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  • Weird GWT issue causing IE threads to skyrocket.

    - by WesleyJohnson
    I'm not sure if this is an issue with GWT, JavaScript, Java, IE or just poor programming, but I'll try to explain. We're implementing web based chat program at work and some of our users have unreliable connections. So we're running into issues where they send out a new message and after x number of milliseconds have passed, the XHR request timesout and the client tries to resend the message again. The issue we ran into was sometimes the message would make it to the server and into the DB, but the XHR request wouldn't make it back to the client so the client was essentially retrying requests that had alread made it to the server. To mitigate this issue, we now send along a count/key with the message. The client says, hey I'm sending msg 50 and it's text is this. If the server already has that message, it just sends back "ok, I got it" and doens't insert into the DB again, eliminating dupes. So the client is free to keep retrying over and over until finally a call comes back from the server saying "Ok, I got it" and then it increments the key and moves on (or we keep them out of the chat if it fails enough). Anyway, so that's the background of what we're doing. The issue is, when we add this code on some versions of IE the threads start increasing gradually everytime it's accessed. On IE8 for Windows7 x64 it doesn't really seem to do it, but on IE8 for Windows Vista x86 it does. So I can't really pinpoint if it's a fluke or my code. Maybe someone had some ideas on a better way to do this. Here is some pseudo code: (the issue seems appear where I increment messageCount? Is this a scope thing, naming conflict, maybe the issue is entirely somewhere else and I'm way off base. public class SFChatClient implements EntryPoint { private List<String> messageQueue; private Integer messageCount = 0; public void onModuleLoad() { messageQueue = new ArrayList<String>(); // setup ui and what not // add a keyhandler to an input box that checks for <ENTER> and calls sendMEssage() } private void sendMessage() { // add message content to the UI for the chat messageQueue.add( //get message from user ); sendQueuedMessages(); } private void sendQueuedMessages() { if( messageQueue.size() > 0 ) { String outgoingMessage = messageQueue.get( 0 ); WebServiceClass.sendMessage( outgoingMessage, messageCount, new WebServiceHandler() { public void onSuccess() { // Delete item 0 from messageQueue messageCount = messageCount + 1; // <--- this seems to cause IE to leak threads. Taking out this code stops the issue??? sendQueuedMessages(); } public void onError() { // Do error handling sendQueuedMessages(); } } ); } } } public class WebServiceClass() { public void sendMessage( String message, Integer messageCount, handler ) { RequestBuilder builder = new RequestBuilder(// create request builder with proper params for the web service url, JSON content type, etc ) { public void onSuccess() { handler.onSuccess() } public void onError() { handler.onError() } } builder.setData( // JSON with message ); bulder.send(); } }

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  • Get backreferences values and modificate these values

    - by roasted
    Could you please explain why im not able to get values of backreferences from a matched regex result and apply it some modification before effective replacement? The expected result is replacing for example string ".coord('X','Y')" by "X * Y". But if X to some value, divide this value by 2 and then use this new value in replacement. Here the code im currently testing: See /*>>1<<*/ & /*>>2<<*/ & /*>>3<<*/, this is where im stuck! I would like to be able to apply modification on backrefrences before replacement depending of backreferences values. Difference between /*>>2<<*/ & /*>>3<<*/ is just the self call anonymous function param The method /*>>2<<*/ is the expected working solution as i can understand it. But strangely, the replacement is not working correctly, replacing by alias $1 * $2 and not by value...? You can test the jsfiddle //string to test ".coord('125','255')" //array of regex pattern and replacement //just one for the example //for this example, pattern matching alphanumerics is not necessary (only decimal in coord) but keep it as it var regexes = [ //FORMAT is array of [PATTERN,REPLACEMENT] /*.coord("X","Y")*/ [/\.coord\(['"]([\w]+)['"],['"]?([\w:\.\\]+)['"]?\)/g, '$1 * $2'] ]; function testReg(inputText, $output) { //using regex for (var i = 0; i < regexes.length; i++) { /*==>**1**/ //this one works as usual but dont let me get backreferences values $output.val(inputText.replace(regexes[i][0], regexes[i][2])); /*==>**2**/ //this one should works as i understand it $output.val(inputText.replace(regexes[i][0], function(match, $1, $2, $3, $4) { $1 = checkReplace(match, $1, $2, $3, $4); //here want using $1 modified value in replacement return regexes[i][3]; })); /*==>**3**/ //this one is just a test by self call anonymous function $output.val(inputText.replace(regexes[i][0], function(match, $1, $2, $3, $4) { $1 = checkReplace(match, $1, $2, $3, $4); //here want using $1 modified value in replacement return regexes[i][4]; }())); inputText = $output.val(); } } function checkReplace(match, $1, $2, $3, $4) { console.log(match + ':::' + $1 + ':::' + $2 + ':::' + $3 + ':::' + $4); //HERE i should be able if lets say $1 > 200 divide it by 2 //then returning $1 value if($1 > 200) $1 = parseInt($1 / 2); return $1; }? Sure I'm missing something, but cannot get it! Thanks for your help, regards. EDIT WORKING METHOD: Finally get it, as mentionned by Eric: The key thing is that the function returns the literal text to substitute, not a string which is parsed for backreferences.?? JSFIDDLE So complete working code: (please note as pattern replacement will change for each matched pattern and optimisation of speed code is not an issue here, i will keep it like that) $('#btn').click(function() { testReg($('#input').val(), $('#output')); }); //array of regex pattern and replacement //just one for the example var regexes = [ //FORMAT is array of [PATTERN,REPLACEMENT] /*.coord("X","Y")*/ [/\.coord\(['"]([\w]+)['"],['"]?([\w:\.\\]+)['"]?\)/g, '$1 * $2'] ]; function testReg(inputText, $output) { //using regex for (var i = 0; i < regexes.length; i++) { $output.val(inputText.replace(regexes[i][0], function(match, $1, $2, $3, $4) { var checkedValues = checkReplace(match, $1, $2, $3, $4); $1 = checkedValues[0]; $2 = checkedValues[1]; regexes[i][1] = regexes[i][1].replace('$1', $1).replace('$2', $2); return regexes[i][1]; })); inputText = $output.val(); } } function checkReplace(match, $1, $2, $3, $4) { console.log(match + ':::' + $1 + ':::' + $2 + ':::' + $3 + ':::' + $4); if ($1 > 200) $1 = parseInt($1 / 2); if ($2 > 200) $2 = parseInt($2 / 2); return [$1,$2]; }

