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  • Getting a UIImage from MySQL using PHP and jSON

    - by Daniel
    I'm developing a little news reader that retrieves the info from a website by doing a POST request to a URL. The response is a jSON object with the unread-news. E.g. the last news on the App has a timeStamp of "2013-03-01". When the user refreshes the table, it POSTS "domain.com/api/api.php?newer-than=2013-03-01". The api.php script goes to the MySQL database and fetches all the news posted after 2013-03-01 and prints them json_encoded. This is // do something to get the data in an array echo $array_of_fetched_data; for example the response would be [{"title": "new app is coming to the market", "text": "lorem ipsum dolor sit amet...", image: XXX}] the App then gets the response and parses it, obtaining an NSDictionary and adds it to a Core Data db. NSDictionary* obtainedNews = [NSJSONSerialization JSONObjectWithData:responseData options:kNilOptions error:&error]; My question is: How can I add an image to the MySQL database, store it, pass it using jSON trough a POST HTTP Request and then interpret it as an UIImage. It's clear that to store an UIImage in CoreData, they must be transform into/from NSData. How can I pass the NSData back and forth to a MySQL db using php and jSON? How should I upload the image to the db? (Serialized, as a BLOB, etc)

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  • Reading JSON with Javascript/jQuery

    - by Josephine
    I'm building a game in javascript/html5 and I'm trying to build a database of locked doors in a maze that can be loaded from and overwritten to throughout gameplay. I've found a large number of tutorials online, but nothing is working. I was wondering if someone could look at what I'm trying and let me know what I'm doing wrong. My JSON file looks like this: { "doors": [ {"left":true, "right":false, "bottom":false}, {"left":false, "right":false, "bottom":false}, {"right":false, "bottom":false, "top":false}, {"left":false, "right":false, "top":false} ] } I want to build the HTML page so that when a player collides with a door it checks if its locked or not like: if (player.x < leftDoor.x + leftDoor.width && player.x + player.width > leftDoor.x && player.y < leftDoor.y + leftDoor.height && player.y + player.height > leftDoor.y) { if(doors[0].left == true) alert("door is locked"); else window.location = ( "2.html?p1="); } However I'm having trouble reading from the JSON file itself. I've tried things like: function loadJson() { $(document).ready(function() { $.getJSON('info.json', function(doors) { alert(doors[0].left); }); }); } But nothing happens, and I need to be able to access the information in the HTML as well. I'd rather use jQuery, but I'm not opposed to straight JS if it works. I've been trying to do this for ages and I'm getting absolutely no where. If someone could help that would be amazing. Thanks!

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  • parse.json of authenticated play request

    - by niklassaers
    I've set up authentication in my application like this, always allow when a username is supplied and the API-key is 123: object Auth { def IsAuthenticated(block: => String => Request[AnyContent] => Result) = { Security.Authenticated(RetrieveUser, HandleUnauthorized) { user => Action { request => block(user)(request) } } } def RetrieveUser(request: RequestHeader) = { val auth = new String(base64Decode(request.headers.get("AUTHORIZATION").get.replaceFirst("Basic", ""))) val split = auth.split(":") val user = split(0) val pass = split(1) Option(user) } def HandleUnauthorized(request: RequestHeader) = { Results.Forbidden } def APIKey(apiKey: String)(f: => String => Request[AnyContent] => Result) = IsAuthenticated { user => request => if(apiKey == "123") f(user)(request) else Results.Forbidden } } I want then to define a method in my controller (testOut in this case) that uses the request as application/json only. Now, before I added authentication, I'd say "def testOut = Action(parse.json) {...}", but now that I'm using authentication, how can I add parse.json in to the mix and make this work? def testOut = Auth.APIKey("123") { username => implicit request => var props:Map[String, JsValue] = Map[String, JsValue]() request.body match { case JsObject(fields) => { props = fields.toMap } case _ => {} // Ok("received something else: " + request.body + '\n') } if(!props.contains("UUID")) props.+("UUID" -> UniqueIdGenerator.uuid) if (!props.contains("entity")) props.+("entity" -> "unset") props.+("username" -> username) Ok(props.toString) } As a bonus question, why is only UUID added to the props map, not entity and username? Sorry about the noob factor, I'm trying to learn Scala and Play at the same time. :-) Cheers Nik

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  • How to display data in spinner from json

    - by user1605913
    I am retrieving values from a json url and then storing it in a string variable. Now I want to display that value in a spinner. I have created an array list in my strings.xml file. The xml file contains following code: <string name="credit_card_title">Card Type</string> <string-array name="credit_card"> <item >Select</item> <item >Visa</item> <item >MC</item> <item >Amex</item> <item >Discover</item> my spinner code is: <Spinner android:id="@+id/crdtcrd_crdtype" android:layout_width="match_parent" android:layout_height="wrap_content" android:entries="@array/credit_card" android:prompt="@string/credit_card_title" /> After retriving the value from the json url I am storing it in variable name String cardtype Now how can I display the value of cardtype in the Spinner crtdcrd_crdtype.... the json url is: http://mygogolfteetime.com/iphone/login/[email protected]/123456 From this URL I have to retrieve the value of cardtype and after retrieving the value i have to display it in the spinner.. There are different values for cardype like visa, mc, amex and discover All these values are in my strings.xml file and after retrieving the value I have to display it in Spinner.. Help needed still not able to find the solution.. Thanks in advance...

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  • JSON is not being recognised

    - by richzilla
    Hi All, Im having a bit of trouble getting my JSON to be recognised by my web page. I have validated JSON that im getting returned from server, so i know that is correct, however my javascript function is not doing anything with it. My succes function is as follows: success: function(data) { $('input[name=customer_name]').val(data.name); $('textarea[name=customer_address]').text(data.address); $('input[name=customer_email]').val(data.email); $('input[name=customer_tel]').val(data.tel); $('input[name=user_id]').val(item.id); } Yet the fields are not being repopulated with the data that is returned, if it helps, a sample of my JSON data: { "name": "Terry O'Toole", "address": "Terrys House\nTerry Street\nTerrysville\nTerrytown\nTT1 6TT", "email": "[email protected]", "tel": "05110000000" } Any help would be appreciated. [EDIT] Expanded ajax call: $.ajax({ url: "<?php echo site_url('user/users/ajax'); ?>", type: 'POST', data: {"userid": item.id}, success: function(data) { $('input[name=customer_name]').val(data.name); $('textarea[name=customer_address]').text(data.address); $('input[name=customer_email]').val(data.email); $('input[name=customer_tel]').val(data.tel); $('input[name=user_id]').val(item.id); } }) });

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  • JSON to javaScript array

    - by saturn_research
    I'm having a problem handling JSON data within JavaScript, specifically in regards to using the data as an array and accessing and iterating through individual values. The JSON file is structured as follows: { "head": { "vars": [ "place" , "lat" , "long" , "page" ] } , "results": { "bindings": [ { "place": { "type": "literal" , "value": "Building A" } , "lat": { "datatype": "http://www.w3.org/2001/XMLSchema#float" , "type": "typed-literal" , "value": "10.3456" } , "long": { "datatype": "http://www.w3.org/2001/XMLSchema#float" , "type": "typed-literal" , "value": "-1.2345" } , "page": { "type": "uri" , "value": "http://www.example.com/a.html" } } , { "place": { "type": "literal" , "value": "Building B" } , "lat": { "datatype": "http://www.w3.org/2001/XMLSchema#float" , "type": "typed-literal" , "value": "11.3456" } , "long": { "datatype": "http://www.w3.org/2001/XMLSchema#float" , "type": "typed-literal" , "value": "-2.2345" } , "page": { "type": "uri" , "value": "http://www.example.com/b.html" } } , { "place": { "type": "literal" , "value": "Building C" } , "lat": { "datatype": "http://www.w3.org/2001/XMLSchema#float" , "type": "typed-literal" , "value": "12.3456" } , "long": { "datatype": "http://www.w3.org/2001/XMLSchema#float" , "type": "typed-literal" , "value": "-3.2345" } , "page": { "type": "uri" , "value": "http://www.example.com/c.html" } } ] } } I want to be able to convert this into a JavaScript array as follows in order that I can iterate through it and pull out the values for each location in order: var locations = [ ['Building A',10.3456,-1.2345,'http://www.example.com/a.html'], ['Building B',11.3456,-2.2345,'http://www.example.com/b.html'], ['Building C',12.3456,-3.2345,'http://www.example.com/c.html'] ]; Does anyone have any advice on how to achieve this? I have tried the following, but it picks up the "type" within the JSON, rather than just the value: $.each(JSONObject.results.bindings, function(i, object) { $.each(object, function(property, object) { $.each(object, function(property, value) { value; }); }); }); Any help, suggestions, advice or corrections would be greatly appreciated.

