[infinispan-dev] Distributed Counter Discussion

[Eric Wittmann]

Greetings.  Apologies for coming in a bit late on this conversation. 
Tristan pointed me to it a couple of days ago and unfortunately I'm just 
now getting time to reply.

I can try to quickly give an overview of apiman's (JBoss API Management 
Gateway) requirements.

What we're trying to do is implement support for Limiting policies:

* Rate Limiting/Throttling (e.g. limit of 100 requests per second)
* Quotas (e.g. limit of 100,000,000 requests per month)
* Transfer Quotas (e.g. limit of 2.5GB of data downloaded per day)

We will need to support multiple backing implementations of the Rate 
Limiter, and we're trying to get Infinispan to be one of those 
implementations.

In no particular order, we would need the following characteristics:

- Can be "squishy" for quotas and transfer quotas:  If you
   get 100,001,017 requests that's OK
- Strict would be cool as an option:  Hard-fail when the
   counter reaches the limit - no chance it will go over.
- Lots of individual counters:  users may publish 100s of
   APIs to the Gateway, and each API may be consumed by
   100s or 1000s of users/client.  Depending on configuration
   of the policy, *each* user/client has a separate limit.
- Counters need to be created dynamically:  users can
   add APIs via the Management UI, configure them to add
   policies (e.g. a Quota policy) and then publish them to
   a running Gateway, at which point end users can invoke
   the API through the Gateway, which will use a counter
   to enforce the Quota.
- Counter values reset at the end of a time boundary:  for
   example, at the end of the month the counter value for
   the example quota above would reset to 0.
- Don't care (right now) what the counter value is: at the
   moment we simply need to know if some counter max value
   has been reached.  In the future we would like to know
   when a max value is being "approached" (e.g. to notify a
   user)
- Should be persistent: it would not be ideal for e.g. per-
   month quota values to be lost on server restart.

That's all the high level requirements I can think of off the top of my 
head, and after reading all of the current messages in this thread. :)

-Eric