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  • Project Navigation and File Nesting in ASP.NET MVC Projects

    - by Rick Strahl
    More and more I’m finding myself getting lost in the files in some of my larger Web projects. There’s so much freaking content to deal with – HTML Views, several derived CSS pages, page level CSS, script libraries, application wide scripts and page specific script files etc. etc. Thankfully I use Resharper and the Ctrl-T Go to Anything which autocompletes you to any file, type, member rapidly. Awesome except when I forget – or when I’m not quite sure of the name of what I’m looking for. Project navigation is still important. Sometimes while working on a project I seem to have 30 or more files open and trying to locate another new file to open in the solution often ends up being a mental exercise – “where did I put that thing?” It’s those little hesitations that tend to get in the way of workflow frequently. To make things worse most NuGet packages for client side frameworks and scripts, dump stuff into folders that I generally don’t use. I’ve never been a fan of the ‘Content’ folder in MVC which is just an empty layer that doesn’t serve much of a purpose. It’s usually the first thing I nuke in every MVC project. To me the project root is where the actual content for a site goes – is there really a need to add another folder to force another path into every resource you use? It’s ugly and also inefficient as it adds additional bytes to every resource link you embed into a page. Alternatives I’ve been playing around with different folder layouts recently and found that moving my cheese around has actually made project navigation much easier. In this post I show a couple of things I’ve found useful and maybe you find some of these useful as well or at least get some ideas what can be changed to provide better project flow. The first thing I’ve been doing is add a root Code folder and putting all server code into that. I’m a big fan of treating the Web project root folder as my Web root folder so all content comes from the root without unneeded nesting like the Content folder. By moving all server code out of the root tree (except for Code) the root tree becomes a lot cleaner immediately as you remove Controllers, App_Start, Models etc. and move them underneath Code. Yes this adds another folder level for server code, but it leaves only code related things in one place that’s easier to jump back and forth in. Additionally I find myself doing a lot less with server side code these days, more with client side code so I want the server code separated from that. The root folder itself then serves as the root content folder. Specifically I have the Views folder below it, as well as the Css and Scripts folders which serve to hold only common libraries and global CSS and Scripts code. These days of building SPA style application, I also tend to have an App folder there where I keep my application specific JavaScript files, as well as HTML View templates for client SPA apps like Angular. Here’s an example of what this looks like in a relatively small project: The goal is to keep things that are related together, so I don’t end up jumping around so much in the solution to get to specific project items. The Code folder may irk some of you and hark back to the days of the App_Code folder in non Web-Application projects, but these days I find myself messing with a lot less server side code and much more with client side files – HTML, CSS and JavaScript. Generally I work on a single controller at a time – once that’s open it’s open that’s typically the only server code I work with regularily. Business logic lives in another project altogether, so other than the controller and maybe ViewModels there’s not a lot of code being accessed in the Code folder. So throwing that off the root and isolating seems like an easy win. Nesting Page specific content In a lot of my existing applications that are pure server side MVC application perhaps with some JavaScript associated with them , I tend to have page level javascript and css files. For these types of pages I actually prefer the local files stored in the same folder as the parent view. So typically I have a .css and .js files with the same name as the view in the same folder. This looks something like this: In order for this to work you have to also make a configuration change inside of the /Views/web.config file, as the Views folder is blocked with the BlockViewHandler that prohibits access to content from that folder. It’s easy to fix by changing the path from * to *.cshtml or *.vbhtml so that view retrieval is blocked:<system.webServer> <handlers> <remove name="BlockViewHandler"/> <add name="BlockViewHandler" path="*.cshtml" verb="*" preCondition="integratedMode" type="System.Web.HttpNotFoundHandler" /> </handlers> </system.webServer> With this in place, from inside of your Views you can then reference those same resources like this:<link href="~/Views/Admin/QuizPrognosisItems.css" rel="stylesheet" /> and<script src="~/Views/Admin/QuizPrognosisItems.js"></script> which works fine. JavaScript and CSS files in the Views folder deploy just like the .cshtml files do and can be referenced from this folder as well. Making this happen is not really as straightforward as it should be with just Visual Studio unfortunately, as there’s no easy way to get the file nesting from the VS IDE directly (you have to modify the .csproj file). However, Mads Kristensen has a nice Visual Studio Add-in that provides file nesting via a short cut menu option. Using this you can select each of the ‘child’ files and then nest them under a parent file. In the case above I select the .js and .css files and nest them underneath the .cshtml view. I was even toying with the idea of throwing the controller.cs files into the Views folder, but that’s maybe going a little too far :-) It would work however as Visual Studio doesn’t publish .cs files and the compiler doesn’t care where the files live. There are lots of options and if you think that would make life easier it’s another option to help group related things together. Are there any downside to this? Possibly – if you’re using automated minification/packaging tools like ASP.NET Bundling or Grunt/Gulp with Uglify, it becomes a little harder to group script and css files for minification as you may end up looking in multiple folders instead of a single folder. But – again that’s a one time configuration step that’s easily handled and much less intrusive then constantly having to search for files in your project. Client Side Folders The particular project shown above in the screen shots above is a traditional server side ASP.NET MVC application with most content rendered into server side Razor pages. There’s a fair amount of client side stuff happening on these pages as well – specifically several of these pages are self contained single page Angular applications that deal with 1 or maybe 2 separate views and the layout I’ve shown above really focuses on the server side aspect where there are Razor views with related script and css resources. For applications that are more client centric and have a lot more script and HTML template based content I tend to use the same layout for the server components, but the client side code can often be broken out differently. In SPA type applications I tend to follow the App folder approach where all the application pieces that make the SPA applications end up below the App folder. Here’s what that looks like for me – here this is an AngularJs project: In this case the App folder holds both the application specific js files, and the partial HTML views that get loaded into this single SPA page application. In this particular Angular SPA application that has controllers linked to particular partial views, I prefer to keep the script files that are associated with the views – Angular Js Controllers in this case – with the actual partials. Again I like the proximity of the view with the main code associated with the view, because 90% of the UI application code that gets written is handled between these two files. This approach works well, but only if controllers are fairly closely aligned with the partials. If you have many smaller sub-controllers or lots of directives where the alignment between views and code is more segmented this approach starts falling apart and you’ll probably be better off with separate folders in js folder. Following Angular conventions you’d have controllers/directives/services etc. folders. Please note that I’m not saying any of these ways are right or wrong  – this is just what has worked for me and why! Skipping Project Navigation altogether with Resharper I’ve talked a bit about project navigation in the project tree, which is a common way to navigate and which we all use at least some of the time, but if you use a tool like Resharper – which has Ctrl-T to jump to anything, you can quickly navigate with a shortcut key and autocomplete search. Here’s what Resharper’s jump to anything looks like: Resharper’s Goto Anything box lets you type and quick search over files, classes and members of the entire solution which is a very fast and powerful way to find what you’re looking for in your project, by passing the solution explorer altogether. As long as you remember to use (which I sometimes don’t) and you know what you’re looking for it’s by far the quickest way to find things in a project. It’s a shame that this sort of a simple search interface isn’t part of the native Visual Studio IDE. Work how you like to work Ultimately it all comes down to workflow and how you like to work, and what makes *you* more productive. Following pre-defined patterns is great for consistency, as long as they don’t get in the way you work. A lot of the default folder structures in Visual Studio for ASP.NET MVC were defined when things were done differently. These days we’re dealing with a lot more diverse project content than when ASP.NET MVC was originally introduced and project organization definitely is something that can get in the way if it doesn’t fit your workflow. So take a look and see what works well and what might benefit from organizing files differently. As so many things with ASP.NET, as things evolve and tend to get more complex I’ve found that I end up fighting some of the conventions. The good news is that you don’t have to follow the conventions and you have the freedom to do just about anything that works for you. Even though what I’ve shown here diverges from conventions, I don’t think anybody would stumble over these relatively minor changes and not immediately figure out where things live, even in larger projects. But nevertheless think long and hard before breaking those conventions – if there isn’t a good reason to break them or the changes don’t provide improved workflow then it’s not worth it. Break the rules, but only if there’s a quantifiable benefit. You may not agree with how I’ve chosen to divert from the standard project structures in this article, but maybe it gives you some ideas of how you can mix things up to make your existing project flow a little nicer and make it easier to navigate for your environment. © Rick Strahl, West Wind Technologies, 2005-2014Posted in ASP.NET  MVC   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • The Red Gate and .NET Reflector Debacle

    - by Rick Strahl
    About a month ago Red Gate – the company who owns the NET Reflector tool most .NET devs use at one point or another – decided to change their business model for Reflector and take the product from free to a fully paid for license model. As a bit of history: .NET Reflector was originally created by Lutz Roeder as a free community tool to inspect .NET assemblies. Using Reflector you can examine the types in an assembly, drill into type signatures and quickly disassemble code to see how a particular method works.  In case you’ve been living under a rock and you’ve never looked at Reflector, here’s what it looks like drilled into an assembly from disk with some disassembled source code showing: Note that you get tons of information about each element in the tree, and almost all related types and members are clickable both in the list and source view so it’s extremely easy to navigate and follow the code flow even in this static assembly only view. For many year’s Lutz kept the the tool up to date and added more features gradually improving an already amazing tool and making it better. Then about two and a half years ago Red Gate bought the tool from Lutz. A lot of ruckus and noise ensued in the community back then about what would happen with the tool and… for the most part very little did. Other than the incessant update notices with prominent Red Gate promo on them life with Reflector went on. The product didn’t die and and it didn’t go commercial or to a charge model. When .NET 4.0 came out it still continued to work mostly because the .NET feature set doesn’t drastically change how types behave.  Then a month back Red Gate started making noise about a new Version Version 7 which would be commercial. No more free version - and a shit storm broke out in the community. Now normally I’m not one to be critical of companies trying to make money from a product, much less for a product that’s as incredibly useful as Reflector. There isn’t day in .NET development that goes by for me where I don’t fire up Reflector. Whether it’s for examining the innards of the .NET Framework, checking out third party code, or verifying some of my own code and resources. Even more so recently I’ve been doing a lot of Interop work with a non-.NET application that needs to access .NET components and Reflector has been immensely valuable to me (and my clients) if figuring out exact type signatures required to calling .NET components in assemblies. In short Reflector is an invaluable tool to me. Ok, so what’s the problem? Why all the fuss? Certainly the $39 Red Gate is trying to charge isn’t going to kill any developer. If there’s any tool in .NET that’s worth $39 it’s Reflector, right? Right, but that’s not the problem here. The problem is how Red Gate went about moving the product to commercial which borders on the downright bizarre. It’s almost as if somebody in management wrote a slogan: “How can we piss off the .NET community in the most painful way we can?” And that it seems Red Gate has a utterly succeeded. People are rabid, and for once I think that this outrage isn’t exactly misplaced. Take a look at the message thread that Red Gate dedicated from a link off the download page. Not only is Version 7 going to be a paid commercial tool, but the older versions of Reflector won’t be available any longer. Not only that but older versions that are already in use also will continually try to update themselves to the new paid version – which when installed will then expire unless registered properly. There have also been reports of Version 6 installs shutting themselves down and failing to work if the update is refused (I haven’t seen that myself so not sure if that’s true). In other words Red Gate is trying to make damn sure they’re getting your money if you attempt to use Reflector. There’s a lot of temptation there. Think about the millions of .NET developers out there and all of them possibly upgrading – that’s a nice chunk of change that Red Gate’s sitting on. Even with all the community backlash these guys are probably making some bank right now just because people need to get life to move on. Red Gate also put up a Feedback link on the download page – which not surprisingly is chock full with hate mail condemning the move. Oddly there’s not a single response to any of those messages by the Red Gate folks except when it concerns license questions for the full version. It puzzles me what that link serves for other yet than another complete example of failure to understand how to handle customer relations. There’s no doubt that that all of this has caused some serious outrage in the community. The sad part though is that this could have been handled so much less arrogantly and without pissing off the entire community and causing so much ill-will. People are pissed off and I have no doubt that this negative publicity will show up in the sales numbers for their other products. I certainly hope so. Stupidity ought to be painful! Why do Companies do boneheaded stuff like this? Red Gate’s original decision to buy Reflector was hotly debated but at that the time most of what would happen was mostly speculation. But I thought it was a smart move for any company that is in need of spreading its marketing message and corporate image as a vendor in the .NET space. Where else do you get to flash your corporate logo to hordes of .NET developers on a regular basis?  Exploiting that marketing with some goodwill of providing a free tool breeds positive feedback that hopefully has a good effect on the company’s visibility and the products it sells. Instead Red Gate seems to have taken exactly the opposite tack of corporate bullying to try to make a quick buck – and in the process ruined any community goodwill that might have come from providing a service community for free while still getting valuable marketing. What’s so puzzling about this boneheaded escapade is that the company doesn’t need to resort to underhanded tactics like what they are trying with Reflector 7. The tools the company makes are very good. I personally use SQL Compare, Sql Data Compare and ANTS Profiler on a regular basis and all of these tools are essential in my toolbox. They certainly work much better than the tools that are in the box with Visual Studio. Chances are that if Reflector 7 added useful features I would have been more than happy to shell out my $39 to upgrade when the time is right. It’s Expensive to give away stuff for Free At the same time, this episode shows some of the big problems that come with ‘free’ tools. A lot of organizations are realizing that giving stuff away for free is actually quite expensive and the pay back is often very intangible if any at all. Those that rely on donations or other voluntary compensation find that they amount contributed is absolutely miniscule as to not matter at all. Yet at the same time I bet most of those clamouring the loudest on that Red Gate Reflector feedback page that Reflector won’t be free anymore probably have NEVER made a donation to any open source project or free tool ever. The expectation of Free these days is just too great – which is a shame I think. There’s a lot to be said for paid software and having somebody to hold to responsible to because you gave them some money. There’s an incentive –> payback –> responsibility model that seems to be missing from free software (not all of it, but a lot of it). While there certainly are plenty of bad apples in paid software as well, money tends to be a good motivator for people to continue working and improving products. Reasons for giving away stuff are many but often it’s a naïve desire to share things when things are simple. At first it might be no problem to volunteer time and effort but as products mature the fun goes out of it, and as the reality of product maintenance kicks in developers want to get something back for the time and effort they’re putting in doing non-glamorous work. It’s then when products die or languish and this is painful for all to watch. For Red Gate however, I think there was always a pretty good payback from the Reflector acquisition in terms of marketing: Visibility and possible positioning of their products although they seemed to have mostly ignored that option. On the other hand they started this off pretty badly even 2 and a half years back when they aquired Reflector from Lutz with the same arrogant attitude that is evident in the latest episode. You really gotta wonder what folks are thinking in management – the sad part is from advance emails that were circulating, they were fully aware of the shit storm they were inciting with this and I suspect they are banking on the sheer numbers of .NET developers to still make them a tidy chunk of change from upgrades… Alternatives are coming For me personally the single license isn’t a problem, but I actually have a tool that I sell (an interop Web Service proxy generation tool) to customers and one of the things I recommend to use with has been Reflector to view assembly information and to find which Interop classes to instantiate from the non-.NET environment. It’s been nice to use Reflector for this with its small footprint and zero-configuration installation. But now with V7 becoming a paid tool that option is not going to be available anymore. Luckily it looks like the .NET community is jumping to it and trying to fill the void. Amidst the Red Gate outrage a new library called ILSpy has sprung up and providing at least some of the core functionality of Reflector with an open source library. It looks promising going forward and I suspect there will be a lot more support and interest to support this project now that Reflector has gone over to the ‘dark side’…© Rick Strahl, West Wind Technologies, 2005-2011

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  • Contract Work - Lessons Learned

    - by samerpaul
    I thought I would write a post of a different nature today, but still relevant to the tech world. I do a lot of contract jobs myself and really enjoy it. It's nice to keep jumping from project to project, and not having to go to an office or keep regular hours, etc. I really enjoy it. I have learned a lot in the past few years of doing it (both from experience and from help given to me from others, and the internet) so I thought I'd share some of that knowledge/experience today.So here's my own personal "lesson's learned" that hopefully will help you if you find yourself doing contract work:Should I take the job?Ok, so this is the first step. Assuming you were given sufficient information about what they want, then you should really think about what you're capable of doing and whether or not you should take this job. Personally, my rule is, if I know it's possible, I'll say yes, even if I don't yet know how to do it. That's because the internet is such a great help, it would be rare to run into an issue that you can't figure out with some help. So if your clients are asking for something that you don't yet know how to program, but you know you can do it on the platform then go for it. How else are you going to learn?Use this rule with some limitation, however. If you're really lacking the expertise or foundation in something, then unless you have tons of time to complete the project, then I wouldn't say yes. For example, I haven't personally done any 3d/openGL programming yet so I wouldn't say yes to a project that extensively uses it. OK, so I want the job, but how much do I charge?This part can be tricky. There is no set formula really, but I have some tips for pricing that will hopefully give you a better idea on how to confidently ask your price and have them accept. Here are some personal guidelinesHow much time do you have to complete the project? If it's shorter than average, then charge more. You can even make a subtle note about this (or not so subtle if they still don't get it.) If it seems too short of a time (i.e. near impossible to complete), be sure to say that. It looks bad to promise a time that you can't keep--and it makes it less likely for them to return to you for work.Your Hourly rate: How long have you been working in that language? Do you have existing projects to back you up? Or previous contacts that can vouch for your work? Are there very few people with your particular skill set? All of these things will lend themselves to setting an hourly rate. I'd also try out a quick google search of what your line of work is, to see what the industry standard is at that point in time.I wouldn't price too low, because you want to make your time worth it. You also want them to feel like they're paying for quality work (assuming you can deliver it :) ). Finally, think about your client. If it's a small business, then don't price it too high if you want the job. If it's an enterprise (like a Fortune company), then don't be afraid to price higher. They have the budget for it.Fixed price: If they want a fixed price project, then you need to think about how many hours it will take you to complete it and multiply it by the hourly rate you set for yourself. Then, honestly, I would add 10-20% on top of that. Why? Because nothing ever works exactly how you want it to. There are lots of times that something "trivial" is way harder than it should be, or something that "should work" doesn't for hours and it eats away at your hourly rate. I can't count the number of times I encountered a logical bug that took away an entire's day work because debuggers don't help in those cases. By adding that padding in, it's still OK to have those days where you don't get as much done as you want. And another useful tip: Depending on your client, and the scope, you most likely want to set that you both sign off on a specification sheet before doing any work, and that any changes will result in a re-evaulation of the price. This is to help protect you from being handed a huge new addition to the project half-way in, without any extra payment.Scope of project: Finally, is it a huge project? Is it really small/fast? This affects how much your client will be willing to pay. If it sounds big, they will be willing to pay more for it. If it seems really small, then you won't be able to get away with a large asking price (as easily).Ok, I priced it, now what?So now that you have the price, you want to make sure it feels justified to your client. I never set a price before I can really think about everything. For example, if you're still in your introduction phase, and they want a price, don't give one! Just comment that you will send them a proposal sheet with all the features outlined, and a price for everything. You don't want to shout out a low number and then deliver something that is way higher. You also don't want to shock them with a big number before they feel like they are getting a great product.Make up a proposal document in a word editor. Personally, I leave the price till the very end. Why? Because by the time they reach the end, you've already discussed all the great features you plan to implement, and how it's the best product they'll ever use, etc etc...so your price comes off as a steal! If you hit them up front with a price, they will read through the document with a negative bias. Think about those commercials on TV. They always go on about their product, then at the end, ask "What would you pay for something like this? $100? $50? How about $20!!". This is not by accident.Scenario: I finished the job way earlier than expectedYou have two options then. You can either polish the hell out of the application, and even throw in a few bonus features (assuming they are in-line with the customer's needs) or you can sit and wait on it until you near your deadline. Why don't you want to turn it in too early? Because you should treat that extra time as a surplus. If you said it is going to take you 3 weeks, and it took you only 1, you have a surplus of 2 weeks. I personally don't want to let them know that I can do a 3 week project in 1 week. Why not? Because that may not always be the case! I may later have a 3 week project that takes all 3 weeks, but if I set a precedent of delivering super early, then the pressure is on for that longer project. It also makes it harder to quote longer times if you keep delivering too early.Feel free to deliver early, but again, don't do it too early. They may also wonder why they paid you for 3 weeks of work if you're done in 1. They may further wonder if the product sucks, or what is wrong with it, if it's done so early, etc.I would just polish the application. Everyone loves polish in their applications. The smallest details are what make an application go from "functional" to "fantastic". And since you are still delivering on time, then they are still going to be very happy with you.Scenario: It's taking way too long to finish this, and the deadline is nearing/here!So this is not a fun scenario to be in, but it'll happen. Sometimes the scope of the project gets out of hand. The best policy here is OPENNESS/HONESTY. Tell them that the project is taking longer than expected, and give a reasonable time for when you think you'll have it done. I typically explain it in a way that makes it sound like it isn't something that I did wrong, but it's just something about the nature of the project. This really goes for any scenario, to be honest. Just continue to stay open and communicative about your progress. This doesn't mean that you should email them every five minutes (unless they want you to), but it does mean that maybe every few days or once a week, give them an update on where you're at, and what's next. They'll be happy to know they are paying for progress, and it'll make it easier to ask for an extension when something goes wrong, because they know that you've been working on it all along.Final tips and thoughts:In general, contract work is really fun and rewarding. It's nice to learn new things all the time, as mandated by the project ,and to challenge yourself to do things you may not have done before. The key is to build a great relationship with your clients for future work, and for recommendations. I am always very honest with them and I never promise something I can't deliver. Again, under promise, over deliver!I hope this has proved helpful!Cheers,samerpaul

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  • IE6 iframe anchor links moves iframe up

    - by WastedSpace
    Hi, Having a real head scratching moment... I have a site where there is a footer div that always sits at the bottom of the screen (26px high), and above that I have an iFrame which sizes to 100% of the remaining height. This works well. Even clicking on anchor links inside the iframe works as it should in all browsers (apart from IE6). Unfortunately I still have to support IE6. What is happening in IE6 is that the footer jumps up the page with the iframe still above it when I click on an anchor link. The top part of the iframe is cut off. Even the iframe's scroll bars disappear under the top of the browser. I have created some screen shots to show you what I mean. I have blurred out the actual data for now. How it should look (and does look) in other browsers: http://img100.imageshack.us/i/screen1om.jpg/ How it looks in IE6 before clicking on an anchor link: http://img532.imageshack.us/i/screen2e.jpg/ (I had to make the iframe's height 95%, because if I set it to 100% height weirdly it wouldn't show anything...) How it looks in IE6 after clicking on an anchor link: http://img214.imageshack.us/i/screen3g.jpg/ It's hard for me to show the fool code I am using, as there are lots of other things going on (of which I'm confident doesn't affect the layout), so will try to summarise: The html code (simplified): <div id="ifra"><iframe src="home.php" frameborder="0" name="content_pane" id="content_pane" marginheight="10" marginwidth="10"></iframe></div> <h1 class="toolbar"><a id="footerlink">Site Name</a></h1> The CSS (simplified): html, body { overflow: hidden; } html, body, iframe { height: 100%; } body { padding: 0; margin: 0; } #ifra, iframe { position: absolute; width: 100%; left: 0; } #ifra { top: 0px; bottom: 26px; } iframe { border: 0 none; } .toolbar { height: 26px; background-color: #C2C7C9; position: fixed; bottom: 0; width: 100%; background-image: url(bg.png); background-repeat: repeat-x; background-position: left top; } IE8 specific CSS: #ifra, .toolbar { position: fixed; } IE7 specific CSS: html { padding: 0px; } #ifra, iframe { position: absolute; } #ifra { top: 0px; bottom: 26px; } * html body { padding /**/: 100px 0 50px 0; overflow-y /**/: hidden; } IE6 specific CSS: .toolbar { position: fixed; } * html { overflow-y: hidden; } * html body { overflow-y: auto; height: 100%; } * html .toolbar { position: absolute; } iframe { height: 95%; } #ifra { height: 100%; } I know it's not ideal not seeing the full code, but just wondering if there is anything jumping out at anyone from these lines of code? By the way I did consider dropping the div surrounding the iframe, but for some reason the scroll bars would disappear under the footer in all browsers... Thanks for looking! Ali.

