This document describes a peer-to-peer messaging system built using the JXTA platform. The system allows instant messages to be sent between peers in a decentralized JXTA network. JXTA defines protocols for peer-to-peer communication, where all peers have equal status and can request or provide services. The system includes a JXTA relay that receives commands from J2ME clients, performs actions on their behalf, and represents the clients on the JXTA network by discovering peers and routing messages. The goal of the project is to enable instant messaging between peers in a peer-to-peer manner without a centralized server.

1. Peer to Peer Messaging System
(Synopsis)
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2. ABSTRACT
The project titled
peer-to-peer Messaging presents the development
of an instant messaging application based on the concept of peer-topeer
networking
using
JXTA
platform.
P2P
(or
peer-to-peer)
networking is a network model where, depending on an operation's
context, any node can operate as either a server or a client. The P2P
architecture is a decentralized architecture, where neither client nor
server status exists in a network. Every entity in the network, referred
to as a peer, has equal status, meaning that an entity can either
request a service or provide a service. The main goal of this project is
to send instant messages to peers in the JXTA network using JXTA
relay.
JXTA defines a set of protocols to enable a framework for peerto-peer computing. All JXTA network users are peers to each other .
Peers communicate with each other to perform different tasks (such
as searching for new peers). Peer identifiers uniquely identify the peer
on the JXTA network The JXTA relay can accept client commands and
act upon the commands on the client's behalf. The relay acts as a
junction between the JXTA networks and peers.
JXTA has defined the data communication protocols that enable
messaging between a relay and a client. The JXTA relay receives
commands from a J2ME client, performs what's necessary on the
client's behalf, and represents a JXME client on the JXTA network. The
JXME client send messages to the relay. The relay discovers the peer
and route the messages to the destination.
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3. INTRODUCTION
The traditional approach to information systems,
accessed by users by means of powerful devices (such as desktops
and laptops) with known features, will not be anymore significant in
the future years. Indeed, the current trend suggests that it will be
possible to offer continuous access to all information sources, from all
locations and through various kinds of devices, mainly small and
mobile (e.g., palmtops and PDAs, cellular phones). Therefore, the need
emerges for the design of applications for smart devices, which are
highly flexible, capable of exploiting in an optimal way the resources.
This Project analyzes the opportunity to design, develop and deploy
interactive applications running on smart cellular phones (commonly
referred to as smart phones), based on a peer-to-peer communication
model and GPRS technology.
PEER-TO-PEER (P2P) TECHNOLOGY enables any
network-aware device to provide services to another network-aware
device. A device in a P2P network can provide access to any type of
resource that it has at its disposal, whether documents, storage
capacity, computing power, or even its own human operator.
In the client/server architecture, clients request services and
servers provide those services. A variety of servers exist in today's
Internet -- Web servers, mail servers, FTP servers, and so on. The
client/server architecture is an example of a centralized architecture,
where the whole network depends on central points, namely servers,
to provide services. Regardless of the number of browsers or clients,
the network can exist only if a server exists.
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4. CLIENT-SERVER MODEL
Like the client/server architecture, P2P is also a
distributed computing model, but there is an important difference. The
P2P architecture is a decentralized architecture where neither client
nor server status exists in a network. Every entity in the network,
referred to as a peer, has equal status, meaning that an entity can
either request a service (a client trait) or provide a service (a server
trait). Figure 2 illustrates a P2P network.
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5. PEER-TO-PEER MODEL
Though peers all have equal status in the network, they don't all
necessarily have equal physical capabilities. A P2P network might
consist of peers with varying capabilities, from mobile devices to
mainframes. A mobile peer might not be able to act as a server due to
its intrinsic limitations, even though the network does not restrict it in
any way.
Although P2P might sound like a dot-com fad, the
technology is a natural extension of the Internet’s philosophy of
robustness through decentralization. In the same manner that the
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6. Internet provides domain name lookup (DNS), World Wide Web, email,
and other services by spreading responsibility among millions of
servers, P2P has the capacity to power a whole new set of robust
applications by leveraging resources spread across all corners of the
Internet.
P2P networks shun the centralized organization of
the client/server architecture and instead employ a flat, highly
interconnected architecture. By allowing intermittently connected
computers to find each other, P2P enables these machines to act as
both clients and servers that can determine the services available on
the P2P network and engage those services in some application
specific manner. The main advantage of P2P networks is that they
distribute the responsibility of providing services among all peers on
the network; this eliminates service outage due to a single point of
failure and provides a more scalable solution for offering services. In
addition, P2P networks exploit
available bandwidth across the entire network by using a variety of
communication channels and by filling bandwidth to the “edge” of the
Internet. Unlike traditional client/server communications, P2P enables
communication via a variety of network routes, thereby reducing
network congestion.
P2P is the key to realizing this potential, giving
individual machines a mechanism for providing services to each other.
Unlike the client/server architecture, P2P networks don’t rely on a
centralized server to provide access to services, and they usually
operate outside the domain name system.
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7. P2P has the capability of serving resources with
high availability at a much lower cost while maximizing the use of
resources from every peer connected to the P2P network. Whereas
client/server solutions rely on the addition of costly bandwidth,
equipment, and co-location facilities to maintain a robust solution, P2P
can offer a similar level of robustness by spreading network and
resource demands across the P2P network.
