ajax跨域 理解来说说

ajax跨域 懂得来说说!
这个说的跨域是访问其他工程的webservice接口?
还是直接访问其他工程的地址?

有小例子吗  简单介绍下!


------解决方案--------------------
跨域,不在同一域名空间下。
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-
transitional.dtd">
<html>    
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=gb2312">
        <title>
            查询
        </title>
        <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js">
        </script>
        <script type="text/javascript">
            jQuery(document).ready(function() {
                $.ajax({
                    type: "get",
                    async: false,
                    data: {
                        
                    },
                    url: "http://api.btctrade.com/api/ticker",
                    dataType: "jsonp",
                    jsonp: "callback",
                    success: function(json) {
                        var data = json;
                        for (var e in data) {
                            alert(e + "--->" + data[e])
                        }
                    },
                    error: function(XMLHttpRequest, textStatus, errorThrown) {
                        alert(XMLHttpRequest.status);
                        alert(XMLHttpRequest.readyState);
                        alert(textStatus);
                    }

                });

            });
        </script>
    </head>
    
    <body>
        <a href="#" id="test_post">
            查询
        </a>
    </body>

</html>

------解决方案--------------------
http://justcoding.iteye.com/blog/1366102