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• Distributed and/or Parallel SSIS processing

  - by Jeff

  Background: Our company hosts SaaS DSS applications, where clients provide us data Daily and/or Weekly, which we process & merge into their existing database. During business hours, load in the servers are pretty minimal as it's mostly users running simple pre-defined queries via the website, or running drill-through reports that mostly hit the SSAS OLAP cube. I manage the IT Operations Team, and so far this has presented an interesting "scaling" issue for us. For our daily-refreshed clients, the server is only "busy" for about 4-6 hrs at night. For our weekly-refresh clients, the server is only "busy" for maybe 8-10 hrs per week! We've done our best to use some simple methods of distributing the load by spreading the daily clients evenly among the servers such that we're not trying to process daily clients back-to-back over night. But long-term this scaling strategy creates two notable issues. First, it's going to consume a pretty immense amount of hardware that sits idle for large periods of time. Second, it takes significant Production Support over-head to basically "schedule" the ETL such that they don't over-lap, and move clients/schedules around if they out-grow the resources on a particular server or allocated time-slot. As the title would imply, one option we've tried is running multiple SSIS packages in parallel, but in most cases this has yielded VERY inconsistent results. The most common failures are DTExec, SQL, and SSAS fighting for physical memory and throwing out-of-memory errors, and ETLs running 3,4,5x longer than expected. So from my practical experience thus far, it seems like running multiple ETL packages on the same hardware isn't a good idea, but I can't be the first person that doesn't want to scale multiple ETLs around manual scheduling, and sequential processing. One option we've considered is virtualizing the servers, which obviously doesn't give you any additional resources, but moves the resource contention onto the hypervisor, which (from my experience) seems to manage simultaneous CPU/RAM/Disk I/O a little more gracefully than letting DTExec, SQL, and SSAS battle it out within Windows. Question to the forum: So my question to the forum is, are we missing something obvious here? Are there tools out there that can help manage running multiple SSIS packages on the same hardware? Would it be more "efficient" in terms of parallel execution if instead of running DTExec, SQL, and SSAS same machine (with every machine running that configuration), we run in pairs of three machines with SSIS running on one machine, SQL on another, and SSAS on a third? Obviously that would only make sense if we could process more than the three ETL we were able to process on the machine independently. Another option we've considered is completely re-architecting our SSIS package to have one "master" package for all clients that attempts to intelligently chose a server based off how "busy" it already is in terms of CPU/Memory/Disk utilization, but that would be a herculean effort, and seems like we're trying to reinvent something that you would think someone would sell (although I haven't had any luck finding it). So in summary, are we missing an obvious solution for this, and does anyone know if any tools (for free or for purchase, doesn't matter) that facilitate running multiple SSIS ETL packages in parallel and on multiple servers? (What I would call a "queue & node based" system, but that's not an official term). Ultimately VMWare's Distributed Resource Scheduler addresses this as you simply run a consistent number of clients per VM that you know will never conflict scheduleing-wise, then leave it up to VMWare to move the VMs around to balance out hardware usage. I'm definitely not against using VMWare to do this, but since we're a 100% Microsoft app stack, it seems like -someone- out there would have solved this problem at the application layer instead of the hypervisor layer by checking on resource utilization at the OS, SQL, SSAS levels. I'm open to ANY discussion on this, and remember no suggestion is too crazy or radical! :-) Right now, VMWare is the only option we've found to get away from "manually" balancing our resources, so any suggestions that leave us on a pure Microsoft stack would be great. Thanks guys, Jeff

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• Nginx + php-fpm "504 Gateway Time-out" error with almost zero load (on a test-server)

  - by rahul286

  After debugging for 6-hours - I am giving this up :| We have a nginx+php-fpm+mysql in LAN with almost 100 wordpress (created and used by different designers/developers all working on test wordpres setup) We are using nginx without any issues from long. Today, all of a sudden - nginx started returning "504 Gateway Time-out" out of the blue... I checked nginx error log for a virtual host... 2010/09/06 21:24:24 [error] 12909#0: *349 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 21:25:11 [error] 12909#0: *349 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 21:25:11 [error] 12909#0: *443 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /info.php HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 21:25:12 [error] 12909#0: *443 connect() failed (111: Connection refused) while connecting to upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:08:32 [error] 12909#0: *1025 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:09:33 [error] 12909#0: *1025 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:09:40 [error] 12909#0: *1064 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /info.php HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:09:40 [error] 12909#0: *1064 connect() failed (111: Connection refused) while connecting to upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:24:44 [error] 12909#0: *1313 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:24:53 [error] 12909#0: *1313 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" As I run php-fpm on port 9000 via TCP mode, I ran "netstat | grep 9000" and noticed something unusual... (Pasting partial output here for ease of read) tcp 9 0 localhost:9000 localhost:36094 CLOSE_WAIT 14269/php5-fpm tcp 0 0 localhost:46664 localhost:9000 FIN_WAIT2 - tcp 1257 0 localhost:9000 localhost:36135 CLOSE_WAIT - tcp 1257 0 localhost:9000 localhost:36125 CLOSE_WAIT - tcp 9 0 localhost:9000 localhost:36102 CLOSE_WAIT 14268/php5-fpm tcp 0 0 localhost:46662 localhost:9000 FIN_WAIT2 - tcp 745 0 localhost:9000 localhost:46644 CLOSE_WAIT - tcp 0 0 localhost:46658 localhost:9000 FIN_WAIT2 - tcp 1265 0 localhost:9000 localhost:46607 CLOSE_WAIT - tcp 0 0 localhost:46672 localhost:9000 ESTABLISHED 12909/nginx: worker tcp 1257 0 localhost:9000 localhost:36119 CLOSE_WAIT - tcp 1265 0 localhost:9000 localhost:46613 CLOSE_WAIT - tcp 0 0 localhost:46646 localhost:9000 FIN_WAIT2 - tcp 1257 0 localhost:9000 localhost:36137 CLOSE_WAIT - tcp 0 0 localhost:46670 localhost:9000 ESTABLISHED 12909/nginx: worker tcp 1265 0 localhost:9000 localhost:46619 CLOSE_WAIT - tcp 1336 0 localhost:9000 localhost:46668 ESTABLISHED - tcp 0 0 localhost:46648 localhost:9000 FIN_WAIT2 - tcp 1336 0 localhost:9000 localhost:46670 ESTABLISHED - tcp 9 0 localhost:9000 localhost:36108 CLOSE_WAIT 14274/php5-fpm tcp 1336 0 localhost:9000 localhost:46684 ESTABLISHED - tcp 0 0 localhost:46674 localhost:9000 ESTABLISHED 12909/nginx: worker tcp 1336 0 localhost:9000 localhost:46666 ESTABLISHED - tcp 1257 0 localhost:9000 localhost:46648 CLOSE_WAIT - tcp 1336 0 localhost:9000 localhost:46678 ESTABLISHED - tcp 0 0 localhost:46668 localhost:9000 ESTABLISHED 12909/nginx: wo There are plenty of "CLOSE_WAIT" & "FIN_WAIT2" pairs as highlighted below (in above output): tcp 1337 0 localhost:9000 localhost:46680 CLOSE_WAIT - tcp 0 0 localhost:46680 localhost:9000 FIN_WAIT2 - Please note port 46680 in above. I enabled mysql slow queries error log, but it didn't work. As of now restarting php5-fpm every minute via a cronjob (see command below) keeping everything running "smoothly" but I hate patchwork and want to solve this... 1 * * * * service php5-fpm restart > /dev/null I searched extensively on Google - got no help. As mentioned, this a test-server in LAN, CPU load is never crossed 0.10 and memory usage is also below 25% (System has 2GB RAM and ubuntu-server installed) So if you find its time-confusing to help me out, please atleast drop a hint. Thanks in advance for help. -Rahul (note - this is reposting of - http://forum.nginx.org/read.php?11,127694) Update: I found answer, which is posted below.

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• Dynamic JSON Parsing in .NET with JsonValue

  - by Rick Strahl

  So System.Json has been around for a while in Silverlight, but it's relatively new for the desktop .NET framework and now moving into the lime-light with the pending release of ASP.NET Web API which is bringing a ton of attention to server side JSON usage. The JsonValue, JsonObject and JsonArray objects are going to be pretty useful for Web API applications as they allow you dynamically create and parse JSON values without explicit .NET types to serialize from or into. But even more so I think JsonValue et al. are going to be very useful when consuming JSON APIs from various services. Yes I know C# is strongly typed, why in the world would you want to use dynamic values? So many times I've needed to retrieve a small morsel of information from a large service JSON response and rather than having to map the entire type structure of what that service returns, JsonValue actually allows me to cherry pick and only work with the values I'm interested in, without having to explicitly create everything up front. With JavaScriptSerializer or DataContractJsonSerializer you always need to have a strong type to de-serialize JSON data into. Wouldn't it be nice if no explicit type was required and you could just parse the JSON directly using a very easy to use object syntax? That's exactly what JsonValue, JsonObject and JsonArray accomplish using a JSON parser and some sweet use of dynamic sauce to make it easy to access in code. Creating JSON on the fly with JsonValue Let's start with creating JSON on the fly. It's super easy to create a dynamic object structure. JsonValue uses the dynamic  keyword extensively to make it intuitive to create object structures and turn them into JSON via dynamic object syntax. Here's an example of creating a music album structure with child songs using JsonValue:[TestMethod] public void JsonValueOutputTest() { // strong type instance var jsonObject = new JsonObject(); // dynamic expando instance you can add properties to dynamic album = jsonObject; album.AlbumName = "Dirty Deeds Done Dirt Cheap"; album.Artist = "AC/DC"; album.YearReleased = 1977; album.Songs = new JsonArray() as dynamic; dynamic song = new JsonObject(); song.SongName = "Dirty Deeds Done Dirt Cheap"; song.SongLength = "4:11"; album.Songs.Add(song); song = new JsonObject(); song.SongName = "Love at First Feel"; song.SongLength = "3:10"; album.Songs.Add(song); Console.WriteLine(album.ToString()); } This produces proper JSON just as you would expect: {"AlbumName":"Dirty Deeds Done Dirt Cheap","Artist":"AC\/DC","YearReleased":1977,"Songs":[{"SongName":"Dirty Deeds Done Dirt Cheap","SongLength":"4:11"},{"SongName":"Love at First Feel","SongLength":"3:10"}]} The important thing about this code is that there's no explicitly type that is used for holding the values to serialize to JSON. I am essentially creating this value structure on the fly by adding properties and then serialize it to JSON. This means this code can be entirely driven at runtime without compile time restraints of structure for the JSON output. Here I use JsonObject() to create a new object and immediately cast it to dynamic. JsonObject() is kind of similar in behavior to ExpandoObject in that it allows you to add properties by simply assigning to them. Internally, JsonValue/JsonObject these values are stored in pseudo collections of key value pairs that are exposed as properties through the DynamicObject functionality in .NET. The syntax gets a little tedious only if you need to create child objects or arrays that have to be explicitly defined first. Other than that the syntax looks like normal object access sytnax. Always remember though these values are dynamic - which means no Intellisense and no compiler type checking. It's up to you to ensure that the values you create are accessed consistently and without typos in your code. Note that you can also access the JsonValue instance directly and get access to the underlying type. This means you can assign properties by string, which can be useful for fully data driven JSON generation from other structures. Below you can see both styles of access next to each other:// strong type instance var jsonObject = new JsonObject(); // you can explicitly add values here jsonObject.Add("Entered", DateTime.Now); // expando style instance you can just 'use' properties dynamic album = jsonObject; album.AlbumName = "Dirty Deeds Done Dirt Cheap"; JsonValue internally stores properties keys and values in collections and you can iterate over them at runtime. You can also manipulate the collections if you need to to get the object structure to look exactly like you want. Again, if you've used ExpandoObject before JsonObject/Value are very similar in the behavior of the structure. Reading JSON strings into JsonValue The JsonValue structure supports importing JSON via the Parse() and Load() methods which can read JSON data from a string or various streams respectively. Essentially JsonValue includes the core JSON parsing to turn a JSON string into a collection of JsonValue objects that can be then referenced using familiar dynamic object syntax. Here's a simple example:[TestMethod] public void JsonValueParsingTest() { var jsonString = @"{""Name"":""Rick"",""Company"":""West Wind"",""Entered"":""2012-03-16T00:03:33.245-10:00""}"; dynamic json = JsonValue.Parse(jsonString); // values require casting string name = json.Name; string company = json.Company; DateTime entered = json.Entered; Assert.AreEqual(name, "Rick"); Assert.AreEqual(company, "West Wind"); } The JSON string represents an object with three properties which is parsed into a JsonValue object and cast to dynamic. Once cast to dynamic I can then go ahead and access the object using familiar object syntax. Note that the actual values - json.Name, json.Company, json.Entered - are actually of type JsonPrimitive and I have to assign them to their appropriate types first before I can do type comparisons. The dynamic properties will automatically cast to the right type expected as long as the compiler can resolve the type of the assignment or usage. The AreEqual() method oesn't as it expects two object instances and comparing json.Company to "West Wind" is comparing two different types (JsonPrimitive to String) which fails. So the intermediary assignment is required to make the test pass. The JSON structure can be much more complex than this simple example. Here's another example of an array of albums serialized to JSON and then parsed through with JsonValue():[TestMethod] public void JsonArrayParsingTest() { var jsonString = @"[ { ""Id"": ""b3ec4e5c"", ""AlbumName"": ""Dirty Deeds Done Dirt Cheap"", ""Artist"": ""AC/DC"", ""YearReleased"": 1977, ""Entered"": ""2012-03-16T00:13:12.2810521-10:00"", ""AlbumImageUrl"": ""http://ecx.images-amazon.com/images/I/61kTaH-uZBL._AA115_.jpg"", ""AmazonUrl"": ""http://www.amazon.com/gp/product/B00008BXJ4/ref=as_li_ss_tl?ie=UTF8&tag=westwindtechn-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B00008BXJ4"", ""Songs"": [ { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Dirty Deeds Done Dirt Cheap"", ""SongLength"": ""4:11"" }, { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Love at First Feel"", ""SongLength"": ""3:10"" }, { ""AlbumId"": ""b3ec4e5c"", ""SongName"": ""Big Balls"", ""SongLength"": ""2:38"" } ] }, { ""Id"": ""67280fb8"", ""AlbumName"": ""Echoes, Silence, Patience & Grace"", ""Artist"": ""Foo Fighters"", ""YearReleased"": 2007, ""Entered"": ""2012-03-16T00:13:12.2810521-10:00"", ""AlbumImageUrl"": ""http://ecx.images-amazon.com/images/I/41mtlesQPVL._SL500_AA280_.jpg"", ""AmazonUrl"": ""http://www.amazon.com/gp/product/B000UFAURI/ref=as_li_ss_tl?ie=UTF8&tag=westwindtechn-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B000UFAURI"", ""Songs"": [ { ""AlbumId"": ""67280fb8"", ""SongName"": ""The Pretender"", ""SongLength"": ""4:29"" }, { ""AlbumId"": ""67280fb8"", ""SongName"": ""Let it Die"", ""SongLength"": ""4:05"" }, { ""AlbumId"": ""67280fb8"", ""SongName"": ""Erase/Replay"", ""SongLength"": ""4:13"" } ] }, { ""Id"": ""7b919432"", ""AlbumName"": ""End of the Silence"", ""Artist"": ""Henry Rollins Band"", ""YearReleased"": 1992, ""Entered"": ""2012-03-16T00:13:12.2800521-10:00"", ""AlbumImageUrl"": ""http://ecx.images-amazon.com/images/I/51FO3rb1tuL._SL160_AA160_.jpg"", ""AmazonUrl"": ""http://www.amazon.com/End-Silence-Rollins-Band/dp/B0000040OX/ref=sr_1_5?ie=UTF8&qid=1302232195&sr=8-5"", ""Songs"": [ { ""AlbumId"": ""7b919432"", ""SongName"": ""Low Self Opinion"", ""SongLength"": ""5:24"" }, { ""AlbumId"": ""7b919432"", ""SongName"": ""Grip"", ""SongLength"": ""4:51"" } ] } ]"; dynamic albums = JsonValue.Parse(jsonString); foreach (dynamic album in albums) { Console.WriteLine(album.AlbumName + " (" + album.YearReleased.ToString() + ")"); foreach (dynamic song in album.Songs) { Console.WriteLine("\t" + song.SongName ); } } Console.WriteLine(albums[0].AlbumName); Console.WriteLine(albums[0].Songs[1].SongName);}   It's pretty sweet how easy it becomes to parse even complex JSON and then just run through the object using object syntax, yet without an explicit type in the mix. In fact it looks and feels a lot like if you were using JavaScript to parse through this data, doesn't it? And that's the point…© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET  Web Api  JSON   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• error CS0177: The out parameter 'Wx' must be assigned to before control leaves the current method

