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• ASP.NET Applications Requests/Sec suddenly jumps to a value of about 70 million/sec. on 8 core web

  - by Subhrajit Roy

  We are doing performance testing of an ASP.NET web application with VSTS 2008. We start with 2000 users and slowly ramp up to 5000 users (reaches this user load at around 2.5 hours after the tests start, after this we stay at this user load). The total test duration is of about 6 hours During these runs we have found that the counter Requests/Sec (under category ASP.NET applications) suddenly spikes to a values of 36-72 millions !!!. This keeps on happening intermittently i.e we see this issue once in every 3 performance runs that we give on the same application. In our testing environment we have 4 web servers and interestingly enough we have found that this issue occurs only in the 8 core web servers. Summarizing ... Issue : The counter Requests/Sec (under category ASP.NET Applications) suddenly jumps to a value of about 70 million/sec. on 8 core web servers. This results in an increase in SQL server connections opened by the application. Response time goes for a toss. Error rates also show similar behaviour. However the counter ISAPI Extention Requests/sec does not show any abnormal increase. The graph of this counter almost overlaps with that of counter Requests/Sec till the time of the appearance of the spike.When the spike appears , this counter (ISAPI Extention Requests/sec) actually shows a drop. Test Settings : Performance test run with Visual Studio Team System 2008. Soak test run for 6 hours. Maximum user load 5000 users. This is load is attained at about 2.5 hours into the run and mainted for remaining duration.(i.e for around 3.5 more hrs) This issue is reproducible though happens intermittently. (i.e occurs one in three or four runs) Test Environment : Web site deployed on 4 Web Servers (Windows Server 2003). Of these 2 are 4 core machines and the remaining 2 are 8 core ones. .NET Framework 3.5 SP1 installed on all 4 web servers. Application hosted on IIS 6.0 run in Worker process isolation mode.

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• Heuristic to identify if a series of 4 bytes chunks of data are integers or floats

  - by flint

  What's the best heuristic I can use to identify whether a chunk of X 4-bytes are integers or floats? A human can do this easily, but I wanted to do it programmatically. I realize that since every combination of bits will result in a valid integer and (almost?) all of them will also result in a valid float, there is no way to know for sure. But I still would like to identify the most likely candidate (which will virtually always be correct; or at least, a human can do it). For example, let's take a series of 4-bytes raw data and print them as integers first and then as floats: 1 1.4013e-45 10 1.4013e-44 44 6.16571e-44 5000 7.00649e-42 1024 1.43493e-42 0 0 0 0 -5 -nan 11 1.54143e-44 Obviously they will be integers. Now, another example: 1065353216 1 1084227584 5 1085276160 5.5 1068149391 1.33333 1083179008 4.5 1120403456 100 0 0 -1110651699 -0.1 1195593728 50000 These will obviously be floats. PS: I'm using C++ but you can answer in any language, pseudo code or just in english.

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• Difference in performance between Stax and DOM parsing

  - by Fazal

  I have been using DOM for a long time and as such DOM parsing performance wise has been pretty good. Even when dealing with XML of about 4-7 MB the parsing has been fast. The issue we face with DOM is the memory footprint which become huge as soon as we start dealing with large XMLs. Lately I tried moving to Stax (Streaming parsers for XML) which are supposed top be second generation parsers (reading about Stax it said its the fastest parser now). When I tried stax parser for large XML for about 4MB memory footprint definitely reduced drastically but time take to parse entire XML and create java object out of it increased almost by 5 times over DOM. I used sjsxp.jar implementation of Stax. I can deuce to some extent logically that performance may not be extremely good due to streaming nature of the parser but a reduction of 5 time (e.g. DOM takes about 8 seconds to build object for this XML, whereas Stax parsing took about 40 seconds on average) is definitely not going to be acceptable. Am I missing some point here completely as I am not able to come to terms with these performance numbers

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• Perl, module export symbol