Unfortunately, P2P suffers from some disadvantages
due to the redundant nature of a P2P network’s structure. The
distributed form of communications channels in P2P networks results
in service requests that are nondeterministic in nature. For example,
clients requesting the exact same resource from the P2P network
might
connect
to
entirely
different
machines
via
different
communication routes, with different results. Requests sent via a P2P
network might not result in an immediate response and, in some
cases, might not result in any response. Resources on a P2P network
can disappear at times as the clients that host those resources
disconnect from the network; this is different from the services
provided by the traditional Internet, which have most resources
continuously available. P2P overcomes this disadvantage by providing
redundant access to a resource.
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8. Existing System
In the client/server architecture, clients request services and
servers provide those services. Clients connect to a server using a
specific communications protocol, such as the File Transfer Protocol
(FTP), to obtain access to a specific resource. Most of the processing
involved in delivering a service usually occurs on the server, leaving
the client relatively unburdened.
The client in the client/server
architecture acts in a passive role, capable of demanding services from
servers but incapable of providing services to other clients. This model
of service delivery was developed at a time when most machines on
the Internet had a resolvable static IP address, meaning that all
machines on the Internet could find each other easily using a simple
name.
Limitations of the current system
The disadvantage of using client-server architecture is that
as the number of clients increases, the load and bandwidth demands
on the server also increase, eventually preventing the server from
handling additional clients.
Objective
The main objective of this project is to send instant messages
within a peer group in a decentralized network using JXTA technology.
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9. Proposed System
The existing system operated on a client/server
mechanism
in
which
a
centralized
server
is
required.
While
communicating between the peer members in the JXTA network i.e.,
the proposed system, a peer name has to be given by the user in the
configurator window. The user is identified in the network using the
peer id. The peer member can secure his identification using the
password. The user should have an idea regarding the identification of
another person. Thorough knowledge of
identifying the members,
adding the peers in the network, deleting the members from the
network are required.
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10. Hardware & Software Requirements
•
Pentium IV Processor – 2 GHZ
•
NIC – 32 Bit Ethernet Card
•
40 GB HDD
•
256 MB DDR RAM
•
Mobile Phone
•
JXTA Proxy Server
•
J2SDK 1.4.2_06
•
J2ME WTK 2.0
•
Windows 2000 Server
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11. The project Peer-to-Peer Messaging is divided into three major
modules:
•
Element
•
Message
•
Peer Network
ELEMENT MODULE
The Element represents a single element of the JXME
message. The JXME implementation uses the Element to author JXME
messages. A pure P2P system does not require the existence of any
centralized servers or resources to operate. Therefore, a P2P system
must not rely on any centrally administered naming or addressing
system.
The first module of the project deals with entering the
member into the JXTA network and to enable them to chat with other
members of the group. Batch file called myjxta will be run first. In the
advanced settings tab, TCP option has to be enabled. Incoming and
outgoing connections has to be enabled. Port number of the system
has to be provided in the http settings. The peer who wants to become
the member of the JXTA group will enter with the peer name. Only
authenticated users can enter the network as password is required. In
the relay host, proxy id should be given for communicating with the
other peer. When all the settings are completed, the peer member has
entered the network and is ready to communicate with all members in
the NetPeerGroup.
MESSAGE MODULE
The message module is designed for the peer members to
communicate with each other in the network. JXME does not define
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12. any special request message that explicitly asks the relay to send one
or more response messages it has for the JXME client. The JXME client
continues to send requests (for example, a peer group join request, a
pipe creation request, or a search query) or other outbound messages
to the relay. The relay avails these requests as opportunities to send
any incoming message to the JXME client in response to a request. The
JXME client uses the request Id element in the response message to
find out which request this response corresponds to.
JXTA peers use pipes to send messages to one another. Pipes
are an asynchronous and unidirectional message transfer mechanism
used for service communication. Pipes are indiscriminate; they support
the transfer of any object, including binary code, data strings, and
Java technology-based objects. The pipe endpoints are referred to as
the input pipe (the receiving end) and the output pipe (the sending
end). Pipe endpoints are dynamically bound to peer endpoints at
runtime.
Peer
endpoints
correspond
to
available
peer
network
interfaces (e.g., a TCP port and associated IP address) that can be
used to send and receive message. JXTA pipes can
have endpoints that are connected to different peers at different times,
or may not be connected at all.
PEER NETWORK MODULE
The Peer Network contains the methods to allow the JXME
communication
with
the
relay.
The
Peer
Network
is
like
a
communication module that internally uses different Message and
Element objects and handles all communication with the relay. Peer
Network has methods to perform the various tasks between the relay
and the mobile client. The Peer Network manages all the messages
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13. and maintains the support tasks, maintaining the identity of various
messages exchanged between the relay and the client.
The third module deals with the implementation of communication
between JXTA peers in the midlet. Proxy id should be given and the
peer enters the group with a peer name. There are various options like
sending the message, reply, connect to the relay, Buddy list,
configuration
and
default
settings.
Using
the
various
options,
messages can be sent, reply can be sent to the received message and
connection can be established with the relay. Using the buddy list
menu, members can chat, new members can be added to the group
and the members can also leave the group.
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