What is this cloud thing?

What does ‘the cloud’ mean?
Typically, the cloud refers to web services that
fall in to one of the following categories:
• Software as a Service (SaaS)
• Platform as a Service (PaaS)
• Infrastructure as a Service (IaaS)

What is. . .

Software as a Service (SaaS)?
The applications that you access on the web.
Examples include:
• Salesforce
• Google Docs
• SugarCRM OnDemand

Platform as a Service (PaaS)?
The application environments that developers
can write their applications in for easy
scalability, high availability, and often simple
integration with SaaS.
• Google App Engine (GAE)
• Mosso CloudSites
• SugarCRM Modules
• Microsoft Azure?

Infrastructure as a Service (IaaS)?
The web services that developers use to deploy
scalable and highly available applications.
• Amazon Web Services (AWS)
• Mosso CloudServers
• Microsoft Azure
• GoGrid

What services should I care about?
PHP developers are most likely interested in
PaaS and IaaS.
Because PaaS services are very platform-
specific, we’ll focus on the common IaaS
services.

What IaaS services are available?
IaaS services are not identical, but there are
some services that are very similar and can be
found among several cloud vendors offerings:
• Elastic Cloud Computing
• Online File Storage
• Distributed Table Storage
• Job Queue Service
• MapReduce Service

What is elastic cloud computing?
Services that provide computing environments that
can grow and shrink as needed with a few
common characteristics:
• Utility computing pricing model (pay for what you
use as you go)
• Expands or contracts manually (like Amazon EC2)
or automatically (like Google App Engine) by
creating or deleting load-balanced virtual
environments
• Can be managed with a web service API and/or
an administration GUI

What is online file storage?
Services that provide storage for files- often large
files- with the following characteristics:
• Often stored in ‘containers’ (as labeled in
Microsoft Azure) or ‘buckets’ (as labeled in
Amazon EC2)
• Provides either a directory (such as Nirvanix
IMFS) or namespace (such as S3 with its
separators) model for organizing files
• Puts the files on a Content Delivery Network
(CDN) through the basic service (Nirvanix) or a
bolt-on service (S3)

What is a distributed table database?
Sometimes called document-oriented
databases, distributed table DB’s are much more
scalable than relational databases, typically with
the following characteristics:
• Joins are typically not allowed (Azure Storage
Table, Amazon SimpleDB, Intuit QuickBase, etc.)
• There is no fixed schema; fields can be added or
deleted at runtime (Again, pretty much all of
them)
• Eventual consistency

What is a simple job queue?
A very basic queue used to communicate between
machines:
• Messages often convey some unit of work for the
receiving machine to perform
• Transactions are not supported; messages are
distributed among machines using a visibility
timeout (both Amazon SQS and Window Azure
Storage Queue)
• Can be managed with a web service API and/or
an administration GUI

OK, so what’s in it for me?

Why should I use the Cloud?
• Built-in Scalability
• High Availability
• Standardization of Applications across an
Organization
• Lower Capital Expenditure
• Better Application Architecture
• Security

Why shouldn’t I use the Cloud?
• Lock-in!
• Higher Operating Expenditures
• Greater TCO over the long term
• Security (again)

Where can I ask more questions?
We’re always up for new questions in the
cloudheads forums.