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• Does Dart have any useful features for web programmers?

  - by marko

  http://www.dartlang.org/ I've checked out the site very briefly, and got curious. Is there any advantages of using Dart? Is it just a replacement for JavaScript? It looks like simpler Java. Writing quite a lot of C# at work, the language feels very much like what I'm used to, so learning the syntax looks like a breeze to learn. Has anybody any opinions or experiences with the language? (Compared to CoffeeScript (= I'm not doing Ruby syntax) the syntax looks more familiar to me).

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• Does the optimizer filter subqueries with outer where clauses

  - by Mongus Pong

  Take the following query: select * from ( select a, b from c UNION select a, b from d ) where a = 'mung' Will the optimizer generally work out that I am filtering a on the value 'mung' and consequently filter mung on each of the queries in the subquery. OR will it run each query within the subquery union and return the results to the outer query for filtering (as the query would perhaps suggest) In which case the following query would perform better : select * from ( select a, b from c where a = 'mung' UNION select a, b from d where a = 'mung' ) Obviously query 1 is best for maintenance, but is it sacrificing much performace for this? Which is best?

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• Class as first-class object

  - by mrpyo

  Could a class be a first-class object? If yes, how would the implementation look? I mean, how could syntax for dynamically creating new classes look like? EDIT: I mean what example syntax could look like (I'm sorry, English is not my native language), but still I believe this question makes sense - how you give this functionality while keeping language consistent. For example how you create reference for new type. Do you make reference first-class object too and then use something like this: Reference<newType> r = new Reference<newType>(); r.set(value); Well this could get messy so you may just force user to use Object type references for dynamically created classes, but then you loose type-checking. I think creating concise syntax for this is interesting problem which solving could lead to better language design, maybe language which is metalanguage for itself (I wonder if this is possible).

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• postgreSQL - pg_class question

  - by Sachin Chourasiya

  PostgreSQL stores statistics about tables in the system table called pg_class. The query planner accesses this table for every query. These statistics may only be updated using the analyze command. If the analyze command is not run often, the statistics in this table may not be accurate and the query planner may make poor decisions which can degrade system performance. Another strategy is for the query planner to generate these statistics for each query (including selects, inserts, updates, and deletes). This approach would allow the query planner to have the most up-to-date statistics possible. Why postgres always rely on pg_class instead?

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• postgres SQL - pg_class question

  - by Sachin Chourasiya

  PostgreSQL stores statistics about tables in the system table called pg_class. The query planner accesses this table for every query. These statistics may only be updated using the analyze command. If the analyze command is not run often, the statistics in this table may not be accurate and the query planner may make poor decisions which can degrade system performance. Another strategy is for the query planner to generate these statistics for each query (including selects, inserts, updates, and deletes). This approach would allow the query planner to have the most up-to-date statistics possible. Why postgres always rely on pg_class instead?

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• Is this a valid benefit of using embedded SQL over stored procedures?

  - by George

  Here's an argument for SPs that I haven't heard. Flamers, be gentle with the down tick, Since there is overhead associated with each trip to the database server, I would suggest that a POSSIBLE reason for placing your SQL in SPs over embedded code is that you are more insulated to change without taking a performance hit. For example. Let's say you need to perform Query A that returns a scalar integer. Then, later, the requirements change and you decide that it the results of the scalar is x that then, and only then, you need to perform another query. If you performed the first query in a SP, you could easily check the result of the first query and conditionally execute the 2nd SQL in the same SP. How would you do this efficiently in embedded SQL w/o perform a separate query or an unnecessary query? Here's an example: --This SP may return 1 or two queries. SELECT @CustCount = COUNT(*) FROM CUSTOMER IF @CustCount 10 SELECT * FROM PRODUCT Can this/what is the best way to do this in embedded SQL?

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• getting sql records

  - by droidus

  when i run this code, it returns the topic fine... $query = mysql_query("SELECT topic FROM question WHERE id = '$id'"); if(mysql_num_rows($query) > 0) { $row = mysql_fetch_array($query) or die(mysql_error()); $topic = $row['topic']; } but when I change it to this, it doesn't run at all. why is this happening? $query = mysql_query("SELECT topic, lock FROM question WHERE id = '$id'"); if(mysql_num_rows($query) > 0) { $row = mysql_fetch_array($query) or die(mysql_error()); $topic = $row['topic']; $lockedThread = $row['lock']; echo "here: " . $lockedThread; }

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• Insert using strored procedure from nhibernate

