form load - Page 228 - Developer IT

i need to load view using .xib when button pressed (without using view controller for this xib)

- by ven

i am having a existing view controller which having buttons ,when one of this button gets pressed iwaant to load a view to load to display text

How would one dynamically load Javascript that has been parsed as PHP?

I am looking to dynamically load javascript that has been parsed as PHP so that I will be able to pass PHP variables to javascript, and then load this file into the primary PHP document. I have a document called myscript.js.php that includes the javascript and PHP. I attempted to load it into the primary document using jQuery's getScript like this: $.getScript("myscript.js.php", function() { alert('loaded script.'); }); This attempt failed - I am assuming because of the .php extension on the file. Is there anyway to dynamically load javascript that includes PHP? I have a few session variables that I am looking to pass through javascript that will be updated frequently, creating a need for the javascript to be reloaded.

Read the article

Loading jQuery Consistently in a .NET Web App

- by Rick Strahl

One thing that frequently comes up in discussions when using jQuery is how to best load the jQuery library (as well as other commonly used and updated libraries) in a Web application. Specifically the issue is the one of versioning and making sure that you can easily update and switch versions of script files with application wide settings in one place and having your script usage reflect those settings in the entire application on all pages that use the script. Although I use jQuery as an example here, the same concepts can be applied to any script library - for example in my Web libraries I use the same approach for jQuery.ui and my own internal jQuery support library. The concepts used here can be applied both in WebForms and MVC. Loading jQuery Properly From CDN Before we look at a generic way to load jQuery via some server logic, let me first point out my preferred way to embed jQuery into the page. I use the Google CDN to load jQuery and then use a fallback URL to handle the offline or no Internet connection scenario. Why use a CDN? CDN links tend to be loaded more quickly since they are very likely to be cached in user's browsers already as jQuery CDN is used by many, many sites on the Web. Using a CDN also removes load from your Web server and puts the load bearing on the CDN provider - in this case Google - rather than on your Web site. On the downside, CDN links gives the provider (Google, Microsoft) yet another way to track users through their Web usage. Here's how I use jQuery CDN plus a fallback link on my WebLog for example: <!DOCTYPE HTML> <html> <head> <script src="//ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js"></script> <script> if (typeof (jQuery) == 'undefined') document.write(unescape("%3Cscript " + "src='/Weblog/wwSC.axd?r=Westwind.Web.Controls.Resources.jquery.js' %3E%3C/script%3E")); </script> <title>Rick Strahl's Web Log</title> ... </head> You can see that the CDN is referenced first, followed by a small script block that checks to see whether jQuery was loaded (jQuery object exists). If it didn't load another script reference is added to the document dynamically pointing to a backup URL. In this case my backup URL points at a WebResource in my Westwind.Web assembly, but the URL can also be local script like src="/scripts/jquery.min.js". Important: Use the proper Protocol/Scheme for for CDN Urls [updated based on comments] If you're using a CDN to load an external script resource you should always make sure that the script is loaded with the same protocol as the parent page to avoid mixed content warnings by the browser. You don't want to load a script link to an http:// resource when you're on an https:// page. The easiest way to use this is by using a protocol relative URL: <script src="//ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js"></script> which is an easy way to load resources from other domains. This URL syntax will automatically use the parent page's protocol (or more correctly scheme). As long as the remote domains support both http:// and https:// access this should work. BTW this also works in CSS (with some limitations) and links. BTW, I didn't know about this until it was pointed out in the comments. This is a very useful feature for many things - ah the benefits of my blog to myself :-) Version Numbers When you use a CDN you notice that you have to reference a specific version of jQuery. When using local files you may not have to do this as you can rename your private copy of jQuery.js, but for CDN the references are always versioned. The version number is of course very important to ensure you getting the version you have tested with, but it's also important to the provider because it ensures that cached content is always correct. If an existing file was updated the updates might take a very long time to get past the locally cached content and won't refresh properly. The version number ensures you get the right version and not some cached content that has been changed but not updated in your cache. On the other hand version numbers also mean that once you decide to use a new version of the script you now have to change all your script references in your pages. Depending on whether you use some sort of master/layout page or not this may or may not be easy in your application. Even if you do use master/layout pages, chances are that you probably have a few of them and at the very least all of those have to be updated for the scripts. If you use individual pages for all content this issue then spreads to all of your pages. Search and Replace in Files will do the trick, but it's still something that's easy to forget and worry about. Personaly I think it makes sense to have a single place where you can specify common script libraries that you want to load and more importantly which versions thereof and where they are loaded from. Loading Scripts via Server Code Script loading has always been important to me and as long as I can remember I've always built some custom script loading routines into my Web frameworks. WebForms makes this fairly easy because it has a reasonably useful script manager (ClientScriptManager and the ScriptManager) which allow injecting script into the page easily from anywhere in the Page cycle. What's nice about these components is that they allow scripts to be injected by controls so components can wrap up complex script/resource dependencies more easily without having to require long lists of CSS/Scripts/Image includes. In MVC or pure script driven applications like Razor WebPages the process is more raw, requiring you to embed script references in the right place. But its also more immediate - it lets you know exactly which versions of scripts to use because you have to manually embed them. In WebForms with different controls loading resources this often can get confusing because it's quite possible to load multiple versions of the same script library into a page, the results of which are less than optimal… In this post I look a simple routine that embeds jQuery into the page based on a few application wide configuration settings. It returns only a string of the script tags that can be manually embedded into a Page template. It's a small function that merely a string of the script tags shown at the begging of this post along with some options on how that string is comprised. You'll be able to specify in one place which version loads and then all places where the help function is used will automatically reflect this selection. Options allow specification of the jQuery CDN Url, the fallback Url and where jQuery should be loaded from (script folder, Resource or CDN in my case). While this is specific to jQuery you can apply this to other resources as well. For example I use a similar approach with jQuery.ui as well using practically the same semantics. Providing Resources in ControlResources In my Westwind.Web Web utility library I have a class called ControlResources which is responsible for holding resource Urls, resource IDs and string contants that reference those resource IDs. The library also provides a few helper methods for loading common scriptscripts into a Web page. There are specific versions for WebForms which use the ClientScriptManager/ScriptManager and script link methods that can be used in any .NET technology that can embed an expression into the output template (or code for that matter). The ControlResources class contains mostly static content - references to resources mostly. But it also contains a few static properties that configure script loading: A Script LoadMode (CDN, Resource, or script url) A default CDN Url A fallback url They are static properties in the ControlResources class: public class ControlResources { /// <summary> /// Determines what location jQuery is loaded from /// </summary> public static JQueryLoadModes jQueryLoadMode = JQueryLoadModes.ContentDeliveryNetwork; /// <summary> /// jQuery CDN Url on Google /// </summary> public static string jQueryCdnUrl = "//ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js"; /// <summary> /// jQuery CDN Url on Google /// </summary> public static string jQueryUiCdnUrl = "//ajax.googleapis.com/ajax/libs/jqueryui/1.8.16/jquery-ui.min.js"; /// <summary> /// jQuery UI fallback Url if CDN is unavailable or WebResource is used /// Note: The file needs to exist and hold the minimized version of jQuery ui /// </summary> public static string jQueryUiLocalFallbackUrl = "~/scripts/jquery-ui.min.js"; } These static properties are fixed values that can be changed at application startup to reflect your preferences. Since they're static they are application wide settings and respected across the entire Web application running. It's best to set these default in Application_Init or similar startup code if you need to change them for your application: protected void Application_Start(object sender, EventArgs e) { // Force jQuery to be loaded off Google Content Network ControlResources.jQueryLoadMode = JQueryLoadModes.ContentDeliveryNetwork; // Allow overriding of the Cdn url ControlResources.jQueryCdnUrl = "http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js"; // Route to our own internal handler App.OnApplicationStart(); } With these basic settings in place you can then embed expressions into a page easily. In WebForms use: <!DOCTYPE html> <html> <head runat="server"> <%= ControlResources.jQueryLink() %> <script src="scripts/ww.jquery.min.js"></script> </head> In Razor use: <!DOCTYPE html> <html> <head> @Html.Raw(ControlResources.jQueryLink()) <script src="scripts/ww.jquery.min.js"></script> </head> Note that in Razor you need to use @Html.Raw() to force the string NOT to escape. Razor by default escapes string results and this ensures that the HTML content is properly expanded as raw HTML text. Both the WebForms and Razor output produce: <!DOCTYPE html> <html> <head> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js" type="text/javascript"></script> <script type="text/javascript"> if (typeof (jQuery) == 'undefined') document.write(unescape("%3Cscript src='/WestWindWebToolkitWeb/WebResource.axd?d=-b6oWzgbpGb8uTaHDrCMv59VSmGhilZP5_T_B8anpGx7X-PmW_1eu1KoHDvox-XHqA1EEb-Tl2YAP3bBeebGN65tv-7-yAimtG4ZnoWH633pExpJor8Qp1aKbk-KQWSoNfRC7rQJHXVP4tC0reYzVw2&t=634535391996872492' type='text/javascript'%3E%3C/script%3E"));</script> <script src="scripts/ww.jquery.min.js"></script> </head> which produces the desired effect for both CDN load and fallback URL. The implementation of jQueryLink is pretty basic of course: /// <summary> /// Inserts a script link to load jQuery into the page based on the jQueryLoadModes settings /// of this class. Default load is by CDN plus WebResource fallback /// </summary> /// <param name="url"> /// An optional explicit URL to load jQuery from. Url is resolved. /// When specified no fallback is applied /// </param> /// <returns>full script tag and fallback script for jQuery to load</returns> public static string jQueryLink(JQueryLoadModes jQueryLoadMode = JQueryLoadModes.Default, string url = null) { string jQueryUrl = string.Empty; string fallbackScript = string.Empty; if (jQueryLoadMode == JQueryLoadModes.Default) jQueryLoadMode = ControlResources.jQueryLoadMode; if (!string.IsNullOrEmpty(url)) jQueryUrl = WebUtils.ResolveUrl(url); else if (jQueryLoadMode == JQueryLoadModes.WebResource) { Page page = new Page(); jQueryUrl = page.ClientScript.GetWebResourceUrl(typeof(ControlResources), ControlResources.JQUERY_SCRIPT_RESOURCE); } else if (jQueryLoadMode == JQueryLoadModes.ContentDeliveryNetwork) { jQueryUrl = ControlResources.jQueryCdnUrl; if (!string.IsNullOrEmpty(jQueryCdnUrl)) { // check if jquery loaded - if it didn't we're not online and use WebResource fallbackScript = @"<script type=""text/javascript"">if (typeof(jQuery) == 'undefined') document.write(unescape(""%3Cscript src='{0}' type='text/javascript'%3E%3C/script%3E""));</script>"; fallbackScript = string.Format(fallbackScript, WebUtils.ResolveUrl(ControlResources.jQueryCdnFallbackUrl)); } } string output = "<script src=\"" + jQueryUrl + "\" type=\"text/javascript\"></script>"; // add in the CDN fallback script code if (!string.IsNullOrEmpty(fallbackScript)) output += "\r\n" + fallbackScript + "\r\n"; return output; } There's one dependency here on WebUtils.ResolveUrl() which resolves Urls without access to a Page/Control (another one of those features that should be in the runtime, not in the WebForms or MVC engine). You can see there's only a little bit of logic in this code that deals with potentially different load modes. I can load scripts from a Url, WebResources or - my preferred way - from CDN. Based on the static settings the scripts to embed are composed to be returned as simple string <script> tag(s). I find this extremely useful especially when I'm not connected to the internet so that I can quickly swap in a local jQuery resource instead of loading from CDN. While CDN loading with the fallback works it can be a bit slow as the CDN is probed first before the fallback kicks in. Switching quickly in one place makes this trivial. It also makes it very easy once a new version of jQuery rolls around to move up to the new version and ensure that all pages are using the new version immediately. I'm not trying to make this out as 'the' definite way to load your resources, but rather provide it here as a pointer so you can maybe apply your own logic to determine where scripts come from and how they load. You could even automate this some more by using configuration settings or reading the locations/preferences out of some sort of data/metadata store that can be dynamically updated instead via recompilation. FWIW, I use a very similar approach for loading jQuery UI and my own ww.jquery library - the same concept can be applied to any kind of script you might be loading from different locations. Hopefully some of you find this a useful addition to your toolset. Resources Google CDN for jQuery Full ControlResources Source Code ControlResource Documentation Westwind.Web NuGet This method is part of the Westwind.Web library of the West Wind Web Toolkit or you can grab the Web library from NuGet and add to your Visual Studio project. This package includes a host of Web related utilities and script support features. © Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET jQuery Tweet (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); })();