  - by Mike

  I'm having trouble understanding how to export a package symbol to a namespace. I've followed the documentation almost identically, but it seems to not know about any of the exporting symbols. mod.pm #!/usr/bin/perl package mod; use strict; use warnings; require Exporter; @ISA = qw(Exporter); @EXPORT=qw($a); our $a=(1); 1; test.pl $ cat test.pl #!/usr/bin/perl use mod; print($a); This is the result of running it $ ./test.pl Global symbol "@ISA" requires explicit package name at mod.pm line 10. Global symbol "@EXPORT" requires explicit package name at mod.pm line 11. Compilation failed in require at ./test.pl line 3. BEGIN failed--compilation aborted at ./test.pl line 3. $ perl -version This is perl, v5.8.4 built for sun4-solaris-64int

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• Strange behavior due to wx.Frame.SetTitle

  - by Anurag Uniyal

  In a wxPython application, which i am porting to Mac OSX, I set title of app frame every 500msec in update UI event, and due to that all the panels and windows are refreshed. That seems strange to me and almost halts my application which has many custom drawn controls and screens. I wanted to know what could be the reason behind it, is it normal for MAC? Here is a self-constrained script which replicates the scenario using timers. It keeps on printing "on paint" every 500ms because in timer I set title every 500ms. import wx app = wx.PySimpleApp() frame = wx.Frame(None, title="BasePainter Test") painter = wx.Panel(frame) def onPaint(event): dc = wx.PaintDC(painter) print "onPaint" painter.Bind(wx.EVT_PAINT, onPaint) def loop(): frame.SetTitle(frame.GetTitle()) wx.CallLater(500, loop) loop() frame.Show(True) app.SetTopWindow(frame) app.MainLoop() My system details: >>> sys.version '2.5 (r25:51918, Sep 19 2006, 08:49:13) \n[GCC 4.0.1 (Apple Computer, Inc. build 5341)]' >>> wx.VERSION (2, 8, 10, 1, '') >>> os.uname() ('Darwin', 'agyeys-mac-mini.local', '9.8.0', 'Darwin Kernel Version 9.8.0: Wed Jul 15 16:55:01 PDT 2009; root:xnu-1228.15.4~1/RELEASE_I386', 'i386')

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• javascript class calling XMLHttpRequest internally, then handling onreadystatechange

  - by Radu M

  this thing almost works: function myClass(url) { this.source = url; this.rq = null; this.someOtherProperty = "hello"; // open connection to the ajax server this.start = function() { if (window.XMLHttpRequest) { this.rq = new XMLHttpRequest(); if (this.rq.overrideMimeType) this.rq.overrideMimeType("text/xml"); } else this.rq = new ActiveXObject("Microsoft.XMLHTTP"); try { this.rq.onreadystatechange = connectionEvent; this.rq.open("GET", this.source, true); this.rq.send(null); this.state = 1; } catch (err) { // some error handler here } } function connectionEvent() { alert("i'm here"); alert("this doesnt work: " + this.someOtherProperty); } } // myClass so it's nothing more than having the XMLHttpRequest object as a member of my class, instead of globally defined, and invoking it in the traditional way. however, inside my connectionEvent callback function, the meaning of "this" is lost, even though the function itself is scoped inside myClass. i also made sure that the object that i instantiate from myClass is kept alive long enough (declared global in the script). in all the examples of using javascript classes that i saw, "this" was still available inside the inner functions. for me, it is not, even if i take my function outside and make it a myClass.prototype.connectionEvent. what am i doing wrong? thank you.

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• PHP Multiple Calls to Server Share Objects?

  - by user1513171

  I’m wondering this about PHP on Apache. Do multiple calls to the server from different users—could be sitting next to each other, in different states, different countries, etc…—share memory? For example, if I create a static variable in a PHP script and set it to 1 by default, then user1 comes in and it changes to 2, and then almost at the exactly same time, user2 comes in, does he see that static variable with a value of 1 or 2? An even better example is this class I have in PHP: class ApplicationRegistry { private static $instance; private static $PDO; private function __construct() { self::$PDO = $db = new \PDO('mysql:unix_socket=/........'); self::$PDO->setAttribute(\PDO::ATTR_ERRMODE, \PDO::ERRMODE_EXCEPTION); } static function instance() { if(!isset(self::$instance)) { self::$instance = new self(); } return self::$instance; } static function getDSN() { if(!isset(self::$PDO)) { self::instance(); return self::$PDO; } return self::$PDO; } } So this is a Singleton that has a static PDO instance. If user1 and user2 are hitting the server at the exact same time are they using different instances of PDO or are they using the same one? This is a confusing concept for me and I'm trying to think of how my application will scale.