  - by jcreddy

  Hi I am using the following code snippets to insert values using stored procedure. the code is executing successfully but no record is inserted in DB. Please suggest with simple example. **---- stored procedure--------** Create PROCEDURE [dbo].[SampleInsert] @id int, @name varchar(50) AS BEGIN insert into test (id, name) values (@id, @name); END **------.hbm file-------** <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"> <sql-query name="Procedure"> exec SampleInsert :Id,:Name </sql-query> </hibernate-mapping> **--------c# code to insert value using above sp------** ISessionFactory sessionFactory = new Configuration().Configure().BuildSessionFactory(); ISession session = sessionFactory.OpenSession(); IQuery query = session.GetNamedQuery("Procedure"); query.SetParameter("Id", "222"); query.SetParameter("Name", "testsp"); query.SetResultTransformer(new NHibernate.Transform.AliasToBeanConstructorResultTransformer(typeof(Procedure).GetConstructors()[0])); Regards Jcreddy

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• pagination in php error

  - by fusion

  i've implemented this pagination class for my webpage in a separate file called class.pagination.php, but when i execute the page, nothing happens. it just displays a blank page. this is my search.php file, where i'm calling this class: <?php include 'config.php'; require ('class.pagination.php'); $search_result = ""; $search_result = $_GET["q"]; $search_result = trim($search_result); //Check if the string is empty if ($search_result == "") { echo "<p class='error'>Search Error. Please Enter Your Search Query.</p>" ; exit(); } //search query for multiple keywords if(!empty($search_result)) { // the table to search $table = "thquotes"; // explode search words into an array $arraySearch = explode(" ", $search_result); // table fields to search $arrayFields = array(0 => "cQuotes"); $countSearch = count($arraySearch); $a = 0; $b = 0; $query = "SELECT cQuotes, vAuthor, cArabic, vReference FROM ".$table." WHERE ("; $countFields = count($arrayFields); while ($a < $countFields) { while ($b < $countSearch) { $query = $query."$arrayFields[$a] LIKE '%$arraySearch[$b]%'"; $b++; if ($b < $countSearch) { $query = $query." AND "; } } $b = 0; $a++; if ($a < $countFields) { $query = $query.") OR ("; } } $query = $query.")"; $result = mysql_query($query, $conn) or die ('Error: '.mysql_error()); $totalrows = mysql_num_rows($result); if($totalrows < 1) { echo '<span class="error2">No matches found for "'.$search_result.'"</span>'; } else { ?> <div class="caption">Search Results</div> <div class="center_div"> <table> <?php while ($row= mysql_fetch_array($result, MYSQL_ASSOC)) { $cQuote = highlightWords(htmlspecialchars($row['cQuotes']), $search_result); ?> <tr> <td style="text-align:right; font-size:15px;"><?php h($row['cArabic']); ?></td> <td style="font-size:16px;"><?php echo $cQuote; ?></td> <td style="font-size:12px;"><?php h($row['vAuthor']); ?></td> <td style="font-size:12px; font-style:italic; text-align:right;"><?php h($row['vReference']); ?></td> </tr> <?php } ?> </table> </div> <?php } } else { exit(); } //Setting Pagination $pagination = new pagination(); $pagination->byPage = 5; $pagination->rows = $totalrows; // number of records in a table-back mysql_num_rows () instance or another, you have to play $from = $pagination->fromPagination(); // sql used for applications such LIMIT $ from, $ pagination-> byPage $pages = $pagination->pages(); if(isset($pages)) {?> <div class="pagination"> <?foreach ($pages as $key){?> <?if($key['current'] == 1) {?> <a href="?p=<?=$key['p']?>" class="active"><?=$key['page']?></a> <?} else {?> <a href="?p=<?=$key['p']?>" class="inactive"><?=$key['page']?></a> <?}?> <?}?> </div> <?} //End Pagination ?>

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• output all data from db to a php page

  - by Sarit

  Hi, I'm a real beginner with PHP & mysql. Just for studying and for a simple example at school I would like to work this simple query and possibly output all the rows (or maybe even one) to a very basic output on a php page: <?php $user= "root"; $host="localhost"; $password=""; $database = "PetCatalog"; $cxn = mysqli_connect($host,$user,$password,$database) or die ("couldn’t connect to server"); $query = "SELECT * FROM Pet"; $result = mysql_query($cxn,$query) or die ("Couldn’t execute query."); $row = mysqli_fetch_assoc($result); echo "$result"; ?> this is the error message i've been getting: Warning: mysql_query() expects parameter 1 to be string, object given in C:\xampplite\htdocs\myblog\query.php on line 18 Couldn’t execute query. What should I do? Thanks!

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• Can all code be represented as a series of Map / Filter / Reduce operations?