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  • Can someone code review my small SDL app? Want to make sure I didn't make any beginner mistakes

    - by SDLFunTimes
    In an effort to teach myself the SDL library (hence my stack overflow handle :) ) I wanted to try my hand at a side-scroller. My code is complete but I want some feedback (mostly because I have an atrocious amount of if and else statements for what seems like some simple logic). My "program" is a c++ side-scroller where you move a single sprite across the screen. No jumping, bad guys, guns, scores, levels or anything. I wanted to use this as a base to build up upon. So I figured if my base is wrong I could end up with some pretty bad future apps. It's also multi-threaded. Next up on this I would like to make the person sprite animated (so it looks like he's walking rather than sliding) as well as make the person go faster when the arrow buttons are held down longer). The code is kind of long but here's my main method. There's a link at the bottom for the whole program: #include <iostream> #include "SDL.h" #include "game.hpp" using std::cout; using std::endl; const int SCREENW = 200; const int SCREENH = 200; const int BPP = 32; const int FPS = 24; int event_loop(void* stuff); int display_loop(void* stuff); int main(int argc, char** argv) { SDL_Init(SDL_INIT_EVERYTHING | SDL_INIT_EVENTTHREAD); SDL_Thread* events_thurd; SDL_Thread* display_thurd; SDL_Surface* screen = SDL_SetVideoMode(SCREENW, SCREENH, BPP, SDL_SWSURFACE); SDL_EnableKeyRepeat(SDL_DEFAULT_REPEAT_DELAY, SDL_DEFAULT_REPEAT_INTERVAL); SDL_Event event; Game* thug_aim = new Game(&event, screen, SCREENW, SCREENH, BPP); events_thurd = SDL_CreateThread(event_loop, (void*)thug_aim); display_thurd = SDL_CreateThread(display_loop, (void*)thug_aim); SDL_WaitThread(events_thurd, NULL); SDL_KillThread(display_thurd); delete thug_aim; return 0; } int event_loop(void* stuff) { Game* gamez = (Game*)stuff; SDL_Event* event = gamez->get_event(); while(1) { while(SDL_PollEvent(event)) { if(event->type == SDL_QUIT) { return 0; } else if(event->type == SDL_KEYDOWN) { if(event->key.keysym.sym == SDLK_LEFT || event->key.keysym.sym == SDLK_RIGHT) { gamez->move(event->key.keysym.sym); } } else if(event->type == SDL_KEYUP) { if(event->key.keysym.sym == SDLK_LEFT || event->key.keysym.sym == SDLK_RIGHT) { gamez->stop_move(event->key.keysym.sym); } } else { //not an event that concerns this game } } } } int display_loop(void* stuff) { Game* gamez = (Game*)stuff; double period = 1 / FPS * 1000; Uint32 milli_period = (Uint32)period; //get some of the attributes from gamez SDL_Rect* background_rect = gamez->get_background_rect(); SDL_Rect* person_rect = gamez->get_person_rect(); SDL_Surface* screen = gamez->get_screen(); SDL_Surface* background = gamez->get_background(); SDL_Surface* person = gamez->get_person(); Uint32 start, end; int sleep; while(1) { start = SDL_GetTicks(); //blit background SDL_BlitSurface(background, background_rect, screen, NULL); //blit person SDL_BlitSurface(person, NULL, screen, person_rect); end = SDL_GetTicks(); sleep = milli_period - (end - start); if(sleep < 0) { sleep = 0; } SDL_Delay((Uint32)sleep); if(SDL_Flip(gamez->get_screen()) != 0) { cout << "error drawing to screen: " << SDL_GetError() << endl; } } } Here's the link to the .zip file of all my code (please ignore some of the variable names ;-) ): Anyway can you guys take a look and tell me what you think? url edit: holy crap I didn't know 2shared was such a shitty site. Looking for a better uploader than that or rapidshare / mediafire.

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  • Calculus? Need help solving for a time-dependent variable given some other variables.

    - by user451527
    Long story short, I'm making a platform game. I'm not old enough to have taken Calculus yet, so I know not of derivatives or integrals, but I know of them. The desired behavior is for my character to automagically jump when there is a block to either side of him that is above the one he's standing on; for instance, stairs. This way the player can just hold left / right to climb stairs, instead of having to spam the jump key too. The issue is with the way I've implemented jumping; I've decided to go mario-style, and allow the player to hold 'jump' longer to jump higher. To do so, I have a 'jump' variable which is added to the player's Y velocity. The jump variable increases to a set value when the 'jump' key is pressed, and decreases very quickly once the 'jump' key is released, but decreases less quickly so long as you hold the 'jump' key down, thus providing continuous acceleration up as long as you hold 'jump.' This also makes for a nice, flowing jump, rather than a visually jarring, abrupt acceleration. So, in order to account for variable stair height, I want to be able to calculate exactly what value the 'jump' variable should get in order to jump exactly to the height of the stair; preferably no more, no less, though slightly more is permissible. This way the character can jump up steep or shallow flights of stairs without it looking weird or being slow. There are essentially 5 variables in play: h -the height the character needs to jump to reach the stair top<br> j -the jump acceleration variable<br> v -the vertical velocity of the character<br> p -the vertical position of the character<br> d -initial vertical position of the player minus final position<br> Each timestep:<br> j -= 1.5; //the jump variable's deceleration<br> v -= j; //the jump value's influence on vertical speed<br> v *= 0.95; //friction on the vertical speed<br> v += 1; //gravity<br> p += v; //add the vertical speed to the vertical position<br> v-initial is known to be zero<br> v-final is known to be zero<br> p-initial is known<br> p-final is known<br> d is known to be p-initial minus p-final<br> j-final is known to be zero<br> j-initial is unknown<br> Given all of these facts, how can I make an equation that will solve for j? tl;dr How do I Calculus? Much thanks to anyone who's made it this far and decides to plow through this problem.

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  • Java multiple class compositing and boiler plate reduction

    - by h2g2java
    We all know why Java does/should not have multiple inheritance. So this is not questioning about what has already been debated till-cows-come-home. This discusses what we would do when we wish to create a class that has the characteristics of two or more other classes. Probably, most of us would do this to "inherit" from three classes. For simplicity, I left out the constructor.: class Car extends Vehicle { final public Transport transport; final public Machine machine; } So that, Car class directly inherits methods and objects of Vehicle class, but would have to refer to transport and machine explicitly to refer to objects instantiated in Transport and Machine. Car car = new Car(); car.drive(); // from Vehicle car.transport.isAmphibious(); // from Transport car.machine.getCO2Footprint(); // from Machine I thought this was a good idea until when I encounter frameworks that require setter and getter methods. For example, the XML <Car amphibious='false' footPrint='1000' model='Fordstatic999'/> would look for the methods setAmphibious(..), setFootPrint(..) and setModel(..). Therefore, I have to project the methods from Transport and Machine classes class Car extends Vehicle { final public Transport transport; final public Machine machine; public void setAmphibious(boolean b){ this.transport.setAmphibious(b); } public void setFootPrint(String fp){ this.machine.setFootPrint(fp); } } This is OK, if there were just a few characteristics. Right now, I am trying to adapt all of SmartGWT into GWT UIBinder, especially those classes that are not a GWT widget. There are lots of characteristics to project. Wouldn't it be nice if there exists some form of annotation framework that is like this: class Car extends Vehicle @projects {Transport @projects{Machine @projects Guzzler}} { /* No need to explicitly instantiate Transport, Machine or Guzzler */ .... } Where, in case of common names of characteristics exist, the characteristics of Machine would take precedence Guzzler's, and Transport's would have precedence over Machine's, and Vehicle's would have precedence over Transport's. The annotation framework would then instantiate Transport, Machine and Guzzler as hidden members of Car and expand to break-out the protected/public characteristics, in the precedence dictated by the @project annotation sequence, into actual source code or into byte-code. Preferably into byte-code. So that the setFootPrint method is found in both Machine and Guzzler, only that of Machine's would be projected. Questions: Don't you think this is a good idea to have such a framework? Does such a framework already exist? Tell me where/what. Is there an eclipse plugin that does it? Is there a proposal or plan anywhere that you know about such an annotation framework? It would be wonderful too, if the annotation/plugin framework lets me specify that boolean, int, or whatever else needs to be converted from String and does the conversion/parsing for me too. Please advise, somebody. I hope wording of my question was clear enough. Thx. Edited: To avoid OO enthusiasts jumping to conclusion, I have renamed the title of this question.

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  • Change ListView background - strage behaviour

    - by Beasly
    Hi again, I have a problem with changing the background of a view in a ListView. What I need: Change the background image of a row onClick() What actually happens: The background gets changed (selected) after pressing e.g. the first entry. But after scrolling down the 8th entry is selected too. Scroll back to the top the first isn't selected anymore. The second entry is selected now. Continue scrolling and it continues jumping... What i'm dong in the Code: I have channels, and onClick() I toggle an attribute of channel boolean selected and then I change the background. I'm doing this only onClick() thats why I don't get why it's actuelly happening on other entries too. One thing I notices is: It seems to be only the "drawing"-part because the item which get selected "by it self" has still the selected value on false I think it seems to have something to do with the reuse of the views in the custom ListAdapters getView(...) Code of onClick() in ListActivity: @Override protected ViewHolder createHolder(View v) { // createHolder will be called only as long, as the ListView is not // filled TextView title = (TextView) v .findViewById(R.id.tv_title_channel_list_adapter); TextView content = (TextView) v .findViewById(R.id.tv_content_channel_list_adapter); ImageView icon = (ImageView) v .findViewById(R.id.icon_channel_list_adapter); if (title == null || content == null || icon == null) { Log.e("ERROR on findViewById", "Couldn't find Title, Content or Icon"); } ViewHolder mvh = new MyViewHolder(title, content, icon); // We make the views become clickable // so, it is not necessary to use the android:clickable attribute in // XML v.setOnClickListener(new ChannelListAdapter.OnClickListener(mvh) { public void onClick(View v, ViewHolder viewHolder) { // we toggle the enabled state and also switch the the // background MyViewHolder mvh = (MyViewHolder) viewHolder; Channel ch = (Channel) mvh.data; ch.setSelected(!ch.getSelected()); // toggle if (ch.getSelected()) { v.setBackgroundResource(R.drawable.row_blue_selected); } else { v.setBackgroundResource(R.drawable.row_blue); } // TESTING Log.d("onClick() Channel", "onClick() Channel: " + ch.getTitle() + " selected: " + ch.getSelected()); } }); return mvh; } Code of getView(...): @Override public View getView(int position, View view, ViewGroup parent) { ViewHolder holder; // When view is not null, we can reuse it directly, there is no need // to reinflate it. // We only inflate a new View when the view supplied by ListView is // null. if (view == null) { view = mInflater.inflate(mViewId, null); // call own implementation holder = createHolder(view); // TEST // we set the holder as tag view.setTag(holder); } else { // get holder back...much faster than inflate holder = (ViewHolder) view.getTag(); } // we must update the object's reference holder.data = getItem(position); // call the own implementation bindHolder(holder); return view; } I really would appreciate any idea how to solve this! :) If more information is needed please tell me. Thanks in advance!

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  • I'm looking for a reliable way to verify T-SQL stored procedures. Anybody got one?

    - by Cory Larson
    Hi all-- We're upgrading from SQL Server 2005 to 2008. Almost every database in the 2005 instance is set to 2000 compatibility mode, but we're jumping to 2008. Our testing is complete, but what we've learned is that we need to get faster at it. I've discovered some stored procedures that either SELECT data from missing tables or try to ORDER BY columns that don't exist. Wrapping the SQL to create the procedures in SET PARSEONLY ON and trapping errors in a try/catch only catches the invalid columns in the ORDER BYs. It does not find the error with the procedure selecting data from the missing table. SSMS 2008's intellisense, however, DOES find the issue, but I can still go ahead and successfully run the ALTER script for the procedure without it complaining. So, why can I even get away with creating a procedure that fails when it runs? Are there any tools out there that can do better than what I've tried? The first tool I found wasn't very useful: DbValidator from CodeProject, but it finds fewer problems than this script I found on SqlServerCentral, which found the invalid column references. ------------------------------------------------------------------------- -- Check Syntax of Database Objects -- Copyrighted work. Free to use as a tool to check your own code or in -- any software not sold. All other uses require written permission. ------------------------------------------------------------------------- -- Turn on ParseOnly so that we don't actually execute anything. SET PARSEONLY ON GO -- Create a table to iterate through declare @ObjectList table (ID_NUM int NOT NULL IDENTITY (1, 1), OBJ_NAME varchar(255), OBJ_TYPE char(2)) -- Get a list of most of the scriptable objects in the DB. insert into @ObjectList (OBJ_NAME, OBJ_TYPE) SELECT name, type FROM sysobjects WHERE type in ('P', 'FN', 'IF', 'TF', 'TR', 'V') order by type, name -- Var to hold the SQL that we will be syntax checking declare @SQLToCheckSyntaxFor varchar(max) -- Var to hold the name of the object we are currently checking declare @ObjectName varchar(255) -- Var to hold the type of the object we are currently checking declare @ObjectType char(2) -- Var to indicate our current location in iterating through the list of objects declare @IDNum int -- Var to indicate the max number of objects we need to iterate through declare @MaxIDNum int -- Set the inital value and max value select @IDNum = Min(ID_NUM), @MaxIDNum = Max(ID_NUM) from @ObjectList -- Begin iteration while @IDNum <= @MaxIDNum begin -- Load per iteration values here select @ObjectName = OBJ_NAME, @ObjectType = OBJ_TYPE from @ObjectList where ID_NUM = @IDNum -- Get the text of the db Object (ie create script for the sproc) SELECT @SQLToCheckSyntaxFor = OBJECT_DEFINITION(OBJECT_ID(@ObjectName, @ObjectType)) begin try -- Run the create script (remember that PARSEONLY has been turned on) EXECUTE(@SQLToCheckSyntaxFor) end try begin catch -- See if the object name is the same in the script and the catalog (kind of a special error) if (ERROR_PROCEDURE() <> @ObjectName) begin print 'Error in ' + @ObjectName print ' The Name in the script is ' + ERROR_PROCEDURE()+ '. (They don''t match)' end -- If the error is just that this already exists then we don't want to report that. else if (ERROR_MESSAGE() <> 'There is already an object named ''' + ERROR_PROCEDURE() + ''' in the database.') begin -- Report the error that we got. print 'Error in ' + ERROR_PROCEDURE() print ' ERROR TEXT: ' + ERROR_MESSAGE() end end catch -- Setup to iterate to the next item in the table select @IDNum = case when Min(ID_NUM) is NULL then @IDNum + 1 else Min(ID_NUM) end from @ObjectList where ID_NUM > @IDNum end -- Turn the ParseOnly back off. SET PARSEONLY OFF GO Any suggestions?

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  • iPhone multi-touch move, scale and rotate, how to prevent scale?

    - by russhill
    I have existing code for tracking multi-touch positions and then moving, rotating and scaling the item - in this case an image - appropriately. The code works really well and in itself is perfect, however for this particular task, I need the movement and rotation ONLY. I have spent time trying to work out what is going on in this routine, but maths is not my strong point so wanted to see if anyone could assist? - (CGAffineTransform)incrementalTransformWithTouches:(NSSet *)touches { NSArray *sortedTouches = [[touches allObjects] sortedArrayUsingSelector:@selector(compareAddress:)]; NSInteger numTouches = [sortedTouches count]; // No touches if (numTouches == 0) { return CGAffineTransformIdentity; } // Single touch if (numTouches == 1) { UITouch *touch = [sortedTouches objectAtIndex:0]; CGPoint beginPoint = *(CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch); CGPoint currentPoint = [touch locationInView:self.superview]; return CGAffineTransformMakeTranslation(currentPoint.x - beginPoint.x, currentPoint.y - beginPoint.y); } // If two or more touches, go with the first two (sorted by address) UITouch *touch1 = [sortedTouches objectAtIndex:0]; UITouch *touch2 = [sortedTouches objectAtIndex:1]; CGPoint beginPoint1 = *(CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch1); CGPoint currentPoint1 = [touch1 locationInView:self.superview]; CGPoint beginPoint2 = *(CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch2); CGPoint currentPoint2 = [touch2 locationInView:self.superview]; double layerX = self.center.x; double layerY = self.center.y; double x1 = beginPoint1.x - layerX; double y1 = beginPoint1.y - layerY; double x2 = beginPoint2.x - layerX; double y2 = beginPoint2.y - layerY; double x3 = currentPoint1.x - layerX; double y3 = currentPoint1.y - layerY; double x4 = currentPoint2.x - layerX; double y4 = currentPoint2.y - layerY; // Solve the system: // [a b t1, -b a t2, 0 0 1] * [x1, y1, 1] = [x3, y3, 1] // [a b t1, -b a t2, 0 0 1] * [x2, y2, 1] = [x4, y4, 1] double D = (y1-y2)*(y1-y2) + (x1-x2)*(x1-x2); if (D < 0.1) { return CGAffineTransformMakeTranslation(x3-x1, y3-y1); } double a = (y1-y2)*(y3-y4) + (x1-x2)*(x3-x4); double b = (y1-y2)*(x3-x4) - (x1-x2)*(y3-y4); double tx = (y1*x2 - x1*y2)*(y4-y3) - (x1*x2 + y1*y2)*(x3+x4) + x3*(y2*y2 + x2*x2) + x4*(y1*y1 + x1*x1); double ty = (x1*x2 + y1*y2)*(-y4-y3) + (y1*x2 - x1*y2)*(x3-x4) + y3*(y2*y2 + x2*x2) + y4*(y1*y1 + x1*x1); return CGAffineTransformMake(a/D, -b/D, b/D, a/D, tx/D, ty/D); } I have tried to read up on the way matrix's work, but cannot figure it out entirely. More likely to be the issue is the calculations, which as I mention is not my strong point. What I need from this routine is a transform that performs my movement and rotation but ignores scale - so the distance between the 2 finger touch points is ignored and scale is not affected. I have looked at other routines on the internet to handle multi-touch rotation but all the ones I tried had issues in some way or other (smoothness, jumping when lifting fingers etc), whereas the above code is spot on for move, scale and rotate actions. Any help appreciated!

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  • ActionScript MovieClip moves to the left, but not the right

    - by Defcon
    I have a stage with a movie clip with the instance name of "mc". Currently I have a code that is suppose to move the player left and right, and when the left or right key is released, the "mc" slides a little bit. The problem I'm having is that making the "mc" move to the left works, but the exact some code used for the right doesn't. All of this code is present on the Main Stage - Frame One //Variables var mcSpeed:Number = 0;//MC's Current Speed var mcJumping:Boolean = false;//if mc is Jumping var mcFalling:Boolean = false;//if mc is Falling var mcMoving:Boolean = false;//if mc is Moving var mcSliding:Boolean = false;//if mc is sliding var mcSlide:Number = 0;//Stored for use when creating slide var mcMaxSlide:Number = 1.6;//Max Distance the object will slide. //Player Move Function p1Move = new Object(); p1Move = function (dir:String, maxSpeed:Number) { if (dir == "left" && _root.mcSpeed<maxSpeed) { _root.mcSpeed += .2; _root.mc._x -= _root.mcSpeed; } else if (dir == "right" && _root.mcSpeed<maxSpeed) { _root.mcSpeed += .2; _root.mc._x += _root.mcSpeed; } else if (dir == "left" && speed>=maxSpeed) { _root.mc._x -= _root.mcSpeed; } else if (dir == "right" && _root.mcSpeed>=maxSpeed) { _root.mc._x += _root.mcSpeed; } } //onEnterFrame for MC mc.onEnterFrame = function():Void { if (Key.isDown(Key.LEFT)) { if (_root.mcMoving == false && _root.mcSliding == false) { _root.mcMoving = true; } else if (_root.mcMoving == true && _root.mcSliding == false) { _root.p1Move("left",5); } } else if (!Key.isDown(Key.LEFT)) { if (_root.mcMoving == true && _root.mcSliding == false) { _root.mcSliding = true; } else if (_root.mcMoving == true && _root.mcSliding == true && _root.mcSlide<_root.mcMaxSlide) { _root.mcSlide += .2; this._x -= .2; } else if (_root.mcMoving == true && _root.mcSliding == true && _root.mcSlide>=_root.mcMaxSlide) { _root.mcMoving = false; _root.mcSliding = false; _root.mcSlide = 0; _root.mcSpeed = 0; } } else if (Key.isDown(Key.RIGHT)) { if (_root.mcMoving == false && _root.mcSliding == false) { _root.mcMoving = true; } else if (_root.mcMoving == true && _root.mcSliding == false) { _root.p1Move("right",5); } } else if (!Key.isDown(Key.RIGHT)) { if (_root.mcMoving == true && _root.mcSliding == false) { _root.mcSliding = true; } else if (_root.mcMoving == true && _root.mcSliding == true && _root.mcSlide<_root.mcMaxSpeed) { _root.mcSlide += .2; this._x += .2; } else if (_root.mcMoving == true && _root.mcSliding == true && _root.mcSlide>=_root.mcMax) { _root.mcMoving = false; _root.mcSliding = false; _root.mcSlide = 0; _root.mcSpeed = 0; } } }; I just don't get why when you press the left arrow its works completely fine, but when you press the right arrow it doesn't respond. It is literally the same code.

