Officials at EarthLink’s R&D
facility have quietly released a proof-of-concept file-sharing
application based on the Session Initiated Protocol
SIPshare,
written by EarthLink R&D staff and released to the open source
community on its R&D discussion
forum late Wednesday, demonstrates the viability of SIP as a
protocol over which peer-to-peer (P2P) applications may be implemented
beyond voice and video cases.
SIP is an IETF
initiating an interactive user session that involves multimedia elements,
such as video, voice, chat and gaming. It is mostly used to power Voice over IP
implementations can be extended to P2P applications for enterprise use.
The R&D unit said SIPshare includes features for
peer discovery, content search, file transfer and downloading using SIP
messaging.
For example, content searches are passed from one peer to all other
known peers, which allows content to be located on a host that the original
requesting peer is not aware of. Once the content is
located, it uses the SIP Invite feature to request the content from the
known host.
Another feature, the distributed content search tool,
lets users share documents, photos and other files via SIP and a
UDP-based file transfer protocol. The UDP
a direct way to send and receive broadcast messages over an IP network.
According to Mark Petrovic, EarthLink vice president of R&D, the ISP
wrote it to convince themselves and others that modern P2P applications
can be written on top of SIP. In his note, Petrovic made it clear the SIPshare application was
“alpha code at best” and warned that it should not be used for mission-critical applications.
“Feel free to extend it, modify it,” he said. “But we do
not advise using it for anything that matters.”
EarthLink said a
belief that “an open Internet is a good Internet,” motivated the release of the P2P prototype.
“An open Internet means users have full end-to-end connectivity to
say to each other whatever it is they say, be that voice, video, or
other data exchanges, without the help of mediating servers in the
middle whenever possible,” the company said. “We believe that if peer-to-peer flourishes,
the Internet flourishes. SIPshare helps spread the word that SIP is
[much more] than a powerful voice over IP enabler.”
This is not the first time that SIP has been associated with the
peer-to-peer concept. A P2P infrastructure is being used to handle
IP-based phone calls on Skype,
which is a Net phone service launched by the founders of Kazaa.
However, EarthLink’s researchers believe SIPshare differs
from Skype because it uses standards-based protocols to
handle content sharing.
“The emerging ubiquity of SIP as a general session-initiation enabler
provides a rare opportunity to offer users all manner of P2P
applications over a common protocol, instead of inventing a new protocol
for each new P2P application that comes along,” the ISP argued.
“EarthLink wants to point the way and aid the cause of these new
applications by demonstrating in open source working code that SIP can
host powerful applications beyond those that immediately come to mind,
that is, voice and video,” the company added.
It is written for Java 2 Standard Edition (J2SE) and
runs on any platform for which a J2SE virtual machine is available,
including Windows, Linux, Mac OS X and Solaris.
The company said SIPshare is not a supported EarthLink
product.