  - by Mongus Pong

  I have recently been refactoring large chunks of code and replacing them with Linq queries. Removing the language bias - Linq is essentially a set of Map / Filter and Reduce operations that operate on a sequence of data. This got me thinking, how far would I theoretically be able to take this. Would I be able to rewrite the whole code base into a series (or even a single) of Map / Filter and Reduce operations. Unfortunately I get paid to do useful stuff, so I haven't been able to experiment much further, but I can't think of any code structure that couldn't be re structured as such. Side effected code can be dealt with via monads.. Even output is essentially mapping memory addresses to screen addresses. Is there anything that couldn't be (theoretically) rewritten as a Linq query?

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• How to run a set of SQL queries from a file, in PHP?

  - by Harish Kurup

  I have some set of SQL queries which is in a file(i.e query.sql), and i want to run those queries in files using PHP, the code that i have wrote is not working, //database config's... $file_name="query.sql"; $query==file($file_name); $array_length=count($query); for($i=0;$i<$array_length;$i++) { $data .= $query[$i]; } echo $data; mysql_query($data); it echos the SQL Query from the file but throws an error at mysql_query() function...

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• nodejs, mongodb - How do I operate on data from multiple queries?

  - by Ryan

  Hi all, I'm new to JS in general, but I am trying to query some data from MongoDB. Basically, my first query retrieves information for the session with the specified session id. The second query does a simple geospacial query for documents with a location near the specified location. I'm using the mongodb-native javascript driver. All of these query methods return their results in callbacks, so they're non-blocking. This is the root of my troubles. What I'm needing to do is retrieve the results of the second query, and create an Array of sessionIds of all the returned documents. Then I'm going to pass those to a function later. But, I can't generate this array and use it anywhere outside the callback. Does anyone have any idea how to properly do this? http://dpaste.org/wXiE/

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• PHP looping through an array to fetch a value for each key from database (third normal form)

  - by zomboble

  I am building a system, mostly for consolidating learning but will be used in practice. I will try and verbally explain the part of the E-R diagram I am focusing on: Each cadet can have many uniformID's Each Uniform ID is a new entry in table uniform, so cadets (table) may look like: id | name | ... | uniformID 1 | Example | ... | 1,2,3 uniform table: id | notes | cadet 1 | Need new blahh | 1 2 | Some stuff needed | 1 3 | Whatever you like | 1 On second thought, looks like I wont need that third column in the db. I am trying to iterate through each id in uniformID, code: <?php $cadet = $_GET['id']; // set from URL $query = mysql_query("SELECT `uniformID` FROM `cadets` WHERE id = '$cadet' LIMIT 1") or die(mysql_error()); // get uniform needed as string // store it while ($row = mysql_fetch_array($query)) { $uniformArray = $row['uniformID']; } echo $uniformArray . " "; $exploded = explode(",", $uniformArray); // convert into an array // for each key in the array perform a new query foreach ($exploded as $key => $value) { $query(count($exploded)); $query[$key] = mysql_query("SELECT * FROM `uniform` WHERE `id` = '$value'"); } ? As I say, this is mainly for consolidation purposes but I have come up with a error, sql is saying: Fatal error: Function name must be a string in C:\wamp\www\intranet\uniform.php on line 82 line 82 is: $query[$key] = mysql_query("SELECT * FROM `uniform` WHERE `id` = '$value'"); I wasn't sure it would work so I tried it and now i'm stuck! EDIT: Thanks to everyone who has contributed to this! This is now the working code: foreach ($exploded as $key => $value) { //$query(count($exploded)); $query = mysql_query("SELECT * FROM `uniform` WHERE `id` = '$value'"); while ($row = mysql_fetch_array($query)) { echo "<tr> <td>" . $row['id'] . "</td> <td>" . $row['note'] . "</td> </tr>"; } } Added the while and did the iteration by nesting it in the foreach

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• Insert using stored procedure from nhibernate

  - by jcreddy

  Hi I am using the following code snippets to insert values using stored procedure. the code is executing successfully but no record is inserted in DB. Please suggest with simple example. **---- stored procedure--------** Create PROCEDURE [dbo].[SampleInsert] @id int, @name varchar(50) AS BEGIN insert into test (id, name) values (@id, @name); END **------.hbm file-------** <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"> <sql-query name="Procedure"> exec SampleInsert :Id,:Name </sql-query> </hibernate-mapping> **--------c# code to insert value using above sp------** ISessionFactory sessionFactory = new Configuration().Configure().BuildSessionFactory(); ISession session = sessionFactory.OpenSession(); IQuery query = session.GetNamedQuery("Procedure"); query.SetParameter("Id", "222"); query.SetParameter("Name", "testsp"); query.SetResultTransformer(new NHibernate.Transform.AliasToBeanConstructorResultTransformer(typeof(Procedure).GetConstructors()[0])); Regards Jcreddy