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  • JSON datas not loaded into content page

    - by Chelseawillrecover
    I am trying to append my JSON datas into the content page but the datas are not loaded. When I use console.log I can see the data appearing. JS: $(document).on('pagebeforeshow', '#blogposts', function() { //$.mobile.showPageLoadingMsg(); $.ajax({ url: "http://howtodeployit.com/category/daily-devotion/?json=recentstories&callback=", dataType: "json", jsonpCallback: 'successCallback', async: true, beforeSend: function() { $.mobile.showPageLoadingMsg(true); }, complete: function() { $.mobile.hidePageLoadingMsg(); }, success:function(data){ $.each(data.posts, function(i, val) { console.log(val.title); $('<li/>').append([$("<h3>", {html: val.title}),$("<p>", {html: val.excerpt})]).wrapInner('<a href="#devotionpost" onclick="showPost(' + val.id + ')"></a>').appendTo('#postList'); return (i !== 4); console.log('#postlist'); }); }, error: function(data) { alert("Data not found"); } }); }); HTML: <!-- Page: Blog Posts --> <div id="blogposts" data-role="page"> <div data-role="header" data-position="fixed"> <h2>My Blog Posts</h2> </div><!-- header --> <div data-role="content"> <ul id="postlist"> </ul><!-- content --> </div> <div class="load-more">Load More Posts...</div> </div><!-- page -->

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  • Iterate Through JSON Data for Specific Element - Similar to XPath

    - by Highroller
    I am working on an embedded system and my theory of the overall process follows this methodology: 1. Send a command to the back end asking for account information in JSON format. 2. The back end writes a JSON file with all accounts and associated information (there could be 0 to 16 accounts). 3. Here's where I get stuck - use JavaScript (we are using the JQuery library) to iterate through the returned information for a specific element (similar to XPath) and build an array based on the number of elements found to populate a drop-down box to select the account you want to view and then do stuff with the account info. So my code looks like this: loadAccounts = function() { $.getJSON('/info?q=voip.accounts[]', function(result) { var sipAcnts = $("#sipacnts"); $(sipAcnts).empty(); // empty the dropdown (if necessarry) // Get the 'label' element and stick it in an array // build the array and append it to the sipAcnts dropdown // use array index to ref the accounts info and do stuff with it } So what I need is the JSON version of XPath to build the array of voip.accounts.label. The first account info looks something like this: { "result_set": { "voip.accounts[0]": { "label": "Dispatch1", "enabled": true, "user": "1234", "name": "Jane Doe", "type": "sip", "sip": { "lots and lots of stuff": }, } } } Am I over complicating the issue? Any wisdom anyone could thrown down would be greatly appreciated.

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  • Java servlet's request parameter's name set to entire json object

    - by Geren White
    I'm sending a json object through ajax to a java servlet. The json object is key-value type with three keys that point to arrays and a key that points to a single string. I build it in javascript like this: var jsonObject = {"arrayOne": arrayOne, "arrayTwo": arrayTwo, "arrayThree": arrThree, "string": stringVar}; I then send it to a java servlet using ajax as follows: httpRequest.open('POST', url, true); httpRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); httpRequest.setRequestHeader("Connection", "close"); var jsonString = jsonObject.toJSONString(); httpRequest.send(jsonString); This will send the string to my servlet, but It isn't showing as I expect it to. The whole json string gets set to the name of one of my request's parameters. So in my servlet if I do request.getParameterNames(); It will return an enumeration with one of the table entries' key's to be the entire object contents. I may be mistaken, but my thought was that it should set each key to a different parameter name. So I should have 4 parameters, arrayOne, arrayTwo, arrayThree, and string. Am I doing something wrong or is my thinking off here? Any help is appreciated. Thanks

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  • JSON to display text -- Freezes UI

    - by Adam Storr
    Hi everyone, I currently have a very simple view which displays info from a JSON feed. The problem I'm facing is the few second pause I encounter once I press this tab. How can I make this view load instantly and then have the label.text areas load after? Preferable with an activity indicator? Should I use threads? Thanks in advance! Code: - (NSString *)stringWithUrl:(NSURL *)url { NSURLRequest *urlRequest = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestReloadRevalidatingCacheData timeoutInterval:30]; NSData *urlData; NSURLResponse *response; NSError *error; urlData = [NSURLConnection sendSynchronousRequest:urlRequest returningResponse:&response error:&error]; return [[NSString alloc] initWithData:urlData encoding:NSUTF8StringEncoding]; } - (id)objectWithUrl:(NSURL *)url { SBJsonParser *jsonParser = [SBJsonParser new]; NSString *jsonString = [self stringWithUrl:url]; return [jsonParser objectWithString:jsonString error:NULL]; } - (NSDictionary *)downloadStats { id response = [self objectWithUrl:[NSURL URLWithString:@"http://www.example.com/JSON"]]; NSDictionary *feed = (NSDictionary *)response; return feed; [feed release]; } - (void)viewDidLoad { [super viewDidLoad]; [GlobalStatsScrollView setScrollEnabled:YES]; [GlobalStatsScrollView setContentSize:CGSizeMake(320, 360)]; } - (void)viewWillAppear:(BOOL)animated { NSLog(@"View appears"); // Download JSON Feed NSDictionary *feed = [self downloadStats]; totalproduced.text = [feed valueForKey:@"Produced"]; totalno.text = [feed valueForKey:@"Total"]; mostcommon.text = [feed valueForKey:@"Most Common"]; }

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  • Convert JSON into array dataType

    - by Myhome Stories
    I have the following JSON string var json = {"result":[{"address":" Ardenham Court, Oxford Road ,AYLESBURY, BUCKINGHAMSHIRE ,UNITED KINGDOM","picture":"1.jpg","uniqueid":"8b54275a60088547d473d462763b4738","story":"I love my home. I feel safe, I am comfortable and I am loved. A home can't be a home without our parents and our loved ones. But sad to say, some are experiencing that eventhough their loved ones are in their houses, they are not loving each other. There is a big war. You can't call it a home."}]} I want to get address ,picture,story separately for accomplish this. I tried recent answers in stackoverflow, but I was not able to achieve it. Below is what I have tried, $.each(json.result.address, function (index, value) { // Get the items var items = this.address; // Here 'this' points to a 'group' in 'groups' // Iterate through items. $.each(items, function () { console.log(this.text); // Here 'this' points to an 'item' in 'items' }); });

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  • Not getting an array as result (calling a webservice by AJAX-JSON)

    - by Pasargad
    I'm trying to get the result of my web service as an array and then loop over the result to fetch all of the data; what I have done so far: In my web service when I return the result I use return json_encode($newFiles); and the result is as following: "[{\"path\":\"c:\\\\my_images\\\\123.jpg\",\"ID\":\"123\",\"FName\":\"John\",\"LName\":\"Brown\",\"dept\":\"Hr\"}]" tehn in my Web application I'm calling the rest web service by the following code in the RestService class: public function getNewImages($time) { $url = $this->rest_url['MyService'] . "?action=getAllNewPhotos&accessKey=" . $this->rest_key['MyService'] . "&lastcheck=" . $time; $ch = curl_init(); curl_setopt($ch, CURLOPT_URL, $url); curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); $data = curl_exec($ch); if ($data) { return json_decode($data); } else { return null; } } and then in my controller I have the following code: public function getNewImgs($time="2011-11-03 14:35:08") { $newImgs = $this->restservice->getNewImages($time); echo json_encode$newImgs; } and I'm calling this `enter code here`controller method by AJAX: $("#searchNewImgManually").click(function(e) { e.preventDefault(); $.ajax({ type: "POST", async: true, datatype: "json", url: "<?PHP echo base_url("myProjectController/getNewImgs"); ?>", success: function(imgsResults) { alert(imgsResults[0]); } }); }); but instead of giving me the first object it is just giving me quotation mark (the first charachter of the result) " Why is that? I'm passing in JSON format and in AJAX I mentioned datatype as "JSON" ! Please let me know if you need more clarification! Thanks :)

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  • .NET WebRequest.PreAuthenticate not quite what it sounds like

