connor black - Page 90 - Developer IT

Will releasing an iPhone app makes it available for iPad by default?

- by agro1986

In my XCode's Targets summary screen, the "Devices" drop down is set to "iPhone" (other possible values are iPad and Universal) because I haven't fine tuned the app's UI for iPad. However, will people be able to download and run my app from the iPad in non-fullscreen? (e.g., with black border surrounding most of the screen) I want people to be able to search for it in app store, install it, and run it even though it is not full screen. Thanks a lot

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Resize a MovieClip on AS2 in function of text len?

- by DomingoSL

Hello, i have a AS2 script who get information from a MySQL database. This information is a text from 0 to 300 chars. I want to display that text in this layout: I want to resize the black box you see on the picture in function of the amount of text imported. Any idea of how to do that on AS2? The instance name of the box is: cargador.fondo (only want to resize height) The instance name of the text is: cargador.texto Thanks.

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How to load and show an png image in matlab?

- by user198729

>> I = imread('D:\Works\matlab\SecCode.php.png','png'); >> imshow(I); The above always shows an all-black one,what's wrong with it?

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.Net: how can I have a combobox with multitple fields of its data source as Displaymember?

- by odiseh

hi How can I have a combobox with multiple fields of its data source as its display member without adding additional columns to its data source? I mean I wanna to have a combobox with displaymember like "ID" + "-" "Name" . 1 - Black 2 - White 3 - Red I DO NOT want to add additional column to its data source. Thank you

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borders are not visible in ie7

- by S.Rangaraj

i want a border on bottom of a td.i got that using border:dotted 1px black;.but it is not visible in ie7.the td height is 10px.if i use &nbsp it is visible in ie7.but i dont need that much height.can anyone help me?

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Silverlight + How to create a bordered table?

- by user208662

Hello, I am currently using Silverlight 3. I want to create the equivalent of a 2x2 HTML table. I want each cell to have a black border. How do I do this in Silverlight? Isn't there a property I can set on a Grid element to make each cell have a border? Thank you,

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Bypass BIOS password set by faulty Toshiba firmware on Satellite A55 laptop?

- by Brian

How can the CMOS be cleared on the Toshiba Satellite A55-S1065? I have this 7 year old laptop that has been crippled by a glitch in its BIOS: 'A "Password =" prompt may be displayed when the computer is turned on, even though no power-on password has been set. If this happens, there is no password that will satisfy the password request. The computer will be unusable until this problem is resolved. [..] The occurrence of this problem on any particular computer is unpredictable -- it may never happen, but it could happen any time that the computer is turned on. [..] Toshiba will cover the cost of this repair under warranty until Dec 31, 2010.' -Toshiba As they stated, this machine is "unusable." The escape key does not bypass the prompt (nor does any other key), thus no operating system can be booted and no firmware updates can be installed. After doing some research, I found solutions that have been suggested for various Toshiba Satellite models afflicted by this glitch: "Make arrangements with a Toshiba Authorized Service Provider to have this problem resolved." -Toshiba (same link). Even prior to the expiration of Toshiba's support ("repair under warranty until Dec 31, 2010"), there have been reports that this solution is prohibitively expensive, labor charges accruing even when the laptop is still under warranty, and other reports that are generally discouraging: "They were unable to fix it and the guy who worked on it said he couldn’t find the jumpers on the motherboard to clear the BIOS. I paid $39 for my troubles and still have the password problem." - Steve. Since the costs of the repairs can now exceed the value of the hardware, it would seem this is a DIY solution, or a non-solution (i.e. the hardware is trash). Build a Toshiba parallel loopback by stripping and soldering the wires on a DB25 plug to connect connect these pins: 1-5-10, 2-11, 3-17, 4-12, 6-16, 7-13, 8-14, 9-15, 18-25. -CGSecurity. According to a list of supported models on pwcrack, this will likely not work for my Satellite A55-1065 (as well as many other models of similar age). -pwcrack Disconnect the laptop battery for an extended period of time. Doesn't work, laptop sat in a closet for several years without the battery connected and I forgot about the whole thing for awhile. The poor thing. Clear CMOS by setting the proper jumper setting or by removing the CMOS (RTC) battery, or by short circuiting a (hidden?) jumper that looks like a pair of solder marks -various sources for various Satellite models: Satellite A105: "you will see C88 clearly labeled right next the jack that the wireless card plugs into. There are two little solder squares (approx 1/16") at this location" -kerneltrap Satellite 1800: "Underneath the RAM there is black sticker, peel off the black sticker and you will reveal two little solder marks which are actually 'jumpers'. Very carefully hold a flat-head screwdriver touching both points and power on the unit briefly, effectively 'shorting' this circuit." -shadowfax2020 Satellite L300: "Short the B500 solder pads on the system board." -Lester Escobar Satellite A215: "Short the B500 solder pads on the system board." -fixya Clearing the CMOS could resolve the issue, but I cannot locate a jumper or a battery on this board. Nothing that looks remotely like a battery can be removed (everything is soldered). I have looked closely at the area around the memory and do not see any obvious solder pads that could be a secret jumper. Here are pictures (click for full resolution) : Where is the jumper (or solder pads) to short circuit and wipe the CMOS on this board? Possibly related questions: Remove Toshiba laptop BIOS password? Password Problem Toshiba Satellite..

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How to configure emacs by using this file?

- by Andy Leman

From http://public.halogen-dg.com/browser/alex-emacs-settings/.emacs?rev=1346 I got: (setq load-path (cons "/home/alex/.emacs.d/" load-path)) (setq load-path (cons "/home/alex/.emacs.d/configs/" load-path)) (defconst emacs-config-dir "~/.emacs.d/configs/" "") (defun load-cfg-files (filelist) (dolist (file filelist) (load (expand-file-name (concat emacs-config-dir file))) (message "Loaded config file:%s" file) )) (load-cfg-files '("cfg_initsplit" "cfg_variables_and_faces" "cfg_keybindings" "cfg_site_gentoo" "cfg_conf-mode" "cfg_mail-mode" "cfg_region_hooks" "cfg_apache-mode" "cfg_crontab-mode" "cfg_gnuserv" "cfg_subversion" "cfg_css-mode" "cfg_php-mode" "cfg_tramp" "cfg_killbuffer" "cfg_color-theme" "cfg_uniquify" "cfg_tabbar" "cfg_python" "cfg_ack" "cfg_scpaste" "cfg_ido-mode" "cfg_javascript" "cfg_ange_ftp" "cfg_font-lock" "cfg_default_face" "cfg_ecb" "cfg_browser" "cfg_orgmode" ; "cfg_gnus" ; "cfg_cyrillic" )) ; enable disabled advanced features (put 'downcase-region 'disabled nil) (put 'scroll-left 'disabled nil) (put 'upcase-region 'disabled nil) ; narrow cursor ;(setq-default cursor-type 'hbar) (cua-mode) ; highlight current line (global-hl-line-mode 1) ; AV: non-aggressive scrolling (setq scroll-conservatively 100) (setq scroll-preserve-screen-position 't) (setq scroll-margin 0) (custom-set-variables ;; custom-set-variables was added by Custom. ;; If you edit it by hand, you could mess it up, so be careful. ;; Your init file should contain only one such instance. ;; If there is more than one, they won't work right. '(ange-ftp-passive-host-alist (quote (("redbus2.chalkface.com" . "on") ("zope.halogen-dg.com" . "on") ("85.119.217.50" . "on")))) '(blink-cursor-mode nil) '(browse-url-browser-function (quote browse-url-firefox)) '(browse-url-new-window-flag t) '(buffers-menu-max-size 30) '(buffers-menu-show-directories t) '(buffers-menu-show-status nil) '(case-fold-search t) '(column-number-mode t) '(cua-enable-cua-keys nil) '(user-mail-address "[email protected]") '(cua-mode t nil (cua-base)) '(current-language-environment "UTF-8") '(file-name-shadow-mode t) '(fill-column 79) '(grep-command "grep --color=never -nHr -e * | grep -v .svn --color=never") '(grep-use-null-device nil) '(inhibit-startup-screen t) '(initial-frame-alist (quote ((width . 80) (height . 40)))) '(initsplit-customizations-alist (quote (("tabbar" "configs/cfg_tabbar.el" t) ("ecb" "configs/cfg_ecb.el" t) ("ange\\-ftp" "configs/cfg_ange_ftp.el" t) ("planner" "configs/cfg_planner.el" t) ("dired" "configs/cfg_dired.el" t) ("font\\-lock" "configs/cfg_font-lock.el" t) ("speedbar" "configs/cfg_ecb.el" t) ("muse" "configs/cfg_muse.el" t) ("tramp" "configs/cfg_tramp.el" t) ("uniquify" "configs/cfg_uniquify.el" t) ("default" "configs/cfg_font-lock.el" t) ("ido" "configs/cfg_ido-mode.el" t) ("org" "configs/cfg_orgmode.el" t) ("gnus" "configs/cfg_gnus.el" t) ("nnmail" "configs/cfg_gnus.el" t)))) '(ispell-program-name "aspell") '(jabber-account-list (quote (("[email protected]")))) '(jabber-nickname "AVK") '(jabber-password nil) '(jabber-server "halogen-dg.com") '(jabber-username "alex") '(remember-data-file "~/Plans/remember.org") '(safe-local-variable-values (quote ((dtml-top-element . "body")))) '(save-place t nil (saveplace)) '(scroll-bar-mode (quote right)) '(semantic-idle-scheduler-idle-time 432000) '(show-paren-mode t) '(svn-status-hide-unmodified t) '(tool-bar-mode nil nil (tool-bar)) '(transient-mark-mode t) '(truncate-lines f) '(woman-use-own-frame nil)) ; ?? ????? ??????? y ??? n? (fset 'yes-or-no-p 'y-or-n-p) (custom-set-faces ;; custom-set-faces was added by Custom. ;; If you edit it by hand, you could mess it up, so be careful. ;; Your init file should contain only one such instance. ;; If there is more than one, they won't work right. '(compilation-error ((t (:foreground "tomato" :weight bold)))) '(cursor ((t (:background "red1")))) '(custom-variable-tag ((((class color) (background dark)) (:inherit variable-pitch :foreground "DarkOrange" :weight bold)))) '(hl-line ((t (:background "grey24")))) '(isearch ((t (:background "orange" :foreground "black")))) '(message-cited-text ((((class color) (background dark)) (:foreground "SandyBrown")))) '(message-header-name ((((class color) (background dark)) (:foreground "DarkGrey")))) '(message-header-other ((((class color) (background dark)) (:foreground "LightPink2")))) '(message-header-subject ((((class color) (background dark)) (:foreground "yellow2")))) '(message-separator ((((class color) (background dark)) (:foreground "thistle")))) '(region ((t (:background "brown")))) '(tooltip ((((class color)) (:inherit variable-pitch :background "IndianRed1" :foreground "black"))))) The above is a python emacs configure file. Where should I put it to use it? And, are there any other changes I need to make?