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• Using cachedwithin attibute inside cfquery

  - by Jason

  When you use the cachedwithin attribute in a cfquery how does it store the query in memory. Does it store it by only the name you assign to the query? For example, if on my index page I cache a query for an hour and name it getPeople will a query with the same name on a different page (or the same page for that matter) use the cached results or does it use some better logic to decide if it is the same query? Also, if there is a variable in your query does the cache take into account the value of the variable?

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• Has Dart something useful that javascript doesn't have?

  - by marko

  http://www.dartlang.org/ I've checked out the site very briefly, and got curious. Is there any advantages of using Dart? Is it just a replacement for javascript? It looks like simpler java. Writing quite a lot of C# at work, the language feels very much like what I'm used to, so learning the syntax looks like a breeze to learn. Has anybody any opinions or experiences with the language? (Compared to coffeescript (= I'm not doing ruby syntax) the syntax looks more familiar to me).

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• Beginner's Question about accessing mysql using OOP

  - by user345690

  I am reading the PHP and mySQL web development book and so far been doing all the PHP and mysql using procedural. But then it talks about accessing mysql with objects. This works for me: //I define $db so can connect $query="select * FROM testing"; $result=mysqli_query($db,$query); while($row=mysqli_fetch_array($result)){ //echo the data } But when I try to do it with classes, it doesn't $query="select * FROM testing"; $result=$db->query($query); $row=$result->fetch_assoc(); Do I have to write my own class so it defines what query and fetch_assoc does? Or what?

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• converting ip to long string in mysql command !

  - by Mac Taylor

  hey guys I'm trying to use ip2country technique to show my users'flags simple thing to do is to write a sql statement and show users from session table and then query to see if their ip is in what range and show their flags it simple but dengerous becuase when showing 300 users online and fetching from session table and then query once again ip2country table to get the flags there will be surelly memory overusage problem now i wrote a query to make it in one query : SELECT s.session_ip,ipc.* FROM session s left join ip2country ipc ON ipc.ip_lo<=s.session_ip AND ipc.ip_hi>=s.session_ip WHERE s.session_time > '".( time() - 60) )."' now its clear above query is wrong cause ips saved in ip2country table is long string 1000013824 and ips saved in session table are real ip e.g. 193.169.0.0 now i know how to convert from ip to long in php ip2long() but is there any command in mysql to do it with out building another query !?

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• files get uploaded just before they get cancelled