    - by Rick Strahl
    I’ve run into the  problem a few times now: How to pre-authenticate .NET WebRequest calls doing an HTTP call to the server – essentially send authentication credentials on the very first request instead of waiting for a server challenge first? At first glance this sound like it should be easy: The .NET WebRequest object has a PreAuthenticate property which sounds like it should force authentication credentials to be sent on the first request. Looking at the MSDN example certainly looks like it does: http://msdn.microsoft.com/en-us/library/system.net.webrequest.preauthenticate.aspx Unfortunately the MSDN sample is wrong. As is the text of the Help topic which incorrectly leads you to believe that PreAuthenticate… wait for it - pre-authenticates. But it doesn’t allow you to set credentials that are sent on the first request. What this property actually does is quite different. It doesn’t send credentials on the first request but rather caches the credentials ONCE you have already authenticated once. Http Authentication is based on a challenge response mechanism typically where the client sends a request and the server responds with a 401 header requesting authentication. So the client sends a request like this: GET /wconnect/admin/wc.wc?_maintain~ShowStatus HTTP/1.1 Host: rasnote User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506) Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en,de;q=0.7,en-us;q=0.3 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 300 Connection: keep-alive and the server responds with: HTTP/1.1 401 Unauthorized Cache-Control: private Content-Type: text/html; charset=utf-8 Server: Microsoft-IIS/7.5 WWW-Authenticate: basic realm=rasnote" X-AspNet-Version: 2.0.50727 WWW-Authenticate: Negotiate WWW-Authenticate: NTLM WWW-Authenticate: Basic realm="rasnote" X-Powered-By: ASP.NET Date: Tue, 27 Oct 2009 00:58:20 GMT Content-Length: 5163 plus the actual error message body. The client then is responsible for re-sending the current request with the authentication token information provided (in this case Basic Auth): GET /wconnect/admin/wc.wc?_maintain~ShowStatus HTTP/1.1 Host: rasnote User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506) Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en,de;q=0.7,en-us;q=0.3 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 300 Connection: keep-alive Cookie: TimeTrakker=2HJ1998WH06696; WebLogCommentUser=Rick Strahl|http://www.west-wind.com/|[email protected]; WebStoreUser=b8bd0ed9 Authorization: Basic cgsf12aDpkc2ZhZG1zMA== Once the authorization info is sent the server responds with the actual page result. Now if you use WebRequest (or WebClient) the default behavior is to re-authenticate on every request that requires authorization. This means if you look in  Fiddler or some other HTTP client Proxy that captures requests you’ll see that each request re-authenticates: Here are two requests fired back to back: and you can see the 401 challenge, the 200 response for both requests. If you watch this same conversation between a browser and a server you’ll notice that the first 401 is also there but the subsequent 401 requests are not present. WebRequest.PreAuthenticate And this is precisely what the WebRequest.PreAuthenticate property does: It’s a caching mechanism that caches the connection credentials for a given domain in the active process and resends it on subsequent requests. It does not send credentials on the first request but it will cache credentials on subsequent requests after authentication has succeeded: string url = "http://rasnote/wconnect/admin/wc.wc?_maintain~ShowStatus"; HttpWebRequest req = HttpWebRequest.Create(url) as HttpWebRequest; req.PreAuthenticate = true; req.Credentials = new NetworkCredential("rick", "secret", "rasnote"); req.AuthenticationLevel = System.Net.Security.AuthenticationLevel.MutualAuthRequested; req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; WebResponse resp = req.GetResponse(); resp.Close(); req = HttpWebRequest.Create(url) as HttpWebRequest; req.PreAuthenticate = true; req.Credentials = new NetworkCredential("rstrahl", "secret", "rasnote"); req.AuthenticationLevel = System.Net.Security.AuthenticationLevel.MutualAuthRequested; req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; resp = req.GetResponse(); which results in the desired sequence: where only the first request doesn’t send credentials. This is quite useful as it saves quite a few round trips to the server – bascially it saves one auth request request for every authenticated request you make. In most scenarios I think you’d want to send these credentials this way but one downside to this is that there’s no way to log out the client. Since the client always sends the credentials once authenticated only an explicit operation ON THE SERVER can undo the credentials by forcing another login explicitly (ie. re-challenging with a forced 401 request). Forcing Basic Authentication Credentials on the first Request On a few occasions I’ve needed to send credentials on a first request – mainly to some oddball third party Web Services (why you’d want to use Basic Auth on a Web Service is beyond me – don’t ask but it’s not uncommon in my experience). This is true of certain services that are using Basic Authentication (especially some Apache based Web Services) and REQUIRE that the authentication is sent right from the first request. No challenge first. Ugly but there it is. Now the following works only with Basic Authentication because it’s pretty straight forward to create the Basic Authorization ‘token’ in code since it’s just an unencrypted encoding of the user name and password into base64. As you might guess this is totally unsecure and should only be used when using HTTPS/SSL connections (i’m not in this example so I can capture the Fiddler trace and my local machine doesn’t have a cert installed, but for production apps ALWAYS use SSL with basic auth). The idea is that you simply add the required Authorization header to the request on your own along with the authorization string that encodes the username and password: string url = "http://rasnote/wconnect/admin/wc.wc?_maintain~ShowStatus"; HttpWebRequest req = HttpWebRequest.Create(url) as HttpWebRequest; string user = "rick"; string pwd = "secret"; string domain = "www.west-wind.com"; string auth = "Basic " + Convert.ToBase64String(System.Text.Encoding.Default.GetBytes(user + ":" + pwd)); req.PreAuthenticate = true; req.AuthenticationLevel = System.Net.Security.AuthenticationLevel.MutualAuthRequested;req.Headers.Add("Authorization", auth); req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; WebResponse resp = req.GetResponse(); resp.Close(); This works and causes the request to immediately send auth information to the server. However, this only works with Basic Auth because you can actually create the authentication credentials easily on the client because it’s essentially clear text. The same doesn’t work for Windows or Digest authentication since you can’t easily create the authentication token on the client and send it to the server. Another issue with this approach is that PreAuthenticate has no effect when you manually force the authentication. As far as Web Request is concerned it never sent the authentication information so it’s not actually caching the value any longer. If you run 3 requests in a row like this: string url = "http://rasnote/wconnect/admin/wc.wc?_maintain~ShowStatus"; HttpWebRequest req = HttpWebRequest.Create(url) as HttpWebRequest; string user = "ricks"; string pwd = "secret"; string domain = "www.west-wind.com"; string auth = "Basic " + Convert.ToBase64String(System.Text.Encoding.Default.GetBytes(user + ":" + pwd)); req.PreAuthenticate = true; req.Headers.Add("Authorization", auth); req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; WebResponse resp = req.GetResponse(); resp.Close(); req = HttpWebRequest.Create(url) as HttpWebRequest; req.PreAuthenticate = true; req.Credentials = new NetworkCredential(user, pwd, domain); req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; resp = req.GetResponse(); resp.Close(); req = HttpWebRequest.Create(url) as HttpWebRequest; req.PreAuthenticate = true; req.Credentials = new NetworkCredential(user, pwd, domain); req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; resp = req.GetResponse(); you’ll find the trace looking like this: where the first request (the one we explicitly add the header to) authenticates, the second challenges, and any subsequent ones then use the PreAuthenticate credential caching. In effect you’ll end up with one extra 401 request in this scenario, which is still better than 401 challenges on each request. Getting Access to WebRequest in Classic .NET Web Service Clients If you’re running a classic .NET Web Service client (non-WCF) one issue with the above is how do you get access to the WebRequest to actually add the custom headers to do the custom Authentication described above? One easy way is to implement a partial class that allows you add headers with something like this: public partial class TaxService { protected NameValueCollection Headers = new NameValueCollection(); public void AddHttpHeader(string key, string value) { this.Headers.Add(key,value); } public void ClearHttpHeaders() { this.Headers.Clear(); } protected override WebRequest GetWebRequest(Uri uri) { HttpWebRequest request = (HttpWebRequest) base.GetWebRequest(uri); request.Headers.Add(this.Headers); return request; } } where TaxService is the name of the .NET generated proxy class. In code you can then call AddHttpHeader() anywhere to add additional headers which are sent as part of the GetWebRequest override. Nice and simple once you know where to hook it. For WCF there’s a bit more work involved by creating a message extension as described here: http://weblogs.asp.net/avnerk/archive/2006/04/26/Adding-custom-headers-to-every-WCF-call-_2D00_-a-solution.aspx. FWIW, I think that HTTP header manipulation should be readily available on any HTTP based Web Service client DIRECTLY without having to subclass or implement a special interface hook. But alas a little extra work is required in .NET to make this happen Not a Common Problem, but when it happens… This has been one of those issues that is really rare, but it’s bitten me on several occasions when dealing with oddball Web services – a couple of times in my own work interacting with various Web Services and a few times on customer projects that required interaction with credentials-first services. Since the servers determine the protocol, we don’t have a choice but to follow the protocol. Lovely following standards that implementers decide to ignore, isn’t it? :-}© Rick Strahl, West Wind Technologies, 2005-2010Posted in .NET  CSharp  Web Services  

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  • Host AngularJS (Html5Mode) in ASP.NET vNext