  - by sonny5

  using System; using System.Drawing; using System.Drawing.Drawing2D; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Data; public class Form1 : System.Windows.Forms.Form { public static float WXmin; public static float WYmin; public static float WXmax; public static float WYmax; public static int VXmin; public static int VYmin; public static int VXmax; public static int VYmax; public static float Vx; public static float Vy; public Form1() { InitializeComponent(); } private void InitializeComponent() { //this.AutoScaleBaseSize = new System.Drawing.Size(5, 13); this.ClientSize = new System.Drawing.Size(400, 300); this.Text="Pass Args"; this.Paint += new System.Windows.Forms.PaintEventHandler(this.doLine); } static void Main() { Application.Run(new Form1()); } private void doLine(object sender, System.Windows.Forms.PaintEventArgs e) { Graphics g = e.Graphics; g.FillRectangle(Brushes.White, this.ClientRectangle); Pen p = new Pen(Color.Black); g.DrawLine(p, 0, 0, 100, 100); p.Dispose(); } private void eachCornerPix (object sender, PaintEventArgs e, out float Wx, out float Wy, out float Vx, out float Vy) { Graphics g = this.CreateGraphics(); Pen penBlu = new Pen(Color.Blue, 2); SolidBrush redBrush = new SolidBrush(Color.Red); int width = 2; // 1 pixel wide in x int height = 2; float [] Wxc = {0.100f, 5.900f, 5.900f, 0.100f}; float [] Wyc = {0.100f, 0.100f, 3.900f, 3.900f}; for (int i = 0; i<3; i++) { Wx = Wxc[i]; Wy = Wyc[i]; Vx = ((Wx - WXmin)*((VXmax-VXmin)+VXmin)/(WXmax-WXmin)); Vy = ((Wy - WYmin)*(VYmax-VYmin)/(WYmax-WYmin)+VYmin); Console.WriteLine("eachCornerPix Vx= {0}", Vx); Console.WriteLine("eachCornerPix Vy= {0}", Vy); g.FillRectangle(redBrush, Vx, Vy, width, height); g.Dispose(); } // Desired effect: Use the array values (Wxc, Wyc) and re-assign them to Wx and Wy. Then use // Wx and Wy as components to calculate Vx and Vy. // My end goal...once compile issues are resolved, is to pass each array value listed // using this method. This should allow 4 xy point pairs to be plotted. // Errors: // pass1.cs(51,18): error CS0177: The out parameter 'Wx' must be assigned to before // control leaves the current method // pass1.cs(51,18): error CS0177: The out parameter 'Wy' must be assigned to before // control leaves the current method // pass1.cs(51,18): error CS0177: The out parameter 'Vx' must be assigned to before // control leaves the current method // pass1.cs(51,18): error CS0177: The out parameter 'Vy' must be assigned to before // control leaves the current method } }

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• Creating HTML5 Offline Web Applications with ASP.NET

  - by Stephen Walther

  The goal of this blog entry is to describe how you can create HTML5 Offline Web Applications when building ASP.NET web applications. I describe the method that I used to create an offline Web application when building the JavaScript Reference application. You can read about the HTML5 Offline Web Application standard by visiting the following links: Offline Web Applications Firefox Offline Web Applications Safari Offline Web Applications Currently, the HTML5 Offline Web Applications feature works with all modern browsers with one important exception. You can use Offline Web Applications with Firefox, Chrome, and Safari (including iPhone Safari). Unfortunately, however, Internet Explorer does not support Offline Web Applications (not even IE 9). Why Build an HTML5 Offline Web Application? The official reason to build an Offline Web Application is so that you do not need to be connected to the Internet to use it. For example, you can use the JavaScript Reference Application when flying in an airplane, riding a subway, or hiding in a cave in Borneo. The JavaScript Reference Application works great on my iPhone even when I am completely disconnected from any network. The following screenshot shows the JavaScript Reference Application running on my iPhone when airplane mode is enabled (notice the little orange airplane):   Admittedly, it is becoming increasingly difficult to find locations where you can’t get Internet access. A second, and possibly better, reason to create Offline Web Applications is speed. An Offline Web Application must be downloaded only once. After it gets downloaded, all of the files required by your Web application (HTML, CSS, JavaScript, Image) are stored persistently on your computer. Think of Offline Web Applications as providing you with a super browser cache. Normally, when you cache files in a browser, the files are cached on a file-by-file basis. For each HTML, CSS, image, or JavaScript file, you specify how long the file should remain in the cache by setting cache headers. Unlike the normal browser caching mechanism, the HTML5 Offline Web Application cache is used to specify a caching policy for an entire set of files. You use a manifest file to list the files that you want to cache and these files are cached until the manifest is changed. Another advantage of using the HTML5 offline cache is that the HTML5 standard supports several JavaScript events and methods related to the offline cache. For example, you can be notified in your JavaScript code whenever the offline application has been updated. You can use JavaScript methods, such as the ApplicationCache.update() method, to update the cache programmatically. Creating the Manifest File The HTML5 Offline Cache uses a manifest file to determine the files that get cached. Here’s what the manifest file looks like for the JavaScript Reference application: CACHE MANIFEST # v30 Default.aspx # Standard Script Libraries Scripts/jquery-1.4.4.min.js Scripts/jquery-ui-1.8.7.custom.min.js Scripts/jquery.tmpl.min.js Scripts/json2.js # App Scripts App_Scripts/combine.js App_Scripts/combine.debug.js # Content (CSS & images) Content/default.css Content/logo.png Content/ui-lightness/jquery-ui-1.8.7.custom.css Content/ui-lightness/images/ui-bg_glass_65_ffffff_1x400.png Content/ui-lightness/images/ui-bg_glass_100_f6f6f6_1x400.png Content/ui-lightness/images/ui-bg_highlight-soft_100_eeeeee_1x100.png Content/ui-lightness/images/ui-icons_222222_256x240.png Content/ui-lightness/images/ui-bg_glass_100_fdf5ce_1x400.png Content/ui-lightness/images/ui-bg_diagonals-thick_20_666666_40x40.png Content/ui-lightness/images/ui-bg_gloss-wave_35_f6a828_500x100.png Content/ui-lightness/images/ui-icons_ffffff_256x240.png Content/ui-lightness/images/ui-icons_ef8c08_256x240.png Content/browsers/c8.png Content/browsers/es3.png Content/browsers/es5.png Content/browsers/ff3_6.png Content/browsers/ie8.png Content/browsers/ie9.png Content/browsers/sf5.png NETWORK: Services/EntryService.svc http://superexpert.com/resources/JavaScriptReference/ A Cache Manifest file always starts with the line of text Cache Manifest. In the manifest above, all of the CSS, image, and JavaScript files required by the JavaScript Reference application are listed. For example, the Default.aspx ASP.NET page, jQuery library, JQuery UI library, and several images are listed. Notice that you can add comments to a manifest by starting a line with the hash character (#). I use comments in the manifest above to group JavaScript and image files. Finally, notice that there is a NETWORK: section of the manifest. You list any file that you do not want to cache (any file that requires network access) in this section. In the manifest above, the NETWORK: section includes the URL for a WCF Service named EntryService.svc. This service is called to get the JavaScript entries displayed by the JavaScript Reference. There are two important things that you need to be aware of when using a manifest file. First, all relative URLs listed in a manifest are resolved relative to the manifest file. The URLs listed in the manifest above are all resolved relative to the root of the application because the manifest file is located in the application root. Second, whenever you make a change to the manifest file, browsers will download all of the files contained in the manifest (all of them). For example, if you add a new file to the manifest then any browser that supports the Offline Cache standard will detect the change in the manifest and download all of the files listed in the manifest automatically. If you make changes to files in the manifest (for example, modify a JavaScript file) then you need to make a change in the manifest file in order for the new version of the file to be downloaded. The standard way of updating a manifest file is to include a comment with a version number. The manifest above includes a # v30 comment. If you make a change to a file then you need to modify the comment to be # v31 in order for the new file to be downloaded. When Are Updated Files Downloaded? When you make changes to a manifest, the changes are not reflected the very next time you open the offline application in your web browser. Your web browser will download the updated files in the background. This can be very confusing when you are working with JavaScript files. If you make a change to a JavaScript file, and you have cached the application offline, then the changes to the JavaScript file won’t appear when you reload the application. The HTML5 standard includes new JavaScript events and methods that you can use to track changes and make changes to the Application Cache. You can use the ApplicationCache.update() method to initiate an update to the application cache and you can use the ApplicationCache.swapCache() method to switch to the latest version of a cached application. My heartfelt recommendation is that you do not enable your application for offline storage until after you finish writing your application code. Otherwise, debugging the application can become a very confusing experience. Offline Web Applications versus Local Storage Be careful to not confuse the HTML5 Offline Web Application feature and HTML5 Local Storage (aka DOM storage) feature. The JavaScript Reference Application uses both features. HTML5 Local Storage enables you to store key/value pairs persistently. Think of Local Storage as a super cookie. I describe how the JavaScript Reference Application uses Local Storage to store the database of JavaScript entries in a separate blog entry. Offline Web Applications enable you to store static files persistently. Think of Offline Web Applications as a super cache. Creating a Manifest File in an ASP.NET Application A manifest file must be served with the MIME type text/cache-manifest. In order to serve the JavaScript Reference manifest with the proper MIME type, I added two files to the JavaScript Reference Application project: Manifest.txt – This text file contains the actual manifest file. Manifest.ashx – This generic handler sends the Manifest.txt file with the MIME type text/cache-manifest. Here’s the code for the generic handler: using System.Web; namespace JavaScriptReference { public class Manifest : IHttpHandler { public void ProcessRequest(HttpContext context) { context.Response.ContentType = "text/cache-manifest"; context.Response.WriteFile(context.Server.MapPath("Manifest.txt")); } public bool IsReusable { get { return false; } } } } The Default.aspx file contains a reference to the manifest. The opening HTML tag in the Default.aspx file looks like this: <html manifest="Manifest.ashx"> Notice that the HTML tag contains a manifest attribute that points to the Manifest.ashx generic handler. Internet Explorer simply ignores this attribute. Every other modern browser will download the manifest when the Default.aspx page is requested. Seeing the Offline Web Application in Action The experience of using an HTML5 Web Application is different with different browsers. When you first open the JavaScript Reference application with Firefox, you get the following warning: Notice that you are provided with the choice of whether you want to use the application offline or not. Browsers other than Firefox, such as Chrome and Safari, do not provide you with this choice. Chrome and Safari will create an offline cache automatically. If you click the Allow button then Firefox will download all of the files listed in the manifest. You can view the files contained in the Firefox offline application cache by typing about:cache in the Firefox address bar: You can view the actual items being cached by clicking the List Cache Entries link: The Offline Web Application experience is different in the case of Google Chrome. You can view the entries in the offline cache by opening the Developer Tools (hit Shift+CTRL+I), selecting the Storage tab, and selecting Application Cache: Notice that you view the status of the Application Cache. In the screen shot above, the status is UNCACHED which means that the files listed in the manifest have not been downloaded and cached yet. The different possible values for the status are included in the HTML5 Offline Web Application standard: UNCACHED – The Application Cache has not been initialized. IDLE – The Application Cache is not currently being updated. CHECKING – The Application Cache is being fetched and checked for updates. DOWNLOADING – The files in the Application Cache are being updated. UPDATEREADY – There is a new version of the Application. OBSOLETE – The contents of the Application Cache are obsolete. Summary In this blog entry, I provided a description of how you can use the HTML5 Offline Web Application feature in the context of an ASP.NET application. I described how this feature is used with the JavaScript Reference Application to store the entire application on a user’s computer. By taking advantage of this new feature of the HTML5 standard, you can improve the performance of your ASP.NET web applications by requiring users of your web application to download your application once and only once. Furthermore, you can enable users to take advantage of your applications anywhere -- regardless of whether or not they are connected to the Internet.

