[spec] UUID

[at15]

We need uuid for nodes so we can identify them

• agent generate uuid for itself to represent node + process
• central generate uuid for itself so the agent know the central is still the central is knows ...

Ref

• https://blog.kowalczyk.info/article/JyRZ/generating-good-unique-ids-in-go.html
• https://github.com/sony/sonyflake/blob/master/sonyflake.go#L133
  • it calls net package to use private ip as machine id

[at15]

one interesting that may be related to time series is, some uid allow sort by time (roughly), which could be an interesting property for time series, i.e. add a special tag to a series called create time, and series created in a close time would be closer to each other, and when query, they may often being asked together