    - by Shaun
    Originally posted on: http://geekswithblogs.net/shaunxu/archive/2014/06/10/host-angularjs-html5mode-in-asp.net-vnext.aspxMicrosoft had announced ASP.NET vNext in BUILD and TechED recently and as a developer, I found that we can add features into one ASP.NET vNext application such as MVC, WebAPI, SignalR, etc.. Also it's cross platform which means I can host ASP.NET on Windows, Linux and OS X.   If you are following my blog you should knew that I'm currently working on a project which uses ASP.NET WebAPI, SignalR and AngularJS. Currently the AngularJS part is hosted by Express in Node.js while WebAPI and SignalR are hosted in ASP.NET. I was looking for a solution to host all of them in one platform so that my SignalR can utilize WebSocket. Currently AngularJS and SignalR are hosted in the same domain but different port so it has to use ServerSendEvent. It can be upgraded to WebSocket if I host both of them in the same port.   Host AngularJS in ASP.NET vNext Static File Middleware ASP.NET vNext utilizes middleware pattern to register feature it uses, which is very similar as Express in Node.js. Since AngularJS is a pure client side framework in theory what I need to do is to use ASP.NET vNext as a static file server. This is very easy as there's a build-in middleware shipped alone with ASP.NET vNext. Assuming I have "index.html" as below. 1: <html data-ng-app="demo"> 2: <head> 3: <script type="text/javascript" src="angular.js" /> 4: <script type="text/javascript" src="angular-ui-router.js" /> 5: <script type="text/javascript" src="app.js" /> 6: </head> 7: <body> 8: <h1>ASP.NET vNext with AngularJS</h1> 9: <div> 10: <a href="javascript:void(0)" data-ui-sref="view1">View 1</a> | 11: <a href="javascript:void(0)" data-ui-sref="view2">View 2</a> 12: </div> 13: <div data-ui-view></div> 14: </body> 15: </html> And the AngularJS JavaScript file as below. Notices that I have two views which only contains one line literal indicates the view name. 1: 'use strict'; 2:  3: var app = angular.module('demo', ['ui.router']); 4:  5: app.config(['$stateProvider', '$locationProvider', function ($stateProvider, $locationProvider) { 6: $stateProvider.state('view1', { 7: url: '/view1', 8: templateUrl: 'view1.html', 9: controller: 'View1Ctrl' }); 10:  11: $stateProvider.state('view2', { 12: url: '/view2', 13: templateUrl: 'view2.html', 14: controller: 'View2Ctrl' }); 15: }]); 16:  17: app.controller('View1Ctrl', function ($scope) { 18: }); 19:  20: app.controller('View2Ctrl', function ($scope) { 21: }); All AngularJS files are located in "app" folder and my ASP.NET vNext files are besides it. The "project.json" contains all dependencies I need to host static file server. 1: { 2: "dependencies": { 3: "Helios" : "0.1-alpha-*", 4: "Microsoft.AspNet.FileSystems": "0.1-alpha-*", 5: "Microsoft.AspNet.Http": "0.1-alpha-*", 6: "Microsoft.AspNet.StaticFiles": "0.1-alpha-*", 7: "Microsoft.AspNet.Hosting": "0.1-alpha-*", 8: "Microsoft.AspNet.Server.WebListener": "0.1-alpha-*" 9: }, 10: "commands": { 11: "web": "Microsoft.AspNet.Hosting server=Microsoft.AspNet.Server.WebListener server.urls=http://localhost:22222" 12: }, 13: "configurations" : { 14: "net45" : { 15: }, 16: "k10" : { 17: "System.Diagnostics.Contracts": "4.0.0.0", 18: "System.Security.Claims" : "0.1-alpha-*" 19: } 20: } 21: } Below is "Startup.cs" which is the entry file of my ASP.NET vNext. What I need to do is to let my application use FileServerMiddleware. 1: using System; 2: using Microsoft.AspNet.Builder; 3: using Microsoft.AspNet.FileSystems; 4: using Microsoft.AspNet.StaticFiles; 5:  6: namespace Shaun.AspNet.Plugins.AngularServer.Demo 7: { 8: public class Startup 9: { 10: public void Configure(IBuilder app) 11: { 12: app.UseFileServer(new FileServerOptions() { 13: EnableDirectoryBrowsing = true, 14: FileSystem = new PhysicalFileSystem(System.IO.Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "app")) 15: }); 16: } 17: } 18: } Next, I need to create "NuGet.Config" file in the PARENT folder so that when I run "kpm restore" command later it can find ASP.NET vNext NuGet package successfully. 1: <?xml version="1.0" encoding="utf-8"?> 2: <configuration> 3: <packageSources> 4: <add key="AspNetVNext" value="https://www.myget.org/F/aspnetvnext/api/v2" /> 5: <add key="NuGet.org" value="https://nuget.org/api/v2/" /> 6: </packageSources> 7: <packageSourceCredentials> 8: <AspNetVNext> 9: <add key="Username" value="aspnetreadonly" /> 10: <add key="ClearTextPassword" value="4d8a2d9c-7b80-4162-9978-47e918c9658c" /> 11: </AspNetVNext> 12: </packageSourceCredentials> 13: </configuration> Now I need to run "kpm restore" to resolve all dependencies of my application. Finally, use "k web" to start the application which will be a static file server on "app" sub folder in the local 22222 port.   Support AngularJS Html5Mode AngularJS works well in previous demo. But you will note that there is a "#" in the browser address. This is because by default AngularJS adds "#" next to its entry page so ensure all request will be handled by this entry page. For example, in this case my entry page is "index.html", so when I clicked "View 1" in the page the address will be changed to "/#/view1" which means it still tell the web server I'm still looking for "index.html". This works, but makes the address looks ugly. Hence AngularJS introduces a feature called Html5Mode, which will get rid off the annoying "#" from the address bar. Below is the "app.js" with Html5Mode enabled, just one line of code. 1: 'use strict'; 2:  3: var app = angular.module('demo', ['ui.router']); 4:  5: app.config(['$stateProvider', '$locationProvider', function ($stateProvider, $locationProvider) { 6: $stateProvider.state('view1', { 7: url: '/view1', 8: templateUrl: 'view1.html', 9: controller: 'View1Ctrl' }); 10:  11: $stateProvider.state('view2', { 12: url: '/view2', 13: templateUrl: 'view2.html', 14: controller: 'View2Ctrl' }); 15:  16: // enable html5mode 17: $locationProvider.html5Mode(true); 18: }]); 19:  20: app.controller('View1Ctrl', function ($scope) { 21: }); 22:  23: app.controller('View2Ctrl', function ($scope) { 24: }); Then let's went to the root path of our website and click "View 1" you will see there's no "#" in the address. But the problem is, if we hit F5 the browser will be turn to blank. This is because in this mode the browser told the web server I want static file named "view1" but there's no file on the server. So underlying our web server, which is built by ASP.NET vNext, responded 404. To fix this problem we need to create our own ASP.NET vNext middleware. What it needs to do is firstly try to respond the static file request with the default StaticFileMiddleware. If the response status code was 404 then change the request path value to the entry page and try again. 1: public class AngularServerMiddleware 2: { 3: private readonly AngularServerOptions _options; 4: private readonly RequestDelegate _next; 5: private readonly StaticFileMiddleware _innerMiddleware; 6:  7: public AngularServerMiddleware(RequestDelegate next, AngularServerOptions options) 8: { 9: _next = next; 10: _options = options; 11:  12: _innerMiddleware = new StaticFileMiddleware(next, options.FileServerOptions.StaticFileOptions); 13: } 14:  15: public async Task Invoke(HttpContext context) 16: { 17: // try to resolve the request with default static file middleware 18: await _innerMiddleware.Invoke(context); 19: Console.WriteLine(context.Request.Path + ": " + context.Response.StatusCode); 20: // route to root path if the status code is 404 21: // and need support angular html5mode 22: if (context.Response.StatusCode == 404 && _options.Html5Mode) 23: { 24: context.Request.Path = _options.EntryPath; 25: await _innerMiddleware.Invoke(context); 26: Console.WriteLine(">> " + context.Request.Path + ": " + context.Response.StatusCode); 27: } 28: } 29: } We need an option class where user can specify the host root path and the entry page path. 1: public class AngularServerOptions 2: { 3: public FileServerOptions FileServerOptions { get; set; } 4:  5: public PathString EntryPath { get; set; } 6:  7: public bool Html5Mode 8: { 9: get 10: { 11: return EntryPath.HasValue; 12: } 13: } 14:  15: public AngularServerOptions() 16: { 17: FileServerOptions = new FileServerOptions(); 18: EntryPath = PathString.Empty; 19: } 20: } We also need an extension method so that user can append this feature in "Startup.cs" easily. 1: public static class AngularServerExtension 2: { 3: public static IBuilder UseAngularServer(this IBuilder builder, string rootPath, string entryPath) 4: { 5: var options = new AngularServerOptions() 6: { 7: FileServerOptions = new FileServerOptions() 8: { 9: EnableDirectoryBrowsing = false, 10: FileSystem = new PhysicalFileSystem(System.IO.Path.Combine(AppDomain.CurrentDomain.BaseDirectory, rootPath)) 11: }, 12: EntryPath = new PathString(entryPath) 13: }; 14:  15: builder.UseDefaultFiles(options.FileServerOptions.DefaultFilesOptions); 16:  17: return builder.Use(next => new AngularServerMiddleware(next, options).Invoke); 18: } 19: } Now with these classes ready we will change our "Startup.cs", use this middleware replace the default one, tell the server try to load "index.html" file if it cannot find resource. The code below is just for demo purpose. I just tried to load "index.html" in all cases once the StaticFileMiddleware returned 404. In fact we need to validation to make sure this is an AngularJS route request instead of a normal static file request. 1: using System; 2: using Microsoft.AspNet.Builder; 3: using Microsoft.AspNet.FileSystems; 4: using Microsoft.AspNet.StaticFiles; 5: using Shaun.AspNet.Plugins.AngularServer; 6:  7: namespace Shaun.AspNet.Plugins.AngularServer.Demo 8: { 9: public class Startup 10: { 11: public void Configure(IBuilder app) 12: { 13: app.UseAngularServer("app", "/index.html"); 14: } 15: } 16: } Now let's run "k web" again and try to refresh our browser and we can see the page loaded successfully. In the console window we can find the original request got 404 and we try to find "index.html" and return the correct result.   Summary In this post I introduced how to use ASP.NET vNext to host AngularJS application as a static file server. I also demonstrated how to extend ASP.NET vNext, so that it supports AngularJS Html5Mode. You can download the source code here.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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  • Announcing Entity Framework Code-First (CTP5 release)

