TANGO Interactive is started by clicking a link. What happens then? The browser goes to the Tango Interactive Application Server and downloads the Session Manager (SM). Technically, SM is a Java applet. TANGO Interactive SM knows how to talk to the plugin and make it do various things. TI Application Server is an HTTP server that hosts SM code and all auxiliary files, as well as a suite of TI application modules. Applications hosted on an Application Server are downloaded at run time, in contrast to local applications described in the TI Client section.
An important fact to understand is that the SMs of different users can get downloaded from different TI Application Servers. Actually, the SMs don't even have to be the same. This allows us to build interesting system topologies. More importantly, it means that you can obtain a distribution of the SM and application modules software and install it on your own HTTP server. By doing so, you become an ASP for yourself and perhaps for a selected group of users. Such configurations are usually dictated by the geographical conditions and network performance requirements. Another advantage of having your own TI Application Server is that you can set it up and configure according to your own business rules.
After the SM is up and running, you can start TANGO Interactive application modules. As mentioned above, the application modules are either local (in which case they are started from the pre-installed executables) or remote, in which case they are downloaded from a TI Application server. The location of the application code is defined in the SM configuration files. The application modules can be downloaded from arbitrary TI Application Servers: one SM can provide a GUI to a collection of application modules, each coming from a different location. This feature of the system is used to build scalable distributed collaborative computing infrastructure, with multiple TI Application Servers providing load-balancing capability, and with various ASPs contributing different functionality to the overall system.
While this description may seem complicated, in reality the system architecture of TANGO Interactive is an almost obvious outgrowth of the basic Web client-server technology. The idea of application service providers, or ASPs, is a hot business topic now, but technically it is a direct consequence of technologies such as Java, ActiveX, and Web page scripting. TANGO Interactive consequently makes use of all technical features offered by the Web infrastructure. The resulting system is a extremely flexible, powerful, and highly usable framework for collaborative computing. |