Read the article

Detecting HTML5/CSS3 Features using Modernizr

- by dwahlin

HTML5, CSS3, and related technologies such as canvas and web sockets bring a lot of useful new features to the table that can take Web applications to the next level. These new technologies allow applications to be built using only HTML, CSS, and JavaScript allowing them to be viewed on a variety of form factors including tablets and phones. Although HTML5 features offer a lot of promise, it’s not realistic to develop applications using the latest technologies without worrying about supporting older browsers in the process. If history has taught us anything it’s that old browsers stick around for years and years which means developers have to deal with backward compatibility issues. This is especially true when deploying applications to the Internet that target the general public. This begs the question, “How do you move forward with HTML5 and CSS3 technologies while gracefully handling unsupported features in older browsers?” Although you can write code by hand to detect different HTML5 and CSS3 features, it’s not always straightforward. For example, to check for canvas support you need to write code similar to the following: <script> window.onload = function () { if (canvasSupported()) { alert('canvas supported'); } }; function canvasSupported() { var canvas = document.createElement('canvas'); return (canvas.getContext && canvas.getContext('2d')); } </script> If you want to check for local storage support the following check can be made. It’s more involved than it should be due to a bug in older versions of Firefox. <script> window.onload = function () { if (localStorageSupported()) { alert('local storage supported'); } }; function localStorageSupported() { try { return ('localStorage' in window && window['localStorage'] != null); } catch(e) {} return false; } </script> Looking through the previous examples you can see that there’s more than meets the eye when it comes to checking browsers for HTML5 and CSS3 features. It takes a lot of work to test every possible scenario and every version of a given browser. Fortunately, you don’t have to resort to writing custom code to test what HTML5/CSS3 features a given browser supports. By using a script library called Modernizr you can add checks for different HTML5/CSS3 features into your pages with a minimal amount of code on your part. Let’s take a look at some of the key features Modernizr offers. Getting Started with Modernizr The first time I heard the name “Modernizr” I thought it “modernized” older browsers by added missing functionality. In reality, Modernizr doesn’t actually handle adding missing features or “modernizing” older browsers. The Modernizr website states, “The name Modernizr actually stems from the goal of modernizing our development practices (and ourselves)”. Because it relies on feature detection rather than browser sniffing (a common technique used in the past – that never worked that great), Modernizr definitely provides a more modern way to test features that a browser supports and can even handle loading additional scripts called shims or polyfills that fill in holes that older browsers may have. It’s a great tool to have in your arsenal if you’re a web developer. Modernizr is available at http://modernizr.com. Two different types of scripts are available including a development script and custom production script. To generate a production script, the site provides a custom script generation tool rather than providing a single script that has everything under the sun for HTML5/CSS3 feature detection. Using the script generation tool you can pick the specific test functionality that you need and ignore everything that you don’t need. That way the script is kept as small as possible. An example of the custom script download screen is shown next. Notice that specific CSS3, HTML5, and related feature tests can be selected. Once you’ve downloaded your custom script you can add it into your web page using the standard <script> element and you’re ready to start using Modernizr. <script src="Scripts/Modernizr.js" type="text/javascript"></script> Modernizr and the HTML Element Once you’ve add a script reference to Modernizr in a page it’ll go to work for you immediately. In fact, by adding the script several different CSS classes will be added to the page’s <html> element at runtime. These classes define what features the browser supports and what features it doesn’t support. Features that aren’t supported get a class name of “no-FeatureName”, for example “no-flexbox”. Features that are supported get a CSS class name based on the feature such as “canvas” or “websockets”. An example of classes added when running a page in Chrome is shown next: <html class=" js flexbox canvas canvastext webgl no-touch geolocation postmessage websqldatabase indexeddb hashchange history draganddrop websockets rgba hsla multiplebgs backgroundsize borderimage borderradius boxshadow textshadow opacity cssanimations csscolumns cssgradients cssreflections csstransforms csstransforms3d csstransitions fontface generatedcontent video audio localstorage sessionstorage webworkers applicationcache svg inlinesvg smil svgclippaths"> Here’s an example of what the <html> element looks like at runtime with Internet Explorer 9: <html class=" js no-flexbox canvas canvastext no-webgl no-touch geolocation postmessage no-websqldatabase no-indexeddb hashchange no-history draganddrop no-websockets rgba hsla multiplebgs backgroundsize no-borderimage borderradius boxshadow no-textshadow opacity no-cssanimations no-csscolumns no-cssgradients no-cssreflections csstransforms no-csstransforms3d no-csstransitions fontface generatedcontent video audio localstorage sessionstorage no-webworkers no-applicationcache svg inlinesvg smil svgclippaths"> When using Modernizr it’s a common practice to define an <html> element in your page with a no-js class added as shown next: <html class="no-js"> You’ll see starter projects such as HTML5 Boilerplate (http://html5boilerplate.com) or Initializr (http://initializr.com) follow this approach (see my previous post for more information on HTML5 Boilerplate). By adding the no-js class it’s easy to tell if a browser has JavaScript enabled or not. If JavaScript is disabled then no-js will stay on the <html> element. If JavaScript is enabled, no-js will be removed by Modernizr and a js class will be added along with other classes that define supported/unsupported features. Working with HTML5 and CSS3 Features You can use the CSS classes added to the <html> element directly in your CSS files to determine what style properties to use based upon the features supported by a given browser. For example, the following CSS can be used to render a box shadow for browsers that support that feature and a simple border for browsers that don’t support the feature: .boxshadow #MyContainer { border: none; -webkit-box-shadow: #666 1px 1px 1px; -moz-box-shadow: #666 1px 1px 1px; } .no-boxshadow #MyContainer { border: 2px solid black; } If a browser supports box-shadows the boxshadow CSS class will be added to the <html> element by Modernizr. It can then be associated with a given element. This example associates the boxshadow class with a div with an id of MyContainer. If the browser doesn’t support box shadows then the no-boxshadow class will be added to the <html> element and it can be used to render a standard border around the div. This provides a great way to leverage new CSS3 features in supported browsers while providing a graceful fallback for older browsers. In addition to using the CSS classes that Modernizr provides on the <html> element, you also use a global Modernizr object that’s created. This object exposes different properties that can be used to detect the availability of specific HTML5 or CSS3 features. For example, the following code can be used to detect canvas and local storage support. You can see that the code is much simpler than the code shown at the beginning of this post. It also has the added benefit of being tested by a large community of web developers around the world running a variety of browsers. $(document).ready(function () { if (Modernizr.canvas) { //Add canvas code } if (Modernizr.localstorage) { //Add local storage code } }); The global Modernizr object can also be used to test for the presence of CSS3 features. The following code shows how to test support for border-radius and CSS transforms: $(document).ready(function () { if (Modernizr.borderradius) { $('#MyDiv').addClass('borderRadiusStyle'); } if (Modernizr.csstransforms) { $('#MyDiv').addClass('transformsStyle'); } }); Several other CSS3 feature tests can be performed such as support for opacity, rgba, text-shadow, CSS animations, CSS transitions, multiple backgrounds, and more. A complete list of supported HTML5 and CSS3 tests that Modernizr supports can be found at http://www.modernizr.com/docs. Loading Scripts using Modernizr In cases where a browser doesn’t support a specific feature you can either provide a graceful fallback or load a shim/polyfill script to fill in missing functionality where appropriate (more information about shims/polyfills can be found at https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-Browser-Polyfills). Modernizr has a built-in script loader that can be used to test for a feature and then load a script if the feature isn’t available. The script loader is built-into Modernizr and is also available as a standalone yepnope script (http://yepnopejs.com). It’s extremely easy to get started using the script loader and it can really simplify the process of loading scripts based on the availability of a particular browser feature. To load scripts dynamically you can use Modernizr’s load() function which accepts properties defining the feature to test (test property), the script to load if the test succeeds (yep property), the script to load if the test fails (nope property), and a script to load regardless of if the test succeeds or fails (both property). An example of using load() with these properties is show next: Modernizr.load({ test: Modernizr.canvas, yep: 'html5CanvasAvailable.js’, nope: 'excanvas.js’, both: 'myCustomScript.js' }); In this example Modernizr is used to not only load scripts but also to test for the presence of the canvas feature. If the target browser supports the HTML5 canvas then the html5CanvasAvailable.js script will be loaded along with the myCustomScript.js script (use of the yep property in this example is a bit contrived – it was added simply to demonstrate how the property can be used in the load() function). Otherwise, a polyfill script named excanvas.js will be loaded to add missing canvas functionality for Internet Explorer versions prior to 9. Once excanvas.js is loaded the myCustomScript.js script will be loaded. Because Modernizr handles loading scripts, you can also use it in creative ways. For example, you can use it to load local scripts when a 3rd party Content Delivery Network (CDN) such as one provided by Google or Microsoft is unavailable for whatever reason. The Modernizr documentation provides the following example that demonstrates the process for providing a local fallback for jQuery when a CDN is down: Modernizr.load([ { load: '//ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.js', complete: function () { if (!window.jQuery) { Modernizr.load('js/libs/jquery-1.6.4.min.js'); } } }, { // This will wait for the fallback to load and // execute if it needs to. load: 'needs-jQuery.js' } ]); This code attempts to load jQuery from the Google CDN first. Once the script is downloaded (or if it fails) the function associated with complete will be called. The function checks to make sure that the jQuery object is available and if it’s not Modernizr is used to load a local jQuery script. After all of that occurs a script named needs-jQuery.js will be loaded. Conclusion If you’re building applications that use some of the latest and greatest features available in HTML5 and CSS3 then Modernizr is an essential tool. By using it you can reduce the amount of custom code required to test for browser features and provide graceful fallbacks or even load shim/polyfill scripts for older browsers to help fill in missing functionality.