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  • Running game, leaving game and continuing animation

    - by Madrusec
    I have been trying to learn some Actionscript recently and have been trying to run an interactive story that at one point turns into an extremel simple shooter game. After the player either wins or looses, then he/she is taken to the rest of the animated story. So I have everything up to the point where the games runs (successfully) but for some reason I am unable to have flash run the rest of the frames, most of which have no code at all. This is the code for scene 1: stop (); import flash.display.MovieClip; import flash.events.MouseEvent; import flash.utils.Timer; import flash.events.TimerEvent; var stoneInGame:uint; var stoneMaker: Timer; var container_mc: MovieClip; var cursor:MovieClip; var score:int; var anxiety:int; var anxiety_mc :MovieClip = new mcAnxiety(); //stage.addChild( anxiety_mc ); function initializeGame():void { stoneInGame = 10; stoneMaker = new Timer(1000, stoneInGame); container_mc = new MovieClip(); addChild(container_mc); container_mc.addChild(anxiety_mc); anxiety_mc.x = 497; anxiety_mc.y = 360; stoneMaker.addEventListener(TimerEvent.TIMER, createStones); stoneMaker.start(); cursor = new Cursor(); addChild(cursor); cursor.enabled = false; Mouse.hide(); stage.addEventListener(MouseEvent.MOUSE_MOVE, dragCursor); score = 0; anxiety = anxiety_mc.totalFrames; anxiety_mc.gotoAndStop(anxiety); } function dragCursor(event:MouseEvent):void { cursor.x = this.mouseX; cursor.y = this.mouseY; } function createStones(event:TimerEvent):void { var stone:MovieClip; stone = new Stone(); stone.x = Math.random() * stage.stageWidth; stone.y = Math.random() * stage.stageHeight; container_mc.addChild(stone); } function increaseScore():void { score ++; if(score >= stoneInGame) { dragCursor.stop(); createStones.stop(); stoneMaker.stop(); trace("you wind!"); } } function decreaseAnxiety():void { anxiety--; if(anxiety <= 0) { stoneMaker.stop(); trace("you lose!"); } else { anxiety_mc.gotoAndStop(anxiety); } increaseScore(); } initializeGame(); So what I tried to do was adding gotoAndPlay() inside both the decreaseAnxiety and increaseScore functions after the trace statements and referenced a frame where I have more keyframes that continue a story. However, Flash just goes back to the beginning of the timeline and I even the functions that change and control the cursor seem to be running. This leads me to believe that I need to make sure that I tell flash o stup running certain functions before jumping to another frame. However, it seems to me that I would still have the same issue and not be able to continue in the timeline. Is there something I am missing? How can I jump out of all this code once the game finishes and simply continue playing the rest of the frames? Any pointers would be greatly appreciated. Thank you

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  • How to reduce iOS AVPlayer start delay

    - by Bernt Habermeier
    Note, for the below question: All assets are local on the device -- no network streaming is taking place. The videos contain audio tracks. I'm working on an iOS application that requires playing video files with minimum delay to start the video clip in question. Unfortunately we do not know what specific video clip is next until we actually need to start it up. Specifically: When one video clip is playing, we will know what the next set of (roughly) 10 video clips are, but we don't know which one exactly, until it comes time to 'immediately' play the next clip. What I've done to look at actual start delays is to call addBoundaryTimeObserverForTimes on the video player, with a time period of one millisecond to see when the video actually started to play, and I take the difference of that time stamp with the first place in the code that indicates which asset to start playing. From what I've seen thus-far, I have found that using the combination of AVAsset loading, and then creating an AVPlayerItem from that once it's ready, and then waiting for AVPlayerStatusReadyToPlay before I call play, tends to take between 1 and 3 seconds to start the clip. I've since switched to what I think is roughly equivalent: calling [AVPlayerItem playerItemWithURL:] and waiting for AVPlayerItemStatusReadyToPlay to play. Roughly same performance. One thing I'm observing is that the first AVPlayer item load is slower than the rest. Seems one idea is to pre-flight the AVPlayer with a short / empty asset before trying to play the first video might be of good general practice. [http://stackoverflow.com/questions/900461/slow-start-for-avaudioplayer-the-first-time-a-sound-is-played] I'd love to get the video start times down as much as possible, and have some ideas of things to experiment with, but would like some guidance from anyone that might be able to help. Update: idea 7, below, as-implemented yields switching times of around 500 ms. This is an improvement, but it it'd be nice to get this even faster. Idea 1: Use N AVPlayers (won't work) Using ~ 10 AVPPlayer objects and start-and-pause all ~ 10 clips, and once we know which one we really need, switch to, and un-pause the correct AVPlayer, and start all over again for the next cycle. I don't think this works, because I've read there is roughly a limit of 4 active AVPlayer's in iOS. There was someone asking about this on StackOverflow here, and found out about the 4 AVPlayer limit: fast-switching-between-videos-using-avfoundation Idea 2: Use AVQueuePlayer (won't work) I don't believe that shoving 10 AVPlayerItems into an AVQueuePlayer would pre-load them all for seamless start. AVQueuePlayer is a queue, and I think it really only makes the next video in the queue ready for immediate playback. I don't know which one out of ~10 videos we do want to play back, until it's time to start that one. ios-avplayer-video-preloading Idea 3: Load, Play, and retain AVPlayerItems in background (not 100% sure yet -- but not looking good) I'm looking at if there is any benefit to load and play the first second of each video clip in the background (suppress video and audio output), and keep a reference to each AVPlayerItem, and when we know which item needs to be played for real, swap that one in, and swap the background AVPlayer with the active one. Rinse and Repeat. The theory would be that recently played AVPlayer/AVPlayerItem's may still hold some prepared resources which would make subsequent playback faster. So far, I have not seen benefits from this, but I might not have the AVPlayerLayer setup correctly for the background. I doubt this will really improve things from what I've seen. Idea 4: Use a different file format -- maybe one that is faster to load? I'm currently using .m4v's (video-MPEG4) H.264 format. I have not played around with other formats, but it may well be that some formats are faster to decode / get ready than others. Possible still using video-MPEG4 but with a different codec, or maybe quicktime? Maybe a lossless video format where decoding / setup is faster? Idea 5: Combination of lossless video format + AVQueuePlayer If there is a video format that is fast to load, but maybe where the file size is insane, one idea might be to pre-prepare the first 10 seconds of each video clip with a version that is boated but faster to load, but back that up with an asset that is encoded in H.264. Use an AVQueuePlayer, and add the first 10 seconds in the uncompressed file format, and follow that up with one that is in H.264 which gets up to 10 seconds of prepare/preload time. So I'd get 'the best' of both worlds: fast start times, but also benefits from a more compact format. Idea 6: Use a non-standard AVPlayer / write my own / use someone else's Given my needs, maybe I can't use AVPlayer, but have to resort to AVAssetReader, and decode the first few seconds (possibly write raw file to disk), and when it comes to playback, make use of the raw format to play it back fast. Seems like a huge project to me, and if I go about it in a naive way, it's unclear / unlikely to even work better. Each decoded and uncompressed video frame is 2.25 MB. Naively speaking -- if we go with ~ 30 fps for the video, I'd end up with ~60 MB/s read-from-disk requirement, which is probably impossible / pushing it. Obviously we'd have to do some level of image compression (perhaps native openGL/es compression formats via PVRTC)... but that's kind crazy. Maybe there is a library out there that I can use? Idea 7: Combine everything into a single movie asset, and seekToTime One idea that might be easier than some of the above, is to combine everything into a single movie, and use seekToTime. The thing is that we'd be jumping all around the place. Essentially random access into the movie. I think this may actually work out okay: avplayer-movie-playing-lag-in-ios5 Which approach do you think would be best? So far, I've not made that much progress in terms of reducing the lag.

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  • Metro Walkthrough: Creating a Task List with a ListView and IndexedDB

    - by Stephen.Walther
    The goal of this blog entry is to describe how you can work with data in a Metro style application written with JavaScript. In particular, we create a super simple Task List application which enables you to create and delete tasks. Here’s a video which demonstrates how the Task List application works: In order to build this application, I had to take advantage of several features of the WinJS library and technologies including: IndexedDB – The Task List application stores data in an IndexedDB database. HTML5 Form Validation – The Task List application uses HTML5 validation to ensure that a required field has a value. ListView Control – The Task List application displays the tasks retrieved from the IndexedDB database in a WinJS ListView control. Creating the IndexedDB Database The Task List application stores all of its data in an IndexedDB database named TasksDB. This database is opened/created with the following code: var db; var req = window.msIndexedDB.open("TasksDB", 1); req.onerror = function () { console.log("Could not open database"); }; req.onupgradeneeded = function (evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement:true }); }; The msIndexedDB.open() method accepts two parameters: the name of the database to open and the version of the database to open. If a database with a matching version already exists, then calling the msIndexedDB.open() method opens a connection to the existing database. If the database does not exist then the upgradeneeded event is raised. You handle the upgradeneeded event to create a new database. In the code above, the upgradeneeded event handler creates an object store named “tasks” (An object store roughly corresponds to a database table). When you add items to the tasks object store then each item gets an id property with an auto-incremented value automatically. The code above also includes an error event handler. If the IndexedDB database cannot be opened or created, for whatever reason, then an error message is written to the Visual Studio JavaScript Console window. Displaying a List of Tasks The TaskList application retrieves its list of tasks from the tasks object store, which we created above, and displays the list of tasks in a ListView control. Here is how the ListView control is declared: <div id="tasksListView" data-win-control="WinJS.UI.ListView" data-win-options="{ itemDataSource: TaskList.tasks.dataSource, itemTemplate: select('#taskTemplate'), tapBehavior: 'toggleSelect', selectionMode: 'multi', layout: { type: WinJS.UI.ListLayout } }"> </div> The ListView control is bound to the TaskList.tasks.dataSource data source. The TaskList.tasks.dataSource is created with the following code: // Create the data source var tasks = new WinJS.Binding.List(); // Open the database var db; var req = window.msIndexedDB.open("TasksDB", 1); req.onerror = function () { console.log("Could not open database"); }; req.onupgradeneeded = function (evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement:true }); }; // Load the data source with data from the database req.onsuccess = function () { db = req.result; var tran = db.transaction("tasks"); tran.objectStore("tasks").openCursor().onsuccess = function(event) { var cursor = event.target.result; if (cursor) { tasks.dataSource.insertAtEnd(null, cursor.value); cursor.continue(); }; }; }; // Expose the data source and functions WinJS.Namespace.define("TaskList", { tasks: tasks }); Notice the success event handler. This handler is called when a database is successfully opened/created. In the code above, all of the items from the tasks object store are retrieved into a cursor and added to a WinJS.Binding.List object named tasks. Because the ListView control is bound to the WinJS.Binding.List object, copying the tasks from the object store into the WinJS.Binding.List object causes the tasks to appear in the ListView: Adding a New Task You add a new task in the Task List application by entering the title of a new task into an HTML form and clicking the Add button. Here’s the markup for creating the form: <form id="addTaskForm"> <input id="newTaskTitle" title="New Task" required /> <button>Add</button> </form> Notice that the INPUT element includes a required attribute. In a Metro application, you can take advantage of HTML5 Validation to validate form fields. If you don’t enter a value for the newTaskTitle field then the following validation error message is displayed: For a brief introduction to HTML5 validation, see my previous blog entry: http://stephenwalther.com/blog/archive/2012/03/13/html5-form-validation.aspx When you click the Add button, the form is submitted and the form submit event is raised. The following code is executed in the default.js file: // Handle Add Task document.getElementById("addTaskForm").addEventListener("submit", function (evt) { evt.preventDefault(); var newTaskTitle = document.getElementById("newTaskTitle"); TaskList.addTask({ title: newTaskTitle.value }); newTaskTitle.value = ""; }); The code above retrieves the title of the new task and calls the addTask() method in the tasks.js file. Here’s the code for the addTask() method which is responsible for actually adding the new task to the IndexedDB database: // Add a new task function addTask(taskToAdd) { var transaction = db.transaction("tasks", "readwrite"); var addRequest = transaction.objectStore("tasks").add(taskToAdd); addRequest.onsuccess = function (evt) { taskToAdd.id = evt.target.result; tasks.dataSource.insertAtEnd(null, taskToAdd); } } The code above does two things. First, it adds the new task to the tasks object store in the IndexedDB database. Second, it adds the new task to the data source bound to the ListView. The dataSource.insertAtEnd() method is called to add the new task to the data source so the new task will appear in the ListView (with a nice little animation). Deleting Existing Tasks The Task List application enables you to select one or more tasks by clicking or tapping on one or more tasks in the ListView. When you click the Delete button, the selected tasks are removed from both the IndexedDB database and the ListView. For example, in the following screenshot, two tasks are selected. The selected tasks appear with a teal background and a checkmark: When you click the Delete button, the following code in the default.js file is executed: // Handle Delete Tasks document.getElementById("btnDeleteTasks").addEventListener("click", function (evt) { tasksListView.winControl.selection.getItems().then(function(items) { items.forEach(function (item) { TaskList.deleteTask(item); }); }); }); The selected tasks are retrieved with the TaskList selection.getItem() method. In the code above, the deleteTask() method is called for each of the selected tasks. Here’s the code for the deleteTask() method: // Delete an existing task function deleteTask(listViewItem) { // Database key != ListView key var dbKey = listViewItem.data.id; var listViewKey = listViewItem.key; // Remove item from db and, if success, remove item from ListView var transaction = db.transaction("tasks", “readwrite”); var deleteRequest = transaction.objectStore("tasks").delete(dbKey); deleteRequest.onsuccess = function () { tasks.dataSource.remove(listViewKey); } } This code does two things: it deletes the existing task from the database and removes the existing task from the ListView. In both cases, the right task is removed by using the key associated with the task. However, the task key is different in the case of the database and in the case of the ListView. In the case of the database, the task key is the value of the task id property. In the case of the ListView, on the other hand, the task key is auto-generated by the ListView. When the task is removed from the ListView, an animation is used to collapse the tasks which appear above and below the task which was removed. The Complete Code Above, I did a lot of jumping around between different files in the application and I left out sections of code. For the sake of completeness, I want to include the entire code here: the default.html, default.js, and tasks.js files. Here are the contents of the default.html file. This file contains the UI for the Task List application: <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Task List</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- TaskList references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> <script type="text/javascript" src="js/tasks.js"></script> <style type="text/css"> body { font-size: x-large; } form { display: inline; } #appContainer { margin: 20px; width: 600px; } .win-container { padding: 10px; } </style> </head> <body> <div> <!-- Templates --> <div id="taskTemplate" data-win-control="WinJS.Binding.Template"> <div> <span data-win-bind="innerText:title"></span> </div> </div> <h1>Super Task List</h1> <div id="appContainer"> <form id="addTaskForm"> <input id="newTaskTitle" title="New Task" required /> <button>Add</button> </form> <button id="btnDeleteTasks">Delete</button> <div id="tasksListView" data-win-control="WinJS.UI.ListView" data-win-options="{ itemDataSource: TaskList.tasks.dataSource, itemTemplate: select('#taskTemplate'), tapBehavior: 'toggleSelect', selectionMode: 'multi', layout: { type: WinJS.UI.ListLayout } }"> </div> </div> </div> </body> </html> Here is the code for the default.js file. This code wires up the Add Task form and Delete button: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { WinJS.UI.processAll().then(function () { // Get reference to Tasks ListView var tasksListView = document.getElementById("tasksListView"); // Handle Add Task document.getElementById("addTaskForm").addEventListener("submit", function (evt) { evt.preventDefault(); var newTaskTitle = document.getElementById("newTaskTitle"); TaskList.addTask({ title: newTaskTitle.value }); newTaskTitle.value = ""; }); // Handle Delete Tasks document.getElementById("btnDeleteTasks").addEventListener("click", function (evt) { tasksListView.winControl.selection.getItems().then(function(items) { items.forEach(function (item) { TaskList.deleteTask(item); }); }); }); }); } }; app.start(); })(); Finally, here is the tasks.js file. This file contains all of the code for opening, creating, and interacting with IndexedDB: (function () { "use strict"; // Create the data source var tasks = new WinJS.Binding.List(); // Open the database var db; var req = window.msIndexedDB.open("TasksDB", 1); req.onerror = function () { console.log("Could not open database"); }; req.onupgradeneeded = function (evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement:true }); }; // Load the data source with data from the database req.onsuccess = function () { db = req.result; var tran = db.transaction("tasks"); tran.objectStore("tasks").openCursor().onsuccess = function(event) { var cursor = event.target.result; if (cursor) { tasks.dataSource.insertAtEnd(null, cursor.value); cursor.continue(); }; }; }; // Add a new task function addTask(taskToAdd) { var transaction = db.transaction("tasks", "readwrite"); var addRequest = transaction.objectStore("tasks").add(taskToAdd); addRequest.onsuccess = function (evt) { taskToAdd.id = evt.target.result; tasks.dataSource.insertAtEnd(null, taskToAdd); } } // Delete an existing task function deleteTask(listViewItem) { // Database key != ListView key var dbKey = listViewItem.data.id; var listViewKey = listViewItem.key; // Remove item from db and, if success, remove item from ListView var transaction = db.transaction("tasks", "readwrite"); var deleteRequest = transaction.objectStore("tasks").delete(dbKey); deleteRequest.onsuccess = function () { tasks.dataSource.remove(listViewKey); } } // Expose the data source and functions WinJS.Namespace.define("TaskList", { tasks: tasks, addTask: addTask, deleteTask: deleteTask }); })(); Summary I wrote this blog entry because I wanted to create a walkthrough of building a simple database-driven application. In particular, I wanted to demonstrate how you can use a ListView control with an IndexedDB database to store and retrieve database data.

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  • Metro Walkthrough: Creating a Task List with a ListView and IndexedDB

