In addition to monitoring critical stats of your hard drives, Acronis Drive Monitor also keeps up with the status of your backup software and critical events reported by Windows.  You can access these from the front page, or via the links on the left hand sidebar.  If you have any edition of any Acronis Backup product installed, it will show that it was detected.  Note that it can only monitor the backup status of the newest versions of Acronis Backup and True Image. If no Acronis backup software was installed, it will show a warning that the drive may be unprotected and will give you a link to download Acronis backup software.   If you have another backup utility installed that you wish to monitor yourself, click Configure backup monitoring, and then disable monitoring on the drives you’re monitoring yourself. Finally, you can view any detected Critical events from the Critical events tab on the left. Get Emailed When There’s a Problem One of Drive Monitor’s best features is the ability to send you an email whenever there’s a problem.  Since this program can run on any version of Windows, including the Server and Home Server editions, you can use this feature to stay on top of your hard drives’ health even when you’re not nearby.  To set this up, click Options in the top left corner. Select Alerts on the left, and then click the Change settings link to setup your email account. Enter the email address which you wish to receive alerts, and a name for the program.  Then, enter the outgoing mail server settings for your email.  If you have a Gmail account, enter the following information: Outgoing mail server (SMTP): smtp.gmail.com Port: 587 Username and Password: Your gmail address and password Check the Use encryption box, and then select TLS from the encryption options.   It will now send a test message to your email account, so check and make sure it sent ok. Now you can choose to have the program automatically email you when warnings and critical alerts appear, and also to have it send regular disk status reports.   Conclusion Whether you’ve got a brand new hard drive or one that’s seen better days, knowing the real health of your it is one of the best ways to be prepared before disaster strikes.  It’s no substitute for regular backups, but can help you avert problems.  Acronis Drive Monitor is a nice tool for this, and although we wish it wasn’t so centered around their backup offerings, we still found it a nice tool. Link Download Acronis Drive Monitor (registration required) Similar Articles Productive Geek Tips Quick Tip: Change Monitor Timeout From Command LineAnalyze and Manage Hard Drive Space with WinDirStatMonitor CPU, Memory, and Disk IO In Windows 7 with Taskbar MetersDefrag Multiple Hard Drives At Once In WindowsFind Your Missing USB Drive on Windows XP TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips HippoRemote Pro 2.2 Xobni Plus for Outlook All My Movies 5.9 CloudBerry Online Backup 1.5 for Windows Home Server Windows 7’s WordPad is Actually Good Greate Image Viewing and Management with Zoner Photo Studio Free Windows Media Player Plus! – Cool WMP Enhancer Get Your Team’s World Cup Schedule In Google Calendar Backup Drivers With Driver Magician TubeSort: YouTube Playlist Organizer

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• WWDC and Tech Ed: A Tale of Two DevCons