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  • Sorting linked lists in Pascal

    - by user3712174
    I'm doing my final project for Informatics class and I can't get my sorting procedure to work. Have a look at my program, specifically the bolded part (some things are in Croatian. - if you need something translated, let me know): type pokazivac=^slog; slog=record prezime_ime:string[30]; redni_broj:string[2]; fakultet:string[50]; bodovi:integer; sljedeci:pokazivac; end; var pocetni, trenutni, prethodni:pokazivac; i:integer; procedure racunaj; var i,a,c:integer; b,d,e,f,g,h,j:real; begin write('Postotak bodova (u decimalnom zapisu) koje ucenik ostvaruje na temelju prosjeka ocjena - '); readln(e); e:=e*1000/4; write('Prosjek ocjena u prvom razredu : '); readln(f); f:=f/5*e; write('Prosjek ocjena u drugom razredu : '); readln(g); g:=g/5*e; write('Prosjek ocjena u trecem razredu : '); readln(h); h:=h/5*e; write('Prosjek ocjena u cetvrtom razredu : '); readln(j); j:=j/5*e; d:=f+g+h+j; write('Broj predmeta (ne racunajuci hrvatski jezik, strani jezik i matematiku) koju je ucenik/ca polagao na maturi - '); readln(a); write('Postotak rijesnosti ispita iz hrvatskog jezika te zatim maksimum bodova koje je ucenik/ca mogao ostvariti - '); readln(b); readln(c); d:=d+b*c; write('Postotak rijesnosti ispita iz stranog jezika te zatim maksimum bodova koje je ucenik/ca mogao ostvariti - '); readln(b); readln(c); d:=d+(b*c); write('Postotak rijesnosti ispita iz matematike te zatim maksimum bodova koje je ucenik/ca mogao ostvariti - '); readln(b); readln(c); d:=d+(b*c); for i:=1 to a do begin writeln('Postotak rijesnosti dodatnog predmeta te zatim maksimum bodova koje je ucenik/ca mogao ostvariti - '); readln(b); readln(c); d:=d+(b*c); end; d:=round(d); writeln('Vas broj bodova je: ', d:4:2); write('Za nastavak pritisnite ENTER..'); readln; end; procedure unos; begin new(trenutni); write('Redni broj ucenika - ');readln(trenutni^.redni_broj); write('Prezime i ime - ');readln(trenutni^.prezime_ime); write('Naziv fakultet - ');readln(trenutni^.fakultet); write('Bodovi - ');readln(trenutni^.bodovi); trenutni^.sljedeci:=pocetni; pocetni:=trenutni; end; procedure ispis; begin writeln(); writeln('Lista popisanih ucenika:'); writeln(); trenutni:=pocetni; while trenutni<>NIL do begin with trenutni^do begin writeln('IME: ',prezime_ime); writeln('FAKULTET: ',fakultet); writeln('BODOVI: ',bodovi); writeln(); end; trenutni:=trenutni^.sljedeci; end; writeln(); write('Za nastavak pritisnite ENTER..'); readln; end; procedure brisi; var s:string; begin trenutni:= pocetni; prethodni:=pocetni; write('Redni broj ucenika kojeg zelite izbrisati - '); readln(s); while trenutni<>NIL do begin if trenutni^.redni_broj=s then begin prethodni^.sljedeci:=trenutni^.sljedeci; dispose(trenutni); break; end; trenutni:=trenutni^.sljedeci; end; end; procedure izmjeni; var s:string; begin trenutni:=pocetni; write('Redni broj ucenika cije podatke zelite izmijeniti - '); readln(s); while trenutni<> NIL do begin if trenutni^.redni_broj=s then begin write(trenutni^.prezime_ime, ' - '); readln(trenutni^.prezime_ime); write(trenutni^.fakultet, ' - '); readln(trenutni^.fakultet); write(trenutni^.bodovi, ' - '); readln(trenutni^.bodovi); break; end; trenutni:=trenutni^.sljedeci; end; end; **procedure sortiraj; var t1,t2,t:pokazivac; begin t1:=pocetni; while t1 <> NIL do begin t2:=t1^.sljedeci; while t2<>NIL do if t2^.bodovi<t1^.bodovi then begin new(t); t^.redni_broj:=t1^.redni_broj; t^.prezime_ime:=t1^.prezime_ime; t^.fakultet:=t1^.fakultet; t^.bodovi:=t1^.bodovi; t1^.redni_broj:=t2^.redni_broj; t1^.prezime_ime:=t2^.prezime_ime; t1^.fakultet:=t2^.fakultet; t1^.bodovi:=t2^.bodovi; t2^.redni_broj:=t^.redni_broj; t2^.prezime_ime:=t^.prezime_ime; t2^.fakultet:=t^.fakultet; t2^.bodovi:=t^.bodovi; dispose(t); end; t2:=t2^.sljedeci; end; t1:=t1^.sljedeci; write('Za nastavak pritisnite ENTER..'); readln; end;** begin pocetni:=NIL; trenutni:=NIL; writeln('******************************************'); writeln('**********DOBRODOSLI U FAX-O-MAT**********'); writeln('******************************************'); repeat writeln('1 - Racunaj broj bodova'); writeln('2 - Dodaj ucenika'); writeln('3 - Brisi ucenika'); writeln('4 - Ispis liste'); writeln('5 - Izmjeni podatke'); writeln('6 - Sortiraj listu prema broju bodova'); writeln('0 - Kraj'); readln(i); case i of 1:racunaj; 2:unos; 3:brisi; 4:ispis; 5:izmjeni; 6:sortiraj; end; until i=0; end. Either it crashes with a fatal error, or when I press the number 6, nothing happens. The pointer keeps blinking and I can't enter any more numbers.