    - by Stephen.Walther
    The goal of this blog entry is to describe how you can work with data in a Metro style application written with JavaScript. In particular, we create a super simple Task List application which enables you to create and delete tasks. Here’s a video which demonstrates how the Task List application works: In order to build this application, I had to take advantage of several features of the WinJS library and technologies including: IndexedDB – The Task List application stores data in an IndexedDB database. HTML5 Form Validation – The Task List application uses HTML5 validation to ensure that a required field has a value. ListView Control – The Task List application displays the tasks retrieved from the IndexedDB database in a WinJS ListView control. Creating the IndexedDB Database The Task List application stores all of its data in an IndexedDB database named TasksDB. This database is opened/created with the following code: var db; var req = window.msIndexedDB.open("TasksDB", 1); req.onerror = function () { console.log("Could not open database"); }; req.onupgradeneeded = function (evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement:true }); }; The msIndexedDB.open() method accepts two parameters: the name of the database to open and the version of the database to open. If a database with a matching version already exists, then calling the msIndexedDB.open() method opens a connection to the existing database. If the database does not exist then the upgradeneeded event is raised. You handle the upgradeneeded event to create a new database. In the code above, the upgradeneeded event handler creates an object store named “tasks” (An object store roughly corresponds to a database table). When you add items to the tasks object store then each item gets an id property with an auto-incremented value automatically. The code above also includes an error event handler. If the IndexedDB database cannot be opened or created, for whatever reason, then an error message is written to the Visual Studio JavaScript Console window. Displaying a List of Tasks The TaskList application retrieves its list of tasks from the tasks object store, which we created above, and displays the list of tasks in a ListView control. Here is how the ListView control is declared: <div id="tasksListView" data-win-control="WinJS.UI.ListView" data-win-options="{ itemDataSource: TaskList.tasks.dataSource, itemTemplate: select('#taskTemplate'), tapBehavior: 'toggleSelect', selectionMode: 'multi', layout: { type: WinJS.UI.ListLayout } }"> </div> The ListView control is bound to the TaskList.tasks.dataSource data source. The TaskList.tasks.dataSource is created with the following code: // Create the data source var tasks = new WinJS.Binding.List(); // Open the database var db; var req = window.msIndexedDB.open("TasksDB", 1); req.onerror = function () { console.log("Could not open database"); }; req.onupgradeneeded = function (evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement:true }); }; // Load the data source with data from the database req.onsuccess = function () { db = req.result; var tran = db.transaction("tasks"); tran.objectStore("tasks").openCursor().onsuccess = function(event) { var cursor = event.target.result; tasks.dataSource.beginEdits(); if (cursor) { tasks.dataSource.insertAtEnd(null, cursor.value); cursor.continue(); } else { tasks.dataSource.endEdits(); }; }; }; // Expose the data source and functions WinJS.Namespace.define("TaskList", { tasks: tasks }); Notice the success event handler. This handler is called when a database is successfully opened/created. In the code above, all of the items from the tasks object store are retrieved into a cursor and added to a WinJS.Binding.List object named tasks. Because the ListView control is bound to the WinJS.Binding.List object, copying the tasks from the object store into the WinJS.Binding.List object causes the tasks to appear in the ListView: Adding a New Task You add a new task in the Task List application by entering the title of a new task into an HTML form and clicking the Add button. Here’s the markup for creating the form: <form id="addTaskForm"> <input id="newTaskTitle" title="New Task" required /> <button>Add</button> </form> Notice that the INPUT element includes a required attribute. In a Metro application, you can take advantage of HTML5 Validation to validate form fields. If you don’t enter a value for the newTaskTitle field then the following validation error message is displayed: For a brief introduction to HTML5 validation, see my previous blog entry: http://stephenwalther.com/blog/archive/2012/03/13/html5-form-validation.aspx When you click the Add button, the form is submitted and the form submit event is raised. The following code is executed in the default.js file: // Handle Add Task document.getElementById("addTaskForm").addEventListener("submit", function (evt) { evt.preventDefault(); var newTaskTitle = document.getElementById("newTaskTitle"); TaskList.addTask({ title: newTaskTitle.value }); newTaskTitle.value = ""; }); The code above retrieves the title of the new task and calls the addTask() method in the tasks.js file. Here’s the code for the addTask() method which is responsible for actually adding the new task to the IndexedDB database: // Add a new task function addTask(taskToAdd) { var transaction = db.transaction("tasks", IDBTransaction.READ_WRITE); var addRequest = transaction.objectStore("tasks").add(taskToAdd); addRequest.onsuccess = function (evt) { taskToAdd.id = evt.target.result; tasks.dataSource.insertAtEnd(null, taskToAdd); } } The code above does two things. First, it adds the new task to the tasks object store in the IndexedDB database. Second, it adds the new task to the data source bound to the ListView. The dataSource.insertAtEnd() method is called to add the new task to the data source so the new task will appear in the ListView (with a nice little animation). Deleting Existing Tasks The Task List application enables you to select one or more tasks by clicking or tapping on one or more tasks in the ListView. When you click the Delete button, the selected tasks are removed from both the IndexedDB database and the ListView. For example, in the following screenshot, two tasks are selected. The selected tasks appear with a teal background and a checkmark: When you click the Delete button, the following code in the default.js file is executed: // Handle Delete Tasks document.getElementById("btnDeleteTasks").addEventListener("click", function (evt) { tasksListView.winControl.selection.getItems().then(function(items) { items.forEach(function (item) { TaskList.deleteTask(item); }); }); }); The selected tasks are retrieved with the TaskList selection.getItem() method. In the code above, the deleteTask() method is called for each of the selected tasks. Here’s the code for the deleteTask() method: // Delete an existing task function deleteTask(listViewItem) { // Database key != ListView key var dbKey = listViewItem.data.id; var listViewKey = listViewItem.key; // Remove item from db and, if success, remove item from ListView var transaction = db.transaction("tasks", IDBTransaction.READ_WRITE); var deleteRequest = transaction.objectStore("tasks").delete(dbKey); deleteRequest.onsuccess = function () { tasks.dataSource.remove(listViewKey); } } This code does two things: it deletes the existing task from the database and removes the existing task from the ListView. In both cases, the right task is removed by using the key associated with the task. However, the task key is different in the case of the database and in the case of the ListView. In the case of the database, the task key is the value of the task id property. In the case of the ListView, on the other hand, the task key is auto-generated by the ListView. When the task is removed from the ListView, an animation is used to collapse the tasks which appear above and below the task which was removed. The Complete Code Above, I did a lot of jumping around between different files in the application and I left out sections of code. For the sake of completeness, I want to include the entire code here: the default.html, default.js, and tasks.js files. Here are the contents of the default.html file. This file contains the UI for the Task List application: <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Task List</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- TaskList references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> <script type="text/javascript" src="js/tasks.js"></script> <style type="text/css"> body { font-size: x-large; } form { display: inline; } #appContainer { margin: 20px; width: 600px; } .win-container { padding: 10px; } </style> </head> <body> <div> <!-- Templates --> <div id="taskTemplate" data-win-control="WinJS.Binding.Template"> <div> <span data-win-bind="innerText:title"></span> </div> </div> <h1>Super Task List</h1> <div id="appContainer"> <form id="addTaskForm"> <input id="newTaskTitle" title="New Task" required /> <button>Add</button> </form> <button id="btnDeleteTasks">Delete</button> <div id="tasksListView" data-win-control="WinJS.UI.ListView" data-win-options="{ itemDataSource: TaskList.tasks.dataSource, itemTemplate: select('#taskTemplate'), tapBehavior: 'toggleSelect', selectionMode: 'multi', layout: { type: WinJS.UI.ListLayout } }"> </div> </div> </div> </body> </html> Here is the code for the default.js file. This code wires up the Add Task form and Delete button: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { WinJS.UI.processAll().then(function () { // Get reference to Tasks ListView var tasksListView = document.getElementById("tasksListView"); // Handle Add Task document.getElementById("addTaskForm").addEventListener("submit", function (evt) { evt.preventDefault(); var newTaskTitle = document.getElementById("newTaskTitle"); TaskList.addTask({ title: newTaskTitle.value }); newTaskTitle.value = ""; }); // Handle Delete Tasks document.getElementById("btnDeleteTasks").addEventListener("click", function (evt) { tasksListView.winControl.selection.getItems().then(function(items) { items.forEach(function (item) { TaskList.deleteTask(item); }); }); }); }); } }; app.start(); })(); Finally, here is the tasks.js file. This file contains all of the code for opening, creating, and interacting with IndexedDB: (function () { "use strict"; // Create the data source var tasks = new WinJS.Binding.List(); // Open the database var db; var req = window.msIndexedDB.open("TasksDB", 1); req.onerror = function () { console.log("Could not open database"); }; req.onupgradeneeded = function (evt) { var newDB = evt.target.result; newDB.createObjectStore("tasks", { keyPath: "id", autoIncrement:true }); }; // Load the data source with data from the database req.onsuccess = function () { db = req.result; var tran = db.transaction("tasks"); tran.objectStore("tasks").openCursor().onsuccess = function(event) { var cursor = event.target.result; tasks.dataSource.beginEdits(); if (cursor) { tasks.dataSource.insertAtEnd(null, cursor.value); cursor.continue(); } else { tasks.dataSource.endEdits(); }; }; }; // Add a new task function addTask(taskToAdd) { var transaction = db.transaction("tasks", IDBTransaction.READ_WRITE); var addRequest = transaction.objectStore("tasks").add(taskToAdd); addRequest.onsuccess = function (evt) { taskToAdd.id = evt.target.result; tasks.dataSource.insertAtEnd(null, taskToAdd); } } // Delete an existing task function deleteTask(listViewItem) { // Database key != ListView key var dbKey = listViewItem.data.id; var listViewKey = listViewItem.key; // Remove item from db and, if success, remove item from ListView var transaction = db.transaction("tasks", IDBTransaction.READ_WRITE); var deleteRequest = transaction.objectStore("tasks").delete(dbKey); deleteRequest.onsuccess = function () { tasks.dataSource.remove(listViewKey); } } // Expose the data source and functions WinJS.Namespace.define("TaskList", { tasks: tasks, addTask: addTask, deleteTask: deleteTask }); })(); Summary I wrote this blog entry because I wanted to create a walkthrough of building a simple database-driven application. In particular, I wanted to demonstrate how you can use a ListView control with an IndexedDB database to store and retrieve database data.

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  • CodePlex Daily Summary for Monday, February 21, 2011

    CodePlex Daily Summary for Monday, February 21, 2011Popular ReleasesA2Command: 2011-02-21 - Version 1.0: IntroductionThis is the full release version of A2Command 1.0, dated February 21, 2011. These notes supersede any prior version's notes. All prior releases may be found on the project's website at http://a2command.codeplex.com/releases/ where you can read the release notes for older versions as well as download them. This version of A2Command is intended to replace any previous version you may have downloaded in the past. There were several bug fixes made after Release Candidate 2 and all...Chiave File Encryption: Chiave 0.9: Application for file encryption and decryption using 512 Bit rijndael encyrption algorithm with simple to use UI. Its written in C# and compiled in .Net version 3.5. It incorporates features of Windows 7 like Jumplists, Taskbar progress and Aero Glass. Feedbacks are Welcome!....Rawr: Rawr 4.0.20 Beta: Rawr is now web-based. The link to use Rawr4 is: http://elitistjerks.com/rawr.phpThis is the Cataclysm Beta Release. More details can be found at the following link http://rawr.codeplex.com/Thread/View.aspx?ThreadId=237262 As of the 4.0.16 release, you can now also begin using the new Downloadable WPF version of Rawr!This is a pre-alpha release of the WPF version, there are likely to be a lot of issues. If you have a problem, please follow the Posting Guidelines and put it into the Issue Trac...Azure Storage Samples: Version 1.0 (February 2011): These downloads contain source code. Each is a complete sample that fully exercises Windows Azure Storage across blobs, queues, and tables. The difference between the downloads is implementation approach. Storage DotNet CS.zip is a .NET StorageClient library implementation in the C# language. This library come with the Windows Azure SDK. Contains helper classes for accessing blobs, queues, and tables. Storage REST CS.zip is a REST implementation in the C# language. The code to implement R...MiniTwitter: 1.66: MiniTwitter 1.66 ???? ?? ?????????? 2 ??????????????????? User Streams ?????????View Layout Replicator for Microsoft Dynamics CRM 2011: View Layout Replicator (1.0.119.18): Initial releaseWindows Phone 7 Isolated Storage Explorer: WP7 Isolated Storage Explorer v1.0 Beta: Current release features:WPF desktop explorer client Visual Studio integrated tool window explorer client (Visual Studio 2010 Professional and above) Supported operations: Refresh (isolated storage information), Add Folder, Add Existing Item, Download File, Delete Folder, Delete File Explorer supports operations running on multiple remote applications at the same time Explorer detects application disconnect (1-2 second delay) Explorer confirms operation completed status Explorer d...Advanced Explorer for Wp7: Advanced Explorer for Wp7 Version 1.4 Test8: Added option to run under Lockscreen. Fixed a bug when you open a pdf/mobi file without starting adobe reader/amazon kindle first boost loading time for folders added \Windows directory (all devices) you can now interact with the filesystem while it is loading!Game Files Open - Map Editor: Game Files Open - Map Editor Beta 2 v1.0.0.0: The 2° beta release of the Map Editor, we have fixed a big bug of the files regen.Document.Editor: 2011.6: Whats new for Document.Editor 2011.6: New Left to Right and Left to Right support New Indent more/less support Improved Home tab Improved Tooltips/shortcut keys Minor Bug Fix's, improvements and speed upsCatel - WPF and Silverlight MVVM library: 1.2: Catel history ============= (+) Added (*) Changed (-) Removed (x) Error / bug (fix) For more information about issues or new feature requests, please visit: http://catel.codeplex.com =========== Version 1.2 =========== Release date: ============= 2011/02/17 Added/fixed: ============ (+) DataObjectBase now supports Isolated Storage out of the box: Person.Save(myStream) stores a whole object graph in Silverlight (+) DataObjectBase can now be converted to Json via Person.ToJson(); (+)...??????????: All-In-One Code Framework ??? 2011-02-18: ?????All-In-One Code Framework?2011??????????!!http://i3.codeplex.com/Project/Download/FileDownload.aspx?ProjectName=1code&DownloadId=128165 ?????,?????AzureBingMaps??????,??Azure,WCF, Silverlight, Window Phone????????,????????????????????????。 ???: Windows Azure SQL Azure Windows Azure AppFabric Windows Live Messenger Connect Bing Maps ?????: ??????HTML??? ??Windows PC?Mac?Silverlight??? ??Windows Phone?Silverlight??? ?????:http://blog.csdn.net/sjb5201/archive/2011...Image.Viewer: 2011: First version of 2011Silverlight Toolkit: Silverlight for Windows Phone Toolkit - Feb 2011: Silverlight for Windows Phone Toolkit OverviewSilverlight for Windows Phone Toolkit offers developers additional controls for Windows Phone application development, designed to match the rich user experience of the Windows Phone 7. Suggestions? Features? Questions? Ask questions in the Create.msdn.com forum. Add bugs or feature requests to the Issue Tracker. Help us shape the Silverlight Toolkit with your feedback! Please clearly indicate that the work items and issues are for the phone t...VsTortoise - a TortoiseSVN add-in for Microsoft Visual Studio: VsTortoise Build 29 Beta: Note: This release does not work with custom VsTortoise toolbars. These get removed every time when you shutdown Visual Studio. (#7940) Build 29 (beta)New: Added VsTortoise Solution Explorer integration for Web Project Folder, Web Folder and Web Item. Fix: TortoiseProc was called with invalid parameters, when using TSVN 1.4.x or older #7338 (thanks psifive) Fix: Add-in does not work, when "TortoiseSVN/bin" is not added to PATH environment variable #7357 Fix: Missing error message when ...Sense/Net CMS - Enterprise Content Management: SenseNet 6.0.3 Community Edition: Sense/Net 6.0.3 Community Edition We are happy to introduce you the latest version of Sense/Net with integrated ECM Workflow capabilities! In the past weeks we have been working hard to migrate the product to .Net 4 and include a workflow framework in Sense/Net built upon Windows Workflow Foundation 4. This brand new feature enables developers to define and develop workflows, and supports users when building and setting up complicated business processes involving content creation and response...thinktecture WSCF.blue: WSCF.blue V1 Update (1.0.11): Features Added a new option that allows properties on data contract types to be marked as virtual. Bug Fixes Fixed a bug caused by certain project properties not being available on Web Service Software Factory projects. Fixed a bug that could result in the WrapperName value of the MessageContractAttribute being incorrect when the Adjust Casing option is used. The menu item code now caters for CommandBar instances that are not available. For example the Web Item CommandBar does not exist ...AllNewsManager.NET: AllNewsManager.NET 1.3: AllNewsManager.NET 1.3. This new version provide several new features, improvements and bug fixes. Some new features: Online Users. Avatars. Copy function (to create a new article from another one). SEO improvements (friendly urls). New admin buttons. And more...Facebook Graph Toolkit: Facebook Graph Toolkit 0.8: Version 0.8 (15 Feb 2011)moved to Beta stage publish photo feature "email" field of User object added new Graph Api object: Group, Event new Graph Api connection: likes, groups, eventsDJME - The jQuery extensions for ASP.NET MVC: DJME2 -The jQuery extensions for ASP.NET MVC beta2: The source code and runtime library for DJME2. For more product info you can goto http://www.dotnetage.com/djme.html What is new ?The Grid extension added The ModelBinder added which helping you create Bindable data Action. The DnaFor() control factory added that enabled Model bindable extensions. Enhance the ListBox , ComboBox data binding.New ProjectsAuto-mobile Forum: Automobileforum is a website regarding cars where users can share their ideas about cars and whatever information they want about a car they can get that from this website. The language used for development of this website is ASP.NET Azure Storage Samples: Azure Storage Samples are Windows Azure Storage code samples. They show how to perform every Windows Azure Storage operation for blobs, queues, and tables. There are 2 identical implementations, one using REST and the other using the .NET Storage Client Library (both in C#).b1234: b1234 is b1234betrayal: bahothBungee Jumper: This is a community website for a sport known as Bungee Jumping which is one of the most dangerous adventure sport. Chiave File Encryption: Application for file encryption and decryption using 512 Bit Rijndael encryption algorithm with simple UI to use. Its written in C# and compiled in .Net version 3.5, it incorporates features of Windows 7 like Jumplists, Taskbar progress and Aero Glass.DecEncIT: DecEncIT rend l’expérience de l’utilisateur commun avec la cryptographie (cryptage) plus aisée. Pas de soucies pour les réglages et les termes techniques, vagues et difficiles à comprendre ; inclus également une option pour automatiser toutes les tâches recommandées. VB.Net/3.5ELearningTutorial: A list of tutorialsExtjs Practice - Open our extj journey: ????extjs 1.demo ?? 2.partice ?? 3.work ??Functional: This class library for .NET 3.5 and 4.0 provides extension methods for delegates, to help with functional style programming.HauntedNetworking: HauntedNetworking is a site where people can share their paranormal experiences and related photographs. They can also share pictures of haunted and scary places across the world.KharaSoft Nexus: Nexus is the last inbox you'll ever need.Kojax: kojax projectLEAD - Learn Execute And Develop: It’s a portal to share your knowledge, learn from blogs, wikis, post your questions in query board, learn new things under video training, Execute and develop these, helping gaining knowledge.Luac For 5.1 ????: luac??????? Lunar Lander: Simple WPF Lunar Lander simulator, with reactive intelligent agent autopilot.MasterSchool: Tworzenie swiadectwmovies blogspot: The Movies blog- spot is an interactive site for the information related to movies, actors, personnel and fictional characters features. MvcTemplates: MvcTemplates is a project devoted to creating a complete suite of Razor Editor and Display templates that utilize attributes, built in models, and jQuery. It is developed in C# and packages the templates into an easy to use dll.MySearcher: Quickly and easily search the major search engines with MySearcher. No clicking around, no switching windows; No matter how many windows you have open, or what you're doing, Searching the major search engines is as simple as moving your mouse to the side of the screen!Photography in Kerala: Photography in Kerala's a website which makes easier for people who are into naturistic Photography to share their photos and other Info of Kerala(also called God's own country).You'll no longer have to search about Kerala,Or share your own info/pics here.Developed in ASP.Net.Pixels(Storage Engine): Pixels(Storage Engine)PortsManager: C# Project to Simplify working with Ports Currnetly it's working with COMs in Receive only and soon it'll be updated to work in send and expand the library to handle send informations even in network.Public Web Browser: Public Web Browser is a webbrowser client with alot of featuresRealStatus - MS Communicator 2007 & A Traffic Light Indicator Hardware: A demonstration of a traffic light indicator hardware corresponding to status events of MS Communicator in real-time. A demo video can be found here: http://www.youtube.com/watch?v=GwgfSVeXVksSABnzbdNet: A SABnzbd monitor and administrator. Built in C# WPF.Sendill: Kerfi fyrir sendibílastöðvarT4 Metadata and Data Annotations Template: This T4 template handles generating metadata classes from an Entity Framework 4 model and decorates primitive and navigation properties with data annotation attributes such as [Required] and [StringLength]. The [DataType] attribute is also applied when appropriate.urlshorten service: urlshorten service need storoom @ http://storoom.codeplex.com/ developed in vb.netuVersionClientCache: uVersionClientCache is a custom macro to always automatically version (URL querstring parameter) your files based on a MD5 hash of the file contents or file last modified date to prevent issues with client browsers caching an old file after you have changed it.Video Game Network Library: A lightweight network library written in C++ for video games.View Layout Replicator for Microsoft Dynamics CRM 2011: View Layout Replicator make it easier for Microsoft Dynamics CRM 2011 customizers to copying the layout of a view and paste it to the layout of other views in the same entityVLC MakeIT: This is virtual learning center yogaasana4you: The website is on Yoga Asana for the community who want to feel the amazing experience of Yoga asana - Yoga Exercises and Postures.

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  • Stacking two pictures with captions side by side and centered in Wordpress

    - by Jim
    Hi all - this is driving me absolutely nuts. I'm not the most experienced with CSS, so I'm hoping it is something simple. I'm running Wordpress 2.9.2 with "The Morning After" theme. I am trying to write a post where I want to display two small pictures, with captions, side-by-side and centered in the middle of the page. Here is the HTML code I am using to display the images: [caption align="alignnone" width="150" caption="Protein rest"] <a href="http://www.mysite.com/wp-content/uploads/2008/06/protein-rest.jpg"> <img title="Mash during protein rest" src="http://www.mysite.com/wp-content/uploads/2008/06/protein-rest-150x144.jpg" alt="Mash during protein rest" width="150" height="144" /> </a>[/caption] [caption align="alignnone" width="143" caption="Saccharification rest" captionalign="center"] <a href="http://www.mysite.com/wp-content/uploads/2008/06/saccharification-rest.jpg"> <img title="Mash during saccharification rest" src="http://www.mysite.com/wp-content/uploads/2008/06/saccharification-rest-143x150.jpg" alt="Mash during saccharification rest" width="143" height="150" /> </a>[/caption] I tried using "aligncenter" and "alignleft" for the caption align - if I use "alignleft" the pictures are lined up perfectly, but all the way to the left of the page. If I use "aligncenter" the pics are in the center, but stacked one on top of the other. My first thought was to wrap the images in a div using: <div style="text-align:center;">image code</div> but that doesn't work. Now, if I wrap in a centered div like that and omit the [caption] tags, it works, but I need the captions. Those caption tags are translated by Wordpress into it's own div of class wp-caption. I've also tried wrapping each separate image in its own div within a parent centered div wrapper. Here is the pertinent parts of the style.css - please let me know if you need any other info, and if you can help me, I will postpone jumping off the nearest bridge! Thanks!! Style.css: .aligncenter, div.aligncenter { display: block; margin: 14px auto; } .alignleft { float: left; margin: 0 14px 10px 0; } .alignright { float: right; margin: 0 0 10px 14px; } .wp-caption { border: 1px solid #ddd; text-align: center; background-color: #f3f3f3; padding-top: 4px; /* optional rounded corners for browsers that support it */ -moz-border-radius: 3px; -khtml-border-radius: 3px; -webkit-border-radius: 3px; border-radius: 3px; } .wp-caption img { margin: 0; padding: 0; border: 0 none; } .wp-caption p.wp-caption-text { font-size: 11px; line-height: 14px; padding: 5px 4px 5px 5px; margin: 0; } PS - I am aware of the Gallery feature available in Wordpress, but would like to avoid it and would love to understand why wrapping in a div doesn't move the whole kit to the center. Finally, just for the sake of completeness, here is the source of the page when loaded using the div wrapper and image code as above (so you can see how Wordpress translates the caption tags): <div style="text-align:center;"> <div class="wp-caption alignnone" style="width: 160px"> <a href="http://www.mysite.com/wp-content/uploads/2008/06/protein-rest.jpg"> <img title="Mash during protein rest" src="http://www.mysite.com/wp-content/uploads/2008/06/protein-rest-150x144.jpg" alt="Mash during protein rest" width="150" height="144" /> </a> <p class="wp-caption-text" style="text-align:center">Protein rest</p> </div> <div class="wp-caption alignnone" style="width: 153px"> <a href="http://www.mysite.com/wp-content/uploads/2008/06/saccharification-rest.jpg"> <img title="Mash during saccharification rest" src="http://www.mysite.com/wp-content/uploads/2008/06/saccharification-rest-143x150.jpg" alt="Mash during saccharification rest" width="143" height="150" /> </a> <p class="wp-caption-text" style="text-align:center">Saccharification rest</p> </div> </div>

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  • C#/.NET Little Wonders: Interlocked CompareExchange()