  - by user1763986

  Got a little situation here where I am trying to cancel a file's upload. What I have done is stated that if the user clicks on the "Cancel" button, then it will simply remove the iframe so that it does not go to the page where it uploads the files into the server and inserts data into the database. Now this works fine if the user clicks on the "Cancel" button in quickish time the problem I have realised though is that if the user clicks on the "Cancel" button very late, it sometimes doesn't remove the iframe in time meaning that the file has just been uploaded just before the user has clicked on the "Cancel" button. So my question is that is there a way that if the file does somehow get uploaded before the user clicks on the "Cancel" button, that it deletes the data in the database and removes the file from the server? Below is the image upload form: <form action="imageupload.php" method="post" enctype="multipart/form-data" target="upload_target_image" onsubmit="return imageClickHandler(this);" class="imageuploadform" > <p class="imagef1_upload_process" align="center"> Loading...<br/> <img src="Images/loader.gif" /> </p> <p class="imagef1_upload_form" align="center"> <br/> <span class="imagemsg"></span> <label>Image File: <input name="fileImage" type="file" class="fileImage" /></label><br/> <br/> <label class="imagelbl"><input type="submit" name="submitImageBtn" class="sbtnimage" value="Upload" /></label> </p> <p class="imagef1_cancel" align="center"> <input type="reset" name="imageCancel" class="imageCancel" value="Cancel" /> </p> <iframe class="upload_target_image" name="upload_target_image" src="#" style="width:0px;height:0px;border:0px;solid;#fff;"></iframe> </form> Below is the jquery function which controls the "Cancel" button: $(imageuploadform).find(".imageCancel").on("click", function(event) { $('.upload_target_image').get(0).contentwindow $("iframe[name='upload_target_image']").attr("src", "javascript:'<html></html>'"); return stopImageUpload(2); }); Below is the php code where it uploads the files and inserts the data into the database. The form above posts to this php page "imageupload.php": <body> <?php include('connect.php'); session_start(); $result = 0; //uploads file move_uploaded_file($_FILES["fileImage"]["tmp_name"], "ImageFiles/" . $_FILES["fileImage"]["name"]); $result = 1; //set up the INSERT SQL query command to insert the name of the image file into the "Image" Table $imagesql = "INSERT INTO Image (ImageFile) VALUES (?)"; //prepare the above SQL statement if (!$insert = $mysqli->prepare($imagesql)) { // Handle errors with prepare operation here } //bind the parameters (these are the values that will be inserted) $insert->bind_param("s",$img); //Assign the variable of the name of the file uploaded $img = 'ImageFiles/'.$_FILES['fileImage']['name']; //execute INSERT query $insert->execute(); if ($insert->errno) { // Handle query error here } //close INSERT query $insert->close(); //Retrieve the ImageId of the last uploded file $lastID = $mysqli->insert_id; //Insert into Image_Question Table (be using last retrieved Image id in order to do this) $imagequestionsql = "INSERT INTO Image_Question (ImageId, SessionId, QuestionId) VALUES (?, ?, ?)"; //prepare the above SQL statement if (!$insertimagequestion = $mysqli->prepare($imagequestionsql)) { // Handle errors with prepare operation here echo "Prepare statement err imagequestion"; } //Retrieve the question number $qnum = (int)$_POST['numimage']; //bind the parameters (these are the values that will be inserted) $insertimagequestion->bind_param("isi",$lastID, 'Exam', $qnum); //execute INSERT query $insertimagequestion->execute(); if ($insertimagequestion->errno) { // Handle query error here } //close INSERT query $insertimagequestion->close(); ?> <!--Javascript which will output the message depending on the status of the upload (successful, failed or cancelled)--> <script> window.top.stopImageUpload(<?php echo $result; ?>, '<?php echo $_FILES['fileImage']['name'] ?>'); </script> </body> UPDATE: Below is the php code "cancelimage.php" where I want to delete the cancelled file from the server and delete the record from the database. It is set up but not finished, can somebody finish it off so I can retrieve the name of the file and it's id using $_SESSION? <?php // connect to the database include('connect.php'); /* check connection */ if (mysqli_connect_errno()) { printf("Connect failed: %s\n", mysqli_connect_error()); die(); } //remove file from server unlink("ImageFiles/...."); //need to retrieve file name here where the ... line is //DELETE query statement where it will delete cancelled file from both Image and Image Question Table $imagedeletesql = " DELETE img, img_q FROM Image AS img LEFT JOIN Image_Question AS img_q ON img_q.ImageId = img.ImageId WHERE img.ImageFile = ?"; //prepare delete query if (!$delete = $mysqli->prepare($imagedeletesql)) { // Handle errors with prepare operation here } //Dont pass data directly to bind_param store it in a variable $delete->bind_param("s",$img); //execute DELETE query $delete->execute(); if ($delete->errno) { // Handle query error here } //close query $delete->close(); ?> Can you please provide an sample code in your answer to make it easier for me. Thank you

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• Empty database output in CI

  - by den-javamaniac

  Hi. I'm building a simple app and trying to test DB result output. But unfortunately all I'm getting is an array of size 0. Here's the controller code excerpt: $data['query'] = $this->db->query('SELECT role_id, role_privilege FROM role'); $this->load->view('welcome_message', $data); And a view code excerpt: <?php echo count($query->result_array())."<br/>"; foreach ($query->result() as $row){ echo $row->role_id . '<br/>'; echo $row->role_privilege . '<br/>'; } echo 'Total result '.$query->num_rows(); ?> And what I get is next: 0 Total result Running query from a command line gives a 2 rowed output. Can someone point out what i'm missing?

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• How many results were returned?

  - by Pastor Bones

  I'm performing a query on a worksheet. I want to update the row if it exists or insert it if it doesn't. How can you check if a result was returned or not? $query = new Zend_Gdata_Spreadsheets_ListQuery(); $query->setSpreadsheetKey($this->currKey); $query->setWorksheetId($this->currWkshtId); $query->setSpreadsheetQuery('cid = ' . $data['cid']); $listFeed = $this->gdClient->getListFeed($query); // This does not work! if(empty($listFeed)){ echo 'No results found!'; }

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• Parallelism in .NET – Part 10, Cancellation in PLINQ and the Parallel class