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  • makecert gives "Fail to acquire a security provider from the issuer's certificate" - why?

    - by mark
    Dear ladies and sirs. Observe this simple batch file: makecert -n "CN=MyCA" -sr localmachine -ss root -a sha1 -cy authority -r -sv MyCA.pvk MyCA.cer del MyCA.pvk del MyCA.cer makecert -n "CN=il-mark-lt" -sr localmachine -ss my -cy end -pe -sky exchange -a sha1 -is root -ir localmachine -in MyCA However, the last makecert fails with the following error message: Error: Fail to acquire a security provider from the issuer's certificate How do I troubleshoot it? Any ideas? BTW, the first makecert succeeds. Of course, I delete it again, before running the commands again. Thanks. EDIT1 I understood the reasons for the failure. The second command expects the file MyCA.pvk to exist, but I do not want to keep it around. So, what can I do?

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  • Can't send FB Notifications with new API

    - by Zak Khalique
    Really need some help with this one! I'm trying to send notifications from a canvas app using the new notifications API but I keep getting the following exception: OAuthException: (#200) Only web canvas apps can send app notifications However, the app IS loaded in the Facebook canvas -- I'm making an ajax call to my server when the user takes a particular action which triggers the notification POST request. The user has also authorized the app. This is the code I'm using: $graphUrl = $user_id . "/notifications"; $params = array( "access_token" => $admintoken, "href" => $link, "template" => "string of text < 180 chars" ); try { $result = $facebook->_graph($graphUrl, 'POST', $params); } catch (Exception $e){ echo $e; }

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  • VBA WinHTTPRequest and submitting forms

    - by Hazerider
    Hi. I spent all day yesterday trying to figure out how to submit a form using WinHTTPRequest. I can do it pretty easily with an InternetExplorer object, but the problem is that I need to save a PDF file that gets returned, and I am not sure how to do this with the IE object. Here is the relevant HTML code snippet: <div class="loginHome-left"> <fieldset> <h3>Log in Using</h3> <form> <label for="standardLogin" accesskey="s"> <input name="useLogin" id="standardLogin" value="standard" type="radio" checked="true">Standard Login</label> &nbsp; <label for="rsaSecurID" accesskey="r"> <input name="useLogin" value="rsaSecur" type="radio" id="rsaSecurID" onclick="redirectLogin('ct_logon_securid');return false;">RSA SecurID</label> &nbsp; <label for="employeeNTXP" accesskey="e"> <input name="useLogin" id="employeeNTXP" value="employee" type="radio" onclick="redirectLogin('ct_logon_external_nt');return false; "> Employee Windows Login<br></label> </form> <br> <div class="error">Error: ...</div><br> <form onSubmit="if(validate(this)) {formSubmit();} return false;" name="passwdForm" method="post" action="/UAB/ct_logon"> <input value="custom" name="pageId" type="hidden"> <input value="custom" name="auth_mode" type="hidden"> <input value="/UAB/ct_logon" name="ct_orig_uri" type="hidden"> <INPUT VALUE="" NAME="orig_url" TYPE="hidden"> <input value="" name="lpSp" type="hidden"> <label for="user"> <strong>Username</strong> </label> <input autocomplete="off" name="user" type="text" value="" class="txtFld" onkeypress="return handleEnter(this, event);"> <br> <label for="EnterPassword"> <strong>Password</strong>&nbsp;&nbsp;(<a tabindex="-1" href="/UAB/BCResetWithSecrets">Forgot Your Password?</a>) </label> <input autocomplete="off" name="password" type="password" class="txtFld" onkeypress="return handleEnter(this, event);"> <INPUT id="rememberLogin" name="lpCookie" type="checkbox"> <label for="rememberLogin">Remember My Login Information</label><br> </form> <div class="right"> <br> <input type="image" src="/BC_S/images/bclogin/btn_login.gif" name="" value="Submit" onClick="if(validate(document.forms['passwdForm'])){formSubmit();}return false;"> </div> <div class="clearfix"></div> </fieldset> </div> In order to log in through InternetExplorer, I do the following: Sub TestLogin() Dim ie As InternetExplorer, doc As HTMLDocument, form As HTMLFormElement, inp As Variant Set ie = New InternetExplorer ie.Visible = True ie.navigate "https://URL of the login page" Do Until ie.readyState = READYSTATE_COMPLETE Loop Set doc = ie.document For Each form In doc.forms If InStr(form.innerText, "Password") <> 0 Then form.elements("user").Value = "my_name" form.elements("password").Value = "my_password" Exit For Else End If Next 'This is the unnamed input with an image that is used to submit the form' doc.all(78).Click ie.navigate "https://url of the PDF" Do Until ie.readyState = READYSTATE_COMPLETE Loop Dim filename As String, filenum As Integer filename = "somefile.pdf" filenum = FreeFile Open filename For Binary Access Write As #filenum Write #filenum, doc.DocumentElement.innerText Close #filenum ie.Quit Debug.Print Set ie = Nothing End Sub What I really would like to do is something along the lines of the following: Sub TestLogin3() Dim whr As New WinHttpRequest, postData As String whr.Open "POST", "https://live.barcap.com/UAB/ct_logon", False whr.setRequestHeader "User-Agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)" whr.setRequestHeader "Connection", "Keep-Alive" whr.Send whr.WaitForResponse postData = "user=paschom1&password=change01" 'Or the following?' postData = "user=paschom1&password=change01&orig_url=&pageId=custom&auth_mode=custom&ct_orig_uri=/BC/dispatcher&lpSp=&lpCookie=off" whr.Send postData whr.WaitForResponse Debug.Print whr.responseText End Sub It just refuses to work though. Not sure if I need to use more setRequestHeader with Content-Form or something similar, and if I do, not sure what exactly I am supposed to pass it. If anyone has any advice regarding this, it would be hugely appreciated. I could probably use a perl module to do it, but I would rather keep it all in VBA if possible. Thanks, Marc.