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Two posts ago, I discussed the Interlocked Add(), Increment(), and Decrement() methods (here) for adding and subtracting values in a thread-safe, lightweight manner.  Then, last post I talked about the Interlocked Read() and Exchange() methods (here) for safely and efficiently reading and setting 32 or 64 bit values (or references).  This week, we’ll round out the discussion by talking about the Interlocked CompareExchange() method and how it can be put to use to exchange a value if the current value is what you expected it to be. Dirty reads can lead to bad results Many of the uses of Interlocked that we’ve explored so far have centered around either reading, setting, or adding values.  But what happens if you want to do something more complex such as setting a value based on the previous value in some manner? Perhaps you were creating an application that reads a current balance, applies a deposit, and then saves the new modified balance, where of course you’d want that to happen atomically.  If you read the balance, then go to save the new balance and between that time the previous balance has already changed, you’ll have an issue!  Think about it, if we read the current balance as $400, and we are applying a new deposit of $50.75, but meanwhile someone else deposits $200 and sets the total to $600, but then we write a total of $450.75 we’ve lost $200! Now, certainly for int and long values we can use Interlocked.Add() to handles these cases, and it works well for that.  But what if we want to work with doubles, for example?  Let’s say we wanted to add the numbers from 0 to 99,999 in parallel.  We could do this by spawning several parallel tasks to continuously add to a total: 1: double total = 0; 2:  3: Parallel.For(0, 10000, next => 4: { 5: total += next; 6: }); Were this run on one thread using a standard for loop, we’d expect an answer of 4,999,950,000 (the sum of all numbers from 0 to 99,999).  But when we run this in parallel as written above, we’ll likely get something far off.  The result of one of my runs, for example, was 1,281,880,740.  That is way off!  If this were banking software we’d be in big trouble with our clients.  So what happened?  The += operator is not atomic, it will read in the current value, add the result, then store it back into the total.  At any point in all of this another thread could read a “dirty” current total and accidentally “skip” our add.   So, to clean this up, we could use a lock to guarantee concurrency: 1: double total = 0.0; 2: object locker = new object(); 3:  4: Parallel.For(0, count, next => 5: { 6: lock (locker) 7: { 8: total += next; 9: } 10: }); Which will give us the correct result of 4,999,950,000.  One thing to note is that locking can be heavy, especially if the operation being locked over is trivial, or the life of the lock is a high percentage of the work being performed concurrently.  In the case above, the lock consumes pretty much all of the time of each parallel task – and the task being locked on is relatively trivial. Now, let me put in a disclaimer here before we go further: For most uses, lock is more than sufficient for your needs, and is often the simplest solution!    So, if lock is sufficient for most needs, why would we ever consider another solution?  The problem with locking is that it can suspend execution of your thread while it waits for the signal that the lock is free.  Moreover, if the operation being locked over is trivial, the lock can add a very high level of overhead.  This is why things like Interlocked.Increment() perform so well, instead of locking just to perform an increment, we perform the increment with an atomic, lockless method. As with all things performance related, it’s important to profile before jumping to the conclusion that you should optimize everything in your path.  If your profiling shows that locking is causing a high level of waiting in your application, then it’s time to consider lighter alternatives such as Interlocked. CompareExchange() – Exchange existing value if equal some value So let’s look at how we could use CompareExchange() to solve our problem above.  The general syntax of CompareExchange() is: T CompareExchange<T>(ref T location, T newValue, T expectedValue) If the value in location == expectedValue, then newValue is exchanged.  Either way, the value in location (before exchange) is returned. Actually, CompareExchange() is not one method, but a family of overloaded methods that can take int, long, float, double, pointers, or references.  It cannot take other value types (that is, can’t CompareExchange() two DateTime instances directly).  Also keep in mind that the version that takes any reference type (the generic overload) only checks for reference equality, it does not call any overridden Equals(). So how does this help us?  Well, we can grab the current total, and exchange the new value if total hasn’t changed.  This would look like this: 1: // grab the snapshot 2: double current = total; 3:  4: // if the total hasn’t changed since I grabbed the snapshot, then 5: // set it to the new total 6: Interlocked.CompareExchange(ref total, current + next, current); So what the code above says is: if the amount in total (1st arg) is the same as the amount in current (3rd arg), then set total to current + next (2nd arg).  This check and exchange pair is atomic (and thus thread-safe). This works if total is the same as our snapshot in current, but the problem, is what happens if they aren’t the same?  Well, we know that in either case we will get the previous value of total (before the exchange), back as a result.  Thus, we can test this against our snapshot to see if it was the value we expected: 1: // if the value returned is != current, then our snapshot must be out of date 2: // which means we didn't (and shouldn't) apply current + next 3: if (Interlocked.CompareExchange(ref total, current + next, current) != current) 4: { 5: // ooops, total was not equal to our snapshot in current, what should we do??? 6: } So what do we do if we fail?  That’s up to you and the problem you are trying to solve.  It’s possible you would decide to abort the whole transaction, or perhaps do a lightweight spin and try again.  Let’s try that: 1: double current = total; 2:  3: // make first attempt... 4: if (Interlocked.CompareExchange(ref total, current + i, current) != current) 5: { 6: // if we fail, go into a spin wait, spin, and try again until succeed 7: var spinner = new SpinWait(); 8:  9: do 10: { 11: spinner.SpinOnce(); 12: current = total; 13: } 14: while (Interlocked.CompareExchange(ref total, current + i, current) != current); 15: } 16:  This is not trivial code, but it illustrates a possible use of CompareExchange().  What we are doing is first checking to see if we succeed on the first try, and if so great!  If not, we create a SpinWait and then repeat the process of SpinOnce(), grab a fresh snapshot, and repeat until CompareExchnage() succeeds.  You may wonder why not a simple do-while here, and the reason it’s more efficient to only create the SpinWait until we absolutely know we need one, for optimal efficiency. Though not as simple (or maintainable) as a simple lock, this will perform better in many situations.  Comparing an unlocked (and wrong) version, a version using lock, and the Interlocked of the code, we get the following average times for multiple iterations of adding the sum of 100,000 numbers: 1: Unlocked money average time: 2.1 ms 2: Locked money average time: 5.1 ms 3: Interlocked money average time: 3 ms So the Interlocked.CompareExchange(), while heavier to code, came in lighter than the lock, offering a good compromise of safety and performance when we need to reduce contention. CompareExchange() - it’s not just for adding stuff… So that was one simple use of CompareExchange() in the context of adding double values -- which meant we couldn’t have used the simpler Interlocked.Add() -- but it has other uses as well. If you think about it, this really works anytime you want to create something new based on a current value without using a full lock.  For example, you could use it to create a simple lazy instantiation implementation.  In this case, we want to set the lazy instance only if the previous value was null: 1: public static class Lazy<T> where T : class, new() 2: { 3: private static T _instance; 4:  5: public static T Instance 6: { 7: get 8: { 9: // if current is null, we need to create new instance 10: if (_instance == null) 11: { 12: // attempt create, it will only set if previous was null 13: Interlocked.CompareExchange(ref _instance, new T(), (T)null); 14: } 15:  16: return _instance; 17: } 18: } 19: } So, if _instance == null, this will create a new T() and attempt to exchange it with _instance.  If _instance is not null, then it does nothing and we discard the new T() we created. This is a way to create lazy instances of a type where we are more concerned about locking overhead than creating an accidental duplicate which is not used.  In fact, the BCL implementation of Lazy<T> offers a similar thread-safety choice for Publication thread safety, where it will not guarantee only one instance was created, but it will guarantee that all readers get the same instance.  Another possible use would be in concurrent collections.  Let’s say, for example, that you are creating your own brand new super stack that uses a linked list paradigm and is “lock free”.  We could use Interlocked.CompareExchange() to be able to do a lockless Push() which could be more efficient in multi-threaded applications where several threads are pushing and popping on the stack concurrently. Yes, there are already concurrent collections in the BCL (in .NET 4.0 as part of the TPL), but it’s a fun exercise!  So let’s assume we have a node like this: 1: public sealed class Node<T> 2: { 3: // the data for this node 4: public T Data { get; set; } 5:  6: // the link to the next instance 7: internal Node<T> Next { get; set; } 8: } Then, perhaps, our stack’s Push() operation might look something like: 1: public sealed class SuperStack<T> 2: { 3: private volatile T _head; 4:  5: public void Push(T value) 6: { 7: var newNode = new Node<int> { Data = value, Next = _head }; 8:  9: if (Interlocked.CompareExchange(ref _head, newNode, newNode.Next) != newNode.Next) 10: { 11: var spinner = new SpinWait(); 12:  13: do 14: { 15: spinner.SpinOnce(); 16: newNode.Next = _head; 17: } 18: while (Interlocked.CompareExchange(ref _head, newNode, newNode.Next) != newNode.Next); 19: } 20: } 21:  22: // ... 23: } Notice a similar paradigm here as with adding our doubles before.  What we are doing is creating the new Node with the data to push, and with a Next value being the original node referenced by _head.  This will create our stack behavior (LIFO – Last In, First Out).  Now, we have to set _head to now refer to the newNode, but we must first make sure it hasn’t changed! So we check to see if _head has the same value we saved in our snapshot as newNode.Next, and if so, we set _head to newNode.  This is all done atomically, and the result is _head’s original value, as long as the original value was what we assumed it was with newNode.Next, then we are good and we set it without a lock!  If not, we SpinWait and try again. Once again, this is much lighter than locking in highly parallelized code with lots of contention.  If I compare the method above with a similar class using lock, I get the following results for pushing 100,000 items: 1: Locked SuperStack average time: 6 ms 2: Interlocked SuperStack average time: 4.5 ms So, once again, we can get more efficient than a lock, though there is the cost of added code complexity.  Fortunately for you, most of the concurrent collection you’d ever need are already created for you in the System.Collections.Concurrent (here) namespace – for more information, see my Little Wonders – The Concurent Collections Part 1 (here), Part 2 (here), and Part 3 (here). Summary We’ve seen before how the Interlocked class can be used to safely and efficiently add, increment, decrement, read, and exchange values in a multi-threaded environment.  In addition to these, Interlocked CompareExchange() can be used to perform more complex logic without the need of a lock when lock contention is a concern. The added efficiency, though, comes at the cost of more complex code.  As such, the standard lock is often sufficient for most thread-safety needs.  But if profiling indicates you spend a lot of time waiting for locks, or if you just need a lock for something simple such as an increment, decrement, read, exchange, etc., then consider using the Interlocked class’s methods to reduce wait. Technorati Tags: C#,CSharp,.NET,Little Wonders,Interlocked,CompareExchange,threading,concurrency

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  • Toorcon 15 (2013)

    - by danx
    The Toorcon gang (senior staff): h1kari (founder), nfiltr8, and Geo Introduction to Toorcon 15 (2013) A Tale of One Software Bypass of MS Windows 8 Secure Boot Breaching SSL, One Byte at a Time Running at 99%: Surviving an Application DoS Security Response in the Age of Mass Customized Attacks x86 Rewriting: Defeating RoP and other Shinanighans Clowntown Express: interesting bugs and running a bug bounty program Active Fingerprinting of Encrypted VPNs Making Attacks Go Backwards Mask Your Checksums—The Gorry Details Adventures with weird machines thirty years after "Reflections on Trusting Trust" Introduction to Toorcon 15 (2013) Toorcon 15 is the 15th annual security conference held in San Diego. I've attended about a third of them and blogged about previous conferences I attended here starting in 2003. As always, I've only summarized the talks I attended and interested me enough to write about them. Be aware that I may have misrepresented the speaker's remarks and that they are not my remarks or opinion, or those of my employer, so don't quote me or them. Those seeking further details may contact the speakers directly or use The Google. For some talks, I have a URL for further information. A Tale of One Software Bypass of MS Windows 8 Secure Boot Andrew Furtak and Oleksandr Bazhaniuk Yuri Bulygin, Oleksandr ("Alex") Bazhaniuk, and (not present) Andrew Furtak Yuri and Alex talked about UEFI and Bootkits and bypassing MS Windows 8 Secure Boot, with vendor recommendations. They previously gave this talk at the BlackHat 2013 conference. MS Windows 8 Secure Boot Overview UEFI (Unified Extensible Firmware Interface) is interface between hardware and OS. UEFI is processor and architecture independent. Malware can replace bootloader (bootx64.efi, bootmgfw.efi). Once replaced can modify kernel. Trivial to replace bootloader. Today many legacy bootkits—UEFI replaces them most of them. MS Windows 8 Secure Boot verifies everything you load, either through signatures or hashes. UEFI firmware relies on secure update (with signed update). You would think Secure Boot would rely on ROM (such as used for phones0, but you can't do that for PCs—PCs use writable memory with signatures DXE core verifies the UEFI boat loader(s) OS Loader (winload.efi, winresume.efi) verifies the OS kernel A chain of trust is established with a root key (Platform Key, PK), which is a cert belonging to the platform vendor. Key Exchange Keys (KEKs) verify an "authorized" database (db), and "forbidden" database (dbx). X.509 certs with SHA-1/SHA-256 hashes. Keys are stored in non-volatile (NV) flash-based NVRAM. Boot Services (BS) allow adding/deleting keys (can't be accessed once OS starts—which uses Run-Time (RT)). Root cert uses RSA-2048 public keys and PKCS#7 format signatures. SecureBoot — enable disable image signature checks SetupMode — update keys, self-signed keys, and secure boot variables CustomMode — allows updating keys Secure Boot policy settings are: always execute, never execute, allow execute on security violation, defer execute on security violation, deny execute on security violation, query user on security violation Attacking MS Windows 8 Secure Boot Secure Boot does NOT protect from physical access. Can disable from console. Each BIOS vendor implements Secure Boot differently. There are several platform and BIOS vendors. It becomes a "zoo" of implementations—which can be taken advantage of. Secure Boot is secure only when all vendors implement it correctly. Allow only UEFI firmware signed updates protect UEFI firmware from direct modification in flash memory protect FW update components program SPI controller securely protect secure boot policy settings in nvram protect runtime api disable compatibility support module which allows unsigned legacy Can corrupt the Platform Key (PK) EFI root certificate variable in SPI flash. If PK is not found, FW enters setup mode wich secure boot turned off. Can also exploit TPM in a similar manner. One is not supposed to be able to directly modify the PK in SPI flash from the OS though. But they found a bug that they can exploit from User Mode (undisclosed) and demoed the exploit. It loaded and ran their own bootkit. The exploit requires a reboot. Multiple vendors are vulnerable. They will disclose this exploit to vendors in the future. Recommendations: allow only signed updates protect UEFI fw in ROM protect EFI variable store in ROM Breaching SSL, One Byte at a Time Yoel Gluck and Angelo Prado Angelo Prado and Yoel Gluck, Salesforce.com CRIME is software that performs a "compression oracle attack." This is possible because the SSL protocol doesn't hide length, and because SSL compresses the header. CRIME requests with every possible character and measures the ciphertext length. Look for the plaintext which compresses the most and looks for the cookie one byte-at-a-time. SSL Compression uses LZ77 to reduce redundancy. Huffman coding replaces common byte sequences with shorter codes. US CERT thinks the SSL compression problem is fixed, but it isn't. They convinced CERT that it wasn't fixed and they issued a CVE. BREACH, breachattrack.com BREACH exploits the SSL response body (Accept-Encoding response, Content-Encoding). It takes advantage of the fact that the response is not compressed. BREACH uses gzip and needs fairly "stable" pages that are static for ~30 seconds. It needs attacker-supplied content (say from a web form or added to a URL parameter). BREACH listens to a session's requests and responses, then inserts extra requests and responses. Eventually, BREACH guesses a session's secret key. Can use compression to guess contents one byte at-a-time. For example, "Supersecret SupersecreX" (a wrong guess) compresses 10 bytes, and "Supersecret Supersecret" (a correct guess) compresses 11 bytes, so it can find each character by guessing every character. To start the guess, BREACH needs at least three known initial characters in the response sequence. Compression length then "leaks" information. Some roadblocks include no winners (all guesses wrong) or too many winners (multiple possibilities that compress the same). The solutions include: lookahead (guess 2 or 3 characters at-a-time instead of 1 character). Expensive rollback to last known conflict check compression ratio can brute-force first 3 "bootstrap" characters, if needed (expensive) block ciphers hide exact plain text length. Solution is to align response in advance to block size Mitigations length: use variable padding secrets: dynamic CSRF tokens per request secret: change over time separate secret to input-less servlets Future work eiter understand DEFLATE/GZIP HTTPS extensions Running at 99%: Surviving an Application DoS Ryan Huber Ryan Huber, Risk I/O Ryan first discussed various ways to do a denial of service (DoS) attack against web services. One usual method is to find a slow web page and do several wgets. Or download large files. Apache is not well suited at handling a large number of connections, but one can put something in front of it Can use Apache alternatives, such as nginx How to identify malicious hosts short, sudden web requests user-agent is obvious (curl, python) same url requested repeatedly no web page referer (not normal) hidden links. hide a link and see if a bot gets it restricted access if not your geo IP (unless the website is global) missing common headers in request regular timing first seen IP at beginning of attack count requests per hosts (usually a very large number) Use of captcha can mitigate attacks, but you'll lose a lot of genuine users. Bouncer, goo.gl/c2vyEc and www.github.com/rawdigits/Bouncer Bouncer is software written by Ryan in netflow. Bouncer has a small, unobtrusive footprint and detects DoS attempts. It closes blacklisted sockets immediately (not nice about it, no proper close connection). Aggregator collects requests and controls your web proxies. Need NTP on the front end web servers for clean data for use by bouncer. Bouncer is also useful for a popularity storm ("Slashdotting") and scraper storms. Future features: gzip collection data, documentation, consumer library, multitask, logging destroyed connections. Takeaways: DoS mitigation is easier with a complete picture Bouncer designed to make it easier to detect and defend DoS—not a complete cure Security Response in the Age of Mass Customized Attacks Peleus Uhley and Karthik Raman Peleus Uhley and Karthik Raman, Adobe ASSET, blogs.adobe.com/asset/ Peleus and Karthik talked about response to mass-customized exploits. Attackers behave much like a business. "Mass customization" refers to concept discussed in the book Future Perfect by Stan Davis of Harvard Business School. Mass customization is differentiating a product for an individual customer, but at a mass production price. For example, the same individual with a debit card receives basically the same customized ATM experience around the world. Or designing your own PC from commodity parts. Exploit kits are another example of mass customization. The kits support multiple browsers and plugins, allows new modules. Exploit kits are cheap and customizable. Organized gangs use exploit kits. A group at Berkeley looked at 77,000 malicious websites (Grier et al., "Manufacturing Compromise: The Emergence of Exploit-as-a-Service", 2012). They found 10,000 distinct binaries among them, but derived from only a dozen or so exploit kits. Characteristics of Mass Malware: potent, resilient, relatively low cost Technical characteristics: multiple OS, multipe payloads, multiple scenarios, multiple languages, obfuscation Response time for 0-day exploits has gone down from ~40 days 5 years ago to about ~10 days now. So the drive with malware is towards mass customized exploits, to avoid detection There's plenty of evicence that exploit development has Project Manager bureaucracy. They infer from the malware edicts to: support all versions of reader support all versions of windows support all versions of flash support all browsers write large complex, difficult to main code (8750 lines of JavaScript for example Exploits have "loose coupling" of multipe versions of software (adobe), OS, and browser. This allows specific attacks against specific versions of multiple pieces of software. Also allows exploits of more obscure software/OS/browsers and obscure versions. Gave examples of exploits that exploited 2, 3, 6, or 14 separate bugs. However, these complete exploits are more likely to be buggy or fragile in themselves and easier to defeat. Future research includes normalizing malware and Javascript. Conclusion: The coming trend is that mass-malware with mass zero-day attacks will result in mass customization of attacks. x86 Rewriting: Defeating RoP and other Shinanighans Richard Wartell Richard Wartell The attack vector we are addressing here is: First some malware causes a buffer overflow. The malware has no program access, but input access and buffer overflow code onto stack Later the stack became non-executable. The workaround malware used was to write a bogus return address to the stack jumping to malware Later came ASLR (Address Space Layout Randomization) to randomize memory layout and make addresses non-deterministic. The workaround malware used was to jump t existing code segments in the program that can be used in bad ways "RoP" is Return-oriented Programming attacks. RoP attacks use your own code and write return address on stack to (existing) expoitable code found in program ("gadgets"). Pinkie Pie was paid $60K last year for a RoP attack. One solution is using anti-RoP compilers that compile source code with NO return instructions. ASLR does not randomize address space, just "gadgets". IPR/ILR ("Instruction Location Randomization") randomizes each instruction with a virtual machine. Richard's goal was to randomize a binary with no source code access. He created "STIR" (Self-Transofrming Instruction Relocation). STIR disassembles binary and operates on "basic blocks" of code. The STIR disassembler is conservative in what to disassemble. Each basic block is moved to a random location in memory. Next, STIR writes new code sections with copies of "basic blocks" of code in randomized locations. The old code is copied and rewritten with jumps to new code. the original code sections in the file is marked non-executible. STIR has better entropy than ASLR in location of code. Makes brute force attacks much harder. STIR runs on MS Windows (PEM) and Linux (ELF). It eliminated 99.96% or more "gadgets" (i.e., moved the address). Overhead usually 5-10% on MS Windows, about 1.5-4% on Linux (but some code actually runs faster!). The unique thing about STIR is it requires no source access and the modified binary fully works! Current work is to rewrite code to enforce security policies. For example, don't create a *.{exe,msi,bat} file. Or don't connect to the network after reading from the disk. Clowntown Express: interesting bugs and running a bug bounty program Collin Greene Collin Greene, Facebook Collin talked about Facebook's bug bounty program. Background at FB: FB has good security frameworks, such as security teams, external audits, and cc'ing on diffs. But there's lots of "deep, dark, forgotten" parts of legacy FB code. Collin gave several examples of bountied bugs. Some bounty submissions were on software purchased from a third-party (but bounty claimers don't know and don't care). We use security questions, as does everyone else, but they are basically insecure (often easily discoverable). Collin didn't expect many bugs from the bounty program, but they ended getting 20+ good bugs in first 24 hours and good submissions continue to come in. Bug bounties bring people in with different perspectives, and are paid only for success. Bug bounty is a better use of a fixed amount of time and money versus just code review or static code analysis. The Bounty program started July 2011 and paid out $1.5 million to date. 14% of the submissions have been high priority problems that needed to be fixed immediately. The best bugs come from a small % of submitters (as with everything else)—the top paid submitters are paid 6 figures a year. Spammers like to backstab competitors. The youngest sumitter was 13. Some submitters have been hired. Bug bounties also allows to see bugs that were missed by tools or reviews, allowing improvement in the process. Bug bounties might not work for traditional software companies where the product has release cycle or is not on Internet. Active Fingerprinting of Encrypted VPNs Anna Shubina Anna Shubina, Dartmouth Institute for Security, Technology, and Society (I missed the start of her talk because another track went overtime. But I have the DVD of the talk, so I'll expand later) IPsec leaves fingerprints. Using netcat, one can easily visually distinguish various crypto chaining modes just from packet timing on a chart (example, DES-CBC versus AES-CBC) One can tell a lot about VPNs just from ping roundtrips (such as what router is used) Delayed packets are not informative about a network, especially if far away from the network More needed to explore about how TCP works in real life with respect to timing Making Attacks Go Backwards Fuzzynop FuzzyNop, Mandiant This talk is not about threat attribution (finding who), product solutions, politics, or sales pitches. But who are making these malware threats? It's not a single person or group—they have diverse skill levels. There's a lot of fat-fingered fumblers out there. Always look for low-hanging fruit first: "hiding" malware in the temp, recycle, or root directories creation of unnamed scheduled tasks obvious names of files and syscalls ("ClearEventLog") uncleared event logs. Clearing event log in itself, and time of clearing, is a red flag and good first clue to look for on a suspect system Reverse engineering is hard. Disassembler use takes practice and skill. A popular tool is IDA Pro, but it takes multiple interactive iterations to get a clean disassembly. Key loggers are used a lot in targeted attacks. They are typically custom code or built in a backdoor. A big tip-off is that non-printable characters need to be printed out (such as "[Ctrl]" "[RightShift]") or time stamp printf strings. Look for these in files. Presence is not proof they are used. Absence is not proof they are not used. Java exploits. Can parse jar file with idxparser.py and decomile Java file. Java typially used to target tech companies. Backdoors are the main persistence mechanism (provided externally) for malware. Also malware typically needs command and control. Application of Artificial Intelligence in Ad-Hoc Static Code Analysis John Ashaman John Ashaman, Security Innovation Initially John tried to analyze open source files with open source static analysis tools, but these showed thousands of false positives. Also tried using grep, but tis fails to find anything even mildly complex. So next John decided to write his own tool. His approach was to first generate a call graph then analyze the graph. However, the problem is that making a call graph is really hard. For example, one problem is "evil" coding techniques, such as passing function pointer. First the tool generated an Abstract Syntax Tree (AST) with the nodes created from method declarations and edges created from method use. Then the tool generated a control flow graph with the goal to find a path through the AST (a maze) from source to sink. The algorithm is to look at adjacent nodes to see if any are "scary" (a vulnerability), using heuristics for search order. The tool, called "Scat" (Static Code Analysis Tool), currently looks for C# vulnerabilities and some simple PHP. Later, he plans to add more PHP, then JSP and Java. For more information see his posts in Security Innovation blog and NRefactory on GitHub. Mask Your Checksums—The Gorry Details Eric (XlogicX) Davisson Eric (XlogicX) Davisson Sometimes in emailing or posting TCP/IP packets to analyze problems, you may want to mask the IP address. But to do this correctly, you need to mask the checksum too, or you'll leak information about the IP. Problem reports found in stackoverflow.com, sans.org, and pastebin.org are usually not masked, but a few companies do care. If only the IP is masked, the IP may be guessed from checksum (that is, it leaks data). Other parts of packet may leak more data about the IP. TCP and IP checksums both refer to the same data, so can get more bits of information out of using both checksums than just using one checksum. Also, one can usually determine the OS from the TTL field and ports in a packet header. If we get hundreds of possible results (16x each masked nibble that is unknown), one can do other things to narrow the results, such as look at packet contents for domain or geo information. With hundreds of results, can import as CSV format into a spreadsheet. Can corelate with geo data and see where each possibility is located. Eric then demoed a real email report with a masked IP packet attached. Was able to find the exact IP address, given the geo and university of the sender. Point is if you're going to mask a packet, do it right. Eric wouldn't usually bother, but do it correctly if at all, to not create a false impression of security. Adventures with weird machines thirty years after "Reflections on Trusting Trust" Sergey Bratus Sergey Bratus, Dartmouth College (and Julian Bangert and Rebecca Shapiro, not present) "Reflections on Trusting Trust" refers to Ken Thompson's classic 1984 paper. "You can't trust code that you did not totally create yourself." There's invisible links in the chain-of-trust, such as "well-installed microcode bugs" or in the compiler, and other planted bugs. Thompson showed how a compiler can introduce and propagate bugs in unmodified source. But suppose if there's no bugs and you trust the author, can you trust the code? Hell No! There's too many factors—it's Babylonian in nature. Why not? Well, Input is not well-defined/recognized (code's assumptions about "checked" input will be violated (bug/vunerabiliy). For example, HTML is recursive, but Regex checking is not recursive. Input well-formed but so complex there's no telling what it does For example, ELF file parsing is complex and has multiple ways of parsing. Input is seen differently by different pieces of program or toolchain Any Input is a program input executes on input handlers (drives state changes & transitions) only a well-defined execution model can be trusted (regex/DFA, PDA, CFG) Input handler either is a "recognizer" for the inputs as a well-defined language (see langsec.org) or it's a "virtual machine" for inputs to drive into pwn-age ELF ABI (UNIX/Linux executible file format) case study. Problems can arise from these steps (without planting bugs): compiler linker loader ld.so/rtld relocator DWARF (debugger info) exceptions The problem is you can't really automatically analyze code (it's the "halting problem" and undecidable). Only solution is to freeze code and sign it. But you can't freeze everything! Can't freeze ASLR or loading—must have tables and metadata. Any sufficiently complex input data is the same as VM byte code Example, ELF relocation entries + dynamic symbols == a Turing Complete Machine (TM). @bxsays created a Turing machine in Linux from relocation data (not code) in an ELF file. For more information, see Rebecca "bx" Shapiro's presentation from last year's Toorcon, "Programming Weird Machines with ELF Metadata" @bxsays did same thing with Mach-O bytecode Or a DWARF exception handling data .eh_frame + glibc == Turning Machine X86 MMU (IDT, GDT, TSS): used address translation to create a Turning Machine. Page handler reads and writes (on page fault) memory. Uses a page table, which can be used as Turning Machine byte code. Example on Github using this TM that will fly a glider across the screen Next Sergey talked about "Parser Differentials". That having one input format, but two parsers, will create confusion and opportunity for exploitation. For example, CSRs are parsed during creation by cert requestor and again by another parser at the CA. Another example is ELF—several parsers in OS tool chain, which are all different. Can have two different Program Headers (PHDRs) because ld.so parses multiple PHDRs. The second PHDR can completely transform the executable. This is described in paper in the first issue of International Journal of PoC. Conclusions trusting computers not only about bugs! Bugs are part of a problem, but no by far all of it complex data formats means bugs no "chain of trust" in Babylon! (that is, with parser differentials) we need to squeeze complexity out of data until data stops being "code equivalent" Further information See and langsec.org. USENIX WOOT 2013 (Workshop on Offensive Technologies) for "weird machines" papers and videos.