  - by Reed

  Many routines are parallelized because they are long running processes.  When writing an algorithm that will run for a long period of time, its typically a good practice to allow that routine to be cancelled.  I previously discussed terminating a parallel loop from within, but have not demonstrated how a routine can be cancelled from the caller’s perspective.  Cancellation in PLINQ and the Task Parallel Library is handled through a new, unified cooperative cancellation model introduced with .NET 4.0. Cancellation in .NET 4 is based around a new, lightweight struct called CancellationToken.  A CancellationToken is a small, thread-safe value type which is generated via a CancellationTokenSource.  There are many goals which led to this design.  For our purposes, we will focus on a couple of specific design decisions: Cancellation is cooperative.  A calling method can request a cancellation, but it’s up to the processing routine to terminate – it is not forced. Cancellation is consistent.  A single method call requests a cancellation on every copied CancellationToken in the routine. Let’s begin by looking at how we can cancel a PLINQ query.  Supposed we wanted to provide the option to cancel our query from Part 6: double min = collection .AsParallel() .Min(item => item.PerformComputation()); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } We would rewrite this to allow for cancellation by adding a call to ParallelEnumerable.WithCancellation as follows: var cts = new CancellationTokenSource(); // Pass cts here to a routine that could, // in parallel, request a cancellation try { double min = collection .AsParallel() .WithCancellation(cts.Token) .Min(item => item.PerformComputation()); } catch (OperationCanceledException e) { // Query was cancelled before it finished } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Here, if the user calls cts.Cancel() before the PLINQ query completes, the query will stop processing, and an OperationCanceledException will be raised.  Be aware, however, that cancellation will not be instantaneous.  When cts.Cancel() is called, the query will only stop after the current item.PerformComputation() elements all finish processing.  cts.Cancel() will prevent PLINQ from scheduling a new task for a new element, but will not stop items which are currently being processed.  This goes back to the first goal I mentioned – Cancellation is cooperative.  Here, we’re requesting the cancellation, but it’s up to PLINQ to terminate. If we wanted to allow cancellation to occur within our routine, we would need to change our routine to accept a CancellationToken, and modify it to handle this specific case: public void PerformComputation(CancellationToken token) { for (int i=0; i<this.iterations; ++i) { // Add a check to see if we've been canceled // If a cancel was requested, we'll throw here token.ThrowIfCancellationRequested(); // Do our processing now this.RunIteration(i); } } With this overload of PerformComputation, each internal iteration checks to see if a cancellation request was made, and will throw an OperationCanceledException at that point, instead of waiting until the method returns.  This is good, since it allows us, as developers, to plan for cancellation, and terminate our routine in a clean, safe state. This is handled by changing our PLINQ query to: try { double min = collection .AsParallel() .WithCancellation(cts.Token) .Min(item => item.PerformComputation(cts.Token)); } catch (OperationCanceledException e) { // Query was cancelled before it finished } PLINQ is very good about handling this exception, as well.  There is a very good chance that multiple items will raise this exception, since the entire purpose of PLINQ is to have multiple items be processed concurrently.  PLINQ will take all of the OperationCanceledException instances raised within these methods, and merge them into a single OperationCanceledException in the call stack.  This is done internally because we added the call to ParallelEnumerable.WithCancellation. If, however, a different exception is raised by any of the elements, the OperationCanceledException as well as the other Exception will be merged into a single AggregateException. The Task Parallel Library uses the same cancellation model, as well.  Here, we supply our CancellationToken as part of the configuration.  The ParallelOptions class contains a property for the CancellationToken.  This allows us to cancel a Parallel.For or Parallel.ForEach routine in a very similar manner to our PLINQ query.  As an example, we could rewrite our Parallel.ForEach loop from Part 2 to support cancellation by changing it to: try { var cts = new CancellationTokenSource(); var options = new ParallelOptions() { CancellationToken = cts.Token }; Parallel.ForEach(customers, options, customer => { // Run some process that takes some time... DateTime lastContact = theStore.GetLastContact(customer); TimeSpan timeSinceContact = DateTime.Now - lastContact; // Check for cancellation here options.CancellationToken.ThrowIfCancellationRequested(); // If it's been more than two weeks, send an email, and update... if (timeSinceContact.Days > 14) { theStore.EmailCustomer(customer); customer.LastEmailContact = DateTime.Now; } }); } catch (OperationCanceledException e) { // The loop was cancelled } Notice that here we use the same approach taken in PLINQ.  The Task Parallel Library will automatically handle our cancellation in the same manner as PLINQ, providing a clean, unified model for cancellation of any parallel routine.  The TPL performs the same aggregation of the cancellation exceptions as PLINQ, as well, which is why a single exception handler for OperationCanceledException will cleanly handle this scenario.  This works because we’re using the same CancellationToken provided in the ParallelOptions.  If a different exception was thrown by one thread, or a CancellationToken from a different CancellationTokenSource was used to raise our exception, we would instead receive all of our individual exceptions merged into one AggregateException.