    - by ScottGu
    This week the data team released the CTP5 build of the new Entity Framework Code-First library.  EF Code-First enables a pretty sweet code-centric development workflow for working with data.  It enables you to: Develop without ever having to open a designer or define an XML mapping file Define model objects by simply writing “plain old classes” with no base classes required Use a “convention over configuration” approach that enables database persistence without explicitly configuring anything Optionally override the convention-based persistence and use a fluent code API to fully customize the persistence mapping I’m a big fan of the EF Code-First approach, and wrote several blog posts about it this summer: Code-First Development with Entity Framework 4 (July 16th) EF Code-First: Custom Database Schema Mapping (July 23rd) Using EF Code-First with an Existing Database (August 3rd) Today’s new CTP5 release delivers several nice improvements over the CTP4 build, and will be the last preview build of Code First before the final release of it.  We will ship the final EF Code First release in the first quarter of next year (Q1 of 2011).  It works with all .NET application types (including both ASP.NET Web Forms and ASP.NET MVC projects). Installing EF Code First You can install and use EF Code First CTP5 using one of two ways: Approach 1) By downloading and running a setup program.  Once installed you can reference the EntityFramework.dll assembly it provides within your projects.      or: Approach 2) By using the NuGet Package Manager within Visual Studio to download and install EF Code First within a project.  To do this, simply bring up the NuGet Package Manager Console within Visual Studio (View->Other Windows->Package Manager Console) and type “Install-Package EFCodeFirst”: Typing “Install-Package EFCodeFirst” within the Package Manager Console will cause NuGet to download the EF Code First package, and add it to your current project: Doing this will automatically add a reference to the EntityFramework.dll assembly to your project:   NuGet enables you to have EF Code First setup and ready to use within seconds.  When the final release of EF Code First ships you’ll also be able to just type “Update-Package EFCodeFirst” to update your existing projects to use the final release. EF Code First Assembly and Namespace The CTP5 release of EF Code First has an updated assembly name, and new .NET namespace: Assembly Name: EntityFramework.dll Namespace: System.Data.Entity These names match what we plan to use for the final release of the library. Nice New CTP5 Improvements The new CTP5 release of EF Code First contains a bunch of nice improvements and refinements. Some of the highlights include: Better support for Existing Databases Built-in Model-Level Validation and DataAnnotation Support Fluent API Improvements Pluggable Conventions Support New Change Tracking API Improved Concurrency Conflict Resolution Raw SQL Query/Command Support The rest of this blog post contains some more details about a few of the above changes. Better Support for Existing Databases EF Code First makes it really easy to create model layers that work against existing databases.  CTP5 includes some refinements that further streamline the developer workflow for this scenario. Below are the steps to use EF Code First to create a model layer for the Northwind sample database: Step 1: Create Model Classes and a DbContext class Below is all of the code necessary to implement a simple model layer using EF Code First that goes against the Northwind database: EF Code First enables you to use “POCO” – Plain Old CLR Objects – to represent entities within a database.  This means that you do not need to derive model classes from a base class, nor implement any interfaces or data persistence attributes on them.  This enables the model classes to be kept clean, easily testable, and “persistence ignorant”.  The Product and Category classes above are examples of POCO model classes. EF Code First enables you to easily connect your POCO model classes to a database by creating a “DbContext” class that exposes public properties that map to the tables within a database.  The Northwind class above illustrates how this can be done.  It is mapping our Product and Category classes to the “Products” and “Categories” tables within the database.  The properties within the Product and Category classes in turn map to the columns within the Products and Categories tables – and each instance of a Product/Category object maps to a row within the tables. The above code is all of the code required to create our model and data access layer!  Previous CTPs of EF Code First required an additional step to work against existing databases (a call to Database.Initializer<Northwind>(null) to tell EF Code First to not create the database) – this step is no longer required with the CTP5 release.  Step 2: Configure the Database Connection String We’ve written all of the code we need to write to define our model layer.  Our last step before we use it will be to setup a connection-string that connects it with our database.  To do this we’ll add a “Northwind” connection-string to our web.config file (or App.Config for client apps) like so:   <connectionStrings>          <add name="Northwind"          connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\northwind.mdf;User Instance=true"          providerName="System.Data.SqlClient" />   </connectionStrings> EF “code first” uses a convention where DbContext classes by default look for a connection-string that has the same name as the context class.  Because our DbContext class is called “Northwind” it by default looks for a “Northwind” connection-string to use.  Above our Northwind connection-string is configured to use a local SQL Express database (stored within the \App_Data directory of our project).  You can alternatively point it at a remote SQL Server. Step 3: Using our Northwind Model Layer We can now easily query and update our database using the strongly-typed model layer we just built with EF Code First. The code example below demonstrates how to use LINQ to query for products within a specific product category.  This query returns back a sequence of strongly-typed Product objects that match the search criteria: The code example below demonstrates how we can retrieve a specific Product object, update two of its properties, and then save the changes back to the database: EF Code First handles all of the change-tracking and data persistence work for us, and allows us to focus on our application and business logic as opposed to having to worry about data access plumbing. Built-in Model Validation EF Code First allows you to use any validation approach you want when implementing business rules with your model layer.  This enables a great deal of flexibility and power. Starting with this week’s CTP5 release, EF Code First also now includes built-in support for both the DataAnnotation and IValidatorObject validation support built-into .NET 4.  This enables you to easily implement validation rules on your models, and have these rules automatically be enforced by EF Code First whenever you save your model layer.  It provides a very convenient “out of the box” way to enable validation within your applications. Applying DataAnnotations to our Northwind Model The code example below demonstrates how we could add some declarative validation rules to two of the properties of our “Product” model: We are using the [Required] and [Range] attributes above.  These validation attributes live within the System.ComponentModel.DataAnnotations namespace that is built-into .NET 4, and can be used independently of EF.  The error messages specified on them can either be explicitly defined (like above) – or retrieved from resource files (which makes localizing applications easy). Validation Enforcement on SaveChanges() EF Code-First (starting with CTP5) now automatically applies and enforces DataAnnotation rules when a model object is updated or saved.  You do not need to write any code to enforce this – this support is now enabled by default.  This new support means that the below code – which violates our above rules – will automatically throw an exception when we call the “SaveChanges()” method on our Northwind DbContext: The DbEntityValidationException that is raised when the SaveChanges() method is invoked contains a “EntityValidationErrors” property that you can use to retrieve the list of all validation errors that occurred when the model was trying to save.  This enables you to easily guide the user on how to fix them.  Note that EF Code-First will abort the entire transaction of changes if a validation rule is violated – ensuring that our database is always kept in a valid, consistent state. EF Code First’s validation enforcement works both for the built-in .NET DataAnnotation attributes (like Required, Range, RegularExpression, StringLength, etc), as well as for any custom validation rule you create by sub-classing the System.ComponentModel.DataAnnotations.ValidationAttribute base class. UI Validation Support A lot of our UI frameworks in .NET also provide support for DataAnnotation-based validation rules. For example, ASP.NET MVC, ASP.NET Dynamic Data, and Silverlight (via WCF RIA Services) all provide support for displaying client-side validation UI that honor the DataAnnotation rules applied to model objects. The screen-shot below demonstrates how using the default “Add-View” scaffold template within an ASP.NET MVC 3 application will cause appropriate validation error messages to be displayed if appropriate values are not provided: ASP.NET MVC 3 supports both client-side and server-side enforcement of these validation rules.  The error messages displayed are automatically picked up from the declarative validation attributes – eliminating the need for you to write any custom code to display them. Keeping things DRY The “DRY Principle” stands for “Do Not Repeat Yourself”, and is a best practice that recommends that you avoid duplicating logic/configuration/code in multiple places across your application, and instead specify it only once and have it apply everywhere. EF Code First CTP5 now enables you to apply declarative DataAnnotation validations on your model classes (and specify them only once) and then have the validation logic be enforced (and corresponding error messages displayed) across all applications scenarios – including within controllers, views, client-side scripts, and for any custom code that updates and manipulates model classes. This makes it much easier to build good applications with clean code, and to build applications that can rapidly iterate and evolve. Other EF Code First Improvements New to CTP5 EF Code First CTP5 includes a bunch of other improvements as well.  Below are a few short descriptions of some of them: Fluent API Improvements EF Code First allows you to override an “OnModelCreating()” method on the DbContext class to further refine/override the schema mapping rules used to map model classes to underlying database schema.  CTP5 includes some refinements to the ModelBuilder class that is passed to this method which can make defining mapping rules cleaner and more concise.  The ADO.NET Team blogged some samples of how to do this here. Pluggable Conventions Support EF Code First CTP5 provides new support that allows you to override the “default conventions” that EF Code First honors, and optionally replace them with your own set of conventions. New Change Tracking API EF Code First CTP5 exposes a new set of change tracking information that enables you to access Original, Current & Stored values, and State (e.g. Added, Unchanged, Modified, Deleted).  This support is useful in a variety of scenarios. Improved Concurrency Conflict Resolution EF Code First CTP5 provides better exception messages that allow access to the affected object instance and the ability to resolve conflicts using current, original and database values.  Raw SQL Query/Command Support EF Code First CTP5 now allows raw SQL queries and commands (including SPROCs) to be executed via the SqlQuery and SqlCommand methods exposed off of the DbContext.Database property.  The results of these method calls can be materialized into object instances that can be optionally change-tracked by the DbContext.  This is useful for a variety of advanced scenarios. Full Data Annotations Support EF Code First CTP5 now supports all standard DataAnnotations within .NET, and can use them both to perform validation as well as to automatically create the appropriate database schema when EF Code First is used in a database creation scenario.  Summary EF Code First provides an elegant and powerful way to work with data.  I really like it because it is extremely clean and supports best practices, while also enabling solutions to be implemented very, very rapidly.  The code-only approach of the library means that model layers end up being flexible and easy to customize. This week’s CTP5 release further refines EF Code First and helps ensure that it will be really sweet when it ships early next year.  I recommend using NuGet to install and give it a try today.  I think you’ll be pleasantly surprised by how awesome it is. Hope this helps, Scott

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  • How to create a new WCF/MVC/jQuery application from scratch