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  • 'Element is already the child of another element' error in Silverlight App.xaml

    - by rwwilden
    Hi, I keep getting a strange error inside my App.xaml file: Element is already the child of another element. My App.xaml file looks like this: <Application xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" x:Class="Celerior.Annapurna.SL.App"> <Application.Resources> <ResourceDictionary> <ResourceDictionary.MergedDictionaries> <ResourceDictionary Source="ProvisiorResourceDictionary.xaml"/> </ResourceDictionary.MergedDictionaries> </ResourceDictionary> </Application.Resources> </Application> The error is reported for the entire ResourceDictionary element (from lines 5 to 9). ProvisiorResourceDictionary.xaml contains a number of styles and templates. Nothing exciting in my opinion. Does anyone know what is wrong? Kind regards, Ronald Wildenberg

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  • XML parsing error: 'A string literal was expected' when inserting values into table

    - by Christian
    In Microsoft Sequel Server 2008 I am attempting to insert values into an sql table with the columns type_id of datatype int and xml_info of datatype XML. I am using the following query: INSERT INTO tbl_applied_devices ([type_id],[xml_info]) VALUES (1,'<Profile ID=99><Server><ID>BC4A18CA-AFB5-4268-BDA9-C990DAFE7783</ID> <Name>localhost</Name><Services></Services></Server></Profile>') But I keep getting this error: Msg 9413, Level 16, State 1, Line 4 XML parsing: line 1, character 13, A string literal was expected What am I doing incorrectly? Thank you for the help. EDIT: I found that the source of the error is the xml element's ID attribute, where seems to be what is causing the error. How can I correctly insert xml with an attribute ? Do I need to somehow escape one of the characters?

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  • Find multiple regex in each line and skip result if one of the regex doesn't match

    - by williamx
    I have a list of variables: variables = ['VariableA', 'VariableB','VariableC'] which I'm going to search for, line by line ifile = open("temp.txt",'r') d = {} match = zeros(len(variables)) for line in ifile: emptyCells=0 for i in range(len(variables)): regex = r'('+variables[i]+r')[:|=|\(](-?\d+(?:\.\d+)?)(?:\))?' pattern_variable = re.compile(regex) match[i] = re.findall(pattern_variable, line) if match[j] == []: emptyCells = emptyCells+1 if emptyCells == 0: for k, v in match[j]: d.setdefault(k, []).append(v) The requirement is that I will only keep the lines where all the regex'es matches! I want to collect all results for each variable in a dictionary where the variable name is the key, and the value becomes a list of all matches. The code provided is only what I've found out so far, and is not working perfectly yet...

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  • Where does ASP.NET Web API Fit?

