Examples
of distributed systems
1.
Web
search
Global
number of searches has risen to over 10 billion per calendar month
-
The
task of a web search engine is to index the entire contents of the World
Wide Web, encompassing a wide range of information styles including web
pages, multimedia sources and (scanned) books.
-
most
search engines analyze the entire web content and then carry out
sophisticated processing on this enormous database, this task itself represents
a major challenge for distributed
systems design.
Highlights of
this infrastructure include:
·
an
underlying physical infrastructure consisting of very large numbers of
networked computers located at data centers all around the world;
• A distributed file system designed to support
very large files and heavily optimized for
the style of usage required by search
and other Google applications (especially reading
from files at high and sustained rates);
• an associated structured distributed
storage system that offers fast access to very large
datasets;
• a lock service that offers distributed
system functions such as distributed locking and
agreement;
•
a
programming model that supports the management of very large parallel and
distributed
computations across the
underlying physical infrastructure.
2.
Massively
multiplayer online games (MMOGs)
very large numbers of users interact
through the Internet with a persistent virtual world
Examples
Sony’s
EverQuest II and EVE Online
The number of
players is also rising, with systems able to support over 50,000 simultaneous online players.
Major
challenges:
-
the
need for fast response times to preserve the user experience of the game
-
real-time
propagation of events to the many players and maintaining a consistent view of
the shared world.
Solutions for
massively multiplayer online games:
-
the
largest online game, EVE Online, utilises a client-server architecture
where a single copy of the state of the world is maintained on a centralized
server and accessed by client programs running on players’ consoles or other
devices
-
The
centralized architecture helps significantly in terms of the management of
the virtual world and the single copy also eases consistency concerns.
-
to
ensure fast response through optimizing network protocols and ensuring a
rapid response to incoming events.
-
Other
MMOGs adopt more distributed architectures. Users are then dynamically
allocated a particular server based on current usage patterns and also the
network delays to the server
-
not
based on client-server principles but rather adopt completely decentralized
approaches based on peer-to-peer technology where every participant contributes
resources (storage and processing) to accommodate the game
3. Financial trading
The
financial industry has long been at the cutting edge of distributed systems
technology with its need, in particular, for real-time access to a wide range
of information sources (for example, current share prices and trends, economic
and political developments). The industry employs automated monitoring and
trading applications.
-
communication
and processing of items of interest, known as events in distributed
systems
Examples
a drop in a
share price, the release of the latest unemployment figures
-
such
systems typically employ what are known as distributed event-based systems.
No comments:
Post a Comment