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• .NET Framework generates strange DCOM error

  - by Anders Oestergaard Jensen

  Hello, I am creating a simple application that enables merging of key-value pairs fields in a Word and/or Excel document. Until this day, the application has worked out just fine. I am using the latest version of .NET Framework 4.0 (since it provides a nice wrapper API for Interop). My sample merging method looks like this: public byte[] ProcessWordDocument(string path, List<KeyValuePair<string, string>> kvs) { logger.InfoFormat("ProcessWordDocument: path = {0}", path); var localWordapp = new Word.Application(); localWordapp.Visible = false; Word.Document doc = null; try { doc = localWordapp.Documents.Open(path, ReadOnly: false); logger.Debug("Executing Find->Replace..."); foreach (Word.Range r in doc.StoryRanges) { foreach (KeyValuePair<string, string> kv in kvs) { r.Find.Execute(Replace: Word.WdReplace.wdReplaceAll, FindText: kv.Key, ReplaceWith: kv.Value, Wrap: Word.WdFindWrap.wdFindContinue); } } logger.Debug("Done! Saving document and cleaning up"); doc.Save(); doc.Close(); System.Runtime.InteropServices.Marshal.ReleaseComObject(doc); localWordapp.Quit(); System.Runtime.InteropServices.Marshal.ReleaseComObject(localWordapp); logger.Debug("Done."); return System.IO.File.ReadAllBytes(path); } catch (Exception ex) { // Logging... // doc.Close(); if (doc != null) { doc.Close(); System.Runtime.InteropServices.Marshal.ReleaseComObject(doc); } localWordapp.Quit(); System.Runtime.InteropServices.Marshal.ReleaseComObject(localWordapp); throw; } } The above C# snippet has worked all fine (compiled and deployed unto a Windows Server 2008 x64) with latest updates installed. But now, suddenly, I get the following strange error: System.Runtime.InteropServices.COMException (0x80080005): Retrieving the COM class factory for component with CLSID {000209FF-0000-0000-C000-000000000046} failed due to the following error: 80080005 Server execution failed (Exception from HRESULT: 0x80080005 (CO_E_SERVER_EXEC_FAILURE)). at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck) at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache) at System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean skipCheckThis, Boolean fillCache) at System.Activator.CreateInstance(Type type, Boolean nonPublic) at Meeho.Integration.OfficeHelper.ProcessWordDocument(String path, List`1 kvs) in C:\meeho\src\webservices\Meeho.Integration\OfficeHelper.cs:line 30 at Meeho.IntegrationService.ConvertDocument(Byte[] template, String ext, String[] fields, String[] values) in C:\meeho\src\webservices\MeehoService\IntegrationService.asmx.cs:line 49 -- I googled the COM error, but it returns nothing of particular value. I even gave the right permissions for the COM dll's using mmc -32, where I allocated the Word and Excel documents respectively and set the execution rights to the Administrator. I could not, however, locate the dll's by the exact COM CLSID given above. Very frustrating. Please, please, please help me as the application is currently pulled out of production. Anders EDIT: output from the Windows event log: Faulting application name: WINWORD.EXE, version: 12.0.6514.5000, time stamp: 0x4a89d533 Faulting module name: unknown, version: 0.0.0.0, time stamp: 0x00000000 Exception code: 0xc0000005 Fault offset: 0x00000000 Faulting process id: 0x720 Faulting application start time: 0x01cac571c4f82a7b Faulting application path: C:\Program Files (x86)\Microsoft Office\Office12\WINWORD.EXE Faulting module path: unknown Report Id: 041dd5f9-3165-11df-b96a-0025643cefe6 - 1000 2 100 0x80000000000000 2963 Application meeho3 - WINWORD.EXE 12.0.6514.5000 4a89d533 unknown 0.0.0.0 00000000 c0000005 00000000 720 01cac571c4f82a7b C:\Program Files (x86)\Microsoft Office\Office12\WINWORD.EXE unknown 041dd5f9-3165-11df-b96a-0025643cefe6

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• Point in polygon OR point on polygon using LINQ

  - by wageoghe

  As noted in an earlier question, How to Zip enumerable with itself, I am working on some math algorithms based on lists of points. I am currently working on point in polygon. I have the code for how to do that and have found several good references here on SO, such as this link Hit test. So, I can figure out whether or not a point is in a polygon. As part of determining that, I want to determine if the point is actually on the polygon. This I can also do. If I can do all of that, what is my question you might ask? Can I do it efficiently using LINQ? I can already do something like the following (assuming a Pairwise extension method as described in my earlier question as well as in links to which my question/answers links, and assuming a Position type that has X and Y members). I have not tested much, so the lambda might not be 100% correct. Also, it does not take very small differences into account. public static PointInPolygonLocation PointInPolygon(IEnumerable<Position> pts, Position pt) { int numIntersections = pts.Pairwise( (p1, p2) => { if (p1.Y != p2.Y) { if ((p1.Y >= pt.Y && p2.Y < pt.Y) || (p1.Y < pt.Y && p2.Y >= pt.Y)) { if (p1.X < p1.X && p2.X < pt.X) { return 1; } if (p1.X < pt.X || p2.X < pt.X) { if (((pt.Y - p1.Y) * ((p1.X - p2.X) / (p1.Y - p2.Y)) * p1.X) < pt.X) { return 1; } } } } return 0; }).Sum(); if (numIntersections % 2 == 0) { return PointInPolygonLocation.Outside; } else { return PointInPolygonLocation.Inside; } } This function, PointInPolygon, takes the input Position, pt, iterates over the input sequence of position values, and uses the Jordan Curve method to determine how many times a ray extended from pt to the left intersects the polygon. The lambda expression will yield, into the "zipped" list, 1 for every segment that is crossed, and 0 for the rest. The sum of these values determines if pt is inside or outside of the polygon (odd == inside, even == outside). So far, so good. Now, for any consecutive pairs of position values in the sequence (i.e. in any execution of the lambda), we can also determine if pt is ON the segment p1, p2. If that is the case, we can stop the calculation because we have our answer. Ultimately, my question is this: Can I perform this calculation (maybe using Aggregate?) such that we will only iterate over the sequence no more than 1 time AND can we stop the iteration if we encounter a segment that pt is ON? In other words, if pt is ON the very first segment, there is no need to examine the rest of the segments because we have the answer. It might very well be that this operation (particularly the requirement/desire to possibly stop the iteration early) does not really lend itself well to the LINQ approach. It just occurred to me that maybe the lambda expression could yield a tuple, the intersection value (1 or 0 or maybe true or false) and the "on" value (true or false). Maybe then I could use TakeWhile(anontype.PointOnPolygon == false). If I Sum the tuples and if ON == 1, then the point is ON the polygon. Otherwise, the oddness or evenness of the sum of the other part of the tuple tells if the point is inside or outside.

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• MVC 2 Ajax.Beginform passes returned Html to javascript function

  - by Joe

  Hi, I have a small partial Create Person form in a page above a table of results. I want to be able to post the form to the server, which I can do no problem with ajax.Beginform. <% using (Ajax.BeginForm("Create", new AjaxOptions { OnComplete = "ProcessResponse" })) {%> <fieldset> <legend>Fields</legend> <div class="editor-label"> <%=Html.LabelFor(model => model.FirstName)%> </div> <div class="editor-field"> <%=Html.TextBoxFor(model => model.FirstName)%> <%=Html.ValidationMessageFor(model => model.FirstName)%> </div> <div class="editor-label"> <%=Html.LabelFor(model => model.LastName)%> </div> <div class="editor-field"> <%=Html.TextBoxFor(model => model.LastName)%> <%=Html.ValidationMessageFor(model => model.LastName)%> </div> <p> <input type="submit" /> </p> </fieldset> <% } %> Then in my controller I want to be able to post back a partial which is just a table row if the create is successful and append it to the table, which I can do easily with jquery. $('#personTable tr:last').after(data); However, if server validation fails I want to pass back my partial create person form with the validation errors and replace the existing Create Person form. I have tried returning a Json array Controller: return Json(new { Success = true, Html= this.RenderViewToString("PersonSubform",person) }); Javascript: var json_data = response.get_response().get_object(); with a pass/fail flag and the partial rendered as a string using the solition below but that doesnt render the mvc validation controls when the form fails. SO RenderPartialToString So, is there any way I can hand my javascript the out of the box PartialView("PersonForm") as its returned from my ajax.form? Can I pass some addition info as a Json array so I can tell if its pass or fail and maybe add a message? UPDATE I can now pass the HTML of a PartialView to my javascript but I need to pass some additional data pairs like ServerValidation : true/false and ActionMessage : "you have just created a Person Bill". Ideally I would pass a Json array rather than hidden fields in my partial. function ProcessResponse(response) { var html = response.get_data(); $("#campaignSubform").html(html); } Many thanks in advance

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• Lightning talk: Coderetreat

  - by Michael Williamson

  In the spirit of trying to encourage more deliberate practice amongst coders in Red Gate, Lauri Pesonen had the idea of running a coderetreat in Red Gate. Lauri and I ran the first one a few weeks ago: given that neither of us hadn’t even been to a coderetreat before, let alone run one, I think it turned out quite well. The participants gave positive feedback, saying that they enjoyed the day, wrote some thought-provoking code and would do it again. Sam Blackburn was one of the attendees, and gave a lightning talk to the other developers in one of our regular lightning talk sessions: In case you can’t watch the video, I’ve transcribed the talk below, although I’d recommend watching the video if you can — I didn’t have much time to do the transcribing! So, what is a coderetreat? So it’s not just something in Red Gate, there’s a website and everything, although it’s not a very big website. It calls itself a community network. The basic ideas behind coderetreat are: you’ve got one day, and you split it into one hour sections. You spend three quarters of that coding, and do a little retrospective at the end. You’re supposed to start fresh each, we were told to delete our code after every session. We were in pairs, swapping after each session, and we did the same task every time. In fact, Conway’s Game of Life is the only task mentioned anywhere that I find for coderetreat. So I don’t know what we’ll do next time, or if we’re meant to do the same thing again. There are some guiding principles which felt to us like restrictions, that you have to code in crazy ways to encourage better code. Final thing is that it’s supposed to be free for outsiders to join. It’s meant to be a kind of networking thing, where you link up with people from other companies. We had a pilot day with Michael and Lauri. Since it was basically the first time any of us had done anything like this, everybody was from Red Gate. We didn’t chat to anybody else for the initial one. The task was Conway’s Game of Life, which most of you have probably heard of it, all but one of us knew about it when did the coderetreat. I won’t got into the details of what it is, but it felt like the right size of task, basically one or two groups actually produced something working by the end of the day, and of course that doesn’t mean it’s necessarily a day’s work to produce that because we were starting again every hour. The task really drives you more than trying to create good code, I found. It was really tempting to try and get it working rather than stick to the rules. But it’s really good to stop and try again because there are so many what-ifs when you’ve finished writing something, “what if I’d done it this way?”. You can answer all those questions at a coderetreat because it’s not about getting a product out the door, it’s about learning and playing with ideas. So we had all these different practices we were trying. I’ll try and go through most of these. Single responsibility is this idea that everything should do just one thing. It was the very first session, we were still trying to figure out how do you go about the Game of Life? So by the end of forty-five minutes hadn’t produced very much for that first session. We were still thinking, “Do we start with a board, how do we represent all these squares? It can be infinitely big, help, this is getting really difficult!”. So, most of us didn’t really get anywhere on the first one. Although it was interesting that some people started with the board, one group started with the FateDecider class that decides whether things live or die. A sort of god class, but in a good way. They managed to implement all of the rules without even defining how the squares were arranged or anything like that. Another thing we tried was TDD (test-driven development). I’m sure most of you know what TDD is: Watch a test, watch it fail for the right reason Write code to pass the test, watch it pass Refactor, check the test still passes Repeat! It basically worked, we were able to produce code, but we often found the tests defined the direction that code went, which is obviously the idea of TDD. But you tend to find that by the time you’ve even written your first assertion, which is supposed to be the very first thing you write, because you write your tests backwards from the assertions back to the initial conditions, you’ve already constrained the logic of the code in some way by the time you’ve done that. You then get to this situation of, “Well, we actually want to go in a slightly different direction. Can we do this?”. Can we write tests that don’t constrain the architecture? Wrapping up all primitives: it’s kind of turtles all the way down. We had a Size, which has a Width and Height, which both derive from Dimension. You’ve got pages of code before you’ve even done anything. No getters and setters (use tell don’t ask instead): mocks and stubs for tests are required if you want to assert that your results are what you think they should be. You can’t just check the internal state of the code. And people found that really challenging and it made them think in a different way which I think is really good. Not having mutable state: that was kind of confusing because we weren’t quite sure what fitted within that rule and what didn’t, and I think we were trying too hard to follow the rule rather than the guideline. No if-statements: supposed to use polymorphism instead, but polymorphism still requires a factory with conditional behaviour. We did something really crazy to get around this: public T If(bool condition, Func<T> left, Func<T> right) { var dict = new Dictionary<bool, Func<T>> {{true, left}, {false, right}}; return dict[condition].Invoke(); } That is not really polymorphism, is it? For-loops: you can always replace a for-loop with recursion, but it doesn’t tend to make it any more readable unless it’s the kind of task that really lends itself to that. So it was interesting, it was good practice, but it wouldn’t make it easier it’s the kind of tree-structure algorithm where that would help. Having a limit on the number of levels of indentation: again, I think it does produce very nice, clean code, but it wasn’t actually a challenge because you just extract methods. That’s quite a useful thing because you can apply that to real code and say, “Okay, should this method really be going crazy like this?” No talking: we hated that. It’s like there’s two of you at a computer, and one of you is doing the typing, what does the other guy do if they’re not allowed to talk. The answer is TDD ping-pong – one person writes the tests, and then the other person writes the code to pass the test. And that creates communication without actually having to have discussion about things which is kind of cool. No code comments: just makes no difference to anything. It’s a forty-five minute exercise, so what are you going to put comments in code for? Finally, this is my fault. I discovered an entertaining way of doing the calculation that was kind of cool (using convolutions over the state of the board). Unfortunately, it turns out to be really hard to implement in C#, so didn’t even manage to work out how to do that convolution in C#. It’s trivial in some high-level languages, but you need something matrix-orientated for it to really work. That’s most of it, really. The thoughts that people went away with: we put down our answers to questions like “What have you learnt?” and “What surprised you?”, “How are you going to do things differently?”, and most people said redoing the problem is really, really good for understanding it properly. People hate having a massive legacy codebase that they can’t change, so being able to attack something three different ways in an environment where the end-product isn’t important: that’s something people really enjoyed. Pair-programming: also people said that they wanted to do more of that, especially with TDD ping-pong, where you write the test and somebody else writes the code. Various people thought different things about immutables, but most people thought they were good, they promote functional programming. And TDD people found really hard. “Tell, don’t ask” people found really, really hard and really, really, really hard to do well. And the recursion just made things trickier to debug. But most people agreed that coderetreats are really cool, and we should do more of them.

