![]() ![]() In order to do is, add the following line to the head tag. After this is done we modify the default layout “Views/Shared/_Layout.cshtml” to reference our newly added JavaScript library. We start by creating a new ASP.NET MVC 3 web application and we add the file “jquery-filedrop.js” to the Scripts folder of the project. In order to implement the client side code, we will make use of jQuery and a jQuery plugin called “jquery-filedrop” that simplifies implementing drag & drop based file upload. We will create a webpage containing a simple drop area that changes of color when the user is dragging a file over the page and we will update the content of the page if the file upload was successful. In this article, I will show you how we can implement drag & drop in an ASP.NET MVC3 web application. Luckily for us, HTML5 now also supports this and it is already supported in a number of browsers (Chrome, Firefox, Safari, …). In native applications, users can interact with files by using drag and drop which is much more intuitive. Although this works without issues in all browsers, it is far from user friendly. In the past, if your application needed to provide the possibility to upload files you had to use a file selection chooser. One of the interesting new features is support for drag and drop of files. HTML5 makes it possible to develop more powerful and more user friendly web applications than we could do ever before. When WebSockets become broadly available, SignalR will make it possible for you to move away from long polling without a lot of impact on your code. But SignalR makes it possible to start developing today the web applications of tomorrow. Yes, WebSockets is technically superior and will probably give you some extra performance on your server side. ConclusionĪs I already wanted to emphasize in the title, comparing WebSockets with SignalR is pointless. This makes an upgrade to WebSockets fairly easy when your organization adopts Windows Server 2012 and your users have moved to modern browsers such as Internet Explorer 10 or recent versions of Firefox and Google Chrome. SignalR takes care of all the details and allows developers to focus on their most important task: building a great application for users.īecause SignalR abstracts the underlying communication protocol, it can both support WebSockets and patterns, such as long polling. It makes an abstraction of the long polling pattern and gives applicative developers the same illusion as their end users: a persistent two way connection between browser and web server. This long polling pattern and similar patterns give the user the illusion that a persistent two way connection exists between the browser and the web server, but it causes some unnecessary hard work for applicative developers and this is where SignalR comes in for. When the client receives back data from the server, it will immediately resend a new request to the server. The web server does not immediately sends data back to the browser, but waits until it has data to send back. With long polling, the browser sends a request for information to the web server with a huge timeout. How is this possible? Because they rely on patterns such as ‘long polling’. Many popular web applications/sits are already capable of updating their content dynamically, yet they do not rely on web sockets. When there are limitations, people become creative and are able to circumvent the issues blocking them from developing great products. A definitive technical solution is underway in the form of web sockets, but do we really need to wait until this technology is broadly supported by the browsers of most users? In my opinion, the answer should be a clear NO. The back-end must be able to update parts of a web page without user initiative. In order to start massively replacing traditional desktop applications, the web needs a new trick: two way communication between browser and server. Today, the magic word of IT vendors for this is the ‘cloud’, but in fact this shift to an application distribution system has already started some years ago. It has evolved from a pure data distribution system to an application distribution system. It has commands to GET, UPDATE, POST or DELETE data, but it is always the client (and if we ignore REST, this means in most cases the browser) who takes the initiative. If you look at the HTTP protocol you can clearly see these origins. When the web was founded, it was designed as a system to distribute and update data. ![]()
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