  - by andrewbrust

  Next week marks the first full week of June.  Summer will feel in full swing and it will be a pretty big season for technology.  In seeming acknowledgement of that very fact, both Apple and Microsoft will be holding large developers conferences starting Monday.  Apple will hold its annual Worldwide Developers Conference (WWDC) in lovely San Francisco and Microsoft will hold its Tech Ed conference in muggy, oil-laden yet soulful New Orleans.  A brief survey of each show reveals much about the differences in each company’s offerings, strategy, and approach to customers and partners. In the interest of full disclosure, I must explain that I will be speaking at Microsoft’s Tech Ed show, and have done so, on and off, since 2003.  I have never been to an Apple conference and, as readers of this blog may know, I acquired my first ever Apple product 2 months ago when I bought an iPad on the day of that product’s launch.  I think I have keen insights into Microsoft’s conference.  My ability to comment on Apple’s event ranges somewhere between backseat driver and naive observer.  Just so you know. Although both shows cater to their respective company’s developers, there are a number of differences in the events’ purposes and content approaches.  First off, let’s consider each show as a news and PR vehicle.  WWDC will feature Steve Jobs’ keynote address and most likely will be where Apple officially reveals details of its 4th-generation iPhone. Jobs will likely also provide deep background information on the corresponding iPhone OS release.  These presumed announcements will make the show a magnet for the tech press and tech blogger elite.  Apple’s customers will be interested too, especially since the iPhone OS release will likely be made available to owners of existing iPhone, iPod Touch and iPad devices. Tech Ed, on the other hand, may not be especially newsworthy at all.  The keynote address will be given by Bob Muglia, who is President of the company’s Server and Tools Division, and he’ll likely be reviewing things more than previewing them. That’s because the company has, in the last 6-8 months, already released new versions of a majority of its products, including Windows, Office, SharePoint, SQL Server, Exchange, its Azure cloud platform, its .NET software development layer, its Silverlight Rich Internet Application (RIA) technology and its Visual Studio developer suite.  Redmond’s product pipeline has functioned more like a firehose of late, and the company has a ton of work to do to get developers up to speed on everything that’s new. I know I keep saying “developers,” but in Tech Ed’s case, that’s not really accurate.  In North America, Tech Ed caters to both developers and IT pros (i.e. technologists who work with physical IT infrastructure, as well as security and administration of the server software that runs on it).  This pairing has, since its inception, struck some as anomalous and others, including many exhibitors, as very smart. Certainly, it means Tech Ed ends up being a confab for virtually all professionals in Microsoft’s ecosystem.  And this year, Microsoft’s Business Intelligence (BI) conference will be co-located with Tech Ed, further enhancing that fusion effect. Clearly then, Microsoft’s show will focus on education, as its name assures us.  Apple’s will serve as both a press event and an opportunity to get its own App Store developer channel synced up with its newest technology advances.  For example, we already know that iPhone OS 4.0 will provide for a limited multitasking capability; that will only work well if people know how to code to it in a capable way.  Apple also told us its iAd advertising platform will be part of the new OS, and Steve Jobs insists that’s to provide a revenue opportunity for developers.  This too, then, needs to be explicated and soaked up buy the faithful. A look at each show’s breakout session lineup provides some interesting takeaways.  WWDC will have very few Mac-specific sessions on offer, and virtually no sessions that at are IT- or “Enterprise-“ related.  It’s all about the phone, music players and tablets.  However, WWDC will have plenty of low-level, hardcore tech coverage of such things as Advanced Memory Analysis and Creating Secure Applications, as well as lots of rich media-related content like Core Animation and Game Design and Development.  Beyond Apple’s proprietary platform, WWDC will also feature an array of sessions on HTML 5 and other Web standards.  In all, WWDC offers over 100 technical sessions and hands-on labs. What about Tech Ed’s editorial content?  Like the target audience, it really runs the gamut.  The show has 21 tracks (versus WWDC’s 5) and more than 745 “learning opportunities” which include breakout sessions, demo stations, hands-on labs and BIrds of a Feather discussion sessions.  Topics range from Architecture talks like Patterns of Parallel Programming to cloud computing talks like Building High Capacity Compute Applications with Windows Azure to IT-focused topics like Virtualization of Microsoft SharePoint 2010 Farm Architecture.  I also count 19 sessions on Windows Phone 7.  Unfortunately, with regard to Web standards and HTML 5, only a few sessions are offered, all of them specific to Internet Explorer. All-in-all, Apple’s show looks more exciting and “sexier” than Tech Ed. Microsoft’s show seems a lot more enterprise-focused than WWDC. This is, of course, well in sync with each company’s approach and products.  Microsoft’s content is much wider ranging and bests WWDC in sheer volume of sessions and labs.  I suppose some might argue that less is more; others that Apple’s consumer-focused offerings simply don’t provide for the same depth of coverage to a business audience.  Microsoft has a serious focus on the cloud and  a paucity of coverage on client-side Web standards; Apple has virtually no cloud offering at all.  Again, this reflects each tech titan’s go-to-market strategy. My own take is that employees of each company should attend the other’s event.  The amount of mutual exclusivity in content may make sense in terms of corporate philosophy, but the reality is that each company could stand to diversify into the other’s territory, at least somewhat. My own talk at Tech Ed will focus on competitive analysis around Microsoft’s BI products.  Apple does not today figure into that analysis. Maybe one day it will.

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• Robotic Arm &ndash; Hardware