    - by pjohnson
    As a corporate developer by trade, I don't get much opportunity to create from-the-ground-up web sites; usually it's tweaks, fixes, and new functionality to existing sites. And with hobby sites, I often don't find the challenges I run into with enterprise systems; usually it's starting from Visual Studio's boilerplate project and adding whatever functionality I want to play around with, rarely deploying outside my own machine. So my experience creating a new enterprise-level site was a bit dated, and the technologies to do so have come a long way, and are much more ready to go out of the box. My intention with this post isn't so much to provide any groundbreaking insights, but to just tie together a lot of information in one place to make it easy to create a new site from scratch. Architecture One site I created earlier this year had an MVC 3 front end and a WCF 4-driven service layer. Using Visual Studio 2010, these project types are easy enough to add to a new solution. I created a third Class Library project to store common functionality the front end and services layers both needed to access, for example, the DataContract classes that the front end uses to call services in the service layer. By keeping DataContract classes in a separate project, I avoided the need for the front end to have an assembly/project reference directly to the services code, a bit cleaner and more flexible of an SOA implementation. Consuming the service Even by this point, VS has given you a lot. You have a working web site and a working service, neither of which do much but are great starting points. To wire up the front end and the services, I needed to create proxy classes and WCF client configuration information. I decided to use the SvcUtil.exe utility provided as part of the Windows SDK, which you should have installed if you installed VS. VS also provides an Add Service Reference command since the .NET 1.x ASMX days, which I've never really liked; it creates several .cs/.disco/etc. files, some of which contained hardcoded URL's, adding duplicate files (*1.cs, *2.cs, etc.) without doing a good job of cleaning up after itself. I've found SvcUtil much cleaner, as it outputs one C# file (containing several proxy classes) and a config file with settings, and it's easier to use to regenerate the proxy classes when the service changes, and to then maintain all your configuration in one place (your Web.config, instead of the Service Reference files). I provided it a reference to a copy of my common assembly so it doesn't try to recreate the data contract classes, had it use the type List<T> for collections, and modified the output files' names and .NET namespace, ending up with a command like: svcutil.exe /l:cs /o:MyService.cs /config:MyService.config /r:MySite.Common.dll /ct:System.Collections.Generic.List`1 /n:*,MySite.Web.ServiceProxies http://localhost:59999/MyService.svc I took the generated MyService.cs file and drop it in the web project, under a ServiceProxies folder, matching the namespace and keeping it separate from classes I coded manually. Integrating the config file took a little more work, but only needed to be done once as these settings didn't often change. A great thing Microsoft improved with WCF 4 is configuration; namely, you can use all the default settings and not have to specify them explicitly in your config file. Unfortunately, SvcUtil doesn't generate its config file this way. If you just copy & paste MyService.config's contents into your front end's Web.config, you'll copy a lot of settings you don't need, plus this will get unwieldy if you add more services in the future, each with its own custom binding. Really, as the only mandatory settings are the endpoint's ABC's (address, binding, and contract) you can get away with just this: <system.serviceModel>  <client>    <endpoint address="http://localhost:59999/MyService.svc" binding="wsHttpBinding" contract="MySite.Web.ServiceProxies.IMyService" />  </client></system.serviceModel> By default, the services project uses basicHttpBinding. As you can see, I switched it to wsHttpBinding, a more modern standard. Using something like netTcpBinding would probably be faster and more efficient since the client & service are both written in .NET, but it requires additional server setup and open ports, whereas switching to wsHttpBinding is much simpler. From an MVC controller action method, I instantiated the client, and invoked the method for my operation. As with any object that implements IDisposable, I wrapped it in C#'s using() statement, a tidy construct that ensures Dispose gets called no matter what, even if an exception occurs. Unfortunately there are problems with that, as WCF's ClientBase<TChannel> class doesn't implement Dispose according to Microsoft's own usage guidelines. I took an approach similar to Technology Toolbox's fix, except using partial classes instead of a wrapper class to extend the SvcUtil-generated proxy, making the fix more seamless from the controller's perspective, and theoretically, less code I have to change if and when Microsoft fixes this behavior. User interface The MVC 3 project template includes jQuery and some other common JavaScript libraries by default. I updated the ones I used to the latest versions using NuGet, available in VS via the Tools > Library Package Manager > Manage NuGet Packages for Solution... > Updates. I also used this dialog to remove packages I wasn't using. Given that it's smart enough to know the difference between the .js and .min.js files, I was hoping it would be smart enough to know which to include during build and publish operations, but this doesn't seem to be the case. I ended up using Cassette to perform the minification and bundling of my JavaScript and CSS files; ASP.NET 4.5 includes this functionality out of the box. The web client to web server link via jQuery was easy enough. In my JavaScript function, unobtrusively wired up to a button's click event, I called $.ajax, corresponding to an action method that returns a JsonResult, accomplished by passing my model class to the Controller.Json() method, which jQuery helpfully translates from JSON to a JavaScript object.$.ajax calls weren't perfectly straightforward. I tried using the simpler $.post method instead, but ran into trouble without specifying the contentType parameter, which $.post doesn't have. The url parameter is simple enough, though for flexibility in how the site is deployed, I used MVC's Url.Action method to get the URL, then sent this to JavaScript in a JavaScript string variable. If the request needed input data, I used the JSON.stringify function to convert a JavaScript object with the parameters into a JSON string, which MVC then parses into strongly-typed C# parameters. I also specified "json" for dataType, and "application/json; charset=utf-8" for contentType. For success and error, I provided my success and error handling functions, though success is a bit hairier. "Success" in this context indicates whether the HTTP request succeeds, not whether what you wanted the AJAX call to do on the web server was successful. For example, if you make an AJAX call to retrieve a piece of data, the success handler will be invoked for any 200 OK response, and the error handler will be invoked for failed requests, e.g. a 404 Not Found (if the server rejected the URL you provided in the url parameter) or 500 Internal Server Error (e.g. if your C# code threw an exception that wasn't caught). If an exception was caught and handled, or if the data requested wasn't found, this would likely go through the success handler, which would need to do further examination to verify it did in fact get back the data for which it asked. I discuss this more in the next section. Logging and exception handling At this point, I had a working application. If I ran into any errors or unexpected behavior, debugging was easy enough, but of course that's not an option on public web servers. Microsoft Enterprise Library 5.0 filled this gap nicely, with its Logging and Exception Handling functionality. First I installed Enterprise Library; NuGet as outlined above is probably the best way to do so. I needed a total of three assembly references--Microsoft.Practices.EnterpriseLibrary.ExceptionHandling, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.Logging, and Microsoft.Practices.EnterpriseLibrary.Logging. VS links with the handy Enterprise Library 5.0 Configuration Console, accessible by right-clicking your Web.config and choosing Edit Enterprise Library V5 Configuration. In this console, under Logging Settings, I set up a Rolling Flat File Trace Listener to write to log files but not let them get too large, using a Text Formatter with a simpler template than that provided by default. Logging to a different (or additional) destination is easy enough, but a flat file suited my needs. At this point, I verified it wrote as expected by calling the Microsoft.Practices.EnterpriseLibrary.Logging.Logger.Write method from my C# code. With those settings verified, I went on to wire up Exception Handling with Logging. Back in the EntLib Configuration Console, under Exception Handling, I used a LoggingExceptionHandler, setting its Logging Category to the category I already had configured in the Logging Settings. Then, from code (e.g. a controller's OnException method, or any action method's catch block), I called the Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.ExceptionPolicy.HandleException method, providing the exception and the exception policy name I had configured in the Exception Handling Settings. Before I got this configured correctly, when I tried it out, nothing was logged. In working with .NET, I'm used to seeing an exception if something doesn't work or isn't set up correctly, but instead working with these EntLib modules reminds me more of JavaScript (before the "use strict" v5 days)--it just does nothing and leaves you to figure out why, I presume due in part to the listener pattern Microsoft followed with the Enterprise Library. First, I verified logging worked on its own. Then, verifying/correcting where each piece wires up to the next resolved my problem. Your C# code calls into the Exception Handling module, referencing the policy you pass the HandleException method; that policy's configuration contains a LoggingExceptionHandler that references a logCategory; that logCategory should be added in the loggingConfiguration's categorySources section; that category references a listener; that listener should be added in the loggingConfiguration's listeners section, which specifies the name of the log file. One final note on error handling, as the proper way to handle WCF and MVC errors is a whole other very lengthy discussion. For AJAX calls to MVC action methods, depending on your configuration, an exception thrown here will result in ASP.NET'S Yellow Screen Of Death being sent back as a response, which is at best unnecessarily and uselessly verbose, and at worst a security risk as the internals of your application are exposed to potential hackers. I mitigated this by overriding my controller's OnException method, passing the exception off to the Exception Handling module as above. I created an ErrorModel class with as few properties as possible (e.g. an Error string), sending as little information to the client as possible, to both maximize bandwidth and mitigate risk. I then return an ErrorModel in JSON format for AJAX requests: if (filterContext.HttpContext.Request.IsAjaxRequest()){    filterContext.Result = Json(new ErrorModel(...));    filterContext.ExceptionHandled = true;} My $.ajax calls from the browser get a valid 200 OK response and go into the success handler. Before assuming everything is OK, I check if it's an ErrorModel or a model containing what I requested. If it's an ErrorModel, or null, I pass it to my error handler. If the client needs to handle different errors differently, ErrorModel can contain a flag, error code, string, etc. to differentiate, but again, sending as little information back as possible is ideal. Summary As any experienced ASP.NET developer knows, this is a far cry from where ASP.NET started when I began working with it 11 years ago. WCF services are far more powerful than ASMX ones, MVC is in many ways cleaner and certainly more unit test-friendly than Web Forms (if you don't consider the code/markup commingling you're doing again), the Enterprise Library makes error handling and logging almost entirely configuration-driven, AJAX makes a responsive UI more feasible, and jQuery makes JavaScript coding much less painful. It doesn't take much work to get a functional, maintainable, flexible application, though having it actually do something useful is a whole other matter.

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  • April 30th Links: ASP.NET, ASP.NET MVC, Visual Studio 2010

    Here is the latest in my link-listing series. [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] ASP.NET Data Web Control Enhancements in ASP.NET 4.0: Scott Mitchell has a good article that summarizes some of the nice improvements coming to the ASP.NET 4 data controls. Refreshing an ASP.NET AJAX UpdatePanel with JavaScript: Scott Mitchell has another nice article in his series...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • April 30th Links: ASP.NET, ASP.NET MVC, Visual Studio 2010

    Here is the latest in my link-listing series. [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] ASP.NET Data Web Control Enhancements in ASP.NET 4.0: Scott Mitchell has a good article that summarizes some of the nice improvements coming to the ASP.NET 4 data controls. Refreshing an ASP.NET AJAX UpdatePanel with JavaScript: Scott Mitchell has another nice article in his series...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • How to find and fix performance problems in ORM powered applications

