Information Technology Reference
In-Depth Information
Pure Peer-to-Peer
In a pure P2P network, peers communicate directly
without a centralized authority or server. Thus,
all peers have the same capabilities in respect to
client-server functions. The index and the meta-
data of the shared files are stored locally among
all peers. The most prominent examples were
Gnutella and Kazaa, or more recently LimeWire
or Morpheus.
Napster was by far the most familiar P2P net-
work (centralized). However, there are multiple P2P
applications, lesser known to the press, but some-
times even more popular and accessed by a larger
number of users such as AOL Instant Messenger
or more recently so called LAN-parties.
comparison Between client-server
and peer-to-peer model
Table 1 compares the client-server and P2P
model along the 5 dimensions already mentioned.
In the P2P column, if not mentioned otherwise,
the arguments are applicable to both types of P2P
systems, pure and centralized P2P. The rating of
HIGH to LOW is taken from a content provider's
perspective. The rating reflects the sum of the ar-
guments in the table which are based on literature
review and expert discussions.
P2P will not replace the client-server model.
But as Table 1 shows, P2P networks provide
many advantages over the client-server model
in respect to cost of ownership and scalability
(Parameswaran, Susarla, & Whinston, 2001;
Schollmeier, 2001). Centralized P2P networks
could provide the same quality of service and
control as currently used by client-server model.
However, in terms of performance and security,
P2P networks, and especially pure P2P networks,
lack behind the client-server model. Today, P2P
networks are used on a voluntary basis and do
not follow any economical principles (Eggs et al.,
2002). If P2P networks should support business
transactions such as purchasing a music file, they
should integrate not only functionalities like the
distribution of the digital content, but information
exchange (Gehrke, Burghardt, & Schumann 2002),
billing systems, and Digital Rights Management
(Fetscherin, 2002). If content providers want to
use P2P networks for distributing their intellectual
property content, they have to overcome these
weaknesses.
Therefore we can argue that P2P networks
have a significant cost and scalability advantage
over the client server model, where the latter has a
security and performance advantage. Centralized
or mediated P2P networks (Schollmeier, 2001)
combine the benefits of both, client-server model
and pure P2P networks. Figure 2 summarizes
these findings.
Figure 2 is especially true if the centralized
P2P networks integrate DRM which enables to
overcome the challenges of pure P2P networks
in terms of security and control.
There is no unique set of characteristics through
which a client-server model and a P2P model can
be compared. Though extensive literature review
(Burghardt, & Schumann, 2002; Eggs et al., 2002;
Gehrke, Homayounfar, Wang, & Areibi, 2002;
Milojicic et al., 2002) and expert discussion, we
came up with the following five key dimensions
with which they can be compared:
•
Cost of ownership
•
Scalability
•
Performance
•
Security (in the view of peer and content
provider)
•
Quality of service / control
There are other important aspects like trust, in-
teroperability, metadata, reputation, and firewalls
(Lethin, 2001; Milojicic et al., 2001; Waldman,
Cranor, & Rubin, 2001) which are also taken into
account to some extend in this analysis as well as
business, legal, and technical challenges which
Schoder and Fischbach (2002) discussed in their
paper, as well as technical and nontechnical chal-
lenges (Milojicic et al., 2002).
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