Read the article

Detecting HTML5/CSS3 Features using Modernizr

- by dwahlin

HTML5, CSS3, and related technologies such as canvas and web sockets bring a lot of useful new features to the table that can take Web applications to the next level. These new technologies allow applications to be built using only HTML, CSS, and JavaScript allowing them to be viewed on a variety of form factors including tablets and phones. Although HTML5 features offer a lot of promise, it’s not realistic to develop applications using the latest technologies without worrying about supporting older browsers in the process. If history has taught us anything it’s that old browsers stick around for years and years which means developers have to deal with backward compatibility issues. This is especially true when deploying applications to the Internet that target the general public. This begs the question, “How do you move forward with HTML5 and CSS3 technologies while gracefully handling unsupported features in older browsers?” Although you can write code by hand to detect different HTML5 and CSS3 features, it’s not always straightforward. For example, to check for canvas support you need to write code similar to the following: <script> window.onload = function () { if (canvasSupported()) { alert('canvas supported'); } }; function canvasSupported() { var canvas = document.createElement('canvas'); return (canvas.getContext && canvas.getContext('2d')); } </script> If you want to check for local storage support the following check can be made. It’s more involved than it should be due to a bug in older versions of Firefox. <script> window.onload = function () { if (localStorageSupported()) { alert('local storage supported'); } }; function localStorageSupported() { try { return ('localStorage' in window && window['localStorage'] != null); } catch(e) {} return false; } </script> Looking through the previous examples you can see that there’s more than meets the eye when it comes to checking browsers for HTML5 and CSS3 features. It takes a lot of work to test every possible scenario and every version of a given browser. Fortunately, you don’t have to resort to writing custom code to test what HTML5/CSS3 features a given browser supports. By using a script library called Modernizr you can add checks for different HTML5/CSS3 features into your pages with a minimal amount of code on your part. Let’s take a look at some of the key features Modernizr offers. Getting Started with Modernizr The first time I heard the name “Modernizr” I thought it “modernized” older browsers by added missing functionality. In reality, Modernizr doesn’t actually handle adding missing features or “modernizing” older browsers. The Modernizr website states, “The name Modernizr actually stems from the goal of modernizing our development practices (and ourselves)”. Because it relies on feature detection rather than browser sniffing (a common technique used in the past – that never worked that great), Modernizr definitely provides a more modern way to test features that a browser supports and can even handle loading additional scripts called shims or polyfills that fill in holes that older browsers may have. It’s a great tool to have in your arsenal if you’re a web developer. Modernizr is available at http://modernizr.com. Two different types of scripts are available including a development script and custom production script. To generate a production script, the site provides a custom script generation tool rather than providing a single script that has everything under the sun for HTML5/CSS3 feature detection. Using the script generation tool you can pick the specific test functionality that you need and ignore everything that you don’t need. That way the script is kept as small as possible. An example of the custom script download screen is shown next. Notice that specific CSS3, HTML5, and related feature tests can be selected. Once you’ve downloaded your custom script you can add it into your web page using the standard <script> element and you’re ready to start using Modernizr. <script src="Scripts/Modernizr.js" type="text/javascript"></script> Modernizr and the HTML Element Once you’ve add a script reference to Modernizr in a page it’ll go to work for you immediately. In fact, by adding the script several different CSS classes will be added to the page’s <html> element at runtime. These classes define what features the browser supports and what features it doesn’t support. Features that aren’t supported get a class name of “no-FeatureName”, for example “no-flexbox”. Features that are supported get a CSS class name based on the feature such as “canvas” or “websockets”. An example of classes added when running a page in Chrome is shown next: <html class=" js flexbox canvas canvastext webgl no-touch geolocation postmessage websqldatabase indexeddb hashchange history draganddrop websockets rgba hsla multiplebgs backgroundsize borderimage borderradius boxshadow textshadow opacity cssanimations csscolumns cssgradients cssreflections csstransforms csstransforms3d csstransitions fontface generatedcontent video audio localstorage sessionstorage webworkers applicationcache svg inlinesvg smil svgclippaths"> Here’s an example of what the <html> element looks like at runtime with Internet Explorer 9: <html class=" js no-flexbox canvas canvastext no-webgl no-touch geolocation postmessage no-websqldatabase no-indexeddb hashchange no-history draganddrop no-websockets rgba hsla multiplebgs backgroundsize no-borderimage borderradius boxshadow no-textshadow opacity no-cssanimations no-csscolumns no-cssgradients no-cssreflections csstransforms no-csstransforms3d no-csstransitions fontface generatedcontent video audio localstorage sessionstorage no-webworkers no-applicationcache svg inlinesvg smil svgclippaths"> When using Modernizr it’s a common practice to define an <html> element in your page with a no-js class added as shown next: <html class="no-js"> You’ll see starter projects such as HTML5 Boilerplate (http://html5boilerplate.com) or Initializr (http://initializr.com) follow this approach (see my previous post for more information on HTML5 Boilerplate). By adding the no-js class it’s easy to tell if a browser has JavaScript enabled or not. If JavaScript is disabled then no-js will stay on the <html> element. If JavaScript is enabled, no-js will be removed by Modernizr and a js class will be added along with other classes that define supported/unsupported features. Working with HTML5 and CSS3 Features You can use the CSS classes added to the <html> element directly in your CSS files to determine what style properties to use based upon the features supported by a given browser. For example, the following CSS can be used to render a box shadow for browsers that support that feature and a simple border for browsers that don’t support the feature: .boxshadow #MyContainer { border: none; -webkit-box-shadow: #666 1px 1px 1px; -moz-box-shadow: #666 1px 1px 1px; } .no-boxshadow #MyContainer { border: 2px solid black; } If a browser supports box-shadows the boxshadow CSS class will be added to the <html> element by Modernizr. It can then be associated with a given element. This example associates the boxshadow class with a div with an id of MyContainer. If the browser doesn’t support box shadows then the no-boxshadow class will be added to the <html> element and it can be used to render a standard border around the div. This provides a great way to leverage new CSS3 features in supported browsers while providing a graceful fallback for older browsers. In addition to using the CSS classes that Modernizr provides on the <html> element, you also use a global Modernizr object that’s created. This object exposes different properties that can be used to detect the availability of specific HTML5 or CSS3 features. For example, the following code can be used to detect canvas and local storage support. You can see that the code is much simpler than the code shown at the beginning of this post. It also has the added benefit of being tested by a large community of web developers around the world running a variety of browsers. $(document).ready(function () { if (Modernizr.canvas) { //Add canvas code } if (Modernizr.localstorage) { //Add local storage code } }); The global Modernizr object can also be used to test for the presence of CSS3 features. The following code shows how to test support for border-radius and CSS transforms: $(document).ready(function () { if (Modernizr.borderradius) { $('#MyDiv').addClass('borderRadiusStyle'); } if (Modernizr.csstransforms) { $('#MyDiv').addClass('transformsStyle'); } }); Several other CSS3 feature tests can be performed such as support for opacity, rgba, text-shadow, CSS animations, CSS transitions, multiple backgrounds, and more. A complete list of supported HTML5 and CSS3 tests that Modernizr supports can be found at http://www.modernizr.com/docs. Loading Scripts using Modernizr In cases where a browser doesn’t support a specific feature you can either provide a graceful fallback or load a shim/polyfill script to fill in missing functionality where appropriate (more information about shims/polyfills can be found at https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-Browser-Polyfills). Modernizr has a built-in script loader that can be used to test for a feature and then load a script if the feature isn’t available. The script loader is built-into Modernizr and is also available as a standalone yepnope script (http://yepnopejs.com). It’s extremely easy to get started using the script loader and it can really simplify the process of loading scripts based on the availability of a particular browser feature. To load scripts dynamically you can use Modernizr’s load() function which accepts properties defining the feature to test (test property), the script to load if the test succeeds (yep property), the script to load if the test fails (nope property), and a script to load regardless of if the test succeeds or fails (both property). An example of using load() with these properties is show next: Modernizr.load({ test: Modernizr.canvas, yep: 'html5CanvasAvailable.js’, nope: 'excanvas.js’, both: 'myCustomScript.js' }); In this example Modernizr is used to not only load scripts but also to test for the presence of the canvas feature. If the target browser supports the HTML5 canvas then the html5CanvasAvailable.js script will be loaded along with the myCustomScript.js script (use of the yep property in this example is a bit contrived – it was added simply to demonstrate how the property can be used in the load() function). Otherwise, a polyfill script named excanvas.js will be loaded to add missing canvas functionality for Internet Explorer versions prior to 9. Once excanvas.js is loaded the myCustomScript.js script will be loaded. Because Modernizr handles loading scripts, you can also use it in creative ways. For example, you can use it to load local scripts when a 3rd party Content Delivery Network (CDN) such as one provided by Google or Microsoft is unavailable for whatever reason. The Modernizr documentation provides the following example that demonstrates the process for providing a local fallback for jQuery when a CDN is down: Modernizr.load([ { load: '//ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.js', complete: function () { if (!window.jQuery) { Modernizr.load('js/libs/jquery-1.6.4.min.js'); } } }, { // This will wait for the fallback to load and // execute if it needs to. load: 'needs-jQuery.js' } ]); This code attempts to load jQuery from the Google CDN first. Once the script is downloaded (or if it fails) the function associated with complete will be called. The function checks to make sure that the jQuery object is available and if it’s not Modernizr is used to load a local jQuery script. After all of that occurs a script named needs-jQuery.js will be loaded. Conclusion If you’re building applications that use some of the latest and greatest features available in HTML5 and CSS3 then Modernizr is an essential tool. By using it you can reduce the amount of custom code required to test for browser features and provide graceful fallbacks or even load shim/polyfill scripts for older browsers to help fill in missing functionality.

Read the article

A BASH script that will copy the contents of the directory so long as the average system load is low

- by Necessary

For reasons I won't get into, I need to copy directories so long as the average system load is low. Can someone help me write a BASH script that will copy the contents of a directory, but check to make sure the average system load is below X before copying each file, and if not, wait Y seconds and try again?

Read the article

How do I load external images into Excel? [duplicate]

- by Cocoa Dev

This question already has an answer here: Inserting a (jpg) picture into a cell in Microsoft Excel 2007 1 answer I have a table with a column of links (URLs) to images. I want to load the linked images into the next cell over. For example: A1 contains http://example.com/image.jpg I want to load the image in B1. How can I do it?

Read the article

Why i can not load a simple pixel shader effect (. fx) file in xna?