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Chrome does not re-draw properly on Windows 8

- by Akshat Mittal

There are a lot of problems with Chrome (24.0.1312.14 beta || But all this happened before update also) on Windows 8. Problems and explanations are listed below: Google Chrome re-draw time: When I switch tabs, the window retains the content of the previous tab and displays that even if I move my mouse, if only refreshes (re-draws) when there is a change on the webpage (like on hover) or I do a select all (or scroll). One thing to note is that the hover and select happens on the real page and not the retained image-like thing of the older webpage. Chrome is slow and laggy: Websites such as Facebook and Twitter (and more) have gone extremely laggy on Chrome (Win 8). When I was using Windows 7, I never experienced a lag or something. Also when using HTML-5 Websites, the transition (the -webkit-transition in CSS) goes extremely slow at times. Plugins Crash: Plugins like Flash Player, Shockwave Player, and more that are in-built into Chrome Crashes a lot, even when doing simple tasks like playing YouTube Videos, displaying ads or something. Chrome Crashes: Chrome has crashed over 100 times in the past month. Google Chrome just crashes randomly or I don't know the reason. Random Page crashes: Chrome results chrome://crash/(Copy-Paste this in address bar) on random pages even when the page is just loaded, I understand that this can happen on heavy HTML5 or JS websites but what about HTML only websites? Computer Freeze: Chrome sometimes, randomly, freezes my computer. Freeze in the sense, none of the other apps are also working. It's like the whole system freezes, I can not even switch to other apps. I am sure that this is because of Chrome since this happens only when Chrome is active. Most of the things above happens on Super User also, Super User never had any problem when using Chrome on Windows 7. UPDATE 1: @magicandre1981 Commented for trying to disable Hardware Acceleration. I tried it, it somewhat solved the problem but din't fix it. I am still experiencing all the above issues but less frequently (maybe because Chrome Restarted Completely) UPDATE 2: @avirk asked me to try a Stable Version of Chrome and Firefox, I din't experience any lag in Firefox, a little (negligible) lag in Chrome 22 (Maybe because its a new copy of Chrome, I haven't used it much). UPDATE 3: @NothingsImpossible said that He is also experiencing the same problem on Windows Server 2008! This seams to be a major issue now. He also said that GPU load is also high at the same time! Even I saw the same thing. UPDATE 4: Recently, Chrome updated to v24 Stable (I am using stable from a long time now). I was experiencing this problem a lot less in Chrome 23, but this is back in Chrome 24. Seams like Chrome 24 is the most affected from this bug, as this same problem was high in Chrome 24 beta also. UPDATE 5: Chrome was updated to v25 Stable. This problem is 99% Gone, it is still there in 1% of the cases. One such example is when I leave chrome inactive for a while with a few tabs open, the tabs go black and no activity can get them back to active state. If I open a new tab, the new tab is OK but the others are still black, I need to close all those tabs. UPDATE 6: Chrome updated to v27 Stable channel, this problem is nearly gone. This does happen occasionally, but not as frequent as in earlier versions of Chrome. UPDATE 7: I am on Chrome v35.0.1916.114 Stable, Windows 8.1 Pro Update 1. Some of the other problems appears to be back. Chrome is slow and laggy again. Re-draw time is getting worse. Is anybody else experiencing such issues? Does anybody have a solution to any of these?

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My computer freezes irregurarly

- by Manhim

My computer started to freeze at irregular times for 3 weeks now. What happens My computer freezes, the video stops. (No graphic glitches, it just stops) Sound keeps playing up to some time (Usually 10-30 seconds) then stops playing. Sometimes, randomly, the screen on my G-15 keyboard flickers and I see caracters not at the right places. Usually happens for about 1-2 seconds and a bit before my computer freezes. I have to keep the power button pressed for 4 seconds to shut my computer down. I still hear my hard drives and fans working. Sometimes it works with no problems for a full day, some other times it just keeps freezing each time I restart my computer and I have to leave it for the rest of the day. Sometimes my mouse freezes for a fraction of a second (Like 0.01 to 0.2 seconds) quite randomly, usually before it freezes. No errors spotted by the "Action center" unlike when I had problems with my last video card on this system (Driver errors). My G-15 LCD screen also freezes. What I did so far I have had similar problems in the past and I had changed my hard drive (It was faulty), so I tested my software RAID-0 array and it was faulty so I changed it. (I reinstalled Windows 7 with this part). I also tested with unplugging my secondary hard drive. My CPU was running at about 100 degree Celsius, I removed the dust between the fans and the heatsink and it's now between 50-60. I ran a CPU stress-test and it didn't freeze during the tests (using Prime95 on all cores) Ran a memory test (using memtest86+) for a single pass and there were no errors. Ran a GPU stress test with ati-tools and furmark and it didn't freeze during the tests. (No artefacts either) I had troubles with my graphic card when I got it, but I think that it got fixed with a driver update. I checked the voltages in my BIOS setup and they all seemed ok (±0.2 I think). I have ran on the computer without problems with Fedora 15 on an external hard drive (Appart that it couldn't load Gnome 3 and was reverting to Gnome 2, didn't want to install drivers since I use it on multiple computers) I used it to backup my files from the raid array to my 1TB hard drive for the reinstallation of Windows. (So the crashes only happenned on Windows) [The external hard drive is plugged directly on a SATA port] I contacted EVGA (My graphic card vendor) and pointed them on this question, I'm looking for an answer. Ran sensors on Fedora 15 and got this output: http://pastebin.com/0BHJnAvu When it happens When I play video games (Mostly) When I play flash games (Second most) When I'm looking at my desktop background (It rarely happens when I have a window open, but it does, sometimes) Specs Windows Seven x64 Home Premium Motherboard: M2N-SLI Deluxe CPU: AMD Phenom 9950 x2 @ 2.6GHz Memory: Kingston 4x2GB Dual Channel (Pretty basic memory sticks) Hard drives: Was 2x250GB (Western digital caviar) in raid-0 + 1TB (WD caviar black), I replaced the raid array with a 750GB (WD caviar black) [Yes I removed the array from the raid configurations] 750W Power supply No overcloking. Ever. There have been some power-downs like 4-5 weeks ago, but the problem didn't start immediately after. (I wasn't home, so my computer got shut-down) My current to-try list Change the thermal paste on my CPU. Change my graphic card with a temporary one and stress the computer. Change my power supply. In this situation, how can I successfully pin-point the current hardware problem? (If it's a hardware problem) Because I don't really have the budget to just forget and replace everything. I also don't really have hardware to test-replace current hardware.

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

- by Reed

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

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Parallelism in .NET – Part 18, Task Continuations with Multiple Tasks

- by Reed

In my introduction to Task continuations I demonstrated how the Task class provides a more expressive alternative to traditional callbacks. Task continuations provide a much cleaner syntax to traditional callbacks, but there are other reasons to switch to using continuations… Task continuations provide a clean syntax, and a very simple, elegant means of synchronizing asynchronous method results with the user interface. In addition, continuations provide a very simple, elegant means of working with collections of tasks. Prior to .NET 4, working with multiple related asynchronous method calls was very tricky. If, for example, we wanted to run two asynchronous operations, followed by a single method call which we wanted to run when the first two methods completed, we’d have to program all of the handling ourselves. We would likely need to take some approach such as using a shared callback which synchronized against a common variable, or using a WaitHandle shared within the callbacks to allow one to wait for the second. Although this could be accomplished easily enough, it requires manually placing this handling into every algorithm which requires this form of blocking. This is error prone, difficult, and can easily lead to subtle bugs. Similar to how the Task class static methods providing a way to block until multiple tasks have completed, TaskFactory contains static methods which allow a continuation to be scheduled upon the completion of multiple tasks: TaskFactory.ContinueWhenAll. This allows you to easily specify a single delegate to run when a collection of tasks has completed. For example, suppose we have a class which fetches data from the network. This can be a long running operation, and potentially fail in certain situations, such as a server being down. As a result, we have three separate servers which we will “query” for our information. Now, suppose we want to grab data from all three servers, and verify that the results are the same from all three. With traditional asynchronous programming in .NET, this would require using three separate callbacks, and managing the synchronization between the various operations ourselves. The Task and TaskFactory classes simplify this for us, allowing us to write: var server1 = Task.Factory.StartNew( () => networkClass.GetResults(firstServer) ); var server2 = Task.Factory.StartNew( () => networkClass.GetResults(secondServer) ); var server3 = Task.Factory.StartNew( () => networkClass.GetResults(thirdServer) ); var result = Task.Factory.ContinueWhenAll( new[] {server1, server2, server3 }, (tasks) => { // Propogate exceptions (see below) Task.WaitAll(tasks); return this.CompareTaskResults( tasks[0].Result, tasks[1].Result, tasks[2].Result); }); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This is clean, simple, and elegant. The one complication is the Task.WaitAll(tasks); statement. Although the continuation will not complete until all three tasks (server1, server2, and server3) have completed, there is a potential snag. If the networkClass.GetResults method fails, and raises an exception, we want to make sure to handle it cleanly. By using Task.WaitAll, any exceptions raised within any of our original tasks will get wrapped into a single AggregateException by the WaitAll method, providing us a simplified means of handling the exceptions. If we wait on the continuation, we can trap this AggregateException, and handle it cleanly. Without this line, it’s possible that an exception could remain uncaught and unhandled by a task, which later might trigger a nasty UnobservedTaskException. This would happen any time two of our original tasks failed. Just as we can schedule a continuation to occur when an entire collection of tasks has completed, we can just as easily setup a continuation to run when any single task within a collection completes. If, for example, we didn’t need to compare the results of all three network locations, but only use one, we could still schedule three tasks. We could then have our completion logic work on the first task which completed, and ignore the others. This is done via TaskFactory.ContinueWhenAny: var server1 = Task.Factory.StartNew( () => networkClass.GetResults(firstServer) ); var server2 = Task.Factory.StartNew( () => networkClass.GetResults(secondServer) ); var server3 = Task.Factory.StartNew( () => networkClass.GetResults(thirdServer) ); var result = Task.Factory.ContinueWhenAny( new[] {server1, server2, server3 }, (firstTask) => { return this.ProcessTaskResult(firstTask.Result); }); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Here, instead of working with all three tasks, we’re just using the first task which finishes. This is very useful, as it allows us to easily work with results of multiple operations, and “throw away” the others. However, you must take care when using ContinueWhenAny to properly handle exceptions. At some point, you should always wait on each task (or use the Task.Result property) in order to propogate any exceptions raised from within the task. Failing to do so can lead to an UnobservedTaskException.

