This is my code:
var obj = {};
        obj.DBServer = window.DBServer;
        obj.DefDB = window.DefDB;
        obj.UserName = window.User;
        obj.password = window.Pwd;

        var url = "http://192.168.1.253/MakeLocalWebservSQLConn";
        $.ajax({
            type: "POST",
            url: url,
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            data: JSON.stringify(obj),
            async: false,
            success: OnSuccesLocalSQLConn,
            error: OnLocalConnFailure
        });