- by Mehdi Bugnard

I just want to load a simple *.fx file into my project to make a (pixel shader) effect. But whenever I try to compile my project, I get the following error in visual studio Error List: Errors compiling .. ID3DXEffectCompiler: There were no techniques ID3DXEffectCompiler: Compilation failed I already searched on google and found many people with the same problem. And I realized that it was a problem of encoding. With the return lines unrecognized '\ n' . I tried to copy and paste to notepad and save as with ASCII or UTF8 encoding. But the result is always the same. Do you have an idea please ? Thanks a looot :-) Here is my [.fx] file : sampler BaseTexture : register(s0); sampler MaskTexture : register(s1) { addressU = Clamp; addressV = Clamp; }; //All of these variables are pixel values //Feel free to replace with float2 variables float MaskLocationX; float MaskLocationY; float MaskWidth; float MaskHeight; float BaseTextureLocationX; //This is where your texture is to be drawn float BaseTextureLocationY; //texCoord is different, it is the current pixel float BaseTextureWidth; float BaseTextureHeight; float4 main(float2 texCoord : TEXCOORD0) : COLOR0 { //We need to calculate where in terms of percentage to sample from the MaskTexture float maskPixelX = texCoord.x * BaseTextureWidth + BaseTextureLocationX; float maskPixelY = texCoord.y * BaseTextureHeight + BaseTextureLocationY; float2 maskCoord = float2((maskPixelX - MaskLocationX) / MaskWidth, (maskPixelY - MaskLocationY) / MaskHeight); float4 bitMask = tex2D(MaskTexture, maskCoord); float4 tex = tex2D(BaseTexture, texCoord); //It is a good idea to avoid conditional statements in a pixel shader if you can use math instead. return tex * (bitMask.a); //Alternate calculation to invert the mask, you could make this a parameter too if you wanted //return tex * (1.0 - bitMask.a); }

Read the article

Visual Studio 2010 Service Pack 1 Released

- by krislankford

The VS 2010 SP 1 release was simultaneous to the release of TFS 2010 SP1 and includes support for the Project Server Integration Feature Pack and updates to .NET Framework 4.0. The complete Visual Studio SP1 list including Test and Lab Manager: http://support.microsoft.com/kb/983509 The release addresses some of the most requested features from customers of Visual Studio 2010 like better help support IntelliTrace support for 64bit and SharePoint Silverlight 4 Tools in the box unit testing support on .NET 3.5 a new performance wizard for Silverlight Another major addition is the announcement of Unlimited Load Testing for Visual Studio 2010 Ultimate with MSDN Subscribers! The benefits of Visual Studio 2010 Load Test Feature Pack and useful links: Improved Overall Software Quality through Early Lifecycle Performance Testing: Lets you stress test your application early and throughout its development lifecycle with realistically modeled simulated load. By integrating performance validations early into your applications, you can ensure that your solution copes with real-world demands and behaves in a predictable manner, effectively increasing overall software quality. Higher Productivity and Reduced TCO with the Ability to Scale without Incremental Costs: Development teams no longer have to purchase Visual Studio Load Test Virtual User Pack 2010. Download the Visual Studio 2010 Load Test Feature Pack Deployment Guide Get started with stress and performance testing with Visual Studio 2010 Ultimate: Quality Solutions Best Practice: Enabling Performance and Stress Testing throughout the Application Lifecycle Hands-On-Lab: Introduction to Load Testing with ASP.NET Profile in Visual Studio 2010 How-Do-I videos: Use ASP.NET Profiler in Load Tests Use Network Emulation in Load Tests VHD/VPC walkthrough: Getting Started with Load and Performance Testing Best Practice guidance: Visual Studio Performance Testing Quick Reference Guide

Read the article

Calendar issue in simple java form using swing package?

- by Rand Mate

I have created a form using java swing package, For the purpose of adding Date of Birth in the form I have used the following code particularly to add in java Frame via Swing Package. Is there any alternative way to simplify the code. JLabel l2 = new JLabel("Date of Birth"); l2.setBounds(200,160,100,20); String day[] ={"1","2","3","4","5","6","7","8","9","10","11","12","13","14","15","16","17","18","19","20","21","22","23","24","25","26","27","28","29","30"}; String month[] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"}; String year[] = {"2012","2011","2010","2009","2008","2007","2006","2005","2004","2003","2002","2001","2000","1999","1998","1997","1996","1995","1994","1993","1992","1991","1990","1989","1988","1987","1986","1985","1984","1983","1982","1981","1980","1979","1976","1975"}; JComboBox cb1 = new JComboBox(day); cb1.setBounds(450,160,50,20); JComboBox cb2 = new JComboBox(month); cb2.setBounds(500,160,50,20); JComboBox cb3 = new JComboBox(year); cb3.setBounds(550,160,60,20);

Read the article

Have you Been Missing the 'About This Record' Functionality on the Customer Form...?

- by MargaretW

Do you have fond memories of the 'Help -> About This Record' functionality that used to be available in the old Customer form - when it was a form, and not a java html screen? Back in Release 11i, we had the ability to identify when the customer record had last been updated and by whom. When some forms were replaced by Java HTML screens, you could identify some of this information via the 'About this Page' hyperlink at the bottom left hand corner of the HTML page. You could enable this by enabling the FND: Diagnostics profile option, but many customers found this had an adverse effect on performance and additionally was not user-friendly. Our customers tell us that this feature was widely used to identify owner/update information in many business processes, including auditing, customer entry/update, research and testing. There have been various efforts to revert this feature by customising java pages, but this was not fully successful in some cases. Oracle Support is happy to announce that this functionality has now been included in the Customer screens in Release 12.2 onwards. You will be able to query the record history at customer level, at site level, at site address levels and for all tabs relating to the customer. Simply click on the 'Record History' icon, available in the Record History column on a summary screen, or via the same icon on the individual detail screen to display the following information: Last Updated Date: Last Updated By Creation Date Created By Last Update Login

Read the article

Hard-drive will randomly fail to load GRUB. Booting a live USB/CD fixes the issue temporarily

- by Usagi

I am running 12.04 64-bit and am dual booting with Win7, for full disclosure, although I suspect that has nothing to do with my problem. Occasionally the boot-loader(GRUB) will fail to load and I will be presented with a black screen with a single blinking line. There is no apparent pattern although I suspect there is one and it is related to a program I am running. This has happened to me eight out of ten power cycles now and I can fix it consistently, however, I have no idea why it happens. My current fix is to boot a live CD (I've tried both KNOPPIX and Ubuntu with the same result) and that's it. Somehow booting with the live CD is enough to "wake-up" my hard drive. I then reboot and GRUB magically appears again. So what is going on? Is it possible that a program is corrupting my MBR and the live CD is restoring it? How can I narrow down the possibilities? Thanks. Additional: This is still a problem. I'm convinced now that it is not hardware related as I've spent the last month and several boot cycles on Windows without a hiccup. Recently when I started using Ubuntu again the problem started again. I am more interested in figuring out what is going on rather than actually fixing the problem. Are there any tools, logs, etc. I can use to unravel this mystery?

Read the article

MS Access 2003 - Unbound Form uses INSERT statement to save to table; what about subforms?

- by Justin

So I have an unbound form that I use to save data to a table on button click. Is there a way I can have subforms for entry that will allow me to save data to the table within that same button click? Basically I want to add more entry options for the user, and while I know other ways to do it, I am particularly curious about doing it this way (if it can be done). So lets say the 'parent form' is frmMain. And there are two child forms "sub1" and "sub2". Just for example sake lets say on frmMain there are two text boxes: txtTitle & txtAuthor. sub1 and sub2 both have a text Box on them that represent something like prices. The idea is Title & author of a book, and then a price at each store (simplified). So I tried this (because I thought it was worth a shot): Dim db as DAO.database Dim sql as String sql = "INSERT INTO (Title, Author, PriceA, PriceB) VALUES (" if not isnull(me.txtTitle) then sql = sql & """" & me.txtTitle & """," Else sql = sql & " NULL," End If if not IsNull(me.txtAuthor) then sql = sql & " """ & me.txtAuthor & """," else sql = sql & " NULL," end if if not IsNull (forms!sub1.txtPrice) then sql = sql & " """ & forms!sub1.txtPrice & """," else sql = sql & " NULL," end if without finishing the code, i think you may see the GOTCHA i am headed for. I tried this and got an "Access cannot find the form "" ". I think I can pretty much see why on this approach too, because when I click the button that calls the new sub form into the parent form, the values that were just entered are not held/saved as sub1 closes and sub2 opens. I should mention that the idea above is not intended to be a one or the other approach, rather both sub forms used everytime. so this is an example. i want to use this method (if possible) to have about 7 different sub form choices in one form, and be able to save to a table via a SQL statement. I realize that there may be better ways, but I am just wondering if I can get there with this approach out of curiousity. Thanks as always!

Read the article

How to resolve strange conflict between form post and ajax post?

- by Oliver Hyde

On the one page, I am trying to use ajax to edit existing values. I am doing this by using jQuery Inline Edit and posting away the new data, updating the record and returning with success. This is working fine. Next I have implemented the ability to add new records, to do this I have a form at the end of the table, which submits post data then redirects back to the original page. Each of them work individually, but after I have used the form to add a new record, the inline editing stops to work. If I close the webpage and reopen it, it works fine again until I have used the form and it goes of the rails again. I have tried a number of solutions, clearing session data, giving the form a separate name, redirecting to an alternative page (which does work, but is not ideal as I want the form to redirect back to the original location ). Here is a sample of the view form data: <?php foreach($week->incomes as $income):?> <tr> <td><?php echo $income->name;?></td> <td width="70" style="text-align:right;" class="editableSingle income id<?php echo $income->id;?>">$<?php echo $income->cost;?></td> </tr> <?php endforeach;?> <?php echo form_open('budget/add/'.$week->id.'/income/index', 'class="form-vertical" id="add_income"'); ?> <tr> <td> <input type="text" name="name" class="input-small" placeholder="Name"> <input type="text" name="cost" class="input-small" placeholder="Cost"> </td> <td> <button type="submit" class="btn btn-small pull-right"><i class="icon-plus "></i></button> </td> </tr> <?php echo form_close(); ?> This is the javascript initialisation code: $(function(){ $.inlineEdit({ income: 'budget/update_income/', expense: 'budget/update_expense/' }, { animate: false, filterElementValue: function($o){ if ($o.hasClass('income')) { return $o.html().match(/\$(.+)/)[1]; } else if ($o.hasClass('expense')) { return $o.html().match(/\$(.+)/)[1]; } else { return $o.html(); } }, afterSave: function(o){ if (o.type == 'income') { $('.income.id' + o.id).prepend('$'); } if (o.type == 'expense') { $('.expense.id' + o.id).prepend('$'); } }, colors: { error:'green' } }); }); If I can provide any more information to clarify what I have attempted etc, let me know. Temporary Fix It seems I have come up with a work around, not ideal as I still am not sure what is causing the issue. I have created a method called redirect. public function redirect(){ redirect(''); } am now calling that after the form submit which has temporarily allows my multiple post submits to work.

