How to Choose the Right Cloud - Advanced Design Approaches to Emerging Software Systems - page 227

Table 1. SaaS billing metrics

Type of
Metric

Metric Explanation Unit of measurement Charges and current SaaS

vendors

Resource metrics
Number of users Internal enterprise employees # of licences Based on ranges of # licences

www.salesforce.com
www.salesboom.com

Pay per user External community users,

potential customers

# of page views per month Based on usage per search
http://www.ppcsaas.com/
(for a Search Engine SaaS is the
number of searches per month)

Pay per concurrent
user

Systems of high concurrence # of concurrent users per

month

Teleconferecing and knowledge
sharing systems
http://www.nefsis.com

Number of user +
additional bandwidth
and storage

Low prices for small number of
users because of additional band-
width and storage charging

# of users + infrastructure
charges

Based on ranges of # number of
users + ranges of infrastructure
usage

Trasactional metrics
New Subscription Licence fees + Professional

services

Standard subscription fee,
training costs, consultancy
costs, user support costs

Subjective monetary costs by
SaaS provider

Upgrade Cost of upgrading current ap-

plication

Based on the level of
upgrade.
(time, infrastructure,
labour costs are counted)

Subjective monetary costs by
SaaS provider

Downgrade Cost of downgrading current

application

Based on the level of
degrade

Subjective monetary costs by
SaaS provider

Adjustment Cost of adjustment of current

application

Based on the level of
adjustment

Subjective monetary costs by
SaaS provider

Renewal Cost of renewing SaaS agree-

ment

Subjective monetary costs
by SaaS provider

Subjective monetary costs by
SaaS provider

Cancellation Penalty costs of cancelling a

SaaS SLA

Workflow m etrics
Succesful business
scenarios that show
the benefit of the cus-
tomer using a SaaS

Invoices (proofs of sales),
Emails (proof of marketing and
advertisment)

# business metric/ month Measure business successful

usage
http://www.verticalresponse.
com/
http://www.zoho.com/invoice/
index.html

studios that include all necessary tools to build a
web application, seamless deployment to hosted
runtime environment and management and moni-
toring tools. PaaS offers the potential for general
developers to build web applications without
having any tools installed in their own space.
PaaS applications are hosted to infrastructure of-
fered as a service by cloud computing providers.

Therefore, the costs of PaaS are connected to the
costs of Infrastructure as a Service and will be
analytically addressed in the next section.

C. Infrastructure as a Service

Infrastructure as a Service is a provision model
in which the customer outsources the equipment