19-04-2013, 03:11 PM
Virtualized Screen: A Third Element for CloudMobile Convergence
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INTRODUCTION
In recent years, we have witnessed the strong
growth of cloud computing, which refers to
both applications delivered as services over
the Internet and the infrastructure (including
both hardware and software systems) in the
data centers that supports those services.1 In
general, cloud computing provides a centralized
platform where programs can be executed
and data can be stored. Cloud services built on
the platformcan offload many computing tasks
normally solely done on the client devices and
can be accessed instantly from anywhere at any
time. However, until recently, the place where
screen images that interface with users are rendered
has been mostly done locally on client
devices.
Screen in the cloud
Rapid development of the Internet has provided
opportunities for using remote computing
and storage resources hosted by powerful,
parallel, distributed machines in a public or
private data center. In a typical cloud-client
computing architecture, the data and the program
can be stored, loaded, and run remotely
and/or locally. To take advantage of the
cloud, computationally intensive tasks are usually
undertaken in the cloud to generate some
intermediate results (for example, HTML
data), which are then delivered to the clients
for the creation of a locally processed display
screen. In other words, local screen rendering
is separated from the data storage and program
execution, and is connected to them through
the Internet.
Up until now, the virtualization of the
screen in the cloud has been an underdeveloped
area in cloud computing. An even less
addressed area is how to leverage the virtual
screen in the cloud and combine it with
local rendering capabilities to give the same
or even better user experiences across different
devices, regardless of their computing capability,
rendering capability, bandwidth,
and screen resolution. Figure 1 depicts the
proposed conceptual architecture for cloud
client computing, in which the virtual screen
is rendered in the cloud. Behaving like the
data and the program, the screen can be processed
adaptively and collaboratively between
the cloud and the clients, determined by the
client and cloud capabilities.
System architecture
Thin-client, remote-computing systems are
expected to provide high-fidelity displays and
responsive interactions to end users as if they
were using local machines. However, the complicated
graphical interfaces and multimedia
applications usually present technical challenges
to thin-client developers for achieving
efficient transmissions with relatively lowbandwidth
links. Figure 2 depicts the proposed
thin-client, remote-computing system, which
decouples the application logic (remote) and
the user interface (local) for clients to use remote
servers deployed as virtual machines in
the cloud. The servers and the clients communicate
with each other over a network through
an interactive screen-remoting mechanism.
The clients send user inputs to the remote servers,
and the servers return screen updates to the
clients as a response.
Screen compression
Screen images might include, but are not
limited to, webpages, slides, posters, images,
videos, and anything showing up on your computer
screen. For natural pictures, many existing
image- and video-coding standards (such
as, JPEG2000 and H.264/Advanced Video Coding)
have demonstrated excellent coding performances.
However, they are inefficient for
compressing screen images that in most cases
contain rich text.
Cloud-mobility convergence
The rapid evolution of mobile computing
offers a wide variety of freedom to mobile
users. Besides communication functions, a
mobile device could be a computing, sensor,
control, gaming, and natural-interaction platform.
However, it’s difficult for a mobile device
to serve as a dominant device for all the user’s
computing needs, mainly because of its limited
capabilities in terms of computing, storage,
display, and interaction. On the other hand,
cloud computing offers unlimited computing
and storage capabilities through centralized
data centers.
Cloud Browser
As most mobile phones come with preinstalled
Web browsers, mobile browsing is becoming
increasingly popular. However, many
mobile browsers have limited support for complicated
HTML objects, such as full-feature
Flash, JavaScript, and Silverlight. Installation
of add-ons from some websites in many cases
isn’t possible. Even worse, the website owners
might have to develop and maintain two versions
of the same content, one full version for
desktop browsers, and the other simplified
version for mobile browsers. In most cases,
the mobile version loses rich multimedia information
and results in a compromised and
degraded browsing experience. It’s desirable to
bring the desktop-like browsing experiences to
mobile phones.
Cloud Phone
The smartphones as a personal computing
device are broadly available to mobile users.
In addition to a wide variety of phone brands
and a number of different operating systems
in the market, the rapid development of hardware
and application software accelerates the
pace at which phone hardware is upgraded. Is
it possible to replace the frequent hardware
upgrades with only software and services
upgrades? Recently, we have built a prototype
of a complete cloud-service-based phone solution,
the Cloud Phone, with which the phone
user can access the ever increasing programs
and services available in the cloud, even on a
low-cost device without the need to update
phone hardware anymore.
Conclusions
Cloud computing is not a simple extension
of Web services. Breakthroughs may come
with the introduction of a new application interface
model between the cloud and the clients.
User interaction with the cloud through
clientcloud communications bounds the user
experience and presents many technical challenges.
We have shown that advanced multimedia
compression and networking technologies
can bridge the devices and the cloud effectively
and efficiently.