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A Survey of Cloud Computing
Jesse Dunietz
SASS Talk
Cloud service = unified-looking, networkaccessible resource pool
On-demand selfservice
Large, homogeneous
resource pool
Ubiquitous access
over network
Room for ondemand increase
of resources
Cloud service looks like
single, localeindependent entity
Self-monitoring for
provider and
consumer
The central ideas of CC are not new.
• The grand vision: J.C.R. Licklider’s “intergalactic
computer network” (1963)
• Utility computing
•
“If computers of the kind I have advocated become the
computers of the future, then computing may someday be
organized as a public utility just as the telephone system is a
public utility…The computer utility could become the basis of
a new and important industry.”
--John McCarthy (1961)
• Mainframes  desktop computing  utility/cloud
Grid computing: an intermediate step
• Grid is “a system that:
• coordinates resources that are not subject to centralized
control
• using standard, open, general-purpose protocols and
interfaces
• to deliver nontrivial qualities of service” (--Ian Foster)
• Distributed, parallelised computation
• Loosely coupled
• Extension of clustering
• Computing as accessible as the electric grid
• E.g. Folding@Home, SETI@Home (BOINC)
Grid computing: an intermediate step
Recent years have seen an explosion of cloudlike services.
• 1999: salesforce.com
• 2002: Amazon Web Services
• 2005: Zoho Office
• 2006: Amazon EC2
• 2007: Gmail/Google Apps
• 2009: Chrome OS announced
Recent years have seen an explosion of cloudlike services.
Cloud computing depends on many recent
software technologies.
• Late 1990’s: widespread broadband Internet
• Late 1990’s: OS virtualisation
• Xen hypervisor developed at Cambridge CL!
• 2005-2006: Intel/AMD offer hardware-assisted virtualization
• Server farm management (scaling)
“As a service” (XaaS) is the new computing
paradigm.
Google Docs,
Photoshop Express
J2EE, Google App Engine
Amazon EC2, GoGrid,
Microsoft Azure
Infrastructure
Software
Platform
Cloud deployments come in all shapes and
sizes.
• Private cloud
• Public cloud
• e.g. Amazon
• Community cloud
• e.g.
http://www.scienceclouds.org
• Hybrid
CC has obstacles, but offers many benefits.
Disadvantages
Advantages
Privacy
Cost savings
Reliability
HW/OS independence ([S|I]aaS)
Migration
Server security
Legal issues
“Thin” clients for wimpy devices
Account security
Update speed
Lock-in (loss of control)
New uses for cloud technology are constantly
popping up.
• Rich web applications
• Computing as a utility (IaaS)
• New “back office”
functionality applications
• E.g. Apple Push
Notification Service
• Anywhere, anytime
computing
Not everyone’s head is in the clouds.
• A few treasures from Richard Stallman:
•
•
“[The] term [‘cloud computing’] is too nebulous to refer to anything in
particular. If it has any meaning, it can only be, ‘Don't pay attention to who
controls your data or your computing. Just trust every company.’”
“The issue I've raised is about a more specific kind of scenario: Software as a
Service. We can avoid it, and avoiding it is the only way to maintain our
freedom.”
• Another from Oracle CEO Larry Ellison:
•
Cloud computing has been defined as “everything that we currently do” and
will have no effect except to “change the wording on some of our ads”
• Recent outages reduced trust in reliability
• Greenpeace has complained about energy usage
CC is still full of unsolved problems.
• Interoperability,
generic design
blueprint
• Making sporadic self-healing
converge on consistency
• Formal models for “loose
coupling” vs. brokenness
“Everything we think of as a computer today is
really just a device that connects to the big
computer that we are all collectively building.”
-- Tim O’Reilly, CEO, O’Reilly Media