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Microsoft TypeScript : A Typed Superset of JavaScript

- by shiju

JavaScript is gradually becoming a ubiquitous programming language for the web, and the popularity of JavaScript is increasing day by day. Earlier, JavaScript was just a language for browser. But now, we can write JavaScript apps for browser, server and mobile. With the advent of Node.js, you can build scalable, high performance apps on the server with JavaScript. But many developers, especially developers who are working with static type languages, are hating the JavaScript language due to the lack of structuring and the maintainability problems of JavaScript. Microsoft TypeScript is trying to solve some problems of JavaScript when we are building scalable JavaScript apps. Microsoft TypeScript TypeScript is Microsoft's solution for writing scalable JavaScript programs with the help of Static Types, Interfaces, Modules and Classes along with greater tooling support. TypeScript is a typed superset of JavaScript that compiles to plain JavaScript. This would be more productive for developers who are coming from static type languages. You can write scalable JavaScript apps in TypeScript with more productive and more maintainable manner, and later you can compiles to plain JavaScript which will be run on any browser and any OS. TypeScript will work with browser based JavaScript apps and JavaScript apps that following CommonJS specification. You can use TypeScript for building HTML 5 apps, Node.JS apps, WinRT apps. TypeScript is providing better tooling support with Visual Studio, Sublime Text, Vi, Emacs. Microsoft has open sourced its TypeScript languages on CodePlex at http://typescript.codeplex.com/ Install TypeScript You can install TypeScript compiler as a Node.js package via the NPM or you can install as a Visual Studio 2012 plug-in which will enable you better tooling support within the Visual Studio IDE. Since TypeScript is distributed as a Node.JS package, and it can be installed on other OS such as Linux and MacOS. The following command will install TypeScript compiler via an npm package for node.js npm install –g typescript TypeScript provides a Visual Studio 2012 plug-in as MSI file which will install TypeScript and also provides great tooling support within the Visual Studio, that lets the developers to write TypeScript apps with greater productivity and better maintainability. You can download the Visual Studio plug-in from here Building JavaScript apps with TypeScript You can write typed version of JavaScript programs with TypeScript and then compiles it to plain JavaScript code. The beauty of the TypeScript is that it is already JavaScript and normal JavaScript programs are valid TypeScript programs, which means that you can write normal JavaScript code and can use typed version of JavaScript whenever you want. TypeScript files are using extension .ts and this will be compiled using a compiler named tsc. The following is a sample program written in TypeScript greeter.ts 1: class Greeter { 2: greeting: string; 3: constructor (message: string) { 4: this.greeting = message; 5: } 6: greet() { 7: return "Hello, " + this.greeting; 8: } 9: } 10: 11: var greeter = new Greeter("world"); 12: 13: var button = document.createElement('button') 14: button.innerText = "Say Hello" 15: button.onclick = function() { 16: alert(greeter.greet()) 17: } 18: 19: document.body.appendChild(button) .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The above program is compiling with the TypeScript compiler as shown in the below picture The TypeScript compiler will generate a JavaScript file after compiling the TypeScript program. If your TypeScript programs having any reference to other TypeScript files, it will automatically generate JavaScript files for the each referenced files. The following code block shows the compiled version of plain JavaScript for the above greeter.ts greeter.js 1: var Greeter = (function () { 2: function Greeter(message) { 3: this.greeting = message; 4: } 5: Greeter.prototype.greet = function () { 6: return "Hello, " + this.greeting; 7: }; 8: return Greeter; 9: })(); 10: var greeter = new Greeter("world"); 11: var button = document.createElement('button'); 12: button.innerText = "Say Hello"; 13: button.onclick = function () { 14: alert(greeter.greet()); 15: }; 16: document.body.appendChild(button); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Tooling Support with Visual Studio TypeScript is providing a plug-in for Visual Studio which will provide an excellent support for writing TypeScript programs within the Visual Studio. The following screen shot shows the Visual Studio template for TypeScript apps The following are the few screen shots of Visual Studio IDE for TypeScript apps. Summary TypeScript is Microsoft's solution for writing scalable JavaScript apps which will solve lot of problems involved in larger JavaScript apps. I hope that this solution will attract lot of developers who are really looking for writing maintainable structured code in JavaScript, without losing any productivity. TypeScript lets developers to write JavaScript apps with the help of Static Types, Interfaces, Modules and Classes and also providing better productivity. I am a passionate developer on Node.JS and would definitely try to use TypeScript for building Node.JS apps on the Windows Azure cloud. I am really excited about to writing Node.JS apps by using TypeScript, from my favorite development IDE Visual Studio. You can follow me on twitter at @shijucv

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Top 10 Reasons SQL Developer is Perfect for Oracle Beginners

- by thatjeffsmith

Learning new technologies can be daunting. If you’ve never used a Mac before, you’ll probably be a bit baffled at first. But, you’re probably at least coming from a desktop computing background (Windows), so you common frame of reference. But what if you’re just now learning to use a relational database? Yes, you’ve played with Access a bit, but now your employer or college instructor has charged you with becoming proficient with Oracle database. Here’s 10 reasons why I think Oracle SQL Developer is the perfect vehicle to help get you started. 1. It’s free No need to break into one of these… No start-up costs, no need to wrangle budget dollars from your company. Students don’t have any money after books and lab fees anyway. And most employees don’t like having to ask for ‘special’ software anyway. So avoid all of that and make sure the free stuff doesn’t suit your needs first. Upgrades are available on a regular base, also at no cost, and support is freely available via our public forums. 2. It will run pretty much anywhere Windows – check. OSX (Apple) – check. Unix – check. Linux – check. No need to start up a windows VM to run your Windows-only software in your lab machine. 3. Anyone can install it There’s no installer, no registry to be updated, no admin privs to be obtained. If you can download and extract files to your machine or USB storage device, you can run it. You can be up and running with SQL Developer in under 5 minutes. Here’s a video tutorial to see how to get started. 4. It’s ubiquitous I admit it, I learned a new word yesterday and I wanted an excuse to use it. SQL Developer’s everywhere. It’s had over 2,500,000 downloads in the past year, and is the one of the most downloaded items from OTN. This means if you need help, there’s someone sitting nearby you that can assist, and since they’re in the same tool as you, they’ll be speaking the same language. 5. Simple User Interface Up-up-down-down-Left-right-left-right-A-B-A-B-START will get you 30 lives, but you already knew that, right? You connect, you see your objects, you click on your objects. Or, you can use the worksheet to write your queries and programs in. There’s only one toolbar, and just a few buttons. If you’re like me, video games became less fun when each button had 6 action items mapped to it. I just want the good ole ‘A’, ‘B’, ‘SELECT’, and ‘START’ controls. If you’re new to Oracle, you shouldn’t have the double-workload of learning a new complicated tool as well. 6. It’s not a ‘black box’ Click through your objects, but also get the SQL that drives the GUI As you use the wizards to accomplish tasks for you, you can view the SQL statement being generated on your behalf. Just because you have a GUI, doesn’t mean you’re ceding your responsibility to learn the underlying code that makes the database work. 7. It’s four tools in one It’s not just a query tool. Maybe you need to design a data model first? Or maybe you need to migrate your Sybase ASE database to Oracle for a new project? Or maybe you need to create some reports? SQL Developer does all of that. So once you get comfortable with one part of the tool, the others will be much easier to pick up as your needs change. 8. Great learning resources available Videos, blogs, hands-on learning labs – you name it, we got it. Why wait for someone to train you, when you can train yourself at your own pace? 9. You can use it to teach yourself SQL Instead of being faced with the white-screen-of-panic, you can visually build your queries by dragging and dropping tables and views into the Query Builder. Yes, ‘just like Access’ – only better. And as you build your query, toggle to the Worksheet panel and see the SQL statement. Again, SQL Developer is not a black box. If you prefer to learn by trial and error, the worksheet will attempt to suggest the next bit of your SQL statement with it’s completion insight feature. And if you have syntax errors, those will be highlighted – just like your misspelled words in your favorite word processor. 10. It scales to match your experience level You won’t be a n00b forever. In 6-8 months, when you’re ready to tackle something a bit more complicated, like XML DB or Oracle Spatial, the tool is already there waiting on you. No need to go out and find the ‘advanced’ tool. 11. Wait, you said this was a ‘Top 10′ list? Yes. Yes, I did. I’m using this ‘trick’ to get you to continue reading because I’m going to say something you might not want to hear. Are you ready? Tools won’t replace experience, failure, hard work, and training. Just because you have the keys to the car, doesn’t mean you’re ready to head out on the race track. While SQL Developer reduces the barriers to entry, it does not completely remove them. Many experienced folks simply do not like tools. Rather, they don’t like the people that pick up tools without the know-how to properly use them. If you don’t understand what ‘TRUNCATE’ means, don’t try it out. Try picking up a book first. Of course, it’s very nice to have your own sandbox to play in, so you don’t upset the other children. That’s why I really like our Dev Days Database Virtual Box image. It’s your own database to learn and experiment with.

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Simplify your Ajax code by using jQuery Global Ajax Handlers and ajaxSetup low-level interface

- by hajan

Creating web applications with consistent layout and user interface is very important for your users. In several ASP.NET projects I’ve completed lately, I’ve been using a lot jQuery and jQuery Ajax to achieve rich user experience and seamless interaction between the client and the server. In almost all of them, I took advantage of the nice jQuery global ajax handlers and jQuery ajax functions. Let’s say you build web application which mainly interacts using Ajax post and get to accomplish various operations. As you may already know, you can easily perform Ajax operations using jQuery Ajax low-level method or jQuery $.get, $.post, etc. Simple get example: $.get("/Home/GetData", function (d) { alert(d); }); As you can see, this is the simplest possible way to make Ajax call. What it does in behind is constructing low-level Ajax call by specifying all necessary information for the request, filling with default information set for the required properties such as data type, content type, etc... If you want to have some more control over what is happening with your Ajax Request, you can easily take advantage of the global ajax handlers. In order to register global ajax handlers, jQuery API provides you set of global Ajax methods. You can find all the methods in the following link http://api.jquery.com/category/ajax/global-ajax-event-handlers/, and these are: ajaxComplete ajaxError ajaxSend ajaxStart ajaxStop ajaxSuccess And the low-level ajax interfaces http://api.jquery.com/category/ajax/low-level-interface/: ajax ajaxPrefilter ajaxSetup For global settings, I usually use ajaxSetup combining it with the ajax event handlers. $.ajaxSetup is very good to help you set default values that you will use in all of your future Ajax Requests, so that you won’t need to repeat the same properties all the time unless you want to override the default settings. Mainly, I am using global ajaxSetup function similarly to the following way: $.ajaxSetup({ cache: false, error: function (x, e) { if (x.status == 550) alert("550 Error Message"); else if (x.status == "403") alert("403. Not Authorized"); else if (x.status == "500") alert("500. Internal Server Error"); else alert("Error..."); }, success: function (x) { //do something global on success... } }); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now, you can make ajax call using low-level $.ajax interface and you don’t need to worry about specifying any of the properties we’ve set in the $.ajaxSetup function. So, you can create your own ways to handle various situations when your Ajax requests are occurring. Sometimes, some of your Ajax Requests may take much longer than expected… So, in order to make user friendly UI that will show some progress bar or animated image that something is happening in behind, you can combine ajaxStart and ajaxStop methods to do the same. First of all, add one <div id=”loading” style=”display:none;”> <img src="@Url.Content("~/Content/images/ajax-loader.gif")" alt="Ajax Loader" /></div> anywhere on your Master Layout / Master page (you can download nice ajax loading images from http://ajaxload.info/). Then, add the following two handlers: $(document).ajaxStart(function () { $("#loading").attr("style", "position:absolute; z-index: 1000; top: 0px; "+ "left:0px; text-align: center; display:none; background-color: #ddd; "+ "height: 100%; width: 100%; /* These three lines are for transparency "+ "in all browsers. */-ms-filter:\"progid:DXImageTransform.Microsoft.Alpha(Opacity=50)\";"+ " filter: alpha(opacity=50); opacity:.5;"); $("#loading img").attr("style", "position:relative; top:40%; z-index:5;"); $("#loading").show(); }); $(document).ajaxStop(function () { $("#loading").removeAttr("style"); $("#loading img").removeAttr("style"); $("#loading").hide(); }); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Note: While you can reorganize the style in a more reusable way, since these are global Ajax Start/Stop, it is very possible that you won’t use the same style in other places. With this way, you will see that now for any ajax request in your web site or application, you will have the loading image appearing providing better user experience. What I’ve shown is several useful examples on how to simplify your Ajax code by using Global Ajax Handlers and the low-level AjaxSetup function. Of course, you can do a lot more with the other methods as well. Hope this was helpful. Regards, Hajan