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• Professional Scrum Developer (.NET) Training in London

  - by Martin Hinshelwood

  On the 26th - 30th July in Microsoft’s offices in London Adam Cogan from SSW will be presenting the first Professional Scrum Developer course in the UK. I will be teaching this course along side Adam and it is a fantastic experience. You are split into teams and go head-to-head to deliver units of potentially shippable work in four two hour sprints. The Professional Scrum Developer course is the only course endorsed by both Microsoft and Ken Schwaber and they have worked together very effectively in brining this course to fruition. This course is the brain child of Richard Hundhausen, a Microsoft Regional Director, and both Adam and I attending the Trainer Prep in Sydney when he was there earlier this year. He is a fantastic trainer and no matter where you do this course you can be safe in the knowledge that he has trained and vetted all of the teachers. A tools version of Ken if you will Find a course and register Download this syllabus Download the Scrum Guide What is the Professional Scrum Developer course all about? Professional Scrum Developer course is a unique and intensive five-day experience for software developers. The course guides teams on how to turn product requirements into potentially shippable increments of software using the Scrum framework, Visual Studio 2010, and modern software engineering practices. Attendees will work in self-organizing, self-managing teams using a common instance of Team Foundation Server 2010. Who should attend this course? This course is suitable for any member of a software development team – architect, programmer, database developer, tester, etc. Entire teams are encouraged to attend and experience the course together, but individuals are welcome too. Attendees will self-organize to form cross-functional Scrum teams. These teams require an aggregate of skills specific to the selected case study. Please see the last page of this document for specific details. Product Owners, ScrumMasters, and other stakeholders are welcome too, but keep in mind that everyone who attends will be expected to commit to work and pull their weight on a Scrum team. What should you know by the end of the course? Scrum will be experienced through a combination of lecture, demonstration, discussion, and hands-on exercises. Attendees will learn how to do Scrum correctly while being coached and critiqued by the instructor, in the following topic areas: Form effective teams Explore and understand legacy “Brownfield” architecture Define quality attributes, acceptance criteria, and “done” Create automated builds How to handle software hotfixes Verify that bugs are identified and eliminated Plan releases and sprints Estimate product backlog items Create and manage a sprint backlog Hold an effective sprint review Improve your process by using retrospectives Use emergent architecture to avoid technical debt Use Test Driven Development as a design tool Setup and leverage continuous integration Use Test Impact Analysis to decrease testing times Manage SQL Server development in an Agile way Use .NET and T-SQL refactoring effectively Build, deploy, and test SQL Server databases Create and manage test plans and cases Create, run, record, and play back manual tests Setup a branching strategy and branch code Write more maintainable code Identify and eliminate people and process dysfunctions Inspect and improve your team’s software development process What does the week look like? This course is a mix of lecture, demonstration, group discussion, simulation, and hands-on software development. The bulk of the course will be spent working as a team on a case study application delivering increments of new functionality in mini-sprints. Here is the week at a glance: Monday morning and most of the day Friday will be spent with the computers powered off, so you can focus on sharpening your game of Scrum and avoiding the common pitfalls when implementing it. The Sprints Timeboxing is a critical concept in Scrum as well as in this course. We expect each team and student to understand and obey all of the timeboxes. The timebox duration will always be clearly displayed during each activity. Expect the instructor to enforce it. Each of the ½ day sprints will roughly follow this schedule: Component Description Minutes Instruction Presentation and demonstration of new and relevant tools & practices 60 Sprint planning meeting Product owner presents backlog; each team commits to delivering functionality 10 Sprint planning meeting Each team determines how to build the functionality 10 The Sprint The team self-organizes and self-manages to complete their tasks 120 Sprint Review meeting Each team will present their increment of functionality to the other teams = 30 Sprint Retrospective A group retrospective meeting will be held to inspect and adapt 10 Each team is expected to self-organize and manage their own work during the sprint. Pairing is highly encouraged. The instructor/product owner will be available if there are questions or impediments, but will be hands-off by default. You should be prepared to communicate and work with your team members in order to achieve your sprint goal. If you have development-related questions or get stuck, your partner or team should be your first level of support. Module 1: INTRODUCTION This module provides a chance for the attendees to get to know the instructors as well as each other. The Professional Scrum Developer program, as well as the day by day agenda, will be explained. Finally, the Scrum team will be selected and assembled so that the forming, storming, norming, and performing can begin. Trainer and student introductions Professional Scrum Developer program Agenda Logistics Team formation Retrospective Module 2: SCRUMDAMENTALS This module provides a level-setting understanding of the Scrum framework including the roles, timeboxes, and artifacts. The team will then experience Scrum firsthand by simulating a multi-day sprint of product development, including planning, review, and retrospective meetings. Scrum overview Scrum roles Scrum timeboxes (ceremonies) Scrum artifacts Simulation Retrospective It’s required that you read Ken Schwaber’s Scrum Guide in preparation for this module and course. MODULE 3: IMPLEMENTING SCRUM IN VISUAL STUDIO 2010 This module demonstrates how to implement Scrum in Visual Studio 2010 using a Scrum process template*. The team will learn the mapping between the Scrum concepts and how they are implemented in the tool. After connecting to the shared Team Foundation Server, the team members will then return to the simulation – this time using Visual Studio to manage their product development. Mapping Scrum to Visual Studio 2010 User Story work items Task work items Bug work items Demonstration Simulation Retrospective Module 4: THE CASE STUDY In this module the team is introduced to their problem domain for the week. A kickoff meeting by the Product Owner (the instructor) will set the stage for the why and what that will take during the upcoming sprints. The team will then define the quality attributes of the project and their definition of “done.” The legacy application code will be downloaded, built, and explored, so that any bugs can be discovered and reported. Introduction to the case study Download the source code, build, and explore the application Define the quality attributes for the project Define “done” How to file effective bugs in Visual Studio 2010 Retrospective Module 5: HOTFIX This module drops the team directly into a Brownfield (legacy) experience by forcing them to analyze the existing application’s architecture and code in order to locate and fix the Product Owner’s high-priority bug(s). The team will learn best practices around finding, testing, fixing, validating, and closing a bug. How to use Architecture Explorer to visualize and explore Create a unit test to validate the existence of a bug Find and fix the bug Validate and close the bug Retrospective Module 6: PLANNING This short module introduces the team to release and sprint planning within Visual Studio 2010. The team will define and capture their goals as well as other important planning information. Release vs. Sprint planning Release planning and the Product Backlog Product Backlog prioritization Acceptance criteria and tests Sprint planning and the Sprint Backlog Creating and linking Sprint tasks Retrospective At this point the team will have the knowledge of Scrum, Visual Studio 2010, and the case study application to begin developing increments of potentially shippable functionality that meet their definition of done. Module 7: EMERGENT ARCHITECTURE This module introduces the architectural practices and tools a team can use to develop a valid design on which to develop new functionality. The teams will learn how Scrum supports good architecture and design practices. After the discussion, the teams will be presented with the product owner’s prioritized backlog so that they may select and commit to the functionality they can deliver in this sprint. Architecture and Scrum Emergent architecture Principles, patterns, and practices Visual Studio 2010 modeling tools UML and layer diagrams SPRINT 1 Retrospective Module 8: TEST DRIVEN DEVELOPMENT This module introduces Test Driven Development as a design tool and how to implement it using Visual Studio 2010. To maximize productivity and quality, a Scrum team should setup Continuous Integration to regularly build every team member’s code changes and run regression tests. Refactoring will also be defined and demonstrated in combination with Visual Studio’s Test Impact Analysis to efficiently re-run just those tests which were impacted by refactoring. Continuous integration Team Foundation Build Test Driven Development (TDD) Refactoring Test Impact Analysis SPRINT 2 Retrospective Module 9: AGILE DATABASE DEVELOPMENT This module lets the SQL Server database developers in on a little secret – they can be agile too. By using the database projects in Visual Studio 2010, the database developers can join the rest of the team. The students will see how to apply Agile database techniques within Visual Studio to support the SQL Server 2005/2008/2008R2 development lifecycle. Agile database development Visual Studio database projects Importing schema and scripts Building and deploying Generating data Unit testing SPRINT 3 Retrospective Module 10: SHIP IT Teams need to know that just because they like the functionality doesn’t mean the Product Owner will. This module revisits acceptance criteria as it pertains to acceptance testing. By refining acceptance criteria into manual test steps, team members can execute the tests, recording the results and reporting bugs in a number of ways. Manual tests will be defined and executed using the Microsoft Test Manager tool. As the Sprint completes and an increment of functionality is delivered, the team will also learn why and when they should create a branch of the codeline. Acceptance criteria Testing in Visual Studio 2010 Microsoft Test Manager Writing and running manual tests Branching SPRINT 4 Retrospective Module 11: OVERCOMING DYSFUNCTION This module introduces the many types of people, process, and tool dysfunctions that teams face in the real world. Many dysfunctions and scenarios will be identified, along with ideas and discussion for how a team might mitigate them. This module will enable you and your team to move toward independence and improve your game of Scrum when you depart class. Scrum-butts and flaccid Scrum Best practices working as a team Team challenges ScrumMaster challenges Product Owner challenges Stakeholder challenges Course Retrospective What will be expected of you and you team? This is a unique course in that it’s technically-focused, team-based, and employs timeboxes. It demands that the members of the teams self-organize and self-manage their own work to collaboratively develop increments of software. All attendees must commit to: Pay attention to all lectures and demonstrations Participate in team and group discussions Work collaboratively with other team members Obey the timebox for each activity Commit to work and do your best to deliver All teams should have these skills: Understanding of Scrum Familiarity with Visual Studio 201 C#, .NET 4.0 & ASP.NET 4.0 experience*  SQL Server 2008 development experience Software testing experience * Check with the instructor ahead of time for the exact technologies Self-organising teams Another unique attribute of this course is that it’s a technical training class being delivered to teams of developers, not pairs, and not individuals. Ideally, your actual software development team will attend the training to ensure that all necessary skills are covered. However, if you wish to attend an open enrolment course alone or with just a couple of colleagues, realize that you may be placed on a team with other attendees. The instructor will do his or her best to ensure that each team is cross-functional to tackle the case study, but there are no guarantees. You may be required to try a new role, learn a new skill, or pair with somebody unfamiliar to you. This is just good Scrum! Who should NOT take this course? Because of the nature of this course, as explained above, certain types of people should probably not attend this course: Students requiring command and control style instruction – there are no prescriptive/step-by-step (think traditional Microsoft Learning) labs in this course Students who are unwilling to work within a timebox Students who are unwilling to work collaboratively on a team Students who don’t have any skill in any of the software development disciplines Students who are unable to commit fully to their team – not only will this diminish the student’s learning experience, but it will also impact their team’s learning experience Find a course and register Download this syllabus Download the Scrum Guide Technorati Tags: Scrum,SSW,Pro Scrum Dev

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• How I Work: A Cloud Developer's Workstation

  - by BuckWoody

  I've written here a little about how I work during the day, including things like using a stand-up desk (still doing that, by the way). Inspired by a Twitter conversation yesterday, I thought I might explain how I set up my computing environment. First, a couple of important points. I work in Cloud Computing, specifically (but not limited to) Windows Azure. Windows Azure has features to run a Virtual Machine (IaaS), run code without having to control a Virtual Machine (PaaS) and use databases, video streaming, Hadoop and more (a kind of SaaS for tech pros). As such, my designs run the gamut of on-premises, VM's in the Cloud, and software that I write for a platform. I focus on data primarily, meaning that I design a lot of systems that use an RDBMS (like SQL Server or Windows Azure Databases) or a NoSQL approach (MongoDB on Azure or large-scale Key-Value Pairs in Table storage) and even Hadoop and R, and also Cloud Numerics in F#. All that being said, those things inform my choices below. Hardware I have a Lenovo X220 tablet/laptop which I really like a great deal - it's a light, tough, extremely fast system. When I travel, that's the system I take. It has 8GB of RAM, and an SSD drive. I sometimes use that to develop or work at a client's site, on the road, or in the living room when I'm not in my home office. My main system is a GateWay DX430017 - I've maxed it out on RAM, and I have two 1TB drives in it. It's not only my workstation for work; I leave it on all the time and it streams our videos, music and books. I have about 3400 e-books, and I've just started using Calibre to stream the library. I run Windows 8 on it so I can set up Hyper-V images, since Windows Azure allows me to move regular Hyper-V disks back and forth to the Cloud. That's where all my "servers" are, when I have to use an IaaS approach. The reason I use a desktop-style system rather than a laptop only approach is that a good part of my job is setting up architectures to solve really big, complex problems. That means I have to simulate entire networks on-premises, along with the Hybrid Cloud approach I use a lot. I need a lot of disk space and memory for that, and I use two huge monitors on my stand-up desk. I could probably use 10 monitors if I had the room for them. Also, since it's our home system as well, I leave it on all the time and it doesn't travel.   Software For the software for my systems, it's important to keep in mind that I not only write code, but I design databases, teach, present, and create Linux and other environments. Windows 8 - While the jury is out for me on the new interface, the context-sensitive search, integrated everything, and speed is just hands-down the right choice. I've evaluated a server OS, Linux, even an Apple, but I just am not as efficient on those as I am with Windows 8. Visual Studio Ultimate - I develop primarily in .NET (C# and F# mostly) and I use the Team Foundation Server in the cloud, and I'm asked to do everything from UI to Services, so I need everything. Windows Azure SDK, Windows Azure Training Kit - I need the first to set up my Azure PaaS coding, and the second has all the info I need for PaaS, IaaS and SaaS. This is primarily how I get paid. :) SQL Server Developer Edition - While I might install Oracle, MySQL and Postgres on my VM's, the "outside" environment is SQL Server for an RDBMS. I install the Developer Edition because it has the same features as Enterprise Edition, and comes with all the client tools and documentation. Microsoft Office -  Even if I didn't work here, this is what I would use. I've just grown too accustomed to doing business this way to change, so my advice is always "use what works", and this does. The parts I use are: OneNote (and a Math Add-in) - I do almost everything - and I mean everything in OneNote. I can code, do high-end math, present, design, collaborate and more. All my notebooks are on my Skydrive. I can use them from any system, anywhere. If you take the time to learn this program, you'll be hooked. Excel with PowerPivot - Don't make that face. Excel is the world's database, and every Data Scientist I know - even the ones where I teach at the University of Washington - know it, use it, and love it.  Outlook - Primary communications, CRM and contact tool. I have all of my social media hooked up to it, so when I get an e-mail from you, I see everything, see all the history we've had on e-mail, find you on a map and more. Lync - I was fine with LiveMeeting, although it has it's moments. For me, the Lync client is tres-awesome. I use this throughout my day, present on it, stay in contact with colleagues and the folks on the dev team (who wish I didn't have it) and more.  PowerPoint - Once again, don't make that face. Whenever I see someone complaining about PowerPoint, I have 100% of the time found they don't know how to use it. If you suck at presenting or creating content, don't blame PowerPoint. Works great on my machine. :) Zoomit - Magnifier - On Windows 7 (and 8 as well) there's a built-in magnifier, but I install Zoomit out of habit. It enlarges the screen. If you don't use one of these tools (or their equivalent on some other OS) then you're presenting/teaching wrong, and you should stop presenting/teaching until you get them and learn how to show people what you can see on your tiny, tiny monitor. :) Cygwin - Unix for Windows. OK, that's not true, but it's mostly that. I grew up on mainframes and Unix (IBM and HP, thank you) and I can't imagine life without  sed, awk, grep, vim, and bash. I also tend to take a lot of the "Science" and "Development" and "Database" packages in it as well. PuTTY - Speaking of Unix, when I need to connect to my Linux VM's in Windows Azure, I want to do it securely. This is the tool for that. Notepad++ - Somewhere between torturing myself in vim and luxuriating in OneNote is Notepad++. Everyone has a favorite text editor; this one is mine. Too many features to name, and it's free. Browsers - I install Chrome, Firefox and of course IE. I know it's in vogue to rant on IE, but I tend to think for myself a great deal, and I've had few (none) problems with it. The others I have for the haterz that make sites that won't run in IE. Visio - I've used a lot of design packages, but none have the extreme meta-data edit capabilities of Visio. I don't use this all the time - it can be rather heavy, but what it does it does really well. I also present this way when I'm not using PowerPoint. Yup, I just bring up Visio and diagram away as I'm chatting with clients. Depending on what we're covering, this can be the right tool for that. Tweetdeck - The AIR one, not that new disaster they came out with. I live on social media, since you, dear readers, are my cube-mates. When I get tired of you all, I close Tweetdeck. When I need help or someone needs help from me, or if I want to see a picture of a cat while I'm coding, I bring it up. It's up most all day and night. Windows Media Player - I listen to Trance or Classical when I code, and I find music managers overbearing and extra. I just use what comes in the box, and it works great for me. R - F# and Cloud Numerics now allows me to load in R libraries (yay!) and I use this for statistical work on big data loads. Microsoft Math - One of the most amazing, free, rich, amazing, awesome, amazing calculators out there. I get the 64-bit version for quick math conversions, plots and formula-checks. Python - I know, right? Who knew that the scientific community loved Python so much. But they do. I use 2.7; not as much runs with 3+. I also use IronPython in Visual Studio, or I edit in Notepad++ Camstudio recorder - Windows PSR - In much of my training, and all of my teaching at the UW, I need to show a process on a screen. Camstudio records screen and voice, and it's free. If I need to make static training, I use the Windows PSR tool that's built right in. It's ostensibly for problem duplication, but I use it to record for training.   OK - your turn. Post a link to your blog entry below, and tell me how you set your system up.  

