tcp/udp: 9528

 +---------+            +---------+                     +-----------+
 | Client  |            | Server  |                     | Metronome |
 +---------+            +---------+                     +-----------+
      |                      |                                |
      | Service Request      |                                |
      |--------------------->|                                |
      |                      |                                |
      |                      | Query user request times       |
      |                      |------------------------------->|
      |                      |                                |
      |                      |           return request times |
      |                      |<-------------------------------|
      |                      | /--------------                |
      |                      | | check quota |                |
      |                      | --------------/                |
      |                      |                                |
      |       accept or deny |                                |
      |<---------------------|                                |
      |                      |                                |

input: key ttl idstr<\n>
result: count idstr

-------------------------------------------
> uid=123,api=run 3 requestid=100
< 1 requestid=100

> uid=123,api=run 3 requestid=101
< 2 requestid=101

> uid=123,api=run 3 requestid=102
< 3 requestid=102

> uid=123,api=run 3 requestid=103
< 4 requestid=103

... 3 seconds...

> uid=123,api=run 3 requestid=104
< 1 requestid=104