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  • Red Gate Coder interviews: Robin Hellen

    - by Michael Williamson
    Robin Hellen is a test engineer here at Red Gate, and is also the latest coder I’ve interviewed. We chatted about debugging code, the roles of software engineers and testers, and why Vala is currently his favourite programming language. How did you get started with programming?It started when I was about six. My dad’s a professional programmer, and he gave me and my sister one of his old computers and taught us a bit about programming. It was an old Amiga 500 with a variant of BASIC. I don’t think I ever successfully completed anything! It was just faffing around. I didn’t really get anywhere with it.But then presumably you did get somewhere with it at some point.At some point. The PC emerged as the dominant platform, and I learnt a bit of Visual Basic. I didn’t really do much, just a couple of quick hacky things. A bit of demo animation. Took me a long time to get anywhere with programming, really.When did you feel like you did start to get somewhere?I think it was when I started doing things for someone else, which was my sister’s final year of university project. She called up my dad two days before she was due to submit, saying “We need something to display a graph!”. Dad says, “I’m too busy, go talk to your brother”. So I hacked up this ugly piece of code, sent it off and they won a prize for that project. Apparently, the graph, the bit that I wrote, was the reason they won a prize! That was when I first felt that I’d actually done something that was worthwhile. That was my first real bit of code, and the ugliest code I’ve ever written. It’s basically an array of pre-drawn line elements that I shifted round the screen to draw a very spikey graph.When did you decide that programming might actually be something that you wanted to do as a career?It’s not really a decision I took, I always wanted to do something with computers. And I had to take a gap year for uni, so I was looking for twelve month internships. I applied to Red Gate, and they gave me a job as a tester. And that’s where I really started having to write code well. To a better standard that I had been up to that point.How did you find coming to Red Gate and working with other coders?I thought it was really nice. I learnt so much just from other people around. I think one of the things that’s really great is that people are just willing to help you learn. Instead of “Don’t you know that, you’re so stupid”, it’s “You can just do it this way”.If you could go back to the very start of that internship, is there something that you would tell yourself?Write shorter code. I have a tendency to write massive, many-thousand line files that I break out of right at the end. And then half-way through a project I’m doing something, I think “Where did I write that bit that does that thing?”, and it’s almost impossible to find. I wrote some horrendous code when I started. Just that principle, just keep things short. Even if looks a bit crazy to be jumping around all over the place all of the time, it’s actually a lot more understandable.And how do you hold yourself to that?Generally, if a function’s going off my screen, it’s probably too long. That’s what I tell myself, and within the team here we have code reviews, so the guys I’m with at the moment are pretty good at pulling me up on, “Doesn’t that look like it’s getting a bit long?”. It’s more just the subjective standard of readability than anything.So you’re an advocate of code review?Yes, definitely. Both to spot errors that you might have made, and to improve your knowledge. The person you’re reviewing will say “Oh, you could have done it that way”. That’s how we learn, by talking to others, and also just sharing knowledge of how your project works around the team, or even outside the team. Definitely a very firm advocate of code reviews.Do you think there’s more we could do with them?I don’t know. We’re struggling with how to add them as part of the process without it becoming too cumbersome. We’ve experimented with a few different ways, and we’ve not found anything that just works.To get more into the nitty gritty: how do you like to debug code?The first thing is to do it in my head. I’ll actually think what piece of code is likely to have caused that error, and take a quick look at it, just to see if there’s anything glaringly obvious there. The next thing I’ll probably do is throw in print statements, or throw some exceptions from various points, just to check: is it going through the code path I expect it to? A last resort is to actually debug code using a debugger.Why is the debugger the last resort?Probably because of the environments I learnt programming in. VB and early BASIC didn’t have much of a debugger, the only way to find out what your program was doing was to add print statements. Also, because a lot of the stuff I tend to work with is non-interactive, if it’s something that takes a long time to run, I can throw in the print statements, set a run off, go and do something else, and look at it again later, rather than trying to remember what happened at that point when I was debugging through it. So it also gives me the record of what happens. I hate just sitting there pressing F5, F5, continually. If you’re having to find out what your code is doing at each line, you’ve probably got a very wrong mental model of what your code’s doing, and you can find that out just as easily by inspecting a couple of values through the print statements.If I were on some codebase that you were also working on, what should I do to make it as easy as possible to understand?I’d say short and well-named methods. The one thing I like to do when I’m looking at code is to find out where a value comes from, and the more layers of indirection there are, particularly DI [dependency injection] frameworks, the harder it is to find out where something’s come from. I really hate that. I want to know if the value come from the user here or is a constant here, and if I can’t find that out, that makes code very hard to understand for me.As a tester, where do you think the split should lie between software engineers and testers?I think the split is less on areas of the code you write and more what you’re designing and creating. The developers put a structure on the code, while my major role is to say which tests we should have, whether we should test that, or it’s not worth testing that because it’s a tiny function in code that nobody’s ever actually going to see. So it’s not a split in the code, it’s a split in what you’re thinking about. Saying what code we should write, but alternatively what code we should take out.In your experience, do the software engineers tend to do much testing themselves?They tend to control the lowest layer of tests. And, depending on how the balance of people is in the team, they might write some of the higher levels of test. Or that might go to the testers. I’m the only tester on my team with three other developers, so they’ll be writing quite a lot of the actual test code, with input from me as to whether we should test that functionality, whereas on other teams, where it’s been more equal numbers, the testers have written pretty much all of the high level tests, just because that’s the best use of resource.If you could shuffle resources around however you liked, do you think that the developers should be writing those high-level tests?I think they should be writing them occasionally. It helps when they have an understanding of how testing code works and possibly what assumptions we’ve made in tests, and they can say “actually, it doesn’t work like that under the hood so you’ve missed this whole area”. It’s one of those agile things that everyone on the team should be at least comfortable doing the various jobs. So if the developers can write test code then I think that’s a very good thing.So you think testers should be able to write production code?Yes, although given most testers skills at coding, I wouldn’t advise it too much! I have written a few things, and I did make a few changes that have actually gone into our production code base. They’re not necessarily running every time but they are there. I think having that mix of skill sets is really useful. In some ways we’re using our own product to test itself, so being able to make those changes where it’s not working saves me a round-trip through the developers. It can be really annoying if the developers have no time to make a change, and I can’t touch the code.If the software engineers are consistently writing tests at all levels, what role do you think the role of a tester is?I think on a team like that, those distinctions aren’t quite so useful. There’ll be two cases. There’s either the case where the developers think they’ve written good tests, but you still need someone with a test engineer mind-set to go through the tests and validate that it’s a useful set, or the correct set for that code. Or they won’t actually be pure developers, they’ll have that mix of test ability in there.I think having slightly more distinct roles is useful. When it starts to blur, then you lose that view of the tests as a whole. The tester job is not to create tests, it’s to validate the quality of the product, and you don’t do that just by writing tests. There’s more things you’ve got to keep in your mind. And I think when you blur the roles, you start to lose that end of the tester.So because you’re working on those features, you lose that holistic view of the whole system?Yeah, and anyone who’s worked on the feature shouldn’t be testing it. You always need to have it tested it by someone who didn’t write it. Otherwise you’re a bit too close and you assume “yes, people will only use it that way”, but the tester will come along and go “how do people use this? How would our most idiotic user use this?”. I might not test that because it might be completely irrelevant. But it’s coming in and trying to have a different set of assumptions.Are you a believer that it should all be automated if possible?Not entirely. So an automated test is always better than a manual test for the long-term, but there’s still nothing that beats a human sitting in front of the application and thinking “What could I do at this point?”. The automated test is very good but they follow that strict path, and they never check anything off the path. The human tester will look at things that they weren’t expecting, whereas the automated test can only ever go “Is that value correct?” in many respects, and it won’t notice that on the other side of the screen you’re showing something completely wrong. And that value might have been checked independently, but you always find a few odd interactions when you’re going through something manually, and you always need to go through something manually to start with anyway, otherwise you won’t know where the important bits to write your automation are.When you’re doing that manual testing, do you think it’s important to do that across the entire product, or just the bits that you’ve touched recently?I think it’s important to do it mostly on the bits you’ve touched, but you can’t ignore the rest of the product. Unless you’re dealing with a very, very self-contained bit, you’re almost always encounter other bits of the product along the way. Most testers I know, even if they are looking at just one path, they’ll keep open and move around a bit anyway, just because they want to find something that’s broken. If we find that your path is right, we’ll go out and hunt something else.How do you think this fits into the idea of continuously deploying, so long as the tests pass?With deploying a website it’s a bit different because you can always pull it back. If you’re deploying an application to customers, when you’ve released it, it’s out there, you can’t pull it back. Someone’s going to keep it, no matter how hard you try there will be a few installations that stay around. So I’d always have at least a human element on that path. With websites, you could probably automate straight out, or at least straight out to an internal environment or a single server in a cloud of fifty that will serve some people. But I don’t think you should release to everyone just on automated tests passing.You’ve already mentioned using BASIC and C# — are there any other languages that you’ve used?I’ve used a few. That’s something that has changed more recently, I’ve become familiar with more languages. Before I started at Red Gate I learnt a bit of C. Then last year, I taught myself Python which I actually really enjoyed using. I’ve also come across another language called Vala, which is sort of a C#-like language. It’s basically a pre-processor for C, but it has very nice syntax. I think that’s currently my favourite language.Any particular reason for trying Vala?I have a completely Linux environment at home, and I’ve been looking for a nice language, and C# just doesn’t cut it because I won’t touch Mono. So, I was looking for something like C# but that was useable in an open source environment, and Vala’s what I found. C#’s got a few features that Vala doesn’t, and Vala’s got a few features where I think “It would be awesome if C# had that”.What are some of the features that it’s missing?Extension methods. And I think that’s the only one that really bugs me. I like to use them when I’m writing C# because it makes some things really easy, especially with libraries that you can’t touch the internals of. It doesn’t have method overloading, which is sometimes annoying.Where it does win over C#?Everything is non-nullable by default, you never have to check that something’s unexpectedly null.Also, Vala has code contracts. This is starting to come in C# 4, but the way it works in Vala is that you specify requirements in short phrases as part of your function signature and they stick to the signature, so that when you inherit it, it has exactly the same code contract as the base one, or when you inherit from an interface, you have to match the signature exactly. Just using those makes you think a bit more about how you’re writing your method, it’s not an afterthought when you’ve got contracts from base classes given to you, you can’t change it. Which I think is a lot nicer than the way C# handles it. When are those actually checked?They’re checked both at compile and run-time. The compile-time checking isn’t very strong yet, it’s quite a new feature in the compiler, and because it compiles down to C, you can write C code and interface with your methods, so you can bypass that compile-time check anyway. So there’s an extra runtime check, and if you violate one of the contracts at runtime, it’s game over for your program, there’s no exception to catch, it’s just goodbye!One thing I dislike about C# is the exceptions. You write a bit of code and fifty exceptions could come from any point in your ten lines, and you can’t mentally model how those exceptions are going to come out, and you can’t even predict them based on the functions you’re calling, because if you’ve accidentally got a derived class there instead of a base class, that can throw a completely different set of exceptions. So I’ve got no way of mentally modelling those, whereas in Vala they’re checked like Java, so you know only these exceptions can come out. You know in advance the error conditions.I think Raymond Chen on Old New Thing says “the only thing you know when you throw an exception is that you’re in an invalid state somewhere in your program, so just kill it and be done with it!”You said you’ve also learnt bits of Python. How did you find that compared to Vala and C#?Very different because of the dynamic typing. I’ve been writing a website for my own use. I’m quite into photography, so I take photos off my camera, post-process them, dump them in a file, and I get a webpage with all my thumbnails. So sort of like Picassa, but written by myself because I wanted something to learn Python with. There are some things that are really nice, I just found it really difficult to cope with the fact that I’m not quite sure what this object type that I’m passed is, I might not ever be sure, so it can randomly blow up on me. But once I train myself to ignore that and just say “well, I’m fairly sure it’s going to be something that looks like this, so I’ll use it like this”, then it’s quite nice.Any particular features that you’ve appreciated?I don’t like any particular feature, it’s just very straightforward to work with. It’s very quick to write something in, particularly as you don’t have to worry that you’ve changed something that affects a different part of the program. If you have, then that part blows up, but I can get this part working right now.If you were doing a big project, would you be willing to do it in Python rather than C# or Vala?I think I might be willing to try something bigger or long term with Python. We’re currently doing an ASP.NET MVC project on C#, and I don’t like the amount of reflection. There’s a lot of magic that pulls values out, and it’s all done under the scenes. It’s almost managed to put a dynamic type system on top of C#, which in many ways destroys the language to me, whereas if you’re already in a dynamic language, having things done dynamically is much more natural. In many ways, you get the worst of both worlds. I think for web projects, I would go with Python again, whereas for anything desktop, command-line or GUI-based, I’d probably go for C# or Vala, depending on what environment I’m in.It’s the fact that you can gain from the strong typing in ways that you can’t so much on the web app. Or, in a web app, you have to use dynamic typing at some point, or you have to write a hell of a lot of boilerplate, and I’d rather use the dynamic typing than write the boilerplate.What do you think separates great programmers from everyone else?Probably design choices. Choosing to write it a piece of code one way or another. For any given program you ask me to write, I could probably do it five thousand ways. A programmer who is capable will see four or five of them, and choose one of the better ones. The excellent programmer will see the largest proportion and manage to pick the best one very quickly without having to think too much about it. I think that’s probably what separates, is the speed at which they can see what’s the best path to write the program in. More Red Gater Coder interviews

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  • ASP.NET Frameworks and Raw Throughput Performance

