算法名称：Backend authentication login

输入：String event, identity, password

输出：JSON格式数据

步骤1：

Log the result as "$r", verified by the "check_id" function

步骤2：

if "$r">0 then

步骤3：

Record "role" and "userID" in Local Storage

步骤4：

else

步骤5：

Clear "role" and "userID" from Local Storage

步骤6：

returnjson_encode($r)