    - by Rick Strahl
    With the pending release of ASP.NET MVC 4 and the new ASP.NET Web API, there has been a lot of discussion of where the new Web API technology fits in the ASP.NET Web stack. There are a lot of choices to build HTTP based applications available now on the stack - we've come a long way from when WebForms and Http Handlers/Modules where the only real options. Today we have WebForms, MVC, ASP.NET Web Pages, ASP.NET AJAX, WCF REST and now Web API as well as the core ASP.NET runtime to choose to build HTTP content with. Web API definitely squarely addresses the 'API' aspect - building consumable services - rather than HTML content, but even to that end there are a lot of choices you have today. So where does Web API fit, and when doesn't it? But before we get into that discussion, let's talk about what a Web API is and why we should care. What's a Web API? HTTP 'APIs' (Microsoft's new terminology for a service I guess)  are becoming increasingly more important with the rise of the many devices in use today. Most mobile devices like phones and tablets run Apps that are using data retrieved from the Web over HTTP. Desktop applications are also moving in this direction with more and more online content and synching moving into even traditional desktop applications. The pending Windows 8 release promises an app like platform for both the desktop and other devices, that also emphasizes consuming data from the Cloud. Likewise many Web browser hosted applications these days are relying on rich client functionality to create and manipulate the browser user interface, using AJAX rather than server generated HTML data to load up the user interface with data. These mobile or rich Web applications use their HTTP connection to return data rather than HTML markup in the form of JSON or XML typically. But an API can also serve other kinds of data, like images or other binary files, or even text data and HTML (although that's less common). A Web API is what feeds rich applications with data. ASP.NET Web API aims to service this particular segment of Web development by providing easy semantics to route and handle incoming requests and an easy to use platform to serve HTTP data in just about any content format you choose to create and serve from the server. But .NET already has various HTTP Platforms The .NET stack already includes a number of technologies that provide the ability to create HTTP service back ends, and it has done so since the very beginnings of the .NET platform. From raw HTTP Handlers and Modules in the core ASP.NET runtime, to high level platforms like ASP.NET MVC, Web Forms, ASP.NET AJAX and the WCF REST engine (which technically is not ASP.NET, but can integrate with it), you've always been able to handle just about any kind of HTTP request and response with ASP.NET. The beauty of the raw ASP.NET platform is that it provides you everything you need to build just about any type of HTTP application you can dream up from low level APIs/custom engines to high level HTML generation engine. ASP.NET as a core platform clearly has stood the test of time 10+ years later and all other frameworks like Web API are built on top of this ASP.NET core. However, although it's possible to create Web APIs / Services using any of the existing out of box .NET technologies, none of them have been a really nice fit for building arbitrary HTTP based APIs. Sure, you can use an HttpHandler to create just about anything, but you have to build a lot of plumbing to build something more complex like a comprehensive API that serves a variety of requests, handles multiple output formats and can easily pass data up to the server in a variety of ways. Likewise you can use ASP.NET MVC to handle routing and creating content in various formats fairly easily, but it doesn't provide a great way to automatically negotiate content types and serve various content formats directly (it's possible to do with some plumbing code of your own but not built in). Prior to Web API, Microsoft's main push for HTTP services has been WCF REST, which was always an awkward technology that had a severe personality conflict, not being clear on whether it wanted to be part of WCF or purely a separate technology. In the end it didn't do either WCF compatibility or WCF agnostic pure HTTP operation very well, which made for a very developer-unfriendly environment. Personally I didn't like any of the implementations at the time, so much so that I ended up building my own HTTP service engine (as part of the West Wind Web Toolkit), as have a few other third party tools that provided much better integration and ease of use. With the release of Web API for the first time I feel that I can finally use the tools in the box and not have to worry about creating and maintaining my own toolkit as Web API addresses just about all the features I implemented on my own and much more. ASP.NET Web API provides a better HTTP Experience ASP.NET Web API differentiates itself from the previous Microsoft in-box HTTP service solutions in that it was built from the ground up around the HTTP protocol and its messaging semantics. Unlike WCF REST or ASP.NET AJAX with ASMX, it’s a brand new platform rather than bolted on technology that is supposed to work in the context of an existing framework. The strength of the new ASP.NET Web API is that it combines the best features of the platforms that came before it, to provide a comprehensive and very usable HTTP platform. Because it's based on ASP.NET and borrows a lot of concepts from ASP.NET MVC, Web API should be immediately familiar and comfortable to most ASP.NET developers. Here are some of the features that Web API provides that I like: Strong Support for URL Routing to produce clean URLs using familiar MVC style routing semantics Content Negotiation based on Accept headers for request and response serialization Support for a host of supported output formats including JSON, XML, ATOM Strong default support for REST semantics but they are optional Easily extensible Formatter support to add new input/output types Deep support for more advanced HTTP features via HttpResponseMessage and HttpRequestMessage classes and strongly typed Enums to describe many HTTP operations Convention based design that drives you into doing the right thing for HTTP Services Very extensible, based on MVC like extensibility model of Formatters and Filters Self-hostable in non-Web applications  Testable using testing concepts similar to MVC Web API is meant to handle any kind of HTTP input and produce output and status codes using the full spectrum of HTTP functionality available in a straight forward and flexible manner. Looking at the list above you can see that a lot of functionality is very similar to ASP.NET MVC, so many ASP.NET developers should feel quite comfortable with the concepts of Web API. The Routing and core infrastructure of Web API are very similar to how MVC works providing many of the benefits of MVC, but with focus on HTTP access and manipulation in Controller methods rather than HTML generation in MVC. There’s much improved support for content negotiation based on HTTP Accept headers with the framework capable of detecting automatically what content the client is sending and requesting and serving the appropriate data format in return. This seems like such a little and obvious thing, but it's really important. Today's service backends often are used by multiple clients/applications and being able to choose the right data format for what fits best for the client is very important. While previous solutions were able to accomplish this using a variety of mixed features of WCF and ASP.NET, Web API combines all this functionality into a single robust server side HTTP framework that intrinsically understands the HTTP semantics and subtly drives you in the right direction for most operations. And when you need to customize or do something that is not built in, there are lots of hooks and overrides for most behaviors, and even many low level hook points that allow you to plug in custom functionality with relatively little effort. No Brainers for