    - by Rick Strahl
    A few days ago I had a curious thought: With all these different technologies that the ASP.NET stack has to offer, what's the most efficient technology overall to return data for a server request? When I started this it was mere curiosity rather than a real practical need or result. Different tools are used for different problems and so performance differences are to be expected. But still I was curious to see how the various technologies performed relative to each just for raw throughput of the request getting to the endpoint and back out to the client with as little processing in the actual endpoint logic as possible (aka Hello World!). I want to clarify that this is merely an informal test for my own curiosity and I'm sharing the results and process here because I thought it was interesting. It's been a long while since I've done any sort of perf testing on ASP.NET, mainly because I've not had extremely heavy load requirements and because overall ASP.NET performs very well even for fairly high loads so that often it's not that critical to test load performance. This post is not meant to make a point  or even come to a conclusion which tech is better, but just to act as a reference to help understand some of the differences in perf and give a starting point to play around with this yourself. I've included the code for this simple project, so you can play with it and maybe add a few additional tests for different things if you like. Source Code on GitHub I looked at this data for these technologies: ASP.NET Web API ASP.NET MVC WebForms ASP.NET WebPages ASMX AJAX Services  (couldn't get AJAX/JSON to run on IIS8 ) WCF Rest Raw ASP.NET HttpHandlers It's quite a mixed bag, of course and the technologies target different types of development. What started out as mere curiosity turned into a bit of a head scratcher as the results were sometimes surprising. What I describe here is more to satisfy my curiosity more than anything and I thought it interesting enough to discuss on the blog :-) First test: Raw Throughput The first thing I did is test raw throughput for the various technologies. This is the least practical test of course since you're unlikely to ever create the equivalent of a 'Hello World' request in a real life application. The idea here is to measure how much time a 'NOP' request takes to return data to the client. So for this request I create the simplest Hello World request that I could come up for each tech. Http Handler The first is the lowest level approach which is an HTTP handler. public class Handler : IHttpHandler { public void ProcessRequest(HttpContext context) { context.Response.ContentType = "text/plain"; context.Response.Write("Hello World. Time is: " + DateTime.Now.ToString()); } public bool IsReusable { get { return true; } } } WebForms Next I added a couple of ASPX pages - one using CodeBehind and one using only a markup page. The CodeBehind page simple does this in CodeBehind without any markup in the ASPX page: public partial class HelloWorld_CodeBehind : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Response.Write("Hello World. Time is: " + DateTime.Now.ToString() ); Response.End(); } } while the Markup page only contains some static output via an expression:<%@ Page Language="C#" AutoEventWireup="false" CodeBehind="HelloWorld_Markup.aspx.cs" Inherits="AspNetFrameworksPerformance.HelloWorld_Markup" %> Hello World. Time is <%= DateTime.Now %> ASP.NET WebPages WebPages is the freestanding Razor implementation of ASP.NET. Here's the simple HelloWorld.cshtml page:Hello World @DateTime.Now WCF REST WCF REST was the token REST implementation for ASP.NET before WebAPI and the inbetween step from ASP.NET AJAX. I'd like to forget that this technology was ever considered for production use, but I'll include it here. Here's an OperationContract class: [ServiceContract(Namespace = "")] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class WcfService { [OperationContract] [WebGet] public Stream HelloWorld() { var data = Encoding.Unicode.GetBytes("Hello World" + DateTime.Now.ToString()); var ms = new MemoryStream(data); // Add your operation implementation here return ms; } } WCF REST can return arbitrary results by returning a Stream object and a content type. The code above turns the string result into a stream and returns that back to the client. ASP.NET AJAX (ASMX Services) I also wanted to test ASP.NET AJAX services because prior to WebAPI this is probably still the most widely used AJAX technology for the ASP.NET stack today. Unfortunately I was completely unable to get this running on my Windows 8 machine. Visual Studio 2012  removed adding of ASP.NET AJAX services, and when I tried to manually add the service and configure the script handler references it simply did not work - I always got a SOAP response for GET and POST operations. No matter what I tried I always ended up getting XML results even when explicitly adding the ScriptHandler. So, I didn't test this (but the code is there - you might be able to test this on a Windows 7 box). ASP.NET MVC Next up is probably the most popular ASP.NET technology at the moment: MVC. Here's the small controller: public class MvcPerformanceController : Controller { public ActionResult Index() { return View(); } public ActionResult HelloWorldCode() { return new ContentResult() { Content = "Hello World. Time is: " + DateTime.Now.ToString() }; } } ASP.NET WebAPI Next up is WebAPI which looks kind of similar to MVC. Except here I have to use a StringContent result to return the response: public class WebApiPerformanceController : ApiController { [HttpGet] public HttpResponseMessage HelloWorldCode() { return new HttpResponseMessage() { Content = new StringContent("Hello World. Time is: " + DateTime.Now.ToString(), Encoding.UTF8, "text/plain") }; } } Testing Take a minute to think about each of the technologies… and take a guess which you think is most efficient in raw throughput. The fastest should be pretty obvious, but the others - maybe not so much. The testing I did is pretty informal since it was mainly to satisfy my curiosity - here's how I did this: I used Apache Bench (ab.exe) from a full Apache HTTP installation to run and log the test results of hitting the server. ab.exe is a small executable that lets you hit a URL repeatedly and provides counter information about the number of requests, requests per second etc. ab.exe and the batch file are located in the \LoadTests folder of the project. An ab.exe command line  looks like this: ab.exe -n100000 -c20 http://localhost/aspnetperf/api/HelloWorld which hits the specified URL 100,000 times with a load factor of 20 concurrent requests. This results in output like this:   It's a great way to get a quick and dirty performance summary. Run it a few times to make sure there's not a large amount of varience. You might also want to do an IISRESET to clear the Web Server. Just make sure you do a short test run to warm up the server first - otherwise your first run is likely to be skewed downwards. ab.exe also allows you to specify headers and provide POST data and many other things if you want to get a little more fancy. Here all tests are GET requests to keep it simple. I ran each test: 100,000 iterations Load factor of 20 concurrent connections IISReset before starting A short warm up run for API and MVC to make sure startup cost is mitigated Here is the batch file I used for the test: IISRESET REM make sure you add REM C:\Program Files (x86)\Apache Software Foundation\Apache2.2\bin REM to your path so ab.exe can be found REM Warm up ab.exe -n100 -c20 http://localhost/aspnetperf/MvcPerformance/HelloWorldJsonab.exe -n100 -c20 http://localhost/aspnetperf/api/HelloWorldJson ab.exe -n100 -c20 http://localhost/AspNetPerf/WcfService.svc/HelloWorld ab.exe -n100000 -c20 http://localhost/aspnetperf/handler.ashx > handler.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/HelloWorld_CodeBehind.aspx > AspxCodeBehind.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/HelloWorld_Markup.aspx > AspxMarkup.txt ab.exe -n100000 -c20 http://localhost/AspNetPerf/WcfService.svc/HelloWorld > Wcf.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/MvcPerformance/HelloWorldCode > Mvc.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/api/HelloWorld > WebApi.txt I ran each of these tests 3 times and took the average score for Requests/second, with the machine otherwise idle. I did see a bit of variance when running many tests but the values used here are the medians. Part of this has to do with the fact I ran the tests on my local machine - result would probably more consistent running the load test on a separate machine hitting across the network. I ran these tests locally on my laptop which is a Dell XPS with quad core Sandibridge I7-2720QM @ 2.20ghz and a fast SSD drive on Windows 8. CPU load during tests ran to about 70% max across all 4 cores (IOW, it wasn't overloading the machine). Ideally you can try running these tests on a separate machine hitting the local machine. If I remember correctly IIS 7 and 8 on client OSs don't throttle so the performance here should be Results Ok, let's cut straight to the chase. Below are the results from the tests… It's not surprising that the handler was fastest. But it was a bit surprising to me that the next fastest was WebForms and especially Web Forms with markup over a CodeBehind page. WebPages also fared fairly well. MVC and WebAPI are a little slower and the slowest by far is WCF REST (which again I find surprising). As mentioned at the start the raw throughput tests are not overly practical as they don't test scripting performance for the HTML generation engines or serialization performances of the data engines. All it really does is give you an idea of the raw throughput for the technology from time of request to reaching the endpoint and returning minimal text data back to the client which indicates full round trip performance. But it's still interesting to see that Web Forms performs better in throughput than either MVC, WebAPI or WebPages. It'd be interesting to try this with a few pages that actually have some parsing logic on it, but that's beyond the scope of this throughput test. But what's also amazing about this test is the sheer amount of traffic that a laptop computer is handling. Even the slowest tech managed 5700 requests a second, which is one hell of a lot of requests if you extrapolate that out over a 24 hour period. Remember these are not static pages, but dynamic requests that are being served. Another test - JSON Data Service Results The second test I used a JSON result from several of the technologies. I didn't bother running WebForms and WebPages through this test since that doesn't make a ton of sense to return data from the them (OTOH, returning text from the APIs didn't make a ton of sense either :-) In these tests I have a small Person class that gets serialized and then returned to the client. The Person class looks like this: public class Person { public Person() { Id = 10; Name = "Rick"; Entered = DateTime.Now; } public int Id { get; set; } public string Name { get; set; } public DateTime Entered { get; set; } } Here are the updated handler classes that use Person: Handler public class Handler : IHttpHandler { public void ProcessRequest(HttpContext context) { var action = context.Request.QueryString["action"]; if (action == "json") JsonRequest(context); else TextRequest(context); } public void TextRequest(HttpContext context) { context.Response.ContentType = "text/plain"; context.Response.Write("Hello World. Time is: " + DateTime.Now.ToString()); } public void JsonRequest(HttpContext context) { var json = JsonConvert.SerializeObject(new Person(), Formatting.None); context.Response.ContentType = "application/json"; context.Response.Write(json); } public bool IsReusable { get { return true; } } } This code adds a little logic to check for a action query string and route the request to an optional JSON result method. To generate JSON, I'm using the same JSON.NET serializer (JsonConvert.SerializeObject) used in Web API to create the JSON response. WCF REST   [ServiceContract(Namespace = "")] [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)] public class WcfService { [OperationContract] [WebGet] public Stream HelloWorld() { var data = Encoding.Unicode.GetBytes("Hello World " + DateTime.Now.ToString()); var ms = new MemoryStream(data); // Add your operation implementation here return ms; } [OperationContract] [WebGet(ResponseFormat=WebMessageFormat.Json,BodyStyle=WebMessageBodyStyle.WrappedRequest)] public Person HelloWorldJson() { // Add your operation implementation here return new Person(); } } For WCF REST all I have to do is add a method with the Person result type.   ASP.NET MVC public class MvcPerformanceController : Controller { // // GET: /MvcPerformance/ public ActionResult Index() { return View(); } public ActionResult HelloWorldCode() { return new ContentResult() { Content = "Hello World. Time is: " + DateTime.Now.ToString() }; } public JsonResult HelloWorldJson() { return Json(new Person(), JsonRequestBehavior.AllowGet); } } For MVC all I have to do for a JSON response is return a JSON result. ASP.NET internally uses JavaScriptSerializer. ASP.NET WebAPI public class WebApiPerformanceController : ApiController { [HttpGet] public HttpResponseMessage HelloWorldCode() { return new HttpResponseMessage() { Content = new StringContent("Hello World. Time is: " + DateTime.Now.ToString(), Encoding.UTF8, "text/plain") }; } [HttpGet] public Person HelloWorldJson() { return new Person(); } [HttpGet] public HttpResponseMessage HelloWorldJson2() { var response = new HttpResponseMessage(HttpStatusCode.OK); response.Content = new ObjectContent<Person>(new Person(), GlobalConfiguration.Configuration.Formatters.JsonFormatter); return response; } } Testing and Results To run these data requests I used the following ab.exe commands:REM JSON RESPONSES ab.exe -n100000 -c20 http://localhost/aspnetperf/Handler.ashx?action=json > HandlerJson.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/MvcPerformance/HelloWorldJson > MvcJson.txt ab.exe -n100000 -c20 http://localhost/aspnetperf/api/HelloWorldJson > WebApiJson.txt ab.exe -n100000 -c20 http://localhost/AspNetPerf/WcfService.svc/HelloWorldJson > WcfJson.txt The results from this test run are a bit interesting in that the WebAPI test improved performance significantly over returning plain string content. Here are the results:   The performance for each technology drops a little bit except for WebAPI which is up quite a bit! From this test it appears that WebAPI is actually significantly better performing returning a JSON response, rather than a plain string response. Snag with Apache Benchmark and 'Length Failures' I ran into a little snag with Apache Benchmark, which was reporting failures for my Web API requests when serializing. As the graph shows performance improved significantly from with JSON results from 5580 to 6530 or so which is a 15% improvement (while all others slowed down by 3-8%). However, I was skeptical at first because the WebAPI test reports showed a bunch of errors on about 10% of the requests. Check out this report: Notice the Failed Request count. What the hey? Is WebAPI failing on roughly 10% of requests when sending JSON? Turns out: No it's not! But it took some sleuthing to figure out why it reports these failures. At first I thought that Web API was failing, and so to make sure I re-ran the test with Fiddler attached and runiisning the ab.exe test by using the -X switch: ab.exe -n100 -c10 -X localhost:8888 http://localhost/aspnetperf/api/HelloWorldJson which showed that indeed all requests where returning proper HTTP 200 results with full content. However ab.exe was reporting the errors. After some closer inspection it turned out that the dates varying in size altered the response length in dynamic output. For example: these two results: {"Id":10,"Name":"Rick","Entered":"2012-09-04T10:57:24.841926-10:00"} {"Id":10,"Name":"Rick","Entered":"2012-09-04T10:57:24.8519262-10:00"} are different in length for the number which results in 68 and 69 bytes respectively. The same URL produces different result lengths which is what ab.exe reports. I didn't notice at first bit the same is happening when running the ASHX handler with JSON.NET result since it uses the same serializer that varies the milliseconds. Moral: You can typically ignore Length failures in Apache Benchmark and when in doubt check the actual output with Fiddler. Note that the other failure values are accurate though. Another interesting Side Note: Perf drops over Time As I was running these tests repeatedly I was finding that performance steadily dropped from a startup peak to a 10-15% lower stable level. IOW, with Web API I'd start out with around 6500 req/sec and in subsequent runs it keeps dropping until it would stabalize somewhere around 5900 req/sec occasionally jumping lower. For these tests this is why I did the IIS RESET and warm up for individual tests. This is a little puzzling. Looking at Process Monitor while the test are running memory very quickly levels out as do handles and threads, on the first test run. Subsequent runs everything stays stable, but the performance starts going downwards. This applies to all the technologies - Handlers, Web Forms, MVC, Web API - curious to see if others test this and see similar results. Doing an IISRESET then resets everything and performance starts off at peak again… Summary As I stated at the outset, these were informal to satiate my curiosity not to prove that any technology is better or even faster than another. While there clearly are differences in performance the differences (other than WCF REST which was by far the slowest and the raw handler which was by far the highest) are relatively minor, so there is no need to feel that any one technology is a runaway standout in raw performance. Choosing a technology is about more than pure performance but also about the adequateness for the job and the easy of implementation. The strengths of each technology will make for any minor performance difference we see in these tests. However, to me it's important to get an occasional reality check and compare where new technologies are heading. Often times old stuff that's been optimized and designed for a time of less horse power can utterly blow the doors off newer tech and simple checks like this let you compare. Luckily we're seeing that much of the new stuff performs well even in V1.0 which is great. To me it was very interesting to see Web API perform relatively badly with plain string content, which originally led me to think that Web API might not be properly optimized just yet. For those that caught my Tweets late last week regarding WebAPI's slow responses was with String content which is in fact considerably slower. Luckily where it counts with serialized JSON and XML WebAPI actually performs better. But I do wonder what would make generic string content slower than serialized code? This stresses another point: Don't take a single test as the final gospel and don't extrapolate out from a single set of tests. Certainly Twitter can make you feel like a fool when you post something immediate that hasn't been fleshed out a little more <blush>. Egg on my face. As a result I ended up screwing around with this for a few hours today to compare different scenarios. Well worth the time… I hope you found this useful, if not for the results, maybe for the process of quickly testing a few requests for performance and charting out a comparison. Now onwards with more serious stuff… Resources Source Code on GitHub Apache HTTP Server Project (ab.exe is part of the binary distribution)© Rick Strahl, West Wind Technologies, 2005-2012Posted in ASP.NET  Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Syncing Data with a Server using Silverlight and HTTP Polling Duplex

    - by dwahlin
    Many applications have the need to stay in-sync with data provided by a service. Although web applications typically rely on standard polling techniques to check if data has changed, Silverlight provides several interesting options for keeping an application in-sync that rely on server “push” technologies. A few years back I wrote several blog posts covering different “push” technologies available in Silverlight that rely on sockets or HTTP Polling Duplex. We recently had a project that looked like it could benefit from pushing data from a server to one or more clients so I thought I’d revisit the subject and provide some updates to the original code posted. If you’ve worked with AJAX before in Web applications then you know that until browsers fully support web sockets or other duplex (bi-directional communication) technologies that it’s difficult to keep applications in-sync with a server without relying on polling. The problem with polling is that you have to check for changes on the server on a timed-basis which can often be wasteful and take up unnecessary resources. With server “push” technologies, data can be pushed from the server to the client as it changes. Once the data is received, the client can update the user interface as appropriate. Using “push” technologies allows the client to listen for changes from the data but stay 100% focused on client activities as opposed to worrying about polling and asking the server if anything has changed. Silverlight provides several options for pushing data from a server to a client including sockets, TCP bindings and HTTP Polling Duplex.  Each has its own strengths and weaknesses as far as performance and setup work with HTTP Polling Duplex arguably being the easiest to setup and get going.  In this article I’ll demonstrate how HTTP Polling Duplex can be used in Silverlight 4 applications to push data and show how you can create a WCF server that provides an HTTP Polling Duplex binding that a Silverlight client can consume.   What is HTTP Polling Duplex? Technologies that allow data to be pushed from a server to a client rely on duplex functionality. Duplex (or bi-directional) communication allows data to be passed in both directions.  A client can call a service and the server can call the client. HTTP Polling Duplex (as its name implies) allows a server to communicate with a client without forcing the client to constantly poll the server. It has the benefit of being able to run on port 80 making setup a breeze compared to the other options which require specific ports to be used and cross-domain policy files to be exposed on port 943 (as with sockets and TCP bindings). Having said that, if you’re looking for the best speed possible then sockets and TCP bindings are the way to go. But, they’re not the only game in town when it comes to duplex communication. The first time I heard about HTTP Polling Duplex (initially available in Silverlight 2) I wasn’t exactly sure how it was any better than standard polling used in AJAX applications. I read the Silverlight SDK, looked at various resources and generally found the following definition unhelpful as far as understanding the actual benefits that HTTP Polling Duplex provided: "The Silverlight client periodically polls the service on the network layer, and checks for any new messages that the service wants to send on the callback channel. The service queues all messages sent on the client callback channel and delivers them to the client when the client polls the service." Although the previous definition explained the overall process, it sounded as if standard polling was used. Fortunately, Microsoft’s Scott Guthrie provided me with a more clear definition several years back that explains the benefits provided by HTTP Polling Duplex quite well (used with his permission): "The [HTTP Polling Duplex] duplex support does use polling in the background to implement notifications – although the way it does it is different than manual polling. It initiates a network request, and then the request is effectively “put to sleep” waiting for the server to respond (it doesn’t come back immediately). The server then keeps the connection open but not active until it has something to send back (or the connection times out after 90 seconds – at which point the duplex client will connect again and wait). This way you are avoiding hitting the server repeatedly – but still get an immediate response when there is data to send." After hearing Scott’s definition the light bulb went on and it all made sense. A client makes a request to a server to check for changes, but instead of the request returning immediately, it parks itself on the server and waits for data. It’s kind of like waiting to pick up a pizza at the store. Instead of calling the store over and over to check the status, you sit in the store and wait until the pizza (the request data) is ready. Once it’s ready you take it back home (to the client). This technique provides a lot of efficiency gains over standard polling techniques even though it does use some polling of its own as a request is initially made from a client to a server. So how do you implement HTTP Polling Duplex in your Silverlight applications? Let’s take a look at the process by starting with the server. Creating an HTTP Polling Duplex WCF Service Creating a WCF service that exposes an HTTP Polling Duplex binding is straightforward as far as coding goes. Add some one way operations into an interface, create a client callback interface and you’re ready to go. The most challenging part comes into play when configuring the service to properly support the necessary binding and that’s more of a cut and paste operation once you know the configuration code to use. To create an HTTP Polling Duplex service you’ll need to expose server-side and client-side interfaces and reference the System.ServiceModel.PollingDuplex assembly (located at C:\Program Files (x86)\Microsoft SDKs\Silverlight\v4.0\Libraries\Server on my machine) in the server project. For the demo application I upgraded a basketball simulation service to support the latest polling duplex assemblies. The service simulates a simple basketball game using a Game class and pushes information about the game such as score, fouls, shots and more to the client as the game changes over time. Before jumping too far into the game push service, it’s important to discuss two interfaces used by the service to communicate in a bi-directional manner. The first is called IGameStreamService and defines the methods/operations that the client can call on the server (see Listing 1). The second is IGameStreamClient which defines the callback methods that a server can use to communicate with a client (see Listing 2).   [ServiceContract(Namespace = "Silverlight", CallbackContract = typeof(IGameStreamClient))] public interface IGameStreamService { [OperationContract(IsOneWay = true)] void GetTeamData(); } Listing 1. The IGameStreamService interface defines server operations that can be called on the server.   [ServiceContract] public interface IGameStreamClient { [OperationContract(IsOneWay = true)] void ReceiveTeamData(List<Team> teamData); [OperationContract(IsOneWay = true, AsyncPattern=true)] IAsyncResult BeginReceiveGameData(GameData gameData, AsyncCallback callback, object state); void EndReceiveGameData(IAsyncResult result); } Listing 2. The IGameStreamClient interfaces defines client operations that a server can call.   The IGameStreamService interface is decorated with the standard ServiceContract attribute but also contains a value for the CallbackContract property.  This property is used to define the interface that the client will expose (IGameStreamClient in this example) and use to receive data pushed from the service. Notice that each OperationContract attribute in both interfaces sets the IsOneWay property to true. This means that the operation can be called and passed data as appropriate, however, no data will be passed back. Instead, data will be pushed back to the client as it’s available.  Looking through the IGameStreamService interface you can see that the client can request team data whereas the IGameStreamClient interface allows team and game data to be received by the client. One interesting point about the IGameStreamClient interface is the inclusion of the AsyncPattern property on the BeginReceiveGameData operation. I initially created this operation as a standard one way operation and it worked most of the time. However, as I disconnected clients and reconnected new ones game data wasn’t being passed properly. After researching the problem more I realized that because the service could take up to 7 seconds to return game data, things were getting hung up. By setting the AsyncPattern property to true on the BeginReceivedGameData operation and providing a corresponding EndReceiveGameData operation I was able to get around this problem and get everything running properly. I’ll provide more details on the implementation of these two methods later in this post. Once the interfaces were created I moved on to the game service class. The first order of business was to create a class that implemented the IGameStreamService interface. Since the service can be used by multiple clients wanting game data I added the ServiceBehavior attribute to the class definition so that I could set its InstanceContextMode to InstanceContextMode.Single (in effect creating a Singleton service object). Listing 3 shows the game service class as well as its fields and constructor.   [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, InstanceContextMode = InstanceContextMode.Single)] public class GameStreamService : IGameStreamService { object _Key = new object(); Game _Game = null; Timer _Timer = null; Random _Random = null; Dictionary<string, IGameStreamClient> _ClientCallbacks = new Dictionary<string, IGameStreamClient>(); static AsyncCallback _ReceiveGameDataCompleted = new AsyncCallback(ReceiveGameDataCompleted); public GameStreamService() { _Game = new Game(); _Timer = new Timer { Enabled = false, Interval = 2000, AutoReset = true }; _Timer.Elapsed += new ElapsedEventHandler(_Timer_Elapsed); _Timer.Start(); _Random = new Random(); }} Listing 3. The GameStreamService implements the IGameStreamService interface which defines a callback contract that allows the service class to push data back to the client. By implementing the IGameStreamService interface, GameStreamService must supply a GetTeamData() method which is responsible for supplying information about the teams that are playing as well as individual players.  GetTeamData() also acts as a client subscription method that tracks clients wanting to receive game data.  Listing 4 shows the GetTeamData() method. public void GetTeamData() { //Get client callback channel var context = OperationContext.Current; var sessionID = context.SessionId; var currClient = context.GetCallbackChannel<IGameStreamClient>(); context.Channel.Faulted += Disconnect; context.Channel.Closed += Disconnect; IGameStreamClient client; if (!_ClientCallbacks.TryGetValue(sessionID, out client)) { lock (_Key) { _ClientCallbacks[sessionID] = currClient; } } currClient.ReceiveTeamData(_Game.GetTeamData()); //Start timer which when fired sends updated score information to client if (!_Timer.Enabled) { _Timer.Enabled = true; } } Listing 4. The GetTeamData() method subscribes a given client to the game service and returns. The key the line of code in the GetTeamData() method is the call to GetCallbackChannel<IGameStreamClient>().  This method is responsible for accessing the calling client’s callback channel. The callback channel is defined by the IGameStreamClient interface shown earlier in Listing 2 and used by the server to communicate with the client. Before passing team data back to the client, GetTeamData() grabs the client’s session ID and checks if it already exists in the _ClientCallbacks dictionary object used to track clients wanting callbacks from the server. If the client doesn’t exist it adds it into the collection. It then pushes team data from the Game class back to the client by calling ReceiveTeamData().  Since the service simulates a basketball game, a timer is then started if it’s not already enabled which is then used to randomly send data to the client. When the timer fires, game data is pushed down to the client. Listing 5 shows the _Timer_Elapsed() method that is called when the timer fires as well as the SendGameData() method used to send data to the client. void _Timer_Elapsed(object sender, ElapsedEventArgs e) { int interval = _Random.Next(3000, 7000); lock (_Key) { _Timer.Interval = interval; _Timer.Enabled = false; } SendGameData(_Game.GetGameData()); } private void SendGameData(GameData gameData) { var cbs = _ClientCallbacks.Where(cb => ((IContextChannel)cb.Value).State == CommunicationState.Opened); for (int i = 0; i < cbs.Count(); i++) { var cb = cbs.ElementAt(i).Value; try { cb.BeginReceiveGameData(gameData, _ReceiveGameDataCompleted, cb); } catch (TimeoutException texp) { //Log timeout error } catch (CommunicationException cexp) { //Log communication error } } lock (_Key) _Timer.Enabled = true; } private static void ReceiveGameDataCompleted(IAsyncResult result) { try { ((IGameStreamClient)(result.AsyncState)).EndReceiveGameData(result); } catch (CommunicationException) { // empty } catch (TimeoutException) { // empty } } LIsting 5. _Timer_Elapsed is used to simulate time in a basketball game. When _Timer_Elapsed() fires the SendGameData() method is called which iterates through the clients wanting to be notified of changes. As each client is identified, their respective BeginReceiveGameData() method is called which ultimately pushes game data down to the client. Recall that this method was defined in the client callback interface named IGameStreamClient shown earlier in Listing 2. Notice that BeginReceiveGameData() accepts _ReceiveGameDataCompleted as its second parameter (an AsyncCallback delegate defined in the service class) and passes the client callback as the third parameter. The initial version of the sample application had a standard ReceiveGameData() method in the client callback interface. However, sometimes the client callbacks would work properly and sometimes they wouldn’t which was a little baffling at first glance. After some investigation I realized that I needed to implement an asynchronous pattern for client callbacks to work properly since 3 – 7 second delays are occurring as a result of the timer. Once I added the BeginReceiveGameData() and ReceiveGameDataCompleted() methods everything worked properly since each call was handled in an asynchronous manner. The final task that had to be completed to get the server working properly with HTTP Polling Duplex was adding configuration code into web.config. In the interest of brevity I won’t post all of the code here since the sample application includes everything you need. However, Listing 6 shows the key configuration code to handle creating a custom binding named pollingDuplexBinding and associate it with the service’s endpoint.   <bindings> <customBinding> <binding name="pollingDuplexBinding"> <binaryMessageEncoding /> <pollingDuplex maxPendingSessions="2147483647" maxPendingMessagesPerSession="2147483647" inactivityTimeout="02:00:00" serverPollTimeout="00:05:00"/> <httpTransport /> </binding> </customBinding> </bindings> <services> <service name="GameService.GameStreamService" behaviorConfiguration="GameStreamServiceBehavior"> <endpoint address="" binding="customBinding" bindingConfiguration="pollingDuplexBinding" contract="GameService.IGameStreamService"/> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /> </service> </services>   Listing 6. Configuring an HTTP Polling Duplex binding in web.config and associating an endpoint with it. Calling the Service and Receiving “Pushed” Data Calling the service and handling data that is pushed from the server is a simple and straightforward process in Silverlight. Since the service is configured with a MEX endpoint and exposes a WSDL file, you can right-click on the Silverlight project and select the standard Add Service Reference item. After the web service proxy is created you may notice that the ServiceReferences.ClientConfig file only contains an empty configuration element instead of the normal configuration elements created when creating a standard WCF proxy. You can certainly update the file if you want to read from it at runtime but for the sample application I fed the service URI directly to the service proxy as shown next: var address = new EndpointAddress("http://localhost.:5661/GameStreamService.svc"); var binding = new PollingDuplexHttpBinding(); _Proxy = new GameStreamServiceClient(binding, address); _Proxy.ReceiveTeamDataReceived += _Proxy_ReceiveTeamDataReceived; _Proxy.ReceiveGameDataReceived += _Proxy_ReceiveGameDataReceived; _Proxy.GetTeamDataAsync(); This code creates the proxy and passes the endpoint address and binding to use to its constructor. It then wires the different receive events to callback methods and calls GetTeamDataAsync().  Calling GetTeamDataAsync() causes the server to store the client in the server-side dictionary collection mentioned earlier so that it can receive data that is pushed.  As the server-side timer fires and game data is pushed to the client, the user interface is updated as shown in Listing 7. Listing 8 shows the _Proxy_ReceiveGameDataReceived() method responsible for handling the data and calling UpdateGameData() to process it.   Listing 7. The Silverlight interface. Game data is pushed from the server to the client using HTTP Polling Duplex. void _Proxy_ReceiveGameDataReceived(object sender, ReceiveGameDataReceivedEventArgs e) { UpdateGameData(e.gameData); } private void UpdateGameData(GameData gameData) { //Update Score this.tbTeam1Score.Text = gameData.Team1Score.ToString(); this.tbTeam2Score.Text = gameData.Team2Score.ToString(); //Update ball visibility if (gameData.Action != ActionsEnum.Foul) { if (tbTeam1.Text == gameData.TeamOnOffense) { AnimateBall(this.BB1, this.BB2); } else //Team 2 { AnimateBall(this.BB2, this.BB1); } } if (this.lbActions.Items.Count > 9) this.lbActions.Items.Clear(); this.lbActions.Items.Add(gameData.LastAction); if (this.lbActions.Visibility == Visibility.Collapsed) this.lbActions.Visibility = Visibility.Visible; } private void AnimateBall(Image onBall, Image offBall) { this.FadeIn.Stop(); Storyboard.SetTarget(this.FadeInAnimation, onBall); Storyboard.SetTarget(this.FadeOutAnimation, offBall); this.FadeIn.Begin(); } Listing 8. As the server pushes game data, the client’s _Proxy_ReceiveGameDataReceived() method is called to process the data. In a real-life application I’d go with a ViewModel class to handle retrieving team data, setup data bindings and handle data that is pushed from the server. However, for the sample application I wanted to focus on HTTP Polling Duplex and keep things as simple as possible.   Summary Silverlight supports three options when duplex communication is required in an application including TCP bindins, sockets and HTTP Polling Duplex. In this post you’ve seen how HTTP Polling Duplex interfaces can be created and implemented on the server as well as how they can be consumed by a Silverlight client. HTTP Polling Duplex provides a nice way to “push” data from a server while still allowing the data to flow over port 80 or another port of your choice.   Sample Application Download