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Adding Volcanos and Options - Earthquake Locator, part 2

- by Bobby Diaz

Since volcanos are often associated with earthquakes, and vice versa, I decided to show recent volcanic activity on the Earthquake Locator map. I am pulling the data from a website created for a joint project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program, found here. They provide a Weekly Volcanic Activity Report as an RSS feed. I started implementing this new functionality by creating a new Volcano entity in the domain model and adding the following to the EarthquakeService class (I also factored out the common reading/parsing helper methods to a separate FeedReader class that can be used by multiple domain service classes): private static readonly string VolcanoFeedUrl = ConfigurationManager.AppSettings["VolcanoFeedUrl"]; /// <summary> /// Gets the volcano data for the previous week. /// </summary> /// <returns>A queryable collection of <see cref="Volcano"/> objects.</returns> public IQueryable<Volcano> GetVolcanos() { var feed = FeedReader.Load(VolcanoFeedUrl); var list = new List<Volcano>(); if ( feed != null ) { foreach ( var item in feed.Items ) { var quake = CreateVolcano(item); if ( quake != null ) { list.Add(quake); } } } return list.AsQueryable(); } /// <summary> /// Creates a <see cref="Volcano"/> object for each item in the RSS feed. /// </summary> /// <param name="item">The RSS item.</param> /// <returns></returns> private Volcano CreateVolcano(SyndicationItem item) { Volcano volcano = null; string title = item.Title.Text; string desc = item.Summary.Text; double? latitude = null; double? longitude = null; FeedReader.GetGeoRssPoint(item, out latitude, out longitude); if ( !String.IsNullOrEmpty(title) ) { title = title.Substring(0, title.IndexOf('-')); } if ( !String.IsNullOrEmpty(desc) ) { desc = String.Join("\n\n", desc .Replace("<p>", "") .Split( new string[] { "</p>" }, StringSplitOptions.RemoveEmptyEntries) .Select(s => s.Trim()) .ToArray()) .Trim(); } if ( latitude != null && longitude != null ) { volcano = new Volcano() { Id = item.Id, Title = title, Description = desc, Url = item.Links.Select(l => l.Uri.OriginalString).FirstOrDefault(), Latitude = latitude.GetValueOrDefault(), Longitude = longitude.GetValueOrDefault() }; } return volcano; } I then added the corresponding LoadVolcanos() method and Volcanos collection to the EarthquakeViewModel class in much the same way I did with the Earthquakes in my previous article in this series. Now that I am starting to add more information to the map, I wanted to give the user some options as to what is displayed and allowing them to choose what gets turned off. I have updated the MainPage.xaml to look like this: <UserControl x:Class="EarthquakeLocator.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:basic="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls" xmlns:bing="clr-namespace:Microsoft.Maps.MapControl;assembly=Microsoft.Maps.MapControl" xmlns:vm="clr-namespace:EarthquakeLocator.ViewModel" mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480" > <UserControl.Resources> <DataTemplate x:Key="EarthquakeTemplate"> <Ellipse Fill="Red" Stroke="Black" StrokeThickness="1" Width="{Binding Size}" Height="{Binding Size}" bing:MapLayer.Position="{Binding Location}" bing:MapLayer.PositionOrigin="Center"> <ToolTipService.ToolTip> <StackPanel> <TextBlock Text="{Binding Title}" FontSize="14" FontWeight="Bold" /> <TextBlock Text="{Binding UtcTime}" /> <TextBlock Text="{Binding LocalTime}" /> <TextBlock Text="{Binding DepthDesc}" /> </StackPanel> </ToolTipService.ToolTip> </Ellipse> </DataTemplate> <DataTemplate x:Key="VolcanoTemplate"> <Polygon Fill="Gold" Stroke="Black" StrokeThickness="1" Points="0,10 5,0 10,10" bing:MapLayer.Position="{Binding Location}" bing:MapLayer.PositionOrigin="Center" MouseLeftButtonUp="Volcano_MouseLeftButtonUp"> <ToolTipService.ToolTip> <StackPanel> <TextBlock Text="{Binding Title}" FontSize="14" FontWeight="Bold" /> <TextBlock Text="Click icon for more information..." /> </StackPanel> </ToolTipService.ToolTip> </Polygon> </DataTemplate> </UserControl.Resources> <UserControl.DataContext> <vm:EarthquakeViewModel AutoLoadData="True" /> </UserControl.DataContext> <Grid x:Name="LayoutRoot"> <bing:Map x:Name="map" CredentialsProvider="--Your-Bing-Maps-Key--" Center="{Binding MapCenter, Mode=TwoWay}" ZoomLevel="{Binding ZoomLevel, Mode=TwoWay}"> <bing:MapItemsControl ItemsSource="{Binding Earthquakes}" ItemTemplate="{StaticResource EarthquakeTemplate}" /> <bing:MapItemsControl ItemsSource="{Binding Volcanos}" ItemTemplate="{StaticResource VolcanoTemplate}" /> </bing:Map> <basic:TabControl x:Name="tabs" VerticalAlignment="Bottom" MaxHeight="25" Opacity="0.7"> <basic:TabItem Margin="90,0,-90,0" MouseLeftButtonUp="TabItem_MouseLeftButtonUp"> <basic:TabItem.Header> <TextBlock x:Name="txtHeader" Text="Options" FontSize="13" FontWeight="Bold" /> </basic:TabItem.Header> <StackPanel Orientation="Horizontal"> <TextBlock Text="Earthquakes:" FontWeight="Bold" Margin="3" /> <StackPanel Margin="3"> <CheckBox Content=" < 4.0" IsChecked="{Binding ShowLt4, Mode=TwoWay}" /> <CheckBox Content="4.0 - 4.9" IsChecked="{Binding Show4s, Mode=TwoWay}" /> <CheckBox Content="5.0 - 5.9" IsChecked="{Binding Show5s, Mode=TwoWay}" /> </StackPanel> <StackPanel Margin="10,3,3,3"> <CheckBox Content="6.0 - 6.9" IsChecked="{Binding Show6s, Mode=TwoWay}" /> <CheckBox Content="7.0 - 7.9" IsChecked="{Binding Show7s, Mode=TwoWay}" /> <CheckBox Content="8.0 +" IsChecked="{Binding ShowGe8, Mode=TwoWay}" /> </StackPanel> <TextBlock Text="Other:" FontWeight="Bold" Margin="50,3,3,3" /> <StackPanel Margin="3"> <CheckBox Content="Volcanos" IsChecked="{Binding ShowVolcanos, Mode=TwoWay}" /> </StackPanel> </StackPanel> </basic:TabItem> </basic:TabControl> </Grid> </UserControl> Notice that I added a VolcanoTemplate that uses a triangle-shaped Polygon to represent the Volcano locations, and I also added a second <bing:MapItemsControl /> tag to the map to bind to the Volcanos collection. The TabControl found below the map houses the options panel that will present the user with several checkboxes so they can filter the different points based on type and other properties (i.e. Magnitude). Initially, the TabItem is collapsed to reduce it's footprint, but the screen shot below shows the options panel expanded to reveal the available settings: I have updated the Source Code and Live Demo to include these new features. Happy Mapping!

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Using Teleriks new LINQ implementation to create OData feeds

This week Telerik released a new LINQ implementation that is simple to use and produces domain models very fast. Built on top of the enterprise grade OpenAccess ORM, you can connect to any database that OpenAccess can connect to such as: SQL Server, MySQL, Oracle, SQL Azure, VistaDB, etc. While this is a separate LINQ implementation from traditional OpenAccess Entites, you can use the visual designer without ever interacting with OpenAccess, however, you can always hook into the advanced ORM features like caching, fetch plan optimization, etc, if needed. Just to show off how easy our LINQ implementation is to use, I will walk you through building an OData feed using Data Services Update for .NET Framework 3.5 SP1. (Memo to Microsoft: P-L-E-A-S-E hire someone from Apple to name your products.) How easy is it? If you have a fast machine, are skilled with the mouse, and type fast, you can do this in about 60 seconds via three easy steps. (I promise in about 2-3 weeks that you can do this in less then 30 seconds. Stay tuned for that.) Step 1 (15-20 seconds): Building your Domain Model In your web project in Visual Studio, right click on the project and select Add|New Item and select Telerik OpenAccess Domain Model as your item template. Give the file a meaningful name as well. Select your database type (SQL Server, SQL Azure, Oracle, MySQL, VistaDB, etc) and build the connection string. If you already have a Visual Studio connection string already saved, this step is trivial. Then select your tables, enter a name for your model and click Finish. In this case I connected to Northwind and selected only Customers, Orders, and Order Details. I named my model NorthwindEntities and will use that in my DataService. Step 2 (20-25 seconds): Adding and Configuring your Data Service In your web project in Visual Studio, right click on the project and select Add|New Item and select ADO .NET Data Service as your item template and name your service. In the code behind for your Data Service you have to make three small changes. Add the name of your Telerik Domain Model (entered in Step 1) as the DataService name (shown on line 6 below as NorthwindEntities) and uncomment line 11 and add a * to show all entities. Optionally if you want to take advantage of the DataService 3.5 updates, add line 13 (and change IDataServiceConfiguration to DataServiceConfiguration in line 9.) 1: using System.Data.Services; 2: using System.Data.Services.Common; 3: 4: namespace Telerik.RLINQ.Astoria.Web 5: { 6: public class NorthwindService : DataService<NorthwindEntities> 7: { 8: //change the IDataServiceConfigurationto DataServiceConfiguration 9: public static void InitializeService(DataServiceConfiguration config) 10: { 11: config.SetEntitySetAccessRule("*", EntitySetRights.All); 12: //take advantage of the "Astoria3.5 Update" features 13: config.DataServiceBehavior.MaxProtocolVersion = DataServiceProtocolVersion.V2; 14: } 15: } 16: } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Step 3 (~30 seconds): Adding the DataServiceKeys You now have to tell your data service what are the primary keys of each entity. To do this you have to create a new code file and create a few partial classes. If you type fast, use copy and paste from your first entity, and use a refactoring productivity tool, you can add these 6-8 lines of code or so in about 30 seconds. This is the most tedious step, but dont worry, Ive bribed some of the developers and our next update will eliminate this step completely. Just create a partial class for each entity you have mapped and add the attribute [DataServiceKey] on top of it along with the keys field name. If you have any complex properties, you will need to make them a primitive type, as I do in line 15. Create this as a separate file, dont manipulate the generated data access classes in case you want to regenerate them again later (even thought that would be much faster.) 1: using System.Data.Services.Common; 2: 3: namespace Telerik.RLINQ.Astoria.Web 4: { 5: [DataServiceKey("CustomerID")] 6: public partial class Customer 7: { 8: } 9: 10: [DataServiceKey("OrderID")] 11: public partial class Order 12: { 13: } 14: 15: [DataServiceKey(new string[] { "OrderID", "ProductID" })] 16: public partial class OrderDetail 17: { 18: } 19: 20: } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Done! Time to run the service. Now, lets run the service! Select the svc file and right click and say View in Browser. You will see your OData service and can interact with it in the browser. Now that you have an OData service set up, you can consume it in one of the many ways that OData is consumed: using LINQ, the Silverlight OData client, Excel PowerPivot, or PhP, etc. Happy Data Servicing! Technorati Tags: Telerik,Astoria,Data Services Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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What to Do When Windows Won’t Boot