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• How to permanently remove xcuserdata under the project.xcworkspace and resolve uncommitted changes

  - by JeffB6688

  I am struggling with a problem with a merge conflict (see Cannot Merge due to conflict with UserInterfaceState.xcuserstate). Based on feedback, I needed to remove the UserInterfaceState.xcuserstate using git rm. After considerable experimentation, I was able to remove the file with "git rm -rf project.xcworkspace/xcuserdata". So while I was on the branch I was working on, it almost immediately came back as a file that needed to be committed. So I did the git rm on the file again and just switched back to the master. Then I performed a git rm on the file again. The operation again removed the file. But I am still stuck. If I try to merge the branch into the master branch, it again says that I have uncommitted changes. So I go to commit the change. But this time, it shows UserInterfaceState.xcuserstate as the file to commit, but the box is unchecked and it can't be checked. So I can't move forward. Is there a way to use 'git rm' to permanently remove xcuserdata under the project.xcworkspace? Help!! Any ideas?

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• Learning about the low level

  - by Anoners

  I'm interested in learning more about the PC from a lower (machine) level. I graduated from a school which taught us concepts using the Java language which abstracted out that level almost completely. As a result I only learned a bit from the one required assembly language course. In order to cram in ASM and quite a few details about architecture, it was hard to get a very deep picture of what is going on there. At work I focus on unix socket programming in C, so i'm much closer to the hardware now, but I feel I should learn a bit more about what streams really are, how memory management and paging works, what goes on when you call "paint()" on a graphics buffer, etc. I missed out on a lot of this and i'm looking for a good resource to get me started. I've heard a lot about the "Pink Book" by Peter Norton (Programmer's Guide to the IBM PC, Programmer's Guide to inside the PC, etc). It seems like this is on the right track, however the original is quite out dated and the newer ones have had conflicting reviews, with many people saying to stay away from it. I'm not sure what the SO crowd thinks about this book or if they have some suggestions for similar books, online resources, etc that may be good primers for this sort of thing. Any suggestions would be appreciated.

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• Sizers... - wxPython

  - by Francisco Aleixo

  Ok, so I'm learning about sizers in wxPython and I was wondering if it was possible to do something like: ============================================== |WINDOW TITLE _ [] X| |============================================| |xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx| |xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx| |xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx| |xxxxxxxxxxxxxxxxxxNOTEBOOKxxxxxxxxxxxxxxxxxx| |xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx| |xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx| |xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx| |________ ___________| |IMAGE | |LoginForm | |________| |___________| ============================================== NOTE:Yeah, I literally got this from http://stackoverflow.com/questions/1892110/wxpython-picking-the-right-sizer-to-use-in-an-application With NOTEBOOK expanded to left and bottom, IMAGE to align to left and bottom and loginform align to right and bottom and I managed to do almost everything but now I have a problem.. The problem is that I can't align Loginform and Image separately (im using Box Sizers), and I would like to. This is the code I'm using that is causing the problem at the moment, any help is appreciated. NOTE:The code might be (HUGELY) sloppy as I'm still learning box sizers. sizer = wx.BoxSizer(wx.VERTICAL) sizer1 = wx.BoxSizer(wx.HORIZONTAL) sizer1.Add(self.nb,1, wx.EXPAND) sizer.Add(sizer1,1, wx.LEFT | wx.RIGHT | wx.EXPAND, 10) sizer.Add((-1, 25)) sizer2 = wx.BoxSizer(wx.VERTICAL) sizer2.Add(self.userLabel, 0) sizer2.Add(self.userText, 0) sizer2.Add(self.pwdLabel, 0) sizer2.Add(self.pwdText, 0) sizer2.Add(self.rem, 0) sizer3 = wx.BoxSizer(wx.HORIZONTAL) sizer3.Add(self.login, 0) sizer3.Add(self.sair,0, wx.LEFT, 5) sizer2.Add(sizer3, 0) sizer4 = wx.BoxSizer(wx.HORIZONTAL) sizer4.Add(image, 1, wx.LEFT | wx.BOTTOM) sizer4.Add(sizer2,0, wx.RIGHT | wx.BOTTOM , 5) sizer.Add(sizer4,0, wx.ALIGN_RIGHT | wx.RIGHT, 10)