Read the article

Could not load file or assembly 'GMap.NET.Core' or one of its dependencies. An attempt was made to load a program with an incorrect format.

- by Sam M

I have a wcf Service application in VS2010.My local machine is a 32 bit OS where as the server is a 64 bit. There are around 6 services in my solution. Im successfully able to host the application on IIS on my local machine.And it works fine. But when i try host that service application on Server i gets the below error Could not load file or assembly 'GMap.NET.Core' or one of its dependencies. An attempt was made to load a program with an incorrect format. I do have reference added in my solution for GMap.NET.Core . I have tried to set the properties in my solution to Any CPU . Also in the application pool i have set the Enable 32-Bit Application to True. i have also set the Copy Local to TRUE in my solution before publishing. When i run the source on through my solution i dont get any error and the solution is built successfully. What else can i try to get my services successfully hosted on the Server and should be accessed through my application.

Read the article

Upload File to Windows Azure Blob in Chunks through ASP.NET MVC, JavaScript and HTML5

- by Shaun

Originally posted on: http://geekswithblogs.net/shaunxu/archive/2013/07/01/upload-file-to-windows-azure-blob-in-chunks-through-asp.net.aspxMany people are using Windows Azure Blob Storage to store their data in the cloud. Blob storage provides 99.9% availability with easy-to-use API through .NET SDK and HTTP REST. For example, we can store JavaScript files, images, documents in blob storage when we are building an ASP.NET web application on a Web Role in Windows Azure. Or we can store our VHD files in blob and mount it as a hard drive in our cloud service. If you are familiar with Windows Azure, you should know that there are two kinds of blob: page blob and block blob. The page blob is optimized for random read and write, which is very useful when you need to store VHD files. The block blob is optimized for sequential/chunk read and write, which has more common usage. Since we can upload block blob in blocks through BlockBlob.PutBlock, and them commit them as a whole blob with invoking the BlockBlob.PutBlockList, it is very powerful to upload large files, as we can upload blocks in parallel, and provide pause-resume feature. There are many documents, articles and blog posts described on how to upload a block blob. Most of them are focus on the server side, which means when you had received a big file, stream or binaries, how to upload them into blob storage in blocks through .NET SDK. But the problem is, how can we upload these large files from client side, for example, a browser. This questioned to me when I was working with a Chinese customer to help them build a network disk production on top of azure. The end users upload their files from the web portal, and then the files will be stored in blob storage from the Web Role. My goal is to find the best way to transform the file from client (end user’s machine) to the server (Web Role) through browser. In this post I will demonstrate and describe what I had done, to upload large file in chunks with high speed, and save them as blocks into Windows Azure Blob Storage. Traditional Upload, Works with Limitation The simplest way to implement this requirement is to create a web page with a form that contains a file input element and a submit button. 1: @using (Html.BeginForm("About", "Index", FormMethod.Post, new { enctype = "multipart/form-data" })) 2: { 3: <input type="file" name="file" /> 4: <input type="submit" value="upload" /> 5: } And then in the backend controller, we retrieve the whole content of this file and upload it in to the blob storage through .NET SDK. We can split the file in blocks and upload them in parallel and commit. The code had been well blogged in the community. 1: [HttpPost] 2: public ActionResult About(HttpPostedFileBase file) 3: { 4: var container = _client.GetContainerReference("test"); 5: container.CreateIfNotExists(); 6: var blob = container.GetBlockBlobReference(file.FileName); 7: var blockDataList = new Dictionary<string, byte[]>(); 8: using (var stream = file.InputStream) 9: { 10: var blockSizeInKB = 1024; 11: var offset = 0; 12: var index = 0; 13: while (offset < stream.Length) 14: { 15: var readLength = Math.Min(1024 * blockSizeInKB, (int)stream.Length - offset); 16: var blockData = new byte[readLength]; 17: offset += stream.Read(blockData, 0, readLength); 18: blockDataList.Add(Convert.ToBase64String(BitConverter.GetBytes(index)), blockData); 19: 20: index++; 21: } 22: } 23: 24: Parallel.ForEach(blockDataList, (bi) => 25: { 26: blob.PutBlock(bi.Key, new MemoryStream(bi.Value), null); 27: }); 28: blob.PutBlockList(blockDataList.Select(b => b.Key).ToArray()); 29: 30: return RedirectToAction("About"); 31: } This works perfect if we selected an image, a music or a small video to upload. But if I selected a large file, let’s say a 6GB HD-movie, after upload for about few minutes the page will be shown as below and the upload will be terminated. In ASP.NET there is a limitation of request length and the maximized request length is defined in the web.config file. It’s a number which less than about 4GB. So if we want to upload a really big file, we cannot simply implement in this way. Also, in Windows Azure, a cloud service network load balancer will terminate the connection if exceed the timeout period. From my test the timeout looks like 2 - 3 minutes. Hence, when we need to upload a large file we cannot just use the basic HTML elements. Besides the limitation mentioned above, the simple HTML file upload cannot provide rich upload experience such as chunk upload, pause and pause-resume. So we need to find a better way to upload large file from the client to the server. Upload in Chunks through HTML5 and JavaScript In order to break those limitation mentioned above we will try to upload the large file in chunks. This takes some benefit to us such as - No request size limitation: Since we upload in chunks, we can define the request size for each chunks regardless how big the entire file is. - No timeout problem: The size of chunks are controlled by us, which means we should be able to make sure request for each chunk upload will not exceed the timeout period of both ASP.NET and Windows Azure load balancer. It was a big challenge to upload big file in chunks until we have HTML5. There are some new features and improvements introduced in HTML5 and we will use them to implement our solution. In HTML5, the File interface had been improved with a new method called “slice”. It can be used to read part of the file by specifying the start byte index and the end byte index. For example if the entire file was 1024 bytes, file.slice(512, 768) will read the part of this file from the 512nd byte to 768th byte, and return a new object of interface called "Blob”, which you can treat as an array of bytes. In fact, a Blob object represents a file-like object of immutable, raw data. The File interface is based on Blob, inheriting blob functionality and expanding it to support files on the user's system. For more information about the Blob please refer here. File and Blob is very useful to implement the chunk upload. We will use File interface to represent the file the user selected from the browser and then use File.slice to read the file in chunks in the size we wanted. For example, if we wanted to upload a 10MB file with 512KB chunks, then we can read it in 512KB blobs by using File.slice in a loop. Assuming we have a web page as below. User can select a file, an input box to specify the block size in KB and a button to start upload. 1: <div> 2: <input type="file" id="upload_files" name="files[]" /><br /> 3: Block Size: <input type="number" id="block_size" value="512" name="block_size" />KB<br /> 4: <input type="button" id="upload_button_blob" name="upload" value="upload (blob)" /> 5: </div> Then we can have the JavaScript function to upload the file in chunks when user clicked the button. 1: <script type="text/javascript"> 1: 2: $(function () { 3: $("#upload_button_blob").click(function () { 4: }); 5: });</script> Firstly we need to ensure the client browser supports the interfaces we are going to use. Just try to invoke the File, Blob and FormData from the “window” object. If any of them is “undefined” the condition result will be “false” which means your browser doesn’t support these premium feature and it’s time for you to get your browser updated. FormData is another new feature we are going to use in the future. It could generate a temporary form for us. We will use this interface to create a form with chunk and associated metadata when invoked the service through ajax. 1: $("#upload_button_blob").click(function () { 2: // assert the browser support html5 3: if (window.File && window.Blob && window.FormData) { 4: alert("Your brwoser is awesome, let's rock!"); 5: } 6: else { 7: alert("Oh man plz update to a modern browser before try is cool stuff out."); 8: return; 9: } 10: }); Each browser supports these interfaces by their own implementation and currently the Blob, File and File.slice are supported by Chrome 21, FireFox 13, IE 10, Opera 12 and Safari 5.1 or higher. After that we worked on the files the user selected one by one since in HTML5, user can select multiple files in one file input box. 1: var files = $("#upload_files")[0].files; 2: for (var i = 0; i < files.length; i++) { 3: var file = files[i]; 4: var fileSize = file.size; 5: var fileName = file.name; 6: } Next, we calculated the start index and end index for each chunks based on the size the user specified from the browser. We put them into an array with the file name and the index, which will be used when we upload chunks into Windows Azure Blob Storage as blocks since we need to specify the target blob name and the block index. At the same time we will store the list of all indexes into another variant which will be used to commit blocks into blob in Azure Storage once all chunks had been uploaded successfully. 1: $("#upload_button_blob").click(function () { 2: // assert the browser support html5 3: ... ... 4: // start to upload each files in chunks 5: var files = $("#upload_files")[0].files; 6: for (var i = 0; i < files.length; i++) { 7: var file = files[i]; 8: var fileSize = file.size; 9: var fileName = file.name; 10: 11: // calculate the start and end byte index for each blocks(chunks) 12: // with the index, file name and index list for future using 13: var blockSizeInKB = $("#block_size").val(); 14: var blockSize = blockSizeInKB * 1024; 15: var blocks = []; 16: var offset = 0; 17: var index = 0; 18: var list = ""; 19: while (offset < fileSize) { 20: var start = offset; 21: var end = Math.min(offset + blockSize, fileSize); 22: 23: blocks.push({ 24: name: fileName, 25: index: index, 26: start: start, 27: end: end 28: }); 29: list += index + ","; 30: 31: offset = end; 32: index++; 33: } 34: } 35: }); Now we have all chunks’ information ready. The next step should be upload them one by one to the server side, and at the server side when received a chunk it will upload as a block into Blob Storage, and finally commit them with the index list through BlockBlobClient.PutBlockList. But since all these invokes are ajax calling, which means not synchronized call. So we need to introduce a new JavaScript library to help us coordinate the asynchronize operation, which named “async.js”. You can download this JavaScript library here, and you can find the document here. I will not explain this library too much in this post. We will put all procedures we want to execute as a function array, and pass into the proper function defined in async.js to let it help us to control the execution sequence, in series or in parallel. Hence we will define an array and put the function for chunk upload into this array. 1: $("#upload_button_blob").click(function () { 2: // assert the browser support html5 3: ... ... 4: 5: // start to upload each files in chunks 6: var files = $("#upload_files")[0].files; 7: for (var i = 0; i < files.length; i++) { 8: var file = files[i]; 9: var fileSize = file.size; 10: var fileName = file.name; 11: // calculate the start and end byte index for each blocks(chunks) 12: // with the index, file name and index list for future using 13: ... ... 14: 15: // define the function array and push all chunk upload operation into this array 16: blocks.forEach(function (block) { 17: putBlocks.push(function (callback) { 18: }); 19: }); 20: } 21: }); 22: }); As you can see, I used File.slice method to read each chunks based on the start and end byte index we calculated previously, and constructed a temporary HTML form with the file name, chunk index and chunk data through another new feature in HTML5 named FormData. Then post this form to the backend server through jQuery.ajax. This is the key part of our solution. 1: $("#upload_button_blob").click(function () { 2: // assert the browser support html5 3: ... ... 4: // start to upload each files in chunks 5: var files = $("#upload_files")[0].files; 6: for (var i = 0; i < files.length; i++) { 7: var file = files[i]; 8: var fileSize = file.size; 9: var fileName = file.name; 10: // calculate the start and end byte index for each blocks(chunks) 11: // with the index, file name and index list for future using 12: ... ... 13: // define the function array and push all chunk upload operation into this array 14: blocks.forEach(function (block) { 15: putBlocks.push(function (callback) { 16: // load blob based on the start and end index for each chunks 17: var blob = file.slice(block.start, block.end); 18: // put the file name, index and blob into a temporary from 19: var fd = new FormData(); 20: fd.append("name", block.name); 21: fd.append("index", block.index); 22: fd.append("file", blob); 23: // post the form to backend service (asp.net mvc controller action) 24: $.ajax({ 25: url: "/Home/UploadInFormData", 26: data: fd, 27: processData: false, 28: contentType: "multipart/form-data", 29: type: "POST", 30: success: function (result) { 31: if (!result.success) { 32: alert(result.error); 33: } 34: callback(null, block.index); 35: } 36: }); 37: }); 38: }); 39: } 40: }); Then we will invoke these functions one by one by using the async.js. And once all functions had been executed successfully I invoked another ajax call to the backend service to commit all these chunks (blocks) as the blob in Windows Azure Storage. 1: $("#upload_button_blob").click(function () { 2: // assert the browser support html5 3: ... ... 