- by Chris Hoffman

You turn on your computer one day and Windows refuses to boot — what do you do? “Windows won’t boot” is a common symptom with a variety of causes, so you’ll need to perform some troubleshooting. Modern versions of Windows are better at recovering from this sort of thing. Where Windows XP might have stopped in its tracks when faced with this problem, modern versions of Windows will try to automatically run Startup Repair. First Things First Be sure to think about changes you’ve made recently — did you recently install a new hardware driver, connect a new hardware component to your computer, or open your computer’s case and do something? It’s possible the hardware driver is buggy, the new hardware is incompatible, or that you accidentally unplugged something while working inside your computer. The Computer Won’t Power On At All If your computer won’t power on at all, ensure it’s plugged into a power outlet and that the power connector isn’t loose. If it’s a desktop PC, ensure the power switch on the back of its case — on the power supply — is set to the On position. If it still won’t power on at all, it’s possible you disconnected a power cable inside its case. If you haven’t been messing around inside the case, it’s possible the power supply is dead. In this case, you’ll have to get your computer’s hardware fixed or get a new computer. Be sure to check your computer monitor — if your computer seems to power on but your screen stays black, ensure your monitor is powered on and that the cable connecting it to your computer’s case is plugged in securely at both ends. The Computer Powers On And Says No Bootable Device If your computer is powering on but you get a black screen that says something like “no bootable device” or another sort of “disk error” message, your computer can’t seem to boot from the hard drive that Windows was installed on. Enter your computer’s BIOS or UEFI firmware setup screen and check its boot order setting, ensuring that it’s set to boot from its hard drive. If the hard drive doesn’t appear in the list at all, it’s possible your hard drive has failed and can no longer be booted from. In this case, you may want to insert Windows installation or recovery media and run the Startup Repair operation. This will attempt to make Windows bootable again. For example, if something overwrote your Windows drive’s boot sector, this will repair the boot sector. If the recovery environment won’t load or doesn’t see your hard drive, you likely have a hardware problem. Be sure to check your BIOS or UEFI’s boot order first if the recovery environment won’t load. You can also attempt to manually fix Windows boot loader problems using the fixmbr and fixboot commands. Modern versions of Windows should be able to fix this problem for you with the Startup Repair wizard, so you shouldn’t actually have to run these commands yourself. Windows Freezes or Crashes During Boot If Windows seems to start booting but fails partway through, you may be facing either a software or hardware problem. If it’s a software problem, you may be able to fix it by performing a Startup Repair operation. If you can’t do this from the boot menu, insert a Windows installation disc or recovery disk and use the startup repair tool from there. If this doesn’t help at all, you may want to reinstall Windows or perform a Refresh or Reset on Windows 8. If the computer encounters errors while attempting to perform startup repair or reinstall Windows, or the reinstall process works properly and you encounter the same errors afterwards, you likely have a hardware problem. Windows Starts and Blue Screens or Freezes If Windows crashes or blue-screens on you every time it boots, you may be facing a hardware or software problem. For example, malware or a buggy driver may be loading at boot and causing the crash, or your computer’s hardware may be malfunctioning. To test this, boot your Windows computer in safe mode. In safe mode, Windows won’t load typical hardware drivers or any software that starts automatically at startup. If the computer is stable in safe mode, try uninstalling any recently installed hardware drivers, performing a system restore, and scanning for malware. If you’re lucky, one of these steps may fix your software problem and allow you to boot Windows normally. If your problem isn’t fixed, try reinstalling Windows or performing a Refresh or Reset on Windows 8. This will reset your computer back to its clean, factory-default state. If you’re still experiencing crashes, your computer likely has a hardware problem. Recover Files When Windows Won’t Boot If you have important files that will be lost and want to back them up before reinstalling Windows, you can use a Windows installer disc or Linux live media to recover the files. These run entirely from a CD, DVD, or USB drive and allow you to copy your files to another external media, such as another USB stick or an external hard drive. If you’re incapable of booting a Windows installer disc or Linux live CD, you may need to go into your BIOS or UEFI and change the boot order setting. If even this doesn’t work — or if you can boot from the devices and your computer freezes or you can’t access your hard drive — you likely have a hardware problem. You can try pulling the computer’s hard drive, inserting it into another computer, and recovering your files that way. Following these steps should fix the vast majority of Windows boot issues — at least the ones that are actually fixable. The dark cloud that always hangs over such issues is the possibility that the hard drive or another component in the computer may be failing. Image Credit: Karl-Ludwig G. Poggemann on Flickr, Tzuhsun Hsu on Flickr

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Generate Strongly Typed Observable Events for the Reactive Extensions for .NET (Rx)

- by Bobby Diaz

I must have tried reading through the various explanations and introductions to the new Reactive Extensions for .NET before the concepts finally started sinking in. The article that gave me the ah-ha moment was over on SilverlightShow.net and titled Using Reactive Extensions in Silverlight. The author did a good job comparing the "normal" way of handling events vs. the new "reactive" methods. Admittedly, I still have more to learn about the Rx Framework, but I wanted to put together a sample project so I could start playing with the new Observable and IObservable<T> constructs. I decided to throw together a whiteboard application in Silverlight based on the Drawing with Rx example on the aforementioned article. At the very least, I figured I would learn a thing or two about a new technology, but my real goal is to create a fun application that I can share with the kids since they love drawing and coloring so much! Here is the code sample that I borrowed from the article: var mouseMoveEvent = Observable.FromEvent<MouseEventArgs>(this, "MouseMove"); var mouseLeftButtonDown = Observable.FromEvent<MouseButtonEventArgs>(this, "MouseLeftButtonDown"); var mouseLeftButtonUp = Observable.FromEvent<MouseButtonEventArgs>(this, "MouseLeftButtonUp"); var draggingEvents = from pos in mouseMoveEvent .SkipUntil(mouseLeftButtonDown) .TakeUntil(mouseLeftButtonUp) .Let(mm => mm.Zip(mm.Skip(1), (prev, cur) => new { X2 = cur.EventArgs.GetPosition(this).X, X1 = prev.EventArgs.GetPosition(this).X, Y2 = cur.EventArgs.GetPosition(this).Y, Y1 = prev.EventArgs.GetPosition(this).Y })).Repeat() select pos; draggingEvents.Subscribe(p => { Line line = new Line(); line.Stroke = new SolidColorBrush(Colors.Black); line.StrokeEndLineCap = PenLineCap.Round; line.StrokeLineJoin = PenLineJoin.Round; line.StrokeThickness = 5; line.X1 = p.X1; line.Y1 = p.Y1; line.X2 = p.X2; line.Y2 = p.Y2; this.LayoutRoot.Children.Add(line); }); One thing that was nagging at the back of my mind was having to deal with the event names as strings, as well as the verbose syntax for the Observable.FromEvent<TEventArgs>() method. I came up with a couple of static/helper classes to resolve both issues and also created a T4 template to auto-generate these helpers for any .NET type. Take the following code from the above example: var mouseMoveEvent = Observable.FromEvent<MouseEventArgs>(this, "MouseMove"); var mouseLeftButtonDown = Observable.FromEvent<MouseButtonEventArgs>(this, "MouseLeftButtonDown"); var mouseLeftButtonUp = Observable.FromEvent<MouseButtonEventArgs>(this, "MouseLeftButtonUp"); Turns into this with the new static Events class: var mouseMoveEvent = Events.Mouse.Move.On(this); var mouseLeftButtonDown = Events.Mouse.LeftButtonDown.On(this); var mouseLeftButtonUp = Events.Mouse.LeftButtonUp.On(this); Or better yet, just remove the variable declarations altogether: var draggingEvents = from pos in Events.Mouse.Move.On(this) .SkipUntil(Events.Mouse.LeftButtonDown.On(this)) .TakeUntil(Events.Mouse.LeftButtonUp.On(this)) .Let(mm => mm.Zip(mm.Skip(1), (prev, cur) => new { X2 = cur.EventArgs.GetPosition(this).X, X1 = prev.EventArgs.GetPosition(this).X, Y2 = cur.EventArgs.GetPosition(this).Y, Y1 = prev.EventArgs.GetPosition(this).Y })).Repeat() select pos; The Move, LeftButtonDown and LeftButtonUp members of the Events.Mouse class are readonly instances of the ObservableEvent<TTarget, TEventArgs> class that provide type-safe access to the events via the On() method. Here is the code for the class: using System; using System.Collections.Generic; using System.Linq; namespace System.Linq { /// <summary> /// Represents an event that can be managed via the <see cref="Observable"/> API. /// </summary> /// <typeparam name="TTarget">The type of the target.</typeparam> /// <typeparam name="TEventArgs">The type of the event args.</typeparam> public class ObservableEvent<TTarget, TEventArgs> where TEventArgs : EventArgs { /// <summary> /// Initializes a new instance of the <see cref="ObservableEvent"/> class. /// </summary> /// <param name="eventName">Name of the event.</param> protected ObservableEvent(String eventName) { EventName = eventName; } /// <summary> /// Registers the specified event name. /// </summary> /// <param name="eventName">Name of the event.</param> /// <returns></returns> public static ObservableEvent<TTarget, TEventArgs> Register(String eventName) { return new ObservableEvent<TTarget, TEventArgs>(eventName); } /// <summary> /// Creates an enumerable sequence of event values for the specified target. /// </summary> /// <param name="target">The target.</param> /// <returns></returns> public IObservable<IEvent<TEventArgs>> On(TTarget target) { return Observable.FromEvent<TEventArgs>(target, EventName); } /// <summary> /// Gets or sets the name of the event. /// </summary> /// <value>The name of the event.</value> public string EventName { get; private set; } } } And this is how it's used: /// <summary> /// Categorizes <see cref="ObservableEvents"/> by class and/or functionality. /// </summary> public static partial class Events { /// <summary> /// Implements a set of predefined <see cref="ObservableEvent"/>s /// for the <see cref="System.Windows.System.Windows.UIElement"/> class /// that represent mouse related events. /// </summary> public static partial class Mouse { /// <summary>Represents the MouseMove event.</summary> public static readonly ObservableEvent<UIElement, MouseEventArgs> Move = ObservableEvent<UIElement, MouseEventArgs>.Register("MouseMove"); // additional members omitted... } } The source code contains a static Events class with prefedined members for various categories (Key, Mouse, etc.). There is also an Events.tt template that you can customize to generate additional event categories for any .NET type. All you should have to do is add the name of your class to the types collection near the top of the template: types = new Dictionary<String, Type>() { //{ "Microsoft.Maps.MapControl.Map, Microsoft.Maps.MapControl", null } { "System.Windows.FrameworkElement, System.Windows", null }, { "Whiteboard.MainPage, Whiteboard", null } }; The template is also a bit rough at this point, but at least it generates code that *should* compile. Please let me know if you run into any issues with it. Some people have reported errors when trying to use T4 templates within a Silverlight project, but I was able to get it to work with a little black magic... You can download the source code for this project or play around with the live demo. Just be warned that it is at a very early stage so don't expect to find much today. I plan on adding alot more options like pen colors and sizes, saving, printing, etc. as time permits. HINT: hold down the ESC key to erase! Enjoy! Additional Resources Using Reactive Extensions in Silverlight DevLabs: Reactive Extensions for .NET (Rx) Rx Framework Part III - LINQ to Events - Generating GetEventName() Wrapper Methods using T4