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• x-dom-event-stream in Opera 10 Only Working on First Event

  - by Brad

  I have a python script (in the CherryPy framework) that sends Event: and data: text as this Opera blog post describes to a client browser. The javascript that recieves the x-dom-event-stream content is almost identical to what they show in the blog post. However, the browser displays only the first event sent. Anyone know what I'm missing? I tried a few older versions of Opera and found that it works in Opera 9.52 but not in any newer versions. What did they change? Here is the python code: class dumpData(object): def index(self): cherrypy.response.headers['Content-Type'] = "application/x-dom-event-stream" def yieldData(): i = 0 while 1: yield "Event: count\n" yield "data: " yield i yield "\n\n" i = i + 1 time.sleep(3); return yieldData() index._cp_config = {'response.stream': True} index.exposed = True And here is the javascript/html. Making a request to /data/ runs the python function above. <head> <script> onload = function() { document.getElementById("count").addEventListener("cout", cout, false); } function count(e) { document.getElementById("stream").firstChild.nodeValue = e.data; } </script> <event-source id="count" src="/data/"> </head> <body> <div id="stream"></div> </body> Opening the direct /data/ url in Firefox saves the stream to a file. So I know the output is in the correct format and that the stream works at all.

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• How to set focus to a brand new TextBox which was created as a result of a databinding in WPF?

  - by Mike

  Hi everyone, I have a WPF ItemsControl that is bound to an ObservableCollection. The XAML: <ItemsControl Name="mItemsControl"> <ItemsControl.ItemTemplate> <DataTemplate> <TextBox Text="{Binding Mode=OneWay}"></TextBox> </DataTemplate> </ItemsControl.ItemTemplate> </ItemsControl> The codebehind: private ObservableCollection<string> mCollection = new ObservableCollection<string>(); public MainWindow() { InitializeComponent(); this.mCollection.Add("Test1"); this.mCollection.Add("Test2"); this.mItemsControl.ItemsSource = this.mCollection; } private void Button_Click(object sender, RoutedEventArgs e) { this.mCollection.Add("new item!"); } When I click a button, it adds a new string to the databound ObservableCollection which triggers a new TextBox to appear. I want to give this new textbox focus. I've tried this technique from a related StackOverflow question but it always sets focus to the textbox before the newly created one. private void Button_Click(object sender, RoutedEventArgs e) { this.mCollection.Add("new item!"); // MoveFocus takes a TraversalRequest as its argument. TraversalRequest request = new TraversalRequest(FocusNavigationDirection.Previous); // Gets the element with keyboard focus. UIElement elementWithFocus = Keyboard.FocusedElement as UIElement; // Change keyboard focus. if (elementWithFocus != null) { elementWithFocus.MoveFocus(request); } } My need seems simple enough, but it's almost like the new textbox doesn't really exist until a slight delay after something is added to the ObservableCollection. Any ideas of what would work? Thanks! -Mike

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• How can I improve my real-time behavior in multi-threaded app using pthreads and condition variables

