对ORACLE中bequeath connections的理解
原文:
The following steps, which show the connection process for the bequeath
connections, are exhibited in Figure 2.1:
1.The client contacts the Oracle server after resolving the service name.
2.The server spawns a dedicated process and bequeaths control of the
connection to the process. The new process inherits all control information
of the spawned process, including the TCP/IP socket information
from the server that spawned the process.
3.The server process notifies the client to start sending information to it
by sending a RESEND packet to the client.
4.The client sends a CONNECT packet to the newly established server process.
5.The server responds back with an ACCEPT packet and now manages the client requests.

在WINDOWS平台下,默认是不产生bequeath connection的,为了产生bequeath connection,需要设置下下注册表
In order to have bequeathed sessions supported on Windows NT/2000, the
Registry setting USE_SHARED_SOCKET needs to be set. This setting can be set in
HKEY_LOCAL_MACHINE SOFTWAREORACLEHOMEX
where X is equal to the HOME that you are using, such as HOME0
. By default, this Registry setting is not
initialized and therefore Windows NT/2000 will use a redirect type connection
to establish communication when dedicated clients connections are used.

设置后要重启操作系统,而不能只重启数据库.
这样,1521端口才能被多个连接所使用,否则Server Process会随机选择一个端口,和client建立连接.不能穿过防火墙.
防火墙还有一个潜在的威胁是对于不活动的TCP连接会给你断线.网上有人因为这个原因查应用查了很长时间,结果是防火墙的原因,还被网管说他们的设计不合理.
以后的应用设计,最好是把应用服务器与数据库服务器放在一个网段中,而不是隔着网闸防火墙,可减少麻烦.

对Redirect Connections的理解

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