Web API There are a few scenarios that are a slam dunk for Web API. If your primary focus of an application or even a part of an application is some sort of API then Web API makes great sense. HTTP ServicesIf you're building a comprehensive HTTP API that is to be consumed over the Web, Web API is a perfect fit. You can isolate the logic in Web API and build your application as a service breaking out the logic into controllers as needed. Because the primary interface is the service there's no confusion of what should go where (MVC or API). Perfect fit. Primary AJAX BackendsIf you're building rich client Web applications that are relying heavily on AJAX callbacks to serve its data, Web API is also a slam dunk. Again because much if not most of the business logic will probably end up in your Web API service logic, there's no confusion over where logic should go and there's no duplication. In Single Page Applications (SPA), typically there's very little HTML based logic served other than bringing up a shell UI and then filling the data from the server with AJAX which means the business logic required for data retrieval and data acceptance and validation too lives in the Web API. Perfect fit. Generic HTTP EndpointsAnother good fit are generic HTTP endpoints that to serve data or handle 'utility' type functionality in typical Web applications. If you need to implement an image server, or an upload handler in the past I'd implement that as an HTTP handler. With Web API you now have a well defined place where you can implement these types of generic 'services' in a location that can easily add endpoints (via Controller methods) or separated out as more full featured APIs. Granted this could be done with MVC as well, but Web API seems a clearer and more well defined place to store generic application services. This is one thing I used to do a lot of in my own libraries and Web API addresses this nicely. Great fit. Mixed HTML and AJAX Applications: Not a clear Choice  For all the commonality that Web API and MVC share they are fundamentally different platforms that are independent of each other. A lot of people have asked when does it make sense to use MVC vs. Web API when you're dealing with typical Web application that creates HTML and also uses AJAX functionality for rich functionality. While it's easy to say that all 'service'/AJAX logic should go into a Web API and all HTML related generation into MVC, that can often result in a lot of code duplication. Also MVC supports JSON and XML result data fairly easily as well so there's some confusion where that 'trigger point' is of when you should switch to Web API vs. just implementing functionality as part of MVC controllers. Ultimately there's a tradeoff between isolation of functionality and duplication. A good rule of thumb I think works is that if a large chunk of the application's functionality serves data Web API is a good choice, but if you have a couple of small AJAX requests to serve data to a grid or autocomplete box it'd be overkill to separate out that logic into a separate Web API controller. Web API does add overhead to your application (it's yet another framework that sits on top of core ASP.NET) so it should be worth it .Keep in mind that MVC can generate HTML and JSON/XML and just about any other content easily and that functionality is not going away, so just because you Web API is there it doesn't mean you have to use it. Web API is not a full replacement for MVC obviously either since there's not the same level of support to feed HTML from Web API controllers (although you can host a RazorEngine easily enough if you really want to go that route) so if you're HTML is part of your API or application in general MVC is still a better choice either alone or in combination with Web API. I suspect (and hope) that in the future Web API's functionality will merge even closer with MVC so that you might even be able to mix functionality of both into single Controllers so that you don't have to make any trade offs, but at the moment that's not the case. Some Issues To think about Web API is similar to MVC but not the Same Although Web API looks a lot like MVC it's not the same and some common functionality of MVC behaves differently in Web API. For example, the way single POST variables are handled is different than MVC and doesn't lend itself particularly well to some AJAX scenarios with POST data. Code Duplication I already touched on this in the Mixed HTML and Web API section, but if you build an MVC application that also exposes a Web API it's quite likely that you end up duplicating a bunch of code and - potentially - infrastructure. You may have to create authentication logic both for an HTML application and for the Web API which might need something different altogether. More often than not though the same logic is used, and there's no easy way to share. If you implement an MVC ActionFilter and you want that same functionality in your Web API you'll end up creating the filter twice. AJAX Data or AJAX HTML On a recent post's comments, David made some really good points regarding the commonality of MVC and Web API's and its place. One comment that caught my eye was a little more generic, regarding data services vs. HTML services. David says: I see a lot of merit in the combination of Knockout.js, client side templates and view models, calling Web API for a responsive UI, but sometimes late at night that still leaves me wondering why I would no longer be using some of the nice tooling and features that have evolved in MVC ;-) You know what - I can totally relate to that. On the last Web based mobile app I worked on, we decided to serve HTML partials to the client via AJAX for many (but not all!) things, rather than sending down raw data to inject into the DOM on the client via templating or direct manipulation. While there are definitely more bytes on the wire, with this, the overhead ended up being actually fairly small if you keep the 'data' requests small and atomic. Performance was often made up by the lack of client side rendering of HTML. Server rendered HTML for AJAX templating gives so much better infrastructure support without having to screw around with 20 mismatched client libraries. Especially with MVC and partials it's pretty easy to break out your HTML logic into very small, atomic chunks, so it's actually easy to create small rendering islands that can be used via composition on the server, or via AJAX calls to small, tight partials that return HTML to the client. Although this is often frowned upon as to 'heavy', it worked really well in terms of developer effort as well as providing surprisingly good performance on devices. There's still plenty of jQuery and AJAX logic happening on the client but it's more manageable in small doses rather than trying to do the entire UI composition with JavaScript and/or 'not-quite-there-yet' template engines that are very difficult to debug. This is not an issue directly related to Web API of course, but something to think about especially for AJAX or SPA style applications. Summary Web API is a great new addition to the ASP.NET platform and it addresses a serious need for consolidation of a lot of half-baked HTTP service API technologies that came before it. Web API feels 'right', and hits the right combination of usability and flexibility at least for me and it's a good fit for true API scenarios. However, just because a new platform is available it doesn't meant that other tools or tech that came before it should be discarded or even upgraded to the new platform. There's nothing wrong with continuing to use MVC controller methods to handle API tasks if that's what your app is running now - there's very little to be gained by upgrading to Web API just because. But going forward Web API clearly is the way to go, when building HTTP data interfaces and it's good to see that Microsoft got this one right - it was sorely needed! Resources ASP.NET Web API AspConf Ask the Experts Session (first 5 minutes) © Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • How to do RLE (run length encoding) in C# on a byte array?