  - by WilliamKF

  I have a multi-threaded application that is using pthreads. I have a mutex() lock and condition variables(). There are two threads, one thread is producing data for the second thread, a worker, which is trying to process the produced data in a real time fashion such that one chuck is processed as close to the elapsing of a fixed time period as possible. This works pretty well, however, occasionally when the producer thread releases the condition upon which the worker is waiting, a delay of up to almost a whole second is seen before the worker thread gets control and executes again. I know this because right before the producer releases the condition upon which the worker is waiting, it does a chuck of processing for the worker if it is time to process another chuck, then immediately upon receiving the condition in the worker thread, it also does a chuck of processing if it is time to process another chuck. In this later case, I am seeing that I am late processing the chuck many times. I'd like to eliminate this lost efficiency and do what I can to keep the chucks ticking away as close to possible to the desired frequency. Is there anything I can do to reduce the delay between the release condition from the producer and the detection that that condition is released such that the worker resumes processing? For example, would it help for the producer to call something to force itself to be context switched out? Bottom line is the worker has to wait each time it asks the producer to create work for itself so that the producer can muck with the worker's data structures before telling the worker it is ready to run in parallel again. This period of exclusive access by the producer is meant to be short, but during this period, I am also checking for real-time work to be done by the producer on behalf of the worker while the producer has exclusive access. Somehow my hand off back to running in parallel again results in significant delay occasionally that I would like to avoid. Please suggest how this might be best accomplished.

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• How do I make Views fill the full width of their parent in my Android app?

  - by Omega

  I have the following layout defined for one of my Activities: <?xml version="1.0" encoding="utf-8"?> <TableLayout android:id="@+id/TableLayout01" android:layout_width="fill_parent" android:layout_height="fill_parent" xmlns:android="http://schemas.android.com/apk/res/android"> <TableRow android:id="@+id/TableRow01" android:layout_height="wrap_content" android:layout_width="fill_parent"> <EditText android:text="Resource Name" android:id="@+id/ResourceName" android:lines="1" android:isScrollContainer="false"></EditText> </TableRow> <TableRow android:id="@+id/TableRow02" android:layout_height="wrap_content" android:layout_width="fill_parent"> <Button android:id="@+id/Tile" android:text="Tile"></Button> </TableRow> </TableLayout> The layout renders almost correctly, the only problem is that my text box and my button aren't occupying the full width of their respective rows. I've tried specifying fill_parent for the layout width properties, but to no avail, they still only occupy roughly half of the screen. Documentation overall for Android so far has been great, but there are a few scenarios like this one where I hit an invisible wall! Thanks for all the help!

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• Making Firefox render canvas text the same as CSS text

  - by Dan Forys

  I've been experimenting with the canvas tag and Javascript. I've made a page that takes Tweets from the Twitter public timeline and animates them into view. It works by using a canvas element in the background for the animation. When the animation is complete, it creates a div element with the same text over the top. I do this so that the tweet text is selectable and links are clickable. Now, in Safari, Chrome and even Opera, the canvas text and div text look almost exactly the same. Yet in Firefox, the size of the text is different enough to make it 'jump' at the point it changes into the div. Does anyone know how to make Firefox render the text the same on the canvas element and the div using CSS? Or is this a rendering inconsistency with the engine. I have put the page on my website if you want to see what I mean. Now for the code: The CSS I'm using for rendering the div contains: line-height: 21px; font-weight: 100; font-family: Georgia, "New Century Schoolbook", "Nimbus Roman No9 L", serif; font-size: 20px; For rendering on the canvas I'm using: this.context.font = this.scale + 'px Georgia'; this.context.fillStyle = "white"; this.context.strokeStyle = 'white'; this.context.fillText(this.text, 0, 0); this.context.strokeText(this.text, 0, 0); where this.scale is an animated scale factor that finishes at 20px exactly. So, to recap, I'm using the same font and ending up at the same px size, yet Firefox renders the text differently between Canvas and CSS. (edit) Here's a screenshot example: First line is the text animating in using canvas, second line is the resulting div.

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• WinForms data binding with a Save button?

  - by Mat

  How is data binding in C# WinForms supposed to work when you have a Save button? I don't want the data updated until I press Save! I have two forms (list and detail) backed by a BindingList<T> collection and my custom object from that collection, respectively. I can bind each form to the list or object appropriately. However, any changes made in the detail form are immediately reflected in the list form - I don't want to save the changes and update the details shown in the list until the Save button is pressed. Is data binding designed to support this? Is there a common pattern for doing so? Whichever way I look at it, binding doesn't seem to be able to support this scenario. I've considered the following: Pass a clone of the object to the detail form, but then I have to reconcile the changes on Save - changes may have been made to the copy in the list in the meantime. Implementing IEditableObject and calling EndEdit on save almost works as I can prevent the list being notified of the changes made until Save is pressed, but if something else causes a refresh the list is updated with the interim data. I'm currently left with dispensing with data binding in my detail view, and doing it all manually. Which is rather annoying.