4: // start to upload each files in chunks 5: var files = $("#upload_files")[0].files; 6: for (var i = 0; i < files.length; i++) { 7: var file = files[i]; 8: var fileSize = file.size; 9: var fileName = file.name; 10: // calculate the start and end byte index for each blocks(chunks) 11: // with the index, file name and index list for future using 12: ... ... 13: // define the function array and push all chunk upload operation into this array 14: ... ... 15: // invoke the functions one by one 16: // then invoke the commit ajax call to put blocks into blob in azure storage 17: async.series(putBlocks, function (error, result) { 18: var data = { 19: name: fileName, 20: list: list 21: }; 22: $.post("/Home/Commit", data, function (result) { 23: if (!result.success) { 24: alert(result.error); 25: } 26: else { 27: alert("done!"); 28: } 29: }); 30: }); 31: } 32: }); That’s all in the client side. The outline of our logic would be - Calculate the start and end byte index for each chunks based on the block size. - Defined the functions of reading the chunk form file and upload the content to the backend service through ajax. - Execute the functions defined in previous step with “async.js”. - Commit the chunks by invoking the backend service in Windows Azure Storage finally. Save Chunks as Blocks into Blob Storage In above we finished the client size JavaScript code. It uploaded the file in chunks to the backend service which we are going to implement in this step. We will use ASP.NET MVC as our backend service, and it will receive the chunks, upload into Windows Azure Bob Storage in blocks, then finally commit as one blob. As in the client side we uploaded chunks by invoking the ajax call to the URL "/Home/UploadInFormData", I created a new action under the Index controller and it only accepts HTTP POST request. 1: [HttpPost] 2: public JsonResult UploadInFormData() 3: { 4: var error = string.Empty; 5: try 6: { 7: } 8: catch (Exception e) 9: { 10: error = e.ToString(); 11: } 12: 13: return new JsonResult() 14: { 15: Data = new 16: { 17: success = string.IsNullOrWhiteSpace(error), 18: error = error 19: } 20: }; 21: } Then I retrieved the file name, index and the chunk content from the Request.Form object, which was passed from our client side. And then, used the Windows Azure SDK to create a blob container (in this case we will use the container named “test”.) and create a blob reference with the blob name (same as the file name). Then uploaded the chunk as a block of this blob with the index, since in Blob Storage each block must have an index (ID) associated with so that finally we can put all blocks as one blob by specifying their block ID list. 1: [HttpPost] 2: public JsonResult UploadInFormData() 3: { 4: var error = string.Empty; 5: try 6: { 7: var name = Request.Form["name"]; 8: var index = int.Parse(Request.Form["index"]); 9: var file = Request.Files[0]; 10: var id = Convert.ToBase64String(BitConverter.GetBytes(index)); 11: 12: var container = _client.GetContainerReference("test"); 13: container.CreateIfNotExists(); 14: var blob = container.GetBlockBlobReference(name); 15: blob.PutBlock(id, file.InputStream, null); 16: } 17: catch (Exception e) 18: { 19: error = e.ToString(); 20: } 21: 22: return new JsonResult() 23: { 24: Data = new 25: { 26: success = string.IsNullOrWhiteSpace(error), 27: error = error 28: } 29: }; 30: } Next, I created another action to commit the blocks into blob once all chunks had been uploaded. Similarly, I retrieved the blob name from the Request.Form. I also retrieved the chunks ID list, which is the block ID list from the Request.Form in a string format, split them as a list, then invoked the BlockBlob.PutBlockList method. After that our blob will be shown in the container and ready to be download. 1: [HttpPost] 2: public JsonResult Commit() 3: { 4: var error = string.Empty; 5: try 6: { 7: var name = Request.Form["name"]; 8: var list = Request.Form["list"]; 9: var ids = list 10: .Split(',') 11: .Where(id => !string.IsNullOrWhiteSpace(id)) 12: .Select(id => Convert.ToBase64String(BitConverter.GetBytes(int.Parse(id)))) 13: .ToArray(); 14: 15: var container = _client.GetContainerReference("test"); 16: container.CreateIfNotExists(); 17: var blob = container.GetBlockBlobReference(name); 18: blob.PutBlockList(ids); 19: } 20: catch (Exception e) 21: { 22: error = e.ToString(); 23: } 24: 25: return new JsonResult() 26: { 27: Data = new 28: { 29: success = string.IsNullOrWhiteSpace(error), 30: error = error 31: } 32: }; 33: } Now we finished all code we need. The whole process of uploading would be like this below. Below is the full client side JavaScript code. 1: <script type="text/javascript" src="~/Scripts/async.js"></script> 2: <script type="text/javascript"> 3: $(function () { 4: $("#upload_button_blob").click(function () { 5: // assert the browser support html5 6: if (window.File && window.Blob && window.FormData) { 7: alert("Your brwoser is awesome, let's rock!"); 8: } 9: else { 10: alert("Oh man plz update to a modern browser before try is cool stuff out."); 11: return; 12: } 13: 14: // start to upload each files in chunks 15: var files = $("#upload_files")[0].files; 16: for (var i = 0; i < files.length; i++) { 17: var file = files[i]; 18: var fileSize = file.size; 19: var fileName = file.name; 20: 21: // calculate the start and end byte index for each blocks(chunks) 22: // with the index, file name and index list for future using 23: var blockSizeInKB = $("#block_size").val(); 24: var blockSize = blockSizeInKB * 1024; 25: var blocks = []; 26: var offset = 0; 27: var index = 0; 28: var list = ""; 29: while (offset < fileSize) { 30: var start = offset; 31: var end = Math.min(offset + blockSize, fileSize); 32: 33: blocks.push({ 34: name: fileName, 35: index: index, 36: start: start, 37: end: end 38: }); 39: list += index + ","; 40: 41: offset = end; 42: index++; 43: } 44: 45: // define the function array and push all chunk upload operation into this array 46: var putBlocks = []; 47: blocks.forEach(function (block) { 48: putBlocks.push(function (callback) { 49: // load blob based on the start and end index for each chunks 50: var blob = file.slice(block.start, block.end); 51: // put the file name, index and blob into a temporary from 52: var fd = new FormData(); 53: fd.append("name", block.name); 54: fd.append("index", block.index); 55: fd.append("file", blob); 56: // post the form to backend service (asp.net mvc controller action) 57: $.ajax({ 58: url: "/Home/UploadInFormData", 59: data: fd, 60: processData: false, 61: contentType: "multipart/form-data", 62: type: "POST", 63: success: function (result) { 64: if (!result.success) { 65: alert(result.error); 66: } 67: callback(null, block.index); 68: } 69: }); 70: }); 71: }); 72: 73: // invoke the functions one by one 74: // then invoke the commit ajax call to put blocks into blob in azure storage 75: async.series(putBlocks, function (error, result) { 76: var data = { 77: name: fileName, 78: list: list 79: }; 80: $.post("/Home/Commit", data, function (result) { 81: if (!result.success) { 82: alert(result.error); 83: } 84: else { 85: alert("done!"); 86: } 87: }); 88: }); 89: } 90: }); 91: }); 92: </script> And below is the full ASP.NET MVC controller code. 1: public class HomeController : Controller 2: { 3: private CloudStorageAccount _account; 4: private CloudBlobClient _client; 5: 6: public HomeController() 7: : base() 8: { 9: _account = CloudStorageAccount.Parse(CloudConfigurationManager.GetSetting("DataConnectionString")); 10: _client = _account.CreateCloudBlobClient(); 11: } 12: 13: public ActionResult Index() 14: { 15: ViewBag.Message = "Modify this template to jump-start your ASP.NET MVC application."; 16: 17: return View(); 18: } 19: 20: [HttpPost] 21: public JsonResult UploadInFormData() 22: { 23: var error = string.Empty; 24: try 25: { 26: var name = Request.Form["name"]; 27: var index = int.Parse(Request.Form["index"]); 28: var file = Request.Files[0]; 29: var id = Convert.ToBase64String(BitConverter.GetBytes(index)); 30: 31: var container = _client.GetContainerReference("test"); 32: container.CreateIfNotExists(); 33: var blob = container.GetBlockBlobReference(name); 34: blob.PutBlock(id, file.InputStream, null); 35: } 36: catch (Exception e) 37: { 38: error = e.ToString(); 39: } 40: 41: return new JsonResult() 42: { 43: Data = new 44: { 45: success = string.IsNullOrWhiteSpace(error), 46: error = error 47: } 48: }; 49: } 50: 51: [HttpPost] 52: public JsonResult Commit() 53: { 54: var error = string.Empty; 55: try 56: { 57: var name = Request.Form["name"]; 58: var list = Request.Form["list"]; 59: var ids = list 60: .Split(',') 61: .Where(id => !string.IsNullOrWhiteSpace(id)) 62: .Select(id => Convert.ToBase64String(BitConverter.GetBytes(int.Parse(id)))) 63: .ToArray(); 64: 65: var container = _client.GetContainerReference("test"); 66: container.CreateIfNotExists(); 67: var blob = container.GetBlockBlobReference(name); 68: blob.PutBlockList(ids); 69: } 70: catch (Exception e) 71: { 72: error = e.ToString(); 73: } 74: 75: return new JsonResult() 76: { 77: Data = new 78: { 79: success = string.IsNullOrWhiteSpace(error), 80: error = error 81: } 82: }; 83: } 84: } And if we selected a file from the browser we will see our application will upload chunks in the size we specified to the server through ajax call in background, and then commit all chunks in one blob. Then we can find the blob in our Windows Azure Blob Storage. Optimized by Parallel Upload In previous example we just uploaded our file in chunks. This solved the problem that ASP.NET MVC request content size limitation as well as the Windows Azure load balancer timeout. But it might introduce the performance problem since we uploaded chunks in sequence. In order to improve the upload performance we could modify our client side code a bit to make the upload operation invoked in parallel. The good news is that, “async.js” library provides the parallel execution function. If you remembered the code we invoke the service to upload chunks, it utilized “async.series” which means all functions will be executed in sequence. Now we will change this code to “async.parallel”. This will invoke all functions in parallel. 1: $("#upload_button_blob").click(function () { 2: // assert the browser support html5 3: ... ... 4: // start to upload each files in chunks 5: var files = $("#upload_files")[0].files; 6: for (var i = 0; i < files.length; i++) { 7: var file = files[i]; 8: var fileSize = file.size; 9: var fileName = file.name; 10: // calculate the start and end byte index for each blocks(chunks) 11: // with the index, file name and index list for future using 12: ... ... 13: // define the function array and push all chunk upload operation into this array 14: ... ... 15: // invoke the functions one by one 16: // then invoke the commit ajax call to put blocks into blob in azure storage 17: async.parallel(putBlocks, function (error, result) { 18: var data = { 19: name: fileName, 20: list: list 21: }; 22: $.post("/Home/Commit", data, function (result) { 23: if (!result.success) { 24: alert(result.error); 25: } 26: else { 27: alert("done!"); 28: } 29: }); 30: }); 31: } 32: }); In this way all chunks will be uploaded to the server side at the same time to maximize the bandwidth usage. This should work if the file was not very large and the chunk size was not very small. But for large file this might introduce another problem that too many ajax calls are sent to the server at the same time. So the best solution should be, upload the chunks in parallel with maximum concurrency limitation. The code below specified the concurrency limitation to 4, which means at the most only 4 ajax calls could be invoked at the same time. 1: $("#upload_button_blob").click(function () { 2: // assert the browser support html5 3: ... ... 4: // start to upload each files in chunks 5: var files = $("#upload_files")[0].files; 6: for (var i = 0; i < files.length; i++) { 7: var file = files[i]; 8: var fileSize = file.size; 9: var fileName = file.name; 10: // calculate the start and end byte index for each blocks(chunks) 11: // with the index, file name and index list for future using 12: ... ... 13: // define the function array and push all chunk upload operation into this array 14: ... ... 15: // invoke the functions one by one 16: // then invoke the commit ajax call to put blocks into blob in azure storage 17: async.parallelLimit(putBlocks, 4, function (error, result) { 18: var data = { 19: name: fileName, 20: list: list 21: }; 22: $.post("/Home/Commit", data, function (result) { 23: if (!result.success) { 24: alert(result.error); 25: } 26: else { 27: alert("done!"); 28: } 29: }); 30: }); 31: } 32: }); Summary In this post we discussed how to upload files in chunks to the backend service and then upload them into Windows Azure Blob Storage in blocks. We focused on the frontend side and leverage three new feature introduced in HTML 5 which are - File.slice: Read part of the file by specifying the start and end byte index. - Blob: File-like interface which contains the part of the file content. - FormData: Temporary form element that we can pass the chunk alone with some metadata to the backend service. Then we discussed the performance consideration of chunk uploading. Sequence upload cannot provide maximized upload speed, but the unlimited parallel upload might crash the browser and server if too many chunks. So we finally came up with the solution to upload chunks in parallel with the concurrency limitation. We also demonstrated how to utilize “async.js” JavaScript library to help us control the asynchronize call and the parallel limitation. Regarding the chunk size and the parallel limitation value there is no “best” value. You need to test vary composition and find out the best one for your particular scenario. It depends on the local bandwidth, client machine cores and the server side (Windows Azure Cloud Service Virtual Machine) cores, memory and bandwidth. Below is one of my performance test result. The client machine was Windows 8 IE 10 with 4 cores. I was using Microsoft Cooperation Network. The web site was hosted on Windows Azure China North data center (in Beijing) with one small web role (1.7GB 1 core CPU, 1.75GB memory with 100Mbps bandwidth). The test cases were - Chunk size: 512KB, 1MB, 2MB, 4MB. - Upload Mode: Sequence, parallel (unlimited), parallel with limit (4 threads, 8 threads). - Chunk Format: base64 string, binaries. - Target file: 100MB. - Each case was tested 3 times. Below is the test result chart. Some thoughts, but not guidance or best practice: - Parallel gets better performance than series. - No significant performance improvement between parallel 4 threads and 8 threads. - Transform with binaries provides better performance than base64. - In all cases, chunk size in 1MB - 2MB gets better performance. Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