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• Integrate Bing Search API into ASP.Net application

  - by sreejukg

  Couple of months back, I wrote an article about how to integrate Bing Search engine (API 2.0) with ASP.Net website. You can refer the article here http://weblogs.asp.net/sreejukg/archive/2012/04/07/integrate-bing-api-for-search-inside-asp-net-web-application.aspx Things are changing rapidly in the tech world and Bing has also changed! The Bing Search API 2.0 will work until August 1, 2012, after that it will not return results. Shocked? Don’t worry the API has moved to Windows Azure market place and available for you to sign up and continue using it and there is a free version available based on your usage. In this article, I am going to explain how you can integrate the new Bing API that is available in the Windows Azure market place with your website. You can access the Windows Azure market place from the below link https://datamarket.azure.com/ There is lot of applications available for you to subscribe and use. Bing is one of them. You can find the new Bing Search API from the below link https://datamarket.azure.com/dataset/5BA839F1-12CE-4CCE-BF57-A49D98D29A44 To get access to Bing Search API, first you need to register an account with Windows Azure market place. Sign in to the Windows Azure market place site using your windows live account. Once you sign in with your windows live account, you need to register to Windows Azure Market place account. From the Windows Azure market place, you will see the sign in button it the top right of the page. Clicking on the sign in button will take you to the Windows live ID authentication page. You can enter a windows live ID here to login. Once logged in you will see the Registration page for the Windows Azure market place as follows. You can agree or disagree for the email address usage by Microsoft. I believe selecting the check box means you will get email about what is happening in Windows Azure market place. Click on continue button once you are done. In the next page, you should accept the terms of use, it is not optional, you must agree to terms and conditions. Scroll down to the page and select the I agree checkbox and click on Register Button. Now you are a registered member of Windows Azure market place. You can subscribe to data applications. In order to use BING API in your application, you must obtain your account Key, in the previous version of Bing you were required an API key, the current version uses Account Key instead. Once you logged in to the Windows Azure market place, you can see “My Account” in the top menu, from the Top menu; go to “My Account” Section. From the My Account section, you can manage your subscriptions and Account Keys. Account Keys will be used by your applications to access the subscriptions from the market place. Click on My Account link, you can see Account Keys in the left menu and then Add an account key or you can use the default Account key available. Creating account key is very simple process. Also you can remove the account keys you create if necessary. The next step is to subscribe to BING Search API. At this moment, Bing Offers 2 APIs for search. The available options are as follows. 1. Bing Search API - https://datamarket.azure.com/dataset/5ba839f1-12ce-4cce-bf57-a49d98d29a44 2. Bing Search API – Web Results only - https://datamarket.azure.com/dataset/8818f55e-2fe5-4ce3-a617-0b8ba8419f65 The difference is that the later will give you only web results where the other you can specify the source type such as image, video, web, news etc. Carefully choose the API based on your application requirements. In this article, I am going to use Web Results Only API, but the steps will be similar to both. Go to the API page https://datamarket.azure.com/dataset/8818f55e-2fe5-4ce3-a617-0b8ba8419f65, you can see the subscription options in the right side. And in the bottom of the page you can see the free option Since I am going to use the free options, just Click the Sign Up link for that. Just select I agree check box and click on the Sign Up button. You will get a recipt pagethat detail your subscription. Now you are ready Bing Search API – Web results. The next step is to integrate the API into your ASP.Net application. Now if you go to the Search API page (as well as in the Receipt page), you can see a .Net C# Class Library link, click on the link, you will get a code file named “BingSearchContainer.cs”. In the following sections I am going to demonstrate the use of Bing Search API from an ASP.Net application. Create an empty ASP.Net web application. In the solution explorer, the application will looks as follows. Now add the downloaded code file (“BingSearchContainer.cs”) to the project. Right click your project in solution explorer, Add -> existing item, then browse to the downloaded location, select the “BingSearchContainer.cs” file and add it to the project. To build the code file you need to add reference to the following library. System.Data.Services.Client You can find the library in the .Net tab, when you select Add -> Reference Try to build your project now; it should build without any errors. Add an ASP.Net page to the project. I have included a text box and a button, then a Grid View to the page. The idea is to Search the text entered and display the results in the gridview. The page will look in the Visual Studio Designer as follows. The markup of the page is as follows. In the button click event handler for the search button, I have used the following code. Now run your project and enter some text in the text box and click the Search button, you will see the results coming from Bing, cool. I entered the text “Microsoft” in the textbox and clicked on the button and I got the following results. Searching Specific Websites If you want to search a particular website, you pass the site url with site:<site url name> and if you have more sites, use pipe (|). e.g. The following search query site:microsoft.com | site:adobe.com design will search the word design and return the results from Microsoft.com and Adobe.com See the sample code that search only Microsoft.com for the text entered for the above sample. var webResults = bingContainer.Web("site:www.Microsoft.com " + txtSearch.Text, null, null, null, null, null, null); Paging the results returned by the API By default the BING API will return 100 results based on your query. The default code file that you downloaded from BING doesn’t include any option for this. You can modify the downloaded code to perform this paging. The BING API supports two parameters $top (for number of results to return) and $skip (for number of records to skip). So if you want 3rd page of results with page size = 10, you need to pass $top = 10 and $skip=20. Open the BingSearchContainer.cs in the editor. You can see the Web method in it as follows. public DataServiceQuery<WebResult> Web(String Query, String Market, String Adult, Double? Latitude, Double? Longitude, String WebFileType, String Options) {  In the method signature, I have added two more parameters public DataServiceQuery<WebResult> Web(String Query, String Market, String Adult, Double? Latitude, Double? Longitude, String WebFileType, String Options, int resultCount, int pageNo) { and in the method, you need to pass the parameters to the query variable. query = query.AddQueryOption("$top", resultCount); query = query.AddQueryOption("$skip", (pageNo -1)*resultCount); return query; Note that I didn’t perform any validation, but you need to check conditions such as resultCount and pageCount should be greater than or equal to 1. If the parameters are not valid, the Bing Search API will throw the error. The modified method is as follows. The changes are highlighted. Now see the following code in the SearchPage.aspx.cs file protected void btnSearch_Click(object sender, EventArgs e) {     var bingContainer = new Bing.BingSearchContainer(new Uri(https://api.datamarket.azure.com/Bing/SearchWeb/));     // replace this value with your account key     var accountKey = "your key";     // the next line configures the bingContainer to use your credentials.     bingContainer.Credentials = new NetworkCredential(accountKey, accountKey);     var webResults = bingContainer.Web("site:microsoft.com" +txtSearch.Text , null, null, null, null, null, null,3,2);     lstResults.DataSource = webResults;     lstResults.DataBind(); } The following code will return 3 results starting from second page (by skipping first 3 results). See the result page as follows. Bing provides complete integration to its offerings. When you develop search based applications, you can use the power of Bing to perform the search. Integrating Bing Search API to ASP.Net application is a simple process and without investing much time, you can develop a good search based application. Make sure you read the terms of use before designing the application and decide which API usage is suitable for you. Further readings BING API Migration Guide http://go.microsoft.com/fwlink/?LinkID=248077 Bing API FAQ http://go.microsoft.com/fwlink/?LinkID=252146 Bing API Schema Guide http://go.microsoft.com/fwlink/?LinkID=252151

