This document discusses different cloud delivery models from the perspective of cloud consumers. It covers considerations for infrastructure as a service (IaaS), platform as a service (PaaS), and software as a service (SaaS). For IaaS, it describes how virtual servers can be accessed and managed. For PaaS, it outlines tools and resources for developers as well as management features. For SaaS, it notes that services usually have APIs to incorporate into other solutions and discusses customization options and responsibilities for cloud consumers.

1. 14.2. CLOUD DELIVERY MODELS: THE CLOUD
CONSUMER PERSPECTIVE
This section raises various considerations concerning the different ways in which
cloud delivery models are administered and utilized by cloud consumers.
Working with IaaS Environments
Virtual servers are accessed at the operating system level through the use of remote
terminal applications. Accordingly, the type of client software used directly
depends on the type of operating system that is running at the virtual server, of
which two common options are:
• Remote Desktop (or Remote Desktop Connection) Client – for Windows-
based environmentsand presentsa WindowsGUI desktop
• SSH Client – for Mac and other Linux-based environmentstoallow for
secure channelconnectionsto text-based shell accountsrunning onthe
server OS
Figure14.4 illustratesa typicalusagescenariofor virtualservers that are
being offered as IaaS services after having been created with management
interfaces.
A cloud storagedevicecan be attacheddirectlytothe virtualservers and
accessed through thevirtualservers’ functionalinterfacefor management
by the operating system. Alternatively, a cloud storagedevicecan be
attached toanIT resourcethat is being hosted outsideof the cloud, such as
an on-premisedeviceover a WAN or VPN. In these cases, the following

2. formatsfor the manipulationand transmissionofcloud storagedata are
commonly used:
• Networked File System –System-based storageaccess, whoserendering
of files is similar to how folders are organized in operating systems(NFS,
CIFS)
• Storage Area Network Devices –Block-based storageaccesscollates and
formatsgeographicallydiversedata intocohesive files for optimalnetwork
transmission (iSCSI, FibreChannel)
• Web-Based Resources – Object-basedstorageaccessbywhich an
interfacethat isnot integrated intotheoperating system logically
representsfiles, which canbe accessed through a Web-based interface
(AmazonS3)
IT Resource Provisioning Considerations
Cloud consumers have a high degree of control over how and to what extent IT
resources are provisioned as part of their IaaS environments.
For example:
• controlling scalabilityfeatures(automated scaling, load balancing)
• controlling the lifecycle of virtualIT resources (shutting down, restarting,
powering up of virtualdevices)
• controlling the virtualnetworkenvironment and networkaccessrules
(firewalls, logicalnetworkperimeters)
• establishing and displaying serviceprovisioning agreements(account
conditions, usageterms)
 managing theattachmentofcloud storagedevices
• managing thepre-allocationof cloud-based IT resources (resource
reservation)
• managing credentialsand passwordsfor cloud resourceadministrators
• managing credentialsfor cloud-based securitygroupsthat access
virtualized IT resourcesthrough an IAM
• managing security-related configurations
• managing customized virtualserver imagestorage(importing, exporting,
backup)
• selecting high-availabilityoptions(failover, IT resourceclustering)
• selecting and monitoring SLA metrics

3. • selecting basic softwareconfigurations(operating system, pre-installed
softwarefor new virtualservers)
• selecting IaaS resourceinstancesfrom a number of availablehardware-
related configurationsand options(processing capabilities, RAM, storage)
• selecting the geographicalregionsinwhich cloud-based IT resources
should be hosted
• tracking and managing costs
The management interfacefor these types of provisioning tasksis usually a
usageand administrationportal, but mayalso be offered via theuse of
command line interface(CLI) tools that cansimplify theexecutionof many
scripted administrativeactions.
Even though standardizingthepresentationofadministrativefeaturesand
controls is typicallypreferred, using different tools and user-interfacescan
sometimesbe justified. For example, a script canbe madeto turnvirtual
servers on and off nightly through a CLI, while adding or removing storage
capacitycanbemore easily carried out using a portal.
Working with PaaS Environments
A typical PaaS IDE can offer a wide range of tools and programming resources,
such as software libraries, class libraries, frameworks, APIs, and various runtime
capabilities that emulate the intended cloud-based deployment environment. These
features allow developers to create, test, and run application codewithin the cloud
or locally (on-premise) while using the IDE to emulate the cloud deployment
environment. Compiled or completed applications are then bundled and uploaded
to the cloud, and deployed via the ready-made environments. This deployment
process canalso be controlled through the IDE.
PaaS also allows for applicationstouse cloud storagedevicesas
independent data storing systemsfor holding development-specificdata
(for examplein a repositorythat is availableoutsideof the cloud
environment). Both SQL and NoSQL databasestructuresaregenerally
supported.
IT Resource Provisioning Considerations
PaaS environments provide less administrative control than IaaS environments, but
still offer a significant range of management features.
For example:
• establishing and displaying serviceprovisioning agreements, such as
account conditionsand usageterms

4. • selecting softwareplatform and development frameworksfor ready-made
environments
• selecting instancetypes, which are most commonly frontend or backend
instances
• selecting cloud storagedevicesfor use in ready-madeenvironments
• controlling the lifecycle of PaaS-developed applications(deployment,
starting, shutdown, restarting, and release)
• controlling the versioning of deployed applicationsand modules
• configuring availabilityand reliability-related mechanisms
• managing credentialsfor developers and cloud resourceadministrators
using IAM
• managing generalsecuritysettings, such as accessiblenetworkports
selecting and monitoring PaaS-related SLA metrics
• managing and monitoringusageand IT resourcecosts
• controlling scalabilityfeaturessuch asusagequotas, activeinstance
thresholds, and the configurationand deployment of the automated scaling
listener and load balancer mechanisms
The usageand administrationportalthat isused to access PaaS
management featurescanprovidethefeatureof pre-emptivelyselecting the
timesat which an IT resourceis started and stopped. For example, a cloud
resourceadministrator canset a cloud storagedeviceto turnitself on at
9:00AM thenturnoff twelve hours later. Building on thissystem can
enable the optionof having theready-madeenvironment self-activateupon
receiving data requestsfor a particularapplicationand turnoff after an
extended period of inactivity.
Working with SaaS Services
Because SaaS-based cloud services are almost always accompanied by refined and
generic APIs, they are usually designed to be incorporated as part of larger
distributed solutions. A common example of this is Google Maps, which offers a
comprehensive API that enables mapping information and images to be
incorporated into Web sites and Web-based applications.
ManySaaS offeringsare provided free of charge, although thesecloud
services often comewith data collecting sub-programsthat harvest usage
data for the benefit of the cloud provider. When using any SaaS product
that is sponsored by third parties, thereisa reasonablechancethat it is
performing a form of background informationgathering. Readingthecloud

5. provider’sagreement will usually help shed light on any secondaryactivity
that the cloud service is designed to perform.
Cloud consumersusing SaaS productssupplied bycloud providersare
relieved of the responsibilitiesof implementingand administeringtheir
underlying hosting environments. Customizationoptionsareusually
availableto cloud consumers; however, these optionsare generally limited
to the runtimeusagecontrolof the cloud service instancesthat are
generated specificallybyand for the cloud consumer.
For example:
• managing security-related configurations
• managing select availabilityand reliabilityoptions
• managing usagecosts
• managing user accounts, profiles, and accessauthorization
• selecting and monitoring SLAs
• setting manualand automated scalabilityoptionsand limitations