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ASP.NET MVC 2 throws exception for ‘favicon.ico’

- by nmarun

I must be on fire or something – third blog in 2 days… awesome! Before I begin, in case you’re wondering, favicon.ico is the small image that appears to the left of your web address, once the page loads. In order to learn more about MVC or any thing for that matter, it’s better to look at the source itself. Since MVC is open source (at least some part of it is), I started looking at the source code that’s available for download. While doing so, I hit Steve Sanderson’s blog site where he explains in great detail the way to debug your app using ASP.NET MVC source code. For those who are not aware, Steve Sanderson’s book - Pro ASP.NET MVC Framework, is one of the best books to learn about MVC. Alrighty, I followed the article and I hit F5 to debug the default / unchanged MVC project. I put a breakpoint in the DefaultControllerFactory.cs, CreateController() method. To know a little more about this class and the method, read this. Sure enough, the control stopped at the breakpoint and I hit F5 again and the page rendered just fine. But then what’s this? The breakpoint was hit again, as if something else was being requested. I now hovered my mouse over the ‘controllerName’ parameter and it says – favicon.ico. This by itself was more than enough for me to raise my eye-brows, but what happened next just took the ground below my feet. Oh, oh, I’m sorry I’m just typing, no code, no image, so here are a couple of screen captures. The first one shows the request for the Home controller; I get ‘Home’ when I hover over the parameter: And here’s the one that shows the same for call for ‘favicon.ico’. So, I step through the code and when the control reaches line 91 – GetControllerInstance() method, I step in. This is when I had the ‘ground-losing’ experience. Wow, an exception is being thrown for this file and that too in RTM. For some reason MVC thinks, this as a controller and tries to run it through the MvcHandler and it hits this snag. So it seems like this will happen for any MVC 2 site and this did not happen for me in the previous version of MVC. Before I get to how to resolve it, here’s another way of reproducing this exception. Revert back all your changes that you did as mentioned in Steve’s blog above. Now, add a class to your MVC project and call it say, MyControllerFactory and let this inherit from DefaultControllerFactory class. (Read this for details on the DefaultControllerFactory class is and how it is used in a different context). Add an override for the CreateController() method and for the sake of this blog, just copy the same content from the DefaultControllerFactory class. The last step is to tell your MVC app to use the MyControllerFactory class instead of the default one. To do this, go to your Global.asax.cs file and add line 6 of the snippet below: 1: protected void Application_Start() 2: { 3: AreaRegistration.RegisterAllAreas(); 4: 5: RegisterRoutes(RouteTable.Routes); 6: ControllerBuilder.Current.SetControllerFactory(new MyControllerFactory()); 7: } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now, you’re ready to reproduce the issue. Just F5 the project and when you hit the overridden CreateController() method for the second time, this is what it looks like for me: And continuing further gives me the same exception. I believe this is something that MS should fix, as not having ‘favicon.ico’ file will be common for most of the applications. So I think the when you create an MVC project, line 6 should be added by default by Visual Studio itself: 1: public class MvcApplication : System.Web.HttpApplication 2: { 3: public static void RegisterRoutes(RouteCollection routes) 4: { 5: routes.IgnoreRoute("{resource}.axd/{*pathInfo}"); 6: routes.IgnoreRoute("favicon.ico"); 7: 8: routes.MapRoute( 9: "Default", // Route name 10: "{controller}/{action}/{id}", // URL with parameters 11: new { controller = "Home", action = "Index", id = UrlParameter.Optional } // Parameter defaults 12: ); 13: } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } There it is, that’s the solution to avoid the exception altogether. I tried this both IE8 and Firefox browsers and was able to successfully reproduce the error. Hope someone will look at this issue and find a fix. Just before I finish up, I found another ‘bug’, if you want to call it, with Visual Studio 2008. Remember how you could change what browser you want your application to run in by just right clicking on the .aspx file and choosing ‘Browse with…’? Seems like that’s missing when you’re working with an MVC project. In order to test the above bug in the other browser, I had to load a classic ASP.NET project, change the settings and then run my MVC project. Felt kinda ‘icky’, for lack of a better word.

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How to check if a Webcam is broken?

- by user84812

I just bought an Acer Aspire 3830TG, it comes with an integrated 1.3M HD Webcam. Before buying it i tried with a bootable Lubuntu usb stick, everything worked well except for the webcam, which i thought I had to tweak. The thing is that it seems the camera should work with no problems in ubuntu. The driver is detected, I try dmesg | grep uvcvideo and the output is [ 12.226174] uvcvideo: Found UVC 1.00 device 1.3M HD WebCam (058f:b002) [ 12.245553] usbcore: registered new interface driver uvcvideo I've also tried using different software (guvcview is black when camera output is MJPG and turns to funny colors when YU12 or YV12, cheese is always black, camorama is always with funny colors...). I should have checked that it was working properly with the default os (windows) but now it's too late for that. I even booted with a official Ubuntu Quantal distro from the usb pen, and the results are the same. so, my question is: is there any way to check that the camera is righmt or broken? So, if it's broken, at least i can go to the shop, show them that it's really broken and get an external webcam for free, or st like that. cheers. UPDATE 1 Thanks, jrp. I run sudo lsinput, and the output info about my video is the following: /dev/input/event6 bustype : BUS_USB vendor : 0x58f product : 0xb002 version : 2 name : "1.3M HD WebCam" phys : "usb-0000:00:1a.0-1.3/button" bits ev : EV_SYN EV_KEY /dev/input/event7 bustype : BUS_HOST vendor : 0x0 product : 0x6 version : 0 name : "Video Bus" phys : "LNXVIDEO/video/input0" bits ev : EV_SYN EV_KEY With this info, i'm not pretty sure about running the luvcview command. If I run luvcview -d /dev/video0 -L, the output is the following: SDL information: Video driver: x11 A window manager is available Device information: Device path: /dev/video0 { pixelformat = 'YUYV', description = 'YUV 4:2:2 (YUYV)' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 720 } Time interval between frame: 1/7, 1/5, { discrete: width = 1280, height = 800 } Time interval between frame: 1/7, 1/5, { discrete: width = 1280, height = 960 } Time interval between frame: 1/7, 1/5, { discrete: width = 1280, height = 1024 } Time interval between frame: 1/7, 1/5, { pixelformat = 'MJPG', description = 'MJPEG' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 720 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 800 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 960 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 1024 } Time interval between frame: 1/15, 1/10, 1/5, { pixelformat = 'RGB3', description = 'RGB3' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 720 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 800 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 960 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 1024 } Time interval between frame: 1/15, 1/10, 1/5, { pixelformat = 'BGR3', description = 'BGR3' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 720 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 800 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 960 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 1024 } Time interval between frame: 1/15, 1/10, 1/5, { pixelformat = 'YU12', description = 'YU12' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 720 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 800 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 960 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 1024 } Time interval between frame: 1/15, 1/10, 1/5, { pixelformat = 'YV12', description = 'YV12' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 720 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 1280, height = 800 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 960 } Time interval between frame: 1/15, 1/10, 1/5, { discrete: width = 1280, height = 1024 } Time interval between frame: 1/15, 1/10, 1/5, if i run luvcview by itself, the image is funny (blue and red colors, mainly, with myself in negative state). tx

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SortedDictionary and SortedList