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• SmartAssembly Support: How to change the maps folder

  - by Bart Read

  If you've set up SmartAssembly to store error reports in a SQL Server database, you'll also have specified a folder for the map files that are used to de-obfuscate error reports (see Figure 1). Whilst you can change the database easily enough you can't change the map folder path via the UI - if you click on it, it'll just open the folder in Explorer - but never fear, you can change it manually and fortunately it's not that difficult. (If you want to get to these settings click the Tools > Options link on the left-hand side of the SmartAssembly main window.)   Figure 1. Error reports database settings in SmartAssembly. The folder path is actually stored in the database, so you just need to open up SQL Server Management Studio, connect to the SQL Server where your error reports database is stored, then open a new query on the SmartAssembly database by right-clicking on it in the Object Explorer, then clicking New Query (see figure 2).     Figure 2. Opening a new query against the SmartAssembly error reports database in SQL Server. Now execute the following SQL query in the new query window: SELECT * FROM dbo.Information You should find that you get a result set rather like that shown in figure 3. You can see that the map folder path is stored in the MapFolderNetworkPath column.   Figure 3. Contents of the dbo.Information table, showing the map folder path I set in SmartAssembly. All I need to do to change this is execute the following SQL: UPDATE dbo.Information SET MapFolderNetworkPath = '\\UNCPATHTONEWFOLDER' WHERE MapFolderNetworkPath = '\\dev-ltbart\SAMaps' This will change the map folder path to whatever I supply in the SET clause. Once you've done this, you can verify the change by executing the following again: SELECT * FROM dbo.Information You should find the result set contains the new path you've set.

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