    - by CuriousCoder
    I am trying to XOR two bitmap files (their byte arrays) to produce a byte array that can be used to change image A into image B or vice versa. I am sending this over the network so I would like to do some basic compression before this happens. Is there a way to do RLE (run length encoding) in C# (using a built-in, or fast reliable 3rd party library) on a byte array for this purpose? Notes: If you are going to suggest an alternative to my approach please keep in mind that the decompression and transformation on the remote machine has to be as quick and efficient as possible.

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  • C# convert an IOrderedEnumerable<KeyValuePair<string, int>> into a Dictionary<string, int>

    - by Kache4
    I was following the answer to another question, and I got: // itemCounter is a Dictionary<string, int>, and I only want to keep // key/value pairs with the top maxAllowed values if (itemCounter.Count > maxAllowed) { IEnumerable<KeyValuePair<string, int>> sortedDict = from entry in itemCounter orderby entry.Value descending select entry; sortedDict = sortedDict.Take(maxAllowed); itemCounter = sortedDict.ToDictionary<string, int>(/* what do I do here? */); } Visual Studio's asking for a parameter Func<string, int> keySelector. I tried following a few semi-relevant examples I've found online and put in k => k.Key, but that gives a compiler error: 'System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string,int>>' does not contain a definition for 'ToDictionary' and the best extension method overload 'System.Linq.Enumerable.ToDictionary<TSource,TKey>(System.Collections.Generic.IEnumerable<TSource>, System.Func<TSource,TKey>)' has some invalid arguments

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  • Linq to sql Invalid column name

    - by Ivo
    I am using VS 2010 and Linq-to-sql I have deleted a couple of columns from my table, whatever I try I keep getting and "invalide column name" error with the old/deleted column when I try to insert a record. What tried: remove table,save, and drag it back on create new dblm with an other name created new project and create new dbml there Also the name of the deleted column does not exist in the generated code of the dbml anymore, but still I get an exception saying that column does not exists. Anyone got a suggestion how to solve this problem?

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  • Store XML,update record in XML,retrive a specific record in XML stored on BB device

    - by user469999
    I am writing a blackberry application where i want to store the data returned by a web service in my BB device.Earlier i was going to use SQLite for storing the data in mobile but as i googled and also did programming using SQLite and found that some BB devices dont support SQLite library and fail to create the database.Then i decided to keep the data returned by webservice in a XML format on my BB device. I just want to know is there any method or way in blackberry through which i can parse the data stored in xml,update it,or directly access a particular record stored in the xml instead of traversing the whole xml n times and finding the matched record. Please guide me as i am new to storing data in BB device.Is the approach which i am thinking to store data in XML right or shall i use something else Thanks in advance Yogesh Chaudhari

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  • Opening spreadsheet returns InMemoryUploadedFile

    - by David542
    I have a user uploading a file to a website and I need to parse the spreadsheet. Here is my code: input_file = request.FILES.get('file-upload') wb = xlrd.open_workbook(input_file) The error I keep getting is: TypeError at /upload_spreadsheet/ coercing to Unicode: need string or buffer, InMemoryUploadedFile found Why is this happening and what do I need to do to fix it? Thank you. For reference, this is how I open the file in the shell >>> import xlrd >>> xlrd.open_workbook('/Users/me/dave_example.xls') <xlrd.Book object at 0x10d9f7390>

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  • SqlCeException: The column cannot be modified. [ Column name = id ]

    - by pek
    I am simply trying to add a single row in the database but I keep getting an exception. I created a local database and added a single table: users. It consists of two columns: "id" and "name". I only made the id primary key (not auto-increment or anything else). When I run the following code: string execPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().GetName().CodeBase); string dbfile = execPath + @"\LocalDatabase.sdf"; SqlCeConnection conn = new SqlCeConnection("datasource=" + dbfile); conn.Open(); string command = "INSERT INTO users VALUES('1','pek')"; Debug.WriteLine(command); SqlCeCommand comm = conn.CreateCommand(); comm.CommandText = command; comm.ExecuteNonQuery(); I get the following Exception at "comm.ExecuteNonQuery();": SqlCeException was unhandled The column cannot be modified. [ Column name = id ] What's with the "modified" part?

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  • Example WCF XML-RPC client C# code against custom XML-RPC server implementation?

    - by mr.b
    I have built my own little custom XML-RPC server, and since I'd like to keep things simple, on both server and client side (server side PHP runs, by the way), what I would like to accomplish is to create a simplest possible client in C# using WCF. Let's say that Contract for service exposed via XML-RPC is as follows. [ServiceContract] public interface IContract { [OperationContract(Action="Ping")] string Ping(); // server returns back string "Pong" [OperationContract(Action="Echo")] string Echo(string message); // server echoes back whatever message is } So, there are two example methods, one without any arguments, and another with simple string argument, both returning strings (just for sake of example). Service is exposed via http. What's next? Thanks for reading! P.S. I have done my homework of googling around for samples and similar, but all that I could come up with are some blog-related samples that use existing (and very big) classes, which implement correct IContract (or IBlogger) interfaces, so that most of what I am interested is hidden below several layers of abstraction...

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  • MetadataException: Unable to load the specified metadata resource

    - by J. Steen
    All of a sudden I keep getting a MetadataException on instantiating my generated ObjectContext class. The connectionstring in App.Config looks correct - hasn't changed since last it worked - and I've tried regenerating a new model (edmx-file) from the underlying database with no change. Anyone have any... ideas? Edit: I haven't changed any properties, I haven't changed the name of any output assemblies, I haven't tried to embed the EDMX in the assembly. I've merely waited 10 hours from leaving work until I got back. And then it wasn't working anymore. I've tried recreating the EDMX. I've tried recreating the project. I've even tried recreating the database, from scratch. No luck, whatsoever. I'm truly stumped.