- by Simon Cooper

Apart from Dictionary<TKey, TValue>, there's two other dictionaries in the BCL - SortedDictionary<TKey, TValue> and SortedList<TKey, TValue>. On the face of it, these two classes do the same thing - provide an IDictionary<TKey, TValue> interface where the iterator returns the items sorted by the key. So what's the difference between them, and when should you use one rather than the other? (as in my previous post, I'll assume you have some basic algorithm & datastructure knowledge) SortedDictionary We'll first cover SortedDictionary. This is implemented as a special sort of binary tree called a red-black tree. Essentially, it's a binary tree that uses various constraints on how the nodes of the tree can be arranged to ensure the tree is always roughly balanced (for more gory algorithmical details, see the wikipedia link above). What I'm concerned about in this post is how the .NET SortedDictionary is actually implemented. In .NET 4, behind the scenes, the actual implementation of the tree is delegated to a SortedSet<KeyValuePair<TKey, TValue>>. One example tree might look like this: Each node in the above tree is stored as a separate SortedSet<T>.Node object (remember, in a SortedDictionary, T is instantiated to KeyValuePair<TKey, TValue>): class Node { public bool IsRed; public T Item; public SortedSet<T>.Node Left; public SortedSet<T>.Node Right; } The SortedSet only stores a reference to the root node; all the data in the tree is accessed by traversing the Left and Right node references until you reach the node you're looking for. Each individual node can be physically stored anywhere in memory; what's important is the relationship between the nodes. This is also why there is no constructor to SortedDictionary or SortedSet that takes an integer representing the capacity; there are no internal arrays that need to be created and resized. This may seen trivial, but it's an important distinction between SortedDictionary and SortedList that I'll cover later on. And that's pretty much it; it's a standard red-black tree. Plenty of webpages and datastructure books cover the algorithms behind the tree itself far better than I could. What's interesting is the comparions between SortedDictionary and SortedList, which I'll cover at the end. As a side point, SortedDictionary has existed in the BCL ever since .NET 2. That means that, all through .NET 2, 3, and 3.5, there has been a bona-fide sorted set class in the BCL (called TreeSet). However, it was internal, so it couldn't be used outside System.dll. Only in .NET 4 was this class exposed as SortedSet. SortedList Whereas SortedDictionary didn't use any backing arrays, SortedList does. It is implemented just as the name suggests; two arrays, one containing the keys, and one the values (I've just used random letters for the values): The items in the keys array are always guarenteed to be stored in sorted order, and the value corresponding to each key is stored in the same index as the key in the values array. In this example, the value for key item 5 is 'z', and for key item 8 is 'm'. Whenever an item is inserted or removed from the SortedList, a binary search is run on the keys array to find the correct index, then all the items in the arrays are shifted to accomodate the new or removed item. For example, if the key 3 was removed, a binary search would be run to find the array index the item was at, then everything above that index would be moved down by one: and then if the key/value pair {7, 'f'} was added, a binary search would be run on the keys to find the index to insert the new item, and everything above that index would be moved up to accomodate the new item: If another item was then added, both arrays would be resized (to a length of 10) before the new item was added to the arrays. As you can see, any insertions or removals in the middle of the list require a proportion of the array contents to be moved; an O(n) operation. However, if the insertion or removal is at the end of the array (ie the largest key), then it's only O(log n); the cost of the binary search to determine it does actually need to be added to the end (excluding the occasional O(n) cost of resizing the arrays to fit more items). As a side effect of using backing arrays, SortedList offers IList Keys and Values views that simply use the backing keys or values arrays, as well as various methods utilising the array index of stored items, which SortedDictionary does not (and cannot) offer. The Comparison So, when should you use one and not the other? Well, here's the important differences: Memory usage SortedDictionary and SortedList have got very different memory profiles. SortedDictionary... has a memory overhead of one object instance, a bool, and two references per item. On 64-bit systems, this adds up to ~40 bytes, not including the stored item and the reference to it from the Node object. stores the items in separate objects that can be spread all over the heap. This helps to keep memory fragmentation low, as the individual node objects can be allocated wherever there's a spare 60 bytes. In contrast, SortedList... has no additional overhead per item (only the reference to it in the array entries), however the backing arrays can be significantly larger than you need; every time the arrays are resized they double in size. That means that if you add 513 items to a SortedList, the backing arrays will each have a length of 1024. To conteract this, the TrimExcess method resizes the arrays back down to the actual size needed, or you can simply assign list.Capacity = list.Count. stores its items in a continuous block in memory. If the list stores thousands of items, this can cause significant problems with Large Object Heap memory fragmentation as the array resizes, which SortedDictionary doesn't have. Performance Operations on a SortedDictionary always have O(log n) performance, regardless of where in the collection you're adding or removing items. In contrast, SortedList has O(n) performance when you're altering the middle of the collection. If you're adding or removing from the end (ie the largest item), then performance is O(log n), same as SortedDictionary (in practice, it will likely be slightly faster, due to the array items all being in the same area in memory, also called locality of reference). So, when should you use one and not the other? As always with these sort of things, there are no hard-and-fast rules. But generally, if you: need to access items using their index within the collection are populating the dictionary all at once from sorted data aren't adding or removing keys once it's populated then use a SortedList. But if you: don't know how many items are going to be in the dictionary are populating the dictionary from random, unsorted data are adding & removing items randomly then use a SortedDictionary. The default (again, there's no definite rules on these sort of things!) should be to use SortedDictionary, unless there's a good reason to use SortedList, due to the bad performance of SortedList when altering the middle of the collection.

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Changing CSS with jQuery syntax in Silverlight using jLight

- by Timmy Kokke

Lately I’ve ran into situations where I had to change elements or had to request a value in the DOM from Silverlight. jLight, which was introduced in an earlier article, can help with that. jQuery offers great ways to change CSS during runtime. Silverlight can access the DOM, but it isn’t as easy as jQuery. All examples shown in this article can be looked at in this online demo. The code can be downloaded here. Part 1: The easy stuff Selecting and changing properties is pretty straight forward. Setting the text color in all <B> </B> elements can be done using the following code: jQuery.Select("b").Css("color", "red"); The Css() method is an extension method on jQueryObject which is return by the jQuery.Select() method. The Css() method takes to parameters. The first is the Css style property. All properties used in Css can be entered in this string. The second parameter is the value you want to give the property. In this case the property is “color” and it is changed to “red”. To specify which element you want to select you can add a :selector parameter to the Select() method as shown in the next example. jQuery.Select("b:first").Css("font-family", "sans-serif"); The “:first” pseudo-class selector selects only the first element. This example changes the “font-family” property of the first <B></B> element to “sans-serif”. To make use of intellisense in Visual Studio I’ve added a extension methods to help with the pseudo-classes. In the example below the “font-weight” of every “Even” <LI></LI> is set to “bold”. jQuery.Select("li".Even()).Css("font-weight", "bold"); Because the Css() extension method returns a jQueryObject it is possible to chain calls to Css(). The following example show setting the “color”, “background-color” and the “font-size” of all headers in one go. jQuery.Select(":header").Css("color", "#12FF70") .Css("background-color", "yellow") .Css("font-size", "25px"); Part 2: More complex stuff In only a few cases you need to change only one style property. More often you want to change an entire set op style properties all in one go. You could chain a lot of Css() methods together. A better way is to add a class to a stylesheet and define all properties in there. With the AddClass() method you can set a style class to a set of elements. This example shows how to add the “demostyle” class to all <B></B> in the document. jQuery.Select("b").AddClass("demostyle"); Removing the class works in the same way: jQuery.Select("b").RemoveClass("demostyle"); jLight is build for interacting with to the DOM from Silverlight using jQuery. A jQueryObjectCss object can be used to define different sets of style properties in Silverlight. The over 60 most common Css style properties are defined in the jQueryObjectCss class. A string indexer can be used to access all style properties ( CssObject1[“background-color”] equals CssObject1.BackgroundColor). In the code below, two jQueryObjectCss objects are defined and instantiated. private jQueryObjectCss CssObject1; private jQueryObjectCss CssObject2; public Demo2() { CssObject1 = new jQueryObjectCss { BackgroundColor = "Lime", Color="Black", FontSize = "12pt", FontFamily = "sans-serif", FontWeight = "bold", MarginLeft = 150, LineHeight = "28px", Border = "Solid 1px #880000" }; CssObject2 = new jQueryObjectCss { FontStyle = "Italic", FontSize = "48", Color = "#225522" }; InitializeComponent(); } Now instead of chaining to set all different properties you can just pass one of the jQueryObjectCss objects to the Css() method. In this case all <LI></LI> elements are set to match this object. jQuery.Select("li").Css(CssObject1); When using the jQueryObjectCss objects chaining is still possible. In the following example all headers are given a blue backgroundcolor and the last is set to match CssObject2. jQuery.Select(":header").Css(new jQueryObjectCss{BackgroundColor = "Blue"}) .Eq(-1).Css(CssObject2); Part 3: The fun stuff Having Silverlight call JavaScript and than having JavaScript to call Silverlight requires a lot of plumbing code. Everything has to be registered and strings are passed back and forth to execute the JavaScript. jLight makes this kind of stuff so easy, it becomes fun to use. In a lot of situations jQuery can call a function to decide what to do, setting a style class based on complex expressions for example. jLight can do the same, but the callback methods are defined in Silverlight. This example calls the function() method for each <LI></LI> element. The callback method has to take a jQueryObject, an integer and a string as parameters. In this case jLight differs a bit from the actual jQuery implementation. jQuery uses only the index and the className parameters. A jQueryObject is added to make it simpler to access the attributes and properties of the element. If the text of the listitem starts with a ‘D’ or an ‘M’ the class is set. Otherwise null is returned and nothing happens. private void button1_Click(object sender, RoutedEventArgs e) { jQuery.Select("li").AddClass(function); } private string function(jQueryObject obj, int index, string className) { if (obj.Text[0] == 'D' || obj.Text[0] == 'M') return "demostyle"; return null; } The last thing I would like to demonstrate uses even more Silverlight and less jLight, but demonstrates the power of the combination. Animating a style property using a Storyboard with easing functions. First a dependency property is defined. In this case it is a double named Intensity. By handling the changed event the color is set using jQuery. public double Intensity { get { return (double)GetValue(IntensityProperty); } set { SetValue(IntensityProperty, value); } } public static readonly DependencyProperty IntensityProperty = DependencyProperty.Register("Intensity", typeof(double), typeof(Demo3), new PropertyMetadata(0.0, IntensityChanged)); private static void IntensityChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { var i = (byte)(double)e.NewValue; jQuery.Select("span").Css("color", string.Format("#{0:X2}{0:X2}{0:X2}", i)); } An animation has to be created. This code defines a Storyboard with one keyframe that uses a bounce ease as an easing function. The animation is set to target the Intensity dependency property defined earlier. private Storyboard CreateAnimation(double value) { Storyboard storyboard = new Storyboard(); var da = new DoubleAnimationUsingKeyFrames(); var d = new EasingDoubleKeyFrame { EasingFunction = new BounceEase(), KeyTime = KeyTime.FromTimeSpan(TimeSpan.FromSeconds(1.0)), Value = value }; da.KeyFrames.Add(d); Storyboard.SetTarget(da, this); Storyboard.SetTargetProperty(da, new PropertyPath(Demo3.IntensityProperty)); storyboard.Children.Add(da); return storyboard; } Initially the Intensity is set to 128 which results in a gray color. When one of the buttons is pressed, a new animation is created an played. One to animate to black, and one to animate to white. public Demo3() { InitializeComponent(); Intensity = 128; } private void button2_Click(object sender, RoutedEventArgs e) { CreateAnimation(255).Begin(); } private void button3_Click(object sender, RoutedEventArgs e) { CreateAnimation(0).Begin(); } Conclusion As you can see jLight can make the life of a Silverlight developer a lot easier when accessing the DOM. Almost all jQuery functions that are defined in jLight use the same constructions as described above. I’ve tried to stay as close as possible to the real jQuery. Having JavaScript perform callbacks to Silverlight using jLight will be described in more detail in a future tutorial about AJAX or eventing.

