Cloud service providers should be capable of billing automatically based on any billing cycle. But one must not ignore the pains of a cloud service provider in calculating the usage of each and every customer, applying a specified rate plan, and generating a bill. So there should be a proper mechanism in generating a statement of account or invoice/bill.

Now the challenge here is, cloud service provider has to have a continuous watch on the usage consumption of its customer(s) which may prevent from significant revenue loss. Solution towards this is a Metering component, which integrates with cloud service providers database servers / control panel /virtualization platform to collect the usage detailed records (UDRs).

Does this accurate usage collection details really facilitate in generating usage based invoices/bills? In order to do so, a flexible rating engine should be in place to rate each individual service usage. Rating engine should allow service provider to comprehensively define different price rules and measure based on the usage. So rating engine should be extensible with no restriction on units of measurement, support flat and tiered (incremental) rating schemes and also support both the prepaid and post paid scenarios.

Following are the different rate plans a cloud service provider metering and rating system should support.

Volume based rate plan: Based on the total volume (e.g.: storage space) consumption, system should support incremental slab where price per unit varies. Depending on the total usage invoices are to be generated.

Time based rate plan: Any day of the week, day of the year and time of the day are considered in order to define different rate plans (Off peak, holidays, business hours etc). And based on these parameters the usage is been calculated and the bills are generated accordingly.

Billing: Invoicing/billing process will use the charges generated from rating engine i.e. discounts and tax calculation and posting them into accounts. Billing engine should also be flexible to support prorate rules while calculating the final invoice/bill.