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• WCF - remote service without using IIS - base address?

  - by Mark Pim

  I'm trying to get my head around the addressing of WCF services. We have a client-server setup where the server occasionally (maybe once a day) needs to push data to each client. I want to have a lightweight WCF listener service on each client hosted in an NT service to receive that data. We already have such an NT service setup hosting some local WCF services for other tasks so the overhead of this is minimal. Because of existing legacy code on the server I believe the service needs to be exposed as ASMX and use basicHttpBinding to allow it to connect. Each client is registered on the server by the user (they need to configure them individually) so discovery is not the issue. My question is, how does the addressing work? I imagine the user entering the client's address on the server in the form http://0.0.0.0/MyService or even http://hostname/MyService If so, how do I configure the client service in its App.config? Do I use localhost? If not then what is the reccommended way of exposing the service to the server? Note: I don't want to host in IIS as that adds extra requirements to the hardware required for the client. The clients will be almost certainly located on LANs, not over the public internet

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• jQuery - Not sure which method to use, closest() and parent() don't work.

  - by Nike

  Hello, again. :) God i feel like i'm spamming stackoverflow, this is my 3rd post for today. Sorry, heh. I even posted a question regarding this before, kind of, but i've changed the code a bit since so i thought it was better to post a new question. $('.pmlist ul li h4 .toggle').click(function() { $(this).closest('.meddel').toggle(250); }); That's what i've got now. The reason why the closest() method isn't working is because the div .meddel is just next to the h4 element. And closest() only crawls right up the DOM tree, ignoring other child elements. Right? parent() works almost the same and doesn't work either. And as i only want to toggle the closest .meddel div in the element, i need something that, yeah justs grabs the nearest one, and not all of them. To clear it up a bit, here's the HTML for one list item: <li class="item"> <h4><a class="toggle">ämne</a><small>2010-04-17 kl 12:54 by <u>nike1</u></small></h4> <div class="meddel"> <span> <img style="max-width: 70%; min-height: 70%;" src="profile-images/nike1.jpg" alt="" /> <a href="account.php?usr=47">nike1</a> </span> <p>text</p> </div> </li> I have several items like that, and if i click one toggle link, i just want the nearest .meddel to be toggled, as mentioned before. Thanks. -Nike

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• How to test views in ASP.NET MVC2 (ala RSpec)

  - by Dmitriy Nagirnyak

  Hi, I am really missing heavily the ability to test Views independently of controllers. The way RSpec allows to do it. What I want to do is to perform assertions on the rendered view (where no controller is involved!). In order to do so I should provide required Model, ViewData and maybe some details from HttpContextBase (when will we get rid of HttpContext!). So far I have not found anything that allows doing it. Also it might heavily depend on the ViewEngine being used. List of things that views might contain are: Partial views (may be nested deeply). Master pages (or similar in other view engines). Html helpers generating links and other elements. Generally almost anything in a range of common sense :) . Also please note that I am not talking about client-side testing and thus Selenium is just not related to it at all. It is just plain .NET testing. So are there any options to actually do the testing of views? Thanks, Dmitriy.

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• How Random is System.Guid.NewGuid()? (Take two)

  - by Vilx-

  Before you start marking this as a duplicate, read me out. The other question has a (most likely) incorrect accepted answer. I do not know how .NET generates its GUIDs, probably only Microsoft does, but there's a high chance it simply calls CoCreateGuid(). That function however is documented to be calling UuidCreate(). And the algorithms for creating an UUID are pretty well documented. Long story short, be as it may, it seems that System.Guid.NewGuid() indeed uses version 4 UUID generation algorithm, because all the GUIDs it generates matches the criteria (see for yourself, I tried a couple million GUIDs, they all matched). In other words, these GUIDs are almost random, except for a few known bits. This then again raises the question - how random IS this random? As every good little programmer knows, a pseudo-random number algorithm is only as random as its seed (aka entropy). So what is the seed for UuidCreate()? How ofter is the PRNG re-seeded? Is it cryptographically strong, or can I expect the same GUIDs to start pouring out if two computers accidentally call System.Guid.NewGuid() at the same time? And can the state of the PRNG be guessed if sufficiently many sequentially generated GUIDs are gathered?

