Hidden Nodes的用处

11.5 Hidden Nodes

In a distributed Erlang system, it is sometimes useful to connect to a node without also connecting to all other nodes. An example could be some kind of O&M functionality used to inspect the status of a system without disturbing it. For this purpose, a hidden node may be used.

A hidden node is a node started with the command line flag -hidden. Connections between hidden nodes and other nodes are not transitive, they must be set up explicitly. Also, hidden nodes does not show up in the list of nodes returned by nodes(). Instead, nodes(hidden) or nodes(connected) must be used. This means, for example, that the hidden node will not be added to the set of nodes that global is keeping track of.

This feature was added in Erlang 5.0/OTP R7.

设计的目的是减少节点见互联互通的通讯成本，不用global模块去跟踪这个节点的名字同步等。特别适合于用ei写的c程序， 因为ei是轻量的，没有这么多资源和必要去做无必须的事情。ei一般用作client, 去请求别的节点做复杂的运算！