    - by FransBouma
    Once in a while we get requests about how to fix performance problems with our framework. As it comes down to following the same steps and looking into the same things every single time, I decided to write a blogpost about it instead, so more people can learn from this and solve performance problems in their O/R mapper powered applications. In some parts it's focused on LLBLGen Pro but it's also usable for other O/R mapping frameworks, as the vast majority of performance problems in O/R mapper powered applications are not specific for a certain O/R mapper framework. Too often, the developer looks at the wrong part of the application, trying to fix what isn't a problem in that part, and getting frustrated that 'things are so slow with <insert your favorite framework X here>'. I'm in the O/R mapper business for a long time now (almost 10 years, full time) and as it's a small world, we O/R mapper developers know almost all tricks to pull off by now: we all know what to do to make task ABC faster and what compromises (because there are almost always compromises) to deal with if we decide to make ABC faster that way. Some O/R mapper frameworks are faster in X, others in Y, but you can be sure the difference is mainly a result of a compromise some developers are willing to deal with and others aren't. That's why the O/R mapper frameworks on the market today are different in many ways, even though they all fetch and save entities from and to a database. I'm not suggesting there's no room for improvement in today's O/R mapper frameworks, there always is, but it's not a matter of 'the slowness of the application is caused by the O/R mapper' anymore. Perhaps query generation can be optimized a bit here, row materialization can be optimized a bit there, but it's mainly coming down to milliseconds. Still worth it if you're a framework developer, but it's not much compared to the time spend inside databases and in user code: if a complete fetch takes 40ms or 50ms (from call to entity object collection), it won't make a difference for your application as that 10ms difference won't be noticed. That's why it's very important to find the real locations of the problems so developers can fix them properly and don't get frustrated because their quest to get a fast, performing application failed. Performance tuning basics and rules Finding and fixing performance problems in any application is a strict procedure with four prescribed steps: isolate, analyze, interpret and fix, in that order. It's key that you don't skip a step nor make assumptions: these steps help you find the reason of a problem which seems to be there, and how to fix it or leave it as-is. Skipping a step, or when you assume things will be bad/slow without doing analysis will lead to the path of premature optimization and won't actually solve your problems, only create new ones. The most important rule of finding and fixing performance problems in software is that you have to understand what 'performance problem' actually means. Most developers will say "when a piece of software / code is slow, you have a performance problem". But is that actually the case? If I write a Linq query which will aggregate, group and sort 5 million rows from several tables to produce a resultset of 10 rows, it might take more than a couple of milliseconds before that resultset is ready to be consumed by other logic. If I solely look at the Linq query, the code consuming the resultset of the 10 rows and then look at the time it takes to complete the whole procedure, it will appear to me to be slow: all that time taken to produce and consume 10 rows? But if you look closer, if you analyze and interpret the situation, you'll see it does a tremendous amount of work, and in that light it might even be extremely fast. With every performance problem you encounter, always do realize that what you're trying to solve is perhaps not a technical problem at all, but a perception problem. The second most important rule you have to understand is based on the old saying "Penny wise, Pound Foolish": the part which takes e.g. 5% of the total time T for a given task isn't worth optimizing if you have another part which takes a much larger part of the total time T for that same given task. Optimizing parts which are relatively insignificant for the total time taken is not going to bring you better results overall, even if you totally optimize that part away. This is the core reason why analysis of the complete set of application parts which participate in a given task is key to being successful in solving performance problems: No analysis -> no problem -> no solution. One warning up front: hunting for performance will always include making compromises. Fast software can be made maintainable, but if you want to squeeze as much performance out of your software, you will inevitably be faced with the dilemma of compromising one or more from the group {readability, maintainability, features} for the extra performance you think you'll gain. It's then up to you to decide whether it's worth it. In almost all cases it's not. The reason for this is simple: the vast majority of performance problems can be solved by implementing the proper algorithms, the ones with proven Big O-characteristics so you know the performance you'll get plus you know the algorithm will work. The time taken by the algorithm implementing code is inevitable: you already implemented the best algorithm. You might find some optimizations on the technical level but in general these are minor. Let's look at the four steps to see how they guide us through the quest to find and fix performance problems. Isolate The first thing you need to do is to isolate the areas in your application which are assumed to be slow. For example, if your application is a web application and a given page is taking several seconds or even minutes to load, it's a good candidate to check out. It's important to start with the isolate step because it allows you to focus on a single code path per area with a clear begin and end and ignore the rest. The rest of the steps are taken per identified problematic area. Keep in mind that isolation focuses on tasks in an application, not code snippets. A task is something that's started in your application by either another task or the user, or another program, and has a beginning and an end. You can see a task as a piece of functionality offered by your application.  Analyze Once you've determined the problem areas, you have to perform analysis on the code paths of each area, to see where the performance problems occur and which areas are not the problem. This is a multi-layered effort: an application which uses an O/R mapper typically consists of multiple parts: there's likely some kind of interface (web, webservice, windows etc.), a part which controls the interface and business logic, the O/R mapper part and the RDBMS, all connected with either a network or inter-process connections provided by the OS or other means. Each of these parts, including the connectivity plumbing, eat up a part of the total time it takes to complete a task, e.g. load a webpage with all orders of a given customer X. To understand which parts participate in the task / area we're investigating and how much they contribute to the total time taken to complete the task, analysis of each participating task is essential. Start with the code you wrote which starts the task, analyze the code and track the path it follows through your application. What does the code do along the way, verify whether it's correct or not. Analyze whether you have implemented the right algorithms in your code for this particular area. Remember we're looking at one area at a time, which means we're ignoring all other code paths, just the code path of the current problematic area, from begin to end and back. Don't dig in and start optimizing at the code level just yet. We're just analyzing. If your analysis reveals big architectural stupidity, it's perhaps a good idea to rethink the architecture at this point. For the rest, we're analyzing which means we collect data about what could be wrong, for each participating part of the complete application. Reviewing the code you wrote is a good tool to get deeper understanding of what is going on for a given task but ultimately it lacks precision and overview what really happens: humans aren't good code interpreters, computers are. We therefore need to utilize tools to get deeper understanding about which parts contribute how much time to the total task, triggered by which other parts and for example how many times are they called. There are two different kind of tools which are necessary: .NET profilers and O/R mapper / RDBMS profilers. .NET profiling .NET profilers (e.g. dotTrace by JetBrains or Ants by Red Gate software) show exactly which pieces of code are called, how many times they're called, and the time it took to run that piece of code, at the method level and sometimes even at the line level. The .NET profilers are essential tools for understanding whether the time taken to complete a given task / area in your application is consumed by .NET code, where exactly in your code, the path to that code, how many times that code was called by other code and thus reveals where hotspots are located: the areas where a solution can be found. Importantly, they also reveal which areas can be left alone: remember our penny wise pound foolish saying: if a profiler reveals that a group of methods are fast, or don't contribute much to the total time taken for a given task, ignore them. Even if the code in them is perhaps complex and looks like a candidate for optimization: you can work all day on that, it won't matter.  As we're focusing on a single area of the application, it's best to start profiling right before you actually activate the task/area. Most .NET profilers support this by starting the application without starting the profiling procedure just yet. You navigate to the particular part which is slow, start profiling in the profiler, in your application you perform the actions which are considered slow, and afterwards you get a snapshot in the profiler. The snapshot contains the data collected by the profiler during the slow action, so most data is produced by code in the area to investigate. This is important, because it allows you to stay focused on a single area. O/R mapper and RDBMS profiling .NET profilers give you a good insight in the .NET side of things, but not in the RDBMS side of the application. As this article is about O/R mapper powered applications, we're also looking at databases, and the software making it possible to consume the database in your application: the O/R mapper. To understand which parts of the O/R mapper and database participate how much to the total time taken for task T, we need different tools. There are two kind of tools focusing on O/R mappers and database performance profiling: O/R mapper profilers and RDBMS profilers. For O/R mapper profilers, you can look at LLBLGen Prof by hibernating rhinos or the Linq to Sql/LLBLGen Pro profiler by Huagati. Hibernating rhinos also have profilers for other O/R mappers like NHibernate (NHProf) and Entity Framework (EFProf) and work the same as LLBLGen Prof. For RDBMS profilers, you have to look whether the RDBMS vendor has a profiler. For example for SQL Server, the profiler is shipped with SQL Server, for Oracle it's build into the RDBMS, however there are also 3rd party tools. Which tool you're using isn't really important, what's important is that you get insight in which queries are executed during the task / area we're currently focused on and how long they took. Here, the O/R mapper profilers have an advantage as they collect the time it took to execute the query from the application's perspective so they also collect the time it took to transport data across the network. This is important because a query which returns a massive resultset or a resultset with large blob/clob/ntext/image fields takes more time to get transported across the network than a small resultset and a database profiler doesn't take this into account most of the time. Another tool to use in this case, which is more low level and not all O/R mappers support it (though LLBLGen Pro and NHibernate as well do) is tracing: most O/R mappers offer some form of tracing or logging system which you can use to collect the SQL generated and executed and often also other activity behind the scenes. While tracing can produce a tremendous amount of data in some cases, it also gives insight in what's going on. Interpret After we've completed the analysis step it's time to look at the data we've collected. We've done code reviews to see whether we've done anything stupid and which parts actually take place and if the proper algorithms have been implemented. We've done .NET profiling to see which parts are choke points and how much time they contribute to the total time taken to complete the task we're investigating. We've performed O/R mapper profiling and RDBMS profiling to see which queries were executed during the task, how many queries were generated and executed and how long they took to complete, including network transportation. All this data reveals two things: which parts are big contributors to the total time taken and which parts are irrelevant. Both aspects are very important. The parts which are irrelevant (i.e. don't contribute significantly to the total time taken) can be ignored from now on, we won't look at them. The parts which contribute a lot to the total time taken are important to look at. We now have to first look at the .NET profiler results, to see whether the time taken is consumed in our own code, in .NET framework code, in the O/R mapper itself or somewhere else. For example if most of the time is consumed by DbCommand.ExecuteReader, the time it took to complete the task is depending on the time the data is fetched from the database. If there was just 1 query executed, according to tracing or O/R mapper profilers / RDBMS profilers, check whether that query is optimal, uses indexes or has to deal with a lot of data. Interpret means that you follow the path from begin to end through the data collected and determine where, along the path, the most time is contributed. It also means that you have to check whether this was expected or is totally unexpected. My previous example of the 10 row resultset of a query which groups millions of rows will likely reveal that a long time is spend inside the database and almost no time is spend in the .NET code, meaning the RDBMS part contributes the most to the total time taken, the rest is compared to that time, irrelevant. Considering the vastness of the source data set, it's expected this will take some time. However, does it need tweaking? Perhaps all possible tweaks are already in place. In the interpret step you then have to decide that further action in this area is necessary or not, based on what the analysis results show: if the analysis results were unexpected and in the area where the most time is contributed to the total time taken is room for improvement, action should be taken. If not, you can only accept the situation and move on. In all cases, document your decision together with the analysis you've done. If you decide that the perceived performance problem is actually expected due to the nature of the task performed, it's essential that in the future when someone else looks at the application and starts asking questions you can answer them properly and new analysis is only necessary if situations changed. Fix After interpreting the analysis results you've concluded that some areas need adjustment. This is the fix step: you're actively correcting the performance problem with proper action targeted at the real cause. In many cases related to O/R mapper powered applications it means you'll use different features of the O/R mapper to achieve the same goal, or apply optimizations at the RDBMS level. It could also mean you apply caching inside your application (compromise memory consumption over performance) to avoid unnecessary re-querying data and re-consuming the results. After applying a change, it's key you re-do the analysis and interpretation steps: compare the results and expectations with what you had before, to see whether your actions had any effect or whether it moved the problem to a different part of the application. Don't fall into the trap to do partly analysis: do the full analysis again: .NET profiling and O/R mapper / RDBMS profiling. It might very well be that the changes you've made make one part faster but another part significantly slower, in such a way that the overall problem hasn't changed at all. Performance tuning is dealing with compromises and making choices: to use one feature over the other, to accept a higher memory footprint, to go away from the strict-OO path and execute queries directly onto the RDBMS, these are choices and compromises which will cross your path if you want to fix performance problems with respect to O/R mappers or data-access and databases in general. In most cases it's not a big issue: alternatives are often good choices too and the compromises aren't that hard to deal with. What is important is that you document why you made a choice, a compromise: which analysis data, which interpretation led you to the choice made. This is key for good maintainability in the years to come. Most common performance problems with O/R mappers Below is an incomplete list of common performance problems related to data-access / O/R mappers / RDBMS code. It will help you with fixing the hotspots you found in the interpretation step. SELECT N+1: (Lazy-loading specific). Lazy loading triggered performance bottlenecks. Consider a list of Orders bound to a grid. You have a Field mapped onto a related field in Order, Customer.CompanyName. Showing this column in the grid will make the grid fetch (indirectly) for each row the Customer row. This means you'll get for the single list not 1 query (for the orders) but 1+(the number of orders shown) queries. To solve this: use eager loading using a prefetch path to fetch the customers with the orders. SELECT N+1 is easy to spot with an O/R mapper profiler or RDBMS profiler: if you see a lot of identical queries executed at once, you have this problem. Prefetch paths using many path nodes or sorting, or limiting. Eager loading problem. Prefetch paths can help with performance, but as 1 query is fetched per node, it can be the number of data fetched in a child node is bigger than you think. Also consider that data in every node is merged on the client within the parent. This is fast, but it also can take some time if you fetch massive amounts of entities. If you keep fetches small, you can use tuning parameters like the ParameterizedPrefetchPathThreshold setting to get more optimal queries. Deep inheritance hierarchies of type Target Per Entity/Type. If you use inheritance of type Target per Entity / Type (each type in the inheritance hierarchy is mapped onto its own table/view), fetches will join subtype- and supertype tables in many cases, which can lead to a lot of performance problems if the hierarchy has many types. With this problem, keep inheritance to a minimum if possible, or switch to a hierarchy of type Target Per Hierarchy, which means all entities in the inheritance hierarchy are mapped onto the same table/view. Of course this has its own set of drawbacks, but it's a compromise you might want to take. Fetching massive amounts of data by fetching large lists of entities. LLBLGen Pro supports paging (and limiting the # of rows returned), which is often key to process through large sets of data. Use paging on the RDBMS if possible (so a query is executed which returns only the rows in the page requested). When using paging in a web application, be sure that you switch server-side paging on on the datasourcecontrol used. In this case, paging on the grid alone is not enough: this can lead to fetching a lot of data which is then loaded into the grid and paged there. Keep note that analyzing queries for paging could lead to the false assumption that paging doesn't occur, e.g. when the query contains a field of type ntext/image/clob/blob and DISTINCT can't be applied while it should have (e.g. due to a join): the datareader will do DISTINCT filtering on the client. this is a little slower but it does perform paging functionality on the data-reader so it won't fetch all rows even if the query suggests it does. Fetch massive amounts of data because blob/clob/ntext/image fields aren't excluded. LLBLGen Pro supports field exclusion for queries. You can exclude fields (also in prefetch paths) per query to avoid fetching all fields of an entity, e.g. when you don't need them for the logic consuming the resultset. Excluding fields can greatly reduce the amount of time spend on data-transport across the network. Use this optimization if you see that there's a big difference between query execution time on the RDBMS and the time reported by the .NET profiler for the ExecuteReader method call. Doing client-side aggregates/scalar calculations by consuming a lot of data. If possible, try to formulate a scalar query or group by query using the projection system or GetScalar functionality of LLBLGen Pro to do data consumption on the RDBMS server. It's far more efficient to process data on the RDBMS server than to first load it all in memory, then traverse the data in-memory to calculate a value. Using .ToList() constructs inside linq queries. It might be you use .ToList() somewhere in a Linq query which makes the query be run partially in-memory. Example: var q = from c in metaData.Customers.ToList() where c.Country=="Norway" select c; This will actually fetch all customers in-memory and do an in-memory filtering, as the linq query is defined on an IEnumerable<T>, and not on the IQueryable<T>. Linq is nice, but it can often be a bit unclear where some parts of a Linq query might run. Fetching all entities to delete into memory first. To delete a set of entities it's rather inefficient to first fetch them all into memory and then delete them one by one. It's more efficient to execute a DELETE FROM ... WHERE query on the database directly to delete the entities in one go. LLBLGen Pro supports this feature, and so do some other O/R mappers. It's not always possible to do this operation in the context of an O/R mapper however: if an O/R mapper relies on a cache, these kind of operations are likely not supported because they make it impossible to track whether an entity is actually removed from the DB and thus can be removed from the cache. Fetching all entities to update with an expression into memory first. Similar to the previous point: it is more efficient to update a set of entities directly with a single UPDATE query using an expression instead of fetching the entities into memory first and then updating the entities in a loop, and afterwards saving them. It might however be a compromise you don't want to take as it is working around the idea of having an object graph in memory which is manipulated and instead makes the code fully aware there's a RDBMS somewhere. Conclusion Performance tuning is almost always about compromises and making choices. It's also about knowing where to look and how the systems in play behave and should behave. The four steps I provided should help you stay focused on the real problem and lead you towards the solution. Knowing how to optimally use the systems participating in your own code (.NET framework, O/R mapper, RDBMS, network/services) is key for success as well as knowing what's going on inside the application you built. I hope you'll find this guide useful in tracking down performance problems and dealing with them in a useful way.  

