For some reason (e.g. specify an only ip for one spider in a large cluster), we need an agent and spider matching mechanism. The tags system is here for that.
Spider may has up to one tag. Agent may has many tags. A spider must be run on the agent which has its tag.
Matching rules see:
|Spider Tag, Agent Tags||None||a||b||a, b|
Tips: An agent with some tag will never match any none tag spider.