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• Sync Vs. Async Sockets Performance in .NET

  - by Michael Covelli

  Everything that I read about sockets in .NET says that the asynchronous pattern gives better performance (especially with the new SocketAsyncEventArgs which saves on the allocation). I think this makes sense if we're talking about a server with many client connections where its not possible to allocate one thread per connection. Then I can see the advantage of using the ThreadPool threads and getting async callbacks on them. But in my app, I'm the client and I just need to listen to one server sending market tick data over one tcp connection. Right now, I create a single thread, set the priority to Highest, and call Socket.Receive() with it. My thread blocks on this call and wakes up once new data arrives. If I were to switch this to an async pattern so that I get a callback when there's new data, I see two issues The threadpool threads will have default priority so it seems they will be strictly worse than my own thread which has Highest priority. I'll still have to send everything through a single thread at some point. Say that I get N callbacks at almost the same time on N different threadpool threads notifying me that there's new data. The N byte arrays that they deliver can't be processed on the threadpool threads because there's no guarantee that they represent N unique market data messages because TCP is stream based. I'll have to lock and put the bytes into an array anyway and signal some other thread that can process what's in the array. So I'm not sure what having N threadpool threads is buying me. Am I thinking about this wrong? Is there a reason to use the Async patter in my specific case of one client connected to one server?

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• WPF - How to properly reference a class from XAML

  - by Andy T

  OK, this is a super super noob question, one that I'm almost embarrassed to ask... I want to reference a class in my XAML file. It's a DataTemplateSelector for selecting the right edit template for a DataGrid column. Anyway, I've written the class into my code behind, added the local namespace to the top of top of the XAML, but when I try to reference the class from the XAML, it tells me the class does not exist in the local namespace. I must be missing something really really simple but I just can't understand it... Here's my code. XAML: <Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:tk="http://schemas.microsoft.com/wpf/2008/toolkit" xmlns:local="clr-namespace:CustomFields" xmlns:col="clr-namespace:System.Collections;assembly=mscorlib" xmlns:sys="clr-namespace:System;assembly=mscorlib" x:Class="CustomFields.MainWindow" x:Name="Window" Title="Define Custom Fields" Width="425" Height="400" MinWidth="425" MinHeight="400"> <Window.Resources> <ResourceDictionary> <local:RangeValuesEditTemplateSelector> blah blah blah... </local:RangeValuesEditTemplateSelector> </ResourceDictionary> </Window.Resources> C#: namespace CustomFields { /// /// Interaction logic for MainWindow.xaml /// public partial class MainWindow : Window { public MainWindow() { this.InitializeComponent(); // Insert code required on object creation below this point. } } public class RangeValuesEditTemplateSelector : DataTemplateSelector { public RangeValuesEditTemplateSelector(){ MessageBox.Show("hello"); } } } Any ideas what I'm doing wrong? I thought this should be simple as 1-2-3... Thanks! AT

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• Checking for Repeated Strings in 2d list