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  • jQueryUI Tabs: how to keep them on a single line?

    - by Andi
    Hi all, Maybe my question is wired: is there a way to prevent jQueryUI tabs from floating if browser window is too small? Explanation: I have a simple horizontal tab using CSS only. The content is floating but not the tabs. Important: there is no width set manually, the current width is taken automatically. Here is the code: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <style type="text/css"> #tabs ul { white-space: nowrap; } #tabs ul li { display: inline; white-space: nowrap; } </style> <title>Tabs-CSS</title> </head> <body> <div class="demo"> <div id="tabs"> <ul> <li><a href="#tabs-1">Preloaded</a></li> <li><a href="ajax/content1.html">Tab 1</a></li> <li><a href="ajax/content2.html">Tab 2</a></li> <li><a href="ajax/content3-slow.php">Tab 3 (slow)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> </ul> <div id="tabs-1"> <p>Proin elit arcu, rutrum commodo, vehicula tempus, commodo a, risus. Curabitur nec arcu. Donec sollicitudin mi sit amet mauris. Nam elementum quam ullamcorper ante. Etiam aliquet massa et lorem. Mauris dapibus lacus auctor risus. Aenean tempor ullamcorper leo. Vivamus sed magna quis ligula eleifend adipiscing. Duis orci. Aliquam sodales tortor vitae ipsum. Aliquam nulla. Duis aliquam molestie erat. Ut et mauris vel pede varius sollicitudin. Sed ut dolor nec orci tincidunt interdum. Phasellus ipsum. Nunc tristique tempus lectus.</p> </div> </div> </div> </body> </html> This is exactly what I want. Next step: add jQueryUI Tab as unobtrusive Javascript. For example like this: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js" type="text/javascript"></script> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.1/jquery-ui.min.js"></script> <link type="text/css" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.7.2/themes/ui-lightness/jquery-ui.css" rel="stylesheet"/> <style type="text/css"> #tabs ul { white-space: nowrap; } #tabs ul li { display: inline; white-space: nowrap; } </style> <title>Tabs-CSS</title> </head> <body> <div class="demo"> <div id="tabs"> <ul> <li><a href="#tabs-1">Preloaded</a></li> <li><a href="ajax/content1.html">Tab 1</a></li> <li><a href="ajax/content2.html">Tab 2</a></li> <li><a href="ajax/content3-slow.php">Tab 3 (slow)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> </ul> <div id="tabs-1"> <p>Proin elit arcu, rutrum commodo, vehicula tempus, commodo a, risus. Curabitur nec arcu. Donec sollicitudin mi sit amet mauris. Nam elementum quam ullamcorper ante. Etiam aliquet massa et lorem. Mauris dapibus lacus auctor risus. Aenean tempor ullamcorper leo. Vivamus sed magna quis ligula eleifend adipiscing. Duis orci. Aliquam sodales tortor vitae ipsum. Aliquam nulla. Duis aliquam molestie erat. Ut et mauris vel pede varius sollicitudin. Sed ut dolor nec orci tincidunt interdum. Phasellus ipsum. Nunc tristique tempus lectus.</p> </div> </div> </div> <script type="text/javascript"> //<![CDATA[ $(function() { $("#tabs").tabs({ ajaxOptions: { error: function(xhr, status, index, anchor) { $(anchor.hash).html("Couldn't load this tab. We'll try to fix this as soon as possible. If this wouldn't be a demo."); }, } }); }); $(function() { $("#innertabs").tabs({ ajaxOptions: { error: function(xhr, status, index, anchor) { $(anchor.hash).html("Couldn't load this tab. We'll try to fix this as soon as possible. If this wouldn't be a demo."); } } }); }); //]]> </script> </body> </html> Now I can see that the tabbar floats on minimizing the browser window. And there are some ugly effect with the tabs jumping around. My main questions is: can I avoid floating the tabbar and keep all tabs on one single line? Kind regards, Andi

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  • jQueryUI Tabs: how too keep them on a single line?

    - by Andi
    Hi all, Maybe my question is wired: is there a way to prevent jQueryUI tabs from floating if browser window is too small? Explanation: I have a simple horizontal tab using CSS only. The content is floating but not the tabs. Important: there is no width set manually, the current width is taken automatically. Here is the code: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <style type="text/css"> #tabs ul { white-space: nowrap; } #tabs ul li { display: inline; white-space: nowrap; } </style> <title>Tabs-CSS</title> </head> <body> <div class="demo"> <div id="tabs"> <ul> <li><a href="#tabs-1">Preloaded</a></li> <li><a href="ajax/content1.html">Tab 1</a></li> <li><a href="ajax/content2.html">Tab 2</a></li> <li><a href="ajax/content3-slow.php">Tab 3 (slow)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> </ul> <div id="tabs-1"> <p>Proin elit arcu, rutrum commodo, vehicula tempus, commodo a, risus. Curabitur nec arcu. Donec sollicitudin mi sit amet mauris. Nam elementum quam ullamcorper ante. Etiam aliquet massa et lorem. Mauris dapibus lacus auctor risus. Aenean tempor ullamcorper leo. Vivamus sed magna quis ligula eleifend adipiscing. Duis orci. Aliquam sodales tortor vitae ipsum. Aliquam nulla. Duis aliquam molestie erat. Ut et mauris vel pede varius sollicitudin. Sed ut dolor nec orci tincidunt interdum. Phasellus ipsum. Nunc tristique tempus lectus.</p> </div> </div> </div> </body> </html> This is exactly what I want. Next step: add jQueryUI Tab as unobtrusive Javascript. For example like this: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js" type="text/javascript"></script> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.1/jquery-ui.min.js"></script> <link type="text/css" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.7.2/themes/ui-lightness/jquery-ui.css" rel="stylesheet"/> <style type="text/css"> #tabs ul { white-space: nowrap; } #tabs ul li { display: inline; white-space: nowrap; } </style> <title>Tabs-CSS</title> </head> <body> <div class="demo"> <div id="tabs"> <ul> <li><a href="#tabs-1">Preloaded</a></li> <li><a href="ajax/content1.html">Tab 1</a></li> <li><a href="ajax/content2.html">Tab 2</a></li> <li><a href="ajax/content3-slow.php">Tab 3 (slow)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> <li><a href="ajax/content4-broken.php">Tab 4 (broken)</a></li> </ul> <div id="tabs-1"> <p>Proin elit arcu, rutrum commodo, vehicula tempus, commodo a, risus. Curabitur nec arcu. Donec sollicitudin mi sit amet mauris. Nam elementum quam ullamcorper ante. Etiam aliquet massa et lorem. Mauris dapibus lacus auctor risus. Aenean tempor ullamcorper leo. Vivamus sed magna quis ligula eleifend adipiscing. Duis orci. Aliquam sodales tortor vitae ipsum. Aliquam nulla. Duis aliquam molestie erat. Ut et mauris vel pede varius sollicitudin. Sed ut dolor nec orci tincidunt interdum. Phasellus ipsum. Nunc tristique tempus lectus.</p> </div> </div> </div> <script type="text/javascript"> //<![CDATA[ $(function() { $("#tabs").tabs({ ajaxOptions: { error: function(xhr, status, index, anchor) { $(anchor.hash).html("Couldn't load this tab. We'll try to fix this as soon as possible. If this wouldn't be a demo."); }, } }); }); $(function() { $("#innertabs").tabs({ ajaxOptions: { error: function(xhr, status, index, anchor) { $(anchor.hash).html("Couldn't load this tab. We'll try to fix this as soon as possible. If this wouldn't be a demo."); } } }); }); //]]> </script> </body> </html> Now I can see that the tabbar floats on minimizing the browser window. And there are some ugly effect with the tabs jumping around. My main questions is: can I avoid floating the tabbar and keep all tabs on one single line? Kind regards, Andi

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  • how to debug "deep" crashes in Android?

    - by eerok512
    Hi All, I've been trying to debug an android crash that is occurring without a Java Stack Trace... Java Stack Trace bugs are very easy for me to fix... but this bug I'm getting seems to be crashing inside the "NDK" or whatever it is the deep internals of Android are called... I've made no modifications to the NDK btw... I just dunno what else to call that layer hehe. Anyway I'm mainly looking for advice on deep-debug methods, rather than help with this specific problem... because I doubt I can post all the source code involved... so really I just need to know how to set breakpoints at the deep layers or whatever other methods there are to trace deep-crashes to their source... so I will briefly describe the bug and then post a LogCat. I have an app with 7 Activities Activity_INTRO Activity_EULA Activity_MAIN Activity_Contact Activity_News Activity_Library Activity_More INTRO is the initiating one... it fades in some company logos... after displaying them for a set time it jumps to the EULA activity... after the user accepts the EULA, it jumps to MAIN... MAIN then creates a TabHost and populates it with the 4 remaining activities now heres the thing... when I click on say, the More tab of the TabHost, the app pauses for a few seconds and then hard-crashes... no java stack trace, but an actual ASM level trace with the registers and IP and stack... the same thing occurs no matter which tab I select, Contact, News, Library, More... all of them crash with the same hard-crash if however I set the manifest to start the app at Activity_MAIN, bypassing the INTRO and EULA, then these crashes do not occur... so something is lingering from those opening activities that is somehow hosing the TabHost'ed Activities... and I'm wondering what the hell that could be... because I'm using finish() on those activites when they need to jump... in fact here is how I'm doing it let me know if you see any bugs: when jumping from INTRO to EULA I do: //Display the EULA Intent newIntent = new Intent (avi, Activity_EULA.class); startActivity (newIntent); finish(); and EULA to MAIN: Intent newIntent = new Intent (this, Activity_Main.class); startActivity (newIntent); finish(); anyway, here is the hard crash log... please let me know if there is some way I can reverse engineer either /system/lib/libcutils.so or /system/lib/libandroid_runtime.so, because I think the crash is happening in one of them... i think its happening in the libandroid_runtime in fact.... anyway on to the log: 12-25 00:56:07.322: INFO/DEBUG(551): *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** 12-25 00:56:07.332: INFO/DEBUG(551): Build fingerprint: 'generic/sdk/generic/:1.5/CUPCAKE/150240:eng/test-keys' 12-25 00:56:07.362: INFO/DEBUG(551): pid: 722, tid: 723 >>> com.killerapps.chokes <<< 12-25 00:56:07.362: INFO/DEBUG(551): signal 11 (SIGSEGV), fault addr 00000004 12-25 00:56:07.362: INFO/DEBUG(551): r0 00000004 r1 40021800 r2 00000004 r3 ad3296c5 12-25 00:56:07.372: INFO/DEBUG(551): r4 00000000 r5 00000000 r6 ad342da5 r7 41039fb8 12-25 00:56:07.372: INFO/DEBUG(551): r8 100ffcb0 r9 41039fb0 10 41e014a0 fp 00001071 12-25 00:56:07.382: INFO/DEBUG(551): ip ad35b874 sp 100ffc98 lr ad3296cf pc afb045a8 cpsr 00000010 12-25 00:56:07.552: INFO/DEBUG(551): #00 pc 000045a8 /system/lib/libcutils.so 12-25 00:56:07.572: INFO/DEBUG(551): #01 lr ad3296cf /system/lib/libandroid_runtime.so 12-25 00:56:07.582: INFO/DEBUG(551): stack: 12-25 00:56:07.582: INFO/DEBUG(551): 100ffc58 00000000 12-25 00:56:07.592: INFO/DEBUG(551): 100ffc5c 001c5278 [heap] 12-25 00:56:07.602: INFO/DEBUG(551): 100ffc60 000000da 12-25 00:56:07.602: INFO/DEBUG(551): 100ffc64 0016c778 [heap] 12-25 00:56:07.602: INFO/DEBUG(551): 100ffc68 100ffcc8 12-25 00:56:07.602: INFO/DEBUG(551): 100ffc6c 001c5278 [heap] 12-25 00:56:07.612: INFO/DEBUG(551): 100ffc70 427d1ac0 12-25 00:56:07.612: INFO/DEBUG(551): 100ffc74 000000c1 12-25 00:56:07.612: INFO/DEBUG(551): 100ffc78 40021800 12-25 00:56:07.612: INFO/DEBUG(551): 100ffc7c 000000c2 12-25 00:56:07.612: INFO/DEBUG(551): 100ffc80 00000000 12-25 00:56:07.612: INFO/DEBUG(551): 100ffc84 00000000 12-25 00:56:07.622: INFO/DEBUG(551): 100ffc88 00000000 12-25 00:56:07.622: INFO/DEBUG(551): 100ffc8c 00000000 12-25 00:56:07.622: INFO/DEBUG(551): 100ffc90 df002777 12-25 00:56:07.632: INFO/DEBUG(551): 100ffc94 e3a070ad 12-25 00:56:07.632: INFO/DEBUG(551): #00 100ffc98 00000000 12-25 00:56:07.632: INFO/DEBUG(551): 100ffc9c ad3296cf /system/lib/libandroid_runtime.so 12-25 00:56:07.632: INFO/DEBUG(551): 100ffca0 100ffcd0 12-25 00:56:07.642: INFO/DEBUG(551): 100ffca4 ad342db5 /system/lib/libandroid_runtime.so 12-25 00:56:07.642: INFO/DEBUG(551): 100ffca8 410a79d0 12-25 00:56:07.642: INFO/DEBUG(551): 100ffcac ad00e3b8 /system/lib/libdvm.so 12-25 00:56:07.652: INFO/DEBUG(551): 100ffcb0 410a79d0 12-25 00:56:07.652: INFO/DEBUG(551): 100ffcb4 0016bac0 [heap] 12-25 00:56:07.662: INFO/DEBUG(551): 100ffcb8 ad342da5 /system/lib/libandroid_runtime.so 12-25 00:56:07.662: INFO/DEBUG(551): 100ffcbc 40021800 12-25 00:56:07.662: INFO/DEBUG(551): 100ffcc0 410a79d0 12-25 00:56:07.662: INFO/DEBUG(551): 100ffcc4 afe39dd0 12-25 00:56:07.662: INFO/DEBUG(551): 100ffcc8 100ffcd0 12-25 00:56:07.662: INFO/DEBUG(551): 100ffccc ad040a8d /system/lib/libdvm.so 12-25 00:56:07.672: INFO/DEBUG(551): 100ffcd0 41039fb0 12-25 00:56:07.672: INFO/DEBUG(551): 100ffcd4 420000f8 12-25 00:56:07.672: INFO/DEBUG(551): 100ffcd8 ad342da5 /system/lib/libandroid_runtime.so 12-25 00:56:07.672: INFO/DEBUG(551): 100ffcdc 100ffd48 12-25 00:56:07.852: DEBUG/dalvikvm(722): GC freed 367 objects / 15144 bytes in 210ms 12-25 00:56:08.081: DEBUG/InetAddress(722): www.akillerapp.com: 74.86.47.202 (family 2, proto 6) 12-25 00:56:08.242: DEBUG/dalvikvm(722): GC freed 62 objects / 2328 bytes in 122ms 12-25 00:56:08.771: DEBUG/dalvikvm(722): GC freed 245 objects / 11744 bytes in 179ms 12-25 00:56:09.131: INFO/ActivityManager(577): Process com.killerapps.chokes (pid 722) has died. 12-25 00:56:09.171: INFO/WindowManager(577): WIN DEATH: Window{43719320 com.killerapps.chokes/com.killerapps.chokes.Activity_Main paused=false} 12-25 00:56:09.251: INFO/DEBUG(551): debuggerd committing suicide to free the zombie! 12-25 00:56:09.291: DEBUG/Zygote(553): Process 722 terminated by signal (11) 12-25 00:56:09.311: INFO/DEBUG(781): debuggerd: Jun 30 2009 17:00:51 12-25 00:56:09.331: WARN/InputManagerService(577): Got RemoteException sending setActive(false) notification to pid 722 uid 10020

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