Gary Ogasawara
VP Engineering
Gemini Mobile Technologies, Inc.
www.geminimobile.com
 

Position Paper: 
Gemini's eXplo application is a mobile 3-D social community platform that
includes both server and client code.  Functions available are avatar
navigation in a 3D cell-based world, search/matching, instant messaging,
store-and-forward messaging, and integration with third-party content and
applications.  This application is deployed by Softbank Mobile in Japan as
S!TOWN and has over 150,000 registered users.

The over-the-air control and data exchanged in the application is fairly
large, for example, 2 MB for the world map.  In addition, frequent updates
are necessary over persistent connections to update instant messages and
presence and position data of other avatars.   

For user profile and data manipulation, eXplo uses HTTP using XCAP protocol
for PUT/GET/DELETE of data objects in the data.  The HTTP body data is
encoded as XER (XML Encoding Rules) or BER (Basic Encoding Rules).  

For the persistent TCP connections, a form of the Session Initiation
Protocol (SIP) is used.  HTTP is still the "bearer" protocol and SIP is
carried inside the HTTP requests and responses.  These persistent
connections are used for the instant messaging, presence, and map updating
between multiple avatars.

Network bandwidth and connectivity limits negatively impact the richness of
the applications that can be deployed with eXplo.  We are actively seeking a
way to reduce the amount of data transmitted between client and server.
Though we have not implemented Ajax in any way yet, we see it as part of a
potential solution.  (By end-September, we probably will have done some
prototyping with Ajax.)