  - by Zach Santiago

  i have a program where i have a list of names and classes. i have the list in alphabetical order. now im trying to check if names repeat, add the classes to one single name. im trying to write some code like go through names if name is already in list, add the class to the one name. so an example would be, instead of having 'Anita ','phys 1443', and 'Anita','IE 3312' i would just have 'Anita','PHYS 1443','IE 3312'. How would i go about doing this in a logival way, WITHOUT using any sort of built in functions? i tried comparing indexe's like if list[i][0] == list[i+1][0], append list[i+1][1] to an emptylist. while that almost worked, it would screw up at some points along the way. here is my attempt size = len(c) i = 0 c = [['Anita', 'PHYS 1443'], ['Anita', 'IE 3312'], ['Beihuang', 'PHYS 1443'], ['Chiao-Lin', 'MATH 1426'], ['Chiao-Lin', 'IE 3312'], ['Christopher', 'CSE 1310'], ['Dylan', 'CSE 1320'], ['Edmund', 'PHYS 1443'], ['Ian', 'IE 3301'], ['Ian', 'CSE 1320'], ['Ian', 'PHYS 1443'], ['Isis', 'PHYS 1443'], ['Jonathan', 'MATH 2325'], ['Krishna', 'MATH 2325'], ['Michael', 'IE 3301'], ['Nang', 'MATH 2325'], ['Ram', 'CSE 1320'], ['Taesu', 'CSE 1320'], ["Tre'Shaun", 'IE 3312'], ["Tre'Shaun", 'MATH 2325'], ["Tre'Shaun", 'CSE 1310']] ## Check if any names repeat d.append(c[0][0]) while i < size - 1 : if c[i][0] == c[i+1][0] : d.append(c[i][1]) d.append(c[i+1][1]) else : d.append(c[i+1][0]) d.append(c[i+1][1]) i = i + 1 print d output was. ['Anita', 'PHYS 1443', 'IE 3312', 'Beihuang', 'PHYS 1443', 'Chiao-Lin', 'MATH 1426', 'MATH 1426', 'IE 3312', 'Christopher', 'CSE 1310', 'Dylan', 'CSE 1320', 'Edmund', 'PHYS 1443', 'Ian', 'IE 3301', 'IE 3301', 'CSE 1320', 'CSE 1320', 'PHYS 1443', 'Isis', 'PHYS 1443', 'Jonathan', 'MATH 2325', 'Krishna', 'MATH 2325', 'Michael', 'IE 3301', 'Nang', 'MATH 2325', 'Ram', 'CSE 1320', 'Taesu', 'CSE 1320', "Tre'Shaun", 'IE 3312', 'IE 3312', 'MATH 2325', 'MATH 2325', 'CSE 1310']

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• Reporting System architecture for better performance

  - by pauloya

  Hi, We have a product that runs Sql Server Express 2005 and uses mainly ASP.NET. The database has around 200 tables, with a few (4 or 5) that can grow from 300 to 5000 rows per day and keep a history of 5 years, so they can grow to have 10 million rows. We have built a reporting platform, that allows customers to build reports based on templates, fields and filters. We face performance problems almost since the beginning, we try to keep reports display under 10 seconds but some of them go up to 25 seconds (specially on those customers with long history). We keep checking indexes and trying to improve the queries but we get the feeling that there's only so much we can do. Off course the fact that the queries are generated dynamically doesn't help with the optimization. We also added a few tables that keep redundant data, but then we have the added problem of maintaining this data up to date, and also Sql Express has a limit on the size of databases. We are now facing a point where we have to decide if we want to give up real time reports, or maybe cut the history to be able to have better performance. I would like to ask what is the recommended approach for this kind of systems. Also, should we start looking for third party tools/platforms? I know OLAP can be an option but can we make it work on Sql Server Express, or at least with a license that is cheap enough to distribute to thousands of deployments? Thanks

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• Does my API design violate RESTful principles?

  - by peta

  Hello everybody, I'm currently (I try to) designing a RESTful API for a social network. But I'm not sure if my current approach does still accord to the RESTful principles. I'd be glad if some brighter heads could give me some tips. Suppose the following URI represents the name field of a user account: people/{UserID}/profile/fields/name But there are almost hundred possible fields. So I want the client to create its own field views or use predefined ones. Let's suppose that the following URI represents a predefined field view that includes the fields "name", "age", "gender": utils/views/field-views/myFieldView And because field views are kind of higher logic I don't want to mix support for field views into the "people/{UserID}/profile/fields" resource. Instead I want to do the following: utils/views/field-views/myFieldView/{UserID} Though Leonard Richardson & Sam Ruby state in their book "RESTful Web Services" that a RESTful design is somehow like an "extreme object oriented" approach, I think that my approach is object oriented and therefore accords to RESTful principles. Or am I wrong? When not: Are such "object oriented" approaches generally encouraged when used with care and in order to avoid query-based REST-RPC hybrids? Thanks for your feedback in advance, peta

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