Information Technology Reference
In-Depth Information
Graphic user interface
Metadata search layer
Content manager service
JXTA platform
Physical network
Figure 12.2
Content manager service architecture.
and description. The CMS also provides a protocol based on JXTA pipes
for transferring content between peers. Unlike some other P2P systems,
peers running CMS are not required to use HTTP in order to exchange
content.
The overall architecture of our metadata-life memories sharing system
is shown in Figure 12.2. In the architecture, the JXTA platform provides
basic P2P communication mechanism, including peer discovery, pipe, and
advertisement. The content manager service built upon the JXTA platform,
implements content publication and transmission. The metadata search
layer, as could be seen from the figure, is implemented as an extended
service based on the existing content manager service, providing rich
metadata search mechanism and the general purpose query language
interface. Users manipulate the content using the graphics user interface
implemented through Java Swing API. Seeking to provide a general P2P
infrastructure across the boundaries of programming languages, plat-
forms, and network protocols, the JXTA platform implements several core
protocols based on common concepts like peer identifier, peer group, mes-
sage, advertisement, and pipe. Figure 12.3 shows the architecture of the
JXTA peer.
On the basis of the JXTA core layer, several Sun JXTA services and diverse
JXTA community services have been implemented. Among them is the
CMS, a file sharing and retrieving service that allows JXTA applications to
share and exchange content within the scope of peer groups. Topmost is the
real-world JXTA applications. They rely on the JXTA protocols and services
to meet different needs pertaining to P2P networking. This is where our
resource-sharing application lies. In a CMS, each piece of content is repre-
sented by a globally unique identifier generated by a 128-bit MD5 checksum
algorithm from the content. The content ID is utilized when comparing and
requesting content. Through the use of the content advertisement, an XML
file describing services and messages, each peer can publish its content along