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Setting useLegacyV2RuntimeActivationPolicy At Runtime

- by Reed

Version 4.0 of the .NET Framework included a new CLR which is almost entirely backwards compatible with the 2.0 version of the CLR. However, by default, mixed-mode assemblies targeting .NET 3.5sp1 and earlier will fail to load in a .NET 4 application. Fixing this requires setting useLegacyV2RuntimeActivationPolicy in your app.Config for the application. While there are many good reasons for this decision, there are times when this is extremely frustrating, especially when writing a library. As such, there are (rare) times when it would be beneficial to set this in code, at runtime, as well as verify that it’s running correctly prior to receiving a FileLoadException. Typically, loading a pre-.NET 4 mixed mode assembly is handled simply by changing your app.Config file, and including the relevant attribute in the startup element: <?xml version="1.0" encoding="utf-8" ?> <configuration> <startup useLegacyV2RuntimeActivationPolicy="true"> <supportedRuntime version="v4.0"/> </startup> </configuration> .csharpcode { background-color: #ffffff; font-family: consolas, "Courier New", courier, monospace; color: black; font-size: small } .csharpcode pre { background-color: #ffffff; font-family: consolas, "Courier New", courier, monospace; color: black; font-size: small } .csharpcode pre { margin: 0em } .csharpcode .rem { color: #008000 } .csharpcode .kwrd { color: #0000ff } .csharpcode .str { color: #006080 } .csharpcode .op { color: #0000c0 } .csharpcode .preproc { color: #cc6633 } .csharpcode .asp { background-color: #ffff00 } .csharpcode .html { color: #800000 } .csharpcode .attr { color: #ff0000 } .csharpcode .alt { background-color: #f4f4f4; margin: 0em; width: 100% } .csharpcode .lnum { color: #606060 } This causes your application to run correctly, and load the older, mixed-mode assembly without issues. For full details on what’s happening here and why, I recommend reading Mark Miller’s detailed explanation of this attribute and the reasoning behind it. Before I show any code, let me say: I strongly recommend using the official approach of using app.config to set this policy. That being said, there are (rare) times when, for one reason or another, changing the application configuration file is less than ideal. While this is the supported approach to handling this issue, the CLR Hosting API includes a means of setting this programmatically via the ICLRRuntimeInfo interface. Normally, this is used if you’re hosting the CLR in a native application in order to set this, at runtime, prior to loading the assemblies. However, the F# Samples include a nice trick showing how to load this API and bind this policy, at runtime. This was required in order to host the Managed DirectX API, which is built against an older version of the CLR. This is fairly easy to port to C#. Instead of a direct port, I also added a little addition – by trapping the COM exception received if unable to bind (which will occur if the 2.0 CLR is already bound), I also allow a runtime check of whether this property was setup properly: public static class RuntimePolicyHelper { public static bool LegacyV2RuntimeEnabledSuccessfully { get; private set; } static RuntimePolicyHelper() { ICLRRuntimeInfo clrRuntimeInfo = (ICLRRuntimeInfo)RuntimeEnvironment.GetRuntimeInterfaceAsObject( Guid.Empty, typeof(ICLRRuntimeInfo).GUID); try { clrRuntimeInfo.BindAsLegacyV2Runtime(); LegacyV2RuntimeEnabledSuccessfully = true; } catch (COMException) { // This occurs with an HRESULT meaning // "A different runtime was already bound to the legacy CLR version 2 activation policy." LegacyV2RuntimeEnabledSuccessfully = false; } } [ComImport] [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)] [Guid("BD39D1D2-BA2F-486A-89B0-B4B0CB466891")] private interface ICLRRuntimeInfo { void xGetVersionString(); void xGetRuntimeDirectory(); void xIsLoaded(); void xIsLoadable(); void xLoadErrorString(); void xLoadLibrary(); void xGetProcAddress(); void xGetInterface(); void xSetDefaultStartupFlags(); void xGetDefaultStartupFlags(); [MethodImpl(MethodImplOptions.InternalCall, MethodCodeType = MethodCodeType.Runtime)] void BindAsLegacyV2Runtime(); } } Using this, it’s possible to not only set this at runtime, but also verify, prior to loading your mixed mode assembly, whether this will succeed. In my case, this was quite useful – I am working on a library purely for internal use which uses a numerical package that is supplied with both a completely managed as well as a native solver. The native solver uses a CLR 2 mixed-mode assembly, but is dramatically faster than the pure managed approach. By checking RuntimePolicyHelper.LegacyV2RuntimeEnabledSuccessfully at runtime, I can decide whether to enable the native solver, and only do so if I successfully bound this policy. There are some tricks required here – To enable this sort of fallback behavior, you must make these checks in a type that doesn’t cause the mixed mode assembly to be loaded. In my case, this forced me to encapsulate the library I was using entirely in a separate class, perform the check, then pass through the required calls to that class. Otherwise, the library will load before the hosting process gets enabled, which in turn will fail. This code will also, of course, try to enable the runtime policy before the first time you use this class – which typically means just before the first time you check the boolean value. As a result, checking this early on in the application is more likely to allow it to work. Finally, if you’re using a library, this has to be called prior to the 2.0 CLR loading. This will cause it to fail if you try to use it to enable this policy in a plugin for most third party applications that don’t have their app.config setup properly, as they will likely have already loaded the 2.0 runtime. As an example, take a simple audio player. The code below shows how this can be used to properly, at runtime, only use the “native” API if this will succeed, and fallback (or raise a nicer exception) if this will fail: public class AudioPlayer { private IAudioEngine audioEngine; public AudioPlayer() { if (RuntimePolicyHelper.LegacyV2RuntimeEnabledSuccessfully) { // This will load a CLR 2 mixed mode assembly this.audioEngine = new AudioEngineNative(); } else { this.audioEngine = new AudioEngineManaged(); } } public void Play(string filename) { this.audioEngine.Play(filename); } } Now – the warning: This approach works, but I would be very hesitant to use it in public facing production code, especially for anything other than initializing your own application. While this should work in a library, using it has a very nasty side effect: you change the runtime policy of the executing application in a way that is very hidden and non-obvious.

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SQL University: What and why of database refactoring

- by Mladen Prajdic

This is a post for a great idea called SQL University started by Jorge Segarra also famously known as SqlChicken on Twitter. It’s a collection of blog posts on different database related topics contributed by several smart people all over the world. So this week is mine and we’ll be talking about database testing and refactoring. In 3 posts we’ll cover: SQLU part 1 - What and why of database testing SQLU part 2 - What and why of database refactoring SQLU part 3 - Tools of the trade This is a second part of the series and in it we’ll take a look at what database refactoring is and why do it. Why refactor a database To know why refactor we first have to know what refactoring actually is. Code refactoring is a process where we change module internals in a way that does not change that module’s input/output behavior. For successful refactoring there is one crucial thing we absolutely must have: Tests. Automated unit tests are the only guarantee we have that we haven’t broken the input/output behavior before refactoring. If you haven’t go back ad read my post on the matter. Then start writing them. Next thing you need is a code module. Those are views, UDFs and stored procedures. By having direct table access we can kiss fast and sweet refactoring good bye. One more point to have a database abstraction layer. And no, ORM’s don’t fall into that category. But also know that refactoring is NOT adding new functionality to your code. Many have fallen into this trap. Don’t be one of them and resist the lure of the dark side. And it’s a strong lure. We developers in general love to add new stuff to our code, but hate fixing our own mistakes or changing existing code for no apparent reason. To be a good refactorer one needs discipline and focus. Now we know that refactoring is all about changing inner workings of existing code. This can be due to performance optimizations, changing internal code workflows or some other reason. This is a typical black box scenario to the outside world. If we upgrade the car engine it still has to drive on the road (preferably faster) and not fly (no matter how cool that would be). Also be aware that white box tests will break when we refactor. What to refactor in a database Refactoring databases doesn’t happen that often but when it does it can include a lot of stuff. Let us look at a few common cases. Adding or removing database schema objects Adding, removing or changing table columns in any way, adding constraints, keys, etc… All of these can be counted as internal changes not visible to the data consumer. But each of these carries a potential input/output behavior change. Dropping a column can result in views not working anymore or stored procedure logic crashing. Adding a unique constraint shows duplicated data that shouldn’t exist. Foreign keys break a truncate table command executed from an application that runs once a month. All these scenarios are very real and can happen. With the proper database abstraction layer fully covered with black box tests we can make sure something like that does not happen (hopefully at all). Changing physical structures Physical structures include heaps, indexes and partitions. We can pretty much add or remove those without changing the data returned by the database. But the performance can be affected. So here we use our performance tests. We do have them, right? Just by adding a single index we can achieve orders of magnitude performance improvement. Won’t that make users happy? But what if that index causes our write operations to crawl to a stop. again we have to test this. There are a lot of things to think about and have tests for. Without tests we can’t do successful refactoring! Fixing bad code We all have some bad code in our systems. We usually refer to that code as code smell as they violate good coding practices. Examples of such code smells are SQL injection, use of SELECT *, scalar UDFs or cursors, etc… Each of those is huge code smell and can result in major code changes. Take SELECT * from example. If we remove a column from a table the client using that SELECT * statement won’t have a clue about that until it runs. Then it will gracefully crash and burn. Not to mention the widely unknown SELECT * view refresh problem that Tomas LaRock (@SQLRockstar on Twitter) and Colin Stasiuk (@BenchmarkIT on Twitter) talk about in detail. Go read about it, it’s informative. Refactoring this includes replacing the * with column names and most likely change to application using the database. Breaking apart huge stored procedures Have you ever seen seen a stored procedure that was 2000 lines long? I have. It’s not pretty. It hurts the eyes and sucks the will to live the next 10 minutes. They are a maintenance nightmare and turn into things no one dares to touch. I’m willing to bet that 100% of time they don’t have a single test on them. Large stored procedures (and functions) are a clear sign that they contain business logic. General opinion on good database coding practices says that business logic has no business in the database. That’s the applications part. Refactoring such behemoths requires writing lots of edge case tests for the stored procedure input/output behavior and then start to refactor it. First we split the logic inside into smaller parts like new stored procedures and UDFs. Those then get called from the master stored procedure. Once we’ve successfully modularized the database code it’s best to transfer that logic into the applications consuming it. This only leaves the stored procedure with common data manipulation logic. Of course this isn’t always possible so having a plethora of performance and behavior unit tests is absolutely necessary to confirm we’ve actually improved the codebase in some way. Refactoring is not a popular chore amongst developers or managers. The former don’t like fixing old code, the latter can’t see the financial benefit. Remember how we talked about being lousy at estimating future costs in the previous post? But there comes a time when it must be done. Hopefully I’ve given you some ideas how to get started. In the last post of the series we’ll take a look at the tools to use and an example of testing and refactoring.

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