[p2p-hackers] Project Announcement: P2P Sockets

[Brad Neuberg]

Hi everyone.  I just posted the web site, source code,
and two tutorials for the Peer-to-Peer Sockets Project
at http://p2psockets.jxta.org.  The source code
represents a
working, 1.0 beta 1 release, with several pieces of
software, such as Jetty and XML-RPC Client and Server
libraries, already ported onto this new API.  I have
spent the last month and a half working full time on
this.  Here are some more details on the project:

------------------------

Are you interested in:

    * returning the end-to-end principle to the
Internet?
    * an alternative peer-to-peer domain name system
that bypasses ICANN and Verisign, is completely
decentralized, and responds to updates much quicker
than standard DNS?
    * an Internet where everyone can create and
consume network services, even if they have a dynamic
IP address or no IP address, are behind a Network
Address Translation (NAT) device, or blocked by an
ISP's firewall?
    * a web where every peer can automatically start a
web server, host an XML-RPC service, and more and
quickly make these available to other peers?
    * easily adding peer-to-peer functionality to your
Java socket and server socket applications?
    * having your servlets and Java Server Pages work
on a peer-to-peer network for increased reliability,
easier maintenence, and exciting new end-user
functionality?
    * playing with a cool technology?

If you answered yes to any of the above, then welcome
to the Peer-to-Peer Sockets project! The Peer-to-Peer
Sockets Project reimplements Java's standard Socket,
ServerSocket, and InetAddress classes to work on a
peer-to-peer network rather than on the standard
TCP/IP network. "Aren't standard TCP/IP sockets and
server sockets already peer-to-peer?" some might ask.
Standard TCP/IP sockets and server sockets are
theoretically peer-to-peer but in practice are not due
to firewalls, Network Address Translation (NAT)
devices, and political and technical issues with the
Domain Name System (DNS).

The P2P Sockets project deals with these issues by
re-implementing the standard java.net classes on top
of the Jxta peer-to-peer network. Jxta is an
open-source project that creates a peer-to-peer
overlay network that sits on top of TCP/IP. Ever peer
on the network is given an IP-address like number,
even if they are behind a firewall or don't have a
stable IP address. Super-peers on the Jxta network run
application-level routers which store special
information such as how to reach peers, how to join
sub-groups of peers, and what content peers are making
available. Jxta application-level relays can proxy
requests between peers that would not normally be able
to communicate due to firewalls or NAT devices. Peers
organize themselves into Peer Groups, which scope all
search requests and act as natural security
containers. Any peer can publish and create a peer
group in a decentralized way, and other peers can
search for and discover these peer groups using other
super-peers. Peers communicate using Pipes, which are
very similar to Unix pipes. Pipes abstract the exact
way in which two peers communicate, allowing peers to
communicate using other peers as intermediaries if
they normally would not be able to communicate due to
network partitioning.

Jxta is an extremely powerful framework. However, it
is not an easy framework to learn, and porting
existing software to work on Jxta is not for the
faint-of-heart. P2P Sockets effectively hides Jxta by
creating a thin illusion that the peer-to-peer network
is actually a standard TCP/IP network. If a peer
wishes to become a server they simply create a P2P
server socket with the domain name they want and the
port other peers should use to contact them. P2P
clients open socket connections to hosts that are
running services on given ports. Hosts can be resolved
either by domain name, such as "www.nike.laborpolicy",
or by IP address, such as "44.22.33.22". Behind the
scenes these resolve to JXTA primitives rather than
being resolved through DNS or TCP/IP. For example, the
host name "www.nike.laborpolicy" is actually the NAME
field of a Jxta Peer Group Advertisement. P2P sockets
and server sockets work exactly the same as normal
TCP/IP sockets and server sockets.

The benefits of taking this approach are many-fold.
First, programmers can easily leverage their knowledge
of standard TCP/IP sockets and server sockets to work
on the Jxta peer-to-peer network without having to
learn about Jxta. Second, all of the P2P Sockets code
subclasses standard java.net objects, such as
java.net.Socket, so existing network applications can
quickly be ported to work on a peer-to-peer network.
The P2P Sockets project already includes a large
amount of software ported to use the peer-to-peer
network, including a web server (Jetty) that can
receive requests and serve content over the
peer-to-peer network; a servlet and JSP engine (Jetty
and Jasper) that allows existing servlets and JSPs to
serve P2P clients; an XML-RPC client and server
(Apache XML-RPC) for accessing and exposing P2P
XML-RPC endpoints; an HTTP/1.1 client (Apache Commons
HTTP-Client) that can access P2P web servers; a
gateway (Smart Cache) to make it possible for existing
browsers to access P2P web sites; and a WikiWiki
(JSPWiki) that can be used to host WikiWikis on your
local machine that other peers can access and edit
through the P2P network. Even better, all of this
software works and looks exactly as it did before
being ported. The P2P Sockets abstraction is so strong
that porting each of these pieces of software took as
little as 30 minutes to several hours. Everything
included in the P2P sockets project is open-source,
mostly under BSD-type licenses, and cross-platform due
to being written in Java.

Because P2P Sockets are based on Jxta, they can easily
do things that ordinary server sockets and sockets
can't handle. First, creating server sockets that can
fail-over and scale is easy with P2P Sockets. Many
different peers can start server sockets for the same
host name and port, such as "www.nike.laborpolicy" on
port 80. When a client opens a P2P socket to
"www.nike.laborpolicy" on port 80, they will randomly
connect to one of the machines that is hosting this
port. All of these server peers might be hosting the
same web site, for example, making it very easy to
partition client requests across different server
peers or to recover from losing one server peer. This
is analagous to DNS round-robining, where one host
name will resolve to many different IP addresses to
help with load-balancing. Second, since P2P Sockets
don't use the DNS system, host names can be whatever
you wish them to. You can create your own fanciful
endings, such as "www.boobah.cat" or
"www.cynthia.goddess", or application-specific host
names, such as "Brad GNUberg" or "Fidget666" for an
instant messaging system. Third, the service ports for
a given host name can be distributed across many
different peers around the world. For example, imagine
that you have a virtual host for
"www.nike.laborpolicy". One peer could be hosting port
80, to serve web pages; another could be hosting port
2000, for instant messaging, and a final peer could be
hosting port 3000 for peers to subscribe to real-time
RSS updates. Hosts now become decentralized coalitions
of peers working together to serve requests.

Two tutorials are available:

    * Introduction to Peer-to-Peer Sockets -
http://www.codinginparadise.org/p2psockets/1.html
    * How to Create Peer-to-Peer Web Servers,
Servlets, JSPs, and XML-RPC Clients and Servers -
http://www.codinginparadise.org/p2psockets/2.html

Download P2PSockets-1.0-beta1.zip, (released 9-5-2003)
which contains the core package and extensions both
compiled and in source form, at
http://www.codinginparadise.org/p2psockets/P2PSockets-1.0-beta1.zip

Thanks,
  Brad GNUberg
  bkn3 at columbia.edu
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Here is a web page listing P2P Conferences:
http://www.neurogrid.net/twiki/bin/view/Main/PeerToPeerConferences

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