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  • March 21st Links: ASP.NET, ASP.NET MVC, AJAX, Visual Studio, Silverlight

    Here is the latest in my link-listing series. If you havent already, check out this months "Find a Hoster page on the www.asp.net website to learn about great (and very inexpensive) ASP.NET hosting offers.  [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] ASP.NET URL Routing in ASP.NET 4: Scott Mitchell has a nice article that talks about the new URL routing features coming to Web Forms...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • What exactly is "Web API" in ASP.Net MVC4?

    - by James P. Wright
    I know what a Web API is. I've written API's in multiple languages (including in MVC3). I'm also well practiced in ASP.Net. I just discovered that MVC4 has "Web API" and without going through the video examples I can't find a good explanation of what exactly it IS. From my past experience, Microsoft technologies (especially ASP.Net) have a tendency to take a simple concept and wrap it in a bunch of useless overhead that is meant to make everything "easier". Can someone please explain to me what Web API in MVC4 is exactly? Why do I need it? Why can't I just write my own API?

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  • Was it necessary to build this site in ASP.NET ?

    - by Andrew M
    From what I'm told, the whole StackOverflow/StackExchange 'stack' is based on Microsoft's ASP.NET. SO and the SE sites are probably the most complex that I visit on a regular basis. There's a lot going on in every page - lots of different boxes, pulling data from different places and changing dynamically and responding to user interaction. And the sites work very smoothly, despite the high traffic. My question is, could this have been achieved using a different platform/framework? Does ASP.NET lend itself to more complex projects where other web frameworks would strain and falter? Or is the choice pretty incidental?

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  • weblogs.asp.net! I am here now!

    - by kaushalparik27
    Hello all webloggers!! Finally after much wait I got my blog space approved here. I really want to thank moderators (specially Terry for mail follow up) helping me out creating my weblog here. I; usually; blog about things and situation that I come across while development or something on which I succeeded to have some study/reading. Till now, I was maintaining my blog here (which I am still going to maintain in future as well!). Wishing for the best and thanks all future readers!

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  • What is the compatibility on .NET 4.0?

    - by Juan Manuel Formoso
    We have several .NET applications developed in .NET 3.5 (Windows services, web applications, and WCF services) in different servers. I'd like to migrate to .NET 4.0 and use VS.NET 2010. Does VS.NET 2010 compiles to .NET 3.5 to avoid full simultaneous migration, being able to stop using VS.NET 2008 but maintaining some applications in the previous version? Can I uninstall the .NET < 4.0 runtime and have only .NET 4.0 in my servers? Does it run applications compiled to previous framework versions?

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