Amazon is adding a Cross-Origin Resource Sharing capability to its S3 Simple Storage Service, allowing developers to more easily build web applications that access data stored in the company's cloud.

Developers can now implement HTML5-based drag and drop uploads to Amazon S3, show upload progress, or update content, according to Amazon. Until now, developers needed to run a custom proxy server between their web application and S3 to support these capabilities, which made it more complicated, it said.

Cross-Origin Resource Sharing (CORS) allows developers to build web applications that make requests to domains other than the one that supplied the primary content. External web pages, style sheets, and HTML5 applications hosted in different domains can now use web fonts and images stored in S3, allowing those resources to be used across multiple web sites.

System administration staff and developers can use Amazon's Management Console or the S3 API (application programming interface) to configure an S3 bucket for CORS.

To be able to use cross-origin requests, developers have to create a so-called CORS configuration, an XML document with rules that identify what can access an S3 bucket. Developers can add up to 100 rules to the configuration document, Amazon wrote in the S3 developer guide.

Storing data in S3 using Amazon's standard offering costs from US$0.125 per gigabyte per month for the first 1TB of data, and Amazon also offers a cheaper reduced redundancy option. In addition, users must pay for requests and data transfer from Amazon's cloud.

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