What is the Same Origin Policy, and how does it affect GWT?
Modern browsers implement a security model known as the Same Origin Policy (SOP). Conceptually, it is very simple, but the limitations it applies to JavaScript applications can be quite subtle. Simply stated, the SOP states that JavaScript code running on a web page may not interact with any resource not originating from the same web site. The reason this security policy exists is to prevent malicious web coders from creating pages that steal web users’ information or compromise their privacy. While very necessary, this policy also has the side effect of making web developers’ lives difficult. It’s important to note that the SOP issues described below are not specific to GWT; they are true of any AJAX application or framework. This FAQ simply details the specific ways in which GWT is affected by this universal limitation.