Read the article

Problem with PXE boot

- by user70523

Hi, I followed the following link for PXE boot, http://www.howtoforge.com/setting-up-a-pxe-install-server-on-ubuntu-9.10-p3 and I was able to ping the client from the server and also when I booted up the client It is getting the IP address from the server. But later,I got this error PXELinux 3.82 2009-06-09 . . . [other informations] !PXE Entry point found (we hope) at 9D3B:0109 via plan A UNDI code segment at 9D3B len 16C2 UNDI data segment at 933B len A000 Getting cached packet 01 02 03 . . . [other informations] TFTP prefix: Trying to load: pxelinux.cfg/ec5db4c0-74fe-d511-b9e7-3d9235afe5a1 Trying to load: pxelinux.cfg/01-00-17-31-b6-5e-a8 Trying to load: pxelinux.cfg/0A64491E Trying to load: pxelinux.cfg/0A64491 Trying to load: pxelinux.cfg/0A6449 Trying to load: pxelinux.cfg/0A644 Trying to load: pxelinux.cfg/0A64 Trying to load: pxelinux.cfg/0A6 Trying to load: pxelinux.cfg/0A Trying to load: pxelinux.cfg/0 Trying to load: pxelinux.cfg/default Unable to locate configuration file Boot failed: press a key to retry or wait for reset I have put all the files mentioned in the link in tftpboot. Can anyone explain what could be the problem. Thanks in advance

Read the article

PXE boot -- kernel not found on TFTP server

- by user70523

I followed the following link for PXE boot, http://www.howtoforge.com/setting-up-a-pxe-install-server-on-ubuntu-9.10-p3 and I was able to ping the client from the server and also when I booted up the client It is getting the IP address from the server. But later,I got this error PXELinux 3.82 2009-06-09 . . . [other informations] !PXE Entry point found (we hope) at 9D3B:0109 via plan A UNDI code segment at 9D3B len 16C2 UNDI data segment at 933B len A000 Getting cached packet 01 02 03 . . . [other informations] TFTP prefix: Trying to load: pxelinux.cfg/ec5db4c0-74fe-d511-b9e7-3d9235afe5a1 Trying to load: pxelinux.cfg/01-00-17-31-b6-5e-a8 Trying to load: pxelinux.cfg/0A64491E Trying to load: pxelinux.cfg/0A64491 Trying to load: pxelinux.cfg/0A6449 Trying to load: pxelinux.cfg/0A644 Trying to load: pxelinux.cfg/0A64 Trying to load: pxelinux.cfg/0A6 Trying to load: pxelinux.cfg/0A Trying to load: pxelinux.cfg/0 Trying to load: pxelinux.cfg/default Unable to locate configuration file Boot failed: press a key to retry or wait for reset I have put all the files mentioned in the link in tftpboot. Can anyone explain what could be the problem. Thanks in advance

Read the article

Problem with PXE boot

- by user70523

I followed the following link for PXE boot, http://www.howtoforge.com/setting-up-a-pxe-install-server-on-ubuntu-9.10-p3 and I was able to ping the client from the server and also when I booted up the client It is getting the IP address from the server. But later,I got this error PXELinux 3.82 2009-06-09 . . . [other informations] !PXE Entry point found (we hope) at 9D3B:0109 via plan A UNDI code segment at 9D3B len 16C2 UNDI data segment at 933B len A000 Getting cached packet 01 02 03 . . . [other informations] TFTP prefix: Trying to load: pxelinux.cfg/ec5db4c0-74fe-d511-b9e7-3d9235afe5a1 Trying to load: pxelinux.cfg/01-00-17-31-b6-5e-a8 Trying to load: pxelinux.cfg/0A64491E Trying to load: pxelinux.cfg/0A64491 Trying to load: pxelinux.cfg/0A6449 Trying to load: pxelinux.cfg/0A644 Trying to load: pxelinux.cfg/0A64 Trying to load: pxelinux.cfg/0A6 Trying to load: pxelinux.cfg/0A Trying to load: pxelinux.cfg/0 Trying to load: pxelinux.cfg/default Unable to locate configuration file Boot failed: press a key to retry or wait for reset I have put all the files mentioned in the link in tftpboot. Can anyone explain what could be the problem. Thanks in advance

Read the article

Why do I often have to refresh pages I navigate to once for them (or content in them) to load?

- by GetOutOfBox

I have noticed a bizarre pattern when using my PC, that when I open a link to a website, it often will often take a very long time to load, or time out. Sometimes content on the website will be drawn, but again, it seems to get "stuck" for an unusual amount of time before finishing. Most affected is Youtube; almost every time I navigate to a youtube video from another website such as Google, the video will not begin playing, but will instead just display the player controls with a black screen where the video should be and the buffering symbol, usually before displaying an error such as "The video failed to load". The unusual part of this problem is that whenever this happens, refreshing the page always causes it to load almost immediately the second time around, without any problems. Note that I'm not talking about how some browsers will dump whatever has been cached to the "pallet" briefly when the page is refreshed or loading stopped; but that the second time loading the website being faster. I have done my best to rule out some of the obvious causes: My Windows 7 desktop computer is the only device that seems to be affected. I use Firefox on it (latest version, flash updated, etc). My connection has more than enough bandwidth (30 megabits down, 4 up), and I've even tried QoSing all other devices to make sure this isn't happening due to usage spikes. Wireshark is not showing any clearly unusual network activity (i.e frequently dropped packets).

Read the article

How to have SSL on Amazon Elastic Load Balancer with a Gunicorn EC2 server?

- by Riegie Godwin

I'm a self taught back end engineer so I'm learning all of this stuff as I go along. For the longest time, I've been using basic authentication for my users. Many developers are advising against this approach since each request will contain the username & password in clear text. Anyone with the right skills can sniff on the connection between my iOS application and my Django/Gunicorn Server and obtain their password. I wouldn't want to put my user's credentials at risk so I would like to implement a more secure way of authentication. SSL seems to be the most viable option. My server doesn't serve any static content or anything crazy of that sort. All the server does is send and receive "json" responses from and to my iOS application. Here is my current topology. iOS application ------ Amazon Elastic Load Balancer ------- EC2 Instances running HTTP Gunicorn. Gunicorn runs on port 8000. I have a CNAME record from GoDaddy for the Amazon Elastic Load Balancer DNS. So instead of using the long DNS to make requests, I just use server.example.com. To interact with my servers I send and receive requests to server.example.com:8000/ This setup works and has been solid. However I need to have a more secure way. I would like to setup SSL between my iOS application and my Elastic Load Balancer. How can I go about doing this? Since I am only sending json responses to my application, do I really need to buy a certificate from a CA or can I create my own? (since browsers will not be interacting with my servers. My servers are only designed to send json responses to my iOS application).