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• Set-Cookie Headers getting stripped in ASP.NET HttpHandlers

  - by Rick Strahl

  Yikes, I ran into a real bummer of an edge case yesterday in one of my older low level handler implementations (for West Wind Web Connection in this case). Basically this handler is a connector for a backend Web framework that creates self contained HTTP output. An ASP.NET Handler captures the full output, and then shoves the result down the ASP.NET Response object pipeline writing out the content into the Response.OutputStream and seperately sending the HttpHeaders in the Response.Headers collection. The headers turned out to be the problem and specifically Http Cookies, which for some reason ended up getting stripped out in some scenarios. My handler works like this: Basically the HTTP response from the backend app would return a full set of HTTP headers plus the content. The ASP.NET handler would read the headers one at a time and then dump them out via Response.AppendHeader(). But I found that in some situations Set-Cookie headers sent along were simply stripped inside of the Http Handler. After a bunch of back and forth with some folks from Microsoft (thanks Damien and Levi!) I managed to pin this down to a very narrow edge scenario. It's easiest to demonstrate the problem with a simple example HttpHandler implementation. The following simulates the very much simplified output generation process that fails in my handler. Specifically I have a couple of headers including a Set-Cookie header and some output that gets written into the Response object.using System.Web; namespace wwThreads { public class Handler : IHttpHandler { /* NOTE: * * Run as a web.config set handler (see entry below) * * Best way is to look at the HTTP Headers in Fiddler * or Chrome/FireBug/IE tools and look for the * WWHTREADSID cookie in the outgoing Response headers * ( If the cookie is not there you see the problem! ) */ public void ProcessRequest(HttpContext context) { HttpRequest request = context.Request; HttpResponse response = context.Response; // If ClearHeaders is used Set-Cookie header gets removed! // if commented header is sent... response.ClearHeaders(); response.ClearContent(); // Demonstrate that other headers make it response.AppendHeader("RequestId", "asdasdasd"); // This cookie gets removed when ClearHeaders above is called // When ClearHEaders is omitted above the cookie renders response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); // *** This always works, even when explicit // Set-Cookie above fails and ClearHeaders is called //response.Cookies.Add(new HttpCookie("WWTHREADSID", "ThisIsTheValue")); response.Write(@"Output was created.<hr/> Check output with Fiddler or HTTP Proxy to see whether cookie was sent."); } public bool IsReusable { get { return false; } } } } In order to see the problem behavior this code has to be inside of an HttpHandler, and specifically in a handler defined in web.config with: <add name=".ck_handler" path="handler.ck" verb="*" type="wwThreads.Handler" preCondition="integratedMode" /> Note: Oddly enough this problem manifests only when configured through web.config, not in an ASHX handler, nor if you paste that same code into an ASPX page or MVC controller. What's the problem exactly? The code above simulates the more complex code in my live handler that picks up the HTTP response from the backend application and then peels out the headers and sends them one at a time via Response.AppendHeader. One of the headers in my app can be one or more Set-Cookie. I found that the Set-Cookie headers were not making it into the Response headers output. Here's the Chrome Http Inspector trace: Notice, no Set-Cookie header in the Response headers! Now, running the very same request after removing the call to Response.ClearHeaders() command, the cookie header shows up just fine: As you might expect it took a while to track this down. At first I thought my backend was not sending the headers but after closer checks I found that indeed the headers were set in the backend HTTP response, and they were indeed getting set via Response.AppendHeader() in the handler code. Yet, no cookie in the output. In the simulated example the problem is this line:response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); which in my live code is more dynamic ( ie. AppendHeader(token[0],token[1[]) )as it parses through the headers. Bizzaro Land: Response.ClearHeaders() causes Cookie to get stripped Now, here is where it really gets bizarre: The problem occurs only if: Response.ClearHeaders() was called before headers are added It only occurs in Http Handlers declared in web.config Clearly this is an edge of an edge case but of course - knowing my relationship with Mr. Murphy - I ended up running smack into this problem. So in the code above if you remove the call to ClearHeaders(), the cookie gets set!  Add it back in and the cookie is not there. If I run the above code in an ASHX handler it works. If I paste the same code (with a Response.End()) into an ASPX page, or MVC controller it all works. Only in the HttpHandler configured through Web.config does it fail! Cue the Twilight Zone Music. Workarounds As is often the case the fix for this once you know the problem is not too difficult. The difficulty lies in tracking inconsistencies like this down. Luckily there are a few simple workarounds for the Cookie issue. Don't use AppendHeader for Cookies The easiest and obvious solution to this problem is simply not use Response.AppendHeader() to set Cookies. Duh! Under normal circumstances in application level code there's rarely a reason to write out a cookie like this:response.AppendHeader("Set-Cookie", "WWTHREADSID=ThisIsThEValue; path=/"); but rather create the cookie using the Response.Cookies collection:response.Cookies.Add(new HttpCookie("WWTHREADSID", "ThisIsTheValue")); Unfortunately, in my case where I dynamically read headers from the original output and then dynamically  write header key value pairs back  programmatically into the Response.Headers collection, I actually don't look at each header specifically so in my case the cookie is just another header. My first thought was to simply trap for the Set-Cookie header and then parse out the cookie and create a Cookie object instead. But given that cookies can have a lot of different options this is not exactly trivial, plus I don't really want to fuck around with cookie values which can be notoriously brittle. Don't use Response.ClearHeaders() The real mystery in all this is why calling Response.ClearHeaders() prevents a cookie value later written with Response.AppendHeader() to fail. I fired up Reflector and took a quick look at System.Web and HttpResponse.ClearHeaders. There's all sorts of resetting going on but nothing that seems to indicate that headers should be removed later on in the request. The code in ClearHeaders() does access the HttpWorkerRequest, which is the low level interface directly into IIS, and so I suspect it's actually IIS that's stripping the headers and not ASP.NET, but it's hard to know. Somebody from Microsoft and the IIS team would have to comment on that. In my application it's probably safe to simply skip ClearHeaders() in my handler. The ClearHeaders/ClearContent was mainly for safety but after reviewing my code there really should never be a reason that headers would be set prior to this method firing. However, if for whatever reason headers do need to be cleared, it's easy enough to manually clear the headers out:private void RemoveHeaders(HttpResponse response) { List<string> headers = new List<string>(); foreach (string header in response.Headers) { headers.Add(header); } foreach (string header in headers) { response.Headers.Remove(header); } response.Cookies.Clear(); } Now I can replace the call the Response.ClearHeaders() and I don't get the funky side-effects from Response.ClearHeaders(). Summary I realize this is a total edge case as this occurs only in HttpHandlers that are manually configured. It looks like you'll never run into this in any of the higher level ASP.NET frameworks or even in ASHX handlers - only web.config defined handlers - which is really, really odd. After all those frameworks use the same underlying ASP.NET architecture. Hopefully somebody from Microsoft has an idea what crazy dependency was triggered here to make this fail. IAC, there are workarounds to this should you run into it, although I bet when you do run into it, it'll likely take a bit of time to find the problem or even this post in a search because it's not easily to correlate the problem to the solution. It's quite possible that more than cookies are affected by this behavior. Searching for a solution I read a few other accounts where headers like Referer were mysteriously disappearing, and it's possible that something similar is happening in those cases. Again, extreme edge case, but I'm writing this up here as documentation for myself and possibly some others that might have run into this. © Rick Strahl, West Wind Technologies, 2005-2012Posted in ASP.NET   IIS7   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Sharing the model in MVP Winforms App

  - by Keith G

  I'm working on building up an MVP application (C# Winforms). My initial version is at http://stackoverflow.com/questions/1422343/ ... Now I'm increasing the complexity. I've broken out the code to handle two separate text fields into two view/presenter pairs. It's a trivial example, but it's to work out the details of multiple presenters sharing the same model. My questions are about the model: I am basically using a property changed event raised by the model for notifying views that something has changed. Is that a good approach? What if it gets to the point where I have 100 or 1000 properties? Is it still practical at that point? Is instantiating the model in each presenter with   NoteModel _model = NoteModel.Instance   the correct approach? Note that I do want to make sure all of the presenters are sharing the same data. If there is a better approach, I'm open to suggestions .... My code looks like this: NoteModel.cs public class NoteModel : INotifyPropertyChanged { private static NoteModel _instance = null; public static NoteModel Instance { get { return _instance; } } static NoteModel() { _instance = new NoteModel(); } private NoteModel() { Initialize(); } public string Filename { get; set; } public bool IsDirty { get; set; } public readonly string DefaultName = "Untitled.txt"; string _sText; public string TheText { get { return _sText; } set { _sText = value; PropertyHasChanged("TheText"); } } string _sMoreText; public string MoreText { get { return _sMoreText; } set { _sMoreText = value; PropertyHasChanged("MoreText"); } } public void Initialize() { Filename = DefaultName; TheText = String.Empty; MoreText = String.Empty; IsDirty = false; } private void PropertyHasChanged(string sPropName) { IsDirty = true; if (PropertyChanged != null) { PropertyChanged(this, new PropertyChangedEventArgs(sPropName)); } } public event PropertyChangedEventHandler PropertyChanged; } TextEditorPresenter.cs public class TextEditorPresenter { ITextEditorView _view; NoteModel _model = NoteModel.Instance; public TextEditorPresenter(ITextEditorView view)//, NoteModel model) { //_model = model; _view = view; _model.PropertyChanged += new PropertyChangedEventHandler(model_PropertyChanged); } void model_PropertyChanged(object sender, PropertyChangedEventArgs e) { if (e.PropertyName == "TheText") _view.TheText = _model.TheText; } public void TextModified() { _model.TheText = _view.TheText; } public void ClearView() { _view.TheText = String.Empty; } } TextEditor2Presenter.cs is essentially the same except it operates on _model.MoreText instead of _model.TheText. ITextEditorView.cs public interface ITextEditorView { string TheText { get; set; } } ITextEditor2View.cs public interface ITextEditor2View { string MoreText { get; set; } }

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• Understanding C# async / await (2) Awaitable / Awaiter Pattern

