def robotsrulesetOfDomain(self, domain):
		'''检查domain是否在数据库中,
			否 --> (False, None)
			是 --> (True, 数据库中存储的robots.txt内容)
		'''
		exist = False
		cur = self.conn.cursor()
		# 是否存在
		cur.execute("SELECT 1 FROM Domains WHERE domain=?", (domain,))
		if cur.fetchone() :
			exist = True
		# 存在的话,结果是什么
		cur.execute("SELECT rules FROM Domains,Rulesets "
			"WHERE domain=? AND Domains.did=Rulesets.did"
			,(domain,) )
		ruleset = cur.fetchone()
		return (exist, ruleset)
def __init__(self, orchestrator):
        """
        :param orchestrator: Orchestrator instance.
        :type orchestrator: Orchestrator
        """

        # Keep a reference to the Orchestrator.
        self.__orchestrator = orchestrator

        # Keep a reference to the global RPC map (it's faster this way).
        self.__rpcMap = rpcMap

        # Check all RPC messages have been mapped at this point.
        missing = MSG_RPC_CODES.difference(self.__rpcMap.keys())
        if missing:
            msg  = "Missing RPC implementors for codes: %s"
            msg %= ", ".join(str(x) for x in sorted(missing))
            raise SyntaxError(msg)