  - by Szymon Kobalczyk

  This is first in series of articles about project I've been building  in my spare time since last Summer. Actually it all began when I was researching a topic of modeling human motion kinematics in order to create gesture recognition library for Kinect. This ties heavily into motion theory of robotic manipulators so I also glanced at some designs of robotic arms. Somehow I stumbled upon this cool looking open source robotic arm: It was featured on Thingiverse and published by user jjshortcut (Jan-Jaap). Since for some time I got hooked on toying with microcontrollers, robots and other electronics, I decided to give it a try and build it myself. In this post I will describe the hardware build of the arm and in later posts I will be writing about the software to control it. Another reason to build the arm myself was the cost factor. Even small commercial robotic arms are quite expensive – products from Lynxmotion and Dagu look great but both cost around USD $300 (actually there is one cheap arm available but it looks more like a toy to me). In comparison this design is quite cheap. It uses seven hobby grade servos and even the cheapest ones should work fine. The structure is build from a set of laser cut parts connected with few metal spacers (15mm and 47mm) and lots of M3 screws. Other than that you’d only need a microcontroller board to drive the servos. So in total it comes a lot cheaper to build it yourself than buy an of the shelf robotic arm. Oh, and if you don’t like this one there are few more robotic arm projects at Thingiverse (including one by oomlout). Laser cut parts Some time ago I’ve build another robot using laser cut parts so I knew the process already. You can grab the design files in both DXF and EPS format from Thingiverse, and there are also 3D models of each part in STL. Actually the design is split into a second project for the mini servo gripper (there is also a standard servo version available but it won’t fit this arm).  I wanted to make some small adjustments, layout, and add measurements to the parts before sending it for cutting. I’ve looked at some free 2D CAD programs, and finally did all this work using QCad 3 Beta with worked great for me (I also tried LibreCAD but it didn’t work that well). All parts are cut from 4 mm thick material. Because I was worried that acrylic is too fragile and might break, I also ordered another set cut from plywood. In the end I build it from plywood because it was easier to glue (I was told acrylic requires a special glue). Btw. I found a great laser cutter service in Kraków and highly recommend it (www.ebbox.com.pl). It cost me only USD $26 for both sets ($16 acrylic + $10 plywood). Metal parts I bought all the M3 screws and nuts at local hardware store. Make sure to look for nylon lock (nyloc) nuts for the gripper because otherwise it unscrews and comes apart quickly. I couldn’t find local store with metal spacers and had to order them online (you’d need 11 x 47mm and 3 x 15mm). I think I paid less than USD $10 for all metal parts. Servos This arm uses five standards size servos to drive the arm itself, and two micro servos are used on the gripper. Author of the project used Modelcraft RS-2 Servo and Modelcraft ES-05 HT Servo. I had two Futaba S3001 servos laying around, and ordered additional TowerPro SG-5010 standard size servos and TowerPro SG90 micro servos. However it turned out that the SG90 won’t fit in the gripper so I had to replace it with a slightly smaller E-Sky EK2-0508 micro servo. Later it also turned out that Futaba servos make some strange noise while working so I swapped one with TowerPro SG-5010 which has higher torque (8kg / cm). I’ve also bought three servo extension cables. All servos cost me USD $45. Assembly The build process is not difficult but you need to think carefully about order of assembling it. You can do the base and upper arm first. Because two servos in the base are close together you need to put first with one piece of lower arm already connected before you put the second servo. Then you connect the upper arm and finally put the second piece of lower arm to hold it together. Gripper and base require some gluing so think it through too. Make sure to look closely at all the photos on Thingiverse (also other people copies) and read additional posts on jjshortcust’s blog: My mini servo grippers and completed robotic arm  Multiply the robotic arm and electronics Here is also Rob’s copy cut from aluminum My assembled arm looks like this – I think it turned out really nice: Servo controller board The last piece of hardware I needed was an electronic board that would take command from PC and drive all seven servos. I could probably use Arduino for this task, and in fact there are several Arduino servo shields available (for example from Adafruit or Renbotics).  However one problem is that most support only up to six servos, and second that their accuracy is limited by Arduino’s timer frequency. So instead I looked for dedicated servo controller and found a series of Maestro boards from Pololu. I picked the Pololu Mini Maestro 12-Channel USB Servo Controller. It has many nice features including native USB connection, high resolution pulses (0.25µs) with no jitter, built-in speed and acceleration control, and even scripting capability. Another cool feature is that besides servo control, each channel can be configured as either general input or output. So far I’m using seven channels so I still have five available to connect some sensors (for example distance sensor mounted on gripper might be useful). And last but important factor was that they have SDK in .NET – what more I could wish for! The board itself is very small – half of the size of Tic-Tac box. I picked one for about USD $35 in this store. Perhaps another good alternative would be the Phidgets Advanced Servo 8-Motor – but it is significantly more expensive at USD $87.30. The Maestro Controller Driver and Software package includes Maestro Control Center program with lets you immediately configure the board. For each servo I first figured out their move range and set the min/max limits. I played with setting the speed an acceleration values as well. Big issue for me was that there are two servos that control position of lower arm (shoulder joint), and both have to be moved at the same time. This is where the scripting feature of Pololu board turned out very helpful. I wrote a script that synchronizes position of second servo with first one – so now I only need to move one servo and other will follow automatically. This turned out tricky because I couldn’t find simple offset mapping of the move range for each servo – I had to divide it into several sub-ranges and map each individually. The scripting language is bit assembler-like but gets the job done. And there is even a runtime debugging and stack view available. Altogether I’m very happy with the Pololu Mini Maestro Servo Controller, and with this final piece I completed the build and was able to move my arm from the Meastro Control program.   The total cost of my robotic arm was: $10 laser cut parts $10 metal parts $45 servos $35 servo controller ----------------------- $100 total So here you have all the information about the hardware. In next post I’ll start talking about the software that I wrote in Microsoft Robotics Developer Studio 4. Stay tuned!

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