  - by Dixin

  What is awaitable Part 1 shows that any Task is awaitable. Actually there are other awaitable types. Here is an example: Task<int> task = new Task<int>(() => 0); int result = await task.ConfigureAwait(false); // Returns a ConfiguredTaskAwaitable<TResult>. The returned ConfiguredTaskAwaitable<TResult> struct is awaitable. And it is not Task at all: public struct ConfiguredTaskAwaitable<TResult> { private readonly ConfiguredTaskAwaiter m_configuredTaskAwaiter; internal ConfiguredTaskAwaitable(Task<TResult> task, bool continueOnCapturedContext) { this.m_configuredTaskAwaiter = new ConfiguredTaskAwaiter(task, continueOnCapturedContext); } public ConfiguredTaskAwaiter GetAwaiter() { return this.m_configuredTaskAwaiter; } } It has one GetAwaiter() method. Actually in part 1 we have seen that Task has GetAwaiter() method too: public class Task { public TaskAwaiter GetAwaiter() { return new TaskAwaiter(this); } } public class Task<TResult> : Task { public new TaskAwaiter<TResult> GetAwaiter() { return new TaskAwaiter<TResult>(this); } } Task.Yield() is a another example: await Task.Yield(); // Returns a YieldAwaitable. The returned YieldAwaitable is not Task either: public struct YieldAwaitable { public YieldAwaiter GetAwaiter() { return default(YieldAwaiter); } } Again, it just has one GetAwaiter() method. In this article, we will look at what is awaitable. The awaitable / awaiter pattern By observing different awaitable / awaiter types, we can tell that an object is awaitable if It has a GetAwaiter() method (instance method or extension method); Its GetAwaiter() method returns an awaiter. An object is an awaiter if: It implements INotifyCompletion or ICriticalNotifyCompletion interface; It has an IsCompleted, which has a getter and returns a Boolean; it has a GetResult() method, which returns void, or a result. This awaitable / awaiter pattern is very similar to the iteratable / iterator pattern. Here is the interface definitions of iteratable / iterator: public interface IEnumerable { IEnumerator GetEnumerator(); } public interface IEnumerator { object Current { get; } bool MoveNext(); void Reset(); } public interface IEnumerable<out T> : IEnumerable { IEnumerator<T> GetEnumerator(); } public interface IEnumerator<out T> : IDisposable, IEnumerator { T Current { get; } } In case you are not familiar with the out keyword, please find out the explanation in Understanding C# Covariance And Contravariance (2) Interfaces. The “missing” IAwaitable / IAwaiter interfaces Similar to IEnumerable and IEnumerator interfaces, awaitable / awaiter can be visualized by IAwaitable / IAwaiter interfaces too. This is the non-generic version: public interface IAwaitable { IAwaiter GetAwaiter(); } public interface IAwaiter : INotifyCompletion // or ICriticalNotifyCompletion { // INotifyCompletion has one method: void OnCompleted(Action continuation); // ICriticalNotifyCompletion implements INotifyCompletion, // also has this method: void UnsafeOnCompleted(Action continuation); bool IsCompleted { get; } void GetResult(); } Please notice GetResult() returns void here. Task.GetAwaiter() / TaskAwaiter.GetResult() is of such case. And this is the generic version: public interface IAwaitable<out TResult> { IAwaiter<TResult> GetAwaiter(); } public interface IAwaiter<out TResult> : INotifyCompletion // or ICriticalNotifyCompletion { bool IsCompleted { get; } TResult GetResult(); } Here the only difference is, GetResult() return a result. Task<TResult>.GetAwaiter() / TaskAwaiter<TResult>.GetResult() is of this case. Please notice .NET does not define these IAwaitable / IAwaiter interfaces at all. As an UI designer, I guess the reason is, IAwaitable interface will constraint GetAwaiter() to be instance method. Actually C# supports both GetAwaiter() instance method and GetAwaiter() extension method. Here I use these interfaces only for better visualizing what is awaitable / awaiter. Now, if looking at above ConfiguredTaskAwaitable / ConfiguredTaskAwaiter, YieldAwaitable / YieldAwaiter, Task / TaskAwaiter pairs again, they all “implicitly” implement these “missing” IAwaitable / IAwaiter interfaces. In the next part, we will see how to implement awaitable / awaiter. Await any function / action In C# await cannot be used with lambda. This code: int result = await (() => 0); will cause a compiler error: Cannot await 'lambda expression' This is easy to understand because this lambda expression (() => 0) may be a function or a expression tree. Obviously we mean function here, and we can tell compiler in this way: int result = await new Func<int>(() => 0); It causes an different error: Cannot await 'System.Func<int>' OK, now the compiler is complaining the type instead of syntax. With the understanding of the awaitable / awaiter pattern, Func<TResult> type can be easily made into awaitable. GetAwaiter() instance method, using IAwaitable / IAwaiter interfaces First, similar to above ConfiguredTaskAwaitable<TResult>, a FuncAwaitable<TResult> can be implemented to wrap Func<TResult>: internal struct FuncAwaitable<TResult> : IAwaitable<TResult> { private readonly Func<TResult> function; public FuncAwaitable(Func<TResult> function) { this.function = function; } public IAwaiter<TResult> GetAwaiter() { return new FuncAwaiter<TResult>(this.function); } } FuncAwaitable<TResult> wrapper is used to implement IAwaitable<TResult>, so it has one instance method, GetAwaiter(), which returns a IAwaiter<TResult>, which wraps that Func<TResult> too. FuncAwaiter<TResult> is used to implement IAwaiter<TResult>: public struct FuncAwaiter<TResult> : IAwaiter<TResult> { private readonly Task<TResult> task; public FuncAwaiter(Func<TResult> function) { this.task = new Task<TResult>(function); this.task.Start(); } bool IAwaiter<TResult>.IsCompleted { get { return this.task.IsCompleted; } } TResult IAwaiter<TResult>.GetResult() { return this.task.Result; } void INotifyCompletion.OnCompleted(Action continuation) { new Task(continuation).Start(); } } Now a function can be awaited in this way: int result = await new FuncAwaitable<int>(() => 0); GetAwaiter() extension method As IAwaitable shows, all that an awaitable needs is just a GetAwaiter() method. In above code, FuncAwaitable<TResult> is created as a wrapper of Func<TResult> and implements IAwaitable<TResult>, so that there is a  GetAwaiter() instance method. If a GetAwaiter() extension method  can be defined for Func<TResult>, then FuncAwaitable<TResult> is no longer needed: public static class FuncExtensions { public static IAwaiter<TResult> GetAwaiter<TResult>(this Func<TResult> function) { return new FuncAwaiter<TResult>(function); } } So a Func<TResult> function can be directly awaited: int result = await new Func<int>(() => 0); Using the existing awaitable / awaiter - Task / TaskAwaiter Remember the most frequently used awaitable / awaiter - Task / TaskAwaiter. With Task / TaskAwaiter, FuncAwaitable / FuncAwaiter are no longer needed: public static class FuncExtensions { public static TaskAwaiter<TResult> GetAwaiter<TResult>(this Func<TResult> function) { Task<TResult> task = new Task<TResult>(function); task.Start(); return task.GetAwaiter(); // Returns a TaskAwaiter<TResult>. } } Similarly, with this extension method: public static class ActionExtensions { public static TaskAwaiter GetAwaiter(this Action action) { Task task = new Task(action); task.Start(); return task.GetAwaiter(); // Returns a TaskAwaiter. } } an action can be awaited as well: await new Action(() => { }); Now any function / action can be awaited: await new Action(() => HelperMethods.IO()); // or: await new Action(HelperMethods.IO); If function / action has parameter(s), closure can be used: int arg0 = 0; int arg1 = 1; int result = await new Action(() => HelperMethods.IO(arg0, arg1)); Using Task.Run() The above code is used to demonstrate how awaitable / awaiter can be implemented. Because it is a common scenario to await a function / action, so .NET provides a built-in API: Task.Run(): public class Task2 { public static Task Run(Action action) { // The implementation is similar to: Task task = new Task(action); task.Start(); return task; } public static Task<TResult> Run<TResult>(Func<TResult> function) { // The implementation is similar to: Task<TResult> task = new Task<TResult>(function); task.Start(); return task; } } In reality, this is how we await a function: int result = await Task.Run(() => HelperMethods.IO(arg0, arg1)); and await a action: await Task.Run(() => HelperMethods.IO());

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• Top 5 Developer Enabling Nuggets in MySQL 5.6

  - by Rob Young

  MySQL 5.6 is truly a better MySQL and reflects Oracle's commitment to the evolution of the most popular and widelyused open source database on the planet.  The feature-complete 5.6 release candidate was announced at MySQL Connect in late September and the production-ready, generally available ("GA") product should be available in early 2013.  While the message around 5.6 has been focused mainly on mass appeal, advanced topics like performance/scale, high availability, and self-healing replication clusters, MySQL 5.6 also provides many developer-friendly nuggets that are designed to enable those who are building the next generation of web-based and embedded applications and services. Boiling down the 5.6 feature set into a smaller set, of simple, easy to use goodies designed with developer agility in mind, these things deserve a quick look:Subquery Optimizations Using semi-JOINs and late materialization, the MySQL 5.6 Optimizer delivers greatly improved subquery performance. Specifically, the optimizer is now more efficient in handling subqueries in the FROM clause; materialization of subqueries in the FROM clause is now postponed until their contents are needed during execution. Additionally, the optimizer may add an index to derived tables during execution to speed up row retrieval. Internal tests run using the DBT-3 benchmark Query #13, shown below, demonstrate an order of magnitude improvement in execution times (from days to seconds) over previous versions. select c_name, c_custkey, o_orderkey, o_orderdate, o_totalprice, sum(l_quantity)from customer, orders, lineitemwhere o_orderkey in (                select l_orderkey                from lineitem                group by l_orderkey                having sum(l_quantity) > 313  )  and c_custkey = o_custkey  and o_orderkey = l_orderkeygroup by c_name, c_custkey, o_orderkey, o_orderdate, o_totalpriceorder by o_totalprice desc, o_orderdateLIMIT 100;What does this mean for developers?  For starters, simplified subqueries can now be coded instead of complex joins for cross table lookups: SELECT title FROM film WHERE film_id IN (SELECT film_id FROM film_actor GROUP BY film_id HAVING count(*) > 12); And even more importantly subqueries embedded in packaged applications no longer need to be re-written into joins.  This is good news for both ISVs and their customers who have access to the underlying queries and who have spent development cycles writing, testing and maintaining their own versions of re-written queries across updated versions of a packaged app.The details are in the MySQL 5.6 docs. Online DDL OperationsToday's web-based applications are designed to rapidly evolve and adapt to meet business and revenue-generationrequirements. As a result, development SLAs are now most often measured in minutes vs days or weeks. For example, when an application must quickly support new product lines or new products within existing product lines, the backend database schema must adapt in kind, and most commonly while the application remains available for normal business operations.  MySQL 5.6 supports this level of online schema flexibility and agility by providing the following new ALTER TABLE online DDL syntax additions:  CREATE INDEX DROP INDEX Change AUTO_INCREMENT value for a column ADD/DROP FOREIGN KEY Rename COLUMN Change ROW FORMAT, KEY_BLOCK_SIZE for a table Change COLUMN NULL, NOT_NULL Add, drop, reorder COLUMN Again, the details are in the MySQL 5.6 docs. Key-value access to InnoDB via Memcached APIMany of the next generation of web, cloud, social and mobile applications require fast operations against simple Key/Value pairs. At the same time, they must retain the ability to run complex queries against the same data, as well as ensure the data is protected with ACID guarantees. With the new NoSQL API for InnoDB, developers have allthe benefits of a transactional RDBMS, coupled with the performance capabilities of Key/Value store.MySQL 5.6 provides simple, key-value interaction with InnoDB data via the familiar Memcached API.  Implemented via a new Memcached daemon plug-in to mysqld, the new Memcached protocol is mapped directly to the native InnoDB API and enables developers to use existing Memcached clients to bypass the expense of query parsing and go directly to InnoDB data for lookups and transactional compliant updates.  The API makes it possible to re-use standard Memcached libraries and clients, while extending Memcached functionality by integrating a persistent, crash-safe, transactional database back-end.  The implementation is shown here:So does this option provide a performance benefit over SQL?  Internal performance benchmarks using a customized Java application and test harness show some very promising results with a 9X improvement in overall throughput for SET/INSERT operations:You can follow the InnoDB team blog for the methodology, implementation and internal test cases that generated these results here. How to get started with Memcached API to InnoDB is here. New Instrumentation in Performance SchemaThe MySQL Performance Schema was introduced in MySQL 5.5 and is designed to provide point in time metrics for key performance indicators.  MySQL 5.6 improves the Performance Schema in answer to the most common DBA and Developer problems.  New instrumentations include: Statements/Stages What are my most resource intensive queries? Where do they spend time? Table/Index I/O, Table Locks Which application tables/indexes cause the most load or contention? Users/Hosts/Accounts Which application users, hosts, accounts are consuming the most resources? Network I/O What is the network load like? How long do sessions idle? Summaries Aggregated statistics grouped by statement, thread, user, host, account or object. The MySQL 5.6 Performance Schema is now enabled by default in the my.cnf file with optimized and auto-tune settings that minimize overhead (< 5%, but mileage will vary), so using the Performance Schema ona production server to monitor the most common application use cases is less of an issue.  In addition, new atomic levels of instrumentation enable the capture of granular levels of resource consumption by users, hosts, accounts, applications, etc. for billing and chargeback purposes in cloud computing environments.The MySQL docs are an excellent resource for all that is available and that can be done with the 5.6 Performance Schema. Better Condition Handling - GET DIAGNOSTICSMySQL 5.6 enables developers to easily check for error conditions and code for exceptions by introducing the new MySQL Diagnostics Area and corresponding GET DIAGNOSTICS interface command. The Diagnostic Area can be populated via multiple options and provides 2 kinds of information:Statement - which provides affected row count and number of conditions that occurredCondition - which provides error codes and messages for all conditions that were returned by a previous operation The addressable items for each are: The new GET DIAGNOSTICS command provides a standard interface into the Diagnostics Area and can be used via the CLI or from within application code to easily retrieve and handle the results of the most recent statement execution.  An example of how it is used might be:mysql> DROP TABLE test.no_such_table; ERROR 1051 (42S02): Unknown table 'test.no_such_table' mysql> GET DIAGNOSTICS CONDITION 1 -> @p1 = RETURNED_SQLSTATE, @p2 = MESSAGE_TEXT; mysql> SELECT @p1, @p2; +-------+------------------------------------+| @p1   | @p2                                | +-------+------------------------------------+| 42S02 | Unknown table 'test.no_such_table' | +-------+------------------------------------+ Options for leveraging the MySQL Diagnotics Area and GET DIAGNOSTICS are detailed in the MySQL Docs.While the above is a summary of some of the key developer enabling 5.6 features, it is by no means exhaustive. You can dig deeper into what MySQL 5.6 has to offer by reading this developer zone article or checking out "What's New in MySQL 5.6" in the MySQL docs.BONUS ALERT!  If you are developing on Windows or are considering MySQL as an alternative to SQL Server for your next project, application or shipping product, you should check out the MySQL Installer for Windows.  The installer includes the MySQL 5.6 RC database, all drivers, Visual Studio and Excel plugins, tray monitor and development tools all a single download and GUI installer.   So what are your next steps? Register for Dec. 13 "MySQL 5.6: Building the Next Generation of Web-Based Applications and Services" live web event.  Hurry!  Seats are limited. Download the MySQL 5.6 Release Candidate (look under the Development Releases tab) Provide Feedback <link to http://bugs.mysql.com/> Join the Developer discussion on the MySQL Forums Explore all MySQL Products and Developer Tools As always, thanks for your continued support of MySQL!