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  • Windows LiveID "Couldn't sign you out" error at sign-out

    - by Jason
    I'm implementing LiveID authentication on my website. I've done it before, but not on this particular platform, MojoPortal. The sign-in works properly, but when I attempt to sign-out, I get the error message quoted below. My browser is not blocking cookies. I get the same message when logging in to and out of, say, MSDN with a LiveID too now. I can't figure out if there's something about my site's programming that is interfering with the sign-out process of LiveID (since I believe that all (recent?) websites get sent a sign-out command) OR if live.com is just having issues lately and this is a coincidence. Couldn't sign you out We couldn't sign you out because your browser is blocking cookies. To sign out, close all of your browser windows. To keep this from happening again, change your browser's settings to allow cookies. If you don't know how to do that, see your browser's help.

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  • WPF dynamic layout: how to enforce square proportions (width equals height)?

    - by Gart
    I'm learning WPF and can't figure out how to enfore my buttons to take a square shape. Here is my XAML Markup: <Window x:Class="Example" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Height="368" Width="333"> <Window.Resources> <Style x:Key="ToggleStyle" BasedOn="{StaticResource {x:Type ToggleButton}}" TargetType="{x:Type RadioButton}"> </Style> </Window.Resources> <RadioButton Style="{StaticResource ToggleStyle}"> Very very long text </RadioButton> </Window> Specifying explicit values for Width and Height attributes seems like a wrong idea - the button should calculate its dimensions based on its contents automagically, but keep its width and height equal. Is this possible?

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  • iOS: AVQueuePlayer/AVPlayerItem 'An AVPlayerItem can occupy only one position in a player's queue at a time.'

    - by JoshDG
    I keep getting this error: 'An AVPlayerItem can occupy only one position in a player's queue at a time.' I NSLog'd the players items, and none of them seem to be equal. Further, I added this just to be sure: if([player canInsertItem:itemToAdd afterItem:nil]) [player insertItem:itemToAdd afterItem:nil]; When I wasn't sure if that would work (can have two identical items in different memory locations) I wrote a category method to test if a player contains an item or something identical to it. Yet, I'm still getting the error. I've seen several posts of people getting this error with MPMoviePlayerController, but I'm not using that custom class, just the out of the box AVQueuePlayer. Any ideas on how to fix this?

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  • C# How to get the current project directory or the bin directory and move a few level up?

    - by melaos
    Hi there, I have an ASP.Net MVC app, and i have some xsl files inside of the Content directory. I've try a few methods to get directory dynamically buy keep on coming short. So how do i get the directory to point to the Content/xsl folder? the closest that i came to was with this: this.GetType().Assembly.CodeBase which only returns the project DLL, but i can't figure out how to move up a few levels from there or what .net library to use to navigate around the path. there's no ../.. :( Basically i want to navigate to the Content/xsl folder which is at the same level of the Bin directory. Any idea? thanks.

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  • "unbound identifier" errors in scheme

    - by user186909
    Hello: I'm using drscheme from: http://www.archlinux.org/packages/extra/x86_64/drscheme/ I'm trying to work with the sample code in my textbook, but I keep getting getting "unbound identifier" errors. Is it because the scheme interpreter is not configured correctly? or is the code just plain wrong? Here are a few examples: Input: #lang scheme (define (equalimp lis1 lis2) (COND ((NULL? lis1) (NULL? lis2)) ((NULL? lis2) '()) ((EQ? (CAR lis1) (CAR lis2)) (equalimp (CDR lis1) (CDR lis2))) (ELSE '()) )) Output: Welcome to DrScheme, version 4.2.5 [3m]. Language: scheme; memory limit: 128 MB. expand: unbound identifier in module in: COND Input: #lang scheme (define (quadratic_roots a b c) (LET ( (root_part_over_2a (/ (SQRT (- (* b b) (* 4 a c))) (* 2 a))) (minus_b_over_2a (/ (- 0 b) (* 2 a))) ) (DISPLAY (+ minus_b_over_2a root_part_over_2a)) (NEWLINE) (DISPLAY (- minus_b_over_2a root_part_over_2a)) )) Output: expand: unbound identifier in module in: LET Note: I tried using LET* because I read this: stackoverflow.com/ questions/946050/using-let-in-scheme but it produces the same error. Thanks !

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  • Very large database, very small portion most being retrieved in real time

    - by ming yeow
    Hi folks, I have an interesting database problem. I have a DB that is 150GB in size. My memory buffer is 8GB. Most of my data is rarely being retrieved, or mainly being retrieved by backend processes. I would very much prefer to keep them around because some features require them. Some of it (namely some tables, and some identifiable parts of certain tables) are used very often in a user facing manner How can I make sure that the latter is always being kept in memory? (there is more than enough space for these) More info: We are on Ruby on rails. The database is MYSQL, our tables are stored using INNODB. We are sharding the data across 2 partitions. Because we are sharding it, we store most of our data using JSON blobs, while indexing only the primary keys

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  • SQL server 2008 backup error

    - by c11ada
    can any one help me, im trying to backup a database located on localhost\SQLEXPRESS but i keep getting the following error TITLE: Microsoft SQL Server Management Studio Backup failed for Server 'localhost\SqlExpress'. (Microsoft.SqlServer.SmoExtended) For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=10.0.2531.0+((Katmai_PCU_Main).090329-1045+)&EvtSrc=Microsoft.SqlServer.Management.Smo.ExceptionTemplates.FailedOperationExceptionText&EvtID=Backup+Server&LinkId=20476 ADDITIONAL INFORMATION: System.Data.SqlClient.SqlError: Cannot open backup device 'C:\backup.bak'. Operating system error 5(failed to retrieve text for this error. Reason: 15105). (Microsoft.SqlServer.Smo) For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=10.0.2531.0+((Katmai_PCU_Main).090329-1045+)&LinkId=20476 can any one explain what im doin wrong here ?? thanks

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