Read the article

How to make an "import image" button/field in a PDF form?

- by Joe

How to make an "import image" button/field in a PDF form? I am designing a "Lost Pet" poster for a local animal shelter. The idea is to make a PDF file that users of the shelter's website can download, insert their pet's information, and then print it out if their pet goes missing. I will be designing the poster in InDesign CS3, and then exporting it to a PDF file. I will then add form fields for the user to fill out. I am ok with making text entry form fields. That is a simple matter. What's not so simple is figuring out a way to allow the user to insert a photo of their lost pet into the PDF, save the file, and then print it out with the photo in it. I am running Adobe Acrobat Professional 8. I am running it on a Mac. All of the searches I've done have told me that if I was running Acrobat in Windows, I'd have access to this other program called LiveCycle Designer which has pre-built form item libraries, including a Image Field. But I cannot find any similar option on the Mac version. Has anyone has any experience doing something like this? If so, I could certainly use some tips on making this work. Just a quick clarification... This is a volunteer design project that I am doing for the shelter, so I don't want to spend money on any extra software/addons at all. I am hoping this can be done somehow with the pre-existing software I have.

Read the article

Load is 0, yet site crawls (sometimes). What gives?

- by Yegor

I have a ~1.5-2mil page views per day site running on 2 servers. One for mysql, other for everything else. Mysql box has a load of 3, frontend is usually 0.0-0.1. Both are dual quad core with 8GB ram running SAS drives in raid5. CPU is idle for majority of the time, iowait is non-existent. Im running nginx, memcache, and site is built on php. Half the time everything runs perfect, while at other times it lags something severe, when it takes 10-15 seconds for a page to load. Page execution time is always super low, but it seems to hang, waiting for something before it actually loads the page. Whats even more weird is that it only happens to 1 file on the site (but its the one thats most commonly accessed, that actually loads the content on the site). Other pages are super fast at all times, even when it takes 15 seconds to load actual content. I have nginx_stats plugin installed, and if I monitor it, the lag spikes happen when the write column starts going above 100, and it frequently does... all the way to 500-1000. It does so at totally random times... not when traffic is heavy... it can do this in the middle of the night, and work perfectly at 5pm when traffic is at its highest. Any ideas?

Read the article

With a jquery modular dialog how do I stop the form values from persisting?

- by stormist

(Citing source at: http://jqueryui.com/demos/dialog/#modal-form) As an example, this works great but each time the form is subsequently opened the user entered values remain. How can I stop this behavior? (the form will be used multiple times on the same page. <style type="text/css"> body { font-size: 62.5%; } label, input { display:block; } input.text { margin-bottom:12px; width:95%; padding: .4em; } fieldset { padding:0; border:0; margin-top:25px; } h1 { font-size: 1.2em; margin: .6em 0; } div#users-contain { width: 350px; margin: 20px 0; } div#users-contain table { margin: 1em 0; border-collapse: collapse; width: 100%; } div#users-contain table td, div#users-contain table th { border: 1px solid #eee; padding: .6em 10px; text-align: left; } .ui-dialog .ui-state-error { padding: .3em; } .validateTips { border: 1px solid transparent; padding: 0.3em; } </style> <script type="text/javascript"> $(function() { // a workaround for a flaw in the demo system (http://dev.jqueryui.com/ticket/4375), ignore! $("#dialog").dialog("destroy"); var name = $("#name"), email = $("#email"), password = $("#password"), allFields = $([]).add(name).add(email).add(password), tips = $(".validateTips"); function updateTips(t) { tips .text(t) .addClass('ui-state-highlight'); setTimeout(function() { tips.removeClass('ui-state-highlight', 1500); }, 500); } function checkLength(o,n,min,max) { if ( o.val().length > max || o.val().length < min ) { o.addClass('ui-state-error'); updateTips("Length of " + n + " must be between "+min+" and "+max+"."); return false; } else { return true; } } function checkRegexp(o,regexp,n) { if ( !( regexp.test( o.val() ) ) ) { o.addClass('ui-state-error'); updateTips(n); return false; } else { return true; } } $("#dialog-form").dialog({ autoOpen: false, height: 300, width: 350, modal: true, buttons: { 'Create an account': function() { var bValid = true; allFields.removeClass('ui-state-error'); bValid = bValid && checkLength(name,"username",3,16); bValid = bValid && checkLength(email,"email",6,80); bValid = bValid && checkLength(password,"password",5,16); bValid = bValid && checkRegexp(name,/^[a-z]([0-9a-z_])+$/i,"Username may consist of a-z, 0-9, underscores, begin with a letter."); // From jquery.validate.js (by joern), contributed by Scott Gonzalez: http://projects.scottsplayground.com/email_address_validation/ bValid = bValid && checkRegexp(email,/^((([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-\x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(\x22)))@((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?$/i,"eg. [email protected]"); bValid = bValid && checkRegexp(password,/^([0-9a-zA-Z])+$/,"Password field only allow : a-z 0-9"); if (bValid) { $('#users tbody').append('<tr>' + '<td>' + name.val() + '</td>' + '<td>' + email.val() + '</td>' + '<td>' + password.val() + '</td>' + '</tr>'); $(this).dialog('close'); } }, Cancel: function() { $(this).dialog('close'); } }, close: function() { allFields.val('').removeClass('ui-state-error'); } }); $('#create-user') .button() .click(function() { $('#dialog-form').dialog('open'); }); }); </script> <div class="demo"> <div id="dialog-form" title="Create new user"> <p class="validateTips">All form fields are required.</p> <form> <fieldset> <label for="name">Name</label> <input type="text" name="name" id="name" class="text ui-widget-content ui-corner-all" /> <label for="email">Email</label> <input type="text" name="email" id="email" value="" class="text ui-widget-content ui-corner-all" /> <label for="password">Password</label> <input type="password" name="password" id="password" value="" class="text ui-widget-content ui-corner-all" /> </fieldset> </form> </div> <div id="users-contain" class="ui-widget"> <h1>Existing Users:</h1> <table id="users" class="ui-widget ui-widget-content"> <thead> <tr class="ui-widget-header "> <th>Name</th> <th>Email</th> <th>Password</th> </tr> </thead> <tbody> <tr> <td>John Doe</td> <td>[email protected]</td> <td>johndoe1</td> </tr> </tbody> </table> </div> <button id="create-user">Create new user</button> </div> <div class="demo-description"> <p>Use a modal dialog to require that the user enter data during a multi-step process. Embed form markup in the content area, set the <code>modal</code> option to true, and specify primary and secondary user actions with the <code>buttons</code> option.</p> </div>

Read the article

Alternative way of developing for ASP.NET to WebForms - Any problems with this?

- by John

So I have been developing in ASP.NET WebForms for some time now but often get annoyed with all the overhead (like ViewState and all the JavaScript it generates), and the way WebForms takes over a lot of the HTML generation. Sometimes I just want full control over the markup and produce efficient HTML of my own so I have been experimenting with what I like to call HtmlForms. Essentially this is using ASP.NET WebForms but without the form runat="server" tag. Without this tag, ASP.NET does not seem to add anything to the page at all. From some basic tests it seems that it runs well and you still have the ability to use code-behind pages, and many ASP.NET controls such as repeaters. Of course without the form runat="server" many controls won't work. A post at Enterprise Software Development lists the controls that do require the tag. From that list you will see that all of the form elements like TextBoxes, DropDownLists, RadioButtons, etc cannot be used. Instead you use normal HTML form controls. But how do you access these HTML controls from the code behind? Retrieving values on post back is easy, you just use Request.QueryString or Request.Form. But passing data to the control could be a little messy. Do you use a ASP.NET Literal control in the value field or do you use <%= value % in the markup page? I found it best to add runat="server" to my HTML controls and then you can access the control in your code-behind like this: ((HtmlInputText)txtName).Value = "blah"; Here's a example that shows what you can do with a textbox and drop down list: Default.aspx <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="NoForm.Default" %> <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="NoForm.Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title></title> </head> <body> <form action="" method="post"> <label for="txtName">Name:</label> <input id="txtName" name="txtName" runat="server" /><br /> <label for="ddlState">State:</label> <select id="ddlState" name="ddlState" runat="server"> <option value=""></option> </select><br /> <input type="submit" value="Submit" /> </form> </body> </html> Default.aspx.cs using System; using System.Web.UI.HtmlControls; using System.Web.UI.WebControls; namespace NoForm { public partial class Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { //Default values string name = string.Empty; string state = string.Empty; if (Request.RequestType == "POST") { //If form submitted (post back) name = Request.Form["txtName"]; state = Request.Form["ddlState"]; //Server side form validation would go here //and actions to process form and redirect } ((HtmlInputText)txtName).Value = name; ((HtmlSelect)ddlState).Items.Add(new ListItem("ACT")); ((HtmlSelect)ddlState).Items.Add(new ListItem("NSW")); ((HtmlSelect)ddlState).Items.Add(new ListItem("NT")); ((HtmlSelect)ddlState).Items.Add(new ListItem("QLD")); ((HtmlSelect)ddlState).Items.Add(new ListItem("SA")); ((HtmlSelect)ddlState).Items.Add(new ListItem("TAS")); ((HtmlSelect)ddlState).Items.Add(new ListItem("VIC")); ((HtmlSelect)ddlState).Items.Add(new ListItem("WA")); if (((HtmlSelect)ddlState).Items.FindByValue(state) != null) ((HtmlSelect)ddlState).Value = state; } } } As you can see, you have similar functionality to ASP.NET server controls but more control over the final markup, and less overhead like ViewState and all the JavaScript ASP.NET adds. Interestingly you can also use HttpPostedFile to handle file uploads using your own input type="file" control (and necessary form enctype="multipart/form-data"). So my question is can you see any problems with this method, and any thoughts on it's usefulness? I have further details and tests on my blog.

Search Results

Search found 34922 results on 1397 pages for 'form load'.

Page 228/1397 | < Previous Page | 224 225 226 227 228 229 230 231 232 233 234 235 | Next Page >

- by ven

- by beatsforthemind

- by Rick Strahl

- by dwahlin

- by dwahlin

- by Necessary

- by Cocoa Dev

- by Mehdi Bugnard

- by krislankford

- by Rand Mate

- by MargaretW

- by Usagi

- by Justin

- by Oliver Hyde

- by Sam M

- by Shaun

- by user70523

- by user70523

- by user70523

- by GetOutOfBox

- by Riegie Godwin

- by Joe

- by Yegor

- by stormist

- by John

< Previous Page | 224 225 226 227 228 229 230 231 232 233 234 235 | Next Page >