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• Persistence classes in Qt

  - by zarzych

  Hi, I'm porting a medium-sized CRUD application from .Net to Qt and I'm looking for a pattern for creating persistence classes. In .Net I usually created abstract persistence class with basic methods (insert, update, delete, select) for example: public class DAOBase<T> { public T GetByPrimaryKey(object primaryKey) {...} public void DeleteByPrimaryKey(object primaryKey) {...} public List<T> GetByField(string fieldName, object value) {...} public void Insert(T dto) {...} public void Update(T dto) {...} } Then, I subclassed it for specific tables/DTOs and added attributes for DB table layout: [DBTable("note", "note_id", NpgsqlTypes.NpgsqlDbType.Integer)] [DbField("note_id", NpgsqlTypes.NpgsqlDbType.Integer, "NoteId")] [DbField("client_id", NpgsqlTypes.NpgsqlDbType.Integer, "ClientId")] [DbField("title", NpgsqlTypes.NpgsqlDbType.Text, "Title", "")] [DbField("body", NpgsqlTypes.NpgsqlDbType.Text, "Body", "")] [DbField("date_added", NpgsqlTypes.NpgsqlDbType.Date, "DateAdded")] class NoteDAO : DAOBase<NoteDTO> { } Thanks to .Net reflection system I was able to achieve heavy code reuse and easy creation of new ORMs. The simplest way to do this kind of stuff in Qt seems to be using model classes from QtSql module. Unfortunately, in my case they provide too abstract an interface. I need at least transactions support and control over individual commits which QSqlTableModel doesn't provide. Could you give me some hints about solving this problem using Qt or point me to some reference materials? Update: Based on Harald's clues I've implemented a solution that is quite similar to the .Net classes above. Now I have two classes. UniversalDAO that inherits QObject and deals with QObject DTOs using metatype system: class UniversalDAO : public QObject { Q_OBJECT public: UniversalDAO(QSqlDatabase dataBase, QObject *parent = 0); virtual ~UniversalDAO(); void insert(const QObject &dto); void update(const QObject &dto); void remove(const QObject &dto); void getByPrimaryKey(QObject &dto, const QVariant &key); }; And a generic SpecializedDAO that casts data obtained from UniversalDAO to appropriate type: template<class DTO> class SpecializedDAO { public: SpecializedDAO(UniversalDAO *universalDao) virtual ~SpecializedDAO() {} DTO defaultDto() const { return DTO; } void insert(DTO dto) { dao->insert(dto); } void update(DTO dto) { dao->update(dto); } void remove(DTO dto) { dao->remove(dto); } DTO getByPrimaryKey(const QVariant &key); }; Using the above, I declare the concrete DAO class as following: class ClientDAO : public QObject, public SpecializedDAO<ClientDTO> { Q_OBJECT public: ClientDAO(UniversalDAO *dao, QObject *parent = 0) : QObject(parent), SpecializedDAO<ClientDTO>(dao) {} }; From within ClientDAO I have to set some database information for UniversalDAO. That's where my implementation gets ugly because I do it like this: QMap<QString, QString> fieldMapper; fieldMapper["client_id"] = "clientId"; fieldMapper["name"] = "firstName"; /* ...all column <-> field pairs in here... */ dao->setFieldMapper(fieldMapper); dao->setTable("client"); dao->setPrimaryKey("client_id"); I do it in constructor so it's not visible at a first glance for someone browsing through the header. In .Net version it was easy to spot and understand. Do you have some ideas how I could make it better?

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• Why are there 3 conflicting OpenCV camera calibration formulas?

  - by John

  I'm having a problem with OpenCV's various parameterization of coordinates used for camera calibration purposes. The problem is that three different sources of information on image distortion formulae apparently give three non-equivalent description of the parameters and equations involved: (1) In their book "Learning OpenCV…" Bradski and Kaehler write regarding lens distortion (page 376): xcorrected = x * ( 1 + k1 * r^2 + k2 * r^4 + k3 * r^6 ) + [ 2 * p1 * x * y + p2 * ( r^2 + 2 * x^2 ) ], ycorrected = y * ( 1 + k1 * r^2 + k2 * r^4 + k3 * r^6 ) + [ p1 * ( r^2 + 2 * y^2 ) + 2 * p2 * x * y ], where r = sqrt( x^2 + y^2 ). Assumably, (x, y) are the coordinates of pixels in the uncorrected captured image corresponding to world-point objects with coordinates (X, Y, Z), camera-frame referenced, for which xcorrected = fx * ( X / Z ) + cx and ycorrected = fy * ( Y / Z ) + cy, where fx, fy, cx, and cy, are the camera's intrinsic parameters. So, having (x, y) from a captured image, we can obtain the desired coordinates ( xcorrected, ycorrected ) to produced an undistorted image of the captured world scene by applying the above first two correction expressions. However... (2) The complication arises as we look at OpenCV 2.0 C Reference entry under the Camera Calibration and 3D Reconstruction section. For ease of comparison we start with all world-point (X, Y, Z) coordinates being expressed with respect to the camera's reference frame, just as in #1. Consequently, the transformation matrix [ R | t ] is of no concern. In the C reference, it is expressed that: x' = X / Z, y' = Y / Z, x'' = x' * ( 1 + k1 * r'^2 + k2 * r'^4 + k3 * r'^6 ) + [ 2 * p1 * x' * y' + p2 * ( r'^2 + 2 * x'^2 ) ], y'' = y' * ( 1 + k1 * r'^2 + k2 * r'^4 + k3 * r'^6 ) + [ p1 * ( r'^2 + 2 * y'^2 ) + 2 * p2 * x' * y' ], where r' = sqrt( x'^2 + y'^2 ), and finally that u = fx * x'' + cx, v = fy * y'' + cy. As one can see these expressions are not equivalent to those presented in #1, with the result that the two sets of corrected coordinates ( xcorrected, ycorrected ) and ( u, v ) are not the same. Why the contradiction? It seems to me the first set makes more sense as I can attach physical meaning to each and every x and y in there, while I find no physical meaning in x' = X / Z and y' = Y / Z when the camera focal length is not exactly 1. Furthermore, one cannot compute x' and y' for we don't know (X, Y, Z). (3) Unfortunately, things get even murkier when we refer to the writings in Intel's Open Source Computer Vision Library Reference Manual's section Lens Distortion (page 6-4), which states in part: "Let ( u, v ) be true pixel image coordinates, that is, coordinates with ideal projection, and ( u ~, v ~ ) be corresponding real observed (distorted) image coordinates. Similarly, ( x, y ) are ideal (distortion-free) and ( x ~, y ~ ) are real (distorted) image physical coordinates. Taking into account two expansion terms gives the following: x ~ = x * ( 1 + k1 * r^2 + k2 * r^4 ) + [ 2 p1 * x * y + p2 * ( r^2 + 2 * x^2 ) ] y ~ = y * ( 1 + k1 * r^2 + k2 * r^4 ] + [ 2 p2 * x * y + p2 * ( r^2 + 2 * y^2 ) ], where r = sqrt( x^2 + y^2 ). ... "Because u ~ = cx + fx * u and v ~ = cy + fy * v , … the resultant system can be rewritten as follows: u ~ = u + ( u – cx ) * [ k1 * r^2 + k2 * r^4 + 2 * p1 * y + p2 * ( r^2 / x + 2 * x ) ] v ~ = v + ( v – cy ) * [ k1 * r^2 + k2 * r^4 + 2 * p2 * x + p1 * ( r^2 / y + 2 * y ) ] The latter relations are used to undistort images from the camera." Well, it would appear that the expressions involving x ~ and y ~ coincided with the two expressions given at the top of this writing involving xcorrected and ycorrected. However, x ~ and y ~ do not refer to corrected coordinates, according to the given description. I don't understand the distinction between the meaning of the coordinates ( x ~, y ~ ) and ( u ~, v ~ ), or for that matter, between the pairs ( x, y ) and ( u, v ). From their descriptions it appears their only distinction is that ( x ~, y ~ ) and ( x, y ) refer to 'physical' coordinates while ( u ~, v ~ ) and ( u, v ) do not. What is this distinction all about? Aren't they all physical coordinates? I'm lost! Thanks for any input!

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• DSP - Problems using the inverse Fast Fourier Transform

  - by Trap

  I've been playing around a little with the Exocortex implementation of the FFT, but I'm having some problems. First, after calculating the inverse FFT of an unchanged frequency spectrum obtained by a previous forward FFT, one would expect to get the original signal back, but this is not the case. I had to figure out that I needed to scale the FFT output to about 1 / fftLength to get the amplitudes ok. Why is this? Second, whenever I modify the amplitudes of the frequency bins before calling the iFFT the signal gets distorted at low frequencies. However, this does not happen if I attenuate all the bins by the same factor. Let me put a very simplified example of the output buffer of a 4-sample FFT: // Bin 0 (DC) FFTOut[0] = 0.0000610351563 FFTOut[1] = 0.0 // Bin 1 FFTOut[2] = 0.000331878662 FFTOut[3] = 0.000629425049 // Central bin FFTOut[4] = -0.0000381469727 FFTOut[5] = 0.0 // Bin 3, this is a negative frequency bin. FFTOut[6] = 0.000331878662 FFTOut[7] = -0.000629425049 The output is composed of pairs of floats, each representing the real and imaginay parts of a single bin. So, bin 0 (array indexes 0, 1) would represent the real and imaginary parts of the DC frequency. As you can see, bins 1 and 3 both have the same values, (except for the sign of the Im part), so I guess these are the negative frequency values, and finally indexes (4, 5) would be the central frequency bin. To attenuate the frequency bin 1 this is what I do: // Attenuate the 'positive' bin FFTOut[2] *= 0.5; FFTOut[3] *= 0.5; // Attenuate its corresponding negative bin. FFTOut[6] *= 0.5; FFTOut[7] *= 0.5; For the actual tests I'm using a 1024-length FFT and I always provide all the samples so no 0-padding is needed. // Attenuate var halfSize = fftWindowLength / 2; float leftFreq = 0f; float rightFreq = 22050f; for( var c = 1; c < halfSize; c++ ) { var freq = c * (44100d / halfSize); // Calc. positive and negative frequency locations. var k = c * 2; var nk = (fftWindowLength - c) * 2; // This kind of attenuation corresponds to a high-pass filter. // The attenuation at the transition band is linearly applied, could // this be the cause of the distortion of low frequencies? var attn = (freq < leftFreq) ? 0 : (freq < rightFreq) ? ((freq - leftFreq) / (rightFreq - leftFreq)) : 1; mFFTOut[ k ] *= (float)attn; mFFTOut[ k + 1 ] *= (float)attn; mFFTOut[ nk ] *= (float)attn; mFFTOut[ nk + 1 ] *= (float)attn; } Obviously I'm doing something wrong but can't figure out what or where.

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• How can I implement the Gale-Shapley stable marriage algorithm in Perl?

  - by srk

  Problem : We have equal number of men and women.each men has a preference score toward each woman. So do the woman for each man. each of the men and women have certain interests. Based on the interest we calculate the preference scores. So initially we have an input in a file having x columns. First column is the person(men/woman) id. id are nothing but 0.. n numbers.(first half are men and next half woman) the remaining x-1 columns will have the interests. these are integers too. now using this n by x-1 matrix... we have come up with a n by n/2 matrix. the new matrix has all men and woman as their rows and scores for opposite sex in columns. We have to sort the scores in descending order, also we need to know the id of person related to the scores after sorting. So here i wanted to use hash table. once we get the scores we need to make up pairs.. for which we need to follow some rules. My trouble is with the second matrix of n by n/2 that needs to give information of which man/woman has how much preference on a woman/man. I need these scores sorted so that i know who is the first preferred woman/man, 2nd preferred and so on for a man/woman. I hope to get good suggestions on the data structures i use.. I prefer php or perl. Thank you in advance Hey guys this is not an home work. This a little modified version of stable marriage algorithm. I have working solution. I am only working on optimizing my code. more info: It is very similar to stable marriage problem but here we need to calculate the scores based on the interests they share. So i have implemented it as the way you see in the wiki page http://en.wikipedia.org/wiki/Stable_marriage_problem. my problem is not solving the problem. i solved it and can run it. I am just trying to have a better solution. so i am asking suggestions on the type of data structure to use. Conceptually I tried using an array of hashes. where the array index give the person id and the hash in it gives the id's <= score's in sorted manner. I initially start with an array of hashes. now i sort the hashes on values, but i could not store the sorted hashes back in an array.So just stored the keys after sorting and used these to get the values from my initial unsorted hashes. Can we store the hashes after sorting ? Can you suggest a better structure ?

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• is it right to call ejb bean from thread by ThreadPoolExecutor?

  - by kislo_metal

  I trying to call some ejb bean method from tread. and getting error : (as is glassfish v3) Log Level SEVERE Logger javax.enterprise.system.std.com.sun.enterprise.v3.services.impl Name-Value Pairs {_ThreadName=Thread-1, _ThreadID=42} Record Number 928 Message ID java.lang.NullPointerException at ua.co.rufous.server.broker.TempLicService.run(TempLicService.java Complete Message 35) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:637) here is tread public class TempLicService implements Runnable { String hash; //it`s Stateful bean @EJB private LicActivatorLocal lActivator; public TempLicService(String hash) { this.hash= hash; } @Override public void run() { lActivator.proccessActivation(hash); } } my ThreadPoolExecutor public class RequestThreadPoolExecutor extends ThreadPoolExecutor { private boolean isPaused; private ReentrantLock pauseLock = new ReentrantLock(); private Condition unpaused = pauseLock.newCondition(); private static RequestThreadPoolExecutor threadPool; private RequestThreadPoolExecutor() { super(1, Integer.MAX_VALUE, 10, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); System.out.println("RequestThreadPoolExecutor created"); } public static RequestThreadPoolExecutor getInstance() { if (threadPool == null) threadPool = new RequestThreadPoolExecutor(); return threadPool; } public void runService(Runnable task) { threadPool.execute(task); } protected void beforeExecute(Thread t, Runnable r) { super.beforeExecute(t, r); pauseLock.lock(); try { while (isPaused) unpaused.await(); } catch (InterruptedException ie) { t.interrupt(); } finally { pauseLock.unlock(); } } public void pause() { pauseLock.lock(); try { isPaused = true; } finally { pauseLock.unlock(); } } public void resume() { pauseLock.lock(); try { isPaused = false; unpaused.signalAll(); } finally { pauseLock.unlock(); } } public void shutDown() { threadPool.shutdown(); } //<<<<<< creating thread here public void runByHash(String hash) { Runnable service = new TempLicService(hash); threadPool.runService(service); } } and method where i call it (it is gwt servlet, but there is no proble to call thread that not contain ejb) : @Override public Boolean submitHash(String hash) { System.out.println("submiting hash"); try { if (tBoxService.getTempLicStatus(hash) == 1) { //<<< here is the call RequestThreadPoolExecutor.getInstance().runByHash(hash); return true; } } catch (NoResultException e) { e.printStackTrace(); } return false; } I need to organize some pool of submitting hash to server (calls of LicActivator bean), is ThreadPoolExecutor design good idea and why it is not working in my case? (as I know we can`t create thread inside bean, but could we call bean from different threads? ). If No, what is the bast practice for organize such request pool? Thanks. << Answer: I am using DI (EJB 3.1) soo i do not need any look up here. (application packed in ear and both modules in it (web module and ejb), it works perfect for me). But I can use it only in managed classes. So.. 2.Can I use manual look up in Tread ? Could I use Bean that extends ThreadPoolExecutor and calling another bean that implements Runnable ? Or it is not allowed ?

