How Does Image Uploader Work

Image Uploader is a client-side software intended for bulk file upload. Additionally, it allows to process images and compress files before upload, send additional data along with files, and provides a rich functionality to customize its appearance (see the Image Uploader Features topic for a complete features list). An important peculiarity of Image Uploader is that it is embedded into HTML code of your web site and does not require end user to download and install it manually.

Ideologically, Image Uploader consists of two parts which implement almost similar functionality:

• ActiveX control (for Internet Explorer);
• Java applet (for Mozilla Firefox, Safari, or other browsers having Java runtime support).

To unify these parts Image Uploader includes special JavaScript API. This script determines browser type, analyzes Image Uploader settings specified on the page and loads the component (ActiveX or Java) that matches all the conditions in the best way.

The figure below demonstrates Image Uploader concepts:

When the user starts upload, Image Uploader (ActiveX control or Java applet) prepares a HTTP POST request with selected files and additional data and sends it to the server page specified by you. This page is not a part of Image Uploader; it should be written by you. You can save uploaded files to necessary folders, save the information to the database, send email notifications, and perform other necessary operations on this page. Since Image Uploader sends data to the server in HTTP POST request, you can write this upload processing page for any HTTP-compliant server platform. The Writing Server-Side Upload Code topic contains useful information about upload processing approaches and provides code samples for the most popular server platforms.

Image Uploader is a purely client-side application. So to insert it to a page you just need to post Image Uploader-related files to your web server, and then create and configure Image Uploader on the page via provided JavaScript API. See the detailed instructions on how to deploy and configure Image Uploader in Inserting Image Uploader into Web Page and Configuring Image Uploader articles respectively.

Another way to deploy Image Uploader is to use Image Uploader ASP.NET control. Using this control has three major advantages over the way described above. All you need is to embed Image Uploader ASP.NET control into your page, and the control cares about preparing client-side code, deploying ActiveX control and Java applet. The second advantage is the ability to insert and configure Image Uploader in Visual Studio designer. The next benefit is simplification of writing server-side upload script. Image Uploader ASP.NET control includes helper classes that parses POST fields and provides typed access to uploaded data via collections familiar to all ASP.NET developers. The Inserting Image Uploader ASP.NET Control into ASP.NET Page topic gives outlook on how to use Image Uploader ASP.NET control in your Web solution.

Moreover, especially for PHP developers, Image Uploader installation pack includes Image Uploader PHP library which implements almost the same functionality and offers the same advantages as the ASP.NET control. Find the detailed information about Image Uploader PHP library in the Inserting Image Uploader PHP into Page topic.