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• DSP - Filtering in the frequency domain via FFT

  - by Trap

  I've been playing around a little with the Exocortex implementation of the FFT, but I'm having some problems. Whenever I modify the amplitudes of the frequency bins before calling the iFFT the resulting signal contains some clicks and pops, especially when low frequencies are present in the signal (like drums or basses). However, this does not happen if I attenuate all the bins by the same factor. Let me put an example of the output buffer of a 4-sample FFT: // Bin 0 (DC) FFTOut[0] = 0.0000610351563 FFTOut[1] = 0.0 // Bin 1 FFTOut[2] = 0.000331878662 FFTOut[3] = 0.000629425049 // Bin 2 FFTOut[4] = -0.0000381469727 FFTOut[5] = 0.0 // Bin 3, this is the first and only negative frequency bin. FFTOut[6] = 0.000331878662 FFTOut[7] = -0.000629425049 The output is composed of pairs of floats, each representing the real and imaginay parts of a single bin. So, bin 0 (array indexes 0, 1) would represent the real and imaginary parts of the DC frequency. As you can see, bins 1 and 3 both have the same values, (except for the sign of the Im part), so I guess bin 3 is the first negative frequency, and finally indexes (4, 5) would be the last positive frequency bin. Then to attenuate the frequency bin 1 this is what I do: // Attenuate the 'positive' bin FFTOut[2] *= 0.5; FFTOut[3] *= 0.5; // Attenuate its corresponding negative bin. FFTOut[6] *= 0.5; FFTOut[7] *= 0.5; For the actual tests I'm using a 1024-length FFT and I always provide all the samples so no 0-padding is needed. // Attenuate var halfSize = fftWindowLength / 2; float leftFreq = 0f; float rightFreq = 22050f; for( var c = 1; c < halfSize; c++ ) { var freq = c * (44100d / halfSize); // Calc. positive and negative frequency indexes. var k = c * 2; var nk = (fftWindowLength - c) * 2; // This kind of attenuation corresponds to a high-pass filter. // The attenuation at the transition band is linearly applied, could // this be the cause of the distortion of low frequencies? var attn = (freq < leftFreq) ? 0 : (freq < rightFreq) ? ((freq - leftFreq) / (rightFreq - leftFreq)) : 1; // Attenuate positive and negative bins. mFFTOut[ k ] *= (float)attn; mFFTOut[ k + 1 ] *= (float)attn; mFFTOut[ nk ] *= (float)attn; mFFTOut[ nk + 1 ] *= (float)attn; } Obviously I'm doing something wrong but can't figure out what. I don't want to use the FFT output as a means to generate a set of FIR coefficients since I'm trying to implement a very basic dynamic equalizer. What's the correct way to filter in the frequency domain? what I'm missing? Thanks in advance.

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• What are good CLI tools for JSON?

  - by jasonmp85

  General Problem Though I may be diagnosing the root cause of an event, determining how many users it affected, or distilling timing logs in order to assess the performance and throughput impact of a recent code change, my tools stay the same: grep, awk, sed, tr, uniq, sort, zcat, tail, head, join, and split. To glue them all together, Unix gives us pipes, and for fancier filtering we have xargs. If these fail me, there's always perl -e. These tools are perfect for processing CSV files, tab-delimited files, log files with a predictable line format, or files with comma-separated key-value pairs. In other words, files where each line has next to no context. XML Analogues I recently needed to trawl through Gigabytes of XML to build a histogram of usage by user. This was easy enough with the tools I had, but for more complicated queries the normal approaches break down. Say I have files with items like this: <foo user="me"> <baz key="zoidberg" value="squid" /> <baz key="leela" value="cyclops" /> <baz key="fry" value="rube" /> </foo> And let's say I want to produce a mapping from user to average number of <baz>s per <foo>. Processing line-by-line is no longer an option: I need to know which user's <foo> I'm currently inspecting so I know whose average to update. Any sort of Unix one liner that accomplishes this task is likely to be inscrutable. Fortunately in XML-land, we have wonderful technologies like XPath, XQuery, and XSLT to help us. Previously, I had gotten accustomed to using the wonderful XML::XPath Perl module to accomplish queries like the one above, but after finding a TextMate Plugin that could run an XPath expression against my current window, I stopped writing one-off Perl scripts to query XML. And I just found out about XMLStarlet which is installing as I type this and which I look forward to using in the future. JSON Solutions? So this leads me to my question: are there any tools like this for JSON? It's only a matter of time before some investigation task requires me to do similar queries on JSON files, and without tools like XPath and XSLT, such a task will be a lot harder. If I had a bunch of JSON that looked like this: { "firstName": "Bender", "lastName": "Robot", "age": 200, "address": { "streetAddress": "123", "city": "New York", "state": "NY", "postalCode": "1729" }, "phoneNumber": [ { "type": "home", "number": "666 555-1234" }, { "type": "fax", "number": "666 555-4567" } ] } And wanted to find the average number of phone numbers each person had, I could do something like this with XPath: fn:avg(/fn:count(phoneNumber)) Questions Are there any command-line tools that can "query" JSON files in this way? If you have to process a bunch of JSON files on a Unix command line, what tools do you use? Heck, is there even work being done to make a query language like this for JSON? If you do use tools like this in your day-to-day work, what do you like/dislike about them? Are there any gotchas? I'm noticing more and more data serialization is being done using JSON, so processing tools like this will be crucial when analyzing large data dumps in the future. Language libraries for JSON are very strong and it's easy enough to write scripts to do this sort of processing, but to really let people play around with the data shell tools are needed. Related Questions Grep and Sed Equivalent for XML Command Line Processing Is there a query language for JSON? JSONPath or other XPath like utility for JSON/Javascript; or Jquery JSON

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• Change form field options dynamically (and restore previously selected options) using jQuery

  - by Martin

  I'm fairly new to both jQuery and JavaScript so can anyone please point out what I'm missing here? I have a form with multiple pairs of select fields, where the content of the second field relies on the selection of the first one. Once a value is chosen from the first one then a piece of jQuery code empties the corresponding second select options, gets new values as JSON and inserts them as new select values. All of this works with the code I've written. However if a user has chosen a second value, I'd like to restore it if possible (meaning if the new values also include the one previously selected). I tried to do this by first saving the second value and then trying to set it once the new options have been inserted. This did not work. However when trying to debug I inserted an alert() just before restoring the second value and with that in there it does work... Am I missing something very basic here? Any help would be appreciated. HTML: <select name="party-0-first" id="id_party-0-first"> <option value="" selected="selected">---------</option> <option value="1">first_value1</option> <option value="2">first_value2</option> <option value="3">first_value3</option> <option value="4">first_value4</option> </select> <select name="party-0-second" id="id_party-0-second"> <option value="" selected="selected">---------</option> <option value="1">second_value1</option> <option value="2">second_value2</option> <option value="3">second_value3</option> <option value="4">second_value4</option> </select> <select name="party-1-first" id="id_party-1-first"> ... JavaScript: $.fn.setSecond = function() { var divName = $(this).attr("name"); divName = divName.replace('-first', ''); divName = divName.replace('party-', ''); // Save the currently selected value of the "second" select box // This seems to work properly setValue = $('#id_party-' + divName + '-second').val(); // Get the new values $.getJSON("/json_opsys/", { client: $(this).val() }, function(data){ $('#id_party-' + divName + '-second').empty(); $('#id_party-' + divName + '-second').append('<option value="" selected="selected">---------</option>'); $.each(data, function(i, item){ $('#id_party-' + divName + '-second').append('<option value="' + item.pk + '">' + item.fields.name + '</option>'); }); }); // Here I try to restore the selected value // This does not work normally, however if I place a javascript alert() before // this for some reason it does work $('#id_party-' + divName + '-second').val(setValue); $(document).ready(function(){ $('[id*=first]').change(function() { $(this).setSecond(); }); });

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• clojure.algo.monad strange m-plus behaviour with parser-m - why is second m-plus evaluated?

  - by Mark Fisher

  I'm getting unexpected behaviour in some monads I'm writing. I've created a parser-m monad with (def parser-m (state-t maybe-m)) which is pretty much the example given everywhere (here, here and here) I'm using m-plus to act a kind of fall-through query mechanism, in my case, it first reads values from a cache (database), if that returns nil, the next method is to read from "live" (a REST call). However, the second value in the m-plus list is always called, even though its value is disgarded (if the cache hit was good) and the final return is that of the first monadic function. Here's a cutdown version of the issue i'm seeing, and some solutions I found, but I don't know why. My questions are: Is this expected behaviour or a bug in m-plus? i.e. will the 2nd method in a m-plus list always be evaluated if the first item returns a value? Minor in comparison to the above, but if i remove the call _ (fetch-state) from checker, when i evaluate that method, it prints out the messages for the functions the m-plus is calling (when i don't think it should). Is this also a bug? Here's a cut-down version of the code in question highlighting the problem. It simply checks key/value pairs passed in are same as the initial state values, and updates the state to mark what it actually ran. (ns monods.monad-test (:require [clojure.algo.monads :refer :all])) (def parser-m (state-t maybe-m)) (defn check-k-v [k v] (println "calling with k,v:" k v) (domonad parser-m [kv (fetch-val k) _ (do (println "k v kv (= kv v)" k v kv (= kv v)) (m-result 0)) :when (= kv v) _ (do (println "passed") (m-result 0)) _ (update-val :ran #(conj % (str "[" k " = " v "]"))) ] [k v])) (defn filler [] (println "filler called") (domonad parser-m [_ (fetch-state) _ (do (println "filling") (m-result 0)) :when nil] nil)) (def checker (domonad parser-m [_ (fetch-state) result (m-plus ;; (filler) ;; intitially commented out deliberately (check-k-v :a 1) (check-k-v :b 2) (check-k-v :c 3))] result)) (checker {:a 1 :b 2 :c 3 :ran []}) When I run this as is, the output is: > (checker {:a 1 :b 2 :c 3 :ran []}) calling with k,v: :a 1 calling with k,v: :b 2 calling with k,v: :c 3 k v kv (= kv v) :a 1 1 true passed k v kv (= kv v) :b 2 2 true passed [[:a 1] {:a 1, :b 2, :c 3, :ran ["[:a = 1]"]}] I don't expect the line k v kv (= kv v) :b 2 2 true to show at all. The first function to m-plus (as seen in the final output) is what is returned from it. Now, I've found if I pass a filler into m-plus that does nothing (i.e. uncomment the (filler) line) then the output is correct, the :b value isn't evaluated. If I don't have the filler method, and make the first method test fail (i.e. change it to (check-k-v :a 2) then again everything is good, I don't get a call to check :c, only a and b are tested. From my understanding of what the state-t maybe-m transformation is giving me, then the m-plus function should look like: (defn m-plus [left right] (fn [state] (if-let [result (left state)] result (right state)))) which would mean that right isn't called unless left returns nil/false. I'd be interested to know if my understanding is correct or not, and why I have to put the filler method in to stop the extra evaluation (whose effects I don't want to happen). Apologies for the long winded post!

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• ASP.NET MVC 3 embrace dynamic type - CSDN.NET - CSDN Software Development Channel

  - by user559071

  About a decade ago, Microsoft will all bet on the WebForms and static types. With the complete package from scattered to the continuous development, and now almost every page can be viewed as its own procedure. Subsequent years, the industry continued to move in another direction, love is better than separation package, better than the late binding early binding to the idea. This leads to two very interesting questions. The first is the problem of terminology. Consider the original Smalltalk MVC model, view and controller is not only tightly coupled together, and usually in pairs. Most of the framework is that Microsoft, including the classic VB, WinForms, WebForms, WPF and Silverlight, they both use the code behind file to store the controller logic. But said "MVC" usually refers to the view and controller are loosely coupled framework. This is especially true for the Web framework, HTML form submission mechanism allows any views submitted to any of the controller. Since this article was mainly talking about Web technologies, so we need to use the modern definition. The second question is "If you're Microsoft, how to change orbit without causing too much pressure to the developer?" So far, the answer is: new releases each year, until the developers meet up. ASP.NET MVC's first product was released last March. Released in March this year, ASP.NET MVC 2.0. 3.0 RC 2 is currently in phase, expected to be released next March. December 10, Microsoft released ASP.NET MVC 3.0 Release Candidate 2. RC 2 is built on top of Microsoft's commitment to the jQuery: The default project template into jQuery 1.4.4, jQuery Validation 1.7 and jQuery UI. Although people think that Microsoft will focus shifted away from server-side controls to be a joke, but the introduction of Microsoft's jQuery UI is that this is the real thing. For those worried about the scalability of the developers, there are many excellent control can replace the session state. With SessionState property, you can tell the controller session state is read-only, read-write, or can be completely ignored in the. This site is no single server, but if a server needs to access another server session state, then this approach can provide a great help. MVC 3 contains Razor view engine. By default, the engine will be encoded HTML output, so that we can easily output on the screen the text of the original. HTML injection attacks even without the risk of encoded text can not easily prevent the page rendering. For many C # developers in the end do what is most shocking that MVC 3 for the controller and view and embrace the dynamic type. ViewBag property will open a dynamic object, developers can run on top of the object to add attributes. In general, it is used to send the view from the controller non-mode data. Scott Guthrie provides state of the sample contains text (such as the current time) and used to assemble the list box entries. Asked Link: http://www.infoq.com/cn/news/2010/12/ASPNET-MVC-3-RC-2; jsessionid